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WRNYSTATION Edited by HUGO GERNSBACK TELEVISION NUMBER HOW TO BUILD YOUR OWN TELEVISION RECEIVER SEE PAGE 422
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www.americanradiohistory.com Power Supply Transformers These transformers supply full wave rectifiers using two UX -281 tubes, for power amplifiers using either 210 or 250 types power ampli- fying tubes as follows: T -2098 for two 210 power tubes, $20.00; T -2900 for single 250 power tube, $20.00; T -2950 for two 250 tubes, $29.50.
Double Choke Units =0) Consist of two 30 henry chokes in one case. T -2099 for use with power sup- ply transformer T -2098, $14; T-3099 for use with transformer T -2900, $16; T -3100 for use with transformer 3 ö s °N T-2950, $18. TIIORIDA Power Compacts A very efficient and compact form of AUDIO TRANSFORMER power supply unit. Power transform- er and filter chokes all in one case. Type R -171 for Raytheon rectifier and UPREME in musical performance, the 171 type power tube, $15.00; Type new Thordarson R -300 Audio R -210 for UX -281 rectifier and 210 Trans- power tube, $20.00; Type R -280 for former brings a greater realism to radio UX -280 rectifier and 171 power tube, reproduction. Introducing a new core mate- $17.00. rial, "DX- Metal" .(a product of the Thordar- Speaker Coupling Trans- son Laboratory), the amplification range has formers been extended still further into lower reg- A complete line of transformers to at the couple either single or push -pull 171, ister, so that even the deepest tones now may 210 or 250 power tubes into either \_` high impedance or dynamic speakers. I1IÍiö.' -, be reproduced with amazing fidelity. _._ Prices from $6.00 to $12.00. The amplification curve of this transformer Screen Grid Audio Coupler is practically a straight line from 30 cycles to The Thordarson Z- Coupler T -2909 is 8,000 cycles. A high frequency cut -off is pro- a special impedance unit designed to vided at 8,000 cycles to confine the amplifica- couple a screen grid tube in the audio amplifier into a power tube. Produces tion to useful frequencies only, and to elimi- excellent base note reproduction and nate undesirable scratch that may reach the amplification vastly in excess of ordi- audio transformer. nary systems. Price, $12.00. r When you hear the R -300 you will appre- THORDARSON ELECTRIC MFG. CO. ciate the popularity of Thordarson trans- 500 W. Huron St., Chicago, Ill. 3583.1. formers among the leading receiving set man- Gentlemen: Please send me your constructional ufacturers. The R -300 retails for $8.00. booklets on your power amplifiers. I am especially interested in amplifiers using tubes. THORDARSON ELECTRIC MANUFACTURING CO Name Transformer Specialists Since 1895 WORLDS OLDEST AND LARGEST EXCLUSIVE TRANSFORMER MAKERS Street and No `7furon and Kingsburo Streets Chicago.1ll.11SA. - Town
www.americanradiohistory.com Radio News for November, 1928 -s01
EARNED $500 SPARE TIME WITH RADIO
Coplay, Pa., June 4 -(RA)- During the few months that Frank J. Deutsch has been a member of the Radio Association of America, he has made over $500 out of Radio in his spare time. "Four super -heterodyne sets of my own construction brought me a profit of $60.00 each, and the other profit was from sales E\CII of these plans, developed by tic lladio Association of America, is a big stoney -maker. of supplies purchased through the Whole- Set owners everywhere want to get rid of static, to sale Department. of the Association," he have their sets operate from the electric light socket, said. "The Association certainly has a the tone improved, and the volume increased, and great transformed into single-dial controls. Phonograph plan for ambitious men." owners want their machines electrified and radiofied. In a neighboring state, Werner Eichler, If you learn to render these services, you can easily Rochester, N. Y., another member of the make $3.00 an hour for your spare time, to say nothing Association, has been making $50 a week of the money you can make installing, servicing, repairing, sets, selling during his spare time. and building radio and supplies. They are only two of the hundreds of Over $600,000,000 is being spent yearly for sets, Radio Association members who are making supplies, service. You can get your share of this business fit money Radio in spare time. and, at the same time, yourself for the out of their big -pay opportunities in Radio by joining the Association. BECOMES RADIO ENGINEER IN Join the ONE YEAR Radio Association Toronto, Canada, May 20 -(RA) -One of the newly admitted associate members of America of the Institute of Radio Engineers is A membership in the Association offers you the (laude DeGrave, a member of the engi- easiest way into Radio. It will enable you to earn f33.00 an hour upwards in your spare time neering staff of the DeForest Company of -train you to install, repair, and build all kinds of sets - t his city. "I knew nothing about Radio start you in business without capital or finance an and started from the ground up," Mr. invention -train you for the $3,000 to $10.000 big - DeGrave stated, "when I enrolled a year pay radio positions -help secure a better position at A membership need coat ago in Association. bigger pay for you. not iion the Radio Its easy a cent! lessons and superb training made it possible for me to become a Radio Expert in less 'l'he Association will give you a comprehensive, practical, and theoretical training and the benefit than a year's time. My income is now of our Employment Service. You earn while you about ;225'¿ more than at the time I joined learn. Our cooperative plan will make it possible for the Association." you to establish a radio store. You have the privilege The Institute of Radio Engineers is a very of buying radio supplies at wholesale from the very exclusive organization, and its membership first. requirements are very rigid, so that Mr. DeGrave has reason to be proud of his ACT NOW -If you wish election. No -Cost Membership Plan To it limited number of ambitious men, we will give Clerk Doubles Income In Special Memberships that may not -need not -cost Six Through you a cent. To secure one, write today. We will Months Radio MODERNIZE OLD SETS send von details and also our book, "Your Opportunity Chicago, Ill., May 9-Even though his WITH ONE DIAL CONTPAL in the Radio Industry." It will open your eyes to the money-making possibilities of Radio. membership in the Radio Association has resulted in W. E. Thon securing the manager- ship of a Radio Department in a large COUPON Chicago store, his ambition was not satisfied. RADIO ASSOCIATION OF .AMERICA Six months later, he started his own store. Dept. RN -11, 4513 Ravenswood Ave., "The Radio Association has an excellent Chicago, Ill. plan for the man who wants to get out of Gentlemen: Please send nie by return mail full details of your the rut and succeed," says this man who Special Membership Plan. and also ev,py of your quickly rose from clerkdom to the pro- look, "Your Opportunity in the Radio Industry:' prietorship of a profitable radio store. "I Name attribute my success entirely to the Radio Association of America. Six months after Address I had enrolled, I had doubled my income City State through its help." Please say you saw it in RADIO NEINS www.americanradiohistory.com 402 Radio News for November, 1928
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NOVEMBER, 1928 Number 5
HUGO GERNSBACK, Editor -in-Chief ROBERT HERTZBERG, M:.naging Editor C. P. MASON, Associate Editor BERYL B. BRYANT, Laboratory Director C. WALTER PALMER, Director Information Service
Contents of This Issue Future Progress in Television ta "Rays of Justice" By C. Sterling Gleason 432 By Hugo Gernsback 411 What's New in Radio 434 Successful Television Programs Broadcast Putting the Aerial in Shape for Winter by RADIO NEWS Station WRNY By L. B. ltuuuins 437 By Robert Hertzberg 412 Electrodynamic Speakers Become Popular "Radio Movies" from KDKA 41G By Fred H. Canfield 438 How "Stereoscopic" Television is Shown The Radio Beginner -Sonie Facts About By R. F. Tiltman 418 Transformers By C. Walter Palmer 442 Broadcastatics 445 Televentures, Telewitticisms and the Televoca hula ry 419 How to Construct the "Pre- Selector" By S. Gordon Taylor 446 The Jenkins "Radio- Movie" Reception Methods 420 Magneto -Striction By M. J. Cuttler 450 Amplifier Successful DX Work Marks "Radio - Ways of Sensitizing the R.F. with Stability 453 Movie" Transmissions 421 Radio Wrinkles 45.4 Synchronized Broadcast Joins Images and Music 426 On the Short Waves 456 The Neon Tuhe - Television's "Loud The Radio Constructor's Own Pages 458 Speaker" By D. E. Replogle 427 RADIO NEWS Laboratories 460 How to Adjust the Television Receiver I Want to Know By C. W. Palmer 462 428 for Operation Radiotics 470 Television Teems with Trials for Telex - Force 472 perimenters 429 Radio as an Advertising
List of Broadcast Station Calls 430 zia Radio "Bugs" 474
RADIO NEWS 1s published on the 10th of each preceding month. There are 12 obtained from the publishers. Copyrighted in Germany. Reproduction of articles numbers per year. Subscription price is 22.50 a year in U. S. and possessions. in Germany is reserved for Radio. Berlin 42. Canada and foreign countries, $3.00 per year. U. S. Coin as well as U. S. Stamps RADIO NEWS is for sale at all newsstands in the United States and Canada, accepted (no foreign coins or stamps). Single copies, 25 cents each. Checks and and at Brentanó s, Ave. de L'Opera, Paris, France. European agents: S. J. Wise money orders should be drawn to order of E_XPERDIENTER PUBLISHING Et Cie, 40 Place Verte, Antwerp, Belgium. CO., INC. HOW TO SUBSCRIBE FOR RADIO NEWS. Send your name, address and re- All communications and contributions to this journal should be addressed to mittance to Experimenter Publishing Co., 230 Fifth Ave.. New York. Mention the Editor. RADIO NEWS, 230 Fifth Ave., New York, N. T. Unaccepted contribu- name of the magazine you are ordering. We also publish SCIENCE AND INVEN- tions cannot be returned unless full postage has been included. All accepted con- TION, RADIO LISTENERS' GUIDE and AMAZING STORIES. Write clearly. tributions are paid for on publication. A special rate Is paid for novel experi- RATES AND TERMS. The subscription rate for RADIO NEWS is 22.50 per ments; good photographs accompanying them are highly desirable. Publishers are year. (12 numbers). When remitting do so by check. money order, or registered not responsible for loss of manuscripts, although every precaution is taken with letter if rash is enclosed. Avoid sending cash through the mall if possible. Sub- such manuscripts. upon receipt thereof. scriptions for less than one year are nut accepted. Subscription may be made in RADIO NEWS. Monthly. Entered as second -class matter, July 12, 1924, at the combination with SCIENCE 8- IilT'ENTION, RADIO LISTENERS' GUIDE. Post Omre at New York, N. Y., under the Act of March 3. 1879. Additional entry and AMAZING STORIES. at Dunellen. N. J. and San Francisco, Calif. Tille registered U. S. Patent Office, POSTAGE. We prepay postage in all parts of the United States, Mexico and Copyright, 1928. by The Experimenter Publishing Co.. Inc., 230 Fifth Ave., island possessions. For foreign or Canadian subscriptions we require 50 cents in addition to the subscription price for additional postage charge. Translatedreproduced 1i the United States without gntnggiving full credit to the publication. CHANGE OF ADDRESS. Notify us as far in advance as possible. It requires Translation into foreign languages must not be merle unless permission is several weeks to make an address change on our records. Always write clearly. The contents of RADIO NEWS are indexed in the Industrial Arta Index, coptes of which can be found in every library.
Published by Experimenter Publishing Company, Inc. H. GERNSBACK, President S. GERNSBACK, Vice -President and Treasurer ALFRED A. COHEN, Secretary Member: Audit Bureau of Circulations Radio Magazine Publishers Association Advertising Representatives: RHODES & LEISENRING New York Offices: 624 Graybar Building Chicago Offices: 307 North Michigan Ave. Editorial and General Offices 230 Fifth Avenue, New York City
www.americanradiohistory.com Radie News for November, 1928 403
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The PACKARD Engineers have invented this most unusual, powerful SUPER - Eight Tube Radio. Astonishing volume and tone quali- ty. Remarkable selectivity and long -distance recep- tion. Leading radio engineers unanimously agree that there is no better radio made - regardless of price. Let us prove this by shipping a set to your home on 30 days' trial. Examine the set from A to Z. Let the most WORLD'S GREATEST RADIO exacting critics pass on its merits. And if, after the 30 Genuine Walnut Console Cabinet day trial period, you are convinced that the Packard Eight -tube Electric is fully the equal of any console Eight powerful A. C. tubes and one genuine full - radio set selling up to $2S0 -then, and only then, need wave rectifying tube -nine tubes in all. Supreme you decide it $99 quality throughout. Simple to operate. Connect the to keep at our factory price of only plug to electric socket and turn switch. Only one -otherwise, return it. dial to tune. One hundred per cent electric. Hand- This marvelous set combines new some walnut cabinet -two -tone genuine DUCO fin- every scientific de- Marvel- velopment in receiving sets beauty, refine- ish. Metal trimming finished in old gold. -possessing ous built -in, powerful speaker. Size of cabinet is 54 ment, durability. Gets everything on the air from coast inches high, 27 inches wide. to coast -from Mexico into Canada, loudly, clearly, and distinctly. Only one dial to tune in all stations. You Save the Jobbers', Dealers' and Salesmen's Profits The PACKARD Radio is shipped direct from our factory. All the in- between profits are deducted from the price of the set and instead of paying $250 you pay only $99. Quantity Packard Radios are also production, economy in selling, and only a small profit made for BATTERY OPERATION for the manufacturer makes this astounding offer possible.. PRICED AS LOW AS $53 MAIL COUPON NOW FOR P 30 days' free Packard Radio Company trial offer Nr 2323 Milwaukee Ave., Dept. 321, Chicago, Ill. Don't miss this opportunity. Mail coupon at once for complete inform- I am interested in Packard Radios and your S5,000.00 ation about the PACKARD A. C.- 8 TUBE ELECTRIC RADIO and Bonded 30 days' free trial offer and guarantee. Send our liberal 30 days' free trial offer. No obligation on your part. Our full details. $5,000.00 cash bond backs up our guarantee. Name PACKARD RADIO CO. Address-.. 2323 Milwaukee Ave. Dept. 321 Chicago, Ill. City State
c a p v oLt saw it in RADIO NEWS www.americanradiohistory.com 40 -i Radio News for November, 1928
INDEX TO ADVERTISERS
Page Page Page A N Pathfinder 483 .1cro Products, Inc 480 Fanspeaker Radio Co 482 Per -Con Mfg. Co 491 Aerovox Wireless Corp 482 Flechtheini & Co., Inc., A. M 485 Potter Mfg. Co 490 Allied Radio Corp. Freshman Co., Inc., Chas 483 Press Guild, Inc 499 482- 489 -490 -492- 503 -507 -509 -510 -512 G R Aluminum Company of America 467 General Radio Co 508 Radiali Co. 503 American Radio & Mere. Co 496 Gernsback, S. 502 Radio Association of America 401 American Sales Co 497 Gray & Danielson Mfg. Co 486 Radio Doctórs, Inc 487 American Transformer Co 482 Gustin- Bacon Mfg. Co 508 Radio Equipment Co 503 Arcturus Radio Co 506 H Radió Institute of America 499 B Hammarhmd Mfg. Co 487 Radio Producer Co 490 Barawik Co., The Hanimarlund- Roberts, Inc. 408 Radio Specialty Co 471 476 -480- 483- 485 -486 -491 -492- 495 -496- Hotel Lafayette 501 Raytheon Mfg. Co 472 498 -501- 503 -505 -506-507 -509 -510 Hotel McAlpin 490 Belden Mfg. Co 501 S Benjamin Electric Mfg. Co 505 I Scott Transformer Co Inside Back Cover Browning -Drake Corp. 496 Illinois Transformer Co 503 See Jay Battery Co 483 Independent Electric Works 480 Setbuilders Supply Co 407 -480 C J Shanklin Mfg. Co 482 Radio Co 507 Carter Silver JIarshall, Inc. _ J -M -P Mfg. Co 505 406 CeCo Mfg. Co 474 Smith, B. Hawley 507 Radio Labs 494 K Central Southern Toy Co 496 Chemical Inst. of N. Y., Inc 473 Maras Electric Co. 489- 493 -507-509 T Chicago Radio Apparatus Co 50.5 Knapp Electric Co 481 'l'arbell System, Inc 498 Chicago Stock Gear Works 495 L Teleplex Co. 509 Clark & Tilson, Inc 495 Lacault, Inc., R. E 479 Televocal Corp. 509 Consrad Co., Inc., The 494498 Lacey and Lacey 507 Thodarson Elec. Mfg. Co. Consumers Radio Co. 503 Leutz, Inc., C. R 410 Inside Front Cover Coyne Electrical School 506 Lynch, Inc., Arthur H 501 Townsend Labs. 489 Craftsman Radio Products 476 Mc Transformer Corp. of America 486 Cunningham, Inc., E. T 466 McSweeney Electrical Schools 595 '' yrman Elec. Corp 511
D M U
31assachusetts _ Daven Radio Corp 491 -498 Radio & 'l'el. School 483 Underground Aerial Systems 469 1)eForest Radio Co., The 506 Metro Electric Co 465 V Deutschmann Co., Tobe 476 Midwest Radio Corp. Back Cover Van Ashe Radio Co 4811 Diamond Radio Co 507 N W Directory Section of Radio News 477 National Co Inc 491 Walker Co., The Geo. W 468 ])resner Radio Mfg. Corp 494 National Electrical School 486 Webster Co., The 509 Dubilier Condenser Corp 470 National Radio Institute 405 -475 Western Radio Mfg. Co 497 New England Mills 494 E Co Wirt Co. 49.2 Norden- Hauck, Inc. 483-495 Electrad, Inc. 485 -493 X Electric Specialty Co 497 O Mfg. X -L Radio Labs. I!lectro- Chemical Company of America 486 Oak Park Co 494 506 Elkon, Inc. 409 P Y
Excello Products Corp 505 Packard Radio Co 403 Yaxley Mfg. Co 503 .Please .car von saw it in RADIO NEWS www.americanradiohistory.com 405 Radio News for November, 1928 FflEE . Mnr.e's the dopeXouve been1ookini for HOW TO GET INTO THE RADIO BllSINESS.
4
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With them 3 ou can build 100 different circuits -learn the "how" and "why" of practically every type of Radio set made. This kind of training fits you to HaveTrained .tep into the good jobs -sends you out an experienced Radio expert. When O you complete, my Employment Department will help you get a real big Radio Hundreds of job like Graduate Edward Stanko, now Chief Operator of Station WGR, or Frank M. Jones, 922 Guadalupe St., San Angelo. Tex., builder and operator Men Home of Station KGFI and Manager of the best equipped Radio shop in the at or help start a Radio business of your own like Richard Southwest, you S500 a month for Big' Radio Smith, Butler, 1419 No. 17th St., Phila., Pa., who made around President.dent. compared with a small salaried, no future job as motorman when he enrolled. National Radio Jobs. Institute, My Radio Training is the Famous "Course That Dept. 335, Pays for Itself MyBookProves Washington, D. C. from the time enroll. Dear Mr. Smith: Spare time earnings are easy in Radio almost you I Can loo the Without obligating me W. Page, 1807 21st Ave. S., Nashville, Tenn., made 5935 in his spare G. Sandusky. O.. In any way, send me your time while taking this course. Al. Johnson, 1409 Shelby St.. Same for big FREE BOOR, 'Rieh $1,000 in four months, and he didn't know the difference between a condenser Rewards In Radio," and all and a transformer when he enrolled. I'll give you a legal contract, backed by Information about your pi aetlml N. R. I., pioneer and largest home- study Radio school in the world, to You. home-sus :3. Radio ('. arse. your money if you are not satisfied, upon completing, refund every penny of offers with the lesson., and instructions received. Find out what Radio Name Age you -get the facts. Mail coupon- RlCH'l' NOW. Address ACT NOWA000UPON BRINGS MY Town State
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www.americanradiohistory.com 406 Radio News for November, 1928
Down to "BRASS TACKS ON AUDIOS (whether it hurls or not)
"Silver- Marshall unconditionally guarantees the new S -M Clough system audio transformers to give greater amplification, finer tone, and less distortion than any standard transformers marketed by any other Amer- ican manufacturer."
CONTRAST this straight- from -the -shoulder guarantee with the advertising phrases used by other manufacturers-not one dares offer the guarantee that S -M has given for two consecutive years -ever since the were produced. first 220 transformers Not all radio fans have been able to attend the public comparative tests that S -M engineers have been making at the R. M. A. trade show in cities. These and the larger Eastern are the very surest proof that the new transformers are far superior to any and all other types. If you find it hard to believe that any transformers so far can be ahead of the audio equipment which you have been using, we can only say o you: "Buy a 225 and a 226, 255 or a and a 256; hook them up properly and test - them. Then, if you're not satisfied that they are better heard, than anything you've ever return them to the factory for full credit." The fan unwilling to accept such an offer- content with transformers now far outclassed not and progressive -is the open-minded type to whom S -M appeals, and who will find in the new S -M transformers a quality of reproduction beyond his fondest expectations. Research engineers- eminent designers-men who know, not guess -all acknowl- edge the supremacy of S -M audio transformers. This is a strong statement to make, but we back it up with a guarantee such as no other manufacturer has offered on audio transformer equipment. S -M Clough System audios are, in absolute fact, two years ahead -as truly as were the S -M 220's when, two years ago, they intro- duced the high frequency cutoff only recently adopted Remember by other manufacturers. this when selecting audio amplifying equipment -remember that S -M is the only manufacturer that has ever dared to make or encourage public com- parative tests in comparison amplifiers open and accessible to minute, detailed examination by all listeners -and remember the above -quoted positive guarantee!
If you don't wish to build, yet want your radio to be custom made, with all the ad vantages that this implies, S M will gladly refer your inquiry to an Authorized IN the chart at the right, E Silier-Marshall Service Station near you.' is the two -stage curve for on the other hand, you build sets pro- fessionally, and are interested in learning the large-size transformers whether there are valuable Service Station (S-M 225, Ist stage; and 226, franchises yet open in your territory; 2nd stage, $9.00 each); D is please write us. that of the smaller ones (S -M 255 and 256, $6.00 each). Note the marked ad- vantage over A, 13, and C- all standard eight and ten Silver- Marshall, Inc. dollar transformers under ..:}-- 848 W. Jackson Blvd., Chicago, U. S. A. equal conditions. w W .Please send me, free, the complete S-M Catalog; also sample copy of The Radiobuilder For enclosed in stamps, send nue the I following: .... (50e) Next 12 issues of The Radiobuilder ($1.00) Next 25 issues of The Radiobuilder Are you getting "The Radiobuilder ?" It's a little monthly magazine devoted to the S-M DATA SHEETS interests of all who build sets. The coupon at the left as follows, at 2c each: will bring you i ....No. 1. 670B, 670ABC Reservoir Power Units a sample copy. ....No. 2. 685 Public Address Unipac ....No. 3. 730. 731, 732 "Round-the-World" Short Wave Sets ....No. 4. 223, 225. 226, 255, 256. 251 Audio Trans- I formers SILVER- MARSHALL, Inc. ....No. 5. 720 Screen Grid Six Receiver ....No. 6. 740 "Coast-to-Coast" Screen Grid Four ....No. 7. 675ABC High -Voltage Power Supply and 676 Dynamic Speaker Amplifier 848 West Jackson Blvd., Chicago, U. S. A4 ....No. 8 Sargent- Rayment Seven Name - - - -Address Please say you Soso if in RADIO NEWS
www.americanradiohistory.com Radio News for November, 1928 407 LeaderBuild the of all designs for custom building The 1929 Screen Grid Laboratorj Super
Through four consecutive years of progress which have altered the whole technique of radio reception, the de- signs of this famous series have 'P!11,'II, steadily led the way. First the all - r wave feature -then the first "shielded" _ super for home construction -then the unit amplifier catacomb -all carefully copied by imitators as the Laboratory Receiver marched on to new improve - 710 Sargent -Rayment Seven ments. For 1929 are offered 3 screen - grid t.r.f. stages, ahead of a 65 kc. A precision laboratory instrument for the veteran fan -with single -dial tuning feature and separate stage verniers. There screen -grid amplifier -giving 10 kc. are four screen grid t.r.f. stages -five circuits in all are tuned sharpness, one -spot convenience, and by the single illuminated drum. One knob controls volume. Clough-audio -system tone quality. The Each circuit is individually shielded, by- passed, and isolated from all others by heavy plates integral with the satin-silver- price of complete parts is only $96 65. finished aluminum cabinet. Incorporates new Clough system S -M 700 cabinet extra. audios with output filter. The kit is $130.00 complete; or factory wired and tested, $175.00. New 720 Screen Grid Six Here is a set worthy in every way to 730 Short -Wave stand with factory products selling for sev- eral times the price. Build one and test Kit it -see how these three screen -grid r.f. stages cut past a powerful local and reach S -M 700 two -tone brown metal shielding All the thrills of code and out after feeble signals a thousand or two cabinet; fits S -M 720 and 740 sets, and voice reception from many thousand miles away on adjacent channels, also the 1929 Laboratory Super. Price, countries you can get night and deliver them with loud -speaker volume! with walnut- finished base, $9.25. after night with the new S -M The audio amplifier uses two Clough system 730 "Round-the-World" Four. stages. The complete kit is only $72.50 It has one screen -grid r.f. (two -tone metal shielding cabinet $9.25 ex- the 740. Entirely non- radiating-sharply stage, regenerative detector tra), or factory wired complete with cabinet selective to a 10 -15 kc. band- powerful far (non -radiating), and two of $102.00. beyond most factory -built G's, owing to per- the S -M Clough- system audio stages. Four plug-hi coils fit a fect utilization of a screen -grid t.r.f. tube - 5 -prong socket, accessible on top of the aluminum cabinet. The 740 -to- with all the matchless tone of the new complete 730 kit, including cabinet, is $51.00; the 731 Adapter, "Coast Coast" Four S -M audios. S -\I quantity production the same kit without the two audio stages, $36.00, converts The popular 4 -tube circuit, which multi- brings the complete kit price down to any set to long -distance short-wave reception. The 732 Essential plies distance range by regeneration, now $51.00, or for AC tubes $53.00. Cabinet Kit is only $16.50. applied to ideal coils, forms the basis of extra; see above. Power Amplifiers and B and ABC Power Supplies
S -M Unipac Power Amplifiers provide power am- information is given in our big new catalog. plification with 210 or 250 tubes, either single or For sets requiring 180 volts 1', type 6701 Reser- push -pull, and all (except 685) furnish B power (45, voir Power Unit (kit $40.50, wired $43.50) delivers 90, 135 volts) to the receiver. The 681 -210 (push - up to 60 m.a. with 22, 90, and 135 volts available. pull kit, $87.00, wired $102.00) is the most powerful besides 22, 90 variable. The 670:\BC ($43.0(, wired single -stage amplifier made. The 681 -250 at $81.50 $46.00) is similar but supplies also 1y, 2% and 5 ($96.50 wired) uses only one power tube instead volt AC filament voltage. Type 675ABC ($54.00, of two. Type 682 -210 (2 -stage push -pull, $102.00, wired $58.00) gives 450 maximum voltage instead wired $117.00) uses a 226 tube in a stage preceding of 180, and has an adapter which allows a 210 its push -pull super -power stage. Type 682-250 at or 250 type super-power tube to be used in the )6.50, (wired, $111.50) is similar, but with one power tube only in the last stage of any receiver at all. last stage. Type 685 ($125.00, wired $160.00) is the popular Public Address Type 676 ($49.00. wired $55.00) Dynamic Speaker Unipac, using three stages for microphone, radio, or record pick -ups to cover Amplifier amplifies the output of any receiver through crowds up to 10,000 people. a 250 tube, and supplies power to speaker field. S -M Reservoir Power Units give high output, and uniform reliable opera- Adding an S -NI 676 to any dynamic speaker requiring 90 to 120 volte ll.0 tion. All models use standard tubes (not included in price). Complete will improve tone and volume marvelously. We are National Distributors of S -M Products
We carry for your convenience a complete line of S -\I Radio Parts and Kits, including all the new Quick Clough audio transformers. Any of these can be shipped at once, as well as the new Unipacs, power supplies, audio transformers, and other parts. Our new catalog will be a revelation to you -use the coupon Courteous and get it now! LIBERAL DISCOUNTS TO THE TRADE. Service
1111 SETBUILDERS SUPPLY CO. ' 137 Romberg Bldg., Chicago, Ill. Send me at once. free. your new catalog SEthuilders Supply Co. listing S -\1 and other radin parts, cabinets, consoles. and accessories of highest quality ' Name 1
137 Romberg Building Add Tess 1 :: :; City State CHICAGO ILLINOIS om mo m mu m m m um m om m i Please say you saw it ist RADIO NE1VS
www.americanradiohistory.com 408 Radio News for November, 1928 4 NEW HI-Q RECEIVERS Custom -built To Any Pocketbook!
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Please say you saw it in RADIO NEWS www.americanradiohistory.com 409 Radio News for November, 1928 II KI) I Type BNK forreplac- ing the acid jan in Lill liti IJI LI Balkh` Type. N and K Trickle Barger. liCIIIILI{f_
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Type V-4 for re- placing the ree- tifieee in 6makea ofTrickle eharg- etc er. V e5ted iri t ase atot5e te ri°te >ass plri .we riri' 1 ri a 104 .io basffiet5be eli e tecteau5teít . p 1 e e eri e 1Eg taat. 0100/6se4aba5 beaceab gF, va se4 YÚg lyG`i 5to=a°Oe p Type M -16 for replac- 4 :;;e ing the rectifier. is eri 11 make. of ^A" tijb Eliminators d cAmpere chargers tt atá is. kae cba9 e4 a5 ito, ri a pt is the tie 4 tot, ` WOOL battea rie sec 5 r°t the<< ' G U,aratee ee d ,i t 5e 9°ps aae 0ps 11 e 1f i5ta ctrer'Wer Úrii s riaY° tb°5 íriOeá o ct'e the a Lte orita ;,err 01 d Balk t riY capt b°stz e not °r ee 8aSV"t a erit ° O lace pct5 iri . Type EBB for D ge4etY s oa e °t`y atg placing the BH COa of type Te es in °B" 1 5te asetb aria Eliminators ecti$ the t,o05es prit s betbe V911 '°f ,..te v 4 1aceety itbese atbo se4 éalopy ° t reetet 1 fos ztit5 ,es et toa-9.1.to ac .1-') o aea sece4 tep Y pt ooa bav Y° aSy G opss°5 ,e y1,tb O. Qe .:'`, 5 5°° 7 eQ° K, x: at t R Stet' o. Co.e ae1 Gbe v E'er/ Elkon Rec- l° tifier goes through t 1Vl°ti the.ecxactiogtest.. ót nY.RIri.
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www.americanradiohistory.com 410 Radio News for November, 1928
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www.americanradiohistory.com Editorial and General Offices, 230 Fifth Avenue. New York
Vol. 10 NOVEMBER, 1928 No. 5 Future Progress in Television By HUGO GERNSBACK WHEN broadcasting first started in 1921, a great deal be comparatively simple on the low -wave channels, the trouble here of speculation was rife as to what form the new art is that for some years. this must be a strictly experimental enter- was to take and what could he expected from it. For prise; because, even though the larger manufacturers were to put u long time, broadcasting was rather crude; and no one forth a combined television and broadcast set to operate on the had a definite idea what it was really all about. Only a good low waves, most of the listeners in the country would not be able deal later did paid advertising creep into the programs, and we to get such programs with their present sets. It would take years are still traveling along this road; either in the way of direct before such a change, from higher waves to lower waves, could be advertising, which seems to be on the decline, or the indirect form completely effected. of advertising, better known under the term of "sponsored" pro- At one time, it was thought that broadcasting on the low waves grams. But, even today, exactly what ultimate form commercial would be the one cure -all for every radio ill. Unfortunately, this broadcasting will take is not known, because changes are occurring is not the case, mainly because there is such a thing as "skip dis- continually while the art is progressing. tance." In large cities, it would be most difficult to receive the In television we are faced with a similar situation; for, ,just short waves and, on such wavelengths, few stations could be oper- at present, no one knows exactly what it is all about, or what ated successfully as locals. A short -wave broadcast station located television will really mean to the world at large. in New York or Chicago might be very powerful; yet no one in It is probably a foregone conclusion that, sooner or later, all the same city could get the broadcasts at all, due to the "skip - broadcast stations will be sending out television impulses in one distance" effect. 'l'he programs probably would come in much way or another. A number of stations -as, for instance, WGY and better two hundred miles away than twenty miles from the WY lt NY-are now broadcasting true television programs; while transmitter. others -such as 8XAV at Pittsburgh and 3XK at Washington, Of course, all of this discussion presupposes the dispelling of the D.C.-are broadcasting only "radio movies." The latter is not synchronization bugaboo which, at the present time, is the night- true television, according to my definition, because it is not "in- mare of all television experimenters. It is like a similar situation stantaneous sight at a distance," but rather "canned" sight. which prevailed in the early history of radio, away hack in the When WRNY went on a regular schedule, August 12 last, with coherer days, when it was almost impossible at times to decipher the television, a tremendous amount of interest was created imme- simple signals of the coherer, on account of static and other diately in business quarters. One leading department store sent troubles. Very often the signals became totally unrecognizable, its representative to the station, to find out if it were possible just as today, because of imperfect synchronization, the signals on to televise a fashion review which the store was sponsoring. The the television disc are often badly blurred and unrecognizable. So, management was told that, unfortunately, this is not as yet pos- just as in the old coherer and crystal days the amateur had to use sible, because the art has not progressed sufficiently; and, even his imagination in order to decipher the code messages, so the if it had, there are not yet enough television receivers to make present -day television experimenter must use his imagination to it worth while to put on such a review. recognize the visual images. But these, of course, are the usual Another advertiser wanted to know Whether the station would infantile diseases of a new art and will be speedily overcome as accept a contract to televise the images of articles of merchandise, others have been overcome in allied arts. interspersed with music and sales talk. _\ large publishing firm That we will require an entirely new technique of televising wanted merely to televise the cover of its latest book. .\ certain various subjects, is, of course, a foregone conclusion. Just as there advertising agency wished to build a program around a well -known is a "radio personality " -because certain voices and certain sounds brand of cigarettes, televising the actual cigarette package from broadcast well and others do not -so it will he in television. Not time to time. everything is fit for televising; this holds true of faces as well as Of course, most of these things are feasible today, in a way, of objects. 'l'he matter of the subject, is, of course, all important. and there is little doubt that, in the not- too -distant future, such It was quickly found at WRNY, that certain faces, for instance, commercial considerations will provide additional revenue for did not televise well at all. For instance, subjects with eye -glasses broadcast stations; hut, at this time, simply because there are are entirely hopeless, because of their reflection. Oil' skins broad- not enough television receivers in use. it would not be a paying cast better than dry skins. A woman with a large hat became a proposition for advertisers, and they will be told so by any honest total loss during transmission, while as woman with a small close- station management. Perhaps within six months, perhaps within fitting hat or none at all was far superior as as subject. a year, such commercial, "sponsored" television broadcasts will Also, if the subject is to" snuill -such as for instance, a small become an every -day occurrence and no one will think otherwise toy monkey -it becomes unrecognizable. But on the other hand, of them. if the subject is too large, the whole of it cannot he seen in the Of course, the serions difficulty with television today is that, at receiver, because of the small size of the image. Those received least on a single broadcast channel, we cannot have sound and at the present time are usually only about one and one -half by vision at the same time. No simultaneous broadcast is yet pos- one and one -quarter inches, hieing limited by the extent of the plate sible. 'l'he few stations that are now broadcasting television have of the neon lamp, and size of the rotating disc. trouble even to switch rapidly from "aural" programs -those which On the other hand, engineers are now beginning to remedy the can be heard -to "visual" programs. WRNY was perhaps the first condition last mentioned, through enlarging the image by means that managed to alternate the "aural" program quickly with the of special lenses. Most of the trouble seems to lie in the fact that, images that are hieing televised. Less than a fraction of a second at the present time, the neon tube does not give a sufficient amount now intervenes during the switching from television to regular of light to permit of enlarging the image; but this is also being broadcasting, but this is, of course. not the final solution. We overcome gradually. We probably will he soon using a multiplicity simply must have simultaneous television and "aural" broadcasting; of tubes, concentrating their light on one pant of the disc, and then but it is doubtful that we can have this on single broadcast chan- enlarging the received homage by means of lenses; or else improved nels for some time to come, unless an entirely new invention is tubes, giving greater light, will be developed. made, and this, as yet, does not seem to be in sight. It is quite possible that, before r year has passed, the 24 -inch It is, of course, quite possible to do it on two or more broadcast disc will have shrunk to a 5 -inch diameter and the much smaller channels; but then, again, at the receiving end, we would need and sharper resulting image will be enlarged and thrown on raj apparatus tuned in to diJrerent wavelengths, and that is evidently screen. Such television scenes will he much better in detail and rather difficult to incorporate into a single set, although not impos- more easily visible than the admittedly-crude images received at sible. While simultaneous television and "aural" broadcasting will present.
Hr. Hugo Gernsback speaks every Tuesday at 9.30 P. M. from Stations WRNY (326 meters) and 28AL (30.91 meters) on various radio and scientific subjects. ui www.americanradiohistory.com 412 Radio News for November, 1928
xçv°-YORK }'[I?,C'iTt,-...- rsLaoaftY STAB. bÁ\\ Lp rfTiF gNTO ^;,na IC_HERA elevision I PICTURES' Transmissions' ID MOVING Tltoit$naY': f/ÉIS/ Start at Statión ILi,DtoON THE ta `"e WRNY GO A, pCST . Real l tve --_ DI!~ Subjects, Not First RegRegula lt J Photos, .Used Begin /,S periments Used in E XT. WitIiY Will nano of Local $tat,oP the = ay oeaNnsNac Station. Into alNe.ktion° IC° rooters of -- ` the e.. Bróadcasttng Television RTaNT Tne krta o;., ^a1 d, AMAjfU ngn[ ws Il:rldp ,..,m Ever Attempted. I D' Cf WRNy Tme nN ndra D ^ynlmylemamma; emuPOfm Homes 11nn..rran, D a,Lk WI ateelpg Blneen. r, UmYF mt^b , °u e -tnev «BWlnB .,r! m ra
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www.americanradiohistory.com 413 Radio News for November, 1928
the successful tele- to be shown. Credit visor. As a matter of for the achievement TIMES. . MONDAY. AUGUST 13. YORK fact, the whole project of the feat is due to irr l'18 w a s sponsored by chief John Geloso, WRNY to Start Daily Television Broadcasts; RAmo NEWS, with Mr. engineer of the Pilot Geloso doing the actual Electric Manufacturing Radio Audience Will See Studio Artists experimental work. After Company, who worked performing successfully day and night for more in the laboratory, the of transmission as an intermittent high - than three months de- The first regular broadcasting televisor described in the over the radio pitched whirr, varying with the ac- signing, constructing and images by televisioa aforementioned a rtiel e from New York will begin tomorrow. tion before the transmitter. perfecting the televisor was moved on August 1.2 it was learned last night from Sta- Officers of. WRNY saw the images which is now in daily use from Brooklyn to the tion in the Hotel Roosevelt. -at a set installed in a private home WRNY and W2 \AL. WRNY WRNY transmitter house at WRNY, which is owned by 'The a few hundred. yards from the trans- s at Coytesville, N. .1., Some of Mr. Gelosti Radio News Magazine, has recently mitting station. preliminary experiments of equip- The television broadcasting sched- ,just across the Hudson completed the Installatiod River from New York. in the Pilot laboratories, broadcasting images, and uled to begin today will be made a ment for WRNY's usual programs, An experimental receiver in Brooklyn (New York yesterday it conducted its first ex- part of Mr. Gernsback said. After a singer was set up a quarter of a City) were described in broadcast- finished, his perimental or other entertainer has mile from the transmit- the September number of The broadcasting was done from or her face will be sent out over. the ItAnio NEWS, to which the the station's transmitting .plant at air by television. Thus the schedule Villa Richard. Coyfesville. N. J. The for the television will be the same as reader is referred. (Pages images sent consisted of the faces of for the regular broadcasting of this 221 -25G.) John Geloso, engineer of the Pilot station. Mr. Geloso received Electrical Company, and John Ma- Considerable experimenting already resca. chief engineer of WRNY. The has been made with television broad - Left, facsimile of clipping considerable assistance first broa .cast began at 6:43 P. M. pasting by other stations. For sortie from the New fork Times of from the technical staff and continued until 6:30. The second weeks C. Francis Jenkins has been August 13. 1928, recording by radio, news of the first success- of ltAnio NEWS, the mem- began at 11 P. M. transmitting silhouettes the There is no telling how many per- and other stations which have been ful television broadcasting bers of which furnished sons saw the Images, according to developing the television field are through WRNY. The state- many special television President of WGY, at Schenectady; WLEX. near ment in the headline, "Radio Hugo Gernsback. station parts and offered numer- WRNY. He estimated that there Boston, and WCFL, the labor audience will see the studio are about 2,000 sets in the metropoli- at Chicago. artists," was incorrect, how- ous suggestions as to the tan area equipped for television re- Mr. Gernsback said that WRNY ever, as explained in the ac- ruction and a rrange- of sets unequipped has received thousands of letter cornpaaying article. const ception. Owners broadcasting nient of the parts in for television heard the television asking for television
are shielded by copper mesh. Above, the author A general view of the Pilot televisor used at WRNY. The power- vised; they article is shown adjusting one of the ful arc light is in the square black can at the extreme right. The of the accompanying rheostats, while he is being "televised. ". A. edge of the scanning disc is risible above the top of the small amplifier control the photoelectric cells to the amplifier] table, which holds the audio amplifiers for the photoelectric cells, shielded cable runs from which are the large round objects faced by the subject being tele- on the table.
www.americanradiohistory.com 414 Radio News for November, 1928 ter, which is on the very edge of the Pali- John Geloso, seated be- sades cliffs, overlooking the entire island fore a complete broadcast - and television receiver, of Manhattan. Mrs. Geloso, wife of the viewing the television im- inventor, was the first subject televised. ages through the square Her husband, operating the receiver, tuned opening near the top of in the WRNY signals, adjusted the cabinet; the scanning the speed disc is about si.r inches of his scanning disc, and emitted a loud behind fhc front panel of whoop of joy when he recognized the clear the set. An experimen- image of his wife. These first images, about ter who is just starting in television one and a inches should not half square, were slightly build his apparatus into a streaked and had a tendency to move "out large cabinet like this of frame;" but they were comparable to one until he has first suc- average newspaper halftones in clarity. The ceeded in obtaining good results with a rough table broadcastü'g, it should be noted carefully, layout. This receiver is was done on the regular 326 -meter wave of the one used in the pub- WRNY, and required no changes in the lic demonstration at New regular Western Electric transmitter. York University. On August 14, Mr. Geloso moved the receiver to the home of Hugo Gernsback, the hall. Although no editor of RADIO NEWS, at 180 Riverside automatic system of Drive, New York; this location is about synchronizing the five miles in an air line from the WRNY transmitting and re- transmitter. With no opportunity for pre- ceiving discs had yet liminary trial or adjustment, Mr. Geloso been installed, Mr. turned on the set at tén o'clock in the eve- Geloso managed to ning and again succeeded in reproducing o b t a i n satisfactory the image of his wife, who was seated be- images of the sub- fore the televisor at Coytesville. This feat jects televised. The was especially noteworthy because the trans- images were not per- mitter and the receiver were operating on fect, but as Mr. Gems- entirely -separated power lines, and abso- back remarked in his lutely no means of synchronizing the scan- introductory address, ning discs was used. Because of the lack which was broadcast of perfect synchronization, the images by remote control wandered out of frame frequently; but for from the hall over six or seven seconds at a time they were WRNY previous to as clear as photographs. the television trans- mission, television is DEMONSTRATION INTERESTS PUBLIC now in the "spark - After this private exhibition, it was de- coil -and -coherer stage," and too much can- At present, it is not possible to broadcast cided to stage a public demonstration for not be expected of it for the present. the images of the artists who are perform- members of the radio trade and of the The first printed radio program listing ing in the WRNY studio in the Hotel press. The place chosen was Philosophy television transmissions as a regular feature Roosevelt, New York. Because of land -line Hall, at New York University, 181st Street appeared on the morning of that day; a problems the televisor must be close to the and in the University Avenue Borough of typical program, taken from the New York actual broadcast transmitter; so only the the Bronx (New York City) and the date, Times of August 21, is reproduced on the images of the WRNY operators and other August 21, 1928. This demonstration was first page of this article. All the WRNY persons at the transmitting room will be a marked success, having been attended by programs which have appeared since that broadcast, for some time to come. At the more than 600 people, all with agog inter- date have carried the exact time of each start of each transmission, a white card est, and many were unable to find room in television broadcast. bearing the letters WRNY in heavy, black letters is held before the televisor; so that the experimenter can make the required preliminary adjustment on his scanning disc to receive the transmitted image of a human television subject.
SCHEDULE NOW FOLLOWED Television images are broadcast simul- taneously by WRNY on 326 meters and by W2XAL on 30.91, the first five minutes of every hour that the stations are on the air. The complete schedule of television transmissions is as follows (cut this out and and save it, for it will be very useful when you make your own television receiver, as described elsewhere in this number), and all times are Eastern Standard.; add five hours for Greenwich time: Mondays: 7.00 to 7.05 a. m.; 8.00 to 8.05 a. ni.; 11.00 to 11.05 a. ni.; 12.00 (noon) to 12.05 p. m.; 2.00 to 2.05 p. m.; 3.00 to 3.03 p. m.; 4.00 to 4.05 p. m.; 5.00 to 5.0.5 p. m.; 6.00 to 6.05 p. ni.; 6.40 p. ni. to 7.00 p. m. (20- minute period). Tuesdays: 7.00 to 7.05 a. m.; 8.00 to 8.05 a. m.; 11.00 to 11.05 a. ni.; 12.00 (noon) to 12.05 p. m.; 7.00 to 7.05 p. m.; 8.00 to 8.0.5 p. m.; 9.00 to 9.05 p. m.; 10.00 to 10.05 p. m.; 11.00 to 11.05 p. m.; midnight to The lover half of the "works" of the receiver shown above. In the lower left corner is a 12.20 a. m. (20-minute period). three -stage resistance -coupled amplifier, with each stage individually shielded. In the right corner is a power-pack supplying "R" potential to the amplifier tubes. The broadcast tuner, of straight 'Wednesdays: 7.00 to 7.05 a. m.; 8.00 to T.R.F. design, is in a can behind the disc 8.05 a. m.; 11.00 to 11.05 a. m.; 12.00 (noon)
www.americanradiohistory.com Radio News for November, 1928 415
fl'hat the back of the is an opening about six inches square. These television machine shown cells (which are the subject of a separate on the opposite page looks like. The scanning disc, article on page 221 of the September num- driving motor and neon ber of RADIO NEws, previously mentioned) glow -tube occupy the top are completely shielded on all sides; the ex- half of the cabinet; while of their bulbs are covered the audio amplifier and posed portions power pack fill the bot- with copper mesh, while the wooden con- tom. The three cans at taining box is lined with sheet copper. The the feet of Mr. Geloso mesh acts as an electrical screen, but does (left) and his assistant, Frank T. Sullivan, are not keep out light. the shields for the audio- On the other side of the frame holding amplifier stages. The cells is a flat aluminum glow -lamp is in front of the photoelectric the scanning disc, di- scanning disc, 24 inches in diameter, pierced rectly under Mr. Stufi by a spiral of 48 holes. This rotates, at the can's right fist. Tite rate of 450 revolutions a minute, in front of broadcast tuner itself is which behind the scanning disc. a powerful electric arc, the light of passes through the holes and falls on the face of the subject. The side of the disc facing the arc is "masked" in such a manner short -wave set. RADIO that only one hole at a time passes light on NEWS has available a to the subject. As soon as one hole is swept number of. free blue- past the arc it runs behind the mask, just as prints of inexpensive the next hole of the spiral comes into view. short -wave receivers; As the holes are arranged in a spiral (each if you already do not being slightly nearer the center of the disc own a short -wave set, than the preceding one), a series of -48 drop us a postcard or separate rays of light, one directly under a letter and we will and following the other, flash across the send you a set of blue- subject's face (see page 222 of the Septem- prints free of cost. ber issue for a fuller explanation). These (Ask for blueprint rays of light are reflected into the photo- No. 58, if in doubt.) electric cells, which produce electrical cur- rents corresponding in intensity to the reflection from the light and dark SIMPLICITY OF THE amount of of skin and hair; this action TRANSMITTER portions the may be compared to that of a microphone in The Pilot televisor translating the tones of the voice into elec- now in use at WItNY trical vibrations. The impulses generated in construction, as by the cells are amplified by a bank of to 12.05 p. m.; 2.00 to 2.05 p. im ; 3.00 to is comparatively simple be seen specially -shielded resistance-coupled ampli- 3.05 p. in.; 4.00 to 4.05 p. tn.; 5.00 to 5.05 television apparatus goes. As can of page 413 fiers, which in turn feed the modulator tubes p. ni.; 6.00 to 6.05 p. m.; 7.00 to 7.05 p. ni.; from the picture at the bottom units: a of the broadcast transmitters. The latter 8.00 to 8.05 p. m. it consists of four fundamental source of light (an arc lamp), a scanning send out signals which are plainly audible Thursdays: 7.00 to 7.05 a. m.; 8.00 to 8.05 326 disc, a nest of three large photoelectric in any ordinary broadcast set tuned to nn.; 11.00 to 11.05 a. In.; 12.00 (noon) to a. cells, and an amplifier for the output of meters, or in any short -wave set adjusted in. 12.05 p. the latter. to 30.91 meters- within reception range of Friday.: 7.00 to 7.05 a. m.; 8.00 to 8.05 The person to be televised sits in a cloth - the station -as a peculiar noise with a fun- p. m.; 11.00 to 11.05 a. tn.; 12.00 (noon) to covered booth facing the photoelectric cells, damentally low -pitched note, mingled with 12.0.5 p. ni.; 2.00 to 2.05 p. in.; 3.00 to 3.05 which are arranged in a triangle' in a shriller ones, depending on the character of p. ni.; 4.00 to -4.05 p. nt.; 5.00 to 5.05 p. m.: wooden frame, through the center of which the image. (Continued on page 4.90) 6.00 to 6.05 p. nn.; 7.00 to 7.05 p. w.; 8.00 to 8.05 p. In.; 9.00 to 9.05 p. m.; 10.00 to 10.05 p. nt. Safurdaya: 7.00 to 7.05 a. w.; 8.00 to S.05 a. m.; 11.00 to 11.05 a. nt.; 12.00 (noon) to 12.05 p. tu.; :3.40 to 4.00 p. m. (20- minute period); 7.00 to 7.05 p. nt.; 8.00 to 8.05 p. nt.; 9.00 to 9.05 p. m. Sundays: 7.00 to 7.05 a. in.; 8.00 to 8.05 a. m.; 11.00 to 11.0.5 a. nn.; 12.00 (noon) to 12.05 p. tn.; 2.00 to 2.05 p. m. ; 3.00 to 3.05 IL HI.; 4.00 to 4.05 p. m.; 5.00 to 5.05 p. m. Most of the periods specified are of only live: minutes duration, but it will be noted that there are also three twenty -minute per- iods, one each on Monday, Tuesday and Saturday. These longer transmissions en- able the experimenter to adjust his receiv- ing apparatus more carefully and to receive a greater percentage of perfect images than the shorter live- ndoute broadcasts allow. An announcer breaks in several tintes, (luring each twenty-minute period, to tell what is being broadcast. WCRNY now tele- vises the following: faces of living people, the Wit NY placard previously mentioned. a moving toy monkey, and a moving "roly- poly man." Those living in the vicinity of New York may tune in WRNY's regular 32G -meter wave on their regular broadcast receivers; A close -up of the scanning machinery; the synchronous A.C. motor, revolving at 1800 r.p.m., turns outside of the New York the disc through a 1:4 reduction worm gear. The neon glose -lamp is supported on an adjustable experimenters stand immediately behind (here seen in front of) the scanting disc. Tite disc is 24 inches in local area can do best by using a simply diameter, has a spiral of 48 holes, and turns "counterclockwise" at 450 r.p.m.
www.americanradiohistory.com 416 Radio News for November, 1928
-_ . ****-44...
PP Nviovirs REGULAR PROGVAMS ON THE S I1 O RT WAVES GROIIISEG
:(bore: 1)r. Frank Conrail, research engineer of the Westinghouse Company, s(ondiag behind his "re.,lio- morie" transmitter.
ON August 8 the Westinghouse Elec- . Tenkins system, which works very well and shadow in the same arrangement which they tric and :Manufacturing Company which is now on the air, on short waves, occupy in the subject photographed. In demonstrated a system of "radio three times a week. screening a motion picture, a roll of film is movies" to members of the press 'l'he statement issued by the Westing- operated at a speed which sends and a group sixteen of distinguished radio men at house company at the time of the demon- pictures a second before a projecting station KDKA, bean East Pittsburgh, Pa. The stration promised that regular "radio - of light. Because of the structure of the demonstration was very successful and con- movie" transmissions through KDKA would human eye, if pictures follow each other in vincing, but the daily newspapers which commence "within a few weeks," although a regular series at the rate of eight or more mistakenly heralded it as the "first trans- no data concerning wavelength or details per second, :.lssion the eye sees a single moving of motion pictures through the air of the transmitting system were given. The picture. To broadcast the "radio movies" i.1 the history of the world," either over - New York office of the company yielded the requires all this, with l:oked the addition that the or were in entire ignorance of the more definite information that one of spots of light must be transformed into work which C. Francis Jenkins had been KDKA's short-wave channels will he used. electrical vibrations, which are in doing turn in Washington for months before the This will be good news to thousands of radio caused to modulate a radio "wave." In Pittsburgh showing; as they gave him no experimenters all over the world, as KDKA the reception of the pictures, the process is credit at all for his own previous success- is the most consistent and reliable short- reversed. The electrical energy represent- ful broadcasting of "movies." RADIO NEWS wave broadcaster on the air today. ing the radio "wave" is picked up, amplified, wishes to straighten out this matter merely In the demonstration of August 8, the demodulated, and the electrical vibrations as a matter of historical interest, and not "radio- movie" signals traversed a distance are returned to the forni of lights and to disparage in any way the very admirable of abòut four miles: two miles over wires shadows, which, when viewed by the human achievements of the Westinghouse research from the television laboratory to the broad- eye, constitute the "radio movie." engineers. cast station proper, two miles away, and In the first step of the transmitting The Jenkins "radio- movie" apparatus was two miles back to the same laboratory by process, a sharp beam of light traverses the subject each of the front -cover illustration radio. They could just as well have been picture or "frame" on the roll of film, in of Rimo NEWS for August, 1928, and was sent a greater distance; but the object was parallel paths, 60 times. A sixteenth of a c:escribed in great detail in a three -page to show the operation of the whole system, second, the length of time each "frame" is article in that number. A member of the both transmitter and receiver, to the as- kept in view, is required for this editorial scanning. staff who made a trip from sembled guests. A sixty -line picture is as clear as the usual New York to Washington, for the spe- good newspaper halftone. cial purpose METHODS AND APPARATUS of examining the equipment, The sharp beam of light is produced by reported his observations in that . article. As explained by the Westinghouse engi- the interposition of a scanning disc which The reader who is interested in the general neers, the operation of the "radio- movie" has a series of minute square holes arranged subject of animated radio telephotography system is as follows: in a circle near its rim. This type of scan- (the correct designation of "radio movies ") Photography in its simplest form consists ning disc should be distinguished from the is referred to this for the details of the ,of the reproduction of spots of light and usual television disc in which the holes arr
www.americanradiohistory.com Radio News for November, 1928 417
of the received images in this article; but, as soon as the information is forthcoming, RADIO News will publish it. The accompanying illustrations give a good idea of the construction of the trans- mitting apparatus; the picture bearing title shows Dr. Conrad standing behind the ma- chine, while the lettered picture on this page shows a close -up of the parts. L1 is a powerful lens which concentrates the light from an incandescent lamp (contained in the square -shaped can in front of Dr. Con - rad's arm in the title cut). The light beam passes through the square holes of the scan- ning disc D and, after coming out on the other side of the disc, is further concen- trated by a second lens, 1.2. The tiny "pin- head" beam from this lens sweeps across and through the film F, which is moved boi- zontally from one reel to the other by a suitable ratchet mechanism which engages the slots in its sides. The photoelectric cell P is contained in a shield can, located be- tween the film reels. 'l'he construction of the scanning disc may furnish home television experimenters with an idea. The minute scanning holes are drilled, not directly through the disc itself, Dr. Conrad at his "radio -movie" apparatus. The square can next to his right hand but through little individual metal tabs a powerful lamp which produces the light used for "scanning" the contains which movie film. Pictures of the receiver are not get available. are adjustable and attached to the disc. Of course, a circle of larger holes is first drilled into the disc, and these allow the light from the tiny square holes to pass arranged in a spiral. A circle of holes is dim as fast as the current changes, and its through. used in the Westinghouse system, and not a light at any instant is in proportion to the spiral; because the movie filet itself is stead- light that the electric eye "sees" in the same The Westinghouse company is definitely the manufacture of commer- ily moving past the beams of light, and thus instant at the transmitter. To return the contemplating cial -movie" receivers, according to its the whole surface of the filar is scanned. dots of light to their original pattern, a re- "radio when these are ready they In a television system such as WIRNY uses, volving scanning disc is used. This disc announcement; the subject (corresponding to the pictures must, of necessity, contain its holes in a will be sold through the Radio Corporation of America. A Westinghouse official, when on the film) is stafionaay; so the scanning spiral arrangement, in order to build up questioned by RADIO NEWS, stated that no holes must be arranged spirally in order to the necessary 60 lines corresponding to the in idea when the the suh,ject completely. scanning lines at the transmitter; and the one the company has any cover experi- 'l'he Westinghouse disc is so arranged lamp is mounted, presumably, at the top, instruments will be ready, as the been com- all_ light is excluded from the filmy ex- in order to obtain proper scanning of the mental work on them has not yet that done. cept that which conies through the square reproduced image. pleted and much remains to be one of holes. 'l'he disc turns very fast and, as it According to the statement released by At present station 8XAV, using turns, flings the beaus of light across each the Westinghouse company, the use of a the several short -wave transmitters at East frame from top to bottom (side to side of "mercury arc" lamp permits the received Pittsburgh, is transmitting these "radio the picture), so that the whole is "scanned." images to be projected upon a ground -glass movies," though as yet not on any regular receivers 'l'he beaus of light passing through the screen. As the company is decidedly reti- schedule. Owners of short -wave pick up the signals if they film falls into an "electric eye," or light - cent about divulging the details of the re- can probably sensitive cell, which is not unlike an over- ceiver, we cannot give the exact dimensions will tune to 62.5 meters. sized incandescent lamp in external appear- ance. Within the cell is a thin coating of caesium, a rare "alkaline" metal. The amount of light falling on this cell de- termines the amount of current passing through it the result is that each individual beaus of light produces an electrical impulse which varies in intensity directly in pro- portion to the amount of light (or shade) at the point of the film through which it is passing. The impulses are amplified and then conducted to the broadcast tsaaismitter. According to Dr. Frank Conrad, who de- signed the Westinghouse "radio- movie" ap- paratus, the frequency of the picture im- pulses thus obtained ranges from 500 to about 60,000 cycles. The width of this band makes the application of the present system to the regular broadcast band out of the question; on the short waves, of course, transmission can be handled more easily.
TILE RECEIVER 'l'he receiving end of the system appears to be practically identical with other exist- ing disc systems. The received impulses are detected and amplified and then led to a mercury -vapor lamp, which corresponds to A close -up of the "radio-movie" transmitter: LI, lens concentrating a powerful sharp "pinpoint" the neon -gas glow -lamp of less expensive beam of light on the scanning disc D; L2, second lens producing receivers. The mercury lamp goes bright or of light on the floe F. P is the photoelectric cell.
www.americanradiohistory.com 418 Radio News for November, 1928
SCANNING SCANNING DISC
1 MOTOR - MOTOR FIG. t A
SPOTLIGHTS VIEWING DEVICE HEAD OF PERSON NEON TUBE LENSES BEING TRANSMITTED E ( I -
PHOTOELECTRIC CELLS t OBSERVER'S HEAD
FIG. t
TRANSMITTER RECEIVER
The "Stereoscopic" transmitter is shown in diagram form at the left, and the receiver at the right. The disc (Fig. 1A) scans two distinct images, one for each eye. How "Stereoscopic" Television Is Shown John L. Baird Produces Moving Images Which Are Given the Appearance of Solidity J By R. F. Tiltman
THE last few months have witnessed out -of- doors. This was followed almost im- time on August 10 in the Baird laboratories spectacular advances in television. mediately by transmission of objects in in Long Acre, before an audience of scien- In June, John L. Baird demonstrated natural colors, as described in RADIO NEWS tists and representatives of the press. before Professor Fleming and other for October; and now, immediately on top distinguished scientists and press represen- of all this, comes the demonstration of THE PRINCIPLE OF THE STEREOSCOPE tatives the transmissions of persons illumi- stereoscopic television. Stereoscopic television gives the image nated only by ordinary daylight, thus re- Television images in, apparently, three the appearance of solidity or depth, so that moving television from the laboratory to the dimelisions were demonstrated for the first it does not look like a flat picture, but like an actual living object. The stereoscope does the same thing for photography and, in explaining stereoscopic television, we must first of all examine the principles of stereoscopy. The appearance of solidity or depth which we have arises from the fact that we view the exterior world through two eyes, each of which sees the scene from a slightly different viewpoint. The mind com- bines these two different images into one, and it is the blending of the left -eye and right -eye images that gives the impression of depth. In the stereoscope, with which we are all familiar, two photographs, taken by cameras separated a distance equal to or greater than the distance between the two eyes, are placed side by side in a viewing device con- sisting of two prisms, so arranged that on looking through the prisms the images are converged and made to overlap. The ex- traordinary result is then obtained that, in- In this picture of the Baird transmitter, the photoelectric cells are in the box at the stead of our seeing two overlapping images, right: S, light- source; D, scanning disc; L, lens; C, cloth covering cells; the mind combines these two dissimilar pic- P, subject undergoing -television. tures into one composite view; and this
www.americanradiohistory.com Radio. News for November, 1928 41 composite view does not appear as a flat 3fr. Baird (right) is here shown demonstrating his "stere- photograph, but gives the observer the im- ovision receiver. The familiar eyepiece with its twin pression that he is looking into the actual prisms is at the right of the apparatus; the Baird receivers scene itself. The illusion is very striking. "frame" the image at the side of the scanning disc instead of the top. The microphone in front of this receiver is room. A DOUBLE TELEVISION IMAGE for communication with the transmitting By applying the stereoscopic principle to television, it has now become possible to Photos © Photo press. transmit television images with all the ap- pearance of depth and solidity; and, by a further combination of colored television with stereoscopic television, the complete illusion of images in natural colors, and with depth and solidity becomes possible. All this has recently been demonstrated in the Baird laboratories. The transmitting apparatus consists of a disc, perforated as shown in Fig. lA with two spirals; the first spiral being arranged round one -half of the circumference of the disc. The other spiral occupies the other semi -circumference, about four inches fur- ther in; the separation corresponds to the distance between the eyes of a human being. Behind the disc, when it is mounted in the transmitter, as shown at the left of Fig. 1, is arranged an intense source of light. In front of the disc, and in line with the light - source, a lens is placed in such relation to the disc that a spot of transmitted light is caused to traverse the object. This arrange- ment is duplicated, so that each spiral has its lens and light- source; thus, two light eye, the other to the object as seen by the scope, but rely upon the naked eye; in much spots traverse the object alternately, and left eye. These images are then viewed the same way as a user of the microscope two images are transmitted, one for the through a stereoscopic viewing device, con- keeps both eyes open, but still sees only the left eye and one correspondingly for the sisting of two prisms, which cause the object under the microscope. The eye which right eye. images to converge and blend into one, just is not looking through the microscope is At the receiving station a similar device as in the ordinary stereoscope for photo- .sub- conhciously rendered, as it were, blind. is used, as indicated at the right of Fig 1. graph viewing. Professor Cheshire, lately president of A disc with the same arrangement of holes It may be of interest to note that this the British Optical Society, who was pres- runs exactly in step with the transmitting stereoscopic viewing device is really un- ent at these demonstrations, stated that a disc; but behind the receiving disc is a neon necessary, and those who have the knack man sitting at the transmitter was very tube, arranged as in ordinary television. can make the images blend without the use clearly seen on the receiver in another labora- The neon tube, however, covers both spirals of prisms; merely by looking fixedly at the tory in the same building, in perfect re- and illuminates them alternately; so that images, and concentrating, by an act of will, lief, showing the facial delineation and ex- on the receiving screen appear two images the left eye upon the image at the left and pression; and declared also that these ex- side by side, and separated by approxi- the right eye upon the other. This is, in periments promise considerable development mately half an inch. One of these corre- fact, the method used by most experts in and importance in their practical applica- sponds to the object as seen by the right stereoscopy. They seldom use the stereo- tion.
Televentures, Telewitticisms and the Televocabulary WITH the first public demonstration of bulb to use to give perfect reception to in' in the heyday of home -set building. The of successful television, on however Douglas Fairbanks." construction of a television apparatus in the modest a scale, the press has taken "Probable complaint to radio service sta- garret demands an equipment and a skill up the task, in a spirit of humor blended tion: 'This set you sent me is no good. I beyond the average amateur. At best the with seriousness, of accustoming itself and can't get Famous Players or Metro - 'televised' images must be coarse and its public to the new conditions which must Goldwyn.'" barely recognizable, with an almost uncon- be met. As with the telegraph, the tele- "The owner of a two -bulb set soon will trollable tendency to shift from the screen. phone, the electric light, the moving pic- be able to get everything a picture house It must not be forgotten that the brilliant ture, the airplane and the radio broadcast can offer except the ultra-polite ushers, the demonstrations by the American Telephone system, all of which have successively lobby statuary and the liar outside the box and Telegraph Company were possible only emerged from the laboratory in an unper- office who tells you there are 'plenty of with the aid of a score of trained engineers fected condition, to develop into public utili- good seats inside.'" who knew their technical roles as well as ties of the most commonplace nature, so it "The radio is making it more and more the actors of a theatrical company know is to be with television. unnecessary to leave home for diversion. their lines. 'Fading,' one of the bugbears A certain amount of gibing at the pres- All that is needed now is announcement of radio, causes unpleasant distortion of the ent unperfected nature of the invention al- from some genius that lie has found a way image, and so does poor synchronization of ternates with half- serious prophecy of what for the family to make its week -end auto- the transmitting and receiving apparatus. it will be when it has reached its fullest mobile trip by radio and for all men to go Radiatioh of faces on a lavish scale is at growth; in many cases, no doubt, the re- to work by television." present a technical impossibility because ality will outrun the joke. each television transmitter requires an ex- "Moving pictures by radio," remarks H. I. THE INVENTOR'S CHANCE cessively wide channel in an ether already Phillips in "The Sun Dial" of the New York More conservatively and sedately, as ever overcrowded. Sun, "are soon to be a household commodity. its editorial wont, the New York Times "Clearly, the development of television The time may come when every radio set looks at the present experimental stage of belongs to the engineer. British and Ger- will carry a chart giving Charlie Chaplin's the art: man authorities view his task with misgiv- wavelength, the number of kilocycles it "Probably the tinkering televisionary will ings and even doubt if it will be possible takes to get Toni Mix and the right type never be as ubiquitous as was the 'listener- (Continued on page 466)
www.americanradiohistory.com 420 Radio News for November, 1928 The Jenkins "Radio -Movie" Reception Methods Some Operating Hints Which Will Be Valuable to Television Experimenters in Constructing Their Receiving Apparatus
REGULAR schedules of radio movies Later, it is promised, "halftone" or knowledged. I expect as great a surprise have been established by the Jenkins shaded motion pictures will be sent, when when the amateur takes up this new work. Laboratories, 1519 Connecticut Avenue, it is to be expected that the technique of "This is the beginning of a new industry Washington, on 46.72 meters (6,420 kilo- the receiving amateurs has improved. For -a new form of radio entertainment. With cycles) with 48 -line pictures. They run from the present, a gradual progression in the these motion- picture broadcasts we are hop- 8:00 to 9:00 p. m., E. S. T., on Monday, complexity of the images is being at- ing to contribute to its rapid development. Wednesday and Friday nights (or 0100 to tempted; the earliest film transmitted was Your reports on our signal strength, fading, 0200 GMT on Tuesday, Thursday and only that of a dancing figure, comparable echo images and quality of picture recep- Saturday mornings). When a sufficient num- with the "zoetrope" toys, which were the tion will greatly help. ber of amateurs have shown that they are in forerunner of the moving picture. Elaborate "Ultimately, this pantomine story-teller position to receive these, the broadcasts will subjects and later actual stories followed. will come to all our firesides as a fascinat- be made nightly. Preliminary announce- The broadcasting has been in charge of ing teacher and entertainer, without lan- ments are made from the station, whose Stuart Jenks and Paul Tomsen. call is 3XK, in guage; Literacy or age limitation; a visitor both code and phone. At "We the end of each picture the have disaivered," says Mr. Jenkins' to the homestead with photoplays, the letters END announcement, are shown, to indicate that it is time to "that stories in silhouette opera, and a direct vision of world activi- are as entertaining as movie return to reception by ear. cartoons in the ties, without the hindrance of muddy roads, theater; plus, also, the The transmitting system, which was de- appeal of the mys- or snow blockades." tery of movies by radio. scribed in RADIO NEWS for August ( "Radio While the radio movies are vision only Movies and Television for the home," page -hand, in BEGINNING A NEW INDUSTRY at second contrast to the true tele- 116) operates to send silhouette images, vision, the mechanism reproducing them is which are printed on standard moving -pic- "Picture subjects and picture stories in the same as that required for television; ture film. Scanning these with a very small silhouette are easier for the amateur to pick and it is quite possible that they will beam of intense light gives an impulse much up at first; and obviously the width of the find places in television schedules even after sharper than that obtained in televising picture- frequency band is very much less the perfection of television, even more so faces, clothing, etc., by reflected light. The and, therefore, greater latitude is available. than mechanically-reproduced music does in images are sent out at the rate of 15 a sec- "Our immediate interest in the broadcast- the radio broadcast schedules of the world ond, or 900 per minute. ing of radio movies is to enable the amateurs today. For instance, many events of great While the Jenkins laboratory -model re- of America and Canada to become familiar interest in the world take place at hours ceiver, described in the article above men- with the principles involved, in the belief when the inhabitants of distant lands are tioned, is of very high -grade workmanship, that they will assist in this development. busy or sleeping; and their repetition by the and too complicated for home construction, 'l'he American radio amateur has shown his radio movies a few hours later, with or the television experimenter will find it pos- remarkable cleverness in the development of without an accompanying sound broadcast, sible to receive the radio movies on a 48 -hole `worthless frequencies' below the 200 -meter will be a desirable news service. lisc running at 900 revolutions per minute. band, as is now generally and officially ac- (Continued on page 492)
NEON NEON -TUBE TUBE TUBE SOCKET FRAME FRAME FRICTION DRIVE IDLE DISC DISC NEON TUBE IDLE MOTOR MOTOR DRIVING MOTOR DRIVING MOTOR BRACKET
SLOT
TRACKS
DRIVING TOP VIEW THREADED SIDE FRONT VIEW BOTTOM OF SIDE VIEW MOTOR ROD SUPPORTS FRAME
1" STRIP ABOUT NUTS SOLDERED NUT SOLDERED 12" LONG TO ROD TO L BRASS L I- RUBBER KNOB THICK 1" STRIP SET DISCS SLIDE 1=
BRASS L WOOD SCREW FOR STOP OF RIGHT END THREADED TIGHTENING SUDE FRAMEWORK OF SLIDE BRASS ROD FRAMEWORK MOTOR SHAFT; DETAILS OF SLIDE AND TRACKS DETAILS OF DETAILS OF ADJUSTING MECHANISM FRICTION DRIVE
The three upper drawings show the arrangement of the parts of an motor. In assembling the adjusting mechanism, drill out: the upright 'excellent television or "radio- movie" receiver; the support for the arms of the L- shaped brackets so that the threaded brass,rod will re- disc may be an idle motor or a small polishing head. Mount the volve in them easily. Once the proper position for the slide has been neon tube so that it is not affected by the vibration of the driving found, turn in the wood- screw, so that the motor will not "walk."
www.americanradiohistory.com Radia News for November, 1928 421 Successful DX Work Marks "Radio- Movie" Transmissions nADIO experimenters who are contem- had no trouble in using a 'B' supply unit for plating the construction of tele- both the glow -lamp and the receiving tubes vision or "radio-movie" receivers will on this short wave." be interested to learn of the splen- THE RECEIVING APPARATUS by did reception that is being obtained That Mr. Millen finds it possible to use the scan- others who have already assembled a transformer-coupled amplifier for satis- ap- ning machinery and its supplementary factory reception of images is rather sur- should paratus. Such successful reception prising, as practically all television engi- encourage hesitant constructors to proceed neers have considered resistance coúpling without delay, so with their own receivers to be necessary, because of its compara- thrill that they also will experience the great tively smoother amplifying characteristics. of "seeing by radio." Mr. Millen s transformers are exceptionally en- One of the most active television large and heavy ones, which may account for in the is James Millen, of thusiasts East his success with them. Malden, Mass. Although Mr. Millen is a A picture of the amplifier is shown be- in, the employ professional radio engineer low; it comprises two straight amplifier of a large manufacturing concern, he is an stages and one of push -pull. Resistance - at heart and spends a great amateur dabbler coupled audio amplifiers will, in most cases, deal of time in his own home laboratory, give more reliable images. However, the of are shown on this page. pictures which experimenter owning a high -grade trans- a simple television receiver He constructed former amplifier should by all means try using a -four -inch disc, a neon -gas twenty his available apparatus first, before spend- glow -lamp and an -speed motor, adjustable ing money on additional equipment. good luck in receiv- and has had unusually The general layout of the apparatus em- movies" on 46.7 ing the Jenkins "radio ployed appears below. The clock-like in- meters. .11r. James Millen strument on the right side of the scanning - A received from him lately by letter disc box is a speed indicator; this is a RADIO News reads as follows: was written at the end of August.- EDITOn), rather expensive device but is, of course, a when reception on the broadcast band was great help in adjusting the speed of the FIVE -HUNDRED-MILE RECEPTION almost impossible, we received the entire disc's driving motor properly. "You will, no doubt he interested to know silhouette broadcast, and had no difficulty The short-wave receiver used by Mr. Mil- that for the past week I have been able to in following the movements of the girl len was assembled from a commercial kit, receive all of the Jenkins 46.7 -meter broad- bouncing the ball and seeing the ball itself but experimenters desiring to build one like casts on a rather simple outfit built up at bounce up and down. it are invited to write for RADIO News Free home in one evening. While the pictures are "The outfit comprises the standard Na- Blueprint No. 62. This blueprint shows the not as good as those .Jenkins himself demon- tional short -wave kit, a three -stage trans - construction of a receiver of practically strated in Washington, I think they are very former- coupled amplifier operated from a identical design; this employs a screen -grid fine when one considers the iliaance involved 'B' socket -power unit, and the scanning de- tube as an R.F. amplifier, and is a very fine -somewhere around 500 miles. During a vice. The amplifier used was from a broad- all -rood short -wave outfit. Remember, the local thunderstorm last Friday (This letter cast set, with one 'haywire' stage ahead. I blueprint is free for the asking.
At the right: The "breadboard" Below is a rear view of Mr. three -stage transformer - coupled Jlillen's scanning apparatus. amplifier used by Mr. Millen for The neon -.gas glow -lamp is his reception of the Jenkins mounted upright on the narrow "radio movies." Below: A gen- upper shelf behind the scanning eral view of the television re. disc. The scanning disc's driving triver. The short -wave tuner is motor is an alternating -current the apearatu s with the small machine of the condenser type. panel, the scanning apparatus designed especially for television is in the box on Nue right. The work. This receiver is, it will clock -like instrument connected be seen, very much like the one to the scanting disc is a speed described on page 422 of this indicator. issue.
i
www.americanradiohistory.com 422 Radio News for November, 1924 How to Make Your Own Television Receiver
IN order to pick up and reproduce the television images now being broadcast by WRNY and W2XAL, you need only a modest assembly of instruments, some of which you probably already have on hand, and some of which you will have to buy. First, since the television images are transmitted simultaneously on 326 and 30.91 meters, by WRNY and W2XAL, respec- tively-, you need either a regular broadcast tuner or a short -wave tuner. If you live in or near New York, and obtain satisfac- tory loud -speaker results from the regular WRNY transmissions, all you require is a separate audio -amplifier of the resistance - coupled type, and the scanning mechanism, to be described later. If you are already using a resistance -coupled amplifier, as ninny radio fans are, you will need only the scanning apparatus. If you cannot hear WRNY's 326 -meter wave very well, the best thing to do is to H. Gernsback, Editor of RADIO News, receiving the television broadcasts from WRNY at his home in New York City, with the install a in simple apparatus described in this article. For purposes of the short -wave set, order to pick up test, the neon tube and loud speaker were connected in series temporarily, with successful the 30.91 -meter wave of W2XAL. You operation simultaneously. will require the audio amplifier also, how- ever. Happily, short -wave receivers are If you are able to use your regular broad- ing reproduced, these are not very notice- very inexpensive and can be built very cast receiver for WRNY, you will not use able to the ear. When television images easily, so you should assemble one without for television reception the present audio are being reproduced, even the slightest ir- delay. It will enable you to pick up, not amplifier if it is of the transformer type. regularity will cause the already crude only W2XAL's television signals, but also Simply run a wire from the plate (P) post images to break up and assume peculiar the "radio- movies" of station 3XK (using of the detector tube to the top input post shapes. The general experience of television the Jenkins system), and musical programs of the resistance -coupled amplifier shown in experimenters has been that resistance - from short -wave broadcast stations in many Figs. i and 3, unhook the "B+Det" wire coupled amplifiers are more satisfactory for parts of the world. We can particularly running to the power unit or "B" batteries, both television transmitters and receivers, recommend the set described in the RADIO and bring this saine wire to the other input at least in this stage of the art. NEws Free Blueprint No. 62. This uses an post of the audio amplifier instead. With above statements R.F. amplifying stage, has only one tuning this arrangement, the detector will be feed- should not be inter- control, and costs very little to assemble. If ing directly into the resistance- coupled preted as a condemnation of the trans- amplifier. you do not already own a short -wave re- amplifier. former There has long been rag- ceiver, just drop us a card and we will ing in technical circles a controversy over send you Blueprint No. 62 free of charge. RANGE OF FREQUENCIES the respective merits of the transformer and In making this receiver, do not install the "Why can't a regular transformer ampli- resistance systems for the amplification of voice single stage of audio amplification. Leave fier be used? Why is a resistance ampli- and musical signals, with the radio out the audio transformer and the third fier necessary ?" you may ask. experts evenly divided between the two tube, and simply provide two binding posts The answer is that resistance- coupled am- camps. At the present time, however, it is for the wires that are shown connected to plifiers amplify audio -frequency impulses easier to get good pictures from the latter system, we the primary posts of this transformer. The ranging from 50 to 5,000 cycles snore uni- so recommend resistance coup- ling. detector is then easily connected to an ex- than do most transformer -coupled However, it is entirely possible to formly obtain ternal resistance -coupled audio amplifier. amplifiers. The television impulses broad- satisfactory results from a high - cast by WRNY - quality transformer arrangement; witness W2XAL and others the work being done by James Millen, of cover this frequency Malden, Mass., whose experiments are de- range, and they must scribed briefly on page 421 of this issue. be reproduced faith- A good three -stage resistance-coupled am- plifier can easily be assembled on a wooden .,,.,,,,,,.,.,,,,,,,,. board, about five -inches wide and twelve A commercial three -stage inches long. A completely- assembled one amplifier which may be can be bought for about ten dollars, but a purchased already assem- home -made one will bled is convenient and not cost so much. After compact. The 171 -type you finish it, you will have a fine ampli- tube in the output is best fier, not only for television impulses, but suited to the character- for regular broadcast programs as well. istics of the neon tube. DESIGN OF AN AMPLIFIER fully at the receiving S -oil will need the following parts, ar- end, without emphasis ranged and connected as shown in Figs. 1 on any particular reg- and 3: a wooden baseboard; three UX -type ister, in order to cre- tube sockets, V1, V2, V3; three 4-ampere ate a recognizable filament ballast resistors, R4; two double - image. Most, transformer amplifiers possess resistor mountings; four 0.5 -mf. fixed con- slight irregularities in their response char- densers of the by -pass type, C; one 1.0 -mf. acteristics but, when voice or music is be- condenser, Cl; a special high -value grid
www.americanradiohistory.com Radio News for November, 1928 423
TO PLATE OF 180 -VOLT NEON DETECTOR e "B" BATTERY TUBE TUBE 'I V3 V1 V2 II o 0 _L DISC eL2 R1 R3 - MOTOR R3 0 R5 - R4 TO "B'+ al F i SWITCH DETECTOR r o o R6 DOUBLE - SWITCH 1 MF. .ig CIRCUIT JACK R7
- + B- C+ C- C- B-- FIG. 1 A 1 -3 40 180 110 VOLTS VOLTS VOLTS VOLTS A. C.
neon- Vitte this arrangement, sufficient amplification for good signals is last stalle. When the speaker is plugged into the jack, the obtained by the use of two "high -inn" tubes and a 171 -type in the lamp tube is disconnected automatically from the amplifier.
disc and above the mo- impedance, LI; an output choke of 30 page 427) ; so nothing more need be said directly behind the and as close henries, L2; a filament switch; eleven bind- about it here. tor, with its flat plates parallel ing posts; fixed resistors of the following The scanning disc is merely a flat disc as possible to the back surface of the disc. verti- values: one 100,000-ohm, R1; four 250,000 - of aluminum drilled with a spiral of holes The tube should be placed along the disc, at such a height ohm, 112 and 113. about 3/64 -inch in diameter, as shown in cal center line of the The grid impedance unit LI is used in- Fig. 4. Now please accept a word of kind that the outermost hole of the spiral sweeps edge the plates, and stead of a grid Irak in the last stage, as advice: don't try to make your own scan- ,just under the top of ning disc unless you have available a lathe the innermost hole just above the bottom and a power drill- press, and have had some edge. Any strong, rigid framework that years of experience as a mechanic on pre- satisfies these conditions will serve the cision work. We are showing the details of purpose. the disc as a matter of interest, and not The drawings (Figs. 5 and 6) show an with the expectation of having our readers arrangement of excellent design. A simpb make it themselves. Buy a disc -there are box 31 inches square and 12 inches deep k a number of inexpensive ones now on the made up of 3/4-inch boards, securely fast- market -and you can then expect to see ened together with wood- screws. The cor- good images. ners are strengthened by additional 3 -inch For a motor to turn the disc, you can get strips about l/ inches wide. A shelf to either a condenser -type machine designed 'hold the motor is made of another piece of especially for television work, or a univer- 3 -inch stock about eight inches wide, and sal motor such as are used by the thousands supported by two side and one center sup- for electric fans, vacuum cleaners, coffee ports. No dimensions are given for the grinders, etc. The speed of the motor must latter pieces because they naturally will de- be capable of adjustment by an external pend on the size of the particular motor on rheostat; for it must be slowed down to 450 hand. They should be cut so that the center revolutions per minute for WRNY- W2XAL, of the scanning disc coincides with the cen- The cabinet of the reproducer with the front 900 removed, showing the lamp and the motor with or for the Jenkins ter point of the box. its regulating condenser. The "B" blocks are radio-movies f r o m The neon tube is suspended upside döwn located beneath. conveniently from the top cf the box; its socket can lie The scanning disc, to spaced away trom the board with thin strips shown in Fig. 1. In this position it over- show the image in correct in order to lower the tube to the proper po- the tendency of the amplifier to comes arrangement, must revolve sition with relation to the holes in the disc. "motorboat" when used with a "B" socket - in the direction opposite power device. The tubes Vi and V2 are of to those of the hands of The back of the box may be covered, or a clock. board, the 240 ("high-mu") type, while V3 is a left open. A piece of beaver or 171A. The wiring of the amplifier is simple, and 3XK. A synchronous should give no trouble. The hook -up is that motor, revolving at of a perfectly straightforward resistance - 1,800 r.p.m., can be used only if it is geared coupled system, with an output filter con- to the disc by 1 :1 or 1':2 reduction gears, for sisting of a choke coil (1.2) and a fixed con- WRNY and 3XK, respectively. The 1/4- denser (the last of those marked C). horsepower size of motor is widely available, and is just` right. A special condenser -type BUILDING THE TELEVISOR motor was used in the particular television With the amplifier finished, the next step receiver shown in the accompanying illus- is construction of the scanning mechanism.. trations, and proved exceedingly satisfac- For this you will need the following parts: tory because its speed can be controlled a neon -gas glow -lamp, which fits in a very smoothly by a hand rheostat. 'l'liis standard UX -type socket; a scanning disc motor has a half -inch shaft, on which the 24 inches in diameter, drilled with a spiral Mounting flange of the disc fitted snugly. of 48 round or square holes; a universal or If you happen to pick up a motor with a a condenser-type motor, of not over 1/8_ shaft smaller than IA-inch, you can buy for horsepower; a variable resistor, 0- 10,000 a few cents a bushing to adapt the disc ohms, I15; a rheostat, 100 ohms, Rî; a rheo- to it. a pear -shaped hand stat, 0 -10 ohms, R6, and THE TELEVISOR BOX switch. The lower panel of the cabinet -which was The neon -gas glow -lamp is described in The idea is now to assemble the scanning solidly built -i,, place showing the controls, detail in another article in this number (see apparatus so that the neon tube is mounted (R 5, 6, 7), switch, and lead from tue amplifier.
www.americanradiohistory.com 424 Radio News for November, 1928 similar TA-inch board used for partitions, will be most suitable for the purpose. SINGLE. POLE,
'l'he front of the box should be covered DOUBLE - CONTACT SWITCH NEON TUBE with two pieces of this hoard, one 21 inches FIG. 2 high and the other 10 inches. From the larger piece cut out a hole 1 inches DISC square, directly in front of the square plates LI TELEVISION of the neon tube. On the small board mount MUSIC the three variable resistors R5, 116 and R7, C and two pairs of binding posts, as shown in I.1I111II MOTOR Fig. 6. .1 telephone jack may also be SWITCH mounted on this panel; this device is op- tional and its uses will be discussed later. To facilitate experimentation with the LOUD disc, motor and the neon tube, do not per- SPEAKER R6 manently screw down these front panels at first; but merely turn one or two screws OUTPUT FILTER into each, to hold them in position. C- L2 =30 HENRIES R7 40V C = 0.5 MF. It is well worth while to construct a lox like this, as it will afford absolute protec- AC t ion against the rotating disc. The latter is far less dangerous than any ordinary ' B'' An alternate arrangement for the output of the amplifier shown in Fig. 1. power device but, as a matter of safety. revolving machinery of any kind should be enclosed. If you do not want any- to make the lower panel of the box holding the scan- other in the 110 -volt A.C. circuit. - thing A six as elaborate as this heavy box, use ning apparatus. The inner springs run to foot length of flexible cord is run from the lighter material for the sides, or make up- the connection posts of the neon tube, across pear switch (which is nothing right more than a supports of broomsticks and cover the which are connected also the resistor R5 push button in a small wood case which can sides with cloth. At any event, be sure that and a separate 180-volt "B" battery. Re- be held comfortably in the hand) to the the motor is securely fastened, and that the sistors Iì6 and R7 are in series with each resistor R6. neon tube is not shaken by its vibration. Now turn on your receiver, tune in CONNECTING THE TELEVISOR WRNY or W2XAL with the loud speaker With all the mechanical work done, you plugged into the double- circuit jack, and can now start with the electrical end. As No. 67 adjust the set to give a clear, loud signal. explained by many articles in RADIO NEWS, Turn up the resistor R5 until the neon RADIO NEVs Large blueprints of tube breaks out into a bright pink glow. the neon -gas glow -lamp has the same func- FREE the diagrams in this ar- The glow should take place on the plate tion in a television receiver that the loud BLUE PRINTi ticle, containing infor- facing the disc. speaker has in a music receiver. It trans- ARTICLE mation for the construc- If it appears on the op- posite plate, reverse the lates back into light -impulses the modulated tion of a television ampli- battery connec- tions to it. Further details on the electrical impulses created at the transmit- fier and reproducer as charac- teristics and operation of the glow -lamp ter by the photoelectric cells. (See the first illustrated here, will be sent postpaid article in this issue for a fuller explana- will be found in an article on page 427 of on request. Write to the Blueprint this issue. tion.) It is connected in exactly the same* Department on a sheet of paper sepa- place in the audio circuit that the loud rate from any letter to other depart- Turn on the alternating current to the speaker ordinarily occupies. ments; print your name and address motor, and adjust 117 so that the latter The best arrangement is shown in Fig. ]. legibly and ask for No. 67. (See also turns at about half its normal speed. Turn The two output posts of the resistance - page 449.) This will avoid possible off all the lights in the room. The instant coupled amplifier are led to a double- circuit delay. the buzz -saw note of the television signals telephone jack, which may be mounted on comes through the loud speaker, pull out
0.5 MF CONDENSERS F. E C
o v C o 0 C 0 C _ SOCKET -lc SOCKET OUTPUT F.l R3 Ni j R2 V2 R2 V3 CHOKE F... 1 ¡ r 0 0 1 .0 0 R1 oo oo L1 0o o) oO \oO oO OUTPUT O °0 E-'' .,. " POSTS RESISTOR MOUNTINGS R33 SOCKET O t GRID C'; v O 1 IMPEDANCE TO DETECTOR O R4 R4 C1 ÍIJR4- FILAMENT SWITCH BALLASTS BATTERY BINDING POSTS
OO O O O O O WOOD BASEBOARD FIG. 3
A simple layout for an amplifier such as that shown in Fig. 1. It choke. The output may be connected as in Fig. 2, above, for uses straight resistance coupling in the first two stages (see pre- .greater convenience. It is possible, also, to have the tube and ceding pages for values), a grid impedance coil, and an output speaker in series, with a slight additional "B-} -" voltage.
www.americanradiohistory.com Radio. News for November, 1928 425
plug and start playing with JE -r- .0I -, a the speaker ,- í o the motor rheostat, R7. r wor v OPERATING IS SIMPLE 0 If you have no tachometer (speed in- C do is to run the 1' dicator), the only thing to motor up and clown the scale. When you hit 450 r.p.m., the crazy criss -cross lines that are shooting back and forth and up , '. e ei1 Q and down the surface of the disc in front -3 of the neon tube should melt into a rough image of a man's face, or other distinguish- 2 able object. You will notice that, with no ^.+ X Y- Cl signal being fed to the neon tube, the square O p you observe through the .01 - of pinkish light C disc is streaked with fine dark lines. The h ^ J instant the audio signal is turned on, this J even glow will be modulated by the fluctuat- J U O Q M J ing currents. When you hit 450 r.p.m. and > _ m the image of the man's face literally un- curls itself from the hodge-podge you saw s ó F before, you will experience a thrill that will t make all the effort well worth while. You 9 °,F ó probably received a big "kick" from your m"g first successful broadcast receiver but, ^ when you see your first television image, y oO a S Et h you will know what a real thrill is. ^ o In the absence of any synchronizing sys- é` tem, the images will tend to wander out of view but, by carefully manipulating the con- ° ^ t o trol rheostat R7, you can find the proper - e e i3m setting for 450 r.p.m. The use of the smaller rheostat R6, with its switch, is more or less incidental. Set R6 to about half its value, and just press the switch for an in stant when the images start to run off. This 0 c y O p will cause the motor to jerk and speed up m z o for a second. ó o If you are using a universal motor, you 3 mi can disregard 116 and its switch altogether and depend on 13.7 for the speed control. m 5 ció The images you receive may be upside ó á ó down, or the WRNT televised card may z W read backward. To correct these condi- m tions, follow the operating hints given in z o N ,E ó the article on pages 428 -9. ÿ m ó OTHER ARRANGEMENTS m ?J m An alternate circuit arrangement is ó E is con- .1E- O U Ó shown in Fig. 2. Here the neon tube cyw nected directly in series with the plate cir- g m cuit of the last audio tube, with a single - Q m U m m pole, double- contact switch to shift the out-
O put of the tube. The rest of the amplifier F- W Ó and motor circuit is exactly like that of 0Ñ Á. aa o ÿ Fig. 1. This is a simple hook -up; but its 0 o main disadvantage is that the voltage ap- N Ó m ÿ W m plied to the "13-1-" post must be at least G U ó o 300 volts, as there is a drop of about 150 m volts across neon itself, and V3 .O the tube m is a 171A, which operates on 180 volts. As n no "B" power unit designed for 171 opera- 3 tion will supply more than about 220 or _W 250 volts, it will be necessary to connect ; z a'. á .. one or two 45 -volt "B" battery blocks in " ÿ ó series with the highest voltage lead from the m F unit you have. At least, this will be cheaper Z g m than using four 45-volt blocks for the hook- a up of Fig. 1. Cr Several experimenters have used a "B" W m ti power unit for the neon -tube illumination O p O with good success, but separate batteries
a_^, are really the cheapest, easiest and most satisfactory source of supply. m v The audio amplifier need not be limited to a 171A for the output stage. A 210 -type E. VI S power amplifier will work perfectly well, w IAAz e " but in this case the shunt -feed scheme of á m ó Fig. 1 should be used. The series arrange- w g ment of Fig. 2 will strain the power pack C U , and the neon tube is likely to be burned up .44>. A. 'PG by the high plate current. With the Fig. 2 mg m -,J F ;1 (Continued on page 466)
www.americanradiohistory.com 426 Radio News for November, 1928 Synchronized Broadcast Joins Images and Music Wire Transmission of Image- Frequencies and Radio Reception of Sound Enable Audience to See as Well as Hear Miniature Drama
JitETASTE of the radio television eventually be combined with the simultane- quencies which makes up the television band of the future, accompanied as it ous transmission of speech and music; but 'l'he arrangement of the apparatus appears will be by radio "teleaudition," was this is impracticable at the present moment, in the illustration; the scanning disc man A given to radio fans in Newark, N. J., from the viewpoint of both transmission and be seen directly in front of the demonstrat- during the week of August 19, when a reception: However, by the use of a wire ing engineer, and the source of illumination demonstration of "wired television" syn- line, we are able to present the effect of is housed in the hood behind the disc. 'l'he chronized with musical radio reception was synchronized reception of a radio program frame before the disc contains the four presented at the huge department store of consisting of simultaneous music and tele- photoelectric cells and the first five stages L. Bamberger & Co., owners of station vision." of the amplifier. The final stage of 210 - WOR. On its sixth floor the transmitter THE SYSTEM EMPLOYED type tubes, in push -pull, is contained in the and receiver, linked together by short wire small box on the table at the right, and the lines, had been installed 1w their manufac- The "wired -television" apparatus em- "B" power -supply unit is in the larger box turer, the Daven Radio Corporation of the ployed is similar in principle, of course, to beside it. same city; and two -hour marionette per- other installations recently demonstrated formances were daily enacted before the over radio channels, both short and long - RECEPTION ADJUSTMENTS transmitter and reproduced before the eyes wave. The transmitter comprises a 48 -hole the range of frequencies required of the radio spectators in synchronism with scanning disc, 24 inches in diameter and Since by the television dramas ran far beyond broadcast the saune time from rotated at 1,000 revolutions per minute by the music at broadcast channels, the transmit- WOR. The little dance of the puppets was its motor, and four 7-inch photoelectric available ter was connected directly .by wire to the repeated each two minutes during the period cells. A 900 -watt tungsten lamp produces receiver on the same floor. The latter ap- of the demonstration; as the limitations of the light bean which the scanning disc paratus also is standard; it is housed in a lamp and screen used in the receiver, as causes to "explore" the field of its subjects the wooden cabinet, approximately 30 inches in other present- moment television ap- a trifle over sixteen times a second. A con- and wide, and 8 inches deep. The as- paratus, prevent the image from being seen densing lens aids in this task of illuminating high sembly comprises the conventional scanning many once. the miniature stage. 'l'he light reflected, by at disc with its motor, and the neon-filled glow - said a representative spot by spot, from the surfaces covered by "It is our belief," The controls on the front of the explaining the reason for holding the dancing beam emitted by the lamp is tube. of WOR, housing include a resistor governing the the demonstration at this time-that of giv- converted into electrical pulses by the photo- speed of the motor, a switch turning it on ing the public a basis on which to found an electric cells; and these signals are passed off, a rheostat regulating the direct -current importimce of television through a six -stage resistance -coupled am- or idea of the coming voltage across the plates of the neon tube, in radio programs of the comparatively near plifier of special design to handle the com- future -"that television broadcasts will bination of audible and supersonic fre- (Continued on page 476)
Set up of the television transmitter used at IVOR during the synchronized transmission. The puppets' "stage" is nt the extreme left; the apparatus is of the usual type.
www.americanradiohistory.com Radio News for November, 1928 427 The Neon Tube Television's "Loud Speaker" How This Marvelous Device Makes Possible the Distant Reproduc- tion of Moving Scenes Simultaneously with Their Occurrence By D. E. Replogle
NE of the essential components of one to the other. An excellent insulator is separation at just the right value, while the a television receiver is the glow - now presented by the intervening gas. Why? supporting rods between the stem and the lamp; this and its associated scan- The explanation is steeped in academic lower edges of the plates serve the same 0 ning device serve the sane purpose science, which is usually far beyond the purpose at the bottom. The cross rod at in the television apparatus that the loud realm of the layman. Furthermore, no one the top of the plates is merely to prevent speaker serves in the radio set. has ever seen atoms or electrons; hence cold the plates from being bent away from their This remarkable device, as most success - logic steps in to explain things which man normal vertical plane, as a result of jars fully developed, utilizes neon gas as the may never see for himself. However, if during transportation. This brace serves luminous element, and is the only lamp yet we may be permitted to make a free trans- also to prevent vibration of.the plates when known which, without prohibitive cost, can lation into lay language, of a theory by the tube is mounted on the sanie framework be made, satisfactorily, to meet the require- C. G. Smith, inventor of the "S" tube, the as the scanning -disc motor, as frequently is ments of the present television systems; in story runs about like this: the case. which there is required a light -source, of The facing charges of electricity are The bull) surrounding the two plates is uniform intensity over a large area, which bound to produce action. Some loose elec- of particularly clear glass, to permit the will instantaneously vary in brilliancy with tron in the gap between the charged con- radiation of the maximum amount of light. variations in the television signals. The ductors is coaxed toward one or the other, 'fhe tube contains neon gas, at a low pres- television lamp most strikingly differs from and rapidly accelerates its rate of travel sure, together with certain alkaline sub- the familiar electric lamp, in that it gives until its speed is sufficient to smash those stances which increase the speed of opera- off a soft orange "glow" from a large sur- atoms obstructing its path. The collisions tion imd the intensity of illumination. face which may be looked at without hurting result in ionization, or the breaking down The tube is fitted with a standard UX the eyes, rather than the dazzling white of the gas, which then becomes a fair con- base. The luminous plates are placed in a "spot" of an incandescent tungsten filament. ductor of electricity; or, to put it another plane at right angles to the axis of the The color of this glow may be readily con- way, there is now a wholesale movement socket pin. In a television receiver, there- trolled in manufacture by variation in the of electrons. It is evident, then, that the fore, the pin should point directly either to kind and quantity of gas employed within electron needs a good running start, so to or away from the scanning disc, in order the bulb. speak, in order to smash things up in that the glow -lamp's plates may be parallel As will be seen from Fig. 1, the con- general. Failing in a good running start, to the disc. Connections are made to the struction of the television lamp is apparently the electron does no smashing, ionization plate, and one of the filament, prongs of the quite simple; although this simplified ap- cannot take place, and there is no electrical socket. pearance has been secured only after a conduction; the gas, under such circum- great deal of research work with gaseous - stances is a good insulator. Some gases CIRCUIT CHARACTERISTICS conduction tubes and neon lamps of all require a longer path for ionization than types and for many different uses. Indeed, others, which is another important con- As with all types of gas -discharge tubes, the development and refinement of this sideration. Helium is especially ideal in the neon lamp has a very pronounced "nega- device has involved a review of many rare this respect, having an exceptionally long tive- resistance" characteristic and a stabiliz- gases, a deep study of atomic structure, free path. ing resistor must always be used in series and a long process of reasoning out the with the lamp and the supply voltages. acrobatics of electrons. The highly intricate CONSTRUCTION OF THE GLOW LAMP (This is just a technical way of saying that action taking place in the miniature universe The "short- path" principle, then, is the internal electrical resistance of the lamp of the gas contained in the television lamp adopted merely to prevent electrons from decreases as the current through the lamp is, therefore, not at all in keeping with getting a gtiod running start; it is prac- is increased. Thus, if no current -limiting the utter simplicity of the mechanism and tically applied in insulating the inner sur- resistor were to be used in series with the electrical features of the device; yet we faces of the two electrode plates most ef- we must master the first before can enjoy fectively. - the second. Glass spacers are arranged at the top - ITS ACTION A PARADOX edge of the plates in order to maintain this The "glow" takes place uniformly over the surface of either one or the other of the two flat and parallel plates (P and PI, Fig. 1) ; the effect depending upon which plate is connected to the positive and which to the negative side of the power supply. The two parallel plates are so placed with respect to each other as toT utilize the prin- ciple of "short- path'-insulation in order to prevent "glow" between the plates which, of course, would not be very desirable. The "short- path" prinçiple is one of those scientific truths that are stranger than fiction. Briefly, in a gaseous conducting nteditms, if we have oppositely -charged metallic bodies of sufficiently high potential difference, the gas between will "break down" or "ionize," and conduction will take place from one to the other. However, move these same conductors very close to each other, and the gas between is no longer ionized; Which is apparent from the fact that there is no longer a glow present in the tube. Current ceases to flow from The steps in the assembly of a glow lamp: A, glass stem and wire supports, ready for the plates. B, plates mounted in position. C, plates completely assembled, with top wire supports. " Raytheon Manufacturing Company D, tube ready for evacuation. E, completed tube ready to work.
www.americanradiohistory.com 428 Radio News for November, 1928
tube, the current would tend continually to While the impedance of the neon lamp is increase and, as it increased, the resistance quite low -500 ohms -it should. be operated Fig. 1 of the tube would automatically decrease, directly in the output circuit of the power causing still further current increase and so tube (either UX -171 or UX -210) without on; until an excessive current value was using any impedance -adjusting device. Such reached and the lamp destroyed.) A re- an arrangement is used because the tele- sistor which is smoothly variable through a vision lamp is a current -operated device wide range (0- 500,000 ohms) will be found rather than a power -operated device; there- very convenient for this purpose; as not fore the most desirable output circuit ar- P1 P only does it stabilize the tube operation, hut rangement is one which provides for a maxi- it serves also as a ready means for adjust- mum of current change in the plate circuit GLOW-LAM? ing the current through the lamp, and thus of the power tube in which the lamp is SYMBOL its brilliancy, to the desired value. connected. As will be seen from Figs. 2 and 3 a D.C. voltage of 180 is required for proper opera- REVERSING THE COLOR EFFECT PIN tion. By means of the series variable re- It has already been mentioned that lamp may changing the D.C. connections to the tube FRONT REAR sistor, the current through the PLATE PLATE then be controlled between 5 and 20 mil- changes the "glow" froid one plate to the P P1 liamperes. With a current of less than 5 other. Interchanging the A.C. connections, milliamperes, the glow on the plates is not on the other hand, reverses the character of uniform and, therefore, not satisfactory for the image, in the reception of television. television use. As the current is increased Thus one connection will give a positive in intensity from 5 to 20 milliamperes, the picture, and the reverse a negative. That glow remains very uniform and increases in such a condition is possible will readily be END VIEW OF BASE in excess of 20 mil- seen if we consider the instant at which intensity. Currents SHOWING CONNECTIONS liamperes should not be passed through the one A.C. lead is positive and the other nega- tube or its life will be materially shortened. tive. If these leads are so connected to the As will be seen, either a separate D.C. electrode plates that the A.C. " lead and The details here show more clearly the arrange- +" ment of the neon tube's elements. The ar- source (which may be either batteries as the D.C. " +" lead are on one plate, and the ticle explains why the glow is on the outside in Fig. 3, or a good "B" power unit), of else, A.C. " -" and the D.C. " -" lead on the of the plates -not between them, as might be in some instances, the plate current of the other, the "instantaneous" current through expected. power tube itself, as in Fig. 2; may be used the tube is equal to the instantaneous A.C. to light the lamp. In case the regular value plus the steady D.C. value and the will power -tube plate supply is used, the plate- instantaneous brilliancy of the illumination illumination be below, rather than to- filament resistance of the power tube is greater than normal. above, normal. See Fig. 4 on the next page. serves as the stabilizing resistor and the If, on the other hand, however, the A.C. Thus, in the first instance, a signal im- plate voltage must be increased from the leads have been interchanged with respect pulse results in the illumination of the tube normal value (180 volts in case of the to the D.C. leads, the instantaneous value getting dimmer, and in the other brighter; which in in a positive UX -171 type) by an amount equal to the of the alternating current opposes the direct turn, results picture in a in drop across the lamp (about 150 volts). current and, as a result, the brilliancy of the first instance, and negative the second, providing the polarity of the signal voltage is the saine as it was at the trans- 71 TUBE GLOW-LAMP mitting end. In the case of some amplifiers, A higher "B -I-Max however, the instantaneous polarity of the voltage is needed in Fig. signal voltage may be reversed by the time 2, where the power tube's it reaches the television lamp; this is the plate current lights the VARIABLE neon tube; while in Fig. case with a "grid leak- condenser" detector RESISTOR 3 the additional batteries working into an even number of resistance - are across the latter only coupled audio stages. In such an instance, (Sec page 423). The image would value of the coupling con- a reversed or negative always 11111111 denser is not critical. . be obtained if it were not possible to correct 300 VOLTS' 64- 18o V. matters simply by reversing the lamp con- Fig. 2 3 Fig. nections.
How to Adjust the Television Receiver for Operation
THE first step in the reception of a 18 to 20 cycles (per second), the television of these faults can be corrected quite easily. television image is the locating of the signal contains high- frequency- notes whose It is quite obvious when an image is up- signal on the receiver dials. This character depends upon the nature and side down, and the correction of this fault is best done with the aid of head- the position of the subject before the trans- is equally obvious. The subjects before the phones or a loud speaker connected in place mitter pick -up. transmitters at most stations broadcasting of the neon tube. Do not fail, however, to The experimenter will hear a signal television are scanned from top to bottom have a fixed condenser of about 1 mf. ca- which sounds at first like a flutter and will during one rotation of the disc. Accord- pacity- in series with the phones when con- then note that this flutter is really the rapid ingly, if the receiving disc is so rotated nected in place of the neon tube or across repetition of a high-frequency note. The that the plate of the neon tube is scanned -its terminals. nature of this note and its loudness con- from the bottom to top, the picture will be The television signal has a distinctive stantly change as the subject before the inverted. 'ro reverse the manner in which sound but, unfortunately, the short -wave transmitter moves or is changed. For in- the neon lamp plate is scanned vertically, it band contains several signals that. may stance, a newspaper rolled up and held in is necessary either to reverse the rotation of easily be mistaken for television. For in- a vertical position produces a distinct note the disc or to remove the disc from the stance, the high -speed code transmissions which is very clean cut. A hand does not driving motor and turn it around. The of such stations as WIZ and WQO are produce so clear a note, yet the signal is latter operation may involve the removal of quite like a television signal because of the of the same general nature. the hub and remounting on the opposite "flutter," or what may be called a "group side of the disc. frequency." On the broadcast band, in . "CRAZY" IMAGES Whether or not the received image is re- which WRNY operates, this trouble will The television experimenter may, upon versed horizontally, is impossible to tell not be experienced. his first attempts, be puzzled to find his unless one happpens to know the scene be- In addition to a low "group frequency," received images either turned upside down, ing transmitted, or unless distinctive char- which is the rate at which complete pic- or else reversed as when looking through a acters are held before the transmitter pick- tures are transmitted and which is around photographic negative the wrong way. Both up. For example, one of the objects often
www.americanradiohistory.com Radio, News for November, 1928 429 placed before the transmitter pick -up at In the experimental work at WLEX it transmission hopeless -and still a fair im- station WLEX, in Boston, is a micro- has been found that the television signal age can be received. Of course, noise does phone stand with the station letters mounted may be almost submerged in noise and yet not help matters; it produces a mottled on it. If the image of the microphone stand provide an image. This fact will undoubtedly background and tends to speckle the pic- and letters is received with the object erect be of interest to those who are already try- ture itself. Extreme noise will produce but reversed (so that the letters read ing to receive the signals from WGY and dark lines of varying width across the field "XELW ") then the scanning disc is being WRNY and who think that reception is of the image. But in spite of this, the so rotated that the holes pass the glowing picture is there and, since noise is non - plate of the neon tube in the wrong di- periodic unless introduced by vibration front rection. the motor and disc, the speckle and dark The correction of this fault is not so lines are continually shifting their positions obvious. It is plain that whether the ex- while the image remains generally stationary perimenter scans the plate from top to bot- or moves in an orderly fashion. tom or from bottom to top, makes the dif- Therefore, if in the experimenter's at- ference between the picture being right- tempts to receive television images, he finds side up or upside down. Similarly, whether the signal more or less accompanied by the experimenter scans the plate from left noise, he should not judge the noise by to right or from right to left makes the speech broadcast standards, but go right difference between seeing the image cor- ahead and try the signal on the disc. It rectly or reversed. goes without saying that the minimum of How can we make the holes pass the plate noise should be introduced by the set it- in the opposite direction and still progress self. Loose connections in the microphonic from top to bottom? Reversing the rota- tubes, noisy resistors, and other causes of tion of the disc alone will turn the image noises should be avoided. upside down. The disc must also be turned When a good television signal is being around on the shaft of the motor. Thus received, it sounds quite like a slowly -re- if the image is right -side up but reversed, volving circular saw which is slightly off we must reverse the direction of rotation Fig. 4 center. In other words, one hears a high - which might correspond to the of the disc, and also remove the disc from lrhen the image is negative, as shown at the pitched note the shaft and turn it around with the other right, the .4.C. signal is working against the tooth frequency, and broken up into groups side out. battery. Reversing the leads to the lamp is whose frequency corresponds to the rate In spite of the fact that these two factors the simplest remedy. at which the saw (the disk) rotates. The make three wrong combinations and only latter we have referred to as the group one correct one, the wrong combinations hopeless, because of the noise caused by frequency while the high -pitched note is provide perfectly recognizable images whose daytime electrical disturbances and the the modulation introduced by the scanning worse fault is to be upside down. static of warm weather. spot. If the dlise speed is high and the sig- Should the image obtained be a negative It is true that, when we are interested in nal is weak, it may easily happen that the instead of a positive, the trouble is due listening to a signal, the noise level is an only sound audible in a pair of phones will to reversed A.C. connections to the neon important determining factor; but in the be the group frequency. Even so, this is tube. Interchanging these connections will case of television, the noise level may be no indication .that a fair image cannot be correct the trouble. high -in fact, so high as to make speech received.
Television Teems with Trials for Telexperimenters
Editor, ltADto NEWS: graphs and the like seem to call for such far as the working details are concerned, In the interest of the science please allow activity on the part of an enterprising ex- very much in the stage of experiment. The me to make this suggestion: get the broad- perimenter as our imaginative artist has (Continued on page 475) cast stations and the experimenters in tele- portrayed. vision together and confine their experi- However, the thing to be remembered is ments to the same type of scanning discs that all these transmissions are still, so and same speed. You can well see the trouble that is sure to arise, with every different station using a different number of holes and .with different-speed motors. As yet I have not tried to receive any pictures from these stations on account of atmospheric conditions and the distance from the televisor; having confined my ex- periments to a simplified method of syn- o chronism. I can get a stable speed on one 0 frequency but, when shifting from one speed to another, great difficulty is experi- o enced; and of course the layman will have even more trouble when he attempts this adjustment. Then too, how many television receivers do you suppose can be sold when the user is told how many discs will have to be changed before tuning from one sta- lion to another? Please accept this criticism or rather this suggestion in the same spirit it is given. WII.VER N. BARNES, 1120 No. 22 Street, Waco, Tex.
A DAY-AND-NIGHT TASK From one standpoint, our correspondent's good -natured protest may seem well justi- fied; the numerous systems now projecting The paradise -or will it be purgatory ? -of the radio experimenter who tries to radio television, radio movies, radio photo- keep up with everything new in radio imagery. (Drawn front imagination.)
www.americanradiohistory.com 430 Radio News for November, 1928 List of Broadcast Stations in the United States
n Radio Radio 211 Radio Radio .1 eII Call BROADCAST STA. éi Call BROADCAST STA. at ; q Call BROADCAST STA. eö óñ Call BROADCAST STA, q XII Letters Location 3g fr.X Letters Location $3 Letters Location t! a.3 Letters Location E C3
KD KA last Pittsburgh. Pa.. 316 50000 KGO Oakland, Calif "384 5000 WBAK Harrisburg, Pa. (day). 300 500 WGN -WLIB Chicago Ac Elgin, I1141615.000 KO LR Devils Lake. N. D 231 15 KGRC San Antonio, Texas... 220 WBAL ?Baltimore. Md "286 5000 W GR Buffalo, N. Y 303 750 K O YL Salt Lake City. Utah 234 500 KGRS Amarillo, Texas 244 250 W B A O Decatur, Ill 268 103 W CST Atlanta, Ga 270 500 N EJK Los Angeles. Cal 252 250 KGTT San Francisco, Calif 220 50 WBAP Fort Worth, Texas 500 5000 W HA Madison, Wise 333 750 KELW Burbank. Calif 229 500 KGU Honolulu, Hawaii 270 500 W BA W Nashville. Tenn 240 5000 W HAD Milwaukee, Wise 270 500 KEX Portland, Ore 278 2500 KGW Portland. Oregon 492 1000 WBAX Wilkes Barre, Pa 250 100 WHAM Rochester, N. Y '280 5000 KFAB Lincoln, Neb 319 5000 KG Y Lacey, Wash 246 WBBC Brooklyn. N. Y 227 500 WHAP ?Carlstadt, N. J 236 1000 KFAD Phoenix, Aria 322 500 KHJ Los Angeles, Calif 400 10ÓÓ WBBL Richmond, Va 234 100 W HAS Louisville, Ky 322 500 KFAU Boise, Idaho 286 2000 KHMC Harlingen, Tex 236 100 WBBM ?Glenview. Ill "389 5000 W HAZ Troy, N. Y. (Monday) 306 500 KFBB Havre, Mont 275 50 KHQ Spokane, Wash 370 1000 WBBR Rossvile, N. Y....., 256 1000 W H B Kansas City. Mo 341 500 K F B K Sacramento. Calif 275 100 KICK Red Oak, Iowa (day) 322 100 WBBW Norfolk, Va 236 100 W H BC Canton, Ohio 236 10 KFBL Everett. Wash 224 50 KJBS San Francisco. Calif 245 100 W B B Y Charleston, So. Car 250 75 W HB D Bellefontaine, O 222 100 KFBU Laramie, Wyo 484 500 RJR Seattle, Wash 349 2500 W BC N Chicago, Ili 288 500 WHBF Rock Island, Ill 222 100 KFCB Phoenix. Aria 244 125 KKP Seattle, Wash 203 15 WBES Salisbury, Md 265 100 WHBL Sheboygan. Wis 204 250 KFCR Santo Barbara. Calif 211 100 KLON Blytheville, {irk. (day) 286 WHET Medford, Mass 288 500 WHBP Johnstown, Pa 229 250 KFDM Beaumont, Texas 484 500 KLOS Independence, Mo , 270 15ÓÓ WBIS See WNAC W HS Q Memphis, Tenn 232 100 KFDX Shreveport. La 236 250 KLRA Little Rock, Ark.... 204 50 WBMH Detroit, Mich 211 100 WHBU Anderson, Ind 220 15 KFDY Brookings. S. D 545 500 KLS Oakland, Calif 246 250 WBMS Union City. N. J 200 100 W HB W Philadelphia. Pa 220 100 KFEC Portland. Ore 214 50 KLX Oakland. Calif 508 500 W B N Y New York, N. Y 236 500 W HB Y West De Pere, Wks 250 50 KFEL Denver. Colo 227 250 KLZ ?Dupont. Colo 353 1000 W BO Q Richmond Hill. N. Y 309 500 WHDI Minneapolis, Minn 246 500 KFEQ St. Joseph. Mo 231 1000 KMA Shenandoah, Iowa 395 1000 WBO W Terre Haute, Ind 208 100 -WA BO WBRC WHEC Rochester, N.Y. 254 '250 KFEY Kellogg, Idaho 232 10 KMBC see KLDS Birmingham, Ala 303 250 WHFC Chicago, Ill 216 100 KFGQ Boone, Iowa 210 10 KMED Medford. Oregon 270 50 WBRE Wilkes Barre, Pa 250 100 WHK Cleveland, Ohio KM IC 224 WBRL "265 500 KFH Wichita, Kan 246 500 Inglewood. Calif 25Ó Tilton, N. H 232 500 W H N New York, N. Y 395 500 KF HA Gunnison. Colo. 250 50 KMJ Fresno. Calif 366 WBSO Wellesley Hills. Mass. 384 100 WHO Des Moines. Iowa KM WI Clay Center, Neb 286 WBT 535 5000 KFI Los Angeles, Calif 468 5000 250 Charlotte, No. Car 258 1000 W HPP Englewood. N. J 205 10 KF IF Portland. Ore 229 50 KMO Tacoma. Wash . 254 500 WBZ ?Springfield, Mass. -.333 15,000 W HT ?Chicago. Ill 306 5000 Wash 246 100 KMOX Louis, Mo 300 5000 WBZA Boston, Maas KFIO Spokane, tSt. 333 500 W IA Philadelphia. Pa 288 100 KFIU Juneau. Alaska 225 10 KMTR Los Angeles. Calif 516 500 WCAC Mansfield, Conn 535 500 W IAS Ottumwa. Iowa (day) 100 KNRC Santa Monica, Calif 375 500 WC AD Canton, 322 100 KFIZ Fond du Lac. Wis "268 N. Y 244 500 WIBA Madison, Wle 240 100 KFJB Marshalltown. Iowa 248 100 KNX Los Angeles. Calif 337 500 WC AE Pittsburgh, Pa 461 500 WIBG Elkins Pk..Pa.(Sund'ys)441 , 273 KOA Denver, Colo 326 5000 W CA 50 KFJF Oklahoma City. Okla 5000 Columbus, Ohio 234 250 W 180 ?Chicago, 111 250 KOAC Corvallis Oregon (day) 270 7000 WCAJ Lincoln, 306 5000 KFJ I Astoria. Ore 50 Neb. (day) 380 500 W IBR Steubenville, Ohio 250 50 KFJM Grand Forks. N. D 333 100 KOB State CollegeN ew Mex :395 502(100 WCAL Northfield, Minn 286 500 Elizabeth, KOCH Omaha. Neb 258 WC AM Camden. W IBS N. J 204 250 KF JR Portland. Ore 240 500 N. J 224 500 WIBU Poynette, WO 217 20 Y Dodge. Iowa 232 100 KOCW Chickasha. Okla 252 250 WCAO Baltimore, Md 244 250 KFJ Fort W I B W Topeka. Kan. 204 250 KFJZ Fort Worth. Texas 250 50 KO IL Council Bluffe. Iowa 319 5000 WCAP Asbury Park, N.J 240 '500 N. Colo 250 KO IN ?Portland. Oregon. 319 1000 WCAT Rapid WIBX Utica, Y...... 238 150 KF KA Greeley. 500 City. So. Dak 248 100 W IBZ Montgomery. Ala 231 KF KB MUford. Kansas 242 1500 KOMO Seattle. Wash 309 1000 WCAU Byberry, Pa 261 1000 15 KORE Eugene, Ore. "00 WC A W ICC Easton, Conn 265 500 KF KU Lawrence. Kansas 254 505 X Burlington, Vermont 254 100 W IL St. Louis. Mo KF KZ Kirksville, allmoUrl 225 15 KO W Denver. Colo 219 250 WCAZ Carthage, Ill 250 5o 258 250 W INR Bay Shore, N. Y 211 500 KFLV Rockford, Il. 268 100 W IOD Miami Beach, KFLX Galveston. Tuns 270 100 Fia 248 1000 W IP Philadelphia Pa 349 500 W 461 20ÓÓ ISN Milwaukee, Wie 270 250 KF NF Shenandoah,lowa(day) W IVA Norfolk, Va KFOA Seattle. Wash 447 1000 list be superseded on 210 100 KFON Long Beach. Calif 242 1000 will November 11, 1928, by a new WJAD Waco, Texas 333 500 KFOR Lincoln. Neb 217 100 THISallocation. The new apportionment, as officially confirmed, will WJ AG Norfolk, Neb 286 250 for WJAK Kokomo, Ind 234 50 KFPL Dublin. Texas 275 15 appear in RADIO NEWS December, and should be consulted WJAM KFPM Greenville. Texas 231 15 by readers at that time for new wavelengths, etc. Cedar Raplds.Iowa 240 250 Ark 263 WJAR Providence, R. I. 484 500 KFPW Sulphur Springs, 50 WJAS Pittsburgh, KFPY Spokane. Kash 248 250 1 Pa... 270 500 KFQB Fort Worth, Texas 333 1000 WJAX Jacksonville. Fla. 341 1000 KFQD Anchorage. Alaska 345 100 W J A Y Cleveland. Ohio 227 500 WJAZ ?Mt. Prospect, Ili 263 5000 KFQU 1101y City, Calif 220 100 231 100 KPCB Seattle, Wash 100 WC BA Allentown, Pa 222 100 WJBB Sarasota, Fia 238 250 KFQW Seattle. Wash 217 KPJM 214 15 Calif 232 250 Prescott. Aria WC B D Zion. III 345 5000 WJBC LaSalle, Ill. 227 100 KFQZ lioli wood. KPLA Los Angeles. Calif 288 500 WCBM WJBI Red Calif , 454 1000 Baltimore, Md 225 100 Bank, N. J. 263 100 KFRC San Francisco. KPO San Francisco. Calif 422 1000 WCBS Springfield, WJBK Ypsilanti, Mich Columbia. Missouri 250 . 500 IB 210 250 220 15 KFRU KPOF ' Denver, Colo 201 500 KFSD San Diego, Calif 441 500 WCCO ?Minneapolis, Minn-m.405 5000 WJBL Decatur, Ill 213 250 KPPC Pasadena. Calif 316 50 WCDA Cliffside, N..1 213 250 WJ BO New Orleans, La 263 100 KFSG Los Angeles. Calif 252 500 KPQ Seattle. Rash 231 100 KFUL Galveston. Texas 258 500 WC F L Chicago, Ill 484 1500 WJBT Chicago, III. 389 500 KPRC Houston, Texas 294 1000 WCGU Brooklyn, N. Y 219 500 W J B U Lewisburg, Pa. 214 100 KFU M Colorado Spgs., Colo , 488 1000 KPSN Pasadena. Calif 316 1000 KFUO ?Clayton. Mo 545 1000 WC LB Long Island City, N.Y 200 100 WJBW New Orleans, La 238 30 KQV . Pittsburgh. Pa. 270 500 Colo 227 100 WC LO Kenosha, Wise 227 100 WJB Y Gadsden, Ala 234 50 KFUP Denver, K Q W San Jose. Calif . 297 500 WJJD KFUR Ogden, Utah 225 50 WCLS Joliet, Ill 216 100 Mooseheart, Ill "366 1000 KRE Berkeley. Calif. 231 100 WC MA Culver, Ind 261 500 WJ KS Gary, Ind 232 500 KFVD Culver City. Calif 216 250 KRLD Dallas. Texas 461 500 KFVG Independence. Kan 225 50 WC OA Pensacola, Fla 250 500 WJR -WCX ?Pontiac, Mich 441 5000 KRMD Shreveport, La 220 50 WC OC Columbus, Mies 231 500 WJZ ?New York, N. Y "45430.0í0 KFVS Cape Girardeau, Mo 224 50 KRSC Seattle. Wash 273 50 KFWB Los Angeles, Calif 353 1000 WCOH Greenville, N. Y 211 250 WKAQ San Juan, Porto Rico 322 500 KSAC Manhattan. Kansas 333 500 W C R W Chicago, Ill 224 100 WKAR East Lansing, Mich 278 500 KF WC Ontario. Calif 248 100 KSBA La 268 1000 KFWF St. Louts. Mo 214 100 ?Shreveport, WCSH Portland. Maine 366 5000 W KAV Laconia, N. H 224 50 KSCJ Sioux City, Iowa 244 '500 W CSO Springfield, Ohio. W KBB Joliet, Ill 216 100 KF W I Sao Francisco, Cal 268 500 256 504. KSO St. Louis. Mo 545 .500 W C W K Fort Wayne, Ind 214 100 W KBE Webster, Mass 229 100 KFWM Oakland, Calif 236 500 KSEI Pocatello. Idaho 333 250 KFWO Avalon. Calif 300 250 WCX See WJR WKBF Indianapolis, Ind 252 250 KSL Salt Take City. Utah 303 5000 WDAE Tampa Fla 268 WKBH La Crosse, Wis 231 590 KFXD Jerome, Idaho 204 15 KS 273 100 500 MR Santo Maria. Calif WDAF Kansas City, Mo 370 W KB 1 Chicago, Ill 216 50 KFXF Denver. Colo 283 250 Iowa 227 500 1000 50 KSO Clarinda. W DAG Amarillo, Texas 263 1000 W K B N Youngstown, Ohio 214 50 KFXI tEdgewater,Colo.(near)210 9(500 Sioux Falls, So. Dak 210 250 WDAH El Paso, Texas WKBO Jersey City, N. J 219 KFXR Oklahoma City. Okla 224 50 KSTP Westeott, Minn 220 3500 234 100 250 KFXY Flagstaff. Aria. 205 25 W DA Y Fargo, No. Dakota 545 250 WKBP Battle Creek. Mich 213 50 KTAB Oakland. Calif 230 500 W D BJ Roanoke. Va... WKBQ New York, N. Y 219 250 KFYO Breckenridge, Tex 211 100 KTAP San Antonio, Texas 229 250 231 250 KFYR Bismarck, No. Dak 250 250 WDBO Orlando, Fla 288 '500 WKBS Galesburg. Ill 217 100 KTBI Los Angeles. Calif 275 1000 WDEL Wilmington, Del 297 WKBT New Orleans, La 252 50 KGA Spokane, Wash 261 2000 KTBR Portland. Oregon 229 500 250 WKBV KGB San Diego. Calif 248 100 WDGY Minneapolis, Minn 286 500 Brookville, Ind 219 100 KTHS Hot Springs, Ark 500 '1000 W DO D W KB W Amherst, N. Y 217 KGAR Tueson, Aria 234 100 KT NT Muscatine. Iowa 256 2000 Chattanooga, Tenn 244 500 5000 KGBU Ketehikan, Alaska 400 500 W D RC New Haven, Conn 283 500 W K BZ Ludington. Mich 200 15 KTSA San Antonio. Texas 265 2000 WDSU 1227 W KEN Y 207 750 KGBX st. Joseph, Mo 288 100 213 5 New Orleans 250 KTUE Houston. Texas WDWF-WLSI WKJC LancastsBUffalo,er, Pa 252 50 KGBY Columbus, Nebraska 222 50 KTW Seattle. Wash 395 1000 Cranston, R. I 248 250 213 100 WDZ Tuscola, Ill. (daytime) 278 100 W KRC Cincinnati, Ohio 246 500 KGBZ York. Nebraska KU Longview. Wash 200 10 WK Y K G C A Decorah, Iowa. 248 10 WEAF ?Bellmore, N. Y "492 50.000 Oklahoma CttyOkla 288 150 KU OA Fayetteville. Ark 297 1000 WEAN W LAC Nashville, Tenn 225 KGCB Oklahoma City. Okla 216 50 KUOM Missoula. Mont 461 500 Providence, R. I. 275 500 5000 KGCH Wayne, Nebraska 294 250 WEAO Columbus, Ohio 283 750 W LAP Louisville, Ky 268 500 KUSD Vermillion, So. Dak 484 250 WLB Minneapolis. Minn 246 500 KGC1 San Antonio, Texas 220 250 KUT Austin. Texas 232 500 WEAR Cleveland, Ohio "400 1000 KGCN Concordia, Kansas 208 50 WE BC Superior, Wie 242 1000 WLBC Muncie, Ind .. 210 50 KV I Tacoma. Wash 283 250 W LBF Kansas City. Kansas.. 210 KGCR Brookings, So. Dak 208 15 KVL Seattle. Wash 273 100 WEBE Cambridge, Ohio 248 10 50 KGCU Mandan. No. Dak 240 100 WEB Q Harrisburg, Ill 224 15 W LB Petersburg, Va 214 100 KVOO Tulsa, Okla 949 .5000 WLBH Farmingdale. N. Y 232 30 KGC X Vida. Montana 244 10 KVOS Bellingham. Wash 210 250 WEBR Buffalo, N. Y 242 200 KG DA Dell Rapids, So. Dak WEBW Beloit, Wis.:.. 258 500 WLBL tStevens Point. Wise 333 1000 KWBS Portland. Oregon 200 50 WEDC Chicago, WLBO Galesburg, Ill 247 100 (daytime) 254 15 KWCR Cedar Rapids, Iowa. 240 100 Ill 242 100 KG DE Barrett. Minn 205 50 WEDH Erie, Pa 219 30 WLBR Rockford, Ill 248 15 K W EA Shreveport. La 213 100 WEEI Boston, Mora WLBV Mansfield Ohio 207 50 KG DM Stockton. Calif. 217 10 KWG Stockton. Calif 345 100 508 500 KG DP Pueblo. Colo. 224 10 WE HS Evhnston, Ill 216 100 W LB W Oil City. $a 294 500 KWJJ -. Portland. Ore 250 50 W LB KGDR San Antonio. Texas 207 15 234 1000 WEMC Berrien Spas., Mich 484 1000 Long Island City, N.Y 204 100 K W K St. Louts. Mo WENR see WBCN Mountain, Mich 210 KGDW Humboldt. Neb 294 100 K W KC Kansas City. Mo 222 100 WLBY Iron 50 KGDY Oldham. So. Dak 207 15 WEPS Gloucester. Mass 297 100 WLBZ Dover- Foaeroft, Me 208 250 K W K H Kennonwood, La 395 3500 WEVD Woodhaven, KGEF Los Angeles. Calif 263 1000 K W LC DMorah, Iowa 248 50 N. Y 246 500 WLCI Ithaca, N. Y 248 50 KGEK Yuma. Colo. (day) 263 50 WEW St. Louis, Mo. (day) 353 1000 . 395 500 Lexington, Mara 218 K W SC Pullman. Wash WFAA Dallas. Texas 545 500 WLEX 50 KG EN El Centro. Calif 225 100 KWTC Santa Ana. Calif 273 100 WLIT Philadelphia, Pa -405 500 KGEO Grand Island. Neb 205 100 WFAN Philadelphia. Pa 224 500 K W W G Brownsville, Texas 278 500 WFBC Mass 211 100 KGER Long Beach. Calif 216 100 KXA Seattle, Wash 535 500 Knoxville, Tenn 234 50 WLOE Chelsea, ROES Central City. Neb 204 10 220 250 WFBE Cincinnati, Ohio. 246 250 WLS ?Chicago Ill "345 5000 KXL Portland. Ore Pa 268 100 KGEW Fort Morgan. Colo 219 100 KXRO Aberdeen. Wash 224 50 WFBG Altoona, WLSI See WDWF KGEZ Kalispell. Montana 294 100 361 1000 WFBJ Collegeville, Minn 273 100 KYA San Francisco, Calif W FB L Syracuse. N. Y 258 750 WLTH Brooklyn N Y 256 250 KG FF Alva. Oklahoma 205 25 KYW Chicago, Ill 534 2500 Ohio 428 KG Oklahoma Okla KIM Oakland. Calif 231 100 W FB M Indianapolis. Ind 275 1000 W L W ?Cincinnati 5000 Glendale, Calif 263 250 NAA Arlington. Virginia.. 1000 WFBR Baltimore, Md 244 250 W L W L ?Kearny. N. J.. 370 5000 434 W FC I R. 242 100 KGFI San Angelo. Texas 220 15 A D 231 25 Pawtucket, I WMAC Caaenovia, N. Y 225 500 WA Cincinnati. O WFDF Flint, Mich 273 100 KGFJ Los Angeles. Calif 213 100 WAAF Chicago. Ill 389 500 WMAF So. Dartmouth. Mass 428 500 KGFK Hallock. Minn 224 50, 268 250 WFI Philadelphia, Pa 405 500 WA A M Newark, N. J 261 "Martinsville, N. Y 545 750 KGFL Raton, N. M 222 50 WAAT Jersey City. N. J 246 300 W F I W Hopkinsville, Ken 1000 W MAK KGFW Ravenna. Neb 297 10, WAAW Omaha, Neb. (daytime)441 500 WFJC Akron, Ohio 227 500 W MAL Washington, D. C 242 500 Pierre. S. D. (day) 254 '2500 WFKD Philadelphia. Pa 248 50 Columbus, Ohio 234 50 KGFX 200 WA BC Richmond Hill, N. Y 309 517 750 W MAN KGGF Ficher, Okla 207 100 WABF Kingston, Pa 205 250 WFLA Clearwater. Fla WMAQ 'Chicago, Ill "447 2500 KGGH Cedar Grove. La 213 100 WGAL Lancaster. Pa 252 10 50 WABI Bangor. Me. (Sundays) 389 246 W M A Y St. Louis. Mo 234 100 KGHA Colo 210 500 WA BO See WGBB Freeport, N. Y 155 WHEC Tenn 229 10 Ga 270 509 KG H B HonoluPueblo, lu, Hawaii 227 250 WABY Philadelphia, Pa 248 50 WGBC Memphis. WMAZ Macon, KGHF Pueblo, Colo 210 250 WABZ New Orleans, La 238 50 WGBF Evansville. Ind 236 255 WMBA Newport, R. I 204 100 KGHG McGehee, Ark WA DC Akron, Ohio 238 1000 W GB I Scranton. Pa 231 250 Mich 244 100 York, N. Y 349 500 W MBC Detroit, KGHI Little Rock, Ark 261 15 WAFD Detroit. Mich 231 100 W GBS ?New D Peoria Heights. Ill 205 239 KGHL Billings. Mont 222 250 225 50 222 10 W M B WAG IA Royal Oak, Mich WGCM Gulfport. Miss Beach, Fla 384 500 KGHX Richmond, Texas 52 WA 1U ?Columbus, Ohio 283 5000 J 268 250 W MBF Miami WGCP Newark. N. 220 50 KG IF (portable) Nebraska 217 8 WALK Willow Grove. Pa 201 50 242 500 WMBG Richmond. Va Little Rock, Ark 1000 WGES ?Chicago, Ili 204 100 KGJF 250 W A P I Auburn, Ala 341 Mich 278 750 WMBH Joplin, MO KG KB Gotdthwaite, Texas 280 WASH Grand Rapids. Mich 256 250 WGHP ?Fraser, Ill 263 5000 KG KO Wichita Falls, Texas '... 250 WBAA West Lafayette, Ind.. 273 500 WGMS Minneapolis, Minn 246 500 WMBI ?Addison,
*Allowed higher daylight power Sta dard or constant -frequency transmission. I Remote Control.
www.americanradiohistory.com Radio News for November, 1928 431
Radio Radio Radio I Radio BROADCAST STA. (e Oa BROADCAST STA. '« ;ÿ Call BROADCAST STA. oe O. BROADCAST STA. 4. l¡ Location ;f 23 Latter Location 3f ¿; Letter Location 3 ¿= Lett n Location 3f :;
WMBL Lakeland, Fla 229 100 WOBU Charleston R. Va.... 268 250 WRBC Valparaiso. Ind 238 250 WSGH Brooklyn, N. Y 227 50 WMBM Memphis, Tem 210 10 WOC Davenport, Iowa 375 5000 WRBH Manchester, N. H 500 WS IX Springfield Tenn 250 15 WMBO Auburn. N. Y 220 100 WOCL Jamestown, N. Y 224 25 W RBI Tifton. Ga 222 50 WSKC Bay City. Mich 273 25 WMBQ Brooklyn. N. Y 204 100 WODA Paterson. N. J 294 1000 WRBJ Hattiesburg Miss 250 10 WSM Nashville. Tenn 337 50500 WMBR Tampa, Fla 252 100 WOI Ames, Iowa 265 1000 WRBL Columbus, Oa 258 50 WSMB New Orleans, La. 297 76 WmBS Lemoyne, Pa 234 250 WOKO Beacon, N. Y 216 500 WRBQ Greenville, Mies..,, 275 100 WSMK Dayton, Ohio..... 297 20 517 WOMT Manitowoc. Wis 222 100 WRBT Wilmington, N. C 227 50 WSPD Toledo. Ohio 240 250 wMC Memphis. Tenn 5000 Gastonia. N. C 50 WSRO W MCA tNew York. N. Y 370 500 WOOD tGrand Rapids Mich 261 500 WRBU hllddletown. Ohio 236 10 LAMES Boston. Mage 211 50 WOQ Kansas City. Mo 341 500 WRB W Columbia. S. C 15 WSSH Boston, Mass 288 10 WMPC Lapeer. Mich 234 30 WOR tKearnY, N J 422 5000 WRBX Richmond. Va _a2 0 WSUI Iowa City. Ia. day) 476 50 WMRJ Jamaica, N. Y 207 10 WORD tRatavia, III 252 5000 WRC Washington, D. C 468 500 WSUN St. Petersburg. la 517 75 o W MSG New York, N. Y 236 500 WOS Jefferson City, Mo 422 500 W REC tMemp ls, Tem 250 500 WSVS Buffalo. N. Y 204 5 0 WNAC -WBIS Boston, Mass,.,, 461 500 WOV tNew York. N. Y 294 1000 WREN Lawrence. Kan 254 750 WSYR Syracuse, N. Y. 294 50 O WNAD Norman. Okla 240 500 WOW Omaha, Nebr 508 1000 WRHF Washington.D.C.(day) 322 150 WTAD Quincy, Ill 236 25 0 WNAT, Philadelphia. Pa 288 100 WOWO Fort Wayne, Ind 229 2500 WRHM tMinneapolis, Minn 261 1050 WTAG Worcester, Masss 517 25 0 224 WRJN Racine, Wie 248 50 WTAM Cleveland. Ohio... 400 350 0 WNAX Yankton. S. D. (day) 303 1000 WPCC Chicago, Ill 500 p WNBF Endicott, N. Y 207 50 WPCH tNew York. N. Y 326 500 WRM Urbana, I0. 273 500 WTAQ Eau Claire, Wis 254 50 WNBH New Bedford, Mass 261 250 WPG Atlantic City. N. J 273 5000 WRK Hamilton. Ohio 205 100 WTAR- WPOR Norfolk. Va 236 50 WNBJ Knoxville, Tenn 207 50 WPRC Harrisburg, Pa 210 100 WRN Y tNew York. N. Y 326 500 WTAS See WGN WNBO Washington, Pa 211 15 WPSC StateCollege, Pa. (day) 300 500 WRR Dallas, ex 461 500 WTAW College Station, Tex 484 50 WNBQ Rochester, N. Y 205 15 WPSW Philadelphia, Pa 207 50 WRUF Gainesville, Fla 203 5000 WTAX Streator, Ill ... 248 5 WNBR Memphis. Tenn 229 100 WPTF Raleigh. N. C 545 1000 WRVA Richmond, Va 254 10X: WTAZ Richmond. Va 220 1 5 WNBW Carbondale, Pa 200 5 WQAM ML.mt. Fla 384 750 WSA I tCinclnnati, Ohio 361 5000 WTFF Mt. Vernon Hills. Va 20310,000 WNBX Springfield. Vt 242 10 WQAN Scranton, Pa. 231 250 WSAJ Grove City, Pa 224 250 WTFI Toccoa, Ga 210 00 N. Y 232 10 WQAO -WPAP tCliffslde. N. J 395 500 WSAN Allentown, Pa 222 100 WTHS Atlanta, Ga 227 _ 0(I WNBZ Saranac Lake. WSAR Fall River, Mass 213 250 WTIC 535 5 00 WO Newark, N. J 268 250 WQBC Utica, Mies. (day). 216 225 Hartford, Conn WQBJ W. Va 40 05 WSAZ Huntington. W. Va 250 100 WTMJ Milwaukee. Wle 294 1000 WNOX Knoxville, Tenn 265 1000 Clarksburg. Atlanta. 476 N. C 224 500 WQBZ Weirton, W. Va 250 60 WSB Ga 1000 WWAE Chicago. III 227 5 00 WNRC Greensboro. Chicago, Ill 232 100 WWJ Detroit, 353 ] 000 WNYC New York. N. Y 526 500 WRAF Lanorte. Ind ?fig 100 WSBC Mich Tex 280 5000 WSBF St. Louis, Mo 258 250 WWL New Orleans, La 246 500 WOAI San Antonio, WRAK Erie, Pa ?19 30 WSBT South Bend, Ind 400 500 WWNC Asheville, N. C 297 100 WOAN Lawrenceburg, Tem 240 500 Pa 238 100 WSDA WSGH wOAX Trenton, N. J 240 500 WRAW Reading, ... See WWRL tWoodelde. N. Y 200 10 ans 1s WRAX Philadelphia. Pa 213 250 WSEA Portsmouth. Va 263 500 WWVA Wheeling. W. Va 517 25 o transmission. Allowed higher daylight power. Standard or constant-frequency tRemote Control LIST OF CANADIAN BROADCAST CALLS Alta 357 1000 CJ R M Moose Jaw, Sask 297 500 CKOW CFAC Calgary. Alm 435 500 CHCT Red Deer, Toronto, Ont. 357 5n0 CFBO St. John. N. B 337 50 CHGS Summetsslde, P. E. I 268 25 CJRW Fleming, Sask 297 500 CKPC Preston Ont 298 C H LS Vancouver, B. C 411 50 CJSC Toronto, Ont 517 500 CKPR Midland. Ont 268 0 CFCA Toronto, Ont 357 500 Que CFCF Montreal, Que 411 CHMA Edmonton. Alta 517 250 CKAC Montreal, 411 1200 CKSH St. Hyacinthe Que. 297 b0 Falls. Ont 500 1250 CHML Mt. Hamilton, Ont 341 50 CKCD Vancouver. B. C 411 50 CKUA Edmonton. Alta 517 55' CFCH Iroquois Toronto. Ont 517 500 C KCI QJebee. Que 341 23 C K W X Vancouver. B. C 411 CFCL Toronto, Ont. (Sunday) 517 500 CHNC 100 1800 CHNS Halifax, N. 5...... 322 500 C KCK Regina, Soak 312 500 C K Y Winnipeg, Man 384 500 CFCN Calgary, Alta 435 Quebec, Que 341 5 CNRA Moncton, N. B 976 CFCO Chatham. Ont 476 500 CHRC CKCL Toronto, Ont 517 500 500 CFCT Victoria, B. C 476 CHWC Regina. Sask 312 15 CKCO Ottawa. Ont 435 100 C RC Calgary. Alta 435 500 312 100 CHWK Chililwack, B. C 248 5 CNRE Edmonton, Alta 517 5'0 CFCY Charlottetown. P.E.L. Montreal, Que 411 750 CKCR Brantford, Ont 297 50 CFJC Kamloops. B. C 268 15 CHYC Quebec, Que 341 50 C NR NI Montreal. Que 411 1600 297 50 CJBC Toronto, Ont..517-357-312 500 CKCV CFLC Prescott, Ont Sask 312 500 Vancouver. B. C 411 50 CHRO Ottawa. Ont 435 550 Ont. 268 20 CJBR Regina. CKFC CFMC Kingston, 25 CJCA Edmonton.Alta 517 C KG W Bowmanvllle. Ont 312 5000 CNRQ Quebec. Que 341 50 CFNB Fredericton N. B 248 250 Saskatoon. Seek 330 500 CJCJ Calgary, CKLC Red Deer, Alta 357 1000 C RR Regina. Sask 312 500 CFQC CJGC London, Ont 330 500 330 500 Toronto, Ont 312 1 CKMC Cobalt. Ont 248 100 CNRS Saskatoon, Sask CFRB Sask 476 500 Ont..... 268 CJ G X Yorkton. CKMO Vancouver, B. C. 411 C N RT Toronto. Ont 357 500 CFRC Kingston, 250 CJHS Bask 330 250 Calgary. Alta 435 Toronto. Ont 517 500 C RV Vancouver. B. C 291 500 CHCA 476 500 CJOC SethbridgeLethbridge Alm 268 50 CKNC CHCK Charlottetown. P.E.I CJOR Sea Island, B. C 291 50 CKOC Hamilton. Ont 341 100 CNR W Winnipeg. Man 384 500 CHCS Hamilton. Ont. 341 LIST OF SHORT -WAVE STATIONS OF THE WORLD U. S. Short- Wove Stations wilt prefix their experimental calls with W or K after October 1, 1928; and others with their allotted national totters on or before January 1, 1929.
Radio Bad.- Radio Call BROADCAST STA. Call BROADCAST STA. Call BROADCAST STA. Location Letten Location Letters Location
AFRICA HOLLAND SWEDEN PCI, Eindhoven 31.4 30,0000 SAJ Karisborg 47.00 la Johannesburg, U. S. Akira_ _ 3(Ó.O00 4.000 PCKK Kootwllk 16.00 SMHA Stockholm 41.00 ¡LO Nairobi, Kenya h PCLL Kootwllk 18.10 32.000 AUSTRALIA PC PPM Kootwwilke 16.50 SWITZERLAND 32.50 PCRR Kootwilk 37.00 2BL Sydney PCTT Kootwijk 21.00 EH90C Berne 3200 2FC Sydney 32.00 EH9XD Zurich. 85.00 and 32.00 2ME Sydney 28.50 PCUU The Hague 37.00 SAR Melbourne 55.00 3AR Melbourne.. 55.00 ITALY UNITED STATES 3LO Melbourne 32.00 32.90 iAX Rome 45.00 Pittsburgh, ... 62.50 6AG Perth. West Australia IA Y Rome 45.00 KDKA (6XK) East Pa.... 40,000 IMI Milan 45.00 (8X8, SEP- portable) AUSTRIA 42.75 ..... ,:.:,,:,::,,:,,:,,:,,:,,:,,:,,:,,:,, :,,::,:,,::,:,,,,,,,,,,.,,, ,,,,,,,:,,::, ,,,,,,,,,,,,,,, KEJK (CRAN) Loe Angeles, Calif . 105.90 250 LATH Vienna 37.00 KEWE Bolinas. Calif 14.10 Vienna 22.20 KFPY (7XAB) Spokane. Washington 105.90 100 short -wave broadcast KFQU (6XBH) Holy City, Calif 31.00 50 THIS list of the 53.00 BELGIUM stations throughout the world is not 63.00 EB4A2 Brussels 42.00 300 complete, although we bave endeavored to 106.00 list every station of whom we have heard KFQZ (6XAL) Hollywood. Calif 108.20 .50 CANADA reports; since in many Cases reliable in- KFVD (6XBX) Culver City. Calif 105.00 50 Los Angeles, Calif 105.00 50 CF Drummondville, Quebec 32.00 formation about the programs, wavelength KFWB (6XBR, auto) 25.60 2,01X1 be 40.00 CJRX Winnipeg, Man and power of the stations cannot even KFWO (6XAD) Avalon, Calif 53.07 100 obtained from the stations themselves. KGER (6XBV) Long Beach, Calif 48.86 DANTZIG - (See page 456.) KGB San Diego, Calif 65.18 40.00 KGDE Barrett, Minn 40.00 50 EKaZZZ Dantzig . . . . . - - . KGO l6XAX, 6XN) 10 to 40 10,000 KHJ (6XAU) Loe Angeles. Calif...... 104.10 50 DENMARK KJBS (SXAR) San Francisco, Calif.... 61.00 50 7MK Copenhagen 32.90 'd10 JAPAN KJR (7XC, 7X0) Seattle, Washington 105.20 250 7RL Copenhagen 42.12 and 84.24 250 J FAV Taipeh. Formosa 39.50 KMOX St. Louis, Mo. .... 49.00 15 JHBB Ibarakiken 37.50 5.000 KMTR Lott Angeles, ('alit 108.20 250 ENGLAND J IPP Tokio 20.00 KNRC (6XAF) Santa Monica. Calif..... 108.20 100 JKZB Tokio 20.00 KNX (6XA) Los Angeles. Calif 107.10 100 15W Chelmsford 24.30 15.01x) IAA Iwatsuki 40.00 KOIL (9XU) Council Bluffs, Iowa 61.06 500 2NM Catcrham 32.50 KWE -KEWE Bolinas, Calif ...... 14.10 CBS Rugby 24.40 KWJJ (7XAO) Portland, Oregon 53.54 100 JAVA WAAM (2XBA) Newark, N. J 65.18 0 FRANCE Malabar 33.00 WABC (2XE) Richmond Hill, N. '1' 58.50 500 ANE Bandoeng 15.93 (Yacht 111U -1, 2XAO) Radio LL Paris 61.00 500 ANF Malabar 56.00 80.00 51X) WAJ Rocky Point, 22.48 FBAV Nogent ANH Bandoeng 17.00 MY 250 Radio Vitus Paris 37.00 1,500 Batavia 46.50 WBRL (1XY) Tilton, N. H 100.00 Radio Lyon Lyons 40.00 50 WCGU (2XBH) Brooklyn, N. Y 54.00 150 YN Lyons 8.00 3,x0 WCSH (1XAB) Portland, Maine 63.79 250 Nancy 15.50 '00 MEXICO WCX Pontiac. Michigan 32.00 75 ' 2.48 FW4 Ste. Astise 24.50 XC51 Mexico City 44.00 WEAJ Rocky Point, N. Y WEAO (9XJ) Columbus, Ohio 54.02 25 MOROCCO WGY (2XAF) Schenectady, N.Y.. 31.401 GERMANY (2XAD) Schenectady, N. Y 21.96 AFI Konigswusterlumsen 14.00 AJN Casablanes 51.00 AFT Xonigswusterlansen 14.00 WHK (8)(F) Cleveland. Ohio 66.04 500 AFU KonllSwusterbaustn 14.00 NORWAY WJR -WCX (CXAO) Pontiac, Michigan 32.00 AFK Berlin 45.30, 93.12, 41.50 LCHO Oslo 33.00 WIZ New Brunswick, N. J 43.45 H EA Nauen 11.00 WJZ (3XL) New York, N. Y 59.96 30,000 Nauen 1350 U. S. S. R. (RUSSIA) WLW ($XAL) Cincinnati, Ohio 52.02 25 AGC Berlin 17.20 RDRL Leningrad 28.50 49.061' 250 AGJ Nauen 56.70 RDW Moscow WNAL (9XAB) Omaha. Neb 105.00 50 AGK Nauen 11.00 RFM Knabarovak (Siberia) 7020 12,000 WNBT Elgin. Ill. (Time Signals) 35.50 500 LA Langenberg 43.90 37.00 J 46.48 RA19 Tomsk (Siberia) WND - Ocean Township, N. POF Nauen 11.00 WOR (2XAQ) Kearny N J 65.40 50 Nauen SPAIN 22.80 1,000 18.10 WOWO Fort Wayne. Ind POZ auen LAM Madrid 30.70 WRNS* (2XAL) New York, N. Y 30.91 500 Konlgswusterhausen 52.00 WTFF Mt. Vernon, Va 56.00 Stuttgart 41.00 RAE55 Barcelona 1
www.americanradiohistory.com 432 Radio News for November, 1928
lock switch. A buzzer sounded; all the lights winked out, except a single brilliant spotlight trained upon the speaker's was plat- JT a tense moment for the thousands ing in everything that was bigger and bet- form; upon three monitoring television gathered there in the great bowl of ter, had realized that Southern California screens suddenly appeared a vista -of huge the Coliseum -those thousands of in- faced a future power famine if means of dynamos against a background of switch - trepid film fans who had risked crum- expansion were not provided; how he had studded panels jewelled with control pled fenders, lights; crushed hats, comfort, and initiated and backed the movement for a and in the loud speakers rose almost an ascending life itself, simply to gain a glimpse great public -owned power system; how whine as tons of water, of at surging through the that great man who is not only the chief every step he had been hampered by the great turbines, whirled the idol mighty gener- of the film fans of the world, but a insidious machinations of a certain power ators faster and faster. far -famed philanthropist as well. It was an corporation, which saw in this project The radio audience now equally beheld a strange interesting moment for millions of dangerous competition; and how, even after sight. Down the middle of the happy families television everywhere, who, through an overwhelming majority at the polls had screen ran a narrow line, the agency separating two of television, were seeing with demonstrated the public's confidence in the distinct pictures. On the equal clearness left, the Mayor from the privacy of their project, material had mysteriously disap- and Harold Dare were acknowledging the own homes every detail in the spectacle peared from the site, important shipments storm of applause which swept which was the Coliseum; taking place in Los Angeles' had been unaccountably delayed or side- on the right appeared a panorama great amphitheater. of switch- The palpitating hearts tracked, and a host of sinister occurrences boards and controls, at which operators of countless devoted film fans throbbed in had demonstrated powerful influences at were bringing up the Wolf Creek line into unison to realize that the deep, vibrant, work to undermine the screen star's phase; while from resonant great the loud speaker issued chest tones issuing from the loud work of public benefaction. But that same a hum of busy dynamos against speaker were a back- the voice of him whom a indomitable courage and unswerving devo- ground of frantic applause. The Dare tech- whole world idolizes as one of supreme dar- tion to the public weal that have made nicians had scored ing, another succes. By of unsurpassed generosity, and of a Harold Dare the outstanding world figure masking opposite halves of breadth, depth, the fields of and thickness of character that he is, had ever sustained him through two television transmitters, one at Wolf that mark him as the biggest and best all these crises and carried him onward and Creek and another film at the Coliseum, and by hero in the industry. The eyes and upward to his goal. Success was his combining the cars at currents as they were fed of;the whole world were turned toward last! This key, when turned in the into the transmitter that little little broadcasting the event, platform in the blaze of a hun- lock on the control panel before the speak- the two scenes were reproduced dred spotlights, where Harold side by Dare, Flicker er's table, would send out an electrical im- side upon the receiving- screens, much as Films' famous favorite, was concluding the pulse over many miles of copper wire, in the double exposures common in motion - few well-chosen remarks with which he was through the city and across desert wastes, picture photography. bestowing upon The sound currents Southern California a boon over plain and mountain, to a structure of were simply superimposed upon one another, 'for which generations to come would ever concrete and steel located among the relative 'bless the deso- proportions being regulated by :Iris name. . bate;, ragged- fastnesses of the high Sierras. operators at the conventional gain controls. : furo you, Mr. Mayor, as representing the Her'; at the head of a great blue lake The television peóple of feci circuits had required many the Southland, I present this key from the melting snows, tons of water held days of careful balancing and adjustment the key..-to progress, - the key to prosperity, chained by man's masterful mind would be before the synchronization had been per- the Ivey to that great future which shall be released to do his bidding. 'Down fected; Southern from the ultimate success was indeed an California's. May this be merely the great turbines whirled by the enslaved engineering triumph. the beginning of a long advance, onward giant.wòuld coúrse a cataract of power, and of Suddenly Harold Dare, bowing and ac- uípward, bigger and better, toward that electrical energy which, guided knowledging world by three with matchless ease the tre- supremacy which is the goal of every tiny threads..of copper flung across gorge mendous clamor true booster. of applause of that enor- Here is power, Mr. Mayor. and river, would speed the wheels of in- mous audience, sensed lay it ever that something was be used for the greatest good dustry to an activity heretofore undreamed. wrong. He turned -and stood transfixed. to the greatest number." "To you, Mr. Dare," concluded the Mayor, The applause of thousands suddenly died; - Amid a thunder of applause, the Mayor in a final burst of eloquence, with a sweep- the smile of the Mayor faded from his took the little gold face; key and held it up be- ing gesture which summed up all the ad- for the silver screen of the televisor fore the eye flickered of the televisor that all the miration, _respect, and : gratitude due so and was dark. millions in that vast outside audience might great a public benefactor, "Southern Cali- For a few endless seconds, Harold Dare see. In n long eulogy of fulsome tribute, fornia owes a. debt it can never repay! and the Mayor stared, amazed, aghast, he traced for his audience in- the progress of "On behalf of the citizens. of the City of credulous. An operator hurried over from Harold Dare's activities in this latest mani- Los Angeles and of all Southern California the control box and a festation of spoke few words in the great screen star's bound- as well, I accept this key; to their benefit, a low voice. The Mayor gasped and paled; less benevolence and whole -souled public and that of posterity, I hereby dedicate the but dauntless Harold Dare stepped calmly spirit. He told how Harold Dare, ever new Wolf Creek power line." to the watchful front and addressed the puzzled of the public welfare, ever lead- He inserted the little gold key in the audience.
www.americanradiohistory.com Radio News for November, 1928 433
"Friends, there is no use in keeping the cipled persecutors of the public's dauntless position several hundred feet in the air. truth from you. The Wolf Creek line is champion. in their hearts was developing a fear that dead." Who might be behind these dark and some error had been made in the design. it murmur of amazement, mingled with devious deeds? One none was whispered The insulators used had been tested under indignation, swept the great gathering. Har- about with steadily growing persistency. conditions so much more severe than any old Dare raised his hand for silence. Remembering the countless similar outrages met in practice that . failure was unthink- "Friends, before you judge or blame, let perpetrated in the past by the monster, able. Yet nothing seemed to stop the mad me tell you a few facts about the construc- the public intuitively suspected Dandy Di- surge of half a million volts across this one tion of the Wolf Creek line. The wires avolo, that arch super -villain of the Flicker apparent weak spot in the whole Wolf are run in duplicate -two complete sets Films, who had ever pursued Dare with Creek line. Frankly, they were baffled. upon each tower. If an insulator should increasing relentlessness through the super- The new insulator was hoisted to its place fail, or a wire break, the other circuit would lative Flicker Films, and in real life as well. under the strict scrutiny of world- famous still maintain service. There is not one Dare himself did not doubt that his arch- electrical engineers. It had been given a chance in a million that both lines should enemy was behind this plot, but his de- thorough test and was apparently electric- fail at the saute moment -and of all tuo- tectives were unable to find any trace of ally perfect. 'l'he voltage was applied gradu- 'meats, the very moment when failure would the villain, who had left for parts unknown ally. At Wolf Creek station, a group of mean the greatest personal blow possible, to spend a short vacation between pictures. engineers watched tensely the meters reg- a spectacular debacle calculated to shake At two o'clock the next afternoon cante istering line conditions, while at the tower the confidence of the public in this project news that rocked all Southern California. itself, motion- picture cameras, equipped with and turn the admiration of the world to The trouble in the Wolf Creek line had telescopic lenses, made slow- motion pictures ridicule. Let me remind you, ladies and been located. Three insulators of the six of the insulator from various angles. At gentlemen, that although this line, strung on a single tower located on the edge of length the line was carrying its full load. from sturdy towers founded upon eternal a cliff above a deep valley had shattered, For moments the engineers watched, while rock, is made to withstand the ravages of allowing the wires to fall and short- circuit reel after reel of film ran swiftly through the centuries, a single blast of dynamite both lines. Working in continuous shifts, the cameras. might easily send one massive tower top- repairmen replaced the insulators in a few Suddenly the meters at Wolf Creek quiv- pling into a ravine, doing damage it would hours. ered. As suddenly the needles shot across take days to repair. As you all know, The new insulator liad lasted hardy ten the scale; great circuit -breakers tripped; there are forces bitterly opposing this great minutes. The startled linemen had scarcely an arc flared and was quenched; and the project; they could have chosen no better. gathered up their tools when a terrific arc generators whined at high speed as the time to strike than now. No apology I rent the air. One huge insulator, then a load was removed from the line. The could make would suffice; yet I promise second, shattered into a'thousand pieces, frightened engineers stared helplessly at you that I shall not sleep nor rest until as if struck by a giant's hammer. Two long one another. The Wolf Creek lines were the fiendish perpetrator of this crime against cables swung together and were welded dead! humanity is brought to justice!" into one; then as the intense heat melted It was an old story the engineers saw The ovation these words received was the stranded copper, the severed wires re- enacted before their eves as a few hours tremendous. The thousands went forth with traced tattered shreds of flame as they later they sat in the projection room of the warmest sympathy for the heroic stand slipped along the steel tower to the ground. the Dare laboratories at Hollywood. A of their great friend and protector. Not New insulators were rushed from the tongue of flame suddenly bridged the gap a woman but sighed a little in admiration nearest supply station. Engineers hastened between a cable and the tower. It grew for this fearless hero who thus smiled coolly to the spot to make observations. While to a broad ribbon, and slowly two great in the very face of disaster; not a man but it was ostensibly their opinion that both strings of bell- shaped insulators separated clenched his fist and protruded his jaw insulators had developed flaws, possibly from their mountings amid a shower of with just indignation toward the unprin- through strain while being hoisted to their large fragments of porcelain. As if in sympathy, another insulator on the other side of the tower also burst hito splinters of porcelain and the three floated leisurely to ground, while the cables tangled, melted. and dropped out of sight in the canyon. (Continued on page 479)
"d million people gazed horror -stricken; for to the topmost cross -arm of the /rge tower clung two lining skeletons- skeletons whose hands clutched pliers, skeletons that shouted hoarsely for lights!"
www.americanradiohistory.com 434 Radio News for November, 1928
9 0
-1 1`I f a ; a s New ün a f jeer,,, -
tential to 110 volts Two-Way Regulator Corrects for the operation of to the lamp socket, and also with a 110- Line -Voltage Variation the radio receiver, regardless of whether volt receptacle for the plug of the power the line -voltage is above or below this value; transformer; the only adjustment THE small box -shape device is a knob illustrated whereas resistors are capable only of re- which operates an eight -point switch. in this column is a voltage regulator for ducing the voltage. Secondly, the unit The way in which the unit is use in connection with connected radio receivers. It has a sufficiently wide range to cover all is shown in the schematic wiring diagram. conditions; it will increase the voltage to Another illustration shows the mechanical normal value from as low as 90 volts, or it construction of the combination switch will decrease the voltage to normal from which automatically connects the voltage - as high as 130 volts. Thirdly, there are indicating buzzer when the voltage regu- eight voltage taps, thus providing a ver,v lator is being adjusted. It will be noticed close adjustment. And fourthly, it is highly that the shaft turned by the adjustment efficient, as it regulates the voltage by re- knob is connected to the contact arm of actance, rather than resistance. SW1 and that, as the shaft is turned to The appearance of the device is clearly the right, the contact arm of SW1 is turned shown in the accompanying picture; it is and the switch SW2 is closed. However, housed in a metal box 41/4 x 414 x 3'''% as soon as pressure is removed from the inches and weighs 3 pounds. It is pro- knob, It spring opens switch SW2, thus vided with a cord and plug for connection disconnecting the buzzer. Manufacturer: R. B. 3!. Manufacturing Company, Logansport, Ind.
To obtain 110 -volt current from a variable or non -standard lighting supply, plug the re- New Short -Wave Plug -In Coils ceiver's power -unit lead in at B on this device, and insert C in a light -socket. Adjustment is Small and Rugged made by knob A, as shown in the diagram at A well -known manufacturer the right. of short -wave receiving equipment has developed some 5W 1 new plug -in coils which are small and of has been designed to correct the house- very rugged construction. The coils are supply voltage to 110, 5W 2 TO 110V. A. C. the potential usually sold in sets of three, as shown in the illus- required by electric sets. It will oper- tration. They provide a receiver with a ate in any A.C. -m41 circuit, provided the voltage wavelength range of 15 to 130 meters. is not greater than 130 nor less than 90, and VIBRATOR A complete set of these coils consists of has 60 it an output of watts, which is am- three interchangeable coils, a suitable base ple for the operation of the average set. and an adjustable primary, which is It is not difficult to appreciate the im- mounted on the base. In each case the portance of an A.C. line -voltage regulator, interchangeable coils have two windings, a for the chief cause of dissatisfaction with secondary and tickler. The coils may be electric receivers has been due to the short SPRING used in the standard fixed- tickler, capacity- life of the tubes. It was first thought by 5W 2 controlled regenerative circuit, with a 140 - the experimenters that this condition re- mmf. variable grid -tuning condenser and a sulted from poorly -designed .tubes, but in- 250 -mmf. variable feed -back condenser. vestigation has shown that variations in With this arrangement the smallest coil the 110 -volt house -supply current usually } provides a wavelength range of 15 to 33.5 are responsible for overloading the filaments 110-V. RECEPTACLE meters, the next largest coil has a range and reducing tube life. A. majority of the FOR POWER TRANS- of 31.5 to 68 meters, and the largest coil FORMER. power transformers available for heating has a range of 57 to 133 meters. Also, coils tube filaments are designed for 110 -volt T he auto -transformer steps the voltage either of the same design are available for higher operation and an increase in the input volt- up or down, as required. The correct setting and lower wavelengths. age will cause a proportional increase in is indicated automatically by the buzzer; SW2 functions only during the operation of adjust- The picture immediately below clearly shows the output. Therefore, in cities where the ment. the skeleton construction of the coils. The house potential rises to 120 and 130 volts during the evening, the tube filaments oper- ated with A.C. are dangerously overheated. On the other hand, insufficient power is frequently the cause of poor reception. The voltage- regulating device illustrated on this page provides the broadcast listener with a very simple method of regulating the input voltage to a receiver. It is a simple auto-transformer, equipped with a special A.C. buzzer which vibrates when the potential applied to the receiver reaches 110 volts. The interesting feature of the regulator is that the voltage- indicating buz- zer operates automatically during adjust- ment, but is turned off by the removal of the operator's hand from the adjustment knob. The compactness and convenience of these coils for the short -wave operator may be readily seen. Among other advantages it possesses, this The secondary- tickler coil at the left is for the 15 -33.5 -meter range, and that at the right for 3L5 -68 meters. The 57. 133 -meter coil is shown plugged into the base; to which the primary is regulator will correct the house -supply po- permanently attached, as it is the some in all combinations.
www.americanradiohistory.com Radio News for November, 1928 435 secondary winding consists of the necessary Radio Outlets Attractive Battery -Cable Connector number of space -wound turns of enameled wire. The tickler winding is self-supporting For Home Wiring Handy for Builder and is wound with cotton -covered wire. The THE convenient radio outlets pictured on IMPROVEMENTS and refinements are adjustable primary coil is also space -wound this page will be appreciated by fans possible in all manufactured products, with enameled wire. who are anxious to improve the appearance including such simple items as battery -cable Manufacturer: Aero Products, Inc., Chi- of their installations. One outlet is equipped plugs as well as more complicated radio cago, Ill. with tip jacks for the aerial and ground parts. Although the usual cable connector connections and the other is provided with Sturdy New 110 -volt Switches a seven -wire jack and for Electric Receivers plug for the battery cable. Both outlets WITCHES of improved design have re- the market for are made of lacquered l../ cently been placed on brass and are the connection with A.C. -operated re- use in sane size as standard Electrically, these switches are ceivers. 110 -volt power out- identical with those previously available, but design has been changed lets. their mechanical With the battery - them better suited for front -panel to render wire outlet the jack -is They are of the standard 110 - mounting. on the frame be operated with knobs mounted volt type, and may is free for other radio apparatus. and the plug of the type used for connection with Their electrical rating is 3 amperes at 250 The outlets shown in this illus- the battery cable. The tration are volts. similar in finish to plug is made in two the wall plates used for lighting considerable difference in con- fixtures, There is a parts and may be and enable a room to switches which are used be wired attractively for radio. struction between taken apart for con- in battery sets and those which must be The tip jacks shown above are venience in soldering intended for concealed lead -in used for A.C. receivers. In battery sets the seven wires of the and ground connections. The -pole switch may be used, as the cable -plug receptacle any single battery cable to its below makes potential in the filament circuit is never more cono,ient the operation of terminals. Wires are a receiver from greater than six volts. On the other hand, either batteries to the or separate power unit, which the switch is connected in soldered jack in A.C. receivers for connection to the may be conveniently located for circuit, and the only switches set operation in several positions. a 110 -volt batteries. approved for this purpose are snap switches It is not necessary having a heavy spring which makes or to elaborate exten- breaks the circuit rapidly. Because of the sively on the ways in high voltage in the circuit this type of con- which these outlets struction is necessary in order to prevent between the poles of the switch. may be used, as they arcing convenient Of necessity snap switches are quick in are very action and, for this reason, the usual radio for a number of pur- knobs have not been used for their opera- poses. Of course, the way in which they tion. Most of the 110 -volt switches which have been available are of the toggle type, may be employed in and this has disappointed many set con- the individual instal- structors who have attempted to balance lation depends largely the arrangement of apparatus on their front on the arrangement of panel. the radio appa- The switches illustrated on this page are ratus. A radio experimenter might mount is quite satisfactory for the purpose for of the usual toggle type, but there have them in the with or on the top of a work- which it is intended, a device of improved been added to theist ingenious mechanical table to enable him to quickly connect bat- design which possesses several new features devices which permit operation by either teries when testing receivers. They are just has been recently developed and placed on a knob or plunger or in connection with a as valuable to the radio listener who may the market; it is illustrated in the drawings rheostat knob. In the case of the rheostat wish to wire his house so that the set may on the following page. combination, as the knob of the unit is be moved from one room to another quickly In electrical design, the cable connector turned to the `off" position the switch turns and easily; and for many other purposes under discussion does not differ greatly which will readily occur to user. the set off, and vice versa. The drawing the Such front the usual product of this type. The wiring is especially desirable during new shows the switch turned on, and dotted cable consists of seven wires which construction of residences and apartments. are of lines indicate the "off" position. In the different colors to permit identification; a knob-operated switch a ball- and -socket con- Manufacturer: l'axley Manufacturing Company, Chicago, Illinois. seven -contact plug is soldered to the wires nection joins the shaft with the switch at one end of the cable and this plug fits into and, in the central switch, a knee joint a receptacle which is mounted on. the base- couples the plunger with the contact arm. board or panel of the receiver. The con- Manufacturer: The Hart and Hegentan tact prongs of the plug are split so that Mfg. Co., Hartford, Caul. they make good contacts in their respective The combination of rheostat and sockets in the receptacle unit. Also, a lug switch shown at the right differs and notch have been placed in the plug and from the usual one in that the the receptacle, respectively, to insure that switch is a heavy -duty one. built to make and break circuits carry- the plug must always be inserted in the ing full house -lighting voltages. correct position. and therefore suitable for use in An interesting feature of the cable con- the power line fredinn the Unit. nector is that it is available with either of two mounting receptacles, one of which is designed for baseboard mounting and the 4=+ other for panel mounting; the construction The power switch shown of the two is shown in the drawings. Both above is co, trolled from the types are made of molded Bakelite, and the panel of a set by its knob: which is of conventional ap- The switch ,drown in the color of the wire to which each soldering pearance, but whose action, center differs only in be- lug connects is engraved on the back of the however, is to flip the sturdy ing operated by a shove or receptacle. The baseboard -type receptacle toggle which controls the in- pull of the knob, not a may be put from the lighting mains. tarn, unit is fitted with a base and
www.americanradiohistory.com 436 Radio News for November, 1928
It should he noted that the 180° meridian New Zealand is found coincident with 1.30 corresponds to the international date line. on the white scale, which indicates fore- CONTACT PLUG In going across this line from east longi- noon, and since we have already passed the tude to west longitude, a day is lost; in the 180° meridian, the time indicated is that other direction, a day is gained. That is, of the next day or 1.45 a.m., March 3. a place just east of this date line is one day later than is a place just west of this line. For an example of the use of the chart: BASEBOARD MOUNTING it is desired to.know the time in Alaska, in Map Makes Handy Record RECEPTACLE India, in Japan, and in New Zealand when of Continental Reception it is 9.15 a.m., March 2, in Washington, D. C. ACONVENIENT departure, from the Washington, D. C., is in the eastern -time usual wall -size map heretofore avail- zone of the United States and takes the able to the radio fan for logging purposes, time of the 75th meridian west. Setting is to bé found in a new copyrighted radio CABLE 9 white of the Mexico PANEL MOUNTING the on the half of the inner circle chart United States, Canada, RECEPTACLE so that it coincides with 75° west longitude, and the West Indies. It is niounted on a we are ready to read off the time in the substantial sheet of heavy drawing -board :In attractively- designed battery cable and re- other countries. Following the outer circle and measures only 18 x 12 inches; so that it ceptacles of two types designed for use in until the longitude; of Alaska is reached, it may be laid on the table or held in the lap. connecting its plug to a receiver. will be found the 4 on the white half of the This map is furnished with 100 colored inner circle coincides with this line, which markers to record stations heard; and near mounted in a vertical position. A hole 1/ indicates that it is 4.15 a.m., March 2. In the names of each "city the calls of the vari- inches in diameter is required to receive the the same way India is found half -way ous broadcast stations located there are panel -type receptacle unit; . the unit is between 7 and 8 on the black half of the printed in such an arrangement that a sepa- mounted on the rear of the panel and the inner circle, which indicates 7.30+.15 or rate marker may be used for each station plug is inserted in the hole. The design of 7.45 p.m., March 2, as the corresponding without undue crowding. receptacle units is such there is both that time for India. Likewise, the time indi- Manufacturer: Radio Map Company, easy access to the lugs with a soldering Los cated for Japan is 11.15 p. m., March 2. Angeles, Calif. iron, and the lugs have been tinned and slotted to facilitate the connection of wires. The plug unit also of the cable connector is of molded bakelite, and is in three sec- DEPARTMENT OF COMMERCE Miscellaneous Publication No. 64 tions; the plug proper, an insulating sepa- BUREAU OF STANDARDS rator, and a cap which protects the sol- GEORGE IL BURGESS, DúeM , .. ttte dered connections. The connections of the P.:« te..bt. plug are insulated carefully with bakelite partitions, so that a short- circuit of the wires is practically impossible, and a soft - rubber coupling prevents, any abnormal STANDARD TIME CONVERSION CHART strain on the wires. Also, if an open cir- FÚF cuit should occur, the plug unit may be dis- PY assembled and a new battery cable soldered . wESTcEAST in place. Manufacturer: Herbert II. Frost, Inc., Chicago, Ill. A Handy Time -Conversion Chart s ; ;e for th e Short -Wave DXer 4141M1'- 4 THE United States Department of Com- J merce recently has developed an inter- national time chart which will prove to be a very useful article for radio listeners, par - ticularly those who are interested in long - distance, short -wave reception. The chart is being printed by the Government and may be obtained at a cost of ten cents (coin, not stamps) by writing to the Super- intendent of Documents, Government Print- ing Office, Washington, D. C. It is made of heavy cardboard and is reproduced in the next column. Knowing the standard time and the longi- tude at any place on the earth, the corre- sponding standard time at any other place can be read directly from the chart. The inner circle is marked with the hours of the day, the white half for forenoon (a.m.) and black half for afternoon (p.m.); while the outer circle is marked off in degrees east and west of Greenwich. The inner circle may be revolved and by comparing the two scales, it will be seen that the time changes one hour for every 15 degrees change of longitude. To obtain the time at any place in rela- tion to the time at any other place, it is necessary only to set the time on the inner circle to the longitude of the place where (Directions for use on reverse side) the time is known and to read the time l indicated at the longitude of other place. Uncle Sam's handy calculator somewhat reduced. The circle of hours is pivoted in the center.
www.americanradiohistory.com Radio News for November, 1928 437
PUTTING T11E AERIAL IN SI1AFE FOR WINTER
Fig. B. Only weight counts in this -. Lary men should replace frayed halyards Fig.. position. Fig. C. One piece of wire for aerial and lead -in they break. It's a good deal easier before then. may be fastened as shown here and in Fig. A. chief trouble with the latter is that its NO'I'WITI- ISTA\DING the number effectiveness is limited by its elasticity while Be sure to do a thorough of indoor aerials and loops now job of soldering, the counterweight will allow the halyards to however, and one that will not used with ultra- sensitive radio eventually re- contract or stretch as much as needed with- allow the joint to corrode. ceivers there are many more out- out disturbing the tension of the aerial. door aerials, good, bad and indifferent. Al- Either one or the other idea is practically Avoid letting the lead -in hang over a flat most anything will do in fair weather, so necessary to overcome the tendency of the roof or enter the room just above a window long as it hangs fairly steady and keeps halyard to snap during extreme high winds, stool or ledge. (The diagrams in Fig. 3 dry; but winter weather, with its gales, wet and dry weather and similar disturb- illustrate why) ; this, of course, if the wire snow, sleet and ice often wrecks even the ing influences. is bare. With insulated wire the chances best aerial systems and renders the receiver for leaks are considerably less unless the useless until the wires can be put back in ONE PIECE OR TWO insulation becomes broken. order. Consequently, it behooves the radio While it is always preferable to have the No matter what the lead -in may be or owner to put up a good aerial and keep it aerial and lead-in wire in one piece to do how it entérs the room, provide aun insu- in order so that wild winter lator that will tip up through weather will not ruin it in the the wall and arrange a "drip - PULLEY first gale. To do this and to INSULATOR IQ bend" at the entrance. With a insure good reception throughout tipped -up insulator worst SPIRAL SPRING O the stormy periods, the following _mtnvevkvtN --sad driving storm cannot blow up hints should be followed and under and INSULATOR SNOW into the room; where- every 6H ALYARD COVERS as effort made to see that LEAD-IN one that tips down may lead INSULATOR TUBE insulators are inserted properly LEAD -IN to a stream of water eventually and halyards are strong, and TIPPED UP AT ANGLE running over the wall or floor. HALYARD r
RAIN DRIP At (1) and (2) we have optional The diagrams at (5) show three stages methods for a safe anchorage of the of the manufacture of a serviceable aerial: see Fig. B above. The wrong storm -guard for the lightning arrestor, tray to bring the lead -in down is shown which must be kept dry. The trick at (3): obvious, why didn't we think shown at (CO makes it possible to of it before.' The connection at (4) lubricate the aerial halyards con- will avoid lots of tranble. veniently. Prevention is always CUT cheaper than repairs.
that all connections are clean and 'l'he drip -bend in the lead also eliminate leaks and losses. tends to allow all accumulated First of all, do not secure the water on the lead to drop to outer end of the aerial to a tree d OIL the bottom of the loop and be if it can be helped. Trees natur- SOAKE blown off. This arrangement is ally bend and lash in high wind RAG shown in Fig. 4. and. unless some efficient com- B pensating device is inserted, the STORM GUARD FOR THE LIGHTNING ARRESTER SHORTS IN THE ARRESTOR aerial is sure to break. Of Watch your lightning arrestor; course, a big tree can he usu with away with splices, there are offsetting rea- it can cause much trouble -shooting because more or less success; but it is wise to have sons why a splice may be the lesser of two of a short between the contacts inside. This a stayed mast if possible. If a tree must evils. In winter a bare lead -in ruins every is especially true of arrestors with an open be used, take up the backlash and the chance of becoming imbedded in the snow back or other way by which rain or melt- shrinkage with either a spiral spring in the or sleet deposited on a window -sill or in ing snow can creep inside. If you hear a halyard, between the pulley and the in- a crevice, and thus short -circuiting the sig- click -click- click -during the height of a sulator, or a counterweight at the bottom nals to the ground. It happens many, many rain, but no such sound during dry weather, of the halyard. Either is good but the times that, when signals have died out dur- you can make up your mind the lightning writer prefers the counterweight; this can ing a snowstorm, it is later found that the arrestor is at fault. Even a sealed one be composed of any old junk metal slightly lead-in has been grounded in some such can short with water across the terminals. heavier than the weight of the aerial, so that way. Now, by having the lead -in of heavily A nice little hood is shown in Fig. 5 and it keeps the latter taut, as shown in Fig. 1. insulated wire and soldered securely to the can he quickly made from heavy roofing Fig. 2 illustrates the spring method; the aerial, such grounding is made impossible. (Continued on page 490)
www.americanradiohistory.com Radio News for November, 1928 Electrodynamic Speakers Become Popular How This Reproducer Differs Electrically and Mechanically From Other Horns and Cones, and the Necessary (14164 Conditions of its Operation 4*(0 By Fred H. Canfield
N who has made the slightest Telephone Laboratories (see RADIO NEWS attempt to follow radio develop- for April, 1928). Electrodynamic speaker ments during the past year is aware units were used for these transmissions, and of one outstanding trend which is listeners on the New Jersey shore of the the cause of considerable discussion at the Hudson River were able to hear clearly a present moment; namely, the greatly in- voice which was projected from a giant creased popularity of the electrodynamic horn installed atop a New fork office build- speaker. Less than one year ago a major- ing, three miles away. Of course, such per- ity of the broadcast listeners in the United formance cannot be expected from the usual States had never heard the term electro- speaker, but the experiment shows what may dynamic used in connection with a piece of be accomplished with specially-built electro- radio apparatus, whereas today it is on the dynamic units. Also, it may be pointed out tip of every radio fan's tongue. Further that such a feat has never been approached evidence of the sudden change which has with electromagnetic speakers of the type taken place in the loud- speaker field may usually used for radio reproduction. be gained from the fact that last year at this time only three manufacturers were NOT A NEW INVENTION making electrodynamic reproducers, and to- The electrodynamic speaker is not a new clay they are being sold by two- thirds invention, although the suddenness with (thirty -two) of the larger manufacturers of which great numbers of these speakers have receivers and by twenty -one speaker manu- appeared on the market has caused many facturers. persons to consider it as such. The fact is After giving the above statistics it is that the electrodynamic principle has been Fig. C. hardly necessary to explain that the electro- known and thoroughly appreciated by engi- This picture shows an electrodynamic speaker dynamic loud speaker is a superior repro- neers for a number of years, and at least cabinet of usual design. The grille. backed ducer of radio music. It may be said that one speaker of the type has been on the with a light cloth, conceals the opening for is the cone, and thé cabinet itself serves as a box- this loud speaker capable of. reproducing market since the early clays of broadcasting. type baffle. The rear of the cabinet is open, a radio program with less distortion than Also, it has been known that these speakers but covered with a wire mesh. any other type available at the present time. were capable of providing better results Also, these speakers are able to handle great than the usual design of "electromagnetic" use of a better speaker than those available. volume without overloading and without dis- speakers. They have not been used gener- Before continuing further with this ar- tortion. Those who are inclined tobe skep- ally because their construction is neces- ticle, the meaning of the tical of these claims are referred to ac- sarily moré elaborate and complicated than terni electrody- namic, when applied to loud speaker, will counts of the sound- transmission demonstra- other types, and because the quality of a be explained. In this connection it should tions conducted in New York City a few reproduction obtainable from the average be understood first that the word refers to months ago under the auspices of the Bell set in previous years did not warrant the the electrical principle upon which the speaker operates, and not to the construc- tion. From this it may be seen that any of the popular types of speakers, such as the cones, horns, stretched- diaphragms, etc., may be electrodynamic or permanent -mag- netic in principle; the only difference be- tween the two being in the loud- speaker unit. It so happens that a large majority of the electrodynamic speakers on the market are of the free -edge cone type, because this is considered the most practical design for these speakers.
WHAT THE DIFFERENCE IS The chief difference between the perma- nent- magnet and electrodynamic speaker units is in. the source of magnetic force. As the name indicates, the first type em- ploys a permanent magnet to produce the necessary lines of magnetic force; but in the case of the electrodynamic speaker, an electromagnet is used for the same purpose. Electromagnets have many advantages over permanent magnets, but they require a source of direct current for their operation. These magnets consist of coils of many turns of wire wound over cores of soft iron. With magnets of this type it is possible Fig. B to produce a field of great strength, such Two electrodynamic horn speakers are shown above; that to the left is a small as is required for the reproduction of cabinet -size exponential horn which has been designed for home use. The strong radio signals. speaker at the right is a large double exponential horn intended for use in the- The second difference between the two aters. in connection with the presentation of talking moving- pictures. It is five types of speaker units is in the method of by six feet in cross -section at the opening. producing vibrations of the diaphragm. In
www.americanradiohistory.com Radio News for November, 192Y 439 the permanent-magnet unit the modulated the small moving coil offers almost a pure Electrodynamic speaker units are made current from the radio receiver flows resistance load to the tube. These three also for exponential horns. 'l'he electrical through coils wound over the magnet, and factors, combined, stake it possible for the construction of these units is identical with a diaphragm is located so that it is sepa- speaker to provide great volume without that of the cone type, but the mechanical rated a fraction of an inch from the pole distortion, and allow the unit to provide construction is changed somewhat. The pieces of the magnet. The modulated cur- uniform reproduction on all frequencies. In frame for the cone and the cone itself are rent causes changes in the magnetic force addition, the driving unit itself does not eliminated, and the moving coil is attached and these cause the diaphragm to vibrate. have a definite resonance frequency. to a diaphragm. The picture, Fig. B, shows On the other hand, in the electrodynamic Another interesting feature of the elec- a large double exponential horn with two speaker a moving coil is freely suspended trodynamic speaker is that it will not electrodynamic units attached. This horn in the field of the electromagnet, and this weaken with use or ages; for there are no has a bell five by six feet in cross section, coil is fastened directly to a free -edge cone. permanent magnets to become weak as they and was designed for use in theaters in The modulated current from the receiver lose their magnetism. connection with talking moving pictures. i lowever, electrodynamic units for use with APPLICATIONS OF THE UNIT AMOIS smaller horn speakers are available. Early. in this article it was stated that A smaller speaker of this type, designed IRON CASE FRAME electrodynamic units may he em- for use in a console is also illus- SPRING FELT speaker cabinet, MOVING COIL NSULATION IRON ployed for the operation of any standard trated. CORE type of loud speaker, but that the free -edge THREE TYPES OF SPEAKERS cone speaker is now being used almost ex- clusively in connection with these units. Thus far in this article the various ad- The mechanical construction of a speaker vantages of electrodynamic speakers have. of this type is shown in Fig. 6, and a pic- been considered. However, there are many ture of the unit is given in Fig. A. interesting things regarding the operation of In these illustrations it will be seen that these speakers which must be explained. The MAGNETIC PATH the electrodynamic unit is much larger and first is supplying the current for the field ro ricco EICIT,Nc heavier than the permanent- magnet type. winding, and the following paragraphs will CURRENT SUPPLY TO RADIO OUTPUT TRANSFORMER The field winding consists of thousands of describe the various systems which may be MOUNTING HOLE turns of wire wound over a solid -iron core; used. this coil is housed in a heavy cast -iron case The electrodynamic speakers on. the mar- viz: Fig. 6 at least four inches long and four inches ket are of three general types, those which require a high- potential supply for The mechanical construction of an electro- in diameter. The frame for the cone is field winding, which low - dynamic speaker unit for a free -edge cone is attached to one end of this case, at the end the those require a illustrated in this cut -away drawing. The paper of which there is an opening for the moving potential supply, and those which obtain cone, to which the moving coil is attached, is coil. The paper cone is non -rigidly attached direct current for the field winding front non- rigidly supported in position by a spring an alternating- current supply. 'l'he latter at the apex and a strip of chamois at the is a opening. X -Y EFFECTIVE SIZE OF BAFFLE type of speaker merely plugged into 110 -volt A.C. light socket and a transformer passes through this coil, causing it to move WOODEN BAFFLE' and rectifier, built-in as part of the speak- in its field with each pulsation; and as the er, convert the A.C. into a low -voltage free -edge cone is fastened directly to the U.C. of the value required for the opera- UNIT coil, it vibrates and sets up the sound ELECTRODYNAMIC tion of the instrument. (See Fig. 3.) The waves we hear as voice or music. Yf first two types of speakers require an ex- MOUNTING HOLE ternal source of direct current. ADVANTAGES OF TILE DYNAMIC Speakers requiring a high -voltage sup- The outstanding electrical advantage of BRASS ply mar- be operated with D.C. developed the electrocl-nt speaker unit over other BRACKET by a standard "B" power unit, and the designs is found in the fact that the forces field winding may be employed as an A.F. SUPPORTING on coil are dependent only upon choke coil in the filter circuit at the same the moving BLOCK the current in that coil. The magnetic field time, thus improving the operating char- of the speaker is of great strength and WOODEN acteristics of the power unit. There are the coil in the field has no effect upon the BASEBOAR several different ways of connecting the reproduction. Also, there is no iron arma- field winding in the power -supply- circuit. ture to saturate. These facts result in Practically all of the speakers having complete freedom from distorting harmon- high -potential field windings require ap- ics introduced by the speaker itself. Fig. 4 proximately 50 milliamperes at 110 volts. The mechanical construction of- the elec- This drawing slows the method usually em- 'l'he selection of this value of current for trodynamic speaker unit results in addi- ployed in attaching an electrodynamic free - edge -cone speaker unit to a baffle of the flat tional advantages. From the drawings it type. The baffle board should be approxi- will be noticed that the motion of the mov- mately three feet square, and the frame of the ing coil is parallel to the pole pieces instead speaker should be securely fastened with Tvood screws to the baffle at the opening. of between them; as a result, the danger of hitting the pole pieces is eliminated. Sec- to the iron frame with a strip of chamois ondly, the usual driving rod, which is apt at the large end; at the apex a flexible to bend and vibrate, has been eliminated by spring holds it in position. Therefore, it attaching the moving coil directly to the may be seen that the cone is perfectly free cone diaphragms; in this way another cause to vibrate. The moving coil is attached to of distortion has been eliminated. Thirdly, the apex of the cone, and this coil fits over the iron core of the magnet. Connection is made to the moving coil with flexible wires, IRON CORE IRON CASE MOVING COIL CONE as shown. 'l'tvo methods are provided for mounting the usual electrodynamic cone. A bracket
.w_..-.- is fastened to the case for mounting the Ililli1111i 11 unit on a baseboard; the input transformer of the speaker is usually mounted on this sauce bracket. Also, holes are drilled in the Fig. A cone frame for fastening the baffle board .4u A.C.-operated electrodynamic rigidly in place. In addition, it will be speaker unit TO FIELD EXCITING/. TI O RADIO O UTPI of the free- edge -cone type is slow', above. CURRENT SUPPLY TRANSFORMER noticed that the front of the frame is cov- 711e instrument mounted on the left side of ered with the base is the input transformer, and the Fig 5 a felt pad in order to insure an air-tight connection between the frame and parts at the right of the base are the step - Th's schematic diagram clearly illustrates the down power transformer and the dry-electro- electrical design of an electrodynamic speaker. the baffle. lytic rectifier.
www.americanradiohistory.com 440 Radio News for November, 1928 the field supply is very fortunate, as 110 volts corresponds to the usual drop in volt- age across a choke coil in a "B" power unit, and the amount of current required by the average five- or six -tube receiver with a power tube in the last stage is about 50 milliamperes. Therefore, the field winding of the speaker may be substituted for one of the choke coils and no other adjustments are necessary. However, it is always wise to insert a milliammeter in series with the circuit to make sure that the speaker is receiving approximately the correct value of current. In receivers which employ more than six tubes, and sets which have a push-pull power stage, the plate current is frequently greater than the current required by the loud- speaker field winding. When this is the case, the method described above can- not be used without danger of burning out the field coil. However, there is a very simple solution to the problem; the filter circuit of the power unit is not disturbed and the field winding of the loud speaker is connected after the two choke coils in series with the positive wire. The plate Fig. i current for the push -pull power tubes is This diagram shows a combination "B" socket -power unit and last -stage A.F. then taken from the positive wire at a point amplifier, with the field winding of an electrodynamic speaker connected in place between the second choke coil and the field of one of the usual filter choke coils. When this arrangement is used the winding of the loud speaker. The advan- speaker receives field current, and the field winding acts also as a choke coil. tage of this circuit is that the plate current of the power tubes does not pass through nection. In either case this transformer the output transformer from the high -voltage the field winding of the loud speaker, and must be used, and the regular output trans- supply by connecting a large by -pass con- also the plate current supplied to the low - former or output filter in the receiver dis- denser in each of the two wires from the potential tubes of the receiver receives connected. primary of the transformer to the imped- additional filtering. When it is desired to use an electro- ance unit. These condensers are not essen- dynamic speaker in connection with a push - tial, but when the wires from the set to the COUPLING SPEAKER AND TUBE pull amplifier, another problem presents speaker are exposed, they serve as a pro- The second thing to consider in connec- itself, as the output transformer supplied tection against accidental contact with the tion with operating electrodynamic speakers with the speaker is not of the push -pull high voltage. is the method of connecting the moving coil type. The most satisfactory solution to Fig. 1 shows the complete circuit of an to the plate circuit of the last audio-ampli- this problem is to connect a center -tapped electrodynamic speaker connected with a lier tube. It should be explained that a output impedance unit in shunt with the standard full -wave "B" power unit and a step-down output transformer must be primary winding of the transformer, and power amplifier using a single tube in the used, and the impedance of the secondary to connect the two outside terminals of output circuit. Ti and V'1 are the usual winding of this transformer must be the impedance to the plates of the two povi'er transformer and the full -wave gas- matched to the impedance of the moving tubes. Then, the high -voltage supply for eous rectifier tube, with Cl and C2 buffer coil. The output transformer for these the push -pull tubes is connected to the condensers having a capacity of 0.1 -mf. L1 speakers is usually built into the speaker, center -tap terminal of the output imped- is a standard single filter choke; the field Ind is sometimes supplied for external con- ance. If desired, it is possible to insulate coil of the speaker (L2) replaces the sec- ond filter choke. The condensers, C3, C4 and C5, are the usual filter condensers, and CG and C7 are 1 -mf. by -pass conden- sers. In the amplifier circuit, T2 is a standard A.F. transformer, VI is the power tube and T3 is the output transformer, which is supplied with the loud speaker. The output transformer, it will be noticed, is connected to L3, the moving coil of the loud speaker.
OBTAINING PROPER FIELD CURRENT In arranging a circuit in this manner, it is important to make sure that the field winding of the speaker receives the proper current, and if the current in the circuit is insufficient, it will be necessary to change the characteristics of the voltage- dividing resistor, R1. For example, the instructions supplied with the speaker may state that a field current of from 40 to 70 milliamperes is required, and a milliammeter connected in series with the field winding may show that the current passing in the circuit is only 35 milliamperes. Under these condi- tions the speaker will not operate at maxi- mum efficiency, and it will be necessary to Fig. 2 use a voltage -dividing resistor of a lower When the total plate current of a socket -power unit exceeds a certain value the total resistance. It is possible to correct circuit shown in Fig. 1 cannot be used for the operation of an electrodynamic this condition by connecting a resistor in speaker without danger of burning out the field winding. The above circuit pro- shunt with the voltage divider or by re- vides a satisfactory solution to the problem, as the plate current for the power designing the resistor, as described in an tube is tapped before it reaches the field winding. article entitled "Applying Ohm's Law to
www.americanradiohistory.com Radio News for November, 1928 4.41
force each other if the proper precautions practical viewpoint, the box baffle is much are not taken, and it is the baffle which more satisfactory and, if it is properly de- prevents such interference. Also, the size signed, no trouble should be experienced. á of the baffle determines the lowest frequency The size of the battery compartment of which the speaker will reproduce with full most radio cabinets is such that satisfactory e results are assured. However, if it is de- Baffles are of two general types: the flat sired to construct a 100 -cycle box-type baffle and the box baffle. 'l'he two are baffle, this should be approximately 16 T2 equally effective, but the box -shaped baffle inches square and 10 inches deep. may be much smaller for equivalent results. In constructing a baffle there are several 6 y~j The rule which applies in this case is that things which should always be remembered. ó the lowest note which the speaker will re- First, it should be made of heavy wood, so produce at full volume is - the one whose that it will not vibrate excessively on its quarter wavelength is less than the distance own frequency. Secondly, the frame of the to the back of the cone speaker should make an air-tight joint with speaker from the front The socket- operated electrodynamic which is cut for uses a dry -electrolytic rectifier R to convert around the edge of the baffle. Therefore, the baffle at the opening the stepped-dawn A.C. current into 6 -volt direct the baffle should be as large as conveniently the cone. Thirdly, no holes should be cut current for the field winding LI. This ar- possible, but considerable latitude is per- in the front of the baffle other than the rangement may he used by the constructor missible. opening made for the cone. Lastly, the en- with a speaker of the D.C. type, or a trickle charger may be employed. To determine the wavelength of a note tire construction should be as rigid as pos- it is necessary to divide the speed of sound sible. Radio Apparatus," which was published on in air by the note's frequency. To find When the speaker is located in the sanie tubes, great care page 1348 of RADIO NEWS for June, 1928. the wavelength of a 100 -cycle note, for in- cabinet as the receiving However, in a great majority of cases it stance, it is necessary to divide 1120 feet must be taken to prevent its vibrations will be found that the current passing in (the speed of sound in air) by 100 cycles, from causing the microphonic sounds which the circuit will satisfy the requirements of and the result is 11.2 feet. As it is the so often ruin reproduction. For this rea- the speaker. quarter wave which is the important figure, son, both the speaker and the receiver should by Fig. 2 shows the method of connecting it is next necessary to divide this figure be mounted on a sound -insulating material, the speaker to a "B" power unit used in 4, and this gives us 2.8 feet, or 33.6 inches such as soft rubber. Special brackets are connection with a large set employing a for the quarter wavelength of a 100 -cycle sold for mounting speakers on a soft rub- push -pull amplifier. In this case the total note. ber cushion, and rubber pads may be placed current consumed by the set is so heavy that Provided a baffle is flat, there is no limit under each corner of the sub -panel of the it would be apt to burn out the winding to its desirable size. Speakers have been set to insulate it mechanically from the of the speaker, and, therefore, the plate inserted in the wall of a room, which is speaker. As an additional precaution, the current for power tubes is tapped before practically the equivalent of a baffle of in- sockets used in the set should be of the it reaches the speaker's field winding, which finite extent, with excellent results. How- cushion type, and the tubes should be fit- is connected as part of the voltage divider. ever, under average conditions a 100-cycle ted with heavy ballast caps. In this circuit all the wiring and parts on baffle is entirely satisfactory, although bet- Very often, after unsuccessful attempts the left side of the "13 +JIax." wire is stand- ter results could be obtained if it were still to eliminate microphonic noises, it is found ard, but on the right side of the line several larger. A baffle of the flat type having a that poorly- constructed apparatus used in changes have been made. Part of the volt- 100 -cycle cut -off frequency will consist of the receiver is responsible. If it is sus- age divider must be removed from the cir- a board approximately 35 inches square pected that the tubes are not the cause cuit to compensate for the drop in poten- with a hole cut in the exact center for the of the trouble the next parts to examine are tial which takes place across the windings cone. the variable condensers. If condensers with unduly thin plates are used the vibrations of the loud speaker, and probably the re- BUILDING INTO A CABINET may sound like tube noises mainder of the voltage divider will have to In general, the box -type baffle is used set up in them he redesigned to permit a flow of current more frequently than the flat type because in the speaker. sufficient to operate the field winding of the it is more conservative in space require- speaker. For data on redesigning the volt- ments. As the effectiveness of a baffle is age divider the reader is again referred to determined by the shortest air-wave dis- the article in the June number of RADIO tance between the front and back of the NEWS. The circuit also shows the method cone, it may be seen that a box baffle is of connecting the output circuit of the push-. the approximate equivalent of a flat baffle pull amplifier with the moving coil of the of much larger size. Therefore, the lower speaker. L5 is a standard center -tapped compartments of radio console cabinets output impedance unit, and T3 is the out- often serve as very efficient baffles for elec- put transformer of the speaker. 'l'he con- trodynamic speakers, as indicated in Fig. i. densers C9 and C10 are not absolutely One objection to the box baffle, however, is necessary, but, if used, -should have a ca- its tendency to resonate or "boom." If pacity of 2 to 4 mf. - the box is shallow from front to back, With the low -potential electrodynamic though high and wide, this effect is not speakers, the field coil is operated usually noticeable. If the box is deep from front by a storage battery- connected to the wind- to back, while small in its other dimensions, ing, but it is also possible to employ A.C. the effect will probably be objectionable. operation, as shown in Fig. 3. ln this cir- To overcome this trouble, holes should be cuit T1 and R are a step -down transformer bored in the sides, top or bottom; or the and a full -wave dry -electrolytic rectifier, re- sides should be lined with felt, or other spectively, which deliver direct current at sound- absorbing material. In general, with 6 volts and / ampere. A standard trickle a box less than 18 inches square and deeper charger may be used to supply this current. than one foot from front to back, some precautions should be taken to prevent WHAT IS A BAFFLE? resonance. Any box, the back of which The baffle is the next subject for con- is not almost entirely open or which lacks sideration in connection with the operation some other outlet of equivalent size for of electrodynamic speakers. The baffle is the sound from the back surface of the cone, a board on which the speaker is mounted; will resonate badly unless a great deal of Fig. 7 itit is absolutely essential in order to obtain felt is used. A grille, covered with a light good reproduction from electrodynamic cloth, is usually the equivalent of an open- .4 convenient method of mounting an electro- dynamic speaker in a console cabinet is shown units of the free -edge cone type. In speak- ing for the purpose. here. The lower part of the cabinet is thus ers of this type two distinct sets of sound The remarks made above regarding the converted into a baffle box, and the speaker waves are set up, one from the front and tendency of box baffles to resonate should should be so mounted that it comes in the one from the rear of the cone. These sound exact center of its compartment. It should be not discourage the set builder from em- provided with rubber feet to avoid vibration of waves will alternately neutralize and rein- ploying this type of construction. From a the shelf on tchich the set rests.
www.americanradiohistory.com 442 Radio News for November, 1928
Some Facts About Transformers By C. Walter Palmer
1'lt:a \SFOn is a device for TURNS RATIO illustration, Fig. 2, there are three general transferring electrical energy from The entire purpose of a transformer is types of cores used for transformers. 'l'he one alternating- current circuit to to transfer energy from one circuit to an- first is the open -core type, which has the another, and for changing the vol- other, and, if desired, to change the voltage lowest efficiency of the three. The second tage from one value to another. The us- of the secondary to a different value from is the closed -core type, which is used ual transformer consists of two coils of that in the primary. The voltage across almost exclusively for small transformers. wire wound on an iron or soft steel "core." the secondary of a transformer is propor- The windings on this type of transformer The coil through which the current is tional to the ratio of the number of turns may be both on one arm of the core, as supplied to the transformer is called the in the primary to the number in the second- shown in Fig. 3; or the primary and second- "primary," and the coil from which the elec- ary. If we have a transformer operating on ary may be wound on opposite arms, as trical power is taken is called the "second- a 100 -volt supply and 500 turns of wire are in Fig. 4. The third type of transformer ary." The alternating current traveling used in the primary, a secondary contain- is the shell type, with a completely closed through the wire in the primary causes ing 100 turns would have approximately core. This type of transformer is usually the iron core to become magnetized. This 1/5 of the primary voltage, or 20 volts. used when large currents are involved. produces a varying magnetic field in the There are three general types of trans- Fig. 2 also shows an auto- transformer. core, and because of the movement of this formers. The first has equal primary and An auto- transformer contains a single field, a corresponding voltage and electrical secondary windings, and the secondary volt- winding, with a tap somewhere along it. current is produced in the secondary by age is the same as that impressed on the In the step -up type, the total winding is "electromagnetic induction." primary. The second type has a secondary used as the secondary and part of the sanie It is necessary to use alternating or smaller than the primary, and the second- winding (front one end to the tap) is fluctuating current in a transformer. ary voltage is lower than that of the prim- used for the primary. In a step -down A steady direct current in the primary ary; this is a "step- down" transformer. auto- transformer, the tap is placed in such winding would magnetize the core and The third type has a larger secondary than a position that the ratio of the total wind- thus produce a magnetic field, but this primary and the secondary voltage is higher ing to the section supplies the correct ratio field would be stationary and it is the than the primary; this is a "step -up" trans- of primary and secondary turns, for the re- movement of the field that induces the former. The exact value of the voltage in quired secondary voltage. The entire wind- current in the secondary coil. Alternating the secondary depends upon the turns ra- ing is used as the primary, while the tapped current is continually changing, rising to a tio, as explained. See Fig. 1. section becomes the secondary. In a step - certain value, then falling to zero, rising in 'l'here is a slight loss of power in a up auto- transformer, the tapped section is the opposite direction and reversing again. transformer, for'which there are a number the primary and the entire winding the Because of this continually varying action, of reasons. The windings present a certain secondary. the magnetic field is also varying, and the resistance to the current, and some of the WHY THE LAMINATIONS? form of the voltage induced in the second - power is lost in overcoming this resistance. ary winding corresponds to that of the volt- The core also presents a certain amount of In order to reduce the heat losses in tb. age in the primary. It is not absolutely heat loss, due to the currents which are cores of transformers, they are almost in- necessary to have a primary current set up in its laminations. The wire losses variably made of very thin sheets of iron, change its direction periodically, as alter- can be reduced by using heavy wire and each one insulated electrically from the nating- current does; it is only necessary the losses in the iron can be reduced by others. This arrangement prevents large in to have its value change continually. A using a closed type of core. induced currents from being set up the fluctuating direct current in the primary of core. In a closed -core transformer with a OF CORES a transformer will induce a fluctuating cur- THREE TYPES solid core, the core can be considered as a rent in the secondary. As you will notice in the accompanying single turn secondary which would have a
Transformer A is of the 1:1 type; primary and secondary hare an the primary. Transformer B is of the "step -down" type; trans- equal number of turns, and the secondary voltage is the same as former C. of the "step -up" variety. depending on the "turns- ratio.'
www.americanradiohistory.com Radio News for November, 1928 443
PRI.
SEC.
SEC. PRI Olt 411011. OPEN CORE CLOSED CORE SHELL -TYPE CORE AUTO- TRANSFORMER FIG. 2 Above are shown the four general types of transformers. In the type, the whole winding is the primary and the tapped portion the auto -transformer, if it is of the step -up kind, all of the single wind- secondary. In the shell -type transformer, both the primary and ing is the secondary «nd part of it the primary. If of the step -down secondary are wound on the center section of the core. very low voltage but high current- capacity radio signals from one stage to another. a high current drain. The last two wind- characteristic. Naturally, the current flow- ings are usually designed to supply 1 to 2 ing around the closed ring would cause a POWER TRANSFORMERS amperes, since they are used for one or two lot of heat and a corresponding loss of use- Power transformers are heavily con- power tubes. ful current. These currents are called structed with large cores and heavy wire, The second type of power transformer "eddy" currents. In transformers using since relatively large currents are passed supplies the high voltage required for the laminated cores, they are broken up into through them. Most commercial trans- plates of vacuum tubes in a radio set, and small sections in each lamination, and since formers are placed in metal boxes and a is used in "B" socket -power units. This the laminations are insulated, the heat losses number of models are sealed in wax or type of transformer has a secondary wind- are reduced considerably. other compounds, to "damp" core vibration. ing with a-large number of turns of rather An interesting fact about transformers thin wire, since only a small amount of is that when the secondary circuit is opened, current is required. These transformers very little current flows in the primary. are wound with either a single secondary 64 128 256 512 1024 2048 4096 This is due to the fact that the value of 32 winding for a single rectifying element, or the magnetic current set up in the core is BASS VIOL %vith a center -tapped secondary for the full - gradually increased when no current is TROMBONE wave type of rectifier. The difference be- - drawn from the secondary. This magnetic CELLO tween these two systems is that in the half is current reacts on the primary and produces CORNET wave type, only half of the A.C. cycle another voltage in the latter which is just 080E usefully employed. When the current is direction, it is opposite to the original current impressed FLUTE traveling in the opposite upon this winding. This additional voltage not used, but is merely stopped by the VIOLIN and increases in value until it stops all of the PIANO rectifier. This type of transformer current from the supply line, except just rectifier supplies a fluctuating direct tur- enough to produce a magnetic field suffi- FIG. 5 ret, and a very efficient filter system cient to maintain the opposite voltage. must be used to smooth it out into the a This chart shore the range of frequencies cow for the "B" supply. Therefore, a transformer connected to ere/ by the common musical -instruments. steady current required supply line and having its secondary open The other type of rectifier (full -wave) small amount of on both halves of the cycle, and will draw an exceedingly In very large power transformers, the operates produces a steadier current which requires current. windings and cores are exposed to a current in radio can less filtering or ironing out. The transformers employed of cold air or they are immersed in oil or be into two classes: those divided general water to keep them cool. However, in THE VOLTAGE VALUES filament current and plate volt- supplying transformers designed for ordinary radio power units are and those used in audio - Transformers for "B" age to the tubes, receiving work, this is not necessary, since voltages for frequency amplifiers for transferring the arranged to supply different the devices are small and excessive heating the different systems employed. The most can be avoided by their natural exposure to www.americanradiohistory.com 444 Radio News for November, 1928 Four commercial transformers sold for radio use. A, B and C are combination unit which furnishes "B" voltage as well as filament filament -lighting transformers, which step down the 110 -volt, 60 -cycle current. Transformers are also available, which supply both fibc- alternating house current to values between 1 and 15 volts. D is a ment and plate current, with one core. tion, or 450 volts maximum. This trans- step -up, push -pull, auto- transformer and deliver them to the following tube with an former is used with the filament type or output. The problems involved in each of increase in voltage. However, the compa r- gaseous-content type rectifying tubes to these types are approximately the same and ative voltage changes on the different sig- supply the plate current to the 171- and a general discussion of these problems will nals must all be the same, so that natural 112 -types, as well as to the other tubes in be worth while. reproduction will result. the set. The purpose of the transformer used as If the primary of the transformer is The other common type supplies current a coupling device between two vacuum too small (if it has too low an impedance), at about 500 volts and is of either the tubes in an amplifier is to receive the cur- the lower frequencies will pass through half- or full -wave type. This transformer is rent changes from the preceding tube and without affecting the secondary. The low Used with the filament type of rectifier impedance does not allow the current to tubes to supply plate current to the 210 and magnetize the core or transfer the energy 250 power tubes. The current required to the secondary, and the low frequencies from the secondaries of these transformers are by- passed through the primary wind- depends upon the type of rectifier tube em- ing. It has been found that the primary ployed, and the amount of current neces- impedance should be two or three times sary for the receiver. It usually varies be- the tube output resistance in order to fully tween 60 and 150 milliamperes. This is a amplify the lower notes. rather small current, since a milliampere is one- thousandth of an ampere. OBTAINING CORRECT IMPEDANCE Besicles these two general types of trans- In order to obtain the correct primary formers and the variations of each type, impedance, it is better to use a large core there are several combination transformers rather than increase the number of turns in now being sold. These transformers have the primary. If a small core is used, the both large and small secondary windings, primary 'must contain a great number of so that the filament and plate supply can turns and naturally this also means an un- be obtained from a single unit. A number usually large secondary coil in order to of these transformers are wound with high - get the step -up ratio between the two coils. voltage, full -wave windings and either 'l'he use of a very large secondary will also center -tapped or untapped windings to sup- have a bad effect, since it has a tendency ply filament current. to increase the capacity between the turns AUDIO -FREQUENCY TRANSFORMERS of wire in the secondary. This value is known as the distributed capacity, and The problem of designing good audio - when it is increased, the higher frequencies frequency amplifying transformers is very are by- passed by it and are not properly different from that of designing power amplified. transformers. In the latter, currents at It is generally considered that, the only one frequency have to be considered, larger the core of a transformer, the more and the windings and core can easily be uniformly it will tend to amplify both the arranged to give the greatest efficiency at Above: A, standard step -up transformer ampli- high and low frequencies. The core must this figure. However, in amplifying trans- fier circuit. B, push -pull hook-up. C, auto -. be made special transformer arrangement. of magnetic material with formers, a very wide band of frequencies a high magnetic value, or permeability. must be covered with uniform efficiency, so Below: An amplifying transformer (left) com- pared in size with a "B" supply transformer. '/'here are two currents flowing through that the signals and music will not be dis- an audio- frequency transformer. The torted. first is the alternating current which con- By referring to the chart of frequencies stitutes the signal and the other -is the covered by common musical instruments direct current of the "B" supply. In a that will be found on the preceding page, transformer with a small core, these two it will be seen that currents together may an average broadcast be sufficient to sat- transmission covers a urate the iron. In band between 30 and other words, the core 5,000 cycles. An ideal is not large enough to transformer should handle all of the mag- transfer currents of netic field produced any frequency in this by the primary wind- band equally well. ing. This condition Transformers f o r may cause the pro- audio-frequency am- duction of harmonics plifying circuits can of frequencies which be divided into four (Continued on. page types; the ordinary 486) www.americanradiohistory.com Radio News for November, 1928 445 SHOULD BE GOOD NEED ANY ASSISTANTS? COUNT 'EM AND SEE 'SERVICE MAN (after W I F E (awakening CITY BOARDER listening to local in- her husband) : "T h e (watching F a r ni e r / terference in re- early morning radio Timothy milk the , ceiver): "I am afraid, setting -up exercises cow): "Oh, yes, that madam, that it is your are on! You left the set has four tubes, location which is to radio turned on when hasn't it blame. The set is you went to bed! working all right." TIRED DX FAN OWNER (justly indignant) : "I'll have (after a liard night): "Please be quiet. I'm RUNNING DOWN HIS BATTERIES you know, young man, I have as good a doing my daily dozin' . " -A. H. Rodiek. location as anyone in this town. I pay $80 JUNIOR FAN (enter- a month rent here !"-S. O. Taylor. ing hastily from out- HIS DX WAS NB (NEAR -BY) doors at night) : "O FIRST RADIO FAN: "What sort of a set papa! The cat's tubes has Joe got ?" are lit! I saw his LOOKED LIKE PHONES SECOND Dirro: "Well, you don't need a panel lights !"-Philip It was so cold that radio log with his receiver. All you need is Tracy. day that the traffic a splinter. " -A. H. Rodiek. EDISON'S GREAT RIVAL cop stationed at the 1 / school corner had to - CASEY: "My static eliminator was invented + page is devoted to humor of purely by an Irishman!" wear muffs over his THISradio interest; and our readers are in- ears. But he was vited to contribute pointed and snappy JONES: "What was his name ?" jokes -no long -winded compositions-of an CASEY: "Pat Pending." slightly surprised original nature. For each one of this na- when one little tad ture accepted and printed, $1.00 will be -Billy R. Meredith. paid. Each must deal with radio in some stopped to look at him of its phases. Actual humorous occur- carefully and then rences, preferably in broadcasting, will be NO KEYHOLE WORK preferred. Address Broadcastatics, care RADIO SALES ?IAN: came up close and inquired, confidentially: RADIO NEWS, 230 Fifth Avenue, New "Good morning, "Say, mister, what station are you get- York City. madam. With this fine ting now ? " -Mollie Zacharias. six -tube radio you can PUSHING THE SCOTCH TOO FAR listen in on what all What is the difference between a storage the world is doing." THE LOST ART battery and a native of Aberdeen? COLORED PROSPECT: The storage battery can be overcharged! "No, sah, ah believes A (Provi- local The Saveloy (house organ of the in minding mall own dence) station ended -From British Broadcasting Co.) business, sah r' a morning talk for -Wilfred Anderson (Bermuda). housewives with the promise of a free SHADOWED TO HIS DOOM CHEAP ENOUGH cook -book to those FAN No. 1: "Say, why are you so inter- A resident of Mel- listeners who would ested in getting a tele- bourne recently had a call at certain chain vision set working ?" radio set installed,' stores. One young housewife who had FAN No. 2: "I want and when his bill was purchased baked beans, salmon, condensed to see what Old Man presented this aston milk, canned tomatoes, etc., inquired as an Static looks like, so fishing item was at the afterthought for the cook -book offered by I'll know him. Then .end of the account: radio. "Lady," said the clerk, thoughtfully, 1'11 get him and get "For hanging aerial "you don't want a cook -book; just a can - him good, too!" aid myself-22 shill- opener."- Theodore .4. Monahan. -George Jess. ings."-Arthur Russell (.Australia). RADIO RHYMES No. 13 THERE'S JUST ONE THING- I WONDER wHV EACH THeN O'ER 'mu 'DROWSY NO DOUBT THE SCiENT15tS I'D LIKE TO KNOW TUNEFUL 51-12 AIN FEELWGS CREEP. WILL CLAIM THAT'S QUEER TO ME IN LIKE ANESTHETIC , DRUGS AND LULL YOU TO PRO- 1-I -105E ETHER WAVES RADIO - THE HRAIN I. -. FOUNDEST SLEEP. MUST BE To BLAME! www.americanradiohistory.com Radio News for November, 1928 How to Construct the "Pre- Selector" A Receiver Accessory Which Provides Extreme Selectivity Without Loss of Sensitivity or Additional Controls By S. Gordon Taylor TIIERE has always been a strong de- SOLVING THE PROBLEM of amplification in the accessory unit to mand for an accessory that could be make up for the losses which In spite of these faults, there are thou- are bound to connected to any standard radio re- result from any method might be sands upon thousands of these two classes that used ceiver to improve its selectivity. In to increase selectivity; this meant of accessories in use today. Such being the that at general, such devices have fallen into one of least one tube would have to be included case, it seemed well worth while to devote two classes. 'l'he first is the well -known in the unit. Furthermore, either the re- some attention to the development of a unit wavetrap, by means of which a single inter- ceiver or the unit would have to be untuned that would really the maximum fering station may be trapped out, either provide if we were to avoid adding tuning controls. practical degree of selectivity but which partially or completely; the second class in- - Finally, the tube circuit or circuits in the cludes what amounts to an additional stage (1) Would not decrease volume or signal unit could not be tuned to the same fre- of radio -frequency amplification built as a strength; quency as those in the receiver because the separate unit and connected ahead of the (2) Would not receiver. complicate tuning or Both of these accessories have the dis- operation; advantage of adding one or more tuning (3) Would not tend controls and both, therefore, tend to com- to make the receiver plicate the operation of a receiver. They unstable, and, have also individual faults. The wavetrap, for instance, is not always capable of en- TAYLOR tirely cutting out even the single interfering PRE -SELECTOR station for which it is adjusted and, fur- Fig. C thermore, it frequently reduces the intensity The "PreSelector" has IT volume of the desired signals. The added an attractive appearance: its controls supersede en- stage of R.F. amplification almost always tirely those of the receiv- tends to make the receiver unstable by in- ing set, which may be creasing undesirable feedback. To prevent placed elsewhere. oscillation in such a combination it is usually necessary to turn back the volume control, or the sensitivity control of the receiver, (4) Would be ap- with the result that the over -all sensitivity plicable to the gen- of the combination is often actually less eral run of receivers Gl Ca Cz than that of the receiver alone. Most radio in use today. --(5 experimenters have tried devices of both It was decided that these conditions could addition of a resonant tube circuit would hinds and have recollections of these facts. not be met without providing some degree upset the stability of the receiver. In the face of all these requirements, it became obvious that the only possible method of securing the desired results would be through the use of a heterodyne system. An experimental unit which included a "first detector" and oscillator was, there- fore, built up. With this arrangement, the tuning controls of the receiver proper could be set at one wavelength and left there at all times, and the new unit would act as a frequency -converter to alter the frequency of any incoming signal to the frequency (wavelength) to which the receiver was tuned. The wavelength selected for the receiver was one ,just above the broadcast band, 560 meters to be exact. This scheme worked out admirably as far as selectivity is concerned. It also simplified operation, because all tuning is accomplished with the two controls of the unit instead-of the three controls of the receiver proper. The com- bined outfit is also stable -even more stable than the receiver alone, because the receiver is now permanently tuned to such a high wavelength. IMPROVING THE DESIGN The only drawback found in this experi- mental unit was that it did not provide quite as ereat over-all sensitivity as with the re- ceiver alone. Further experimental work was carried on. therefore, to overcome this objection. First, by increasing the antenna Fig. B coupling in the unit, greater input -signal The aerial coupling of LI is automatically varied with the wavelength by the movement of CI, voltage was obtained and this has the same which tunes the first- detector input. L2 comprises the oscillator coils and coupler. Ranto NEWS Free Blueprint Article. No. 68. www.americanradiohistory.com Radio News for November, 1928 447 With receivers which employ a regenera- tive detector without R.F. amplification R3 C5 preceding, the Pre -Selector changes the in- C6 ,C2 regenerative cir- SW2 P L2 V2 put characteristics of the cuit sufficiently to prevent proper regenera- tion. In some superheterodyne receivers the ) double- heterodyne action will result in har- monics and "birdie" whistles. This is not true of all superheterodynes ; because in some cases the Pre -Selector has been found C4 just as satisfactory with receivers of this type as with tuned R.F. outfits. ivxw- HOW THE PRE -SELECTOR FUNCTIONS R2 L3 is between SW I The Pre -Selector connected the aerial and the "Aer." binding post of the receiver with which it is to be used, and DL the tuning controls of the receiver arc ad- TC7 justed to resonance at any wavelength above the broadcast band; usually around 560 0 meters, for this is as high as most standard GND AER. A- A+ B- B+ OUTPUT A- receivers will tune. The Pre -Selector may 45V. RECEIVER be connected to the batteries employed by the receiver or may have its own set of bat- teries, whichever is more convenient; more Fig. 1 will be said about this later. The schematic diagram of the "Pre -Selector," above, shows it to be actually the frequency- The dial the Pre- Selector is the changing end of a superheterodyne, for whose amplifier any tuned -R.F. set may be used. The left of first detector is regenerative. wavelength or tuning adjustment; it con- trols the variable condenser CI which times effect as would increased amplification. volume at the unit rather than at the re- the secondary of the antenna coupler L1 in 'l'hen regeneration was added to the circuit ceiver; a special high -resistance potenti- the input circuit of the first tube VI. This of the "first detector." These two changes ometer was therefore included in the an- coupler includes a center -tapped primary both increased the pickup, and increased tenna circuit. Thus, not only the tuning winding mounted on a movable carriage amplification was obtained. Thus the last and all filaments, but also the volume, were which, in turn, is geared to the rear end of requirement was more than satisfied. entirely controlled without going near the the shaft of condenser Cl by means of the Next, a good deal of time and effort was receiver proper. cans- and -pin arrangement, supplied with spent in further refining the device. It was Finally, the unit was considered deserving the coupler. Thus, the primary coil is found, for instance, that when the input &- of a name and it was informally christened moved in and out of the secondary coil to chit of the unit was tuned to certain wave- the "Pre- Selector." vary the coupling according to the wave- lengths the unit did not function as eli- The Pre -Selector has been tried out with length to which the circuit is tuned. ciently as at others. Also, under certain -a great many receivers, both commercial In series with this secondary winding of conditions, the tuning of one dial tended to and home built. Of all which were tried, the antenna coupler is the small pick -up alter the setting of the other. It was de- the only sets with which it did not perform coil which constitutes part P of the oscil- cided, therefore, that variable coupling be- in the usual manner were certain super - lator coil, L2. By means of this pick -up tween the antenna and the unit is necessary heterodynes and some receivers which em- coil part of the oscillator energy is im- and the coupling coil was redesigned to pro- ploy only a regenerative detector and audio pressed upon the detector grid circuit along vide automatically variable coupling. This amplification. In every case where the re- with the incoming signal from the broad- arrangement consists of gearing the primary ceiver employed one or more stages of tuned cast station that has been tuned in. of the antenna coil to the shaft of the R.F. amplification, the results were ex- The detector combines these two fre- tuning condenser; so that the antenna cellent. quencies to form a third, which is equal to coupling increases and decreases as the con-. denser is tuned for high and low waves, re- spectively. Careful design of the oscillator pick -up coil also helped to improve the results. The next refinement consists of a switch which is incorporated in the unit for the purpose of turning a receiver's filaments off and on, together with the filaments of the two tubes in the unit itself. For this pur- pose a combination rheostat and switch is included in the unit. The former controls the filaments of the two tubes and, when it is turned off, opens the switch which con- trols the receiver filaments. REMOTE- CONTROL APPLICATION A very important possibility, and one which had not been thought of in the be- ginning, was that of employing this unit as a remote- control device. Inasmuch as the input frequency is changed during its prog- ress through the unit, there should be little chance for feedback from the output to the input (aerial) lead. Therefore, there is no good reason why the unit cannot he placed some distance from the receiver. Experi- ment proved this theory to be correct and no difficulty was encountered in operating a L3 in 5 receiver the next room, approximately 20 feet away from the aerial lead and the Fig. A new unit. This experiment brought up an- This view from above shows how direct are the leads employed in wiring the Pre -Selector. AU other requirement -- wires arc run above the wooden baseboard. Two methods of connecting to batteries appear in -that of controlling the Figs. 2 and 3. www.americanradiohistory.com 448 Radio News for November, 1928 the difference between the two frequencies present in the grid circuit. By tuning the oscillator circuit this third frequency may 30 TURNS 47 TURNS he wade equal to that, say 535 TAPPED kilocycles 15?" TURN. Z8 D.S.C. (560 meters), to which the receiver proper #30 D.S.C. PRIMARY 2 "- DIAMETER 116= DIAMETER. has been tuned preciously and the signal 12 -TURN# 36 D.S.0 from the broadcast station will be amplified PICK -UP in the receiver and heard in the loud 14.-DIAMETER speaker. From the foregoing explanation it is ap- ri parent that an installation, which includes a timed -R.F. receiver and the Pre -Selector, really amounts to a superheterodyne re- -Id- ceiver; in which the Pre -Selector functions N as the so- called "first detector" and os- cillator, while the R.F. amplifier of the re- ceiver proper serves as the intermediate IÌI amplifier of the combination. 114 TURNS SPACED FEATURES OF THE CIRCUIT %28 D.S.C. SECONDARY` 2 "- DIAMETER ) The tremendous selectivity afforded by 47 TURNS 4128 D.S.G. the Pre- Selector is due largely 2"- DIAMETER to the fre- 64r TURNS *36DSC. LI quency- changing process involved. In ad- TICKLER 11/2."-DIA. dition, the Pre- Selector combination pro- vides better selectivity than the average Fig. 4 superheterodyne receiver; because the R.F. Details of the coils; the primary of L1 is mounted on a slide, which is moved out amplifier of even a very broad -tuning broad- of the secondary by a cam on the tuning condenser Cl as the rotor plates rise. cast receiver is tuned much more sharply than are the coupling transformers ordi- narily employed in the intermediate stages the amplification it provides. Ordinarily ception, the knob is turned up to a point of a regular superheterodyne receiver. the regeneration control, C4, is left with just below that at which the detector goes Regeneration in the detector circuit of its knob set at zero. It is only in the case into oscillation. The regeneration is ob- the Pre- Selector is not required for the of reception from very distant stations that sake of selectivity, but is used solely for regeneration is required and, for such re- TO FRAME C4, OF CONDENSER R1- IIIIIIIIIIIIIIIIIII Illllllllllllllllr SW1 V2 + J' i- JIM PIPIT !I !lgtIIIIII ailíi.!IiI 1 IlPnnnnuq m n'lll... ii: I :,, . 1 1 =°ï' aÌÍÍÌÍIIII 11 ° r Illla : IIcM ' 1 r- Imïlüüiüiüilddlau nu 1 IIII I SOLDER TO l BRACKET L2 MOUNTED si ON FRAME OF I1 CONDENSER C2 A- OUTPUT B+ B- A+ A- SW2 AER. GND RECEIVER 45V Fig. 5 COIL LI MOUNTED ON FRAME Complete wiring layout of the "Pre- Selector;" the apparatus is OF CONDENSER Cl *lightly spread apart in the picture to show the connections. www.americanradiohistory.com Radio News for November, 1928 449 14' waveband. This a decided convenience, weak, distant 5/32 DRILL AND particularly when tuning for COUNTERSINK, 2 HOLES stations. CONSTRUCTION AND WIRING /g DRILL The diagrams and photographic repro- 6 HOLES ductions provide practically all the data re- quired for the construction of the Pre - Selector; the only point that needs be N touched upon is the mounting of the coils. Both LI and 12 are mounted directly on the frames of their respective tuning con- 3/g DRILL densers. L2 should be mounted in a vertical HOLES 5 1 5/32 DRILL position with the small pick -up coil at the 3 HOLES top. A tapped hole will be found in the rear of the frame of condenser C2, and a 6/32 screw passed through the hole in the brass mounting bracket of the coil and screwed into that in the condenser pro- vides a convenient and substantial means } for mounting. 3' 3' The curved brass bracket which comes with LI should be mounted on the frame of the coil by means of the two small screws provided. Its position should be that, when 2 the coil is mounted in the position shown in T-1 the top view (Fig. A), the slotted lug on the bracket should be toward the panel and pointing down. Next, mount this coupler 10' on the rear of condenser Cl by means of When in po- 542 DRILL, B HOLES 3/g DRILL the screw provided. proper sition, the notch in the lug of the mounting Fig. 6 bracket should be astride the rib on the Drilling details of the "Pre- Selector" panel and binding -post strip. back of the condenser frame. tamed through the use of a feed -back coil SUPPLY AND INSTALLATION in a fixed position inside of the mounted If it is used with a battery -operated re- the coupler, I.I. secondary of input No. 68 ceiver the same set of batteries may be used noted from the diagram,Fig. 1, RADIO MEWS large blue- It will be d set of for the Pre -Selector. Or, if the receiver that a switch, SW2, has been included in FREE prints and a list of parts PRINT uses a `B" socket -power unit, that may also the ground side of the antenna circuit. This BLUE used in the construction ARTICLE' be used to provide the plate current for the required, not for its effect on se- Selector" switch is of the "Pre- Pre-Selector. If the receiver employs A.C. lectivity but rather to permit the smooth shown here will be sent tubes, it will then be necessary to provide a and consistent control of regeneration. to any applicant. Write to postpaid set of three standard dry cells to supply the Where a very large antenna is employed, Department; write your the Blueprint Pre -Selector's filament; one set of batteries with the full primary winding in the circuit, name and address and "No. 68" leg- will provide approximately 200 hours of the absorption effect is so great as to make ibly on a sheet of paper separate service. The rheostat (R1) included regeneration ineffective. In such a case the from letters to other departments. actual in the filament circuit of the Pre -Selector switch is set so that only half of the wind- We regret to inform our correspond- is of resistance sufficiently high to permit ing is in the antenna circuit, thus reducing ents, especially abroad, that U. S. these tubes to be operated safely from a the absorption effect to overcome this diffi- postal regulations do not permit send- six -volt source. With the supply voltage the culty. ing blueprints with magazines; nor rheostat should be turned on half -way to The by-pass condenser C7 has been in- can we undertake to accept blanket operating voltage for these cluded in the ground circuit of the Pre - "all blueprints." provide proper requests for is volts the Selector, simply as a safety measure, to pre- tubes; if the supply source 4/ vent any possibility of short- circuiting the rheostat should be turned on three -quarters. "A" current in cases where the same de- When dry cells are used the three -quarters cells are new; vice is used to provide the filament current added to the tuned oscillator circuit to position is correct while the be as the for both the Pre -Selector and the receiver. cause the two tuning -condenser dials to but the rheostat must advanced The only other circuit feature not covered read alike. When it has been adjusted so cell voltage drops. cases as, instance, where the is that which employs the small adjustable that the two tuning controls read alike for In some for unit is built permanently condenser, C3. The purpose of this con- a given wavelength, their readings will re- "B" socket -power denser is to permit enough capacity to be main alike throughout almost the entire (Continued on page 483) -BATTERY HOOK -UP WHERE BOTH RECEIVER AND - BATTERY HOOK -UP WHERE PRE - SELECTOR IS EQUIPPED WITH SEPARATE BATTERIES PRE - SELECTOR USE SAME 'A' AND 'B" BATTERIES- - TO - (NEG.) TERMINAL 'B BATTERY OF RECEIVER 'A' BATTERY. 0 0 0 -B- 0 0 0 45%, - BATT TO RECEIVER BATT BATT. 'AER' TERMINAL TO RECEIVER 'GRD' TERMINAL TO 'A- TERMINAL # OF RECEIVER 'B'- TERMINAL MuJSI BE LEFT NOTE UNCONNECTED. ; THIS CONNECTION IS MADE FOR USE ONLY WHEN RECEIVER A- AER. A+ B+ B+ B+ B- ONO PRE - SELECTOR FILAMENTS ARE TO BE TURNED OFF PRE - SELECTOR 45V. 90V. 135. AND ON BY SWITCH SI OF PRE - OR /BO V. SELECTOR. IN MAKING THESE CONNECTIONS REMOVE NORMAL NORMAL CONNECTIONS TO CONNECTION BETWEEN RECEIVER RECEIVER TERMINALS. -A -' AND BATTERY 2. Here the "B -" connection is left unused, to avoid a short across Fig. 3. Even though separate batteries are used, the connection shown the filaments of tic 199 -type tubes. makes remote control of the receiver easy. www.americanradiohistory.com 450 Radio News for November, 1928 Magneto - Striction An Interesting Field for the Radio Experimenter; to Build a Magneto -Striction Oscillator By M. J. Cztttler RADIO NEWS LaGoratories ccERROMAGNETIC" substances (such as iron, cobalt, nickel and al- loys into which those metals enter in considerable proportion) possess "magneto- strictioe" properties; which means that they undergo slight mechanical altera- tions of shape, and some of their physical properties change when they are subjected to the influence of a magnetic field. This action of the magnetic field on such sub stances is manifested in a series of effects discovered at different epochs and known under various names. The oldest among these is the "Joule ef- fect," discovered by Joule about 1847; this is the variation of the length of a ferro- magnetic rod exposed to a magnetic field. Let us consider an iron rod freely suspended 11r. Outlier is shown here testing the magneto- striction oscillator described inside of a long solenoid; an electric cur- in the accompany article. rent of constant intensity flowing through a solenoid creates a magnetic field which is practically uniform within the solenoid over original value, and will then continue to con- ferromagnetic rod located in a magnetic n great of its length; provided that the part tract until a saturation point is reached. field is accompanied by a variation in its ratio between the length and diameter is Any further increase of the field strength magnetization or its permeability. As we sufficiently high. This is illustrated in Fig. will have no more effect on the length of have seen in the Joule effect, various sub- 1. The field strength within the coil is pro- the rod. stances behave differently under the same portional to the intensity of the current, and The behavior of other ferromagnetic sub- conditions; but there is a relation, for each the variation of the field may be governed stances under the same conditions will .be metal, between its Villari effect and its through the regulation of the magnetizing different. Nickel, for instance, continuously Joule effect. An investigator (Nagaoka) current. decreases in its length; while cast cobalt, in who followed Joule, has confirmed his sup- contrast to iron, first contracts and then ex- position that a magnetic field AN ALTERNATING ACTION has an in- pands, reaches its original length and con- fluence on the volume of a ferromagnetic Let us now examine what happens to the tinues to elongate until saturation occurs. substance. iron rod if the field inside the solenoid is The relation between the strength of the Another very interesting phenomenon varied from zero upwards. First, an elon- magnetic field and the variation of the which belongs to the same group is the gation will take place. This will continue length is shown clearly in Fig. 2. (Both "Wiedemann effect" and its two inverse ef- until the field's strength reaches a certain figures are taken from an article on mag- fects. The Wiedemann effect is the twist- value, after which any further increase of neto -striction by S. R. Williams, published ing of a rod under the influence of a combi- the field will cause a contraction; the rod in the Bulletin of the National Research nation of two fields, one longitudinal and then becomes shorter, will again reach its Council, August, 1922. one circular. Suppose a magnetic rod is Other ferromagnetic substances may re- clamped at one end inside of a long sole- spond differently, but one thing is common noid; then a current passing through the to them all; they vary in length (whether solenoid produces a uniform longitudinal positively or negatively) with a rising field field inside of it. If, at the same time, strength, and reach a point where satura- another current flows through the rod, a tion occurs, after which a further increase circular field will be created around it. If of the field has practically no effect on their one of these currents is kept constant while length. the other is varied, or if both currents are An important remark is to be made here; varied, a rotation of the further end will be the Joule effect is dependent on the direc- observed. tion of the field. As the extent of the varia- The two corresponding inverse effects are: tions in the length of such rods is extremely first, a circular field is created when a rod minute, their measurement is a matter of which is located in a magnetic field is sud- great difficulty; the utmost care must be taken to avoid temperature variations and changes in other physical conditions, which may conceal the real values. Various ingenious arrangements have been used for such measurements; Fig. 3 gives a schematic layout of the method used by Professor Williams. The method of opera- tion is self-explanatory; the expansion or contraction of the rod under test is con- verted into angular rotation of the mirror by means of the lever. CORRESPONDING PHENOMENA FIG.1 To the Joule effect corresponds another The field within a solenoid magnetic is prac, phenomenon which is its opposite; These Orally uniform in distribution, as illustrated the "Vil- curves show how various metals change herewith. lari effect." The forcible lengthening in length under the influence of a magnetic of a field. www.americanradiohistory.com Radio Newts tor Novelnbe,. 1928 431 reader will find there a most complete bibliographical notice on this subject. CLAMP DESIGN OF THE OSCILLATOR 'l'he Joule effect has been very ingeniously applied by G. W. Pierce, director of the Cruft Laboratory at Harvard University, in SOLENOID a series of electrical devices for which a British patent has been recently granted. BRASS HOLDERS Among them, the single -tube magneto- SAMPLE UNDER striction oscillator deserves the most atten- TEST tion. (By the way, Professor Pierce is the inventor of the single -tube piezo-electric oscillator, a device which is of almost uni- versal use in broadcast stations, and of growing popularity among radio amateurs.) ROTATING SHAFT The fundamental circuit of the nickel TILTING MIRROR oscillator is shown in heavy lines in Fig. 5. KNIFE The dotted part of the drawing represents BRONZE RIBBON an amplifying stage, which is not essential for the operation of the oscillator. As may be seen from the sketch, the essential ele- rod, LEVER ment of the circuit is the ferromagnetic which is clamped at its middle point. The FRAME FBALANCING two coils Ll and L2, of equal inductance to the FIG.3 WEIGHT value, are connected, respectively, grid and plate circuit, and surround the rod 11 OW the change in length of a rod is observed. .45 the rod varies, it unbalances the lever, which without touching it. The variable condenser tightens or loosens the bronze ribbon. This C is connected to the grid and plate, and causes the shaft to turn the mirror, the move- completes an oscillatory circuit. Disregard- How the twisting of a rod under the influence ment of which is readily observed. of two magnetic fields is observed. One field is ing the presence of the rod, the circuit is created by the solenoid; the other by the current lenly twisted. A sensitive galvanometer identical to the Hartley oscillator, with the passing through the rod and indicated by the connected across the rod will indicate a flow exception that the coils are connected in the ammeter A. of current. Second, a longitudinal field is opposite direction. temperature fluctuations, the generated fre- created along a rod to which a sudden twist When the oscillatory circuit is tuned by quency is of remarkable constancy, and may is given, if an electric current is passing the variable condenser to a frequency which be used as a standard for calibrating pur- it. through A galvanometer connected to is close to the natural longitudinal frequency poses. the terminals of the solenoid will show the of the rod, a sudden rise in the plate cur- This type of oscillator will cover a rela- existence of a current. rent is observed in the milliammeter, and tively wide range of frequencies, from a The schematic of the method used layout the rod begins to vibrate. If the frequency few hundred cycles up to 300,000 cycles per to measure the Wiedemann effect is shown falls within the audible range, this vibration second and, as a standardizing device, fills in Fig. 4. Here, again, the rod is clamped of the rod may be heard very distinctly. in a gap between the range of the vacuum - at one end inside solenoid.- To the the free The frequency of the current generated by tube- driven tuning fork and that of the end is attached a protruding brass extension the tube is now the same as the natural fre- piezo- electric oscillator. On the other hand, which carries a small mirror. mag- If the quency of the rod. it may find a very wide field of application, netizing current of the solenoid is constant, in connection with synchronizing devices a rotation of the mirror will be observed A CONSTANT -FREQUENCY CIRCUIT used in television and transmission of pic- when the electric current passing selected, through If all elements are properly the tures over wireS or radio. the rod is varied. capacity of the tuning condenser may be There are many other phenomena belong- considerably varied without having any dis- THEORY OF OPERATION ing to the same group. Those of our readers turbing effect on the frequency of the tube, We will now try to explain briefly the who are more interested in this subject, we which is now controlled exclusively. by the operation of a magneto-striction oscillator. refer to the excellent and very clearly- vibrating rod. Similarly, it is not influenced Let us consider a ferromagnetic rod written article on magneto -striction by Pro- by either a variation of the filament current clamped at its middle point and surrounded fessor Williams, in the May, 1927, issue of or any reasonable change in the plate volt- by a coil through which an alternating cur- the Journal of the Optical Society of Amer- ages. If the ferromagnetic substance used rent is passing (we assume that the coil ica. Besides the general theoretical consid- is of such a nature that the natural fre- does not touch the rod). During a complete erations and methods of measurement, the quency of the rod is not affected by small cycle, the field strength inside of the coil varies from zero to maximum, from maxi- mum to zero, again to maximum (in opposite direction) and conies back to zero again. As the Joule effect is independent of the direction of the field, the variation of the length of the rod during the same period will pass through zero to maximum, zero, maximum, and zero again. In other words. to each cycle of the magnetizing current will correspond two cycles of the variation of the length of the rod; that is to say, the rod will vibrate with a frequency which is twice that of the magnetizing current. Suppose now that, simultaneously with the alternating current, a direct current flows through the coil. If the intensity of this di- rect current is higher than the amplitude of the alternating current, the resulting cur- rent will vary, but will never become zero. During one cycle, it will pass from minimum to maximum and come back to minimum once; and so will the magnetizing field. Ac- The circuit of the magneto- striction oscillator. The dotted portion indicates an additional amplify- cordingly, the length of the rod will vary in ing stage. F.M.R.. ferromagnetic rod; Cl, 1 -m(.; C, tuning condenser; Ll, L2, inductors; .4, the same way and, to each cycle of the alter- plate milliammeter; P, telephone receivers; K.S., knife switch; L3, 800 -turn honeycomb coil; L. IV.3f.. long -wave wavemcter. nating current, will correspond one cycle www.americanradiohistory.com 452 Radio News for November, 1928 the driving force of a weight or a spring, as in a dock; the energy of the pendulum after each complete cycle is restored to its origi- nal value by a release of corresponding ALTERNATING CURRENT A amount from the driving mechanism.) Simultaneously with the vibration of the rod, an oscillatory current, the frequency of A which is controlled by the rod, will flow i Fig. 6.4 illustrates the through the plate coil. x Tonle effect. For each Tuning one of the coils with a condenser complete cycle of the mag- Z-s netising current, the rod or both together (Hartley circuit) does not 11Ju within the magnetic field alter the fundamental principle of I opera- I u I of that current vibrates TWICE: that is, the fre- tion in this type of oscillator. o? quency of vibration of the rod is equal to twice SELECTION OF APPARATUS LL the frequency of the al A1I lA tcrnating current. If, as The above simplified theory gives us some in Fig. 6B, a direct cur- ideas about the elements to be used and rent is added to the alter- I 1 nating one, the rod will their constants and characteristics. ® vibrate at the frequency (1) The tube should be of the "high -mu" I 1 of the alternating current. 1 1 type, although satisfactory results may be - obtained with other types. /NI /III Alik (2) The substance of the rod is of the highest importance. It must have sharply- ONE CYCLE: ONE CYCLE ¡ pronounced magneto -strictive properties N M--- and, preferably, should not reverse the di- I-PURE A.C. FIG.6 QA II'RESULTING CURRENT rection of the change in its length during a single half -cycle of the magnetizing force. A Comparing with Fig. 2, the characteristics of the variation of the length of the rod. inductance between the two coils, and the of iron, cast cobalt and nickel, we find that The rod will vibrate now with the same fre- other as a result of the Joule effect and its the latter is the most suitable material of quency as the alternating current. Those opposite. The resulting emf. will cause the the three. two cases are illustrated in Figs. 6A and plate current to fluctuate with the natural Some of the nickel alloys, such as invar 6B. frequency of the rod. Ordinarily, the vibra- (30% nickel, 63.8% iron and 0.2% carbon), We will now return to the oscillator. To tions of the rod produced by a shock, or any nichrome (60% nickel, 12% chromium, 26% simplify the case, we will assume that there other momentary disturbance in the internal iron), or monel metal (66% nickel, 33.5% is no tuning condenser across the coils. balancing forces, would not continue in- copper and 0.5% iron), have been found to (Such an oscillator may operate provided definitely; as they are damped by the losses require excessively long rods. For the pur- the amplifying power of the tube is high of energy and would die out very quickly. pose of obtaining low frequencies, the ends enough. A single tube may be replaced by But here the conditions are different; if the of a shorter rod may be loaded with weights. an amplifier having several resistance - elements are properly selected and the circuit Also, we may use a tube made of a mag- coupled stages.) One coil is then inserted is connected in the right way, the decrease neto- strictive substance which is filled out into the grid circuit of the first stage, while in the amplitude after each oscillation may with a metal having a low sound -velocity; the other is connected to the plate of the be compensated by the current in the tube, for instance, lead (4,025 feet per second, as last stage. (One form of Professor Pierce's and a sustained longitudinal oscillation will compared to 16,315 for nickel). patent application.) take place in the rod. The rod will be driven (3) As to the shape and the inductance Suppose, now, that the rod is at rest and by the tube. (Something similar we find in values of the coils, more complicated and, that the plate current has a constant in- the oscillation of a pendulum maintained by to a certain extent, contradictory, consid- tensity, which is determined by the char- erations enter. The plate coil has to be de- acteristics of the tube and the applied volt- signed in accordance with the direct -current ages. The rod becomes magnetized under component of the peak current and the mag- the influence of the field created by the second coil. This magnetization is not uni- form, as the field strength along the rod is not uniform. Should there happen a sudden variation of the plate current (due, for instance, to an exterior cause) a tendency in the rod to expand or contract, due to the Joule effect, will be caused instantly. The situation is somewhat similar to the case in which a shock is given to the rod in the line of its length. The particles of the metal are thrown out of balance, and longitudinal oscillation will take place in the rod under the action of the two forces of elasticity and inertia. FREQUENCY OF THE ROD The fundamental frequency of the rod may be found by dividing the velocity of sound in the substance of which the rod is composed, by twice its length. During the longitudinal oscillation of the rod, variation in its magnetization will occur (V Mardi ef- fect). An oscillatory electromotive force will be created in each of the two coils; those electromotive forces will have the same fundamental frequency although, as a gen- eral rule, they will differ in their other ele- ments. A variation of the plate circuit then will The complete magneto- striction oscillator as constructed in the RADIO News Labora- cause the appearance of two electromotive tory. The "loatd speaker" resting on the vibrating rod is merely a rolled sheet of dorces in the grid coil; one due to the mutual writing paper. Note the simplicity of the whole oscillator. www.americanradiohistory.com Radio News for November, 1928 453 neto-strictive characteristics of the sub- special parts were constructed; they used less its operation could easily be detected, the cir- stance employed in the rod. A field so parts under hand, from which it was ex- either by the milliammeter in plate pitch. The strong as to cause saturation (with regard pected to obtain some results. cuit, or by sound of a very high by the use to the Joule effect) must be avoided. On The monel -fetal rod is -inch in di- acoustical effect can be amplified / with a pin glued to the other hand, an equal variation of the ameter and 7 -13/64 inches long. The tube of a small paper cone results were plate current will cause a larger Joule effect is of the standard 201A type, and has 90 its apex, as shown. Still better a drinking cup playing in the rod when a coil of larger inductance volts on the plate. The method of clamping obtained with paper of a loud speaker. value is used. A similar consideration may the rod between two knife -edges is clearly the role shown in Fig. 7. Three sets of different be applied to the grid coil. A 13,000-CYCLE NOTE The dimensions of those coils lie within coils were used, with no very appreciable relatively large limits and the most desirable difference in the results. The coils shown The dotted part of Fig. 5 shows the values may be obtained only through a com- in the pictures are wound on hard -rubber method used to measure the frequency of plicated mathematical analysis, connected tubing, / -inch in diameter and 2 -3/16 current. A 1,000 -turn honeycomb coil was with a considerable amount of experimental inches long. There are 26 layers of approxi- inserted in the plate circuit of the amplify- work. mately 60 turns each of No. 30 S.C.C. copper ing stage, and the frequency was measured wire. Each coil has an inductance of ap- by a General Radio No. 224 wavemeter. CONSTANTS OF A SET -UP proximately 25 millihenries. The secondaries This was in close accordance with the com- The photographs reproduced here show a of an intermediate- frequency iron -core puted natural frequency of the rod. By magneto- strictive oscillator built in the transformer formed another set which was Newton's formula, we calculate the velocity RADIO NEWS Laboratories. The designers tried. of sound in monel metal to be approxi- had no particular frequency in mind and no This oscillator is not powerful; nevcrthe- mately 4,760 meters per second. Having divided this value by 0.366 (which is twice the length of the rod, expressed in meters), we found the same number, 13,000. The phones in series with the honeycomb coil were short -circuited during the fre- quency measurements. 'rhe tremendous penetrating power of such a high note is surprising. Although the intensity of the sound in the neighbor- hood of the rod was not very great, it could be heard distinctly in the adjoining rooms, separated by wood and glass partitions. Some of the members of the editorial staff, without suspecting the source, had com- plained of being annoyed by a hissing, "drill- ing" sound. The construction of such an oscillator in- volves no great difficulties nor expense. The essential elements of success in experiment- ing are thoughtfulness, care and a knowl- edge of what is going on; and those of our readers who will build such an apparatus will certainly discover a large field for in- illn stration above sbous just how the ferro- magnetic rod of mancl or other suitable metal is teresting experimental work, and perhaps will be suitable; the rhunped is place, without damping its vibrations. Any similar arrangement valuable practical applications. base may be of wood half an inch thick, or more. Ways of Sensitizing the R. F. Amplifier with Stability THE popular tuned- radio -frequency cir- The potentiometer -stabilized set today is making the grid positive. It draws too even intro - cuit of late has been improved by the no longer efficient with the closely- packed heavily on the plate supply. It widespread introduction of two methods of wavelengths. It tunes too broadly, due to (Continued on page 4.82) stabilization: namely, plate- voltage control and grid suppression. In fact, these methods have come to replace in large measure the previous potentiometer stabilizer which fig- ured in early R.F. circuits, and, to a lesser extent, the neutralization method which played an important role a few years ago. Few radio enthusiasts, even at this late date, seem to appreciate the significance of plate- voltage control. They take it for granted that 90 volts is approximately the correct voltage, and let it go at that. Of course, 90 volts will give results in R.F. amplification, but so will 67% and 135, if necessary. The radio- frequency tubes may be operated at maximum efficiency if pro- vided with the proper plate voltage to meet existing conditions in the individual receiver. Thus the old -time potentiometer stabilizer, which serves to make the grid positive, may be dispensed with if the R.F. tubes have the precise plate voltage to keep them just a shade under oscillation. In the neutrodyne circuit the neutralizing condensers may he At A we have an "old -fashioned" 400 -ohm -pote ,tiometer arrangement. which regulates the action removed and the R.F. amplifier controlled of the tube by varying its grid bias ( "Eg" in ne characteristic curve). The circuit shown at B is a modification which varies the plate voltage ( "Ep ") and thereby produces the desired regula- by precise plate voltage, with a marked tion more satisfactorily. In this case the resis or El should have a range up to 500,000 ohms. gain in sensitivity. Condensers and chokes arc omitted for simplicity. www.americanradiohistory.com 454 Radio News for November, 1928 A Way to Mount a Home -Made methods of using the same batteries for both a re prepared; each with a tip plug on one Scanning Disc purposes. However, in a large percentage end and a connecting lug or spring clip on of the cases where a single set of batteries the other end. experimenting with television, who is to be used for more one FFANS than purpose, the are making their equipment, find it quite frequent reconnections are considered more difficult to mount the scanning disc on the of a nuisance than the saving is worth. shaft of the motor; particularly in view of Many systems for rapid change -over of the T' fact that the disc must run perfectly batteries from one set to another have been true in order to give good results. If the suggested and many of these are very sat- I disc is home -made, the job is much harder isfactory. In most cases, the instructions á1, All : TAPE than when a manufactured disc is used; call for batteries to be mounted perma- but, in either case, the bushing must be HOLE MUST BE DRILLED SO caË nently under the work -table or in some other THAT SCREW ON CLAMP ABOVE - quite large in order to prevent the disc from convenient location, and the binding posts of MAY FIT EASILY METAL wobbling. THE LITTLE SCREW WHICH CLAMP the batteries are connected to a terminal A satisfactory hushing for a television FITS IN THIS HOLE WILL INSURE strip mounted on the work -table. With this A GOOD CONNECTION WHEN disc he may made from an old radio dial system, any receiver may be connected easily SET IS IN USE as illustrated in Fig. 1. First the hole in with the binding posts on the terminal strip TO+0F'A 81NDING POSTS ON SET the center of the dial is drilled all the way and there is very little danger of short-cir- through and, if is necessary, it enlarged to cuiting the cells. However, the task of M1G. 3. The movement of the phone's auto- fit the shaft of the motor. Next, fromtwo fastening wires to the posts of the terminal matic- switch hook can be used to cut off the to loud speaker during conversation. four holes are drilled at equal distances strip requires considerable time, each time around the riot of the dial. The dial is now a set is connected. To placed in the exact center of the scanning A system which the writer has found very facilitate connecting the receiver to disc, the terminal and used as a template for drilling satisfactory for this purpose is illustrated strip, a strip of paper may be holes in the scanning disc, pasted in front of the which correspond in Fig. 2, below. It will be noticed that the tip jacks and the with those drilled in the rim of the dial. color of each wire of the battery cable may After this has been accomplished it is nec- be marked in front of the particular jack essary only to mount the dial on the scan - with which it connects, as indicated. When ing disc, with from two to four machine - connecting other apparatus to the batteries screws. the separate connecting wires are used for OLD RADIO DIAL the When selecting a dial for this purpose, it SET SCREW purpose. The connecting lug of each is important to make sure that it is made of wire may be fastened to any binding post, good bakelite. Many of the inexpensive MOTOR and the tip plug may be inserted in the dials are made of other compounds which SCREWS proper jack on the terminal strip. do not have sufficient mechanical strength. NUTS Only seven tip jacks are shown on the -Contributed bp Albert Baez, Jr., East terminal strip illustrated, but there is no Orange, N. J. DRILL HOLES WIDTH reason why a greater number of plugs could OF SCREWS not be used. For a complete work -table, METHOD OF ATTACHING the experimenter might include also jacks SCANNING SHAFT DISC Handy Current -Supply for MOTOR for the aerial, ground, loud speaker, and The Experimenter 110 -volt A.C., as well as lower A.C. volt- FIG. 1. Plain bakelite dials make strong bush- ages for filament supply. -Contributed by EXPERIMEXTERS who desire to build ings to attach a disc centrally to a motor shaft. E. L. Gibson, Atlanta, Ga. and test all kinds of radio apparatus, yet at all times have one receiver which may batteries are connected to a terminal strip be operated, are always faced with the ques- in the usual manner, but the terminal strip tion of power supply. Many have found it is equipped with tip plugs instead of the Telephone Automatically Cuts necessary to maintain two complete sets of usual binding posts. When this arrange- Off Radio Set batteries or power units, one for the house- ment is followed, a tip plug is fastened to hold music maker and the other for experi- each wire of the battery cable leading from IN radio -equipped homes the loud speaker ments; while others have tried various the set, and a number of connecting wires usually is considered a nuisance when trying to talk on the telephone. If loud signals are being received, it is necessary either to turn off the radio set or ask the /JACKS, person at the other end of the wire to re- peat almost everything he says. Both of A- A+ B- B+45 V. B+90 V. B+135 V. these things are annoying, but they may be eliminated easily with the simple device t% . 0 0 illustrated in Fig. 3. This device is a home- BLACK YELLOW GREEN BLUE MAROON RED i made switch which automatically discon- nects the radio receiver when the telephone TERMINAL STRIP receiver is removed front the hook. PLUG I,3, WIR The construction of the switch is illustra- LUG ted clearly in the drawing; it consists of NUT two one which is ?2?'2c»'tL2« www.americanradiohistory.com Radio News for November, 1928 45 ceiver is removed. Both contacts should compress the springs and reduce the dis- be carefully insulated from the telephone tance between the two diaphragms. This ADIOo NEWS has received from read - itself. makes it very much easier to join the R so many letters and ballots As suggested in the illustrations, the diaphragms, and after this has been done requesting more "Wrinkles" that it switch may be disconnected in the filament the nuts may be loosened as much as needed. has been decided to re- establish the circuit of the set, thus turning off the tubes It will be seen that, as the nuts are loosened, department. A year's subscription to when the telephone receiver is picked up. the springs will expand and the tension on RADIO NEWS will be given in compen- However, this system is not very satis- the diaphragm will increase. The use of the sation for each accepted item. If the factory unless the telephone is near the springs also greatly facilitates the adjust- author of the wrinkle is already o radio set; for long wires in the filament cir- ment of the receiver after it has been subscriber, his subscription will be ex- cuits tend to decrease the efficiency of the placed in operation. Contributed by J. A. tended one year or he may accept a set. But the switch will give equally good Johnson, Knapp, llrisconsin. one year's subscription to Science and results when connected in series with a Invention or Amazing Stories, both loud -speaker wire. -Contributed by Francis published by the Experimenter Pub- Piscitelli, .A':c York City. Plug -in Tips Facilitate lishing Co. Condenser Trials STRONG DURING experiments with new circuits, SPRING it is often necessary to change a fixed a receptacle. For this purpose a small Bake- ltttttttftttt 1111t11Mttf condenser frequently until the proper value lite panel 1 x2 x 3/16 inches is used and is found. In most cases, changing a fixed two tip jacks are mounted on it, at the condenser means disconnecting two soldered proper distance apart. Also, two extra SPEAKER joints and making two new soldered con- holes are drilled at the ends for mounting WOODEN UNITS nections. This operation requires a con- screws. For experiments, the receptacle is FRAME siderable amount of time, thus making it connected in the circuit and various sizes difficult to compare the results obtained with of plug-in condensers are inserted until the the two condensers. However, the problem proper value is found. -Contributed by would be simplified greatly if plug -in fixed Morris Dorsey, Atlanta, Ga. condensers were used; as with this system DRIVING it would be possible to make a change al- LINEN - ROD most instantly. DIAPHRAGM Fig. 5 shows how a standard, molded Home -Made Gauge Saves Time fixed condenser may be converted easily into ADJUSTING in Construction a plug -in condenser. The two terminal -NUT screws of the condenser should be removed WHEN you are drilling the front panel and two standard tip plugs may he screwed of a radio receiver, it is important to into the threaded holes of the condenser. know the exact size of each hole required before starting to drill: If the set builder l'i,.. 4. By taking up the springs, it is made The plugs which are on the market have casier to join the two diaphragms; and they mounting screws which will fit into the guesses at the size of the drill needed, the are easily balanced with the aid of the nuts threaded terminal holes of most of the hole is apt to be too large or too small. If at the corners. the hole is too large the mounting screws arc apt to loosen up after the set has been in Spring Mounting Adjusts a use for a short time; and, so far as small Linen Speaker Easily holes are concerned, it is always more trou- ble to enlarge them than it is to drill them DTHING the past year the linen -dia- to the correct size in the first place.. phragm speaker has become one of the The amateur who has only a few drills most popular -types in use. This speaker available will find the device shown in Fig. is rather bulky, in comparison with other (i a great aid when drilling a front panel. types, but it provides very uniform repro- A small piece of Bakelite or hard wood, duction over the entire frequency -range about 3 x î x 3/16 inches, is selected and in when properly adjusted, and is particularly this one hole is drilled with each drill in the satisfactory for low notes. There is another The various holes in the order of FIG. 5. of different values are tool box. be considered Condensers advantage which also must readily tested at any place in a circuit with their size should be drilled in straight lines, and in connection with these speakers; that this arrangement. about 1 inch apart. Next, the number on is, their design is such that they may be the shank of the drill should be marked in constructed at home. molded condensers but, if the thread of front of the corresponding hole for identi- Fans who have built linen- diaphragm the condenser is too large, the plug may be fication. speakers have found that satisfactory repro- soldered in place. When making a set, it will be convenient duction is obtained only when the proper After the condenser has been prepared to use the device described above to select Also, tension is applied to the diaphragms. as described above, it is necessary to make (Continued on page 489) for best results this tension must be very great; thus, as the quality is improved, the construction becomes increasingly difficult. This is because of the fact that in building 7 the speaker the diaphragms must first be I I distance, and then separated to the proper rI the centers of the diaphragms must be 3 I _ 5:6 ° brought together. 32 4 8' 3-52' T of the type 32 73 In a linen -diaphragm speaker I illustrated in Fig. 4, ninny- of the difficulties _ G=ai íi. i w \\ - experienced with the usual device of this _ type have been eliminated. In this speaker I 1- -I- - -1 1 the usual wooden frames for the diaphragms 1 are used, but the two frames are separated ;_A`A'/,á A,V3 by springs instead of wooden spacers. The __ -. be unusually strong, : t, -Ill; springs, which must Ir-,9 1,-JJ I I{ammor3" may be purchased at large hardware stores. g -'64,,1z - They are placed over bolts which join the --T: 4='` two frames. In building the speaker, when the dia- phragms are to be drawn together, the nuts on the bolts may be tightened in order to Fla. 6. A gauge prepared in this way will prevent many mistakes in drilling. www.americanradiohistory.com 456 Radio News for November, 1928 en The fiori Vavesi continent and from Australia, New Zealand and British New Guinea. RADIO NEws roill welcome any definite in- If this should catch the eye of your contributor, formation from readers un- our about Mr. E. Blake. whom I had the pleasure of meet- listed stations which you may hear putting ing in London some years ago, I hope he will listen on programs, only if you hear the call or in and try to hear us. We shall tie CJRX in the announcement of location. Please give with our regular broadcast station CJRM at Flem- the wavelength as closely as you can esti- ing, Sask., each afternoon, from 4:30 p. m. to mate it. Because of the number of experi- 7:00 p. m., Central mental Standard Time. This schedule transmissions by amateurs and will be extended in the near future. others, we cannot undertake to list such D. R. P. COATS, stations in the short -wave broadcast list on Radio Station CJR.II, 1018 another page. unless confirmation is re- Grain Exchange Building, Winnipeg, Can. ceived of their having a regular schedule; but all definite information received will be published here. Please consult data COSTA RICA STEPS OUT we have published before writing for in- Editor, RADIO NEws: formation; we hare no way to identify I have been getting a strange station in Costa a station by its program or language, since Rica (Central America). He is generally on many foreign stations transmit in several Saturdays, Sundays and Wednesdays, sometimes languages; nor even by its approximate other nights, from 10 to 11 p. m. Central Standard wavelength, unless it is one of the larger Time. He was first on about 38 meters, but of and best-known transmitters. late is using 30. He announces in English and Spanish; just what city and who owns the sta- tion, I do not know, but would like to find out. 1 would like to thank RADIO News for intro- WHO IS THIS ARGENTINO? ducing me to short waves; it is a great pleasure Editor, RADIO NEWS: to listen in at the bottom of radio. On April 20th I heard a station on about 30 or CHARLES J. SCHROEDER, 32 meters, from 6.25 to 9:15 p. m., E. S. T. 3125 No. Spangler St., Philadelphia, Pa. There were selections in German, Spanish and (Mr. Schroeder writes later: "I know for a fact English. At 8:25 the announcer said (in Spanish) it is not the Costa Rican government at San Jose, it was Buenos Aires, Argentina. I held on until because the announcer says that he is an amateur 11:20, but they had probably signed off. I will station. I received him again Sunday night at appreciate any information your readers can give 10:15 E. S. T. At 11 he said, I believe, '9:00 me. C. S. T., at Heredia, Costa Rica.' The next night Mr. Dobyns at the microphone (shielded from he mentioned JOHN J. HANNIGAN, JR., that his wavelength is 30.5 meters. the wind by boxes) of his short -wave station can't seem to get 35 Maple St., Norwood, Mass. I his call or name. I would like 6XBV, announcing the progress of the regatta to get his address, as I get him at times R5 to R6 from the official barge. with two tubes. ") NEW WINNIPEG STATION Editor, RADIO NEWS: SHORT-WAVE SPORTING ANNOUNCEMENTS The Winnipeg station, operating on 27 meters Station KGER, owned by C. Merwin Dobyns, of and heard by your correspondent, Norman Wiswell, Long Beach, Calif., has also a short -wave phone was not CKY, but IIC, owned by James Richardson transmitter 6XBV. During the recent Pacific and Sons, Limited. Tests were broadcast for sev- Southwest Exposition regatta held in Long Beach eral days by the Marconi engineer who installed harbor, this was used to transmit a description of the equipment. The regular wavelength will be the races to the main transmitter working on 25.6 meters and the call letters CJRX have been 215.7 meters, Owing to the carrying power of applied for, to take effect at the end of the present the short waves on 48.86 meters, it is quite pos- year. - sible they were heard much further than the higher - The tests were very successful. Reports of loud- power transmissions of the broadcast station. speaker reception have been received from the Yukon, from all' corners of the North American RIGHT IN THE MADDING CROWD Editor, RADIO News: I have received -a letter from PCJJ dated July 25th, stating they are now on the air from 1600 to 2000 and 2300 to 0200 G. M. T., Tuesdays (11 .11e. Tompkins' short wave receiver, described to 3 and 6 to 9 E. S. T.); 1600 to 2000 Thursdays: below, compactly built and including two extra and 0400 to 0700- and 1400 to 1700 Saturdays stages of transformer- coupled audio. (from 11 p. m. Fridays to 2 a. m. and from 9 a. m. to noon E. S. '1'.) on 31.40 meters. 1 am situated at Third Avenue and 52nd Street, New A NEAT RECEIVER York City; there as a power house around the Editor, RADIO NEWS: corner which always causes noise on the short The photographs show a short -wave set that I waves, and the "L" causes interference. I am have been using for about three months. It is of using a 50 -foot aerial of No. 12, and when recep- the same style as the "Junk- Box," but I have put tion is bad, I use an R.C.A. AG814 loop. 1 can in an aerial coil and find that it cuts out dead receive PCJJ on Tuesdays and Saturdays. 1 spots. The housing is an R.C.A. No. 5 cabinet, would like to hear from other fans located in the made of solid brass, into which I have built a middle of large cities how they get distance. sub -panel to mount my four sockets; under them WILLIAM MORITZ, are my two audio transformers and the choke coil. 843 Third Ave., New York, N. Y. You can see that this little outfit is very compact. It works wonderfully well on a "B" power unit, with 200 volts on a 171. I can get enough vol- SHORT -WAVE ON SUPERHETS ume to hear a block away on KDKA. NVA111C, etc. Editor, RADIO NEws: CHARLES B. 'TOMPKINS, In commenting on the communication from Baron 220 Broad St., Waverley, N. Y. von Iloyningend-Iuene, you ask if other owners of standard superheterodynes have received short -wave signals. JAVA FOR BREAKFAST When the L -2 Ultradyne was announced, I as- Editor, RADIO NEWS: sembled the set with considerable success but did I have heard Bandoeng, Java, on my RADIO NEWS not receive any short-wave signals. However, Short -Wave receiver, from my previous location at that was before broadcasting on short waves was St. Johns, Michigan, and have just received a con- as commonplace as it is now. firmation. (The letter says, "Yost heard us testing Last winter I assembled the Magnaformer 9 -8 on duplex telephony with Kootwijk- PCLL-on 18 to operate with A.C. tubes, at our winter home - meters. We are broadcasting Wednesdays from in south- eastern Florida. As an A.C. set it was 1240 to 1440 G. M. T. Would you report us? a failure (as I anticipated it would be if built in -Studio Radiodienst, Bandoeng. ") accordance with the published instructions) so 1 Mr. Tompkins' short-wave set in its old -style, FERRIS W. FITZPATRICK, rebuilt it to work on D.C. battery. but attractive, cabinet. Hq. Sect., Chanute Field. Rantoul, Illinois. I tried it only one day working on A.C. and www.americanradiohistory.com Radio News for November, 1928 457 the last program received was a musical number. there is no doubt that plenty of power helps a lot. and certainly did not have the ease in starting I do not remember the call letters, but the an- W. WALLACE CLENDENIN, that the fellows in the States enjoy. At present. nouncer was very distinct in saying "located at Culver City, Calif. after trying, and tedious, unsuccessful times with Bound Brook, New Jersey and broadcasting on a long -wave sets, I have reverted to short waves and frequency of 5,000 kilocycles." This was the only Editor, RADIO NEWS: can get plenty of good musical programs (barring well as time I ever had this experience but it shows that I have built several Ultradyne circuits. I found, the fading) as code. I also am a Scout, 16 years of age, and would it is possible for some supers at least to pick a few months ago, that by turning the condenser up and reproduce short waves with good volume. tuning the antenna cod completely 'out, I could be glad if you could put me in touch with two or A. B. GARDNER, tune in SUFI\ on their 62 -meter wave during three Scouts also interested in radio. It has been pretty hard 511 Green St... Dowagiac, Michigan. the afternoon with the oscillator condenser alone. here to keep pounding the old brass The tuning was very sharp, and there was rapid when nobody else is interested in that line; but once in a while a brother has along, Editor, RADIO NEWS: fading, but it could be done day after day. Our "ham" come and we have a good get the Re Baron v. IIoyningen- Heune's letter, are either reception of KDKA is very uncertain on their pretty time. Don't or both of his tuning coils reversed in the Ultra - broadcast wavelength; I don't believe we average idea that I'm lonely, though; the fellows all have a respect work I've have dyne? Reversing the primary coil lessens the anything like good reception on two nights a week, for the done, and I plenty pals. effectiveness of the set, of course, but makes it in summer. But as long as I used an Ultradyne, of The only thing that I sure would like is to have very interesting to handle. I could get their short -wave broadcasts in the someone in the old country to talk things HOWARD T. BEATON, afternoon. over with-chew the rag, so to speak. Iroquois Falls, Ontario, Canada. B. J. SANFORD, M.D., \ \'ell, GB till the next mag comes in. I would Clare, Michigan. be glad to tell the fellows anything they want to Editor, RADIO NEws: know. 73 to you. During the winter of 1926, I picked up one of EARL A. NOOSE, JR., .-IC 2 AJ, KIJKA's short-wave broadcasts, on an ordinary FOR SCOUTMASTERS AND SCOUTS American Bible Society, Pekin, China. Pressley superhet. This was one of their Far Editor, RADIO NEws: North programs, broadcast for Alaska and Northern Now that good radio weather is about to open USE OF SHORT -WAVE ADAPTER Canada, and came in on a dial setting that would up, maybe some scoutmaster might start a radio correspond to a wavelength of about 260 meters. club that could work with the one I have started Editor, RADIO NEWS: There was present the usual rapid fading, and here, and also have the real "kick" of talking to On June 19 I received a Submariner and attached the announcement stated that the broadcast was some American Scout who is in a foreign country. same to my Norde -Hauck Super 10, which has from KDKA's short -wave station, but I did not Personally, I think it would be about as fine a four audio stages, with a power tube in the last. get any statement as to which wavelength was training as any Scout could receive, and 1 would The results were very gratifying. Each night I being used. I never did pick them up in this man- be very glad to send my ideas or rather sugges- get the programs of SSS wonderfully and on ner again, and I think possibly the reason they tions to any scoutmaster who is willing to work. Sundays also, from 10:00 a. m. to 9:00 p. m., came in so strongly on this occasion was perhaps I have had' some wonderful results from the dif- Central standard time. 2 XAF comes in one week have due to their using the limit of their power. There ferent radio manufacturers, and they all daily and the next on Tuesday, Thursday and was nothing faint about their signals in this case: expressed a desire to help the good work along. Saturday. speaker with plenty of volume. Also, a lot of other letters have been received; but they came in on the Your program from 2XAL on July 31, from a super built up from the I have been too busy to take much time away from At present I am using 7:30 to 7:50 p. m., containing your talk about using their coils, but business to answer any but the. ones from Scouts. Silver -Marshall Lab. circuit. flying rockets and the orchestra numbers was having Scott World's Record intermediates. Using Will you return the enclosed letter (printed below) as an for heard but with severe fading. the plug-in coils, I can get down to about 26 to me, as I want to use it incentive PCJJ, Holland, broadcasts every meters. I think I must have been one of the first my boys to keep on trying. Tuesday front GEORGE O. HOWARD, 7:00 to 8:15 p. m. and on Fridays I enjoy to pick up RF \I in this country. I got them some- the Spanish program from 7:45 time last December, and played them regularly for 109 Tulsa Bldg., Tulsa, Oklahoma. to 9:00 p. ni. It comes in exactly between several weeks before I found out who they were. Dear Mr. Howard: 2X: \L and 2XAF; the RADIO NEws, I would readings on the Submariner 19, have been able to get KDKA on two wave- Having seen your letter in are 1934 and 20. I in lengths, WGY the sane, but not a thing from like to write in commendation of your idea ORESTES CENA, to the Scouts and getting them inter- Tuxpam, Vera Cruz, Mexico. \ \'RNY or WLW, though 1 am always trying. teaching radio three years experience (Continued on page 493) Short waves may carry well with low power, but ested. I am a "harm" of quecy. The piezo- Station PCJJ, that of the Philips electric con- trol is contained company at Eindhoven, Holland crystal in the box at (transmitter at Hilversum), which the left in the center (uppermost) picture. so many of our readers have It is ground to a heard, is probably the most frequency corres- powerful transmitter in the ponding to a wavelength over world putting out short-wave 180 meters, and the unit puts out 50 watts on Une broadcasts. Its total power is second har- monic of this. the about 15 kilowatts in the aerial, In middle and it works now on 31.40 me- section of the transmitter, shown ters. The illustrations which we at the louver left, the frequency reproduce show the compactness is tripled and the output raised of this installation; at such high to 3 kilowatts. At the right of frequencies, care must be taken titis picture. and the left of the that leads do not introduce oscil- third, is shown the 25 -kw. tube latory circuits, as regeneration which feeds the aerial -a single bronze Loire. The remaining ap- of 1 /20.000th of the power would cause difficulty. This is mini- paratus of the louver right com- mized by changes of the fre- prises the modulators and their cooling system. www.americanradiohistory.com 458 Radio News for November, 1928 The Radio Constructor's Own Pages Wherein Custom and Home Set Builders and Experimenters All Over the World Swap Experiences and Suggestions About Hookups and Accessories REJUVENATING AN OLD -TIMER FIRST X -RAY PHOTOGRAPHS OF RADIO MR. PORTER WILL BILL YOU RADIO NEWS: SETS .Editor, Editor, RADIO NEWS: Editor, RADIO NEWS: A short time ago, I got hold of one of the old I will send you and Mr. Porter my heartfelt Under the heading "X- Raying the Radio Set to Westinghouse receivers consisting of a type RA thanks for the permanent hook-up of a phonograph Show Its Insides," on page 206 of RADIO NEws tuner and a type DA detector -amplifier. This set, pick-up to a receiver (page 53, July, 1928 RADIO for September, Baron Manfred von Ardenne is as you may know, uses three tubes of the WD -12 NEws). I have a very expensive phonograph, and credited with the introduction of X -ray photog- type, which decided to replace with the present by a little expenditure and some of my own time, I raphy of wireless sets. UX type. I replaced the three sockets with UX- I have a neat job at a saving of about $500 com- Unless he did this before 1919, I believe I was type sockets and used a UX -200 in the detector pared with buying one of the new combinations. the first to employ X -rays for this purpose. I socket and UX -201A tubes in the two audio stages. This is a feature which, I suppose, appeals to the showed an X -ray photograph (which took in The second audio transformer was burned out, so I I majority of home constructors. I am using a 1919) of a wireless set to illustrate a lecture on replaced it with a Thordarson with a turn ratio SCIENCE AND INVENTION circuit of 1925, but it wireless telephony to the Royal Society of Arts in of 6:1. The grid leak and condenser I replaced works fine. London in 1920. (See. Wireless World," for July with a .00023 Sangamo condenser and a 4-megohm A. CARL CUTSINGER, 24, 1920). This radiograph, together with an ordi- grid leak. I used 45 volts on the detector plate 960 East Orange Grove Ave., Pasadena, Calif. nary photograph of the same set, is reproduced in and 90 volts on the plates of the audio tubes. For my book, History of Radio Telegraphy and Teleph- a loud speaker I used the Saal eccentric cone which, ony, published by Chapman & Hall, Ltd., London, in my opinion, is about the best speaker I have yet 1926. heard for torte quality and its ability to handle I shall be obliged great volume without blasting. if you will publish this letter in your excellent journal, to which have My aerial is about 150 feet long and 40 feet high I been a regular subscriber for many years. and is of the single- strand type. My ground sys- G. BLAKE, tem is somewhat out of the ordinary, in that one G. 8 -10 Onslow Road, Richmond, Surrey, England. connection is made to a water pipe while two other connections are made to two groups of three 1 -inch pipes driven into the ground; the groups are spaced MULTIPLE GROUND MAKES A FRIEND about 23 feet apart at right angles to each other. Editor, RADIO NEWS: With this layout I have been able to get what I I always read your magazine with the deepest consider surprising results, considering the fact interest and get lots of good out of it. For ex- that we in the Hawaiian Islands are located over ample, "Encircling the World with a Two -Tube 2,000 miles from the mainland. Set," in the March issue, made mention of using I have only been using this set for the last three several grounds. This was tried by a friend of days, but I am convinced that it outperforms a mine in Ottawa to whom I passed the magazine. certain well -known 6-tube set which I happened to The results were beyond expectation, and have be using on trial; it outperforms it, not only in made him a regular reader of your magazine. range, but in volume as well. The volume put out Others are to try the idea. With sincere thanks by this set is truly amazing; it not only fills my for the information contained in your recent letter. room but can be heard distinctly all over the house. J. PRUD1OMME, In the short time I have been using it I have al- 139 Botcher Street, Ottawa, Canada. ready logged the following stations: KGU, KGO, KFC, KPO, KHJ, KFSD, KOIN, KFI, KPLA, THANKING THE WRITER (COIL, KF \VB, KNRC, KYA, KNX, KMTR, Editor, RADIO NEws: KOMO, 4QG, 2BL, besides some others which I In keeping with your policy of giving us the could not make out because of fading. I am look- latest and best, you have again conferred a great ing forward to enlarging this list considerably in treat cn the Browning -Drake fans. In the August the very near future, even though this is claimed to issue of RADIO NEws, you published an article by be the worst season of the year for radio reception. Mr. C. A. Oldroyd, of Barrow-on- Furness (Eng- Since this set employs the regenerative circuit, land), "A Booster Unit for the Browning- Drake." tuning must be carefully done to prevent marring I built one of the "Boosters" and it has done the neighbors' reception; but my experience has wonders for that selective and wonderful DX- A rear view of 111r. Mampe's speaker, shoe.ing been is that it very simple to tune if one keeps in getter. The results are almost beyond belief. Dur- the three electrodynamic cones. mind the simple rudiments of tuning. I have no- ing this excessive heat and fearful static condi- ticed, however, that correct manipulation of the de- tion of the atmosphere, I have been able to bring LUCKY YOU WERE tector rheostat gives great flexibility. The ampli- in the Gulf State stations and the Atlantic coast, NOT FLYING fier rheostat, however, need not be touched in tun- with greater volume than is ordinarily obtained Editor, RADIO NEWS: ing; the best position is so that it is just turned during the fall and winter months. Also, I have Today I bought the June issue of RADIO NEws on. In this position it gives maximum volume with been able to get a great many of the low- powered and read "The Port of Missing Airplanes. ' The a minimum consumption of current and a conse- stations (some at quite a distance) which, under story is indeed a good one, and I believe it is quent lengthening of the life of the audio tubes. the best of conditions, are hard to bring in, and quite possible for a person to be overcome with It is very likely that there are others who have all of these on the loud speaker. dizziness by listening to a shrill note sent through one of these sets and would like to remodel it. It It is true that we have one more tuning control, a pair of headphones, as in the story. While lis- is for these that I decided to write you and tell but the results more than compensate, and, as the tening to my set, I decided to change the grid of my experiences, and for that reason I hope that dials "track" pretty closely, it is very little leak, still wearing the phones. The set started you will find it possible to publish this letter. trouble. to oscillate and the whistling made me dizzy. I O. F. STERNEMANN, J. N. BACON, am not telling you of this as a scientific experi- Box 9, Hatei, Hawaii. Oshkosh, Wisconsin. ment, but an actual happening. In closing, I wish to say that I greatly enjoy the stories printed in your magazine. O. Mampe of Palisade, N. 1., NILS GJERDE, opposite New York City, is a 5612 Sixth Ave., Brooklyn, N. 1'. radio constructor who goes in (Sonic for elaborate effects. He has of our readers are not in entire agree- ment as to tiro fiction RADIO NEWS built a speaker, with three elec- which carries. However, the series stories trodynamic -care units, whose ap- of referred to is, in our pearance is shown opinion and that of many others, worth reading here; the purely baffle board is 41 feet for the scientific considerations which it wide presents.) and 51 feet high, and made of h -inch wood. The three speaker units arc supported an shelves at OUT IN THE WOODS the rear, as will be seen from Editor, RADIO NEWS: the view in the third column; I feel a great deal of credit is due the World's and other shelves are provided Record Economy Eight, as I built one of these for the power supply and ampli- sets. I am spending the summer here and our fier. The reproducer assembly camp is in the heart of a large forest, and located in is admirably adapted for high such a way that I cannot put the aerial above the quality under control; though it trees. I am using 125 feet of aerial, including is hardly suitable to be tined lead -in, and have received forty DX stations in loose under frill power indoors. one week's time with no overlaps or interference Constructors who desire to build by other stations. Two of them are real DX at a speaker with even one dynamic this time of year, I feel; they are KFI and WKAQ. unit of this type are referred to I would appreciate your publishing this. ',ages 438 -441 of this issue for CHESTER L. PRICE, M. :Uampc's triple speaker, viewed from the front of the baffle. information. Wanakena, New York. www.americanradiohistory.com Radio News for November, 1928 459 SET BUILDING IN FRANCE A SENSITIVE FOUR -TUBER Editor, RADIO NEWS: Editor, RADIO NED S: Just a few lines of appreciation to yourself and I am sending my -tube which was RADIO NEWS, the current copy of which was a four circuit, very much like Mr. McCormick's the screen - boon companion to me during an exceedingly violent till tube came out. the real electrical storm up here (at Holzleck, in the grid I think that only difference was that I changed my antenna coil Vosges Mountains). I was far too deeply en- by the fixed and tap- grossed in your description of the Screen -Grid Stro- doing away with condenser ping at the twelfth from the filament end. 1 bodyne to notice such trifles as storms. I ha n turn have Mr. McCormick, advis'ng him to put taken RADIO NEWS since its first edition but, be- written a screen -grid tube in his R.F. stage; it requires cause of traveling all over the world, I had to a and is well worth the plan with my newsdealer in New York to hold only little changing it trouble. With his DX record, using a 201A, he over my copies until my return. Now that I have certainly should step out with the screen -grid hook- a permanent address in Paris, I have at last be- up for a few more miles. come a subscriber. This is very sensitive and selective with Here is something that would be of great as- circuit a short antenna, and west coast comes in with sistance to me and undoubtedly to many other the plenty of volume. fans over here, and that is a table comuaring the We have only from 7:30 p. m. until midnight relative sizes of wires between the American B & S do DXing, high-power gauge and the French gauge which is given in to any on account of the naval station NSS here, which sends off a heavy mils. I desire to build a Strobodyne a l' Ameri- mush or "back- wash so you can see ive do not caine, but cannot do so until I know what size "; wire is equivalent to that given. (See below). I have a shot at the foreigners. My most distant stations are Mexico, Cuba and fell down on the construction of the RADIO News California, Canada; Short -Wave set on this account and am anxious but remember we have to do this early. This pub- to complete it and fish for good old \VRXY on circuit was originally the "Reactodyne" the 30.91 -meter wave. lished by RADIO NEWS its 1924. I hope you can interest a We have not yet come to the screen -grid tube few others in this circuit. Mr. Ste-wart, above, flanked on either side by FRANCIS E. ENGLE, in France, but I have found that the "Metal a low -cost loud speaker made as described. Radio" factories are one on the market 14 Cathedral St., Annapolis, .l(d. putting It will be bard to lower his record unless you in the near future, and if it has similar char- steal a unit. acteristics to the 222, I shall build the Strobodyne S. G. as described. A SINGLE- CONTROL SHORT -WAVER I am at present using a Strobodyne built by M. being well coated with talcum powder to insure Chrétien, the originator of the circuit, but the its easy removal after the horn had thoroughly Editor, RADIO NEws: American hook-up is way ahead of it. My set dried. For the material, I used all the old maga- I am enclosing a diagram of a "one-hand" short- has coils for both wavebands (180 to 500 and 500 zines, newspapers, wrapping paper and so forth wave receiver I have been using for about four to 3.000 meters) incorporated, and the change is that was available, and for paste a mixture of flour months. I use Aero short -wave coils; with this made by a commutator on the panel. and water. The job was rather tedious; but, as arrangement I am able to set the feed -back con- By the way, the relay of the Tunney- Ilceney L am not especially fond of work anyway, it came trol condenser for a given coil and sweep th,s whole fight over Daventry and 21.0 was wonderful. I in handy to apply a layer or two a day and allow range without any other adjustment until the de- received it in Paris clear as a bell. Absolutely time for drying. The horn was finally built up to sired signal is found. Then a little adjustment of no fading right up to R'GY's announcement of near / -inch in thickness, but is still too thin. Only the detector filament and I am all set to listen. the time signal, when England acknowledged the one brace is used, that being made of four pieces No more "holes," etc. defeat of her champion with silence immediate and of wood, )1 -inch square and about twelve inches I am using special R.F. chokes. \\'hile an profound. But that relay certainly spoke worlds long, nailed together in the form of a square and Aero No. 10 will work very well, a choke with very of the future of radio from an international view - slipped down on the bell as far as it will go and low inductance must be used on S. W. I use No. point; may good old RADIO NEWS stick and grow pasted in position. The tone is as good as that of 36 S.C.C. on a piece of round or square Vs -inch with it.. several manufactured horns I've heard, and better bakelite, about 6 inches long; start winding otoz R. W. HuMPHRE.YS, than some. end about 40 turns, space %-inch, then 60 turns, 57 Boulevard Suchet, Paris 16e, France space 1/s -inch, 80 turns, and so on till the space is The cotte consists of one layer of heavy brown used up. I find the 112A tube the best detector wrapping paper with two layers of newspapers Metric Measurements of Wire the rest is standard. pasted on the for this receiver; outside, three layers in all. A circle W. E. SMITH, ( Fiere arc the measurements of copper wire 36 inches in diameter was laid off out this and a - Oak Forest, Illinois. the metal conductor only -in the metric system: the V- shaped slice cut out. That gave me a cone 34 diameter in millimeters and the area in square inches in diameter and 7 inches deep. A loop of millimeters. This may be of benefit to some of soft copper wire was pasted on the outer edge and our other friends abroad. The gauge is Use familiar the string used cone for mounting the in the IS NOT SOLELY TO BLAME American Brown & Sharpe.- Eotroa.) square wooden framework was laced back and forth MR. LOVELESS Gauge Diam. Area Gauge Diam. Area through the wire and to the frame. A 1 x 2 Editor, RADIO NEWS: 14 1.628 2.081 28 0.321 0.081 bolted to the frame, a supports cigar box, which, I was interested in finding in the article on the 16 1.291 1.309 30 0.255 0.051 in turn. supports one the driving unit, taken from Loveless aerial the description of a circuit embody- 18 1.024 0.823 32 0.202 0.032 a Musicone. The main item of expense in this big ing the principle of my patent No. 1,668,261, 20 0.812 0.513 34 0.160 0.020 cone was five 1 cents for the two bolts in the x 2; issued to me by the patent office May 1, 1928; 22 0.644 0.325 36 0.127 0.013 the flour for paste was the stolen from the family application for the same having been filed Dec. 27, 24 0.511 0.205 38 0.101 0.008 larder, so cost nothing. 1923. An examination of this patent will reveal 26 0.405 0.123 40 0.080 0.005 The cone is by far the better of the two. Both the validity of my claim; for it will be there seen reproduce well the bass and middle- register notes; that specific claim is there made for aerial circuits but we have lots static together with a claim embodying the same principle NO PANCAKES FOR BREAKFAST of down in this hot country and it is not so objectionable on the cone as on in radio sets themselves. The discovery of the Editor, RADIO NEWS: the horn. The set driving these speakers is home - principle involved was made by me as far back I attach a snapshot of two speakers made of built, a Browning -Drake type, with a screen -grid as 1920, while engaged as professor of physics its scrap paper, a cone and a horn built along the R.F. stage, 200A detector, Thordarson Autoformer the University of Santa Clara. lines of the model described in Chester Schenck's audio amplifier with a UX -112 in the last socket. (Rev.) RICHARD H. BELL, S. J. article in the June issue of RADIO NEWS. The \ olume amt quality de luxe! St. Ignatius College, 2130 Fulton St., horn was built around a form made from an old GtY STEWART, San Francisco, Calif. orange crate and some stiff cardboard; the forni U opio, Texas. (Continued on page 498) 35T 47T 26D.CC. 22 D.C[ -.00015 MMF 2zz ¡ 2OI-A 201-A 71-A j j Ir r - I I 2-A , iFiY °°fiVi _ áó 47 22DLC h t b O 6 BND, A- C4 -A+B= B+45v. 'C=4;V. '8". 90V. -C-27V. '8+135V. Mr. Engle's hook -up differs from the " Reactodyne" in its aerial circuit; the latter was Mr. Smith's set is tot a reflex, as first glance might sug- very loosely coupled in the original. The primaries are wound fumble -fashion and placed gest, but a short -waver with two A.F. amplification stages. inside the secondaries, which are on 3 -inch tubing. Transformers are 5.31 220s. Ile Our readers may test it to see if ease of operation is accom- suggest a fixed ballast also in the 222's "A-." panied by necessary sensitivity and control. www.americanradiohistory.com 460 Radio News for November, 1928 adïo News LAB(RATORCE e rneltsnco praforie5 manufacturers arc invited to send to RADIO NEWS LABORATORIES meats. No "write -ups" sent by manufacturers are published in these pages, RADIOsamples of their products for test. It does not matter whether or not and only apparatus which has been-tested in the Laboratories and found of they advertise in RADIO NEWS, the RADIO NEWS LABORATORIES being an inde- good mechanical and electrical construction is given a certificate. As the sere- pendent organisation, with the improvement of radio apparatus as its aim. vice of the RADIO NEWS LABORATORIES is free to all manufacturers, whether /f, after being tested, the instruments submitted prove to be built according they are advertisers or not, it is necessary that all goods to be tested be for- ro modern radio engineering practice, they will each be awarded a certificate warded prepaid, otherwise they cannot be accepted. Apparatus ready for, or cf merit; and that apparatus which embodies novel, as well as meritorious already on, the market will be tested for manufacturers free of charge. Appa- features in design and operation, will be described in this department, or in ratus in process of development will be tested at a charge of $2.00 per hour the "What's New in Radio" department, as its news value and general interest required to do the work. Address all communications and all parcels to RADIO for our readers shall deserve. If the apparatus does not pass the Laboratory NEWS LABORATORIES, 230 Fifth Avenue. New York City. Readers will be in- tests, it will he returned to the manufacturer with suggestions for improve. formed on request if any article has been issued a Certificate of Merit. AUDIO -FREQUENCY and the device is identified by a LABORATORIES CERTIFICATE The diameter of the base is 21/4 TRANSFORMER "mandarin red "' spot. OF MERIT NO. 2423. inches and the height over all 2V The "Type AX" audio -frequency AWARDED THE RADIO NEWS inches. The device has proved satis- LABORATORIES CERTIFICATE factory in giving smooth control of transformer shown, submitted by the PHONOGRAPH PICK -UP Sangamo Electric Company, Spring- OF MERIT NO. 2422. volume when used with the pick -up field, III., is of excellent mechanical The "Via-Rad" phonograph pick-up manufactured by the same concern. device shown, submitted by the and electrical design. The amplifi- AC- OPERATED RECEIVER cation of the transformer maintained Brooklyn Metal Stamping Corp., constant from 32 to The "Packard" 8 -tube radio re- 718-728 Atlantic Ave., Brooklyn, a value almost Pack- 5,000 cycles, when used with the ceiver shown, submitted by the N. Y., is of the magnetic type and 201A -type tube. The primary in- ard Radio Co., 2161 No. California makes it possible to reproduce speech is of all - ductance, with a plate current of Ave., Chicago, Ill., the and music from ordinary phonograph using five 226 A.C. is 3 milliamperes, was found to be electric type, records, when it used in connec- approximately 80 henries. The tubes, one 227 A.C. (heatéd- cathode) tion with an audio -frequency ampli- transformer has a ratio of three to detector tube, and two 171 power fier. It is of the balanced- armature rie; and excellent quality with great tubes; it operates directly from the type; the airgap between the pole volume was obtained when it was 110 -volt, 60- cycle, house- lighting cir- pieces is adjusted in the factory be- used in the conventional audio am- cuit. The low -voltage A.C. current fore sealing. The magnets are of is plifier employing the 201A and 171 for the filaments of the tubes the bar type and situated on each tubes. The transformer is identified supplied by separate windings of the side of the adjustable pole pieces by a yellow spot. The core and power transformer, and the "B" in such positions that their fields -wave AWARDED THE RADIO NEWS winding are completely shielded by voltages are provided by a full assist. Their magnetic strength is 280 type in connec- LABORATORIES CERTIFICATE an iron housing of olive -green finish. rectifier of the great, resulting in a very sensitive OF MERIT NO. 2425. The dimensions of the base are 2% tion with an efficient filter system, and loud reproducer. The frame or of which are contained arma- x 2h inches, while the height is 3 the chokes base which supports the coil, inches. in the same metal housing with the ture, and pole pieces, the dimensions PHONOGRAPH PICK -UP stages of AWARDED TI1E R. \DIO NEWS power transformer. Three of which are 11/4 x 2 inches, is cast ADAPTOR LABORATORIES CERTIFICATE tuned radio frequency of modern de- The "Via -Tector" home broadcas- OF MERIT NO. 2421. sign, using 226 -type tubes, give am- ter and pick-up adaptor device ple selectivity and sensitivity. The shown, submitted by the same manu- tuning inductors are of the compact, facturer, is of the UX type and small -field type, enclosed in indi- designed to be plugged into the de- vidual shield cans. The radio -fre- tector socket of the radio receiver. quency stages are followed by a If it is so desired, the detector tube conventional 227 -type detector, which may be plugged into the adaptor; feeds into two stages of transformer - thus utilizing this tube as an addi- coupled (1:1 ratio) audio frequency, tional stage of audio frequency. -pull followed by a stage of push Otherwise, the tube may be replaced power amplification of the 171 type. by a jumper, which is plugged into The speaker windings are protected the socket, thus allowing The of aluminum alloy. The end of the only the by a balanced output choke. audio -frequency stages of the set to tuning of the R.F. and detector cir- balanced armature protrudes through the metal housing and carries at its function. The device is of black cuits is accomplished by one control, molded bakelite and approximately which is .geared to the common shaft end the socket and fastening screw of the condenser rotors; the scale is for the phonograph needle. The de- of the drum type. A fine adjustment vice is fitted with a flange, de- of tuning for DX work is accom- signed to fasten over the tone arm plished by means of the levers pro- of the phonograph after the usual AUDIO -FREQUENCY CHOKE truding through the panel on each reproducer has been removed. The The "Type E" audio- frequency side of the tuning control. A power over -all dimensions are 2j inches choke or "impedance" submitted by rheostat with a panel voltmeter is long, 2 inches wide, and 1g inches the same manufacturer, is of the provided. to maintain the filaments high; and the weight 8 ounces. The same size and shape as their "Type housing is of a gold - finish. AX" A.F. transformer illustrated AWARDED THE RADIO NEWS above. It is used as an output im- LABORATORIES CERTIFICATE pedance for the 171 -type power tube. OF MERIT NO. 2424. in which case the entire inductance the size of the standard UX tube is employed. It may he used also base; it is provided with a four - as an output impedance for the 112 - PICK -UP VOLUME CONTROL foot extension cord, the tips of or 210 -type power tubes, by using The "Via -Trot" phonograph pick- which may be plugged into the vol- the portion of the winding between up device volume control shown, sub- ume control described above. "T" and "B } "' It is designed to mitted by the same manufacturer, AWARDED THE RADIO NEWS match the impedance of the modern of the tubes at the proper tempera- is of the graphite -and -powdered -mica LABORATORIES CERTIFICATE power tubes and, for this reason, ture. The control at the right of compression type; it has a resistance OF MERIT NO. 2426. allows the lower frequencies to be the set is provided for controlling range from 0 to 500,000 ohms and better reproduced. When it is em- oscillations and volume, and there is is to be shunted across the terminals rloyed in the output circuit, a block- a sub-panel adjustment to balance of the phonograph pick-up device. A.C.-OPERATED RECEIVER ing condenser external to the choke out the hum in the R.F. and 1:1- This resistor is provided with cord- The "Model 801A" radio receiver must also be used; this should have ratio audio stages. The filament tip jacks, two on each side of the shown, submitted by the Stewart - f rom 2 to 4 tuf. capacity, and be circuits of the detector and the housing; the tips of the pick -up are Warner Speedometer Corp., 1834 of voltage rating suitable to with- power tubes are automatically bal- plugged into one pair of jacks, while Diversey Parkway, Chicago, Ill., is stand safely the maximum voltage anced by center- tapped windings. The those of the receiving -set adaptor of the all- electric type and operates of the power stage. The inductance receiver is of attractive appearance, are plugged into the other pair. The directly from the 110 -volt, 60 -cycle was found to be within 10% of and its operation, with regard to case or housing is of brown molded house current. The receiver uses the rated value of 30 henries, when sensitivity, selectivity, quality, vol- bakelite of pleasing appearance, the four 226- types, one 227 -type, and measured at 60 cycles; the ohmic ume, and elimination of the A.C. top is of gold- finished die -stamped one power tube, in three stages of resistance is approximately 570. The bum, is satisfactory. metal, and the adjusting knob is tuned radio frequency, detector and metal case is finished in dark red AWARDED THE RADIO NEWS molded of the same colored bakelite. two stages of audio frequency; the www.americanradiohistory.com Radio News for November, 1928 461 power stage being of the 171 type. tubes, and operates directly from AWARDED THE RADIO NEWS speaker cords. One terminal of each The "B" voltages are supplied by a 110 -volt, 60 -cycle current. The "A" LABORATORIES CERTIFICATE speaker is inserted in one of the full -wave rectifier of the 230 type, current is supplied by a step-down OF MERIT NO. 2430. holes marked 2, while the remain- and smoothed well by an efficient transformer from the A.C. line to ing two terminals of the speakers filter system. The filament current a rectifier of the dry type. The is supplied by special windings on NEON TELEVISION TUBE the power transformer. The com- The "Telion" neon tube illus- pact tuning inductors are of the trated, submitted by the F. & II. small -field type and located under Electric Corp., 68 Springfield Ave., the metal chassis. Four tuning con- Newark, N. J., is designed espe- densers are arranged in tandem, cially for television' work. Its with rotors fastened to a common "striking voltage" as measured, was shaft; the drum is calibrated in found to be approximately 180 volts. wavelengths as well as degrees, and the current at the "dark point" 11 controlled ' . kno'i on the panel low -voltage, pulsating uni- directional milliamperes. The recommended current is then properly filtered until safe average current is 50 milli- all trace of A.C. hum has been amperes, although the maximum cur- eliminated. A voltmeter and rheo- rent may reach 125 milliamperes. stat are provided, so that the fila- The tube gave a uniform glow and are connected into the holes marked ment voltage may be adjusted and did not become spotty with changes 1. The internal construction is that maintained at the proper value. The of current at high frequencies. It of a double -pole, double -throw rotary is with a base of "B" voltages are supplied by a full - fitted the UX switch; contact springs are arranged wave gas -filled rectifier tube in con- along the top of the switch mount- nection with the necessary filter sys- ing to receive the ends of the cord tem. Three stages of tuned radio tips, which pass through the molded frequency with shielded coils are housing. The operation of the switch employed for selectivity and sensi- was found to be satisfactory for the tivity. The oscillation control is use designed. placed on the panel so that maxi- AWARDED THE RADIO NEWS mum sensitivity may be obtained at LABORATORIES CERTIFICATE all wavelengths. A tuned detector OF MERIT NO. 2433. is followed by two stages of I:1- of -the set. A volume control is ratio audio frequency of the con- provided, which serves also as an ventional type which feed the ampli- oscillation control on the shorter fied impulses into a stage of push - PLUG -IN COIL FORM wavelengths. The receiver is pro- pull amplification of the 171 power The "plug -in coil" form shown, vided with connections for long or type. submitted by Silver -Marshall, Inc., short aerials or. if preferred, the The speaker windings are pro- 846 W. Jackson Blvd., Chicago, Ill., 110 -volt line may be used as the tected by an output choke of bal- is of the UY- or 5- prong -type, de- antenna. anced type. The tuning of the R.F. signed to be plugged into any Uy A cone speaker of the balanced- and detector circuits is accomplished socket. Its over -all height is 2% armature type, approximately 6 by one control of the drum -scale inches and it provides 11/4 inches inches in diameter and enclosed in type, which operates the common winding space on a tube 1% inches a metal housing. is attached to the shaft of the condenser rotors; fine type. The glow electrode has a sur- in diameter. The secondary wind- cover of the radio receiver, making adjustment is obtained on the tuned ing space is threaded with 75 turns the receiver entirely self -contained. circuits by the operation of levers face 1 -7/16 inches square, and is The housing of the set and speaker protruding through the panel on made of a special material to pro- is finished in a brown crystalline either side of the tuning control. mote uniformity of glow with very finish. The combination is small in The receiver has an attractive ap- small currents. size, lmt was found to be satisfac- pearance, and its operation with re- AWARDED THE RADIO NEWS tory in regard to sensitivity, selec- gard to selectivity, quality and vol- LABORATORIES CERTIFICATE tivity, quality and volume. ume is satisfactory. OF MERIT NO. 2431. AWARDED THE RADIO NEWS AWARDED THE RADIO NEWS LABORATORIES CERTIFICATE LABORATORIES CERTIFICATE MICA BALANCING CONDENSER OF MERIT NO. 2427. OF MERIT NO. 2429. The "Micrograd" small adjust- able balancing condenser, submitted VACUUM TUBE A.C. VACUUM TUBE by the Pilot Electric Mfg. Co., 323 The "Type 01B" vacuum tube il- The "No. 22" vacuum tube shown, Berry Street, Brooklyn, N. Y., is lustrated, submitted by the C. E. submitted by the Arcturus Radio of the mica-dielectric type, designed Manufacturing Co.. Inc., 702 Eddy Company, 255 Sherman Ave., New- for neutralizing or compensating to the inch, which allows the con- St., Providence, R. I., has the same ark, N. J., is an A.C. screen -grid radio -frequency circuits. It was struction of a space -wound plug-in general characteristics as the 201A tube of the indirect-heater type, em- found to have a variable capacity coil of modern design. The lower ploying a cathode emitter which is range between 6 to 50 micromicro- end of the form is provided with a heated by a filament of carbon, whose farads. The variation is accomplished slot 1/16 -inch wide and 1 -inch deep filament consumption is 0.35- ampere through adjustment of the small for a primary or tickler winding of at 15 volts. An amplification of the bunched type. The five prongs 400 at 1,000 cycles was obtained provide for the use of the coil as a with the sample submitted for test; short - wave three - circuit coupler, with 135 volts on the plate, 11/4-volt when the filament and ground ends "C" bias on the control -grid, and a of the secondary and primary are shield -grid voltage of 45, and using made common to the cathode prong. The a plate load of 1 megohm. An form is molded of black bakelite amplification of from 25 to 60 at and provided with a reenforced rim radio frequencies was obtained with knob, either by hand or by the use at the top, to prevent damage to the output coupling impedances of dif- of a screw- driver; this compresses completed coil when removed from ferent types. The measured con- or loosens the curved spring -brass the plug -in socket. ductance at 1,000 cycles was found plates, which are separated by mica, AWARDED THE RADIO NEWS to be approximately 445 micromhos, thus increasing or decreasing ca- LABORATORIES CERTIFICATE the plate impedance 900,000 ohms. pacity. The housing is of black OF MERIT NO. 2434. The tube may be used successfully molded bakelite and requires a sub - panel or base -board space 2 x 1 tube, which it may be used to re- inches. The overall height, with the place when provision is made for the adjusting screw at minimum. capac- SCREEN -GRID A.F. COUPLING lower filament consumption of /s-' ity, is approximately 11/4 inches. UNIT at 5 volts. ampere (125 milliamperes) AWARDED THE RADIO NEWS The "Type -223 Hi-Mu" The amplification constant (taken LABORATORIES audio CERTIFICATE transformer shown, submitted by from a set of four tubes) is ap- OF MERIT NO. 2432. the same manufacturer, his been de- proximately 9, with a plate imped- ance at 90 volts of approximately 10,000 ohms. The tube is equipped SPEAKER CONTROL SWITCH with a standard UN base and its The loud- speaker control switch operation as a detector or amplifier shown, submitted by the Fisch Radio is found to be as satisfactory as Company, 1233 Hoe Ave., Bronx, that of the 201A -type tube. N. Y., allows the listener to oper- AWARDED THE RADIO NEWS ate either of two speakers separately LABORATORIES CERTIFICATE or both simultaneously, connected in OF MERIT NO. 2428. series. This is advantageous when a speaker designed for reproduction of high notes and one designed for A.C.-OPERATED RECEIVER reproduction of low notes are used The "Metrodyne" eight -tube radio together. It is of black molded receiver shown, submitted by the as an A.C. screen -grid R.F. or A.F. bakelite, 244 inches long, 11/4 inches signed as an output coupling de- Metro Electric Company, 2171 No. amplifier tube, a space -charge or thick and 21/4 inches high. On its vice for a screen -grid tube or California Ave., Chicago, Ill., is of screen -grid detector, or a space - curved top are found four holes for other hi -mu vacuum tube. It pro. the electric type, using 6 -volt D.C. charge audio amplifier. the insertion of the tips of the (Continued on page 507) www.americanradiohistory.com 462 Radio News for November, 1928 1:'ppl.tllllÍll Conducted by C. W. Palmer RADIO NEWS readers send in every month an average of 5000 letters those asking for sketches, diagrams, data, etc.. should send TWENTY - asking information on every phase of radio theory, construction and FIVE CENTS FOR EACH QUESTION : failure to enclose this will cause delay. operation. We can only print the five or six replies which are of We cannot answer for this sum questions requiring original research, widest general interest. intricate calculation, or patent investigation; we cannot compare the Other letters will be answered by mail, if inquirers observe these rules: merits of trademarked apparatus, or give constructional data on apparatus BE BRIEF: TYPEWRITE OR WRITE LEGIBLY IN INK ON ONE SIDE OF THE whose makers withhold it. We cannot undertake to answer more than SHEET ONLY ENCLOSE A STAMPED ENVELOPE ADDRESSED TO YOURSELF. THREE QUESTIONS 18 each letter. If you inquire concerning a Circuit Many letters are not readable. Simple questions will be answered free; which is not a standard, published one, enclose a diagram to save delay. BY- PASSING AUDIO AMPLIFIER connected in order to improve the results. The isfactory with A.C. sets, since it unbalances the (2307) Mr. R. W. Wilson, Portland, Maine, condensers should be placed close to the trans- filament circuit and introduces a considerable bum. writes: formers, so that the audio -frequency currents will The grid returns for the 226 tubes may be con- (Q.) "I understand that most audio -frequency not have to travel through much of the wiring in nected according to several easy methods. The amplifiers can be improved by the correct use of the amplifier or through any of the leads to the balancing consists merely of finding the exact elec- by -pass condensers. .Can you explain where these power units. trical center of the filament circuit, so that no condensers should be used, their values, and just alternating voltage from the power supply will be impressed on the grid. Naturally, since this current what advantage they supply to an amplifier of this REDUCING THE HUM IN A.C. SETS type ?" is an alternating one, it must be kept entirely out Mr. (A.) Audio-frequency amplifiers are often con- (2308) B. Brown, Miami, Florida, writes: of the grid circuit. . am structed in such a way that a common coupling is (Q.) "I constructing a receiver with two Three methods of obtaining the electrical center unavoidably formed by the power unit or common stages of radio- frequency amplification and two of of the filament circuit are shown in Fig. Q. 2308A, "B" audio -frequency amplifica- battery. This coupling provides an excellent tion, path for feed -backs, from which a large amount of using the 226 tubes distortion may result. This trouble may reduced in the radio -frequency be and first audio very easily by the proper use of by -pass condensers -frequency between the various circuits. These condensers positions, a 227 in the de- provide a lower resistance path for the audio -fre- tector and a 171 in the quency currents than the artificial coupling. Of course, the direct current passes through the usual The voltage on the fila- circuits, since it is blocked by the condensers. You ment alternates, except at will find two diagrams showing how by-pass con- its center, which is a densers should be used in an audio -frequency am- "node" or point of uni- plifier in Figs. Q. 2307A and B. The first repre- form potential. On the sents any audio -frequency amplifier with trans- "Wheatstone bridge" former coupling, resistance coupling, or any type principle, a resistance of "impedance" coupling. Condenser Cl is the shunted across this must usual by -pass condenser connected between the contain a point of identi- plate of detector V1 and the negative filament. The cal voltage, located by plate circuit of each amplifier tube is completed by the sliding arm. connecting a 1 -mf. by -pass condenser between one of the filament terminals and the positive "B" terminal of the transformer. These condensers are last audio -frequency stage. I am rather puzzled B and C; these methods are the most common in shown at C3 and C5. A separate path is also about the grid returns and he methods of keeping use at the present time. Fig. A shows the use provided for the grid currents by placing by -pass the A.C. hum at a minimum. Can you give me of a resistor with a sliding contact which can be condensers of % -mf. or more capacity between the any data on this subject ?" adjusted for the minimum amount of hum. This transformer secondaries and the filament terminals (A.) The method of balancing out the audio - resistor usually consists of a potentiometer of about These condensers are represented at C2 and C4. frequency noises in an A.C. receiver is a rather 15 ohms shunted across the center of the filament The diagram in Fig. Q. 2307B represents the puzzling problem for the average radio fan. The transformer. This method is a very good one, since usual transformer -coupled audio -frequency amplifier usual method of connecting the grid return directly it is often found that the actual center of the and shows how the by -pass condensers should be to one side of the filament supply circuit is not sa - filament circuit is slightly to one side of the theoretical center. Fig. B is similar to Fig. A except that a fixed COUPLING TRANSFORMERS, center tapped resistor is used. This method is not quite RESISTORS OR IMPEDANCE UNITS as efficient as the one shown in Fig. A, since if the center tap of the resistor does not balance V3 the secondary of the power transformer in refer- G _ V2 P ence to the ground, the filament circuit will be LOUD unbalanced. However, in most cases it is very SPEAKER satisfactory. Another method is shown in Fig. C, which has the same defect as the method shown in Fig. B. This method employs a center tapped filament transformer for the filament supply, but is also very satisfactory for general uses. It is best to use a separate resistor for each grid return rather than try to use one resistor for all of the tubes, since in this way, each tube is balanced in respect to its own filament circuit. The wiring to the filament circuits of the A.C. tubes should be done with twisted wires, well insulated and kept as far away from the grid circuits as possible. This wire must be quite heavy (No. 14 at least), to pass a considerable current. The use of resistors for the grid returns of tubes in a radio -frequency amplifier sometimes results in instability or oscillation in the amplifier. How- A- A+ BI- B+ ever, this difficulty can easily be overcome by con- necting fixed condensers between the center tap C+ B- DETECTOR AMPLIFIER of the resistor and each side. These condensers Q. 2307A should have a value of .005 -mf. Alternating impulses are kept out of the "B" battery, which is common to all circuits, by the Grid Bias use of suitable condensers which divert them to the grounded filament. Cl is an R.F. by -pass; This is another point which causes considerable C2 and C4 block the "C" voltage, and C3 and CS the "B" voltage from the filament while confusion in the construction of A.C. receivers. completing the A.F. circuits. %Vlsen the negative grid bias for the radio -frequency www.americanradiohistory.com Radio News for November, 1928 463 ment of this important means of communication, and particularly aids in the exchange of radio in- formation of a technical and engineering nature -" Membership "There are four grades of membership in this Institute; namely, Fellow, Member, Associate and Junior. All the benefits of membership are avail- able at once to all new members of any grade, except that Juniors are not eligible to vote. Mem- bership means, also, that one is enrolled with others having a similar interest in radio, and that one is on record as being among those who are interested and active in the development of this new and useful branch of the engineering industry. "The grades of Fellow and Member require a much higher degree of technical training and ex- perience than the grade of Associate. In order to maintain a high standard of membership, the Board of Direction in each case very carefully scrutinizes the applications for Fellow and Mem- ber grades. "Before applying for membership in any grade the applicant should carefully read the Constitu- tion of the Institute to ascertain for which of the several grades he is eligible. An extract from the Constitution dealing with admission, eligibility, fees, etc., is printed on the back of the application form headquarters. Schematic circuit of the arrangement in Fig. Q. 2307A when transformers are used. Cl may be obtainable from the Institute's When filling in the application form, the applicant should from .001 -mf. up; C2 and C4 are usually 0.25 -mf., C3 and C5, 1 mf., though such values are not critical. submit the names of those persons who have knowl- edge of his professional experience, rather than those who have a high professional standing, but audio -frequency in an OF RADIO ENGINEERS amplifier and amplifier tubes THE INSTITUTE cannot vouch for him." A.C. set is to be obtained from the "B" power (2309) Mr. A. T. Kenny, Spokane, Washington, uit, a separate resistor may be used to supply writes: History the voltage to each grid or one common resistor with (Q.) "I have frequently encountered the letters "Prior to the formation of the Institute of Radio the correct taps may be used for the complete I.R.E. in electrical and radio publications and 1 Engineers, two other organized groups of radio supply. When 226 tubes are used in a radio - have wondered just what the Institute of Radio enthusiasts held meetings in New York and Bos- frequency amplifier, the plate voltage should be Engineers was founded for and what their aims ton. These were the Wireless Institute and the 135 volts and the negative bias 9 volts, in order to are. Of course, I realize that every large engineer- Society of Wireless Telegraph Engineers. On May give the greatest amplification and the quietest ing profession has its society; but I am particu- 13, 1912 these two organizations were merged, operation. Because each of the tubes requires the larly interested in this Institute and I would appre- taking the new name of the Institute of Radio same bias, a single resistor can be used for all of ciate any information that you can give me." Engineers. Headquarters were established in New the tubes. The method of connecting this resistor (A.) We have received a number of inquiries York. The Society of Wireless Telegraph Engi- is shown in Fig. Q. 2308D. It will be noticed that about this society, and because we believe that the neers had a membership of eleven in 1907 and the center filament terminals of these amplifier data will be of interest to a number of our readers, forty -three in 1912. The Wireless Institute had tubes are connected to one side of resistor RI, we are reprinting part of the information contained fourteen members in 1909 and twenty -seven in while the other side and the grid returns con- in the 1928 Year Book of this Institute. 1912. The Institute of Radio Engineers, at the nect to ground and to the negative "B" battery "The Institute of Radio Engineers functions time of its foundation, had less than fifty paid-up terminal. solely to advance the art and science of radio members." lts membership is now about five The value of resistor Rl can he easily deter- communication. It numbers among its members thousand, four -fifths of them in the United States. mined with the aid of Ohm's Law, wherein R nearly all of the men who have been prominent in Application blanks and information can be ob- equals E divided by I. R represents the unknown the development of "radio in the United States, as tained by addressing the Secretary of the Institute resistance required, E represents the biasing volt- well as many noted engineers and scientists in at the Engineers' Building, 33 West 39th Street, age, and I the plate current of the tubes for which other countries. New York City. the grid bias is required. To give the least amount "The membership of the Institute consists of for any of its of hum, the plate current should be 3 milliamperes those persons who are qualified ELECTROLYTIC "B" POWER UNIT and the plate voltage 135 volts, for each tube. The several grades of membership, either through their correct value of the "C" bias for this plate voltage interest in radio communication, or by practice (2310) Mr. H. A. Wilkins, Cleveland, Ohio, and current will be found to be 9 volts. If we of some phase of radio engineering as a profession. writes: have three 226 tubes requiring "C" bias, the total The eligibility of an applicant to membership in (Q.) "Will you please supply me with instruc- power plate current will be 9 milliamperes, or .009 am- any grade is finally determined by the Board of tions for making an electrolytic "B" unit pere. Substituting these values in the equation Direction of the Institute, in most cases on the to operate on the 110 -volt 60 -cycle electric -light given above; R equals 9 divided by .009, or 1,000 recommendation of the Committee on Admissions. line? I do not wish to use a transformer in this ohms, which is the correct value for the resistor "Through the presentation and publication of unit as I require only about 90 volts' for the radio - RI. The condenser C6 in the diagram is used original papers, by affording its members the oppor- frequency and detector tubes in my receiver. I am to by-pass the radio -frequency currents around tunity of meeting to discuss radio problems, by using a power pack with an audio -frequency ampli- resistor RI. This condenser should have a value awards of honors and prizes, and in other ways, fier, but the rectifier employs a 216B tube and will the develop- not supply sufficient current for the rest of the set." of about 1 -mf. the Institute fosters and encourages 226 L2 226 L3 227 T1 226 TO REST OF A. F. AMPLIFIER CI ONO R2 ow R3 \ R4 sss 2.5 VOLTS A.C. C6 R1 lsl OIMME. 1.5 VOLTS A.C. 0 8 . 8+ DETECTOR o g+AMPLIFIER Q. 2308D A typical A.C. hook-up; the value of resistor Rl depends on the plate cur- value suitable ta maintain Nie higher bias on the power tube. The floati, g rent of the two R.F. amplifiers and the first A.F. amplifier, which it biases. circuit of the detector, which' uses a grid leak and condenser, is based on the It keeps the center points of the filaments at, say, 9 volts above ground, to cathode of Nie 227 tube. The value of the resistors R2, R3 and R4 is which the grid leads return, In the last stage a resistor must be used, of negligible in computing the voltage drop, www.americanradiohistory.com 464 Radio News for November, 1928 One 20- or 30 -ohm rheostat, depending on whether a 201A or 199 tube is used (Rl); One .001 -mf. fixed condenser (C3); 30 HENRIES Eight binding posts; One 7 x 12 -inch panel; One 8 x 12 -inch baseboard, % -inch 11111 11111 90 thick; B+ Two 3 -inch tubes 3 inches long CHOKE for coils; CHOKE No. 22 D.C.C. wire; screws; wire for ccanee- ..*-100,000 tions, etc. OHMS The first point in constructing the set is to make the coils. . The aerial coupler is wound e with 12 turns of No. 22 double -cotton -covered 2MF. o 2MF. 8MF. wire ftë the primary and 48 turns for the sec- 110 VOLTS oBFOET ondary. The primary is wound on one end of A. C. the coil and a space of % -inch is left before the secondary is wound on. Both of the coils are IMF wound in the same direction. The second R. F. coil (L2) is made the same as the first coil (L1). except that the primary contains 15 turns. In the aerial coil, the end of the secondary -farthest away from the primary is connected to the grid of the tube. In the second coil, the outer end of the og- primary is connected to the plate of the tube. Q 2310 The next step in building the set is to drill the panel for the condensers and rheostat. Place Connections of a simple electrolytic recttficr, which will furnish up to 90 volts "B" supply without the parts approximately in the positions shown the use of a step -up transformer. The variable resistor regulates the detector voltage to any in Fig. Q. 2311 B. The positions of the Lodes desired amount. depend on the particular apparatus employed and will have to be determined when the parts have been bought. After the panel has been drilled (A.) Yod will find the diagram of a power unit (See Figs. Q. 2311 A and B.) The parts required and these parts have been mounted on it. mount of this type in Fig. Q. 2310. Four electrolytic for the set are as follows: the other apparatus on the baseboard in the posi- rectifier jars are used, and two 30 -henry chokes One 201 A- or 199 -type tube (VI); tions shown. Fasten the binding posts either with three filter condensers comprise the filter sys- One tube socket; directly to the baseboard or to small strips of hard tem. The rectifier plates are made by cutting strips Two .0005 -mf. variable condensers (Cl, C2); rubber or bakelite mounted on the baseboard. Then of pure aluminum and lead, 2 inches wide and 5 One audio- frequency transformer, about 34 wire the set according to either diagram, Fig. Q. inches long. The aluminum plates are made of ratio (AFT); 2311 A or Fig. Q. 2311 B, as you find easiest, and !e -inch extra pure or No. I commercial stock; One crystal detector (CE); check every connection. The connections to the you can obtain this from any good metal dealer audio -frequency transformer are indicated on both or hardware company. diagrams: although it may be found necessary to Bend the plates over at a right angle, one inch reverse the connections to the secondary coil in from one end. Then hang them over the tops of order to get the best results. the cells, which consist of four pint mason jars. The values of the "A" and "B" batteries de- Make the electrolyte by dissolving as much pri- pend on the type of tube used. If a 201A is mary (acid) ammonium phosphate as possible in employed, the "A" battery must be a 6 -volt storage two quarts of distilled water. Add crystals until battery; while, if a 199 is used, three dry cells there is an excess which will not dissolve. Then connected in series will be sufficient. To put these pour off the liquid and place it in the jars. Next batteries in series, connect the center terminal of insert the aluminum and lead plates into the solu- the first battery to the outer terminal of the sec- tion and connect them as shown in diagram Q. 2310. ond. Then connect the center terminal of this bat - Before using the "B" power unit, the plates ery to the outer terminal of the third battery aml must be "formed." Connect a 25 -watt electric - the two remaining terminals to the set. The cen- light bulb across the rectifier, in place of the ter terminal of each cell is the positive ( " + ") first 2 -mf. condenser, and leave the rest of the and the outer one is the negative ( " -") apparatus disconnected. This will place the bulb The "B" battery should have a voltage between across the rectifier and will supply the necessary 45 and 90, for either type of tube, and since the load. Next, connect the input or alternating cur- current consumption is rather low, the small dry - rent wires to the electric -light line and let the cell batteries can be used. unit run for about 5 or 6 hours. This will be sufficient to "form" the plates and you can con- nect the condensers and chokes as shown in the Operation diagram. High -voltage condensers are not required The set is now ready for operation. Adjust the here. rheostat R1 until the tube lights up with its The output of the power unit will supply about This one -tube reflex circuit furnishes the max- normal brilliancy; in a 20IA tube, this will be quite 90 to 100 volts, depending on the resistance of imum amplification available without making a bright, while only a dull red glow will be noticed the choke coils. This is usually too great for the "blooper." (Continued on page 505) detector tube, so that a variable resistor (a regular 100,000 -ohm carbon -type) is provided to reduce this voltage to the correct value. A 1 -mf. con- denser is also connected between the detector tap and the "B-" terminal of the unit, to keep ------12" ,. the output steady and by -pass any stray radio - -r- frequency currents. A- A+ B- B+ PHONES .001 MF In order to obtain satisfactory results with an electrolytic "B" power unit, you must use pure 44 a metal for the aluminum electrode and chemically AERIAL pure ammonium phosphate for the electrolyte. Also use only distilled water, to be sure that it is pure. : By pouring a layer of mineral oil over the sur- O face of the electrolyte. evaporation will be re- C FIDP =_ S duced considerably; and this will also prevent sparking at the surface of the liquid to some ex- 1 - tent. If the sparking is excessive, insulate the tops of the aluminum electrodes by placing rubber tubes over them or by coating them with celluloid 8' dissolved in acetone. e SIMPLE ONE -TUBE SET mod IN. (2311) Mr. M. T. Lynch, Portland, :tlaine, ' writes: F AFT (Q.) "I am a beginner in radio and, although I have constructed several crystal sets, I have NM never attempted to build a tube set. I have been ¡ Cl: m: : : a reader of your publication for almost a year, so aa m .= r. r. I .1 I am more or less familiar with the terms used in . radio. I have looked over all the back issues that . i - VUUUllIIIIIEIMM///p/p// I have on hand, but I do not find a suitable set II®Q U///F for my purpose. The receiver that I desire to W®Il! EMI= build is one using a single tube. I do not like to make a set that would interfere with my neigh- bors, so I do not want a regenerative receiver: I Q23116 want to get the greatest efficiency, though. Will you give me the diagram and specifications of a The single -tube reflex circuit of the diagram above is shown here in pictorial form; the simplicity suitable set ?" of the hook -up can be seen. The crystal detector may be of any type preferred; a Carborundum (A.) We are printing the diagram of a single - unit gives excellent results and requires little adjustment. This unit works with phones only; tube reflex set, using a crystal detector, herewith. but an amplifier such as the "Extension" may be added to operate a loud speaker. www.americanradiohistory.com Radio News for November, 1928 463 WONDERFUL RADIO! Super- Eight -100% Electric 8 TUBES- SINGLE DIAL Coast -to -Coast Shipped Direct from our Factory on 30 Days FreeTrial [ Battery or Electric I Now comes Metro's latest achievement -the world's greatest electric radio set-a powerful long distance eight tube receiver-clearness of tone that is astound- ing-ultra-selective--a set that expert radio engineers have pronounced as the ultimate for all around perfection. And to prove our claims, we will send this marvelous set to you direct from our factory on 30 days' free trial. Test it to your heart's content. Compare its quality, beauty and price with any other radio on the market, and decide to keep it only after you are atisfied that the new 1929 Metrodyne super -eight is the peer ut them all. etrodyne SUPER-EIGHT ELECTRIC Save One -Half -Low Price a Big Feature! You will be amazed at the low price of these wonder- Georgenns console with newest type, built -in sonorous loud speaker that reproduces the emir, range of vocal and instrnme -dal music. ful sets, in the console or table cabinet. Our low cost of distribution Amazingly clear and distinct. Lew, direct- from -factory price on direct from our factory enables us to save you about half their reg- 30 DAYS' FREE TRIAL! ular value. Never before in radio history have you been offered such sets at such low prices. And we are so sure of their quality, beauty and performance pleasing you that we do not hesitate to let you try one for 30 days before deciding to keep or return it. AGENTS and DEALERS The 1929 Super -Eight line offers great money staking opportunities. Nothing SUPER QUALITY THROUGHOUT ! like them for high quality- nothing near them in price. Let us prove this by Eight powerful tubes. Highest quality low loss parts. Illuminated shipping you a single dial. Positive switch control-simply turn a knob and it's on. Select your stations with accuracy at any desired volume. Beauty of Demonstration set on 30 days' free trial tone that cannot he surpassed. Console and table cabinets are hand- Test it- compare it- demonstrate it to prospective radio buyers. Get our lib- somely grained genuine walnut, hand rubbed, in two -tone effect - eral discounts -exclusive territory -newspaper and billboard advertising artistically carved trimmings. All metal parts finished in two -tone offer that will help you sell Metrodyne radios quickly. Sold. Seeing is believing. You will be the judge. We are one of the pioneers of radio. t e METRODYNE success of Metrodyne sets is due to our Ii - end 30 days' free trial offer, which giv_s RADIO SETS you the opportunity of trying before burin;. Are Equipped For Thousands of Metrodymes have been bou.-.t on our liberal free trial basis. We will s 1 BATTERY or YOU hundreds f letters from owner: . ELECTRIC acclaim the Metrodyne as the greatest r set in the world. A postal, letter or t 11, OPERATION pon brings complete information. to - ntls. whole -ale price and our lib , SJ days' free trial offer -WRITE TODAY: a METRO ELETRIC COMPANY 2161 -71 N. California Ave., Dept. 12 Chicago, Illinois Gentlemen: Send me full particulars about Metro! ce Send Coupon Today for Our Super -Eight sets and your 30 days' free trial offer 30 Days' Free Trial Offer -..i Name ...- METRO ELECTRIC COMPANY dc'dress- 2161 -71 N. California Ave. Dept. 12 Chicago, Illinois If you are interested in .4GE.1TS prep- osition, place an "S" in Ute squaw y Ple.nsr .cav c a w il in RADIO NEWS www.americanradiohistory.com 466 Radio News for November, 1928 How to Make Your Own Television Receiver (Continued from page 425) hook -up, incidentally, it is a good idea to To receive the .Jenkins radio movies, on shunt the glow -lamp by a 0- 10,000 -ohm 46.7 ureters, you can use this sane ap- Variable resistor; this resistor should be so paratus with the disc speeded up to 900 set that the tube lights nicely when there is r.p.m. These "movies" are black and white no incoming signal. The 171A draws about silhouettes, usually of a little girl bouncing 20 milliamperes, which is the normal load a ball, or playing with a clog. limit of the glow -lamp; so the combination Next month we will publish more tele- works out very happily. vision "dope." Meanwhile, try your luck with this receiver; you will have a lot of TRY YOUR LUCK fun with it. Remember that television as we have it to -day is very crude. Do not Fig. 4 expect perfect images, and do not forget that television on 3,000 cycles was, until only very recently, held impossible alto- gether. Experiment with the 0 Drilling layout of the 24 -inch disc used. .4 full -size template accom- panies the blueprints -if you wish to try your luck making your own. 1 Look for the neon tube and the motor's speed and try different output { á arrangements. Try putting an t ordinary reading glass in front of the images, as shown in the ,p . see if // cover illustration, and you can magnify then[. Experiment, and on top of all let us know what results you have obtained. \ READERS will find interest and probable profit in the article, "Ho w to Build the 'S & I' Television Receiver," in the November issue of SCIENCE AND INVENTION RADIO / TUBES Magazine. This receiver may be readily built upon a fan motor, like the experimental set -up described in RADIO NEWS for September; and employs a very simple, but ingenious, visual ( "stroboscopic ") method of determining its speed and obtaining WHENWHEN you look inside of your synchronism. be sure you see the monogram "C" smiling up at you on the top of each radio tube. Televentures, Telewitticisms and the Televocabulary Thirteen years of experience and tireless research, combined with a (Continued (rota page 419) guarantee against mechanical and within a generation to broadcast to a whole Will both he "televisors "? And if not, which? electrical defect, stand behind this nation such sights as a Reinhardt 'Miracle' "Television" is a word on which the lan- simple monogram. or a tennis match. The optimistic American guage sharps look askance; like "automo- it is a hybrid Latin and half Tube quality has re- regards the surmounting of obstacles as the bile," -half Cunningham very essence of invention, and rightly. One Greek -and the public has even less Latin leadership and sulted in national has but to read the Federal 'Trade Commis- than the Bard of Avon, and no Greek. The public approval, two assets we sion's examination of radio patent mo- editor of RAnlo NEWS, before the days of zealously guard, and is your assur- nopolies to learn of the romance that lies broadcasting; coined "television," and sug- ance of faultless modern reception. in vaulting over technical obstacles -of for- gested for the apparatus "telephot," which I tunes paid to young engineers who made it is a better word from the dictionary stand- possible for a farmer in carpet slippers to point than "televisor." Will we use "phots" Never use old tubes enjoy the Philharmonic Orchestra better or "visors"? An English writer has hinted with new ones -use a in Hall. of "teleopsis" and "teleoppers," to be short- new tubes throughout than in hard -boiled shirt Carnegie To an inventor of imagination the difficul- ened into "'oppers "; but this seems to lack ties that now beset the commercial realiza- the necessary seriousness to convince. will be the of the operators? E. T. CUNNINGHAM, INC. tion of television are glittering opportuni- What title We have "radiotricians" as specialized elec- New York Chicago ties, and it is in that spirit that they will be conquered." tricians: we will need a word of the weight San Francisco of "televisticians.," which may do for the WHAT OF Manufactured and sold under rights, patents TILE DICTIONARY? present. But a "'visionary engineer" seems and inventions owned and /or controlled by Radio Corporation of America. With the vocabulary of even radio broad- impractical. casting quite out of the hands of the engi- Television transmissions require modulat- neering profession, what is the puzzled ing frequencies, increasing with the size and maker of dictionaries to do about the new detail of the image. While small figures words which the art of television will re- suitable to the experimental receivers of the quire? The "glow lamp" and "scanning day are being reproduced front audio fre- disc" may be soon used only in the past quencies, the larger images of tomorrow will tense; but what shall we call the apparatus require wider bands and special amplifiers. required for the transmission and reception? These will be specially designated; "image- Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 467 The broadcast of the Army -Navy game last year toas enjoyed by hin- dredojthousands Phillips Carlin of fans all over the broadcasting country. at one of the big football games. The Big Game Conies Over__ BETTER CLEARER MILLIONS of enthusiastic football fans are It combines remarkable shielding proper- listening this fall to the play by play broad- ties, high electrical conductivity, great strength casts of America's greatest games. They are and extreme lightness. experiencing almost as keen enjoyment as if Examine the set you contemplate buying. they were sitting in the stands. The voice of If it is Aluminum equipped you may rest as- the announcer comes to them clearly and dis- sured that the manufacturer has done every- tinctly because their receiving sets are Alumi- thing in his power to give you the finest pos- num equipped. sible reception. Leading radio manufacturers are using Alu- And if you are building, a receiving set use minum extensively for shielding, for conden- Aluminum for finest results. ser blades and frames, for chasses, sub -panels, front panels and for many other parts -be- We will gladly send you the booklet,' Alumi- cause Aluminum so ideally meets the varied num For Radio," which explains the varied conditions that radio design presents. radio uses to which Aluminum is adapted. ALUMINUM COMPANY OF AMERICA ALUMINUM IN EVERY COMMERCIAL FORM 2467 Oliver Building "® Offices in 19 Principal Pittsburgh, Pa. ALUMINUM American Cities C >V ALUMINUM `?he mark ofQuo /ity in Rodio Please say you saw it in RADIO NEWS www.americanradiohistory.com 4Gì; Radio News for November, 1928 frequencies" seems most logical, but the WRN T's television inauguration, perhaps "I. F." of the superheterodyne is already had in mind all this and more, when he The New Victoreen too well established. Perhaps we shall have stated that he could not refrain from beat- "T. F." amplifiers for television frequencies. ing the newspaper columnists at their own A. C. Circuit It is too early to start on the task of game when he suggested that hereafter, we standardizing the vocabulary; but we must will call an inventor, not "visionary," lint have an eye to the future and see that the rather, "televisionary." Also, that we will Is the Outstanding newcomer in radio is not saddled with not talk of a beautiful "vista" any longer, names that will be a burden in days to but it will, of course, surely be a "tele- Success of the Year come. We must have, O philosophers, a new vista"; and, that certain females who are "teleology." now called "perfect visions," are, of course, Mr. H. Gernsback, editor of this publi- to become "perfect televisions"; and that cation, while addressing an audience at the finally, there will, of course, be a great New York University, at the occasion of many "telewisecracks." "Comforts of Home" Vital improvements in Victoreen R. F. Transformers, together with changes in !RAM VQCfb`YDEa$ the circuit itself, have still further per- fected and simplified a "Super" which for years has had no superior. Go6ght-r; :l. The New Victoreen is simply mar- ---';, velous. Here you have A. C. operation at its best. Tone quality such as you tN'NNS -... have never heard before -selectivity such as you never dreamed to be possible -simplicity of assembly developed to the point where anyone can construct a set which is as nearly perfect as human ingenuity has been able to devise. The heart of this new Victoreen cir- cuit is of course the world- famous Victoreen R. F. Transformer -greatly improved in efficiency, with binding TELEVISEN posts located for maximum convenience in wiring. Each transformer is individ- ually tuned to a precision of less than 1/3 of one per cent by the Victoreen patented method. These new Transformers, together with the other Victoreen components which are used in this remarkable set, are literally years ahead of their time. To get the results which only Victoreen gives, either build, or have built for you, a Victoreen Super. BLUE PRINT FREE together with full constructional details. Write for it today. Victoreen "B" Power Supply -Clive Weed in New York Evening World Radio fans will sec that the mnnbcr of sound reproducers is somewhat too large; and the televisi- phooe will probably be of a later model. gut the idea is clever, even though the "Television" is one -I'd. "C" Voltage Depends on "B" Voltage Supplies 45, 90, 180 and 450 volts, using batteries are used to supply teries run down with usage, the "C" battery a UX 210 or 250 in the last stage. Contains WHEN "B" two voltage regulator tubes so that the 90 and the plate current for a receiver, listen- will last for the entire life of the battery - 180 volt taps are' supplied with a constant volt to watch the voltage of without any appreciable loss of voltage. potential. It is the last word in "B" supply. ers are cautioned For the most satisfactory results you must the batteries and to discard them when the This means that when the "B" batteries have it. voltage of each 45-volt block runs clown are new, the proper grid bias is being used FREE BLUE PRINT, with list of parts to about 34 volts, or when that of each . for best results; but just as soon as the and complete assembly instructions, will to about 17 "B" battery voltage begins to decrease, the be sent upon request. 22/ -volt block runs down volts. grid -bias voltage is greater than is needed W. Company Fans who employ- "B" batteries therefore for the lowered plate voltage. The George Walker at regular intervals to In such cases, if the grid -bias voltage is Victoreen Radio Parts usually test them Merchandisers of determine whether the batteries are still reduced in proportion, as determined by- 2825 Chester Ave., Cleveland, Ohio good for further service. consulting the tables showing the proper A matter of vital importance which is plate voltage- grid -bias voltage character- often overlooked, however, is that of pro- istics of the tube. the amplifying efficiency viding a proper relation between the grid - of the tube can be maintained at a high bias voltage and the plate voltage. level in spite of lowered plate voltage front Quality Radio Partsi It is generally known that, while "B" bat - the "B" batteries. Please say you saw it in. R.4DIO NEWS www.americanradiohistory.com Radio News for November, 1928 Now-, a e ovr dfír 4;:f ear as a ^-1.uzth Ma rvelous11i'ew ;!,. ,,,,1,,,",. GROUND .4 ERIALØ Sub -Aerial Get Amazing Distance- Greater Endorsed by Experts Volume and Finer Selectivity May Stti. 192S 'I am very glad to state that after testing many Aerials in my Laboratory Without Distortion I lind your Su b-Aerial is the bust for clarity of tone and elimination of static also for greater Volume and Why go on listening to terrible static and other madden- caeetivity. Your Sub -Aerial will fill a long-felt ing outside noises? Now you can get the real music your want among the Radio Fans." present Radio is capable of giving, by hooking your set on A. R. Johnson, practically waves with Radio to the clear, static free ground Engineer Sub -Aerial. The air is always full of static and your over- Chicago. May 9th. 192S "Received my Sub- Aerial and it has head aerial picks it up and brings it to your speaker. So botat Installed as Per directions. We are more than satisfied W theresults. why stay in the air -when you can use the whole earth The tune Is marvelously clear without as a static and noise filter with Sub -Aerial? static interruptions. We would not changing hack to an outdoor aensblerrial under any circumstances. SUB -AERIAL is a scientific, proven system of taking M. H. Grey. 1416 Junetray Terrace. the radio waves from the ground, where they are filtered practically free of static. It brings these filtered waves to your radio set clear of static and interference common with overhead aerials. The result is positively clear reception, remarkable selectivity and greatly increased volume. The overhead aerial is a thing of the past because it is the weak link in radio. SUB- AERIAL has replaced overhead aerials because SUB -AERIAL is 100°,ó efficient. How can you get good reception without one? Low Original Cost -No Upkeep Cost SUB -AERIAL costs no more than an overhead or loop aerial and less than many. Its first cost is the only one. SUB -AERIAL is permanent. No trouble -no hard work, or risking your neck on roofs. 25 Year Guarantee SUB -AERIAL is guaranteed against any defects in workmanship or material and against deterioration for 25 years. Any SUB -AERIAL which has been installed according to directions and proves defective or deteriorates within 25 years, will be replaced free of charge; and also we will pay $1.00 for installing any such new replacement. TRY IT FREE! We know so well the surprising results you'll get that we'll let you put in a Sub -Aerial entirely at our Risk. You be the Judge. Don't take down your overhead Aerial. Pick a summer night when static and noise interference on your old Aerial are "Just Terrible." If Sub -Aerial doesn't Sell Itself to You Right Then on Performance- Can Be Installed you needn't pay us a cent. Send for "all the Dope on Sub -Aerial." You'll be surprised. Do it NOW. in a Few Minutes UNDERGROUND AERIAL SYSTEMS St. Clair Bldg., Dept. P Undergroune Aerial Systems, Dept. 9-P Corner St. Clair and Erie Sts., Chicago, III. St. Clair :aids., cor. St. Clair and Erie Sts., Chicago, Ill. Send me complete information on Sub -Aerial, Proof and Free Trial Offer. No obligation. Name._ GroundOutStatic ______Address ',itiv,Sl16AERIAI Please say you saw it in RADIO NEWS www.americanradiohistory.com 470 Radio News for November, 1928 Follow the Lead of the L E A D I N G PERHAPS IT WAS TELEVISION YOU HEARD MANUFACTURERS Program of radio entertainment from the Providence Journal of August 5: "9:35 p. ni. Baseball scores. 's Lusky 4 oMaHwpluli. PAY MORE EAL nn nn m wwkwk." What is the use of trying to eliminate static when they arc GET MORE actually broadcasting it this year! We sur- with render right now. -Chester H. Page. ATTENTION, BETTER BUSINESS BUREAU DUBILIER Suspicions of the Blue Sky bureau ver, SOCKET POWER aroused by advertisement of "3 -foot double Cox speaker kit," in Hampton- 33"right'.s CONDENSERS catalog. Mike, the fearless investigator, went out sleuthing, and detected this slip- After exhaustive tests, the engin- pery speaker eers endeavoring to sell the Wheat- of the leading manufactur- stone Bridge to a couple of newly -arrived ers, have standardized on Dubi- THE ORPHAN OF THE STORM and innocent tubes. -Raoul Esca Hie r. lier Condensers. They pay more Directions enclosed with tithes by S. S. for them -- but they have the Kresge Co.: "It is essential that a grid bat- assurance tery he used, otherwise the windings of the that their loud speaker will probably be TURNED out" sets are go. Oh, Mr. Tube, have pity on a poor old ing to stay speaker, who has no other place to lay his sold and diaphragm, and don't drive him out into the they know cold.-A non yaaoas. thattheam- ple factor of safety BLAME THOSE ELECTRIC EELS! Advice to a set owner whose battery runs means long down too life. They soon, from the Sydney San of Jul- 3: "It is possible there May he a par- can't afford tial short -circuit in the SEA." We think that to take a Type PL-666 and PL667 are a socket -power unit will be cheaper than a chance and standard equipment on high diver's suit, in that case. What do you say? voltage AmerTran. Samson, save a few Thordarson and other power IF SINNERS ENTICE THEE, -Sid H. Cox, (Australia). cents. And packsspecifyingUX 281 or CX CONSENT THOU - 381 type rectifier tubes. Type Perils which neither can PL-666.... 2 mfd. 1000 volts - to radio parts are exposed- $6.50: Type PL-667-4 mfd- ntorally and otherwise -revealed by W. C. you! 1000 volts $11.00. -Price Braun's catalog: "The slightest inaccuracy. You can forget the Condensers - allows disastrous URGES to rush through to if they are Dubiliers. the tubes." We think the R.M.A. should es- tablish a Big Brothers' league to keep young and innocent tubes from imitating the Monk Dubilier of Siberia.- Rowlind Bohstedt. LIGHT SOCKET AERIAL GO TO THE ANT, THOU SLUGGARD If it does :Advice of Solomon put to practical use by new invention advertised in the Boston. Post not work of .Izane 15: "Johnson ANTOscsTic charger, on your $5." We suppose that the power of the in- dustrious ants charges the battery; but we set -your would have to catch an awful lot of them. money back The charger could he taken with a portable DOCTOR, WHEREFORE THESE TEARS? set to the next picnic, though. -Robert H. And we mean it! If it Court procedure for compulsory licensing Lefkovich. doesn't give you smooth recep- under Marconi patents of Loewe multiple- tion, reduce static and interfer- tube sets elicits the fact, as reported by the ence and give you plenty of London Star, that some of these tubes con- volume dealer will give tain "two LAMENTS," making it possible to the you "get every European station to Moscow for your money back within 5 days. a total price of £4 17s wholesale." Why Uses no current. Just attach to the lamentation -unless it is for more con- your set and plug in to a conven- tinents to coriqucr ? -A. M. Gibbs (Eng- ient light socket. Price $1.50. land). Write for free booklet OH, THOSE POWER -HOUSE CHORDS! REMODELED WHILE YOU WAIT Affirmative reply by the New York Tinges Boon offered to the wearied experimenter Dubilier of July 1 to the query, "Can I put a by Hamilton -Carr s latest: "Sterling Power DvNAMO speaker in series with an ordinary OtTFIT traensfornaer...$2.94." We have sent C O N D E N S E R cone' raises the question whether or not for this and will set it to work changing the CORPORATION this combination, like Charity, will not begin old five -tuber into an A.C. screen -grid to hum? As soon as we have a spare mo- superhet with television attachment. While 4377 BRONX BLVD. NEW YORK ment, however, we may try it out with our one is transforming the outfit, the ,job might M. G. C. John Heberger, 8AEC. as well be an thorough one.-Ted E. Jocelyn. Please say you saw it in RADIO N E www.americanradiohistory.com Radio Nest's for .\ nz.cinbcr, 1928 WHOLE' SALE PRICES fôrDeaiers, Cornmuniti Sei-Builders, General RepÉrmen and Acids! Be sure to get this great 144 -page book with net prices to the radio trade. Radio Specialty Company is radio's oldest radio parts mail order house in the country, and the new confidential prices on standard radio merchandise are the lowest of any radio house. We are ready now to appoint additional agents in all parts of the country. If you are contemplating making big money in radio merchandise, be sure to get in touch with us at once. devisioll is here! Radio Specialty, as usual, is first with all new things. Send at once for free booklet for lowest prices on all tele- vision parts which have been put on the market so far. (If you have Catalog No. 18, just ask for the Television Supplement.) ?1eìi75OOKUpS 500 I LLU STRATIONS from 92adios Oldest tail OrderJlouse i We are the oldest established, exclusive radio mail order house in the country. teous service. We carry a larger variety of radio parts, radio instruments, All orders arc positively shipped within twenty-four hours; quick, prompt, cour- accessories and radio findings than any other radio house in the country. You will find in Catalog No. 18 the largest assortment of radio merchandise in this country. Radio Specialty carries more radio parts and radio material than any other house in the country. You will find in this catalog positively the largest variety of radio merchandise. If you re in need of certain small radio parts that other radio and mail order houses do not bother to carry get the Rasco Catalog and you will find the small parts there. anything from a screw to copper ribbon, tele. iE phone diaphragms, as well as thousands of other small radio findings. Just to mention a few: "RpSCOr`has Lugs. nuts, jacks, plugs, all kinds of knobs, cords, panels, screws, sliders, washers, selenium, tinfoil, switches. rystabs. cap nuts, Litz wire, cord tips, brass rods, resistances, binding posts, switch parts, carbon balls, switch points, lock washers, carbon grains, ground clamps, metal pointers. insulated tubing, low melting metal, antenna connectors, as well as thousands ANYTHING of other articles. We carry the Largest Variety of Small Radio Parts in IN RADIO the World, BUT We also carry All Standard Radio Merchandise. 98W PARK PLACE, NEW YORK P l e a s e c. u r r n n s a m ti .1 IJ 1 1l .A' F_ f ls www.americanradiohistory.com 472 Radio News for November, 1928 THE MONDAY -MORNING SIX Household convenience offered be Gar- dener cf 1Vhite, Detroit, Mich.: "Crystal ¡Raytheonst-- Electric Washer, $120. TIIBES and SPEAKER priced extra." The Lux program is said to be extraordinarily effective on this instru- K111,oLdnIP ment, which should indeed make washday a pleasure. But we hope that the static will not fray our collars or take the buttons off PARTS IN CONSERVATORY STYLE our shirts. J. S. Bevan. Floricultural fashion note in Sears, Roe- buck tí Co.'s catalog for the coming season: "Heavy PorrEO transformers." Radio fans who are interested in decorative effects will jump at this chance to decorate the music room with transformers, instead of the old style palms and rubber plants.Rowlind Bohstedt. RICHARD IS AN R.E. The new short -wave receiver described in the Boston Globe of August 5 is evidently ,1 operated by a mechanical man: "Tuning Ir,' with the metallic DICK is accomplished by angular displacement." We understood that i!ìd Mike is the iron man who steers ships: but (' st. t it seems that Richard is the radio expert of A SUNBURNT SCIENTIST'S THEORY the famih. -FI. .1. Albin. Explanation of the "skip-distance" effect in the S,ydnerl herald of June 29: "The ionisation is caused by the ULTRA-VIOLENT IF vos, sec any humorous misprints about Radio light transmitted from the sun." Well, if in the press, dip them on t and send then, to RADIOTICS. e/o RADIO Saws; send also the we were a little hit of a wave, only a few TWO PIONEER heading of the page, shooing name and date of meters long, we'd steer quite clear of the publication of the paper or magazine. .add a few Ileaviside layer, where such dangerous trav- humorous words of comment; the best contribu- TELEVISION eling conditions prevail.-Robert F. Willie tions teill be printed, in case two or more send in (Australia). the same R.DIOT!C. For each one printed here, ACCESSORIES $1.00 will be paid. The Raytheon Laborator- Radio As an Advertising Force ies invite correspondence D)ES radio advertising pay? Some ceipt $2,650,000; an increase in attend - from both engineers and radio advertisers, like 3I r. Henry ance of amateurs in regard to these 312% and in receipts of 539!,. Field, of Shenandoah, Iowa, have shown that "'These are the facts, Mr. Rickard ! They two accessories now in the most direct kind of advertising floes pay, tell an altogether different story. They successful operation. if it is suited to its prospective customers. show that fighting came into its own with Other advertisers who have used more in- radio broadcasting. That both gate receipts Raytheon Kino -Lamp is direct methods have evidently found that and attendance reached their highest point the first television- recep- their sales sheets showed very encouraging at the peak of radio broadcasting ... Radio tion tube developed to trends. But what of the business which has raised pugilism to the dignity of a great work on all systems. looks upon radio as a direct competitor- national sport with a new following of mil- the great industry which entertains the pub- lions of men and women. Think it over. Raytheon Foto -Cell, an lic in person, and must therefore regard as Mr. Rickard. It may be that you even owe extra sensitive broadcast- a disturbing influence whatever makes the a debt of gratitude to the thirty million men ing tube, is supplied in fireside armchair more attractive at the close and women -the `Ladies and Gentlemen of either hard vacuum or of the day? the Radio Audience.'" Here is a most pertinent putting of the The detailed figures which accompany the gas -filled types. case by a third party in interest -a radio advertisement only further exemplify the merchant to whom radio is but an incidental argument; but to date, 3Ir. Rickard's come- RAYTHEON MFG. CO. item, though a large one. back has not been recorded. At any rate, if This advertisement was published by radio advertising Kendall Square Bldg., Cambridge, Mass. entertains the stay -at- Bloomingdale's, a concern operating a large homes, it certainly coaxes no small number department store on the upper east silk of out and into the throng of cash customers. New York City, as well as stores in Brook- lyn, N. Y., and Newark, N. J., and takes the finnl of an open letter to a well -known fig- IN STRICT CONFIDENCE ure in the great industry of selling ringside VISITOR : "And what became of the radio seats: set you had?" "Think it over, 3Ir. Rickard! After the HOSTESS: "Oh, it didn't work right; so I Tunney- Heeney fight the newspapers voted got rid of it." you as saying, `I blame much of the failure VISITOR: "I couldn't meet my payments to have out a paying crowd on the radio. It either: " -Rd core! Piranian. helped kill my business.' Are you absolutely certain that your loss is clue to radio broad- casting: As one of the leading radio stores THE ULTIMATE ULTIMO in this country, we feel it to be our duty SaiITtI: "If prizes were given for the toward the millions of radio owners to point laziest anon, Biggs would get the fur-lined out a few interesting facts in the matter. bathtub." fRaytheoif. "Before broadcasting -the biggest attend- JONES: "IS Ile So la'Ly ?" ance was 40.000, the biggest gate receipt SMITII: "Is he? He's so lazy, he'd rather Foto-Cell $450,000; after broadcasting -the biggest listen to a bedtime story than turn the attendance was 165,000, the biggest gate re- dial I "- Jloltie Zacharias. Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 473 t- (Chemistry p..Vs .4. to success! Some people measure success in terms of money and others in degree of knowledge and culture. Chemistry is the one uncrowded profession today that offers both. America, always a land of amazing opportunities, is especially so now in the field of applied Chemistry. In- - dustries have developed within eight years more rapidly than the output of trained men to conduct them. Every big industry needs chemists and there is a real demand for them imnlcdi mtcly. Earn a Bigger Salary from now on Good Chemists Command High Salaries Not only are there boundless opportunities for amassing wealth in Chemistry, but the profession affords congenial employment at good salaries to hundreds of thousands who merely follow out its present applications. These applications are innumerable. touching intimately Just a Few Letters in the The work of the chemist From Students Who llave every business and every product world. Taken This Course can hardly be called work at all. It is the keenest and most enjoyable You will probably be pleased to kind of pleasure. The clays in a chemical laboratory are filled with learn one of the lessons gave me thrilling and delightful experimentation, with the alluring prospect of a an idea to turn niy chemical knowledge to profitable account. discovery that may spell Fortune always at hand to spur your enthusiasm. I am now staking a varnish and paint which undersells the other type products by $2.60 a gallon, in some cases more. Have been You can make yourself independent for life by un- receiving gallon orders from paint. 's during past week which has netted the a profit of 512.50 for earthing one of Chemistry's undiscovered Secrets my "spare-time chemical indus- try." \fang thanks for your of used to fire your imagina- training thus far. Do you remember how the tales pirate gold J. J. KELLY tion and slake you want to sail. the uncharted seas in search of treasure and I am but half -way through your adventure? And then you would regret that such things were no longer course and am certain that I have done. is are done and every clay on saved my Company molly antes But that a mistake. They -today -not the cost of the course and raised desert islands, hut in the chemical laboratories throughout your own coun- myself in t he shareholders' estima- tion. The knowledge obtained has try. Quietly, systematically, the chemist works. His work is difficult, but its immediate prao leal application more adventurous than the blood- curdling deeds of the Spanish Main. In- tuul I do not hesitate in saying T. O'CONOR SLOANE, your course and the personal at- A. B.,A. M .,L L. D., P h. D. stead of meeting an early and violent death on some forgotten shore, he tention you give Is im.luable to gathers wealth and honor through his valuable contributions to humanity. the practical man In any business 'Microchemistry plays a part. You N otedIust ructor,Lectur- Alfred Nobel. the Swedish chemist who invented dynamite, made so many millions that may use this letter and my name the income alone from his bequests provides five $40,000 prizes every year for the advance- and address to the furtherance of er and Author. Form- ment of science and peace. Hernian Frasch, who showed how to extract sulphur, built your good work. erly Treasurer Ameri- tip a huge fortune. C. M. hall, the chemist who discovered how to manufacture aluminum, JOHN WALTER. 1'. who devised a can Chemical Society made millions through this discovery. G. Cottrell. valuable process for I have not written since r re- recovering the waste front flue gases, Jantes Coyle)... who showed bow to save enormous ceived the big yet. I can still say and a practical chemist losses in steel manufacture. L. H. Baekeland, who invented Bakelite-these are only a that it far exceeded my anticipa- with many. well -known few of the men to whom fortunes have come through their chemical achievements. tions. Since I have been studying with your school I have been ap- achievements to his YOU CAN LEARN AT HOME chemist credit. Not only has ('oat Co.. all the coal and To qualify for this remarkable calling requires specialized training. Formerly it was ssh by proximate analysis. The Dr. Sloane taught chem- necessary to attend a university for several years to acquire that training, but thanks lessons are helping me wonder- istry for years but he highly perfected and thorough of instruction, now home, fully. and the interesting way in to our system ;'ou can stay at which they are written makes me was for many years en- keep your position. and let us educate you in Chemistry during your spare time. Even wait patiently for each lesson. with only common schooling you can take our course and equip yourself for immediate attai.ais COUZENS. gaged in commercial practical work in a chemical laboratory. chemistry work. EASY MONTHLY PAYMENTS EXPERIMENTAL EQUIPMENT FURNISHED You don't have to haveTeven the small price of the course to start. You can pay for TO EVERY STUDENT it in small monthly amounts -so small that you won't feel them. The cost of the course is very- low, and includes everything, even the chemistry outfit -there are no extras to we give to every student, without additional charge, his chemical buy with our course. Our plan of monthly payments places a chemical education within equipment, including fifty -two pieces of laborntmy apparatus the reach of everyone. and supplies, and fifty -two different chemicals and reagents. These comprise the apparatus and chemicals used for the experimental MAIL THE COUPON FOR FREE BOOK work of the course. The fitted heavy wooden box serves not only Your name and address on the coupon will bring you by return mail our interesting free as a case for the outfit. but also as a useful laboratory accessory book. "Ol'l'ORTUNITIES FOR CHEMISTS." and full particulars about the course for performing countless experiments. and what it will to for von. You owe it to yourself to get this book. Send the coupon right now while it is fresh in your mind. Or just write your name and address on a postal and mail to us. But whatever you do, act today. CHEMICAL INSTITUTE OF NEW YORK, INC. Home Extension Division 11 16 -18 -R -East 30th Street, New York, N. Y. SEIZE THIS OPPORTUNITY COUPON NOW ! -MAIL Please send me at once, without any obligation on my part. your free book, "Opportunities for Chemists." and full particulars about the Experimental Equipment given to Chemical Institute of New York, Inc. every student. Also please tell nie about your plan of payment Home Extension Division 1l NAME 16 -18 -R -East 30th Street New York, N. Y. ADDRESS CITY STATE R- N -I1 -2S /' s,' s r r , n u .i t. ,, i i u R.11)1O . \'EII'.4' www.americanradiohistory.com 474 Radio News for November, 1928 quite oscillatory. Let us he thankful that Radio "Bugs" it does not pass too close to our humble residence and receiving station. Just one HE amazingly lifelike figures which our more example, and this department closes 1 ingenious readers macle out of the eon - again with acknowledgements to all its LONGER ventional figures of the schematic circuit coadjutors. arc not without honor abroad. European "Short Waves from Java on the l'eri- magazines are following the example of dyne" is the humorous title which henry LIFE RADIO NEWS; and from our contemporary, Newhoff, of Chicago, applies to this ingeni- Radiowelt of Vienna (Austria) we take ous sketch of a combined coffee pot and Perid-ne stage. We don't know ,just how A i /_V C v`4 RADIO TUBES these two fine specimens, which show that P O N O P N C E D humor, like radio, is international. 6 1E - CO "Die Wcllenwalzer" -the dance of the waves, is expressive; even though the lady's skirt is. unusual, it strongly evidences that Racli®Tubes one touch of jazz makes the whole world kin: WHEN you install a set of CeCo Tubes in. your radio, you immediately notice practical the idea is; but a milk ( ?) shaker makes a good shield, according to our the greater clarity of reproduc- Beginner's editor, and we wait to see an entry of this kind in the Monthly Construc- tion -the increased sensitivity tion Feature. and the better volume. If you have any more "Bugs," consult the corner druggist, or the community trouble shooter. The department of Radio But your greatest satisfac- Entomology is now a has -been, and some of "Die I_uhalbahn von Itaulinpolis" will be our friends may hint that it is a never -was. tion will come with their longer relished by all cnnuuuters on the Blank, operating life- making CeCo Dash and !!!? ßaiload; we do not specify more closely, on account of the libel laws, Advertising or Subsidies? the most economical tubes to but you will recognize this as the train which pay licenses is met by the Toonerville Trolley. I.1ilstralia, radio set owners buy, and worthy of their which are used to support "Class A" sta- slogan, "they cost no more, tions; while "Class B" stations, owned in most eases by organizations which desire ai but last longer." This is made mouthpiece for their views, are not so fa- possible partly by the ex- vored. Since the Commonwealth's postal authorities have undertaken a coordination clusive method of evacuation. of the programs and activities of the "Class A" stations, a request has been presented To avoid disappointing re- on behalf of the "B" stations for either a. share of the license revenues or the exclusive sults, make sure each socket right to accept paid advertising. In the is tubes. latter case, the virtues of the sponsored pro- equipped with CeCo grams might be fairly tried out -were it Whether for battery or A. C. not that the Australian listener must pay the bills of the preferred stations, whether operation, there's a CeCo for or not he prefers other programs. Our every radio need-including American system has still some advantages which will commend it to the listeners, even "special purpose" tubes that though there may be a few corresponding are not obtainable elsewhere. drawbacks. They are sold by leading deal- Our own "Bug" ontest closed some months back, but we take the opportunity Brightness No Guide ers everywhere. to give a couple of excellent sketches which have since reached us from Leo D. Keller, SET operators, who have been used to of Rochester, N. Y. "The Waveband Di- consider the brilliancy of tubes as a Tune in Monday evenings to rector" should be able to straighten out measure of their operating condition, en- counter a new condition with the new A.C. the nearest of the 18 Columbia the radio concert; let us hope so. The troller ear shown here should be heated -cathode tubes, such as the 227-type. Broadcasting Stations and hear The manufacturers explain that differences the musical program of the in the light emitted have nothing to do with the performance of these tubes. Only a CeCo Couriers -8 P. M. East- portion of the heating element or filament ern Time,7 P. M. Central Time. is exposed, and changes in its brilliancy at this point do not imply that the temperature below is incorrect. These tubes will stand a CeCo MANUFACTURING Co., Inc. very considerable overload on the filaments; PROVIDENCE. R. 1. E though, of course, the wise experimenter will not subject them to the test. . say y o u saw it in R.'17) I Cl AT T J{T 5 www.americanradiohistory.com Radio News for November, 1928 4/.` Television Trials (Continued from poye 439) Lest systems must be worked out Lry actual practice. Will transmission be easier, and reception clearer, on this waveband or that? e a adio xpert Which mechanical system will be most satis- factory in the long run? We may compare the state of television and its kindred arts to that of transpor- tation in 183g: it is no time as vet for standardization. The "Toot Thuutii' was a good locomotive in its da v, but railroading would have been at a sad pass if it had to be standardized on the basis of such machin- ery. So with television; it has yet a few years ahead of it in which to be perfected, and undoubtedly the final apparatus which will be used for home, as well as commer- xJ .Smifh cial, scientific and governmental reception will he as much superior to that with which I've trained hundreds of fellows at home we are now wuirking as the great passenger and freight locomotives of today exceed in their spare time forl3ig PayRadio Jobs. the "Tout Thumb" in efficiency. amazing growth is making hundreds of big -pay SPECIALIZED SYSTEMS FOIL ALL NEEDS i every year. Trained men are needed. You young, RADIO'Slobs ambitious men, starting out, who are looking around for some- It is probable that, even when television thing really good, and you older men, who aren't satisfied but money a field that is growing fast enough has become a art, are shall be a want more -here's perfected to bring success in a year or two. I have doubled, tripled, quad- Has Made 510,000 More - lung ways from stnndardizilion. The prob- In Radio rupled the salades of men in one year. My book points out the Radio. Clip the coupon. Get a copy now. Why bands which can safely say many jobs in lem- of the frequency can be "I with anything less than $50 to $250 a week when that I haace made be satisfied allotted for the purpose is one of the 810,000 mom in Ra- that's what Radio pays its good men? broadcasting is dio than I would principal ones; even if revo- have made If r bud Begin continued at old So May Opportunities-Many Making $10 lutionized, it is probable that cnulparatively- the , Job. alien I en- to $30 a Week Extra Almost at Once Iiulited lemds will be used far the television rolled with you I didn't know a volt You don't have to wait one year, two years, not even six months transmissions which will he receivable in from an ampere. I advise all to begin getting the extra money you want. I'll show you the ambitious young men to get. plans and ideas that are making $10, $20 and $30 a week extra the house. INIuch more elaborate apparatus Into Radin. There is no greater for my students -show you how to begin doing it too the first opportunit F " plans. G. W. will he used to project pictures in theatres Victor L. Osgood. month if you study hard and follow my Page, C'nnaford Ave.. 1807 21st Ave., S., Nashville, Tenn., made $935 in his spare and other places where large groups of Bronx, New York City.' time while taking my course. Earle Cummings, 18 Webster St., spectators are gathered. (Again, we need 5500 a Month Haverhill. Mass., writes: "I have made as high as $375 in one month in my spare time." No need to worry about money. a new word in the language; perhaps a When I enrolled with N. R. I,. I s :1 motorman on a trolley ear. this is the famous course that pays for itself. "televisence" will signify the gathering who Now 1 have a tine, fast growing Radio business. I have $2500 in are looking on thy screen of the televisor.) the bank and about S300 worth of Learn at Home demand Radio stock. I made It all since A great training Don't lose a minute from your job. All I Other purposes will elaborate ap- graduating test than sis months ask is part of your spare time. My prac- ago.' made paratus, operating proled ly on travel ands Richard Huller. greater' tical method of training with six big out- which are today useless even experiment, 353.5 Shem,dd Si., fits of Radio parts makes learning at for Philadelphia, Pa. Tele vision home easy, fascinating, a pleasure. Boys a 14, men up to 60 have finished my course hat which will yield frequency range $3,000 a Year now included successfully. You don't need a high capable of carrying the most detailed im- 'T cannot give school education. Many my most too much credit Television of ages, of largest sizes. quickly ran easily ant] successful graduates didn't even finish to the N. It. I. become as to whole big ans the grades. for what I Inter Radin perd For the present, the most advanced tele- been able to ,lo L tala,-. you ought That's wits visionanies are vet in the class, in Radio.] have to know kindergarten averaged about the all You Must Be Satisfied 53000 dtaen'ut fiy8- and every conceiva ire system ti ml arl'ange- it year for the m`Ina sen,lln The day you enroll I'll give you a con- ce .it.p for past to rd'Fetus. ng pietuns -there tract agreeing to refund every penny of naent must undergo careful test by engi- I ant in the Ra- :are man dio buslneas. I hcttl. /rnkiñ, rtght your money if you are not satisfied with neers other the field is it' ril:v, R;dnls ÓI,aoley"s, the lessons and instruction I give you. and experimenters; consider all the seeress 1 mime Rd1nY ohtnival u, tar due entirely to :Vexund . one men, tre methods too wide for any man or group of your training... eover,I in Vox! A. Nichols, ' nru ßalin Get This Book AT ONCE with even the most elaborate equipment that I ttaininßW ¡¡Ì Hereford. Polo. to absolutely eompiere "Rich Rewards in Radio" shows where you scientific organizations possess. 'lime hone h,iok -u1, iah the big jobs are, what they pay, what Xthenit f. experimenter will have to nibble at this dish others are making- It has started hun- I give you a home dreds of fellows on the and that, for the banquet of television dain- experimental road to bigger money ties trill present too many courses for one who thought success was laboratory. You can not for them. n 'ARD$ Ii Get digestion. design and build loo circuita 'tRi copy. Not the slightest RRa01Q Yt obligation. Do it Now. hIowever, ItAini News does sympathize with it. Here are two with those of its readers who aen' desirous J. E. SMITH of keeping fully abreast of all that is going Presiden, on; and to the hest of its ability, it will This J 1 Dept. 33SS present ideas the use apparatus with for of Book National Radio Institute which will be receive as many it possilde to Rad1O . Washington, D.C. different systems as possible. Apparatus Free! _Exvett '1 manufacturers, too, are keeping this con- tingency in mind; and, while different tele- ail Cou onNOW vision systems permit of varying ranges of speed we J. E. SMITH. PrraidrN, and detail of pictures, shall un- Dept. 3355. National Rada., In- itute. dmuhtedly have soon combination dises which Washington. D. C. I)ear \Ir. Smith: Send me your hook. "Rich Itrw:trd: may be used, by simple adjustment, for re- in Radin." I want to know about the money-making images, opportunities in Radio and your practical method ception of coarser or finer at dif- of training warn at honte In their spare tine to become ferent locations of the glow-lamp and scan- Radio experts. This request does not obligate me. ning hood. And, too, we may before long Name . ..Age find the scanning -disc system entirely super- seded by more refined electrical devices. Address... City. S1a:at, This is Radio's Bi a est Year James Clerk Maxwell predicted the laws of radio in 1867. Please ,fuv t'i,a saw it in K. -IIJI(J .\'G11'. www.americanradiohistory.com 476 Radio News for November, 1928 Synchronized Broadcast (C'ottinued front rouge 426) and another switch opening and closing the mie television -lamp circuit. RADIO To maintain the scanning disc of the re- NEWS OUTFITS ceiver in synchronism with that of the trans - mitter -a requisite to the production of a HANDIBOOK "A" FILTER recognizable image -delicate adjustment is necessary. This, as in other manual syn- chronizing systems, is accomplished by the simple expedient Of varying the series re- sistor of the motor; this is a task quickly Mastered by the experienced operator, but one which requires continual attention. PROBLEMS YET FACED While this exhibition is in the - widest sense "television," it is not true radio vision - hearing exactly the same relation to the Latter that the "Wired Wireless" described A recent development, which in last month's RADIO NEWS has to the converts any two or five- ampere broadcasts picked up by the listener's aerial. charger into a 4 or 6 volt "A" 'l'he problems of operating such a television Supply Unit in less than a system over wires are very similar to those of in minute's time. broadcasting; except that the latter case modulation and demodulation of a The "A" Filter consists of a radio frequency are necessary to obtain 5,000 mfd. capacity dry con- (listant transmission. And, at the present A Guide to Radio denser with two specially de- time, wide -frequency channels are acquiring For Every Fan signed chokes completely wired n value comparable with that of the. Kohl- within one unit. maw, which is har(lI' rarer. No radio enthusiast should be with- Whether the medium of transmission is TOBE "A" FILTER $18.00 out a copy of the Radio News Ama- ether or copper wires beam's but little on teurs' Haridibook, the most com- Just attach your Charger the main problems, of creating the. "vision - impulses" at the transmitting end with suf- plete chronicle of radio advance- IPrite for Literature ficient energy to impress them on a photo- ments available. Every known Tobe Deutschmann Co. electrical system distinctly, and of synchro- development, each worthwhile cir- Canton, Mass. nizing the receiving mechanism until a clear cuit, various methods of amplifica- image will remain in the field of sight. The tion, electrifying battery sets, all problems of amplifying a "television-fre - theories and practices, -in fact, BARAWIKTÀDOLDI?ELIABIE quency" hand. wider than the audio bind, everything noteworthy that has through many powerful stages, are also alike occurred since the beginning of in either system; though broadcasting and radio is fully treated. Hundreds wire -line transmission have also well -known of the most popular radio receiving ADIO SERVICE specific problems of own. In their any event, Radio Fans, f om yback hen.' will remember circuits of all times -circuits rang- the exceptional se,. we that B wik reu eyed we may look forward with confident expec- be getting radio parts likee eins hem' ing from the early type of crystal teeth, upon the scene. 6arawik was always tation to a not far -distant day when we ready too deliver the developments n radio it. customers the sty. when change. were sets to the latest and most elabor- (os stem shall hear and see together from a single, if Today. Barawik has grown to be a mighty inetb complex, assembly of receiving ate multi -tube receivers of the to ion the radio world. ail apparatus. reliable merchandise of the w id'. lé d -- present cir- iadiio manufacturers-everythingerything from min- day; And with each pie. sets to thehe smallest`` individual parts ro nr.e set builder. You a depend cuit there is a complete set of con- rí" the reliabilityaof ik tond Y depend upon Barawik's ability to deliver the "Ventilation" in the 227 -Tube in kind of servire that mean. time saved in wait - structional details explaining ¡ You nd pendu n Barawlk's honesty, by nod a tneuio serve you -And. laut. Obtained Mesh full the principle on which the hot dy from least,I tsut, you know that Ba s big discounts auure you of the lowest operation of each receiver is based doss -plea, that mean huge uviop to eau in the mesh -plate instead of a con- everythinger. you buy. together with instruc- The new," in radio act.. puts, kits. nrpplies- WHYtinuous sheet of metal in the UY -227 step -by -step sil under one roof-ready for you n. hood coupon now for big new Catalog -Free heated- cathode tube? Many users of this tions for building. ta tube have wondered about the reason for 9 Every a BARAW I K CO. in "fan" should have copy this change the design of the outer ele- of this book. Its con- I I r C Canal Sta., contents s ment. a in CHICAGO, Now stitute complete education H. S. A. During the development of this type of radio. The handiest of reference Ót.BonK tube, the laboratory engineers found that guides. A real encyclopedia. Fill MaettaA ;WO' ." s C.t9.' emission of electrons occurred, not only in the coupon now. Do not wait. from the cathode, but also from the cylin- Get your copy of this most valuable drical grid and plate unless they were rela- of radio books, THE RADIO NEWS AMATEURS' HANDI- YOUR tively cool. This would be an undesirable BOOK. $ SAVES condition in the operation of a device of this kind, as it would set up conflicting currents 116 pages-Fully Illustrated SPEAKER in a radio receiver. Large 9 s 12 To allow the The CRAFTSMAN plate to remain cool, and to THE COPY Dollar Speaker is guar- eliminate undesirable electron emission, the 50c anteed to relieve speaker use of a wire -mesh plate was adopted, thus WRITE DIRECT of plate D.C. (180 to 250 allowing the escape of much of the heat Experimenter Publishing Co., Inc. volts). Complete Pro- generated by the heavy current through the One Dollar 230 Fifth Avenue, New York, N. Y. tection. wattage 2.27 Postpaid. filament; the of the -type heater is :3r4 times that of the 201A filament, -type EXPERIMENTER PUBLISHING CO., INC.. CRAFTSMAN RADIO and the generation of heat consequently pro- 230 Fifth Avenue. New York, N. Y. Gentlemen: Enclosed and 50e.. for which send me a PRODUCTS portional. copy of RADIO NEWS AMATEURS' HANDIBOOK. 9OrchardSt., Newark. N.J. Name Hertz discovered radio waves in 1887, Address Insure your copy reaching you each month. Sub- twenty years after Maxwell calculated that scribe to RADIO NEWS -$2.50 a year. Experi- they must exist. City State menter Publishing Co., 230 Fifth Ave., N. Y. C. Please say cou saw it in RADIO NEWS www.americanradiohistory.com RADIO DIRECTORY MAJESTIC CONE RADIO - I you want AMERICAN Natural "torn of Tone hours List s_rvice per tube, LITE - Price Designed insist upon 512.50 for use with or PERRYMAN TENNA YOUR without PRICE power Moisture -Proof Extension Cords RADIO TUBES $2.25 tubes Write for details Sub -Panel Brackets I tirnbarh Extension Cords permit -The tubes with he tv. the shock- Sub brackets Poor aid the Loud Speaker to moved patented -panel in various any room to the house. Attache, proof bridge." sixes ranging from 1" to 2 1 Instantly. Install a Ill rnbarh Cord In height and from 7" to 11" .k tube for every' radio AMPLIFLEX LOOPS and put an end to distortion s pur- in length. Cut Illustrates No. Padding Rnilt -in pose. All the A.C. types. II. Write for literature. Collapsible, -- often due to badly tin datetl cords. Compass. List price. $12.50: our Your neighborhood denier has the-c Write for literature. 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The human O'NEIL Dynamics Television Tubes ear could The Thls marvelous new not detect Ray henn I: imo Speaker c, THE Laura. which radio further Hit of engineers call the t o Il e B.B. L. greatest de, dot, proveme tut t Ment hl tetes he Season Marsha 1 Silver- now in stark. than 660.171A UNIPAC MOTOR Two typas- - Be the first In your given by, one for A.C. Supplies nplete .\a -C" l"'o1 locality to build a iteration. the er. Contains built -In push -Pull teiev[shot receiver. lion stage requiring two An improved motor for loud speaker order other for D.C. Equlnilel with our tmidiliea operation. Power without saturation. Send money Samson Symphonic ddynamic unit:. Beautiful two-tone 171A type power tubes. NOW. List Price Wired 576.00529 50 Eddy currents reduced to minimum. Transformers sv:duut finish to match thelwpular Permanent adjustment assures the ets. Write lilrr11111, YOUR COST $12.50 !u Cost highest quality tone reproduction. Send for full information In Kit Form -Your 526.50 Irrite for details Newark Elec. Co. O'NEIL MFG. CORP. ALL NEC SEALED CARTONS. 220 W. Madison St. West New York New Jersey RAUNER RADIO CO. BEST MANUFACTURING CO. Chicago, III. SAMSON ELECTRIC CO. 142 Liberty St.. New York City 1200 Grove St. Irvington. N. J. Canton, Mass. 200,000 SPEAKER TABLE RADIO NEWS readers carefully scan the RA DIt) Bruit Kul Col- Dl1iECTOttY every month. onial design. Solid walnut, YOUR product here, at hand rubbed. the lowest cost in the IL_ le Size, 30" x world's largest and most 1211" and 31" widely read radio maga- zine. high. M :1 d e BODINE BAKELITE and RATE CARD: E<-- -- -1 r 1 t Il Temple ELECTRIC TURNTABLE Air - Chrome Per Issue r HARD RUBBER Three time rate 525.00 For dis- Pwnu: ru ph nuhinxtions ENGRAVING speaker or for dynamic speak- -110 brunies. 1 1111:Iinrs. t DRILLING - one Six time rate 23.75 er. This is only of many parking. l'o+dt irel um inter- PUNCHING - STAMPING beautiful reatlons for Twelve time rate 22.50 Latest Circuit Panels in Stock Fritts No order for less than ference in the loudspeaker. We rater m retail as well this year. pyrite for full Write today for full U,,rornlatiOn On and tree catalog. three Insertions accented. as manufacturing trade. particulars Write for information. this big new development. Cortlandt Panel Engraving Co. D. H. FRITTS & CO. ELECTRIC CO. Dealers, write La' rat alog. 604 Hearst Bldg.. Chicago Radio News. 230 5th Ave. BODINE 165 Greenwich St.. N. Y. C. 2242 West Ohio St.. Chicago. III. W. C. BRAUN CO. 552 Monroe St., Chicago NOPHONIC TUBE SEND FOR NEW Pacent FAMOUS CAPS FAHNESTOCK RADIO BOOK Stop That CONNECTION All the new hook -ups. Howl! CLIPS Parts, supplies, A.C. PHONOVOX etas Carborundum To get the sets, television, short best from Fixed Crystal Detector your set. be THE ELECTRIC emE Pahnestoek wave, etc. Fixed Crystal Detctor that up18 meet every sure demand of the Wr'ile for free copy Bell- clear. Noiseless, Sensitive all tubes PICK-UP radio public. Will bring lammed tones hl ITid e m p l o y n oz'. to pram teally any set. Can Stops 1.70e them for apllrtrmee. positive he Nophonic Tube Caps. ontact. and durability. Write for atijltated to suit ynir set. CÍ the filament. From :dl Bratton of Pacent Electric Co. abalod or pick flan out at your dealer or direct-31.50 I. i.t trice 25e Inc. I carat dealers. THE CARBORUNDUM CO. . I.st your dealer or write direct tolaur FAHNESTOCK ELECTRIC Write for Hunk -op honk MERTZ SPECIALTY CO. York CO. 211 B Canal Sta., Chicago D -1. 1306 Stockton Street 91 7th Ave. New Long Island City. New York Niagara Falls, N. Y. Wilmington. Del. SAVE YOURSELF MONEY e NAME Send for This SEND SET BUILDERS '1 e have a new illus- DEALERS! PLATES trated catalog showing FOR Save money. tI 0e BRAIDITE our up - to - the - minute ami bit lier Lv WE SPECIALIZE Hook -Up Wire stock of kits. parts and OUR purchasing kits IN NAME PLATES OF sets - everything you rad parts from ALL VARIETIES: i'The Braid Slide.; want in us. 3f aSimumdis- Back" radio - all at DE JUR MONEY ETCHED PLATES, Slake your connection. solder dealers' wholesale prices. VITREOUS ENAMELED counts to dealers. EMBOSSED PLATES It and the insulation slides Write POWER RESISTANCES Latest kits and bark Into place. today for Catalog SAVING parts always In RADIO ESCUTCHEON PLATES "11-1." Pur "1s" ellininatoni, power ampli- Ifightf your dealer can't .auPPIY stark. Send NOW Write for Samples and Prices. yin,. Order duvet fiers and electric sets. These resist - CATALOG for catalog. are backed by Pi years of eon - 25 Ft. Solid. 30e ALLIED RADIO turtsinmoll', s:lttcf:rrtory service to the ETCHED PRODUCTS CORP. 25 Ft. Stranded, 35c CORPORATION Wholesale Radio Queens Boulevard. radio publie. II -rile for catalog. Service Co. CORNISH WIRE CO. 711 W. Lake St. LONG ISLAND CITY -N.Y. Church DE JUR PRODUCTS CO. flow GR Church St. 32 St.. New York Dept. "B-I," Chicago, Ill. 199 Lafayette St.. New York. N.Y New York o The RADIO DIRECTORY is your buying guide. Space permits display of only one product at a time. Write advertisers for complete catalogue. www.americanradiohistory.com Radio News for November. 1978 THESE MAGAZINES THEfPRICE A year's subscription to these OF Canada and in Europe. This list two popular magazines for the of call letters is carefully checked price of Radio News -alone. If and corrected in each quarterly you were to buy Radio News and edition. Radio Listeners' Guide and Call RADIO NEWS is read each Book individually for one year month by more radio enthusiasts they would cost you $5.00. By our than any other publication in the special combination yearly sub- field. It contains the latest devel- scription rate you can get both of opments and the most modern cir- these foremost radio periodicals cuits of the radio world. Honest, at the tremendous bargain price of unbiased opinions on every sub- $3.00. In order to keep up with ject of interest -this is what the latest developments of Radio, RADIO NEWS gives you. to know the newest sets and how to build Write today- insure your re- them, to find every radio broadcasting ceiving each issue of RADIO station , you must read these leading peri- LISTENERS' GUIDE a n d 0 odicals of radio. CALL BOOK and RADIO NEWS. Take advan- \' The RADIO LISTENERS' / ° GUIDE AND tage of this special Fe `°` re CALL BOOK is the foremost quarterly subscription cagy \\ offer- /4- ße0we magazine in the field. A special feature of T w o magazines / age \o1 / 4P \e o this remrakable magazine is the up- to -the- for the price a4-'°oa of ¿0 er minute log of every station in this country, one. / r' c t oc + o Ó Special Combination Yearly Subscription Rate 1 / Gae / Jp4Q7v4.0 ca $3.00 ßea a°ae For the Radio Listeners' Guide and Call Book and Radio News / 4 °\° sly .*<6 / 6r ° EXPERIMENTER \eFwc PUBLISHING \tiPw. Please cal, you saw it a 1i . 1 17 1 0 .\' E ll' .ì www.americanradiohistory.com 479 Radio _\'ewes for November, 1928 of Justice" "Rays t R L R L (CoNliuf it fen ua tua,le -1:;:S) Jai Unanimously the engineers diagnosed the trouble as being caused by too -small in- sulators. Feverishly they set about to de- SCAN THE sign a new insulator of huge proportions which no current under a million and a Half volts could possibly break down. This, ETHER the engineers felt, would by its sheer size alone render failure impossible. Yet all the time they were haunted by the uncanny WITH way in which the two insulators had broken down -at identically the same point, at the same time, in the saute way. The laws of The New probability utterly forbade such coinci- dences. The interest in the proceedings was so "222" widespread that the public- spirited I-Iarold Dare, at the suggestion of his thoughtful public- relations department, arranged for SHIELD the broadcasting of the installation of the GRID new insulator. As if going on location, a whole company of fechniciaos from the Dare studios set out from Hollywood, trans- porting with them all the equipment neces- Combining the proven, hyper -sent Live connection with the regular tele- STROBODYNE system with the tre- sary for mendous amplification obtained through the vision channels. The power truck with its use of the new shield grid tubes, in a special gasoline -driven generator outfit was placed circuit making full use of their extra high amplification factor. behind a ledge of rock several hundred feet ,away, lest its deafening noise spoil the The "222" STROBODYNE audio part of the broadcast. At noon they Latest Design by came on the air through WROT, and R. E. LACAULT, E.E. throughout the afternoon continued to re- leaves far behind all other types of sets. Its performance port the progress of the work to a thrilled has amazed experienced engineers and it has come through citizenry touched anew by the thoughtful- hard tests with flying colors. ness of Harold Dane, thrilled with the op- SPECIFICATIONS portunity of witnessing this dramatic en- 1- QUALITY OF REPRODUCTION gineering crisis: Through the use of high grade audio transformers com- the linemen bined with a push -pull amplifier and the best method of It was not until dusk that detection, the most remarkable fidelity is obtained. The were finally whipping the heavy cables into results will amaze the most critical musicians. place, and huge daylight arcs were already 2- VOLUME The tremendous amplification of the shield grid tubes flooding the ridge with light. The television produce unusual volume which may, however, be regu- pick-up device was sent aloft in a captive lated to any desired value through a special control. balloon to the level of the tower top. .\ 3- SELECTIVITY The very high impedance of the shield grid tube, com- spotlight played upon the linemen who were bined with the special circuit used, makes the tuning putting the finishing touches to the last very sharp without affecting the quality. splice. The tension tightened as the crucial 4- SENSITIVENESS The sensitiveness of this receiver is so much greater moment approached when the Wolf Creek than that of any existing set that it is beyond com- would be put under test. parison. There is NO LIMIT to the range. The noise line level is the only factor affecting it. Then Fate took a hand. Perhaps the 5-SHIELDING strain was too much for the long span of Entire R.F. system completely shielded. cable which carried current from the gen- 6-EASE OF CONTROL Only two dials, a volume control and sensitiveness con- erator to the half -dozen flaming floodlights. trol are used -making the set easy to operate. A wire sagged, broke; an arc crackled, and 7- STROBODYNE SYSTEM the ridge, The STROBODYNE method of reception -a time -tested dankness plunged down over and proven circuit -is incorporated in the set, causing while the thundering power machine raced very weak signals to produce a tremendous response. wildly without as load. 8- MATERIAL Only the very best of tested parts are used in the entire But the screen of the televisor was not set, insuring permanent high efficiency. dark. .. million people gazed horror- 9- DESIGN cross -arm of The new "222" STROBODYNE is designed by R. E. stricken; for to the topmost Lacault, E.E., well known creator of several famous the Inge tower cline two living skeletons circuits, whose reputation is a guarantee of the high - set. skeletons whose hands clutched pliers, skele- grade radio engineering incorporated in this tons that shouted hoarsely for lights! It was but a moment until electricians Read how to build it in the September issue of Radio News had repaired the broken wire, and the light: and Blue Print No. 63 flared forth again; but from their room in the Hollywood laboratories, Dare and We are equipped to give you his engineers had seen all. The great screen star reached for his telephone; a few words to the operator and his transmitter was PROMPT MAIL ORDER SERVICE switched into the microphone circuits of All genuine parts carried in stock \\'ROT. ;\ moment later his voice was reassuring thousands of shocked and shaken Special all was well, that the EXPORT ORDER DIRECT from radio listeners that Department strange mystery which perplexed the world's best engineering talent was on the point R. E. LACAULT, INC. of solution, and that if they would have patience, all would be explained. 116 Nest 65th Street, Dept. 405, New York City Then mysterious telephone calls began Cable Address Long Distance Phone to fly about Hollywood, and in answer, ears LACRAD NEW YORK SUSQUEHANNA 2095 Pten.tr sur you sore it in RADIO NEWS www.americanradiohistory.com 42SÚ Radio News for November, 1928 came speeding from all directions to the sacred inner court of the Dare studios. At the Dare private flying field, a score WHITEHEAD ER° 10, of lien suddenly appeared; the doors of the hangars were opened, and two speedy EXPLAINS THE pursuit planes roared forth and vanished into the night., And at Wolf Creek, a crew of linemen, acting upon mysterious orders GAME OF BRIDGE that had come by telephone from certain high offices, worked for an amazingly long time at a simple task that should have re- World's Greatest Authority INTERNATIONAL quired not more than twenty minutes. Reveals Secrets of Success An hour and at half had passed when Short -Wave Converter three ears with lights dimmed low sped tip Will Add Thousands of Miles the bare pretense of a road that led up to To Your Receiving Range the scene of the engineering catastrophe, Wilbur C. Whitehead, in his master Broadcast reception on short waves is re- to discharge a grim group of nlen. At a instruction book, "BRIDGE," passes markably clear and free from static. Pro- word from grams are brought in froni greater distances their leader they separated on to the beginner the secrets of with the utmost simplicity of control. into two groups anti set off in opposite di- You the game that made him famous. can easily build the Aero International rections. Then Harold Dare himself stepped Short -Wave Converter and receive short- "BRIDGE by Whitehead" is a programs on your present set. No out before the battery of floodlights and new csavehanges in wiring necessary. Just plug into spoke into the microphone standing on and absolutely unique instruction detector socket. a method for AERO KIT No. 9 $38.90 pedestal. the game of Bridge. It employs what Whitehead is pleased THE "Friends," he said, in a low, earnest "STANDARD" voice that found instant response in the to term the "picture method" for in- Cn extra tube is struction. Every in ::ceded for this heart of every listener, "there is one who play the game Aero Short -Wave has plotted for years work of Bridge is fully illustrated. There Converter. Plug to my ruin - into detector sock- a veritable fiend in human form, whom all is page after page of illustrations, aet f your receiver nd insert the tube the world knows and hates. As principal showing every conceivable hand, also which you re- Moved from set stockholder in a certain power corporation, adequate text matter to fully explain AuutheConverter. he has clone his Kit Is complete utmost to hurt me by en- each play. Everyone can learn to with all parts. Can dangering the confidence of the be assembled in a public in play this popular game by this easy few minutes. For me and my new power project. A.C. or D.C. re- Dandy method. ceivers. 1)iaolo and his minions are responsible for Price -532.00 the three successive breakdowns in the How efficient are you at the play? Wolf Creek line. irrite for information about the ge m What proof? See for Do you 1929 Aero Green Boot know what to bid and when yourself. Watch the three insulators which to bid it? suspend the Can you explain the follow- cables of the Wolf Creek line." ing accurately: the auction; the book -The crew of linemen scurrieddovn pINCORPORATED from and odd tricks; rank of bids; the pass; their tower. One by one the Dept 18$ 4611 E. Ravenswood Ave., Chleage,,114 floodlights the double; dimmed. In the televisor the redouble; the contract; was seen the who is group of large strings of insulators hanging the declarer, the adversaries, from the cross -arms. the dummy? Can you keep score? What are honors, slams, the "Now, operators at Wolf Creek are start- rubber? ing the turbines, sending half a million These are but a few of the many corn - g510 4Z5 volts surging along those cables." ponent parts of the game of Bridge. Charging Batteries 0; A faint glow appeared about the ends Whitehead's new method will make of the insulators. Momentarily it grew. this fascinating game easy for you. Starts You A tongue of light darted out from the cable, Let me show you how then spat across to the to make big money corona shield and Read "BRIDGE by Whitehead." No right from the start. vanished. A flickering halo encircled the one is so good a player that he will I've prepared a FREE tips of the insulators, book explaining all details. First gradually spreading not benefit by this valuable book into a luminous cone. - week's profit pays for all equip- 'l'hen suddenly a band no one so poor a player that he can- ment. You can get all the battery of flame ripped across the gap. With charging business in your community with my a not become expert by following Service Station Charger -it's years ahead of or- report as of a cannon, two huge insulators dinary chargers- handles 50% to 70% more plunged downward. Two heavy cables swung this wonderful instruction course. batteries. I explain everything -start you in a business of your own and put you on the way to sinuously out against the tower; two bursts big money. Write for FREE BOOK. of flame, a shower of chops of molten cop- Over 100 pages. Each play C. F. HOLMES, Chief Engineer, Dept. R.N per, and the line was dead. illustrated Independent Electric Works Large 9" x 12" size 5116 Ravenswood Ave. Chicago, Ill. "Lights!" cried Dare. From the truck which had been backed to the edge of the cliff, two huge searchlights suddenly shot long shafts of light' downward into the IIIE COPY depths of the valley below; and where the 50 C two accusing .fingers pointed,- the ttcgrld FREE Whok.a'. Radio saW a group of swarthy,. cyilfnced -nten AT ALL NEWSSTANDS OR Set Builders -Dealers! Save Money!Catalog gathered about a truck almost entirely WRITE DIRECT TO THE Send for the most complete book of nationally known screened from view by the surrounding Parts, Kits, Cabinets, Consoles, speakers, Power Units. Sete etc. All at lowest wholesale prices. Quick service shrubbery. Even as they leaped to their on all your needs. Write now, it is FREE- feet, n dozen stalwart SETBUILDERS SUPPLY CO. men stepped out of EXPERIMENTER PUBLISHING CO.,Inc. Dept 13.3 Bomberg Bldg. Madison the darkness on all sides, guns in hand, and Market Sts. CHICACO,IIL 230 FIFTH AVE., NEW YORK, N. Y. and the henchmen looked into a circle of menacing muzzles. With one accord they raised their hands heavenward. EXPERIMENTER PUBLISHING COMPANY. Inc. 'l'he operator of the televisor adjusted 230 Fifth Ave.. New York, N. Y. his instrument for a close -up. Gentlemen: Upon tele- Enclosed find 50e., for which please send me :t copy 01 sep pace with radias newest l. s- A.C. go vision screens everywhere, a group "BRIDGE by Whitehead." tube. dynamic., television. .cores of devil. of .ai ce radio' dawn Bar wik`In kept si range instruments :and glass ahed bby bigger node.. a. lowest tubes of sea Big New RadioGuide is now ready -send f or it. peculiar shapes Were seen to cover the Name Wholesale discounts to set builders, deal- is and agents. truck; and in the foreground glared the Address BARAWII< CO., 2110 Can,ISta..Chicaeo.O.S.A. cruel, evil features of Dandy Diavolo. I-Ie shook his fist toward the brilliant bears rtv 'hate Please say you sate it in RADIO NEIVS www.americanradiohistory.com Radio News for November, 1928 of light which sought him out; his features twisted into a typical Diavolo sneer, and as clearly as if in a sub- title, the watching The New Knapp "A" Power Kit world read the words the thin lips shaped: "Foiled again! Cur -r -rse you, Harold Dare!" * . - "The basis of my latest plot," said Dandy Diavolo in a public statement an hour later, as he was being swiftly transported in a cabin plane to Los Angeles, where the agents of justice awaited him, "was dis- covered by Hertz half n century ago, when he discovered that ultra- violet light facili- tated the passage of a spark across a gap. It was later found that this was due to ionization of the air, and that the effect was intensified if waves of still higher fre- quency were used. In order to put the Wolf Creek line out of commission, I set up a bank of powerful X -ray tubes in the valley below a tower on the Wolf Creek line. The beams of X -rays thus projected upon the insulators ionized the air so that the high voltage easily ,jumped across over the insulators, which were already under severe electrical stress, as indicated by the corona. No matter how large an insulator had been placed on this tower, the current would still have broken it down. Only the long arm of coincidence saved Harold Dare, as always, from the working of my plot." This is the 'A" power after you hare as- "What have you to say as to the way se bled it. A professional job: Operates on in which plot was foiled, Mr. Dare?" 105 to 120 volts, 50 to 60 cycle. AC. Supplies the Greater rippleless DC current for operating any set asked a reporter. using Standard 5 or 6 colt tubes and power "To set at rest the fears of my public regarding the skeletons which Were seen Efficiency- to upon the tower, let me first assure them that they saw merely ordinary X -ray pictures of the linemen at work, exactly as if taken Improved Design and Appearance-Lower by a doctor's X -ray. The photoelectric cell used in the televisor responded to the N -rays Price -Money -making Plan for Set -Builders from Dinvolo's tubes, which, traveling on through the linemen, threw shadows upon You radiofans who made myttA" power the largest sellingttA"power the television field. When the lights were last spring have made it possible forme to offer thefinestttA"Power on, these shadows were too faint to he seen; ever developed -in Kit form -even more complete than before. but when the power was accidentally dis- Study the illustrations-read the improvements -and you will connected, they came into prominence. Let wonder how I was able to reduce the price. You are the answer. I me merely remind my public that this epi- sold 5 times as many "A "Powers as I expected to-and this season sode reiterates the great truth taught by I am counting on you to help me again by buying even more. every Dare super -special: namely, that in the end, right will inevitably triumph over THE SET- BUILDER TAKEN wrong, and evil -doing will receive its just The 8 Improvements punishment. The long arm of coincidence I. Larger Filter System -3 Elkon CARE OF is merely the agent of ,justice, which, act- Condensers instead of 2. Ideal You set -builders played with me (as the hand of Fate, always for Super Hets and Short Wave the saying goes) and I ám going to ing also through you. My engi- finally catches the wrong -doer in the clutch Sets. continue to play with neers have designed an "A"a Power of circumstance. This time Dandy Diavolo 2. Improved Choke Coils which is well -nigh perfect -my pro- has gone a step too far.' Retribution has duction men, based on tremendously overtaken him, and during the next score 3. Pendant Switch Controlling "A ", large quantities have cut their cost. or more of years when he will sit in the "B" Eliminator & Set so that I can keep faith stone cells of the penitentiary, he will have 4. Dial for regulating voltage with you by reducing abundant time to meditate upon the truth the cost. And regard- 5. Celeron Front Panel less of what the estab- of this statement." lished trade may think 6. Baked finish about it -I am going to A BIG CONSTRUCTION JOB 7. Heavier gauge metal cover continue to give you the VAUDEVILLE FAX: "Which do you prefer, maximum discounts. the Keith or Lorw circuit ?" 8. Die Cast Base Plate instead of wood The coupon will bring RETIRED HAM: "I can't really say; I you the full details of haven't built a set for some time." both the new"A"Power COMPLETE KIT-EASILY and the special dis- counts to set -builders. David W. Knapp, Pres. HE HAD A GRIEVANCE ASSEMBLED ":4fv name is William Ransom Nathan Like my Kit last year, the New Knapp Young!" roared the angry caller at the Kit is a tooled job parts seem to KNAPP ELECTRIC, Inc., Port Chester, N.Y. -the -Div. P. R. Mallory & Co., Inc.- broadcast station. fall into place. Every hole is drilled - r "What if it is?" asked the polite attend- all that it is necessary for you to do is Mr. David W. Knapp, Presiders:, ant. to put the screws and nuts in place KNAPP ELECTRIC, Inc., and connect a few wires. Everything 400 Fox Island Road, Port Chester, N. Y. "What if it is!" thundered the caller. is supplied. Nothing for you to buy Kindly send me complete information on the "Why, this station, without getting my per- Knapp "A" Power and your special discounts for extra. The fool -proof instruction Set- Builders. mission, or asking me, is using nay even sheet makes it easy for anyone to Name ...... initials! " -Gut/ T. Ermax. assemble. Address (We advised him. 'to have it changed to Kasper De Koren Awberson.) nl ° ^e sa,, rou Saw it in RADIO NEWS www.americanradiohistory.com 48d Radio News for November, 1928 BaneryCltp Sensitizing the R. F. Amplifier rOWLarpL TINe1011 (Continued from page 453) PF-250 duces distortion. However, the potentiom- eter may be removed, the grid return Power Transformer for an changed from the movable arm of poten- for uninterrupted tiometer to minus filament, and a variable flow of resistor (of 200 -500,000 ohms range) in- UX 250 Power Tubes Electrical serted in the plate circuit. An increase in A husky transformer built for doing the Current selectivity will be noted, while the plate cur- job, not for looks. The PF -250 is rated at rent drain will be materially reduced. 1200-600 volts plate, 75h volts power tube, 73i volts rectifier tube filament. Center REMODELING THE NEUTRODYNEe taps are provided on each of the filament The neutrodyne circuit may be rendered windings. Continuous rated capacity of more sensitive by removing the neutraliz- plate windings, 160 MA., continuous rated ing condensers and controlling the R.F. capacity of each 755 volt winding, stages with a suitable variable resistor, 3 Amperes. DC plate output with Better placed in the plate circuit. Radio enthu- two U X 281's full wave, up to Contact siasts, anxious to secure real distance with 450 volts with sufficient ex- neutralized sets, have sometimes replaced cess for "C" Bias. the fixed neutralizing condensers with tiny Ask for Bulletin No. 1033 describing Powerful variable condensers, together with a suit - fully the PF250. Tension able indication to show the normal adjust- ment for each condenser. A simpler method Price, each -- $30.00 Grip -Tite Battery Clips assure is to employ variable plate voltage, as S'ghtly bigler aQ,t of Rod, Mnunr.in, RHANCO men- better contact. Hundreds of thousands tioned; for then a single control takes care have been sold and are giving complete satis- American Transformer Co. The de- of the entire R.F. amplifier. faction today. Here's the reason. Tasformer Builders for more thon rt Ymir sign is right and assures free and un- Lately the grid-suppressor method has interrupted How of electrical current. come into wide favor. This comprises a 263 Emmet St., Newark, N.J. There are no springs to heat up or burn or 200- to 1800 -ohm fixed resistor, depending drop out. on the circuit conditions and the tube, Shanco Grip-Tite Battery Clips are acid - placed in the grid lead of each R.F. ampli- resisting and are made of special powerful fier tube. The grid -suppression effect of tensioned tempered spring steel, solidly riveted together. ALL parts are electro-plated a given resistor becomes more marked at before assembly (not galvanized nor tinned). higher frequencies, or lower wavelengths, The jaws open wide and are easily applied. which is a most desirable feature, since the Grip -Tite Bulldog Teeth "stay put" and bite right through corroded bars and tendency of most R.F. amplifiers to oscil- terminals. The teeth are so arranged that late increases with frequency. the clip cannot fall over and short the battery. Here is a compact, solidly built battery clip that is a big value and a permanent invest- ment. There are four sizes for every battery WHEN TIME WAS MONEY ampere, fifty need. Five ampere, fifteen LABaY: $1.15 a ampere and three hundred ampere. "They say it cost second to broadcast the Democratic National Con ILMail the coupon at once for our special vention." low prices and complete information. SANDY: "Gee! what a.spendthrift that an- nouncer was, with DYNATONE DYNAMIC AND SHANKLIN MFG. CO., his "Stand by one mo- Dept. 72, Springfield, Ill. ment, please' ! " -ITrm. G. Mortimer. MAGNETIC REPRODUCERS Gentlemen: Please send me complete information on your Write for information on the new Dynatone special Radio Battery Clips. No obligation, 40-cycle reproducer. Brings out bass and of course HOME, JAMES depth from any set. Full dynamic movement. There was an announcer named James, Name A favorite indeed with the dames: Dynatone Electromagnetic Units ....$12.50 Complete with 7 But they all had to smile -in. Cone and Baffle. 18.50 Address Every once in awhile Sold under 10-day money-back guarantee. City State When they heard him pronounce foreign Send check or money-order in advance or d names. pay postman. á ALSO -Mrs. Fred W. Auroache. Complete set of blueprints and instructions DABLE "B" BATTERY POWER for building your own DYNAMIC moving coil unit. with cone and baffle. New design TO ERR makes home construction simple with few IS í % tools. Guaranteed to work. Sent postpaid anywhere upon receipt of $1.00. FANSPEAKER RADIO COMPANY 74 DEY STREET - - NEW YORK, N. Y. 'NE LN00t RApAto tXOE0.T C. tESTURECLTYou¢ l / toa,lanplocme- ` t, .;t1jl' ANO AFTtRNololNg You MIA/woo FOR AN NOuR WITN,HCOntTIOAL DET,M1r AE Acoto sets Tax 4t Wal NOW Slut A DtMON;TWNTION OF OM VET eAntV11- 100 Volt Edison Element. Non -Destructive. Rechargeable "B" Battery with charger. Shipped dry, with solution. 812. 140 Volt with charger. 517. 180 Volt Power Unit. with Wholesale Trickle Charger. 824.00. SEND NO MONEY -PAT EXPRESSMAN Prices Write for ear Free Literature _,^ ` ,_s (9 ) SEE JAY BATTERY CO., 915Breok Ave.. New York úEA \ Everything in radio -kits, parts, -Ax0 AFy-n 101Cau `/VW, So aLTwN N RAt,Ñ TTjTut TUBES/ accessories, sets. Improved de- Oe NICE wt AE TINOS TuNT. signs and styles. Makers nur Big selection at Liatpae worthwhile saving. Immediate of high r Eavox quality service; personal attention. Send resistors and for complete, illustrated Cata- condensers that are log "B-1." Built Better - to endure. r N ,77,, Ns_ Write for The Research Worker. uFxJt2tEn.E-ÌAAT 6QANDl' ANS (fLORIOOS fEEl.IN6! A free monthly publication. AEROVOX WIRELESS CORPORATION 68 Washington Stre t Brooklyn, N. Y. -The Wireless Constructor, London. 711 W. LAKE STREET. CHICAGO Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio .News for November, 1928 483 The "Pre- Selector" (Ct.litinle flout jape 440) Model it may be necessary to use New Admiralty into the receiver, a "B" battery for the Pre- Selector plate In that case two of the small 22%- supply. - volt blocks ordinarily used as "C" batteries NORDEN H UCK will serve the purpose and their life will be about a year, due to the extremely small lilate current drain. SHIELDED SUPER-10 The proper connections for the batteries 2 3. In these clia- are shown in Figs. and Composite View _rauns both the Pre -Selector and receiver ' o f Admiralty In most Shielded Super. are shown connected to ground. 10 showing ins, eases it will only be necessary to ground portant details of one. The best plein is to try grounding each s +s, design and con, de- scyuctiorl. individually, and then both together, to , fi termine the best arrangement. OPERATING THE PRE -SELECTOR rf .\fter the l're- Selector has been connected and really for operation, the necessary pre- liminary adjustments of the receiver proper should be made. First, adjust the receiver dials for a wavelength somewhere above the broadcast waveband; if the exact set- tings of the dials of a multi- control re- ceiver are not known, adjust the dials as closely as possible. 'l'hen turn the receiver's volume control to the position for maximum volume. Also, turn on its filament switch; This great new Receiver is far in advance of competition. It is a filaments are to be unless the receiver's powerful 10 -tube model incorporating the most complete and up -to- turned on and off at the Pre -Selector, when the receiver's switch should be left turned date principles. Using the new screen grid tubes in the R. F. amplifier on at all times. and push -pull audio system, make this new model the outstanding Next, turn on the filaments of the Pre - development in Receiver design for years. Selector and adjust the rheostat to provide them a voltage between 3 and 3.3. 'l'urn the Pre -Selector's "Volume Control" all the Features way to the right and adjust the "Sensi- 10 tubes used. Five 222 screen grid Indicating Dieters on Panel. tivity" control so that the plates of the R. F. amplifiers, 200A detector, two Removable R. F. Transformers for all midget condenser C4 are all out (minimum 240 Hi -Mu's and two 210 tubes in wave lengths up to 25,000 meters. regeneration). the power audio amplifier. Electric or Battery operated. With the left or "antenna selector" (wave - Extremely sensitive -long range. Simple to operate -only two major length) dial of the Pre- Selector at, say 40, Totally shielded. tuning controls. slowly rotate the right -hand or "frequency Super -selective -10 lire. separation. A laboratory precision Instrument, built selector" control knob until a station is Perfect quality of reproduction. according to U. S. Navy Standards. heard. If none is heard, repeat the opera - t1/2n but with the wavelength control set at Complete attractive illustrated literature sent upon request. Full 50. It is important that the "frequency se- size genuine Blue Prints and constructional data $2.00 Postpaid. lector" control be turned slowly in hunting for stations; because the tuning with this Write, telegraph or cable today. control is so sharp that stations may be skipped over easily. Once the first station has been heard, NORDEN- HAUCK, Inc., Engineers carefully readjust the two tuning controls Marine Bldg., Philadelphia, Pa. of the Pre- Selector for maximum volume; then turn the "volume" knob back to reduce Builders of the highest class radio apparatus in the world. the volume to normal. The tuning controls of the receiver should now be readjusted to Cable -Norhauck exact resonance, which is indicated by maxi - mum volume. Also, any other adjustments provided in the receiver should be made now for maximum reception. If there are two or more antenna terminals, for instance, RESH MA RADIO SCHOOL lead should he the Pre- Selector's output YOUR ULTIMATE RADIO 1 SEND FOR CATALOG connected to the one which provides maxi- mum energy- transfer. It may be worth AT ALL MASSACHUSETTS RADIO and while to try also increasing the plate voltage TELEGRAPH SCHOOL on the R.F. tubes in an effort to increase AUTHORIZED 18 Boylston St. Boston, Mass. the R.F. amplification. This will usually DEALERS be found entirely practicable, bemuse of the greater stability of most receivers when per- manently- tuned to a high wavelength. MOrrePrDNS To.Se.t:Builders Turning back to the Pre -Selector, it will TRIAD be found advisable to experiment a little One good radio idea may be worth - EVERY WEEK 13 WEEKS millions. Barawik has thousands of ideas with and the $l A YEAR- 15 for radio set builders to make more money. the switch, S\V2, regeneration Veer neighbors V CENTS help you know the Pathfinder and you will like it- -the every- Barawik'a Big Radio Book will control, in order to become familiar with week news digest from the Nation's Center. Bright, while elections are on and big national interesting. dependable,a different -- nothing else like events stir the world. their action and effect. Finally, adjust the t. Washjegton gossip, polities, science travel. fun. lots of pictures Instruction, enteyrtainment. Send for your copy today - NOW. small condenser C3 to bring the readings of Trial seat: or for full "year. Send now. Addrs BA RAW IK CO. the two tuning dials into line. Patiiñnder,Dept. 17, Waehington,D.O. Please say you sow it in RADIO NEWS www.americanradiohistory.com 464 Radio News for Nove,ulicr, 1928 FANS: third big edition Don't Over MISS COMPILED BY THE STAFF OF 150,000 RADIO This NEWS Cdóóo Copies Big Already Issue Sold PUBLISHING CO 4".." NEW YORK CITY Compiled by the Staff of RADIO NEWS Completely Revised-Up -to -the -Minute 1001 RADIO QUESTIONS AND structed. Concise, authentic answers ANSWERS, the most sensational to every question that can possibly be seller in the radio field, is now in its asked concerning the many and varied third new and revised edition. No one branches of radio reception on both interested in radio should be without short -wave and broadcast bands. a copy. The staff of RADIO NEWS, the leading fan magazine, has striven to FANS! Don't hesitate! Get your copy make 1001 RADIO QUESTIONS AND today! Over 112 pages - fully ' ANSWERS the foremost work of its illustrated -- large magazine size kind available. There is a full and a complete explanation of every worth- o y while circuit that has appeared since 50e the beginning of radio, not only the THE COPY explanation, but also complete Co tis.0045.° dia- ASK YOUR grams from which NEWSDEALER `'e4qo 4éa' yeti: the set can be con- OR WRITE DIRECT Si 15° _°,.ti4- 230 Fifth Avenue, New York, N. Y. Please say you saw it in RADIO .\'TTVS www.americanradiohistory.com hadio News for .V ovcmbcr, 1928 COUPLING ADJUSTMENT A final word regarding the adjustment snyitleseal `'::xixMt.. of the automatic coupling arrangement may be required. 'l'he cam should be slipped over the rear of the condenser shaft, with the fiber can] toward the rear and with the fiat side uppermost. Now, with the con - denser plates all meshed, turn the cam until its toe is just level with the bottom side of the bakelite strip upon which the coil is mounted; then. tighten the set -screw in the collar on the cam. Next, loosen the set- Build c screw in the brass pin on the lower rod of along until :wl' the coil carriage; let this pin slip Your _11ü1i4 it rests against the fiber cauu, and then 1ghRi tighten the set -screw. With these adjust- ments made, it will he found .that the pri- Power T mary coil moves as the condenser is rotated o T dlri/D ant, when the condenser plates are entirely unmeshed, the pin should slide just to the Pack point of the cans. This is the correct ad- justment. Around In the event that there should he no re- ception when the Pre-Selector is first put into operation, and all connections and wir- the ing are found to be correct, test the tube used in the oscillator socket, V2. The whole ., action of the Pre- Selector depends on the oscillator, and a poor or defective tube here will prevent proper reception TRUVOLT DIVIDER APPARATUS. REQUIRED 1 . '. Pat. 1,676,869 and Pats. Pending 'l'he following is a complete list: One variable condenser, .00035 -utf. (C1); A Universal Voltage Separator -mf. (C2); One variable condenser, .00025 board or sub -panel, or used as the condenser, 2- 20 -uunf. (C3); THIS new Truvolt Divider One equalizer re- front panel on a metal cabinet, at One midget condenser, 50-mmf. (C4) ; offers you the complete the same time providing binding posts One fixed condenser, .00025 -mf., with grid - sistance combination for con- for all "B" and "C" voltages. leak clips (C5) ; structing with utmost ease a One fixed condenser, .0001 -mf. (C6); remarkably efficient power pack Price- $12.50 One by -pass condenser, 0.5 -mf. (C7); suitable for operating any type Electrad Specializes in a Full Line of One antenna coupler, with provision for au- of receiver up to 12 tubes. Controls for all Radio Purposes tomatic coupling variation (L1); including Television. One R.P. transformer (L2); By dividing the filtered voltage into all neces- One R.F. choke coil, 85-millihenry (L3); usable values, it eliminates of mathematical calculations in INC. One -switch, 50 -ohm (lt1 -SW1); sity ELECTRAD, rheostat constructing a power pack. It does VA -il N. T. One volume -control potentiometer, 25,000 - Dept. NewN York. away with a great deal of wiring and Varick St., of th' ohm (112); 175 copy the need of voltage regulator tubes. me FREE my copy l and One grid leak, 2- megohnl (R3) ; makes it possible to build a power Please send Divider for Grien' It Truvoltmailing One aerial switch, single -pole double -throw supply device which is universal in Electrad on your out and information. (SW2) ; its application. Data (V1 and V2); Two vacuum tubes, 199 -type Case made of genuine bakelite, it will ...... Eight binding posts, push -type; add a smart appearance to any unit. Name Two vernier dials, illuminated -type; Five potentiometer type control ..... 7 x 14 x 3/16 -inch; show values on a scale of high Address...... One front panel, knobs .State One binding -post strip, 1 x 10 x 3/16 -inch; visibility. Can be mounted on base - 7 x % City ...... One wooden baseboard, 13r/y x -inch; Write for Free Circulars and Full Informa, Two angle brackets, 1 x % -inch; Two tube sockets, UN -type. Station E LECT RkQ NEW YORK 326 METERS - 920 KILOCYCLES and W2%AL, 30.91 METERS is owned and operated by the publishers of this magazine vLECHTNEin you Barawik, the first and oldest radio Our Editors will talk to specialty house, offers you unusual SUPERIOR CONDENSERS service this year. Bigger stocks, several tunes every week - Best for power packs, power amplifiers, and quicker shipments, lower prices. f s. the countless uses to which high -grade Deal with an old established, reliable See yourÌewspaper ondensers are put. Conservatively rated, house. Get honest goods, honest service, and very reasonably honest prices. Barawlk service makes you for details dependable in operation, more money. Send now for big new Catalog show- ON priced, Flechtheim condensers have won for ing lowest wholesale prices. TUNE IN I,emselves an enviable reputation -a fact WRNY readily attested to by custom set builders, BARAWIK CO. radio amateurs and experimenters everywhere. Mall This Coupon Now for Free Rodio Guide Complete Line from 250 to 3,000 Volts D. C. Trite for New Catalog Name & INC. A. M. FLECHTHEIM CO., Addy... 136 LIBERTY ST., NEW YORK,N. Y.Dept.NR. /'lease say you saw it in RADIO NEWS www.americanradiohistory.com 486 Radio News for November, 1928 Facts About Transformers (Continued from page 444) '11* do not exist in the original signal, and nat- urally distortion will result. Make Your Set a Modern It can be seen that there are two oppos- A. C. Power Receiver ing values which must be accounted for in designing a distortionless transformer. 'l'he first clanger is having too low a primary impedance, and the second having too high a secondary. capacity. There are several ways of reducing the impedance of the sec- ondary winding so that a sufficiently large primary can be used. One of these methods is to use heavy insulation on the wire, and to space the layers of wire. This re- EwTone duces the capacity of the winding. The lowest frequency to which a per- New FOlk,OLD LIDIOS son's ears will respond is about twenty per second. The highest frequencies used in AMPLI PACK - with this Power Amplifier the average radio musical performance are A Complete A. C. Power Supply-"A" and "B" and "C"-Makes any D. C. Set about five thousand, although into an Ultra- Modern A. C. and "B" Supply the harmon- Receiver. Uses two 210 type tubes in Push-pull; or ics and overtones one of the new 250 type tubes. Power Amplification Camera - fidelity of reach frequencies higher like reproduction - gives perfect reproduction over the entire musical scale lowest notes clear and rich - music such than ten thousand per second. Broadcast range. as you thought your radio could never deliver! stations . are limited, by law, to a max- QUICKLY ASSEMBLED Three improvements -a new trans- imum of five thousand cycles anyway. In Youcanassemblean AmplipaCk easily FREE former principle, better use of the big order to in one evening. We supply complete power tubes, and stable plate and grid give perfect reproduction, a trans- layout diagrams. Simple to Install. Booklet voltage supply enable this unit to vastly former would have to respond to all Attached to set in three minutes. Con- better - of sumes no more current than an ordinary Write for our the tone quality of your present these frequencies. 50-watt light. Cool, quiet, dependable. new Free Book- radio. If only the second har- let-the latest word Available in semi- completed form . . . monic of the notes is reproduced, the tone ASK YOUR DEALER on Power requires but an hour Amplificut ion or so to put into Leading dealers can give operation . will seem quite natural, since the higher you full details and A. C'. Con- full, clear instructions .. and our simple assembly diagrams. version. works from lighting circuit ...coupon brings harmonics do not appear to contribute Don't be satisfied with out-of -date recep- complete details. tion-build an AmplipaC'k very much to the naturalness of tone. tonight! TRANSFORMER CORP. OF AMERICA R E M L E R 1428 -1432 Orleans Street, Chicago, III. CONSTRUCTION Manufacturers of the T. ('. A. Line of Power Transformers, Audio Transformers,!(Tokes, Power Packs and Power Amplifier Twin -Rotor In the construction of transformers, the Packs. CONDENSER secondary winding is usually on the out- side and the primary winding is placed For knife-edge tuning, use this famous next to the core of the secondary. 'l'he twin -rotor Condenser. Specified in] circuits -a* that demand extraordinary accuracy and cores in practically all the iron -core trans- efficiency. Price $5.00. formers are made up of a number of thin sheets of transformer iron or steel. In an REMLER audio-frequency D r u m transformer, these lam- inations are usually very thin, and care is D I A L taken to insulate them from each other. Rigid, heavy construc- tion, smooth, no back- The push -pull transformer is very much lash. illuminated. Drum like the straight step-up fifteen inches in circum- type, except that ference. Removable cali- the secondary is twice the size of the or- bration strips. dinary type and has a In Price $4.50 tap the center, connected Use the coupon befoul for full infor- to the "C -" battery, which mation on Remler Parts and Units. "biases" the grids of the push -pull power tubes. Similarly, the `B +" power lead is Remler Division. Gray A- Danielson aftg. Co. connected to a similar center -tap on 260 First Street. San Francisco, California. the Please Gentlemen: send me: primary of the push -pull output trans- Send postcard for new catalog and discount sheet. ...Ml the "dope" on the Power Amplifier. Hundreds of bargains in latest ...Bulletin service for set builders. former, or of the output impedance. Electric Phonographs, pick - professional kits and parts at liberal dis- ups, turn - tables. dynamic counts. See our new catalog Nance The auto-transformer contains one long for speakers. Shield -Grid kits. Television kits and parts. coupling impedances, shields. Short -wave sets. kits, parts. Address tapped winding, so that part of the winding and other parts. Power Packs. all kinds, includ- Van-Ashe has everything, at comprises the primary while the complete iitua 50 -tube and City State big discounts ready coil is used as the secondary. The circuits us circuits. tor12-hour shipment Do you build and sell sets? RN-11 I_ of the three general types of transformers are shown in Fig. 6. The output transformer is used to pre- (Dan-AsheRadio Co) vent the direct current applied to the plate 210 NDIAIOf!ST.%wish ST. LOUIS, MO. Electricity of the last tube from ¡¡" injuring the loud- Learn in Los Angeles. Thoroughly practical speaker course prepares young men, 18 and over, for winding. It also has another im- technical and executive positions. Unlimited portant use in balancing the output resist- opportunities in California for continuous ad- vancement. 32 instructors. Unexcelled equip- ance of the tube with the impedance of the ment. 23rd successful year. 17,000 active loud speaker. In order to get the most Neeestg oíie graduates. Highest Type Training. Recognized by Electrical Industry. Nominal Entrance undistorted output from a power tube and TO SET BUILDERS Requirements. Employment Service during and loud- speaker combination, the loud speaker atter training. California spending $100,000,000 Elections, foot. I games, big in electrical development. Large. illustrated should have the smile impedance as the National events will boost radio catalog sent Free, Postpaid. Dept. RN. plate circuit of the tube. The use of the business this year. Set builders will NATIONAL ELECTRICAL SCHOOL reap a rich harvest. Barawikservicewlll 4004 S. Figueroa, Los Angeles transformer with the correct primary and make you money. Everything in A -C seta, secondary impedances will satisfactorily parts, supplies. World's largest radio stocks on E.C.A. DRI -LINE 'A" Eliminator, 60 cycle. Ito V., output s hand. Orders shipped same day. Lowest rock -bottom Amiss, 6 V. No Battery- SILENT--$16.00; "8" Eliminators match these circuits when the tube and wholesale prices.i New Line R, 150 volt, 90 millamps, 4 tape, "C bias, with 280 do not Mail coupon for free Radio Catalog now bulb. 310.00: Model KW, 180 volts, 60 mills.. 5 taps. 280 bulb. speaker match directly. Canal Sta., $11.75: 5.0 V. tape for power tube filaments ' A-B-C" Elimin- BARAW I K C0.1112CHICAGO, U. S. A. ator, one 3 A., 6 V., side.180 unit, , "A" volta, 5 taps, 60 millampe. It is necessary to use a transformer with B: 4.5. 27, 40 V. CT DRI-LINE type, complete, 820.60. Mall this coupon for Free Radio Guide 2 amp. "Z" metal electrolytic charger. 86.50: 2 amp. DRI recti- a large core so that current in the plate fier, screw base, 82.25. Underground Aerials -no lightning Name hazard, 3.3.00; Shield grid sets, parts. supplies. Dealers wanted circuit of the tube will not be sufficient to Catalog 58. Above guaranteed 2 years, with 10 days' Vial 4Addna Electra- Chemical Co. of America. Indianapolis, end. overload the iron magnetically, as explained Ptease say you saw it in RADIO VEWS www.americanradiohistory.com Radio News for November, 1928 487 previously. In the straight output trans- former, two windings are used; primary and secondary, in 1 -to -1 ratio. The priiu- ary is sometimes larger than the secondary, since the impedance of the tube is usually Improve Your Radio higher than that of the speaker. This is es- pecially true of the electrodynamic speakers when a small actuating coil with a very low impedance is used. The push -pull out- With These New put transformer is constructed like the lush -pull amplifying transformer; here the HAMMARLUND PRODUCTS primary is tapped, so that the two tubes it the last stage may be coupled properly to the speaker. Shield -Grid Coils Exceptionally efficient low-resistance. space - wound, self-supporting inductance, 2 inches in diameter, for real results with shield -grid Smooth Power Dependent on tubes. A high -impedance primary with three taps Tube's Reserve for desired pick -up and selectivity. recent years the trend in automobile Antenna coupler and R. F. Transformers for I\ g use with either .0005 mfd. or .00035 mfd. design has been toward the use of en- condensers. gines having a greater number of cylinders Vertical mounting bracket for small space. Con- soldering and greater and smoother power. The venient terminals. fact that an engine can develop 75- horse- power or more or has the ability to drive a car at speeds in excess of eighty miles an hour is not the important consideration, be- cause few car owners ever have need to drive their cars at such tremendous speeds. The important fact is that a car which has such reserve power is capable of much smoother action at speeds of 30, 40 and 50 Knob - Control Drum Dial miles an hour than less powerful cars can Unmatched beauty and a mechanism that would delight a watchmaker. he such speeds. hope to at The control knob is uniquely planned to be placed In between the two extremes of the light in any position on the panel desirable for car of small power and the big cars of tre- attractsoe balance. Numbers and degrees on a translucent drum. mendous power there are a number of cars illuminated from the back by a small electric bulb. of varying degrees of power and smooth running at different speeds. For the Short -Wave Fan SMOOTHER PERFORMANCE Plug -in Coils, covering the short -wave bands from 8 to 215 meters. 'l'he same condition holds true in vacuum Extremely low resistance; widely-spaced plug - tubes. The maximum undistorted volume in terminals. .Adjustable primary held in any position by friction. which can be obtained from a 201A -type tube in the last audio stage is compara- tively very small. Better quality for any given volume can be obtained with a 112A tube. Still better quality for any given "Battleship" Multiple volume can be obtained by using a 171A tube with proper plate and grid voltages. Condenser If more undistorted volume is desired Leader of the gangs. Built for strength as well as beauty. Die-cast frame; Free - Than can be obtained with the tubes already moving rotor. Sections accurately matched mentioned, a 210 or a 250 tube may he used to within 34 of one per cent (plus or minus.; to provide undistorted reproduction at Made in 350 mmfd. and 500 mmfd. sixes, with two, three, and four gangs. volumes which would overload the 201.1, Recesses in the frame permit direct attach- 112A or 171A tubes. ment of new type Hammarlund Equalizing Bolo. Ï í In radio, as in everyday life, the same Condensers for utmost precision. principle holds true-"Don't use a. midget Write for literature on there and other new Hammarlund developments. ammarlund for a man's size job." PRECISION HAMMARLUND MFG. CO. 424 -438 W. 33rd St. New York PRODUCTS By- Passing the Grid -Bias Resistance many instances where a resistor is em- INployed for the purpose of obtaining "C" bias or "C" voltage from the "B" power unit, no by- passing condenser is employed. r BE A RAMO DOCTOR, J; This is an important oversight, since audio - frequency currents must pass through this radio part of the tube circuit, with the resistor if you are interested in radio, the quicker you decide to make your life work the sooner you will be assured of success and Big Money. offering serious opposition to their flow be- Don't stay in an overcrowded business ; get into radio. cause of its straight resistance, and, in the per week isn't unusual for the student "Radio Doctor" case of wire -wound resistors, the inductance $30 to $50 to earn during spare hours while learning. or choke -coil effect as well. In fact, there I NEED 1200 MEN AT ONCE FOR CHAIN SERVICE STATIONS is an appreciable loss of volume and tone Professional "Radio Doctors earn big pay and are in great demand. quality in the absence of a by -pass. $3.00 per visit is the usual charge of our licensed "Radio Doctors." There be an improvement in volume will "Have a licensed Radio Doctor fix it" is the slogan where our men operate. and tone when a by -pass condenser is WRITE TODAY FOR OUR FREE BOOKLET "WHY THE RADIO DOCTOR" shunted acróss any grid -bias resistor. This condenser should have a capacity of 1- or E.W. Parker, Pres. Radio Doctors, Inc., Dept. N2, Essex St., Salem, Mass. 2-mf., and may be of the low - voltage type. One with a rated operating value of 180 Insure your copy reaching you each month. Subscribe to Radio News -$2.50 a year Experimenter Publishing Co., 230 Fifth Avenue, N. Y. C. volts is satisfactory. f Please say you saw it in RADIO NEWS www.americanradiohistory.com 488 Radio News for November, 1928 Books wno Home should be without HOUDINI'S SPIRIT EXPOSES the hair, the eyebrows and lashes; and adding that extra pound or taking off excessive weight -all is covered. DUNNINGER'S PSYCHICAL ó BEAUTY SECRETS should be INVESTIGATIONS every woman's constant companion at the boudoir. Critics the country over By JOSEPH DUNNINGER have claimed that a fair price for a book of this kind would be from three to five In this remarkable new book the voice dollars. However, due to our unique of Houdini has been resurrected, as way of publishing, we are able to give though from the dead, and can be heard this book to you at the phenomenally to echo again in sullen denunciation of low price of- the ever- increasing number of spirit- ualistic mediums who, since his de- cease, have been parasitically bleeding the innocent public of its choicest pos- 50c sessions whilst posing in the sacrilegious Copy guise of the living dead. Per Joseph Dunninger, famous magician, Chairman of the Science and Invention Sold at all newsstands or Investigating Committee for Psychical write direct -112 pages -fully Research and the author of several illustrated -large magazine size notable works on magic, was a close personal friend of the late Harry Hou- dini. All the data appearing in this book was taken from the personal POPULAR CARD TRICKS notes of the dead magician now in the By WALTER B. GIBSON possession of Dunninger. These and the accompanying remarkable conclu- Pleasant Entertainment for All sions drawn from the various success- Walter B. Gibson has written what ful exposés of Houdini, together with the is conceded to be the most complete tremendously interesting revela- book of card tricks ever published. tions contained in Dunninger's Psy- There are literally hundreds chical investigations, make this of these a book clever little tricks. You need not be that all should read. Over 116 pages. a professional in order to work them Large 9x12 -inch size. out. There is no sleight -of-hand re- quired. You can do any of them with Only little or no practice. Simple to per- form- difficult to guess. Complete instructions - hundreds of illustra- 50c tions. Per Copy Once you have mastered a few of the tricks that this book contains you will At all newsstands become extremely popular -always or write direct entertaining. Imagine the fun you can have at a party. Just nonchalantly pick up a deck of cards and inquire if anyone has "seen this one." Then, BEAUTY SECRETS while all attention is focused on you, By EVA NAGEL WOLF do these tricks one after another to the admiration and wonderment of all. This book, by Eva Nagel Wolf, prominent editor of the beauty column This big book of entertain- of one of the leading women's magazines ment, fully illustrated -large and internationally known authority, magazine size divulges to seekers of beauty the true secrets of their type -just what is nec- Only essary to make themselves most at- tractive. "BEAUTY," says Miss Wolf, "is not difficult to obtain once you have learned the simple secrets of 25c type." It is the purpose of this book Per Copy to pass on to every woman these se- crets-to show her the quickest and easiest way to genuine beauty and at- At all newsstands tractiveness. or write direct There is nothing left unsaid -every phase of beauty culture is fully treated. The art of make -up, care of the hands, I 4 nos 0. EXPERIMENTER PUBLISHING CO,. Inc secs $1g'e9e,p5t9$Sss eo,ot4 230 Fifth l581,11" s9 Avenue Pybec gg S1oV1I 11ZZ óf ssE4 s New York, N. Y. gY ebooa9metsSpCsta .' . ,.. Ge state Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 489 Radio Wrinkles (Continued from paye 455) the size of drill required. The mounting screw for which a hole is to be drilled is OVe fitted into the various sample holes until the _ -. proper size is found; and then a drill which I:. will fit this hole may be found by referring to the marking in front of the hole or by experiment.- Contributed by D. Gooden- ough, Richmond, Ind. Townsend "B' Power Units, nmstbe good, A Neat Panel Light Now in Use - -tom Easily Made ANS who have radio receivers using They ARE good! Besides full tone, clarity and F the old -type non -illuminated vernier volume, you get the thrill of startlingly clear long - 1. distance reception. Never in radio history has any- dials are often faced with the problem of thing given such sensational results for such a low lighting the front panel of their sets. In price. UNSURPASSED QUALITY built in with this connection it should be pointed out that money saved by unified production methods and low an inexpensive yet neat panel light may be merchandizing costs. New thousands of set owners made from a standard brass drawer -pull, a learning amazing value of this Unit. lamp and 6-volt, 4- candle-power automobile Utmost economy and convenience. Plug into light a piece of sheet brass. socket and forget it. Delivers up to 100 volts on any The first step in the construction is to set on D.C. or A.C. -any cycle. YOU TAKE NO cut a mounting plate out of the piece of RISK. Sold on real GUARANTEE-it must sheet brass; the mounting plate should have satisfy or money paid us will be returned. the same width as the drawer pull and should be about one inch high. 'l'hree holes Fill in coupon and send with APPROVED must be drilled in the mounting plate; two SEND ONLY $1.00 only $1.00. Prove this marvel- and passed by the rigid laboratory tests have a diameter of 1/4 -inch and are located ous value to yourself. Use it ten days. Then if it fails us of "Popular Radio' in the lower corners, so that they correspond to do everything we say, return it and money paid receiver of your set. and "Radio News." to the holes in the drawer pull, and the third will be refunded. Make a REAL has a diameter of 11/16 -inch and is located in the center of the plate. Notches are From filed on opposite sides of the large hole, to This Month's Mail allow the pins of the lamp to pass through. The Eliminator received from you Next, holes identical with those in the plate about a year ago has proved a great success on my RADIOLA. are drilled in the panel of the receiver; the L. Newlin. Overland, Sto. mounting plate may be used as a template. Your Eliminator has saved me 520.00 in "B" batteries already'. Theodore Olsen. Ogden, Utah. Your Eliminator Is the most won- AUTOMOBILE derful power plant I ever sur. LAMP Picked up KRLO. Los Angeles. the first night. Never received this sta- tion with 3"B" batteries. Plenty of volume on loud speaker now. Pearl R. Duty, Mexico, Mo. Have been using your Eliminator for over a year and It has proved very satisfactory. MahlonMcFeaters.Johnstown. Pa. Have had your Eliminator for al- most a year now and have found a -- ÇUNTING PLATE ANEL LABORATORIES to be perfectly satisfactory. J. W. Nolan. Buffalo. N. T. Attach only 713 Townsend St.. NOTCHES $1.00 Chicago, III. My Eliminator has given first Gentlemen: Attached and 51.00 PANEL- class senice for two years. to this o o LIGHT Kindly send at once Townsend B" Socket I L/ J. A. Maithiot. Thorold. Ont. Coupon Power Unit, C.O.D. 85.85. plus postage. S I on guaranteed 10-day Free Trial. Eliminator received from you year Fig. 7. This bit of hardware will be a teat given addition to a home -made set which uses old- thaand n l atteries I used before. Name H. A. Hirschfeld. Lakewood. Ohio. -I' style plain dials. It will serte the purpose of Address illuminating the scale, as well as show that the I am very well pleased with Elim- set is turned on. inator bought from you year ago. Ed. F. Turns. Oklahoma Cy. Okla. I City Mate mm mm mm ma mm mm mm mm s' ...... After the holes described above have been drilled, the panel light may be assembled. First, the socket is slipped through the hole SEND FOR NEW RADIO in the mounting plate and soldered in place, WRITE BOOK - IT'S FREE! with the shell projecting through about 1/4- New hook -ups. This book shows how to make inch. The socket is slipped through the hole TODAY short-wave receivers and short-wave adapten. How to use the new screen grid tube in D. C. in the panel, and the lamp inserted in the Send for large, new il- and A. C. circuits. How to build power ampli- socket. To complete the assembly, the fiers, ABC eliminators. Up- to-the- minute lustrated Catalog "B -1," information on all new radio developments. drawer pull is placed in position and, to- showing the latest of It's free. Send for copy today. gether with the mounting plate, it is fast- everything in radio at KARAS ELECTRIC COMPANY the panel with two machine-screws. ened to 4038L1 -North Rockwell St.. Chicago. Ill. The panel light may be connected in the wholesale prices. filament circuit of the set so that it is con- Name trolled by the filament switch; thus making St. and No it serve as a pilot light as well as a panel City and State light. If, after it has been placed in serv- w. LAKE STREET, CHICAGO 4038 LI ice, it does not provide sufficient illumina- tion, the inside of the drawer pull should be painted with white enamel.-Contributed by Insure your copy reaching you each month. Subscribe to Radio News -$2.50 a year. 230 Fifth Avenue, N. Y. C. George Harvey, Lebanon, Ind. Experimenter Publishing Co., Please say you saw it in RADIO NEWS www.americanradiohistory.com 490 Radio News for November, 1928 Putting the Aerial in Shape Outstanding (Contiluled frolla paye 437) paper. Cut a slot half-way clown the paper and then curve the uncut part in the center. '2,000,000 Reception Bend the two tabs up at right angles and push them up under clapboards or shingles; Equip your Power Am- nail with a brad or two so that the guard will forni a roof over the lightning arrestor -and how the plifier with a POTTER as shown. This will effectively keep water CONDENSER BLOCK off the arrestor hut, if you are in doubt its to the latter's efficiency, buy a good one Hotel McAlpin and enjoy the pleas- that is hermetically sealed. A squeaking or sticky pulley can be lubri- is spending ure of natural, life- cated from the ground by tying a piece of it. like reception. New oil -soaked rag to the halyard and then rais- ing the rag to the pulley until the oil is tone brilliancy over squeezed into the wheel bearing. This is An improvement program shown in Fig. G and is a simple remedy. the entire receiving that will make the McAlpin a A STRONG CONNECTION NEW Hotel- inside and out range. Bass tones be- The proper way to keep the aerial and come full and rich lead -in in one piece is shown in Fig. C. Luxurious NEW carpets, dra- Pass a loop through the insulator and then in quality. twist this loop back over the aerial. A peries and furniture throughout solid hitch is made, and one that will not -bright, cheerful, interior dec- No. T2900 chafe away the wire. The twist is shown where one 250 oration - spacious, IMMACULATE in Fig. A, which illustrates the frayed con- rooms, type Power dition of a halyard which should by all all with modern tiled Tube is used oceans be replaced with new rope. Such baths- high -speed, electric, self - $20.00 chafings are caused by too -tight pulleys, leveling elevators - and a NEW No. T2950 rough trees, rotting of the rope, and like type of courteous, efficient hotel where two 250 causes. Put in new rope, all around, in type Power the fall and you will not find the aerial service that enthuses the most Tubes are used lying in the snow some nice morning after critical guests. $22.50 the worst storm of winter. Remember that an efficient aerial must We invite you to visit the not sway, POTTER BY -PASS CONDENSERS it must not leak its tiny power McAlpin and inspect the NEW Withstand High Voltages- to the ground in any way, and it must have a sure metallic path of low resistance over rooms - several of which are Highest Quality its entire length. Give it an overhauling already completed. this fall, and your programs will not DC Working suffer No. Cep. Test Voltage Price from neglect later on. All improvements are being A-1 .1 200V 160 $0.60 effected without the slightest in- A-2 .25 200V 160 .70 A-3 .5 200V 160 .75 terruption of service. A-101 .1 400V 200 .70 WRNY Television Programs A-102 .25 400V 200 .75 (Continued from page 415) FRANK A. A-301 .1 750V 400 DUGGAN .85 President and Managing At the receiving end the signals are Director POTTER CONDENSERS tuned -in in the normal manner but, instead Have Highest Efficiency- of being made to operate a loud speaker, H(l'l'FI. ' Longest Life are led after A.F. amplification to a neon - gas "glow -lamp" which is fixed behind a The Choice of Leading scanning disc identical in dimensions and MCALPIN Radio Engineers arrangement of its holes to the- one em- ployed at the transmitter. This disc also 9sk your dealerforfull information is rotated at the rate of 450 revolutions per ONE BLOCK from PENNSYLVANIA. STATION minute. The glow tube produces a pinkish POTTER MFG. CO. glow which varies in intensity in accord- B'WAY at 34th ST. North Chicago, Illinois ance with the electrical impulses fed it; just as a loud speaker produces sound in accord- ance with the variations of the current flow- ing through its windings. As the disc re- BUILD YOUR OWN volves, it allows the varying light of the EXPONENTIAL HORN glow lamp to pass through its holes, one 1 This marvelous 17.x21 -m. at a tinge, with the result that a continuous exponential horn with a 50,000 Feet 9 64m. air column can be series of 48 closely adjoining lines of light easily built by any ama- is, apparently visible teur of soft wood, all at once, to the of Radio Which produces the most onlooker. These lines are dark at each wonderful tone quality. 50,000 square feet of floor space We furnish you with point corresponding to one where the scan- in a large, s set of FULL -SIZED modern building de- PATTERNS, which have ning ray of light in the transmitter hits a voted exclusively to radio. Tre- been accurately and scientifically worked out dark spot on the subject, and light where mendous stock of latest kits, parts according to the exponen- a the and sets in improved designs and tial principle. Simply saw the ray hits light -colored spot. If out the wood to the size and receiving discs are in per- styles. Write for Catalog "B -1." and shape of the patterns transmitting and nail and glue to- fect step, or "synchronism," with the holes gether and you have the latest and in the receiver flashing past the glow -lamp MOST EFFICIENT TONE PRODUCER in exactly the same relative order that the Allied Radio Send 52.00 for a set of these full-sized patterns and holes in the flash past the arc CORP RATION complete lnstnetlons, or we can furnish you the COM- transmitter 711 W. LAKE STREET, CHICAGO PLETE KIT. rhirh includes the wood rut to fit, the nails. a recognizable image of the subject's the glue, our large-sized CONCERT UNIT. and full light, Instructions All complete with postage prepaid for $11.75 In face and form will he visible apparently on in the United States and $12.75 Canada. Insure your copy reaching you each month. Sub- RADIO PRODUCER COMPANY the surface of the disc facing the plate of Jefferson Bldg. Peoria. III. scribe to RADIO NEWS -$2.50 a year. Experi- 1245 the glow -lamp. (See pages 428 -9.) menter Publishing Co., 230 Fifth Ave., N. Y. C. Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 491 A series of eight 48 -line images per sec- ond is built up, in the Pilot system. Al- though it has been generally thought that at least twelve are necessary to create the effect of "moving pictures," this slower rate produces the illusion very successfully. As long as the subject does not move back and forth too quickly, his movements are re- produced smoothly and with a barely per- ceptible jerk. The images certainly will. satisfy the radio experimenters, for whose - sole benefit the broadcasting is done. IMPROVEMENTS UNDER WAY As this issue of RADIO NEWS goes to press, Mr. Geloso has not quite finished his auto- matic synchronising system, so this will be described in the next number. Briefly, his arrangement involves the transmission of a single strong impulse, at the end of each rotation of the transmitter's scanning disc. In the receiver, this impulse will kick over a relay in the plate circuit of the last audio-amplifier tube and this relay, in turn, causes a magnetic device either to accelerate or to retard the receiver's scan- ning disc. With one stabilizing impulse every revolution, the disc will settle down to per- fect synchronism with the transmitting disc; so that the received images will remain au- tomatically "in frame." Without some such Television- means of synchronization, and with only a variable -speed control on the scanning disc, At First Hand the images have a tendency to wander out Jules of view. For further discussion Verne, in his famous "Twenty seen it yourself and experienced the of receiver Thousand Leagues problems, see the article on page 422 of this Under the Sea," tremendous thrill which comes from number. written in 1870, accurately predicted seeing a weaving pattern of luminous television. Captain ' It must he understood that television to- Nemo, the mys- spots of light shift and whirl, then sud- terious owner of the great submarine, denly, as the revolving disk day is only for the experimenter, who will had worked reaches the find it more entrancing out the scientific applica- proper speed, resolve themselves into a as a scientific hobby tion of seeing at a distance. than radio broadcasting itself. Complete, clearly defined moving image which can be recognized foolproof television receivers for the public Many years have passed since the by everyone. This modern will not be ready for a long time but, mean- novelist's prophesy. miracle makes you think of nothing All that time so much as a great while, the home experimenter can contribute scientists and inventors have been Genie of the Arabian as much to the art of television as he did to striving to make television Nights forming itself out of a cloud of a reality. smoke from a the art of broadcasting in the early days, Every now and then for the last two or jar, just opened. from 1921 to 1924. three years you have probably met First -hand television is here and The true television broadcasting being some one who had a friend who had available to all. dune with the Pilot televisor, through witnessed television. Somehow or other National Company, Inc., has developed WRNY and W2XAL, must he distinguished you never saw the witness himself. new and better equipment for the con- from the "radio movies" being transmitted The information was always second- struction of short -wave receivers and by C. Francis Jenkins and also the "radio hand. audio amplifiers of the type required movies" recently demonstrated by the West- for successful, experimental Now we have television inghouse Company, described elsewhere in advanced. Television is reception. Write today for Bulletin these pages. In the latter forms of broad- being accomplished. You may have No. 128 -R. F. casting the pictures on a roll of motion - picture film are transmitted, not the images of a living person. Radio movies, however, offer also an extremely interesting field and, NI z TIONAL fortunately, the owner Of a 48 -hole tele- vision apparatus can reproduce the ,Jenkins RADIO PRODUCTS NATIONAL CO pictures also. INC w A READY Pets MALDEN MASS John Geloso, the chief engineer of the Pilot Electric Manufacturing Company, and Improves any set. the man responsible Neat, compact, durable. for the design, con- Easy to install. Moderate struction and successful operation of the in price. Pilot -WRNY television apparatus, is only twenty -eight years old and has been in the United States only four years. He was born in South America, but has spent most of "The Perfect Contact Radio Ground" his life in Italy; is a graduate of the Uni- Patent Applied For versity of Genoa, where he studied electri- PER -CON MFG. CO. Richmond, Indiana cal, mechanical and naval engineering and, before coming to the United States, he fol- lowed the profession of a naval engineer. Mr. Geloso has been with the Pilot com- SUPER-DAMOHM pany for the past three years; and five Radio has been changing sofast months ago he was assigned by Mr. I. Gold- lately that it's hard to keep up berg, president with it. Barawik's Big Radio Guide of the company, the stag- will keep you posted on the newest gering designing (ACTUAL,SaZE) wrinkles. Thousands of task of a practicable tele- of illustrations SOO to 5,000.000 ohms new ideas. vision transmitter that would stay within save moey. Send for free copy now. distributed capacity and indue :wee practically negligible. The 5,000 cycles. Within five [hays from the time most accurate and emcient resistance unit known to radio. BARAWIK Irrite for book'eI D. DAVEN CORPORATION. Newark, N.J. CO,2 CaCAGO. U.e Please say you saw it in RADIO NEWS www.americanradiohistory.com 492 Radio News for November, 1928 he obtained suitable photoelectric cells, he had a complete transmitter and test receiver CARE SHOULD BE working in the Pilot laboratories in Brook- lyn and, the first time he turned the ap- TAKEN paratus on, a crude but recognizable image appeared in the receiver. IN CHOOSING With a regular television service now un- der way at WRNY, Mr. Geloso is perfect- LOUD SPEAKER ing numerous details of the system, such as automatic synchronization, proper coñtrol and mixing of the outputs of the photo- Acoustic Engineers Recommend Cut out squeaks and electric cells, the design of a small motor Use of Book by Well -known for the receiving disc, etc. Further news for squawks with of his accomplishments will be published in Authority Instruction forthcoming numbers of RADIO NEWS. Wirt Static Filter "The necessity for care in choosing a loud Only $2.25. Guaranteed to filter out prac- speaker cannot be over-estimated," say tically all usual static noises-or get your Reception of the Jenkins acoustic engineers. A radio is but the vehicle money back. Sharpens selectivity. Sweeten s used to bring in broadcast entertainment, the tones, including high soprano. No distor- "Radio Movies" tion; volume stays the same. Fits any A -C true reproduction of sound depends almost or battery set, anywhere. Easy to install (Continued front page 420) entirely on the speaker. It follows, if the and adjust. Get one! loud speaker does not meet the requirements SIMPLE SYNCHRONISING DEVICE of the receiver, reception will not be at Save Your Tubes A very simple and practicable method of maximum. Consequently the entertainment scanning with Wirt Voltage Regulator. A -C tubes adjusting the speed of the disc of of the listener-in is often unwittingly spoiled and sets do best on 110 volts. Normal a television receiver is suggested by the by failure to recognize the importance of a voltages are higher and there are frequent Jenkins Laboratories in a recent bulletin good speaker in getting maximum results current "surges ".Wirt which they have issued to radio experi- from his set. Regulator admits menters. The idea is to support the disc con only an even, con- on any suitable set of bearings, and to drive Education of the public in speaker -, stant flow into it by the friction of a small wheel (attached struction and design is necessary according to the set. Saves these experts. They recommend "HOW TO tubes and set to the shaft of a motor) pressed against its from being surface. By varying the distance between BUILD MODERN LOUD SPEAKERS," burned out. Sup- the friction wheel and the center of the written by Clyde J. Fitch, as being the most presses line noises, disc, the experimenter can find a setting at efficient source from which this information too. Only $2.25. which the disc turns at exactly the same rate may be obtained. The book is written in a of speed as the transmitting disc. At dif- style that is not only tremendously interesting Lightning Protection ferent positions on the radius of the disc, but also decidedly easy to read. "HOW TO the circumference of the friction wheel i Wirt Lightning Arrester safeguards not BUILD MODERN LOUD SPEAKERS" is bears different "reduction- ratios" to the cir- only the radio set, but all its parts, too - complete of its kind avail- so, naturally, it drives the most treatise and, in any weath- cle of active contact; er. Gives peace of the disc at different speeds. (See page 420.) able. It thoroughly explains every known ®® of speaker and gives full instructions for Vlair mind during elec- In this arrangement, the driving motor type trical storms. Easy if should be run at its natural speed, without building. It is well to remember that the to put in place. Stays is not used the enthusiast rigid. Good look- being 'controlled externally by a rheostat. proper speaker ing. Only $1.00. Once the correct position has been found, leaves himself open to all manner of distorted the motor should be clamped in place, or at reception. Crackling noises, fryings, whistles Any radio dealer can get you Static Filter least the position noted accurately so that and squeals -these disturbances, often laid Regulator, and Lightning Arrester. Or send check -we'll ship postpaid by return mail. the proper setting can be made quickly. to the set, can in reality usually be traced to Using a 48 -hole disc, a television experi- the speaker. Also the fact that a speaker WI R7- OMIPAW( menter can find two positions of the motor, works well with one set and not with another for 900 and 450 revolutions per minute (the is no reason to lay faulty reception to the set. Philadelphia, Pa. distance from the 5221 Greene Street former will be at half the "So," the experts point out, "you must under- center, except for slippage), and then will Makers of "Dim -a -line" and "Dim -a -Lamp" the speaker if you are to receive the be able to receive either the Jenkins or the stand WRNY broadcasts, respectively, without maximum results from your receiver." other change. This scheme is considerably "HOW TO BUILD MODERN LOUD cheaper and more flexible than one involv- SPEAKERS," by Clyde J. Fitch, is not only ing the use of gears, which require accurate the best source from which to obtain this Set Builders mounting and alignment. essential information, but also probably the If you already have a scanning disc cheapest. Complete, dependable data on \'t rite us for new illustrated Cata- mounted on a motor, use the latter merely every speaker known in radio -full instruc- log "B -1," containing all the new as a support for the disc and drive the disc tions for building. All this for only twenty - and popular kits in radio. Our of 1/20- or tremendous stock enables us to itself with another small motor five cents, the price per copy of "HOW TO give you immediate service on 1 /16- horsepower, say. A suitable mechani- BUILD AIODERN LOUD SPEAKERS," used in a all radio supplies at wholesale cal arrangement of all the parts by Clyde J. Fitch. Mail this coupon to television receiver is shown in the prices. complete Consrad Company, Inc. 230 Fifth Avenue, on page 420. The details are illustration Y. all obvious; the actual dimensions of the New York, N. Allied/Radio wooden members supporting the motors and CORP RATION the glow lamp will depend, of course, on the CONSRAD COMPANY, INC., 711 W. STREET, CHICAGO LAKE particular apparatus the individual experi- 230 Fifth Avenue, New York, N. Y. menter has on hand. Gentlemen: .. Enclosed find twenty -five cents. for which please send DESIRABLE me a copy of "How to Build Modern Loud Speakers," e. CAREFUL ADJUSTMENT by Clyde J. Fitch. 1?ad14 A -C. ari The friction wheel may be made of two witbradio'e newest'done- Ree »po of new devel- tube, dynamics, television,[core, e .has k rit cut from an old inner tube; radio down Barawik of rubber Name RpD10 te. Since vw e.t discs bitter e ke. better \ L,LDt añead by Ráéio Guiáe le 3 inches in prices Barawik'sBfa New should be about DA or it they wholesale discountsd to set builders, deal - diameter, and will work best if clamped be- Address ors and ts. brass or fron flanges, one of BARAWIKCO.. 211DD Centtst...Chiugo.USA tween two -FREE which fits over the motor shaft. The flanges City State Please say you saw it in RADIO VEII'S www.americanradiohistory.com Radio. News for November, 1928 493 should be only about one inch smaller in diameter than the rubber discs, in order to prevent the edges of the latter from folding over when they are pressed against the scanning disc. It will pay the experimenter to have these flanges turned out for him by the local ma- chinist, or by the garage man if he has a Faithful R adio Se rvants lathe; they will cost only a dollar or so, and will be well worth their price. Unless these ELECTRAD RADIO CONTROLS flanges fit the driving motor's shaft smoothly, the rubber discs will wobble and They are the guardians of your radio -protecting it will make the wobble against fluctuating voltages, controlling volume smoothly. scanning disc also. eliminating oscillations- assuring the highest order of Use any small induction or synchronous performance for whatever radio function they are used. motor that is obtainable. Universal motors Electrad specializes in a complete line of such which spark excessively at the commutator resistance controls for all radio purposes including Tele- should be avoided; as this sparking will af- vision. They are obtainable at your dealer's., fect the neon -gas glow -tube and cause spots to appear in the images. However, this in- terference can generally be eliminated by a TRUVOLT pair of ordinary 0.5- or 0.1 -mf. by -pass con- U.S. Pat. 1676869 and Pats. Pending I densers connected in series, and across the ALL -WIRE RESISTANCES motor brushes, with the center connection Admittedly superior for control of voltages in II- of the condensers going to the ground lead Eliminators. of the radio set. 'l'ruvolt Variables simplify It- Eliminator construction by eliminating difficult calculation and making all Naturally, the only way to determine the adjustments easy. Truvolt Fixed are adjustable to different set values by the use of" sliding clip taps -an proper position for the driving motor is to exclusive Truvoit feature! tune in the television or "radio- movie" sig- nals from WRNY- W2XAL, or from 3XK (the Jenkins station on 46.1" meters), and to PHASATROL turn the adjusting screw shown in the dia- Reg. U.S. Pat. Oa. grams until the images appear. A little A True Balancing Device for Radio patience is required for this adjustment; Frequency Amplifiers if you do not obtain pictures on the first Licensed by Rider Radio Corporation trial, again. try Phasatrol is an unusually efficient device for controlling radio frequency oscillations and thus eliminating the dis- turbances to reception which they cause. Adapted to any type of receiver using R. F. amplification. A wonderful improvement for the new A. C. circuits where the On the Short Waves elimination of oscillations is often a serious problem. Price $2.75 each. (Continued from page 457) SHORT WAVES AND BROADCAST El LISTENERS ROYALTY Inc. /' ept.N -ll, Editor, RADIO NEWS: Exclusively Licensed by Tcehnidyne fa. 175 Variek The letter entitled "Short-Wave Reception on a Corporation Under U. S. Patents /sf, St., New York Nos. 1593658, 1034103, 1034104 Standard Ultradyne" in Raoul NEWS for Septem- ber (page 254) deals with a matter that is surely VARIABLE HIGH /4t' dmsriiihrendirme not new to anyone who has ever operated a super - tars on the following RESISTANCES / /"1C products and put me het within a few miles of an amateur transmitter. on your mailing list The fact that most any superhet (and particularly Recommended wherever a /34.° for similar literature. the Ultradyne) has this failing is never mentioned variable high resistance . Generai circular. TOaatrol Volume con- in the "how -to- build" articles, probably due to the free from inductance and //4sß -- effects is need- commercial slant of these articles. In many in- Phasatml9. ed.Unusuallyacenrnte /4 Royalty Variable stances the publishers seem Resistors. to deliberately connive and dependable. The /4Q . ."Electra(' Control Manual" with the advertisers to "work" the reader by failing range of resistance /A Pape to tell the whole However, the covered in one Srse EÌimmotor IBbg) 1 story. tendency of / Build?' enctose lOcfsg matting) the Ultradyne to its turn of knob. 11 jet. suffer from own oscillator am Particularly interested In harmonics types to meet was mentioned in Q.S.T. at least three every radio /4d' years ago. purpose. Nano With my own superhet (just the ordinary name- /Fi Addre.. less standard variety) I found some time ago that / <'üy . . Stat' it was the third or fourth oscillator harmonic that was heterodyning the short -wave signal to the fre- quency of the intermediate transformers: and thus permitting the short -wave signals to "come through" on broadcast settings of the oscillator dial. Practically every superhet owner in this vicin- ity has the same complaint. There are a number of methods of partially over- ELECTRAD, coming the difficulty: (1) Suppressing the undesired S.W. signal in the loop by mounting a tunable absorption Circuit on the loop frame. (Who ever heard of a real superhet that required more than a loop for coast - to -coast reception ?) This handy book should (2) Suppressing the undesired oscillator har- monic by surrounding the pick -up coil with a tun- go with every Radio ! able absorption circuit. It Is concerned with radio Nye Honk -ups. This book (3) Suppressing the S.W. interference at its parts -their functions - shows how to make Short -Wave where they am and source by applying the homeopathic treatment ( "like - Receivers, and Short - Wave their names. It gives the Adapters. cures like to the who symbols used In radio ") amateur operator persists How to use the new screen - ill going on the air before 11 m. or a Sunday hook -ups. so that You grid tube p. be able to read any in D.C. and A.C. afternoon while the rest of the city is enjoying the dwilliagram understand circuits. and Haiv to build Power broadcast programs. Most anyone past the radio it. It discusses air waves Ampli- takes fiers, and Aile Eliminators. Up- -the aerial -then to- the kindergarten "knows how." You through every radio -minute Information on Only "one -way" communication soon sends the part -and finally the all new radio developments. actual reproduction of Set Builders. Fans, Dealers, troublesome operator to bed and permits the rest sound. send for it today! of the city to again turn on their receivers. An This Is a book that KARAS ELECTRIC COMPANY 403SL2 even simpler way is to make friends with the fam- will give you a full under- 403$L2 N. Rockwell St., Chicago, Illinois ily next door to the "source" and arrange with standing of your set. . Please send me sour Free Book! them to turn on the vacuum sweeper upon phoned ALL ABOUT RADIO PARTS Name request. they own a receiving set the phone x inches, fully Illustrated If 555 745 Address call is unnecessary. Get It from any newsstand or direct THE CONSRAD COMPANY- INC. Cite (4) It has been claimed that reducing the oscil- 230 Fifth Avenue New York City State P(ea.te Sav 1'oIf saTt' it in RADIO N F. IV .\' www.americanradiohistory.com 494 Radio News for November, 1928 lator plate voltage will reduce the intensity of the harmonics, but it has been the writer's experience that the fundamental is reduced in the same pro- portion. kosieWe (5) The shorter the wavelength of the inter- mediates, the less the likelihood of annoyance from short -wave stations. This is a strong point in favor Positive of the "neutrohet" recently described in RADIO NEWS, the description of which was indeed a genu- Voltage Control ine "how -to- build" article-an article written for the benefit of the reader rather than the advertiser. for Radio Power Units W. J. IC., Salina, Kansas. (The above calls for comment. The short waves are now being drawn upon The new Centralab Heavy -Duty Po- by not only the ama- tentiometer is all wire wound and will teurs, for whor the writer of the above "has it in." carry the entire output of any "B" but also governments, commercial radio services, power device with an unusually high public utilities, broadcasters, televisors, and others. margin of safety. The high frequencies will be used at all hours of Resistance re- the day and night, extensively; the entire wave- AVIATION mains constant at range, from the highest to the lowest, will be any knob setting. tilled. The broadcast listener must therefore soot so that panel or EVERYBODY'S AVIATION knob can be be prepared to obtain a set which will twee ex- GUIDE is marked in volts. clusively to one tcavcrange, not merely one channel a complete discourse A single turn of in each range: for the ether will be full of har- on practical aviation, by MAJOR the knob will monics as well as harmonics. .4s for the ama- VICTOR W. PAGE, one of the give full varia- teur, the law which requires him to keep within tion. his own definitely, and now more narrowly lim- leading men in the field. Unlike H a s sufficient ited channels, also forbids and provides penalties current carrying capacity to most books of instruction, permit for the creation of intentionl interference in the < shunting a low resistance value across EVERYBODY'S the "B" power unit to obtain constant manner prescribed as his third recommendation by AVIATION voltage regulation. A sufficient cur- our correspondent. Our advice is, DON'T! - GUIDE is written in a unique rent load is maintained throughout the EDITOR.) resistances to reduce the rectifier volt- question and answer fashion, age to workable pressure. even though which makes the subject far set is not connected-an insurance NO SHOCK AT ALL -IT'S JUST LUCK easier to study against filter condenser breakdown. Editor, RADIO NEWS: and a great Write for folder giving details I have built the "Junk Box" receiver described deal more attractive as an in- in RADIO NEWS for July (Blueprint of this circuit. No. 58) and struction course. this is to prepare you for a shock. The set was < Resistances: 2,000, 3,000, 5,000, 8,000, built as described about three weeks ago and is This book was recently published and 10.000, 15,000, 20,000, 50,000. Price, $2.00, used very night with an adapter plugged into a is absolutely up-to -date in every way. at your dealer's, or C. O. D. two -stage amplifier. I get practically all the short- It has had very favorable criticism wave stations using phone and code. But every throughout program is clear of static. I have tested the set country-wide aviation cir- cles and has been highly recommended CENTRAL RADIO LABORATORIES during thunderstorms; and music, speech or code came through without the crashes usually heard by all those in a position to pass 20 Keefe Avenue, Milwaukee, Wis. from lightning. I want to know if this is usual j udgment. or unusual for a short -wave set. This is a pretty broad statement. I expected We list here the contents in order that less static on short waves; but cannot understand you may see for yourself how com- why I get none -not even lightning. pletely the field of Aviation is covered. L. E. PLATT. (Short waves are usually freer from static than Contents: the longer ones; wherefore the growing demand for short -soave stations and apparatus, especially Early Aeronautic History -First Flying in the tropics, where static was invented. Machines -The Atmosphere Except Forms of Aircraft- Airplanes and Air- for local disturbances, therefore, there is less static; ships DItLSNLIt but our correspondent i.s highly favored if he hears Lighter- Than-Air Craft -Balloons and Mont at all. He fails to state what his antenna Dirigibles SHORT-WAVE CONVERTER system is.- EDITOR.) How An Airplane Flies- Elementary Aerodynamics Airplane Parts and Their Functions WAVE- Fuselage Forms and Landing Gears COMPLETE A SHORT-WAVE SET WITH Wing Arrangement and Construction LENGTH LARGE CAPACITY Power Requirements, Engine Types and RANGE Editor, RADIO NEWS: Engine Location 15 to 550 $ 22.50 Enclosed find a diagram of the short -wave set Aircraft Propellers. Design and Applica- Meters I have constructed which I find to be quite effi- tion (SPECIAL) cient, 'and has some new pointers. Airplane Equilibrium and Control First, I use Official World and .American Air Records as a regeneration control, a resistance of 200 ohms May be used with any type of broadcast receiver. to 30 megohms. This will have to be of the Easily connected in just a few moments' time. No non -microphonic type and also be noiseless over complicated wiring. Simply plugged into the the entire tuning range. The one used in my detector socket in the set. Covers the entire range set was manufactured by the Pilot Electric corn- of wave lengths from 15 to 550 meters. Maxi- : mum satisfaction from top to bottom. Don't miss NZ<..: : the excellent programs now being broadcast on EVERYBOGY\`. the short waves. Get a Dresner Converter. Five AVIATION interchangeable coils furnished with each unit. If your dealer can't supply you, Send Money Order Direct and we will ship P. P. Prepaid. Gaaranleed. Price (When ordering unit, be sure to specify whether it is le be used on A.C. or D.C. set.) DRESNER RADiO MANUFACTURING CORP. 640 Southern Boulevard New York, N. Y. N: Over 248 pages Beautiful red cloth binding -Title in gold tgo; Nis Book, Replete with illustrations /3ringsl7ealers WRITE DIRECT TO BIGGERPROFITS CONSRAD CO., Inc. 230 Fifth Ave. New York , N. Y. Matchless bargains In radios mid accessories. Full line of Sleeper BrowuingDrake. Carter. C tah. Tower5peakers. Temple, \IaJestic, Nadel. (..E. Tungar. Burgess. Jewell. Belden. Cunningham tubes, The hook -up of .)Jr. D'.4ngelo's set. A fixed nationally advertised parts. storage batteries. chargers. etc. Big regeneration condenser is employed, with a CONSRAD COMPANY, Inc. ones who can sell sales Quick. 230 Fifth Ave., New York, N. Y. opportunity for live radio. Double variable resistor as a control. Use your letterhead. Exclusiv: territories open. ct-\OW! Gentlemen: Mildly send me one copy of your NEW ENGLAND MILLS COMPANY book, EVERYBODY'S AVIATION GUIDE .PZM,tbutorr of :Nationally .Adrerttsed Radio Lines Enclosed find 02.00. Dept. R200 051-5S Washington Blvd. Chicago, III. pany. Second: Instead of the usual 7 -plate tun- ing condenser, a 23 -plate De Jur straight-line con- Same denser of .00035 capacity was used. This gives me good volume with oscillations over the whole RA010 FUSE at with little hand capacity. Add., PREVENTS DAMAGED TUBES,COILS, dial all wavelengths, Third: Although my aerial wire is well over 200 B BATTERIES AN0 ELIMINATORS. 254 feet, no condenser is in series with it. City State OAK PARK MEG CO BOX OAK BARK,ILL. 3e* sasef too The following are specifications of the parts Please say you saw -it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 495 used: LI, antenna coil, 8 turns of No. 18 D.C.C., space -wound '' -inch apart, on 4 -inch tube for all wavelengths. Up to 50 meters, grid windings, 3 turns of No. 28 wire on is-inch tube. Tickler coil same as above, wound directly over the other. From 50 meters on, 9 turns of No. 20 wire NORDEN -HAUCK spaced 1/16 inch apart for secondary, and 8 turns for tickler on a 3 -inch tube; Cl, .00035 -mf, condenser; NEW 8 TUBE C2, .0002 -mf. (This must be accurate); C3, .0002 -mf.; C4, .0001-mf.; Rl, from 200 ohms to 30 megohms; AC ELECTRIC MODEL R2, 6 megohms; L2, 140 turns of No. 26 wire on a 1 -inch tube, 4 inches long. 67 volts on the plate will be needed for wave- FOR lengths up to 50 meters, Beyond that 22 volts E will be required for the correct operation of the set. The tube is the usual 201- \. The following stations have arrived regularly: 1929 2NAL, 2XAD, 2XAF, 2XE, WI.W. KDKA, WHAM, CITY, 5S \Y, PCJJ, 3XL. and numerous Size 8 -11x22 others. Harmonics of \\'A.\T, WIIN and \CTFF and others were heard. Amateurs in Montreal, Weight 35 St. Louis and California were also logged. lbs. I would like to hear from builders of this set, and hope this information will be of interest to Wave length T your readers. EUGENIO DAwGELO. range 200 to 69 -71 Dundas St. WP., Toronto, Ontario, Canada. 550 meters. '\ THESE FUNNY WAVES The Norden-I hoick Eleetrophonic is an entirely new and superior broadcast Receiver operating directly from house current. is well handsomely Editor, RADIO NEWS: It built, finished and com- pact. Truly it represents the highest type of efficiency obtainable in point of range, Many thanks for blueprint No. 58, for the selectivity and simplicity combined with utmost quality of reproduction. "Junk Box." I have just completed the set and given it a few days' tryout. Following are the results to date: 2XE, good; very clear. 10 OUTSTANDING FEATURES 5SW, at times very clear, but much troubled ELECTRIC. The Electrophonic, is all electric operated and self-contained. No Elimi- with body capacity. Better at 7 than at 5 p. m. nators or batteries whatever. Employs standard Radiotron or Cunningham alternating 7. I' "Big Ben" comes in fine at current tubes. 2XAL, not so good. Music difficult to follow. CIRCUIT. The Electrophonic employs an 8 -tube circuit; three stages direct tuned . Much distortion-still, many- thanks for an an- radio frequency amplification fully neutralized, detector, and three -tube power audio nouncer who announces the station often. At least amplifier push -pull type. one gets a chance to locate the station if he misses SHIELDING. The Electrophonic is totally shielded. Complete inter -stage shielding permits high amplification not obtainable otherwise. H the letters, with the sentence which follows: "RADIO NEWS station, located at the Roosevelt SIMPLICITY. The Electrophonic has but one control for wavelengths, one control Hotel." for volume. Illuminated drum dial calibrated in degrees and in kilocycles. 2XAF, heard once, when everything said and SENSITIVITY. The Electrophonic has carefully balanced radio frequency tuning done was very clear. circuits which with superior quality of materials and workmanship combine to make the Norden -Hauck Electrophonic a long distance Receiver. KDKA, at 42.95 meters, better reception than SELECTIVITY. In Electrophonic o on lower channel. the total shielding and carefully balanced circuits and quality permit unusual selectivity so necessary in congested districts. MAN' cernes in very clear. Besides these stations, I have heard, although QUALITY. The Electrophonic is of the highest quality of construction and design throughout. Comparable only with costly custom built Receivers. very indistinctly, the gym classes between II and IST FINISH. The Electrophonic has a exquisite solid mahogany cabinet, 12 a. m. of WMCA; also a religious service from brown finish. Heavy cast bronze escutcheon plate and tuning knobs lend to the rich appearance of (I believe) WAAM. The singing was so dreadful the Receiver which will fit in any surroundings. Cabinet high French polish and full that I tuned out without attempting to get the piano hinge. Back removable and ventilated. call letters. Now, this morning. I heard a band GUARANTEE. The Electrophonic material and workmanship are fully warranted playing (very fuzzy) about \V LW's wavelength. against any defects whatsoever. I Is it possible that these were the harmonics of PRICE. The Norden -Hauck Electrophonic Receiver is moderately priced at $125.00. W5113Q, Brooklyn, as the call sounded like these Packed for shipment, letters? (It is quite possible to get a harmonic, say the fourth, of a broadcast station in this manner; in the station's immediate field, harmonics as high as the thirteenth or fourteenth may be detected. The oddity of short -wave reception is List Price '12500 f.o.b. Phila. thus indicated; our correspondent, living just across the city line of New York. gets London easily, Pitts- COMPLETE illustrated literature gratis. Write, telegraph or cable today. burgh and Cincinnati clearly, Schenectady with difficulty, and New York City stations hardly at all. .I fern miles closer, he would be in their inductive NORDEN-HAUCK, INC., ENGINEERS field; and a few miles further away, he would MARINE BUILDING, PHILADELPHIA, PA. probably be unable to net them at all. The quality, also, of the ground wave is undoubtedly affected Builders of the Highest Class Radio Apparatus in the World. by numerous reflections at short distances in the city.) I have not as yet succeeded in getting a squeal from the largest coil, No. 5. I propose rewinding. I have two aerials, one outdoors, and one indoors, strung under the room. Reception seems about GEARS the same with both; but by disconnecting the All kinds -Small ground wire last night, while listening to WL\C, IECTRicintr&tullgd The most accurate made and IN A FEW WEEKS improved very much, and static and reception was prices reasonable. We carry a Learn with real tools on real equipment. No hum notably diminished. complete Ilne of gears In stock no lectures. for I built this "Junk Box" set after working long Immediate shipment. Can Sweeny's SHOP PLANs stem of training real also Quote on special gears of electricians in shortest posylble time. 90 days' tmining fits you with the hook -up which appeared in RADIO Neuts a0 kinds. Send us your Inquiries. for a big-pay lob at S50 a week. and up. Write for big electrical last October. With that I got PCJJ once at Write for Catalog 40 book FREE-also remarkable tuition otter. which Includes Chicago FREE E. R. fare. I guarantee satisfaction or 2 the stations, when could Stock Gear Works money back. a. m.; the rest of I l0S So. Jefferson St., Chicago make them out, were very poor. I have certainly McSWEENV DEPT. 7765, CLEVELAND, OHIO got better results with the "Junk Box." Once again, many thanks for the hook-up and blueprints. I trust you will give us more short -wave data. Per- haps your expert could give us a few tips as to BUILDERS/- howls body capacity in the DEALERS L. SET how to get rid of and stock of nationally known parts FREE RADIO CATALOG "Junk Box." Complete and accessories. Send for illustrated cata-' Sine, the down of Radio. Barawik hoe been known the world O. STANLEY 1IEATON, e headquarters gor radio set builders nod fana log and discount sheet. Hera undo one r L everything you need -set,. parte. Bandmaster, Leake & Watts Home School, euppiie,- thousandaoiproduct, -read o,hiptoyouthe Radio Exclusively Since 1921 same day your arrives. Barawik price. you Yonkers, X. 1-. orderservice Pares time. Barawikwee ehandise slave ,ter (The best way to reduce body capacity in this CLARK & TILSON, Inc. customers say. ' BarawikBa is Best." Let us send set is to use extension handles on the condenser New York ou` the Barawik Book tr.- and prove it to l2.2 CHAMBERS ST. Yourself. 211 E CANAL STA.. usually a to regu- dials. Howling is matter be The Nationally Known House BARAW I K CO. GN6AGO. U. Si A. lated by better tuning: EDITOR.) Please sae you s'nta it in 2.If)fo NEWS www.americanradiohistory.com 4'!(, Radio News for November, 1928 SOME DO NOT Editor, RADIO News: 1929 TYPE To the many thousands of short -wave set builders who have been as unsuccessful in logging far distant foreign stations as I have, I would like to A. C. give a "handshake." These boys need more en- SHIELD GRID couragement than the successful ones do praise. I, for one, have built every short -wave receiver 'Radio Educator that has appeared in RADIO NEWS, as well as BROWNING -DRAKE others. For six months I plugged faithfully away, A P.t adini; Course never' "getting beyend New York, hearing 2XAD, IlÄ Fi\r SaOks 2XAF, \VGY, once in a while WLW and \VABC. The "R.F. Short-Wave Receiver" was built, which was the best one for volume and quality of reception. The radio frequency was not success- ful for me; this was removed and a B -T detector unit mounted. This was a great improvement, but still no foreign station. I have corresponded with several short -wave set builders and have tried their suggestions -but to no success. For the amount of blueprints dis- tributed by the RADIO NEWS, the number of suc- cessful "foreign getters" must be very few in comparison. A combination of I have spent several hundred dollars, at least true single three hundred dollars, and still I have lots to control, without trimmer or learn and receive. I eventually drove a fifteen - variometer, together with A.C. foot pipe in the ground and by using the ground for an aerial and no ground, I have been able to shield grid operation, mark this tune in every Friday night PCJJ, which is barely as the season's foremost Kit. audible in the p!lones. Occasionally it can be Remember more heard in the loud speaker. One evening, between that Brown- 6:30 and 7.30 E. S. T., I picked up a foreign Price $1.97 ing- Drakes are built than any station on the phones that sounded like German. other Kit assembly. Full scale This was on about twenty meters. One afternoon at two I .picked up a phone conversation in Italian constructional data free on at about 17 meters. request. This is the limit too my success. \VGY and A KDKA come in with enough volume to be heard a block away -but no foreign station calls at my Complete Parts -$59.45 house. I have just completed another set in the past RADIO Some territory is open for dealers two days, using a CX -322, screen -grid tube as a and distributors to handle Brown- radio frequency amplifier. Last night was the first ing -Drake factory -built receivers. time I ever heard PCJJ on the loud speaker with EDUCATION Write for franchise information. sufficient volume that I did not have to strain every nerve. On the phones it was very fine. IN 5 VOLUMES A local short-wave expert is now worl:ing on Browning -Drake my set to eliminate body capacity. He has a set Brighton, Mass. such that you can put your hand on the coils, tubes "THE RADIO or inside of the coils and no body capacity is pres- ent nor does it reduce the volume. He uses three EDUCATOR" tubes and gives more volume than the R.F. re- ceiver with push -pull amplification, day or night. Theory, Design, Construction, By the elimination of the body- capacity effect he increases his volume more than double. Operation and Maintenance Let's hear from some of the "failures" in the short -wave field as I have been. Perhaps some of LEARN AT HOME iesa,T,RADIO the other boys can help them out. It is very dis- heartening to some I know and I would like to H E S E five component s Get our big new see these boys get a little recognition, for it is one of the most parts of a 1929 Radio Catalog- interesting fields of the radio and T complete Radio some may give ttp. Fricehhot off the press. Con- instruction Course are outlined thousands of amazing Thanking you for this opportunity, I am, bargains. Latest, nationally ad- J. \V. MANNING, in five volumes that contain not vertised Radio equipment. Latest in Ham Transmission equipment. Daytona Beach, Florida. merely the essentials as so e Everything at lowest wholesale prices. (There are differences between short-wave opera- many books do, but more, they tion and broadcast methods, and RADIO NEWS will NEW RADIO CLUB -Big Prizes deal with them in a series of articles. It mutt contain all that any modern up- Get all the facts about "Ether Trappers' be remembered that the distant short-wave stations to- the -minute textbook on any Club, now. No dues. Many advantages. have generally very small power, and that the Write fomher-r energy subject would cover. They are FREE Me received is very feeble in comparison with ship at once. FREE that in comparison from American broadcast sta- in themselves a COMPLETE This Big Book of money- tions. This necessitates great sensitivity in the radio education teaching every caving bargains is yours short -suave receivers, whose res,nance point is very FREE. A regular Radio narrow; and it is therefore very easy to pass over possible portion of Radio encyclopedia. Write today a short -wave phone station many times if the ex- science. for your copy of this book. act adjustment is not tried. Slow, patient tuning AMERICAN RADIO & MERC. CO. is needful. It will be noted that there is nothing Size of each book 6 by 9 inches, Dept. 10 American Radio Building wrong with Mr. 3fanning's receiver. -EDITOR.) handsomely bound and illus- KANSAS CITY, MO. trated with charts, diagrams, BYRD EXPEDITION CALLS descriptions of equipment, etc. Commander Byrd's ship, the City of New York, Each volume 52 pages. which sailed a few days ago for the Antarctic, has SEND NO MONEY for these this famous been assigned the call \VFBT, while its auxiliary portable transmitter is WFA. Smaller portables are books. Just forward your name cabinet/ KFK, The 7rcyune 50 watts, WFD, 50 watts, and \VFE, 7% and address. We send you the Sizes range from 7x18x10 to 7x30x 12. Mahogany finish, 55.50 to watts. The airplane Fairchild has the call WFS 5s.75. Solid Walnut, 56.50 to 510.25. F.O.B. Hickory. and the Floyd Bennett WFB. books at once. On receipt of Twelve -hour service. Write for catalog. SOUTHERN TOY COMPANY, MANF'R. HICKORY,N.C. In addition to the ship frequencies between 600 same you pay the postman and 800 meters, the Byrd expedition may use these $1.97 plus a few cents short waves: 91.2, 68.1, 53.57 (commercial), 53.10, postage 45.59, 34.05, 26.78 (comm.), 26.55, 22.75, 17.945, and then they are yours. \NEWS to Set Builders 17.857 (comm.) and 13.758 meters. Distributed by Barawik offers set builders bigger bargains - bigger opportunities to make money this season. New seta, new kit OFFICIAL CORRECTION ideas, all the leading parts, dynamic The Consrad Co. speakers, supplies, etc. Lowest rock- The Department of Commerce announces two bottom prices. Bigger corrections of the published list of new inter- Inccrporated . Da.a k af e- national call letter prefixes: CA is Chile and 230 Fifth Ave., New York, N. Y. BARAW 16( CO., CNCAGGáU. HR Honduras. Canadian amateurs will not use , CF for the present, but only VE. Please sal' you sato it in RADIO NETT'S www.americanradiohistory.com Radio News for November, 1928 497 "JUNK -BOX" SET BUILDERS Editor, RADIO NEWS: 1 am using 199s in the "Junk-Box," and I find e them a poor type for short waves. Larger ticklers are required, "B" voltages are more critical, and what -not. However, I am not kicking; the set itself is great. 1í1)R:\ and \VGV cone in around noon without an aerial. I have also logged WLW, K \VKII and 'WEIR:, Chicago; the latter two appar- ently harmonics. I would be grateful for any information on this. I am using 45 volts on the detector and 67% on the amplifier; a 5- megohm grid leak works best. I find also that a .00025 -mf. fixed condenser across the filament terminals of the coil socket helps with MnM some of the coils. Body capacity is bad, but I have on the condensers small shields which lessen it somewhat. THIS shows a medium power crystal controlled BERT VOGEL, transmitter using UX2I0 crystal controlled tube feeding a UV203-A power amplifier. Filament 1541 White Street, Dubuque, Iowa. and plate voltages are to be obtained from Item 34, ope ting (rom either DC or AC house mains. The v Inge to the lamen, of the tubes is variable, either by the field recitan in the filament generator I have made a few changes in the "Junk -Box" circuit [not shown] or by the resistance in the filament circuit of the UX210 is done the bias circuit the 203 -A power ampli er. As set which might be of interest to others who are tube. Keying in of the amplifier is NOT neutralized, the power amplifier must work on some building this circuit. I made a plug -in adapter harmonic of the crystal tube [preferably the second], for all operations in the for my present three -circuit tuner, in order to use 20, 40 or 80 meter bands. A crystal having a fundamental of 160 met n will my two -stage amplifier without rewiring. I found allow operation in all bands with best output in the 80 meter one An 80 meter crystal is best for 40 meter operation and in like manner the 40 meter that, in doing this, I used the tickler coil of my crystal would be best for 20 meter operation. Forty meter crystals arc hard to three -circuit tuner as a radio -frequency choke, and get and blow up easily, so for 20 meten the 80 meter crystal is used again Both tubes obtain plate supply from the plate end of Item 34. the UX210 being sup. it works O.K. - I also picked up an old neutraliz- plied with not over 350 volts through resistente R. and the 203 -A taking the ing condenser and put it in the aerial circuit. I full 1000 volts didn't happen to have the .000032 condensers, so I used .000025s and they Work O.K. with the coil ELECTRIC SPECIALTY COMPANY specifications. It works better than I ever had hopes for. TRADE MARK WARREN B. BARNES, 211 South Street "ESCO" Stamford, Conn., U.S.A, 1532 Lincoln St., Hillsboro, Oregon. Manufacturers of Motors, Generators, Motor Generatérs, Dynatnotors and Rotary Converters for Radio and other purposes I am a "kid" fourteen years old, and a con- structor of the "Junk- Box." When I first con- structed it, I found that my leads were too long and the set would start to oscillate with a groan. I rebuilt it, and as the howling at the beginning of oscillation was still present, 1 put a .002 -mf. fixed condenser across the "A +" and the "B+ Amp." Finding that the condition was not entirely- reme- died, I took the wire off the ticklers, turn by turn, anti found that the following specifications are best for my set: ticklers, 6, 7, 9 and 16 turns, respec- tively, for coils 1, 2, 3 and 4. To date I have received WGV end KDKA on the speaker, and 2X.\L, 2XE and WLW on the phones; I have received code stations as far as the Pacific coast. Being a DX hound, however, I am greatly in- terested in transatlantic reception. I would like to communicate with makers of this set who have had the thrills of transoceanic reception and ]earn of some details of their sets, such as shielding, antenna construction, etc.; and also with construc- tors interested in the Browning -Drake receiver and boosters for it. I will try to answer as many DEALERS AND SETBUILDERS letters as I can. CHESTER TUCHOLSxI, THE NEW 1929 Catalog is crammed 1012 Bremen St., Milwaukee, Wis. full of the FINEST, NEWEST, na- tionally -known A.C. sets, consoles, cabin- ets, dynamic speakers, kits, eliminators, CORRESPONDENTS WANTED and accessories at LOWEST PRICES. Editor, 'RADIO NEWS: Largest stock of Radio Parts. Prompt Our radio club desires correspondence with boys delivery. Write for our FREE between the ages of 13 and 19 who are interested catalog. in DX work on both short and broadcast waves. WESTERN RADIO MFG. CO. We will answer every letter. t2S WEST LAKE ST.I,Dept. RN -11 CHICAGO, ILL. LELAND J. GILLETTE, President, Midwest Amateur Radio League, 7263 Coles Ave., Chicago, Ill. I would be grateful if I could correspond with some young short -wave ham in Switzerland; or some man of experience who would take interest in a boy. A REAL SPECIAL WAYNE. D. DUNN, OFFER! 1044 F .4ve., Nevada, Iowa. UNI- RECTRON POWER AMPLIFIER I would like to communicate with anyone who Ideal for use with Dynamic Speakers) is interested in short waves. WILLIAM BUDINGTON, Model AP -935 95$ State St., Springfield, Mass. As the Uni -Rectron stands The UX -210 super power it is a super power ampli- amplifying tube and the fier, which can be used in UX -216B or 281 rectifying connection with any radio tube are used with this am- The following will be of interest to all short- set and loud speaker. Bind- plifier, which cannot over- wave listeners. The transmitter of Mel- ing posts are provided for load. From the faintest 3LO, input bourne, Australia, is using 5,000 watts on 32 to the Uni- Rectron whisper to the loudest crash and output to the speaker. sound A. Uni - meters every Sunday from 1530 to 2030 G.M.T. of =R. C. Rectron amplifies each note (1:30 to 3:30 p. m., E.S.T.). ANIL, Mt. Mala- Requires no batteries for its its at its true value. High and bar, Java, 17 meters. has 40 kw. power. 9 amperes operation. It obtains low treated 110 volt, List Price $88.50 notes are all in antenna. : \NE, Bandoeng, Java. 15.93 meters, power from. the (without alike. The volume 60 cycle alternating tubes) deliv- has 7 kw.; S amperes in antenna. Announcements current lighting tir_ and quantity of these stations arc made in Dutch, ered will be a revela- English, cuit of your house. Special ,19.75 ea. tion. French and German. Every one new and packed in original factory carton I world like to correspond with short -wave en- thusiasts in foreign countries. AMERICAN SALES CO., 19 -21 WARREN ST., NEW YORK CITY WRAY GILLETTE, SEND FOR OUR LIST OF RADIO BARGAINS 923 IP. Anderson Are., Ft. lIycrs, Fla. Please s a 4 v o lt san' it in RADIO NEWS www.americanradiohistory.com ` Ç Radio News for November, 1928 The Radio Constructor .`... Build a (Continued from page 459) Daven Television BETTER USE PHONES % Editor, RADIO NEWS: \ it;ll,' / ' Receiver I made the Loveless antenna exactly as directed, Cn1111,1ete Essential Kit, $60.00 connected the coils as per diagram, and all I re- ceived was dead silence. I reversed the \ connec- `` f THE first complete Kit. Furnished tions to see what would happen, and again received with either T-24, T -36 or T -49 Scanning Disk, Motor, Bushing, nothing, Rheostat, Daven Television Tube. 3 I threw off the ground connection of coil, and Complete Stages of Daven Television immediately received very weak locals. Catch- Amplification and Instructions for ing hold of the ground and of the aerial, I found Building. a great increase in the strength of signals if I Daven Television Receiver, Complete, squeezed the end; signals weakened if I merely including Television Tube- $too.00 touched the end. I tried this with an old two - Less amplifier Tubes.) tube Crosley connected to a three -tube Sonatron -in all ils phases amplifier. I received WOR, WENR and KFI, TELEVISION DAVEN stations I never had before. Complete instruction APPARATUS I took the antenna upstairs and connected it to a course in three three -tube Bremer -Tully hook -up, and the result volumes. Every point of aviation effic- Daven Television Scanning Disks was again dead silence. Back to the basement, and iently and thoroughly treated. Subjects z4 T- the stations mentioned covered in 36 T -36;6 were again heard with the these volumes- 7.50 Crosley. 48 T-48 10.00 Comb. Disc with 24, 36 and 48 Aperatures T- 468... 15.00 I then tried the Loveless antenna in connection Damn Tele. Amp. T -3 11.50 with a Freshman lamp- socket aerial at the "ground" MODERN Daven Spec. Telev. Amp. T -4 for t Hi Mu Tubes and end, and succeeded in rousing the whole house with z power Tubes 171, rio, z5o Types 17.50 \ \-h:NR's new AIR CRAFT Daven Telev. Neon Lamp, zo to So transmission. Milliamperes That ended the Stricking Voltage too Plate 1 jdj'n n.5o experiments, for wrathful noises Daven Telev. Motor began to emanate from the upper regions; my wife, Daven Bushing to fit 700 Pages X', 54 and W. Motor Shafts 1100. who calls herself a radio widow, began a series of Daven for 48 Aperture disc interferences with home -made static which sounded 500 Daven Rheostat Illustrations 3.50 like: "Fancy having that going at 2:30 in the morn- Daven Telev. Photo Elect. Cell 1' Bulb z0.00 Daven Telev. Photo ing like a locomotive!" Elect. Cell 3' Bulb 37.50 Daven Television Couplers. JAMES HATTON, Contents of each chapter - at Stage No. 4ux D -4zrax 107 Ennerdale I. Aircraft Types. H. Road, Fairbank, Toronto, Can. Lighter -than -Air Ind Stage No. Ozu Doux (Even discoverers must have some consideration Craft. ;rd Stage No. 4235 D t;az III. Early Airplane De- for the neighbors. The latter occasionally need Glastors are used for Grid and Plate resistors 1.15 signs. General Design Davohms sleep. As to the Loveless antenna, variations in Considerations. W. De- 1x Super in Plate and Glastors in Grid 4.6$ Daven AC 71 for output tubes in series with Tele- the resistance of the ground connection, as well as sign and Construction of vision Lamp in the inductance and capacity of the device, are Aerofoils. V. Arrange- 3.50 ment, Fabrication and Bracing of Airplane Wings. Daven AC to (for brighter illumination).. 9.00 apt to produce very different results for different `'I. Daven Mu to Hi Tubes Airplane Fuselage and Lan ding Gear Construction, Mu for Amp. Stages 2.15 experimenters. However, like Mr. Hatton, they Daven Mu 6 Power Tube VII. Airplane Power Plant Types and Installation. 3.50 may get lots of faun trying. We suggest a test VIII. Aviation Engine Design and Construction. Send it stamp for new Television Booklet with a variable condenser across the two open ends Air-Cooled Engines. IX. Aviation Engine Design of the windings.) and Construction. Water -Cooled Engines. X. Avia- THE DAVEN CORPORATION tion Engine Auxiliaries. XI. Aircraft Propeller Amplification Specialists Construction and Action. XII. Airplane Equilib- 163 'Summit Street Newark, N. J. rium and Control Principles. XIII. Uncrating, Set- ting Up and Aligning Airplane. XIV. Inspection and I\NQ UIRIES for information not given Maintenance of Airplanes and Engines. XV. De- here should be sent to the constructor tails of Modern Airships and Airplanes. XVI. Sea- direct; but he should NOT be asked to planes, Flying Boats, Amphibians and Other Air- furnish data already published, here or craft. XVII. Some Aspects of Commercial Aviation. elsewhere, or for XVIII. Aircraft Instruments and Aerial Navigation, instructions that an ex- XIX. Standard Nomenclature for Aeronautics perienced builder should not need. Report No. 240, Part I. This department is for free discussion to This book is written in simple, understandable the extent that space permits; but RADIO language. NEws accepts no responsibility for the PRICE $5.00 opinions of readers as to the relative merits of apparatus and circuits. AVIATION THE BARAWIK CO. has, all these years, ENGINES been famous for its variety of radio supplies. which it offers at money- saving prices. New- This treatise, written by a est dynamic speakers,' /3" eliminators, socket A HALF -GALLON ANTENNA recognized authority on all of the practical newts of power equipment, A-C harness. fine cabinets Editor, RADIO NEWS: internal combustion engine and furniture, amplifiers, latest amateur The article on Mr. Loveless' aerial caught my construction, maintenance, equipment, tubes, batteries; in fact, anything eye, and I had to have and repair, fills the need you can ask for is here, ready to ship, at a one like it. Instead of as no other book does. saving in price. Quality merchandise, selected getting a large tube, I used two -quart Sealright The matter Is logically goods by reliable makers you containers and some No. 26 D.S.C. wire. I wound arranged: all descriptive mat- - just what ter Is simply expressed and want - at big discounts. 225 feet of wire on each of the tubes, both of copiously Illustrated. so that which are 7 inches high. The outer is 354 inches anyone can understand air- Your Savings areTremendous in diameter; plane engine operation and the inner was slit and lapped to re- repair even If without pre- Ask any of the quarter million Barawik customers duce it to 3 inches. slow mechanical why they trade training. here, and they'll tell you that, I have a six -tube T.R.F. This work Is Invaluable .or quality considered, our prices can't be beat. set and a five -tube anyone desiring to become That's something to think about! Quality comes Freed - Eiseman and have had fine results on both; an aviator or aviator mechan- first -new, fresh, good reliable merchan- but lately radio reception ician. dise, but the price always means a here has been rotten and tremendous saving, nevertheless. static awful. With the aerial as described on the 274 PAGES PRICE Get our catalog and prove this T.R.P. I logged \VEAF, WJZ, WOW, $1.25 to yourself. Don't spend a WRR, nickel until you see our offer- KTHS, several Chicago and Cincinnati stations, ings first. Mexico City and Havana. The last two are almost A. B. C. OF You need this great radio impossible on an outside aerial in the summer AVIATION bargain book as never be- here. When I connected the coils to my outside fore - Mail the coupon aerial, my volume This book describes the basic now - TODAY. increased fifty per cent. principles of aviation, tells At present I am winding 300 feet of No. 26 how a balloon, or dirigible is D.S.C. made, and why It floats in the BARAWIK C0.111 iAAGö'úss on the pint -size Sealright cartons, and will air. Describes j °a see what they will do. have bow an airplane I a 200 -foot outside flies. It shows In detail the l Mail This Coupon for FREE Bara.ln Book. aerial. It is 45 feet up at the lead -in, runs north different parts of an airplane. and south 100 feet and then west to an oak tree, what they are. and what they Name do. Describes all types of air- where it is about 90 feet high. In the winter I planes and how they dicer in get wonderful results. I have also a sub aerial construction, as well as de- tailing the advantages and which I use during storms. disadvantages of different __J I am anxious to see what can be done with short- typen of aircraft. It Includes a wave complete dictionary of avia- reception on these coils, but will have to wait tion terms and clear drawings until my set is built. I.intend to experiment fur- of leading airplanes. ther with the coil antenna. MAGIC J. M. FRANCIS, PRICE $1.25 Taught at Home! 1507 Thirteenth St., Tuscaloosa, Alabama. New! Differenti Teaches you Big Tricks, Illu- sions, Stage Stunts. Pauer and the Prin- (Simultaneously with the above, there arrived Remit by cash, stamps, check, or money order of Marie. Learn at home. Earn 1260 to S1'pÌes.000 a month. Write today for b fw. letters from other readers who had no success, and No C.O.D.'s SYSTEM, were inclined to be skeptical about the whole mat- Mme` SunnyR1 lde Av . 10.08 Cfleago, Illinois ter. The uncertainty about any radio circuit is, We Pay Postage On All Books at least 90 %, in its aerial and ground circuit; Insure your copy reaching you each month. Sub- there is no universal prescription applicable every- scribe to RADIO NEWS -$2.50 a year. Experi- where. One man will get excellent results with a CONSRAD COMPANY, Inc. menter Publishing Co., 230 Fifth Ave., N.Y. C. certain peculiar antenna; another none. In one 302 FIFTH AVENUE NEW YORK Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 499 place a listener with two tubas will get .4 nstralia and England; in another it cannot to done with the best ten -nrbc hook-up. These are matters still in the realm of experiment.- Eoiroc.) A few cents a day A SMALL TUBE GETS RESULTS Editor. RADIO Nrws: brings you I trier! out a small edition of Mr. Loveless' aerial. I simply wound a hard- rubber tube 3 inches in diameter and 7 inches long full of loop - 1_16 aerial wire, and another tube a little smaller full T1-1 OlJ S.AN DS of the same, and put it on my 5 -tube set for an experiment. It brought in local stations 100% better, with SPEAK ° R.., slight loss of volume and a change of about 7 CIF points lower on the left -hand dial. When I tuned for DX, I brought in WSM, which I couldn't get OPER4TION on my regular aerial, but threw the left dial so DOLL/MA far off (about 13 points above 45 on the dial, and from 7 to 10 points below this) that I didn't like . by RCA, G -E froren it. So I just hooked both leads to the ".\er" post Sponsored a found work much better on and it to all stations than my outside aerial. With this connection I and Westinghouse, this brought in approximately twenty -five stations on August 11th, including some I couldn't get any radio course qualifies --CRYSTAt other way. Then I put it on the short -wave "Junk -Box" receiver and it worked better; so I you for big earnings BAT- left it on. I couldn't get anything without the NO "TUBES""TUBES"-NO "B" ground. Do you suppose an "A and B" power TERIES - NO COSTLY unit would cause such a change in the settings.since and SUCCESS. the eliminator is grounded ? My groceryman is "ELIMINATORS" making a regulation Loveless aerial, so I'll try IDE -AWAKE men -here is your golden WITH THE it out. I am pleased with the "Junk -Box," and if I opportunity. A few cents a day, real SKINDERVIKEN had used best -grade parts, perhaps I would get for- ambition to succeed, and you can increase eign stations also: but being next to an ice-cream your earning power by hundreds of dollars factory probably affects DX. I get 2XE and WLW TRANSMITTER UNIT regularly; but KDKA does not come in as regu- each year -many thousands during your Simple microphone unit provides a most effec- larly as I thought when I built the set, and I active business career. tive and inexpensive way to satisfactory speaker have not had 2XAF; though I have tried hard operation. Easy to build and operate circuit. Everybody can do this now with for it. The Radio Institute of America, conducted a Skinderviken Transmitter Unit. E. C. HAVES, by RCA and sponsored by General Electric The unit is fastened to the dia- 324 Plymouth .4re., Buffalo, N. Y. and Westinghouse, offers you at low cost phragm of the speaker unit. It will (Adding inductance to a tuned aerial coupler net as a "micropfonic relay." Every must, of course, alter dial settings, unless capacity the training you need for success in radio. time an incoming signal actuates the diaphragm, the electrical resist- is also rednced to make up for it. .4s for the power up- ance of the microphone unit will be unit, its effect would depend upon the actual re- Nothing so clear, comprehensive and varied correspondingly and the cur- sistance-to ground -of the system.) to-date, nothing so generous in apparatus rent from the battery. in series has ever before been offered in with it and the loud speaker, will fluctuate accordingly. furnished Thus the problem of securing sufficient power WE SUGGEST ASBESTOS PHONES radio training by any organization. to actuate the loud speaker is simply and adequately sol ved. Editor, RADIO NEws: This is basically the same course that has and unit The results from this very novel simple I write this listening to a concert from KFAD, you. enabled our thousands of graduates to ad- will astound Phoenix, with loud -speaker volume, while The expense of this hook -up is trifling compared good vance to positions of importance and high to the elaborate tube circuits that give no greater the temperature is around 102 in the shade (Sorry act =Non of the speaker. O11). My longest reception is WGY at 4:30 p. ni. remuneration in the respected profession Besides this there are many other valuable uses in in the winter. As for night reception, all winter of radio. But new and revolutionary IGulio Circuits for this marvelous little unit. Every long I crawl out of the hay to pick up real DX. builder have a few on hand. make the instruction clearer and of Radio sets should Here are verified receptions: JOAK, JOBK, changes LISTENING THROUGH WALLS Japan; JOD1c, Korea; 2BL, 2FC, 3L0, 4QG, easier, permitting faster progress -and the This Unit makes a highly sensitive detectaphone, 5CL, Australia. (Not verified, JOBK, Japan; course now embraces television, airplane listen walls with ease. the real thing -you through 2YA, New Zealand.) All this on three tubes. radio equipment and photoradiograms. ' Plenty of fun and real detective work too. From October to February, there was hardly a CONDUCTING' SOUND THROUGH night I did not get JOAK and 2BL with good Furthermore you can study at home-when WATER phone volume and loud- speaker volume that could you please and as long as you please. Your he heard twenty feet away. Make yourself a miniature submarine signaling rate of progress is limited only by your apparatus like those used during the war. Simple I would like to get in touch with DX fans circuit with this microphone unit gives splendid results. who are using small sets and getting real DX, own ability. as I want to compare notes. 12-PAGE INSTRUCTION BOOKLET I like RADIO News much better since the change Here is a coupon that is well worth mailing. It containing suggestions and diagrams for innumerable in brings you-free -an interesting illustrated book- uses, furnisher) with each unit. policy. GILBERT HALE, let that shows the tremendous opportunities in the Douglas, Arizona. radio industry and outlines the Radio Institute of P. G. MICROPHONE TRANSFORMER America's course of home study. A Modulation 'Trans- If you are really looking for a future -if you are former specially de- PHONOGRAPH SWITCHOVER really out for Success -mail the coupon now. signed for use with the $kinderviken Trans- Editor, RADIO NEWS: mitter Unit. Has many I recently invested in a phonograph pick -up; one other uses. Primary of those which, by inserting a plug in the detector RADIO INSTITUTE resistance, socket of the set, allows you to use the audio OF AMERICA )iohm;see- tnd as an amplifier for the phonograph music. ondary, 55 Dept. A-11 326 Broadway ohms. New York, N.Y. FOR SALE AT LEADING DEALERS SECONDARY PET. TUBE -G Or Order Direct, Using Coupon Below I :. AUDIO RADIO INSTITUTE SEND NO MONEY TRANS. When the postman delivers your order you pay him for -F OF AMERICA whatever you have ordered, plus a few cents postage. NOT US.D 1 Dept. A -11 326 Broadway PRESS GUILD INC. R.N.-11-28 A- New York City 14 -18 -R -East 30th St., Ness York, N. Y. ANY- WHERE Please send me your new booklet with Please mall me at once as many of the following items VOLUME CONTROL as I have Indicated. IN SET. full information about your Home JACK :. ( PICK-UP ..Sklndervlken Transmitter Units at 95c. for 1; 51.75 Study Course of Radio Instruction. for 2: $2.50 for I: 83.20 for 4. .. P. G. Microphone Transformers at $9. When delivered I will pay the postman the cost of the Items specified plus postage. Name PHONE PLUG Name EXTENSION CORD Address TO PICK -UP. t Address.. . City City State Sir. Miller's switching arrangement. Please say you saw it in RADIO NEWS www.americanradiohistory.com 500 Radio .\'ewers for November, 1928 1 Make Sure That My Entire Family Reads "YOUR BODY " - -- There's a Reason "INVARIABLY, every time I bring home BODY. They know that it is a medium devoted 1 the new issue of YOUR BODY, my to the welfare of the human body and that it is daughter makes a rush to capture it. I to their advantage to read carefully every page. don't Sex, psychology, treatment of all maladies, the stand a chance of getting it back until she senses, our instincts, all are fully explained in the has digested its entire contents. Of course plainest of untechnical language. In YOUR I have to be reasonable. I realize that, much BODY there is a section for every member of the as I want to read it, the contents of YOUR family, mother, father, brother and sister. Go to BODY is of great value in teaching her the the newsstand today and get your copy of this valuable magazine. Over 112 pages -fully illus- real truths of life. I know that each issue trated -large magazine size. is practically an endless source of informa- tion on sex, prevention and care of diseases, the senses and the normal functions of na- CONTENTS ture as related to our bodies. All of this FALL ISSUE worth -while knowledge is of great impor- Decoding the Sex Question tance in forming a basicly firm character in Evolution of Our Footgear adolescent children. That is the reason I Hermaphrodism willingly share my newspaper with my wife Why the Doctor Examines You from Head and wait patiently until Madeline, having to Foot read every page, grudgingly hands it back. Wonders of Biology Menopause or Change of Life However, in the future, I have a little The Art of Living scheme that will make it possible for both Sex Education of us to read YOUR BODY at the same Chemistry of Our Digestion time. I am going to buy two copies; then Twilight Sleep I won't have to wait." The Art of Healing at the Dawn of History Before the Baby Comes Whooping Cough This is the story that just one of our readers Psychoanalysis tells. We know that there are many more homes Etc., etc. throughout the country where the same condi- tion prevails. Our readers have found a world 50c. per copy of valuable knowledge in each page of YOUR AT ALL NEWSSTANDS OR WRITE DIRECT EXPERIMENTER PUBLISHING COMPANY, INC. : 230 FIFTH AVENUE, NEW YORK, Y. Please say Ton sa,;, it in RADIO FEINS www.americanradiohistory.com Radio News for November, 1928 My set having only the ordinary two -stage am- plifier using 201 -A tubes, did not give me enough volume. After a little figuring and experimenting I came across a way in which the detector tube could be used along with the audio tubes, making in all a LYNCH three -stage amplifier: and that without having to remove the detector tube every time you want to TELEVISION rue- your pick -ul.. The result is all the volume you need. The only apparatus you need for changing over Amplifier Kit your set is a double- circuit jack. (which you prob- ably have lying around among some old junk), two phone tips, a phone plug and also a few pieces of rubber-covered wire for connections, Remove the two connections that are soldered to the positive filament and plate prongs in the socket plug and attach phone tips to each, so that the terminals can then he placed in phone plug, which in turn can be placed in the jack whenever the nick -up is to be used. The diagram explains the way in which I con- nected the jack in the circuit. By studying the latter closely you will see the way it functions. J. Co MILLER, 310 Riclle Avenue, Verdun, Que., Canada. A PROUD CONSTRUCTOR this precision -built kit you can assemble Editor, RADIO NEWS: WITHat minimum trouble and expense an efficient I received my copy of the September issue and amplifier for securing quality reproduction in was surprised to see the Strobodyne dressed up in your television reception apparatus. a new suit of clothes. I am the proud possessor an Strobodyne. which constructed last The audio amplifier is an extremely important of original I part of television receivers. Where the signal to fall, and with it I have received coast -to -coast be received contains frequencies of from 18 to under favorable weather conditions with tremendous 20,000 cycles, the audio amplifier must be able to volume. I deviated a little from the original amplify all frequencies within these limits. Such design by incorporating one stage of resistance an amplifier is available at your dealer in the and push -pull Lynch resistance coupled amplifier kit. coupling in the first stage audio in the last. I have tried out many circuits, but Your dealer has a Lynch precision - none SO far has surpassed the Strobodyne in per- built resistor for every resis- tance need. Send for free book. formance. I am anxious, therefore, to try out the new circuit to see if it is actually better. Please send blueprint No. 63, for which accept ARTHUR H. LYNCH, INC. my thanks in advance. General Motors Building JOHN C. A. COtSOER, 1775 Broadway, at 57th Street 1076 So. Lee Street, Des Plaines, Illinois. New York, N. Y. UNSUITED TO OTHER WAVES Editor, RADIO NEWS: I thank you for your reply to my letter, though you misunderstood the query. I have now as fine a Strobodyne as anyone could wish, using S -M plugin coils rewound to suit. I have no trouble in getting J DKA and CKGW on 'twelve inches of antenna, right now in this hot weather; but what Put your set and loudspeaker I wish to get information on is this: anywhere. Place them as far What may I expect from 18 to 200 meters and con- from 550 to 3000 meters with coils to cover these apart as you wish. Then bands? I have started a screen -grid Strobodyne. nect them with the wonder- Will you please send blueprints Nos. 62 and 63 ful Belden Extension Floor íHI I)ëII.o and oblige. ®T T. RASMUSSEN, Cord. It lies flat under the 649 Spaulding Ave., Chicago, Illinois. rug. Out of the way -no II4AFAYETTIE (The American Strobodyne is not designed with wiring fuss. Get one at, a view to obtaining such a [ride range, and while -no toils might be obtained to cover the European your dealer, now! ATLANTIC CITY. N. al broadcast bands, it is not recommended with so delicately -balanced a receiver. .9s for the short- A new and beautifully furnished wave broadcasts, the simplest remedy is to use a Fire -proof hotel situated on South one- or two -tube short -Le'av'e tuning unit, such as Belden North Carolina Ave.. in the Board- have been described in recent issues of RADIO NEWS, Mfg. and plug into or connect by switch to the ' walk block near the Steel Pier. receiver's Company audio amplifier. This involves fewer complica- Where personal service,homelike 2114-A tions that the attempt to use the intermediate surroundings and superior foqd S. Western amplifier of the superheterodyne.- EnreoR.) abound. Avenue Carefully selected clientele and Chicago friendly prices. Write for Book -; REFORMING A TIN HORN let D. _ Editor, RADIO NEws: Arthur 0. Franklin. Everett L. Cope, Proprietors I believe I can go Mr. Coleman several better in regards to treating a "tinny" horn. One of my first really good speakers (three years ago) was an old- fashioned "flower" horn and tone arm from a Victrola. I removed the entire horn and bracket from the cabinet and mounted it on the edge of an oak block 6 x 6 x 2 inches, which made a very good base. I then melted two cakes of paraffin, into which I dumped about two tablespoonfuls of salt and one -third of a cup of vinegar; and painted many coats of this preparation, while very hot, on Every farm, evert home, every man and woman needs radio this year to follow elections. markets. the inside of the horn proper. After allowing it !big national events, football. sports, music, etc. to dry for several days, I painted this with bronze Barawik's Big Radio Guide tells you the best sets. snethods and supplies to use and bow to use them paints of different colors, to represent a large tor best results at lowest cost. Thousands of clear morning glory. Use your own taste for colors and illustrations and latest valuable Information, fur- design. This horn, after being so treated, is the nished free. Just send for Barawik's Big Radio Guido, the guide to radio and real radio enjoy- equal, if not superior to, an all -wood horn. This ment. You can get what you want here at mixture is very hard when dry and will stand hlggt $t savings. \\'rite today for free copy. Sta., very high temperatures without melting or be- BARAWIK CO. HICAGO, A. coming greasy. Man this Coupon for Free Radio Guide. :My latest speaker is a coiled up 12 -foot exponen- tial horn with a Baldwin concert which makes Name unit, a very pleasing home speaker if coupled to a good Address A.F. amplifier. I am using a 5 -tube set with one screen -grid R.F. stage, regenerative detector Plcasc say you safe it. in RADIO NEWS www.americanradiohistory.com 502 Radio News for November, 1928 (1I2A), one stage of straight transformer A.F. (112A), and a last stage of push -pull with two ran. smission of Photo's by Radio 171A tubes and 180 volts on plate. Will some of the fans send in data on their ANSMISSION OF PHOTOGRAPHS thè electron flòw constitutes a dis- experiences with airplane cloth speakers? I am BY RADIO - Various methods have charged circuit, so that the grid be- just getting material to build my first. been devised and are now in use for comes less negative. The first ampli- M. A. PORTER, the transmission of photographs by fying tube is a direct current potential 1616 Mohawk St., Chicago, Ill. radio. Among these may be mentioned amplifier, and is resistance cô :pled. the systems of Belin (q.v.), Baird, and The grid and plate connections of the FILAMENT INPUT Jenkins. The principles underlying amplifier are connected across a con- Edtor, RADIO NEws: the Jenkins system are explained denser which becomes discharged with I note some records reported by set builders under the heading of Television. the fall in the grid to plate resistance claiming to use new hook -ups with 15inch to 15- Using the system developed by Capt. of the valve brought about by the grid foot aerials. If they will take the ground wire R. H. Ranger, photographs were potential fluctuations. A charging cir- off, they won't get these results; might just as transmitted by radio from Honolulu cuit' is connected to the condenser and well use no aerial at all. If either "A -" or to New York, a distance of 5,136 miles. is controlled by a valve, the grid cir- "A +" or "B -" or " +" is grounded, on turning the filament up a signal will enter the receiver via Recently commercial picture trans- cuit of which operates by variations ground through mission service has been inaugurated of the potential across the condenser. the filament of the R.F. tubes, to between the plate. I have cut out all grids of R.F. tubes, New York and London using The charging current is fed through put ground on "A -" and received stations to either the Ranger apparatus. Two distinct the plate circuit of this valve, in which coast, using only a straight settoground wire. I ethods have been applied for analyz- a relay is connected, which working also find this can be done using a power unit; a ing the picture in the process of trans- through other mechanical relays in signal comes in via the "A" unit, filament to plate, etc. If you want a real test on these remarkable re- ceiving sets, disconnect both aerial and ground; use the old -fashioned "A" and "B" batteries: then see how much aerial it requires to get enough power for loud- speaker volume. O. R. AIKMAN, Salem, Illinois. (Some of ]1r. aikman's fellow-experimenters who haven't been able to get the coast on a 150 -foot aerial will probably Leant to know Irmo he does it. How many readers have been able to receive on tlic power-unit line alone as an aerial.'-EDITOR.) A DOUBLE -GROUND SYSTEM IN EUROPE Editor, RADIO NEws: I read with interest the article by Dr. W. Grif- fith, as I have been using his hook -up for the last fourteen months. I inherited a V- shaped aerial, aboui 120 feet long and 40 feet high and, as it gave excellent results, I had no reason to inspect it any closer. One day I noticed by chance that the other end A pencil of light traverses the picture which is attached to the glass drums and is analyzed by a was carefully grounded. First I wondered slow rotating action as well as a backwards and forwards movement of the carrier. how my set could have worked at all, but soon I realized that I was using a big loop. My set is a power Supradyne, which is wired mission. One arrangement cbhsists of cascades, controls the radio trans- for operation with loop and aperiodic aerial. It roducing an image as a non- conduct- mitter. , Wave trains from the trans- reaches easily the noise level. As soon as the deposit upon a metal foil which is mitting, station after detection and idea of the loop had struck me, I changed the versed by a stylus, while the other amplification, are applied to the pic -tt connections over to the loop terminals, tuned it as thod makes use of an opaque image ture recorder. The recording mechan- such, and found that the set worked about equally osited upon a transparent film ism, in order that it may be sensitive well. iich is traversed by a beam of light, to exceedingly small currents, com- This aerial gives good results with wavelengths le light interruptions being recorded prises, a small moving coil, in a mag- from 15 to 3,000 meters. At night, a 3 -tube, short- y a light sensitive cell. The Ranger netic,fleld created by three electromag- wave set fills the house with good music from rstem 2XAD right across the Atlantic Ocean. makes use of this latter method. nets. The coil of wire, in moving in I wish to call the attention to another very he image is p r to.. - rded the field, as the received fluctuations important fact. For wavelengths of the American ipon a cel broadcast band, the noise level can be lowered ecor considerably by connecting the ground wire only to one of the terminals marked "loop." It has to be tried out, which one of the two gives more vol- ume. The volume decreases but, if the set is pow- S.Gernsback's erful enough to be brought up to the same volume, it will be found that the noise level has been lowered considerably, and that stations can be Radio reached which were well below the noise level before. If the lead -in wire is eliminated, or if the loop Encyclopedia is closed, all reception is cut out. This shows that, even with the ground -connection alone, the whole A facsimile of a portion of a page from S. loop is at work and not only the ground part, as Gernsback's Radio Encyclopedia is reproduced might be supposed. herewith. A glance at the thorough manner in For long and very short waves, always have which each item is treated cannot fail to instill a I true appreciation of the value of the remarkable to connect both wires. The directional effect must book. S. Gernsback's Radio Encyclopedia is be very small, as America is coming in at right the first ever published. It is not a dictionary. angles almost. It covers every possible phase of radio. Every OTTO BAUMANN, circuit, each piece of apparatus, the all leading 3 Travessa do Ascite de Oliveira. characters of the industry, broadcasting, re- ceiving, television, telephoto, everything con- Barreiro, Portugal. nected even in the slightest way with the growth of radio or its kindred sciences, is most authen- tically explained. There are over 1930 separate IN' THE WINTER, THEY DON'T FISH definitions, 549 illustrations, a complete cross Editor, RADIO NEws: index, and many other special features. I can term myself a listener, for about three S. Gernsback's Radio Encyclopedia comes in months out of the year- during the dry season; for two beautiful bindings, large 9 x 12 in. size. reception is quite impossible, on broadcast waves, Cut here COUPON Cut here during the wet season. We on the Canal Zone find it pretty nice to "rear back" in our chairs and get the baseball scores almost as fast as they recording mechanism the Beautiful Limp Suede Edition (de luxe) $5.00 of receiver. Thy are made. And it's also nice to be able to drag which a moving co Keratol- Leather Stiff Binding $2.00 in a concert from England or Holland (short. Write your name and address in the margin wave, of course), even though there is a little below, mark which binding you prefer, and applied through its windings, squeal or motor noise "back of it." It's better the book uiU be sent to you C. O. D. plus ates a- stylus while travelling than going to a theater and sitting in front of a postage. ss the surface of the paper. The gum- smacking, title -reading, so- called "listener," us traverses the -paper in perfect who explains aloud all the scenes of the thriller. S. GERNSBACK chrony with the carriage of the We're all anxious to hear new ideas to improve 230 FIFTH AVE. NEW YORK, N. Y. nsmitter, the paper being Iifted broadcast reception, but we don't want the blah of a few high -hat listeners who haven't even an ama- teur op's license. In spite of the powerful "locals" Please say volt saw it in RADIO NEWS www.americanradiohistory.com 503 Radio News for V ovetnber, 1928 (b- r- o -a -d, powerful spark and LC.W.). we Zouìtcs get a good deal of enjoyment out of the little black boxes. TUB Broadcast stations in the States are as thick as I.izzies. It seems to me that it would be better to limit the stations to one to each state; Texas might need two. ln that way, I think, we will -0-0-t--10 RADIO a great deal and lose these '-fox -in -a- hencoop" jJ//Pau mountecl gain programs that have been reported heard in Hague, S. D. C. MAYNE ROY, Hq. Battery, Ft. Sherman, Canal Zone. COAST -ZA - -Ai erj so far as the Canal Zone is t,COAST W (A simple solution, (» concerned, and where all broadcasts are DX. . 1,, 'A. RECEP- !'vm' Will meet conditions in the U. S. .4., TION Whether it high let the Radio Commission bear witness. However, Superphonic 7 is world beater! An exceptionally sta- AMPERITES take little grade receiver that is amaringthe Radio World. Latest the increasing number of short -wave broadcast radio tre ncy circuit, using 4 radio frequency to the dwellers in distant space, but they control tube tuned Power tube can be tions is bringing comfort amplifiers, detector an 2 etagesofaudio. not only of the United States, but of all very life blood of used in last audio stage, Extremely selective marvelous sen- outposts, the sitivity. Single drum dial control. Straight line wave length the countries of Europe.) your receiver by auto- condensers permit accurate, equally spaced tuning over en- tire wave band. All sockets spring cushioned to eliminate matically regulating Bakelite subpanel SWW" deep ) insures -AS THE LADY SAID, WHEN microphonic noises. guar- the tube filaments. minimum dielectric losses. Clear and rmfistic reception COW An exceptionally beautiful. walnut finish, metal front SHE KISSED THE pays to use AMPERITE- anteed. to . All It 7" x 18 ". Complete chassis. No extra parts Editor, RADIO NEWS: panel No special tools needed. All the' only self-adjusting resia. parta mounted ready to wire. see why people spend so much money to hook-up wire and colored battery cable included. Value I can't tance for "A current. Main- $60.00; our price S16.95. buy sets or make them; this also includes speakers. tains filament temperature at TESTED AND APPROVED I know many who have $30 speakers, and still their proper voltage despite varia- tests haveprovedthe remarkable efficiency I I have the cheap- Severe laboratory us lettere prais- results are not so good. think tions in supply. Essential with of this . Owners everywhere est speaker in the world and the most perfect for unlike ing its set r receptive quale eliminators.. Entirely WIRING DIRECTIONS that price. It is a unit with a 10 -cent megaphone fixed resistors. Instantly inter- SIMPLE My sets are a five- - Very easy to wire this set with the instruction we furnish. over it and cost me $2.69. changeable. Banishes hand connect a few wires. All you have to do is to follow tube T. R. F. set and a six -tube resistance -coupled panel lay. Just numbers. Simple as adding 2 and 2. rheostats. Beautifies Can be wired in a few minutes by anyone. set known the world over for its selectivity. Many out. Saves wiring. A type for No radio knowledge needed. Make money of my friends who have expensive sets and speak- every tube -battery or A. C. by wiring these sets in your spare time and have to admit that (in U.S. selling them to your friends. ers, both built -in and separate, 81.10 with mounting my sets sound 100% better than theirs. Both give A.), at all dealers. me very good results both on low waves and high waves, and both cost me less than $25 complete. one poet card and ask us to send rdiall eomparly Just write your name and address pay only I use 135 volts "B" power on them, with a power this wonderful outfit. We ship right away. Uponarr,yal send 50 FRANKLIN 5T., NEW YORK $Ì6.9S plus mall delivery harge. (Foreign countries tube in the last stage, and either a 200 or 201A 519.50 with order. We pay shipping charges.) detector. An output transformer helps to clarify. RADIO EQUIPMENT CO. "Amrerits Blue -L. CHICAGO, ILL. SAMUEL DONNER, Book' S. Welts St., Dept.12 Circuits °riti haw- 549 309 Floyd St., Brooklyn, N. Y. to-build data. Write brut R. N. 11 WHEN A GROUND'S OVERHEAD Editor, RADIO NEWS: Ti AXLE The generally- accepted doctrine that a water Jb tja pipe makes the most perfect ground was abruptly Yrzca- `11íe "SELF-ADiJSTiNG" RheOrtnt shattered, to my mind, when a peculiar constant a1 hum that has been present in my set for the past Rheostat five years instantly ceased on my changing to a Junior deep earth ground. This hum was of variable Small in size, but a intensity, apparently coordinated with electrical master instrument. conditions in the air, and attended long- and Ask your dealer to short-wave code as well as broadcast reception. show you the ex- My diagnosis is that there was a six -foot range ceedingly fine ad- boiler in the water -pipe circuit, and this was in justment and vel- metallic connection with a steel standpipe 165 feet above the set. This in some way brought about a vet smooth action. 'The newest radio wrinkles -A-C, grid tube. conflict or interference between the radio waves. dynamic speakers, Diameter, 1?fG in. short wave, television, In any event, divorcing the combination ended the newest tubes and circuits -anything and Up to 400 ohms $0.75 trouble, and my 150 -foot aerial seemed to appre- everything in radio-are now ready for 1,000 and 2,000 ohms 1.00 relief. With elections, foot- extra .25 ciate the you at Barawik's. Potentiometers C. E. BUZZELL, ball, National broadcasting, Rosy and Self -attaching, positive -acting switches River, Ill. the air, thou- .40 Leaf other big doings filling for Junior Rheostats will take to is possible that a pipe line may contain an sands of newcomers (It Busi- FILAMENT AND GRID TYPE insulating meter, etc. -between set and radio this year as never before. ring- builders will UNITS ground; and an extremely long antenna system ness will be good -Set RESISTANCE You can clean up big subject to power-line pick -up resulted. .lfany of make money. Here is where you need absolute dependability by Buying from Earawik-the old- and you get it with Yaxley Resistance Units. our readers may be able to take a tip from Mr. screw eye est, biggest, most reliable radio Runt true to rating. Convenient Bacaell's experience.- EmToa.) in the world. Let us prove it. and soldering lug terminals for easy mounting. house One to 3,000 ohms, 15c. to 40c. Send now for the Big Book-all WHERE THE DX IS ready for you-free. Get the latest YAXLEY MFG. CO. radio information and lowest prices. Editor, RADIO NEWS: N 9 So. Clinton St., Chicago, Ill. Dept. I received about 175 letters from DX fans (most of whom enclosed a stamp) about my recent com- BAI2AWIK CO. munication to RADIO NEWS, and have answered 111B CANAL STA., them all. I like to correspond with those who CHICAGO, U.S.A. are interested in reception of distant stations. These all hours This Big Book Sent Wholesale schedules may be of interest to listeners: You given are Eastern Standard Time. tc Free Prices CYJ, Mexico City, 410 meters, 1,000 watts: stock and sales vol- 9 to 10:30 p. m., except Sundays. Name Tremendous Havana, Cuba, 400 meters, 500 watts: S ume, with rapid turn -over to the PWX, to 11 p. m., every night. Address thousands of radio dealers we 6KW, Tuinucu, Cuba, 365 meters, 100 watts: serve enables us to make you 11 to 12:30 p. m., Fridays, Saturdays and Sun- worthwhile savings at lowest days. This station has very good carrying power, city wholesale prices. Write for lat- and reception from it is very good. est, new illustrated Catalog "B -1" WKAQ, San Juan, Porto Rico, 322 meters, 9 to 11 p. ni. Wednesday, 10:30 to AUDIO TRANSFORMERS 500 watts: Think of It A 5400 audio transformer- 97C 11:30 p. m. Fridays. a genuine Illinois "all frequency" unit of the fin- HHK, Port au Prince, Haiti, 357 meters, 1,000 est musical capability, offered direct from the factory for only 97e each. A real bargain oppor- Allied Radio watts: 8 to 9 p. m. Friday, 6:45 to 7:15 p. m tunity. Thousands have bought them. Sold with CORP RATION Saturdays. positive guarantee of satisfaction or money back. 711 W LAKE STREET. CHICAGO 500 applied In ratios of 1 y5 to 1, 3 to 1. and 5 to 1 KGBU, Ketchikan, Alaska, 400 meters, Order now. ILLINOIS TRANSFORMER CO. watts: 1 to 3 a. m. Tuesdays, Thursdays and Dept. 108 223 W. Elm St. Chicago, Ill. Sundays. O AX, Lima, Perot, 380 meters, 6,000 watts: your copy reaching you each month. Sub- 6-TUBE RADIO COMPLETE Insure 11 to 12 p. tn. Mondays and Wednesdays, 9 to 534.75 to $65.66 scribe to RADIO NEWS-$2.50 a year. Experi- 11 p. m. Tuesdays and Thursdays. Licensed R.C.A. Circuits. Shielded. One Dial menter Publishing Co., 230 Fifth Ave., N. Y. C. SMZK, Falun, Sweden, 357 meters (will prob- Write for catalog tile discounts to agents ConsumersRadioCo., Dep.151,4721 LincolnAv.Chingo ably be changed to 333 or 315 meters) 2.000 watts, ..,..,.,,,. 1.1111.11 ...... ,...... ,...... e... ummumailli..,..a.a... Please say you saw it in RADIO A E WS www.americanradiohistory.com 504 Radio News for November, 1928 11:30 to 3:30 p. m. daily. There is a chain of 28 stations on the Swedish national programs. "Ravag," Vienna, Austria, 517 meters, 7,000 watts: 3 to 7 p. m. daily. 2L0, London, England, 361 meters, 5,000 watts: 4:15 to 6 p. m. daily except Sundays; then it is from 9:30 a. m. to 4:30 p. m. 5CL, Adelaide, South Australia, 409 meters, 5,000 watts; 3:45 a. m. to 2:55 p. m. daily. 5SC, Glasgow, Scotland, 405 meters, 1,500 watts: 5 a. m. to 5 p. m. daily except Sundays; then 9:30 a. in. to 4:30 p. m. 5SW, Chelmsford, England, 24 meters, 15.000 watts; 7:30 to 8:30 a. m., 3 to 4 and 4:15 to 7 p. m. daily except Saturdays and Sundays. JOCK, Nagoya, Japan, 370 meters, 10,000 watts: 6:45 p. m. to 8 a. m. daily except Sundays; then 7:30 p. m. to 2:10 a. m. EDITION IVA, Auckland, New Zealand, 333 meters, - 500 watts: 10 a. m. to noon, except Sundays; then 9 to 11:30 a. m. MTI, Budapest, Hungary, 555 meters, 20,000 watts, 10 a. m. to 3 p. m. daily. All these stations are of very good carrying power and are receivable in the United States. I am using an NR7 Freed -Eisemann with a TELE VIdICN "master oscillator" of my own design, with 280 volts of "B" and 80 of "C ": a three -stage Magna- (i/aya the ¡or Mefxper/men %ng Ian vox amplifier; a 500 -foot aerial 62 feet high, and 400 square feet of grounding surface. In con- junction with this, I have a three -tube short -wave "TELEVISION" is a magazine pledged to further the art set of my owj, design. I may say in conclusion that I have received from thirty-nine countries on of the infant industry for which it is named, and to supply wavelengths between 5 and 700 meters. I have the "fans" with the latest information and develop- worked about four months on the master oscillator, which can be plugged into any set, and I have ments in this fast -growing field. Television, as a it working now on three different sets. I am always willing to help a DX "ham" who runs up science, occupies the same position today as radio against something that puzzles him. CHARLES J. AEGSTADT, did ten years ago. Like the radio fans of years 420 Pennsylvania Avenue, back, enthusiasts of this new field have had to Bernlmrts, Pennsylvania. ' fight for whatever meager knowledge they FOR EXCHANGE -OR, WHAT HAVE YOU have been able to obtain. This maga- Editor, RADIO NEWS: I am a set builder in my community and I do a zine, then, comes as manna to the in- lot of experimenting on all kinds of sets, cape. information- hungry fan. It is our cially the smaller sets such as the short -wave, reflex and different types of crystal hook-ups with purpose to keep these enthusiasts amplifiers. I have built an Interflex and I will say that it certainly can deliver the goods. I have constantly informed, through added one stage of tuned radio frequency ahead of "TELEVISION," of each the detector, which makes the set more sensitive. I have also built a neutrodyne which will get almost new development. The any high -powered station in the U. S. on any good winter night. second issue of "TELE- I would like to correspond with radio experimen VISION" is now on ters and set builders in other countries, as well as in the United States, to exchange book -ups and the newsstands. ideas on set building. GEORGE' MAKER, You will find be-. 2012 Brainard Ave., Cleveland, Ohio. low a partial In the Television field there list of its in- The first Television maga- are all of the thrills that the teresting zine was published by the radio fan knows so well. Get EXPERIMENTER PUB- 40 Non-Technical on the band wagon with your con - LISHING COMPANY about fellow enthusiasts. Be the tents a year ago. Over 50,000 Radio first in your neighborhood to copies of this magazine, Articles own a television set. Obtain a "TELEVISION," have since every month for the beginner, the layman copy of "TELEVISION "; been sold. This, alone, is and those who like radio from the non- it will show you how to build sure proof of the popularity technical side. a real Television receiver. of this interesting new art. SCIENCE AND INVENTION, which can be bought at any newsstand, contains the largest and most interesting section of Partial List of Contents radio articles of any non -radio magazine in existence. New Jenkins Radio Movies Practical Demonstrations Scheduled for Station WRNY New Belin Photo Transmitter Campbell Swinton Television System Vacuum Cameras to Speed Up Television Quartz Crystals Synchronize Television Sets Plenty of "How to Make It" radio arti- Infra -Red "Eye" Sees at Night Baird Optical Lever Increases Speed cles and plenty of simplified hook -ups for Valensi Television Recording Pictures with Air Jet the layman and experimenter. The radio Connection of Photo -Electric Cell How to Build a Radio Photo Recorder section of SCIENCE AND INVENTION and many other articles of equal interest is so good that many RADIO NEWS readers buy it solely for this feature. Radio Articles Appearing in AT ALL OR WRITE NEWSSTANDS THE25CCOPY DIRECT November Science and Invention Magazine BUILD "S. & I." EXPERIMENTER PUBLISHING Co., INC., 230 Fifth Ave., New York, N. Y. HOW TO THE TELEVISION RECEIVER EXPERIMENTER PUBLISHING COMPANY, INC. PLANE BROADCASTS RADIO PHOTOS 230 Fifth Avenue, New York City, N. Y. MID -OCEAN RADIOPHONE Gentlemen: Please forward to me a copy of TELEVISION. Enclosed find 25 cents. A TRIPLE DYNAMIC SPEAKER AN ALL- ELECTRIC RECEIVER Name NEW RADIO DEVICES RADIO ORACLE Address City State RADIO WRINKLES LATEST PATENTS i Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 505 I Want to Know CCELL, O (Continued from page 464) a in a 199 tube. \\'hen the set is in operation, the Radio Consoles rheostat should be turned back as far as possible Combination Phono -Radio Console for without reducing the volume. If an adjustable Cle -Ra -Tone all standard sets, either A.C. or D.C. crystal is used, adjust it until a slight hiss is beard in the headphones. The tuning is accomplished by turning the condensers Cl and C2. 'l'hey should now be turned until a station is heard, and the Radio crystal should then be readjusted for maximum volume. As explained above, the connections to the secondary of the transformer should be reversed, and the position found to give better results should Sockets be used. If no signals are heard when the set is tried, the first place to look for trouble is in the crystal detector. The crystal must be adjusted to a sen- sitive point and, if no signals can be heard when it has been adjusted a number of times, place a new crystal in the receiver. The next point to look for trouble is in the batteries and the aerial and ground. Test the batteries with a voltmeter or take them to a local dealer, who will have the facilities for making these tests. Look over the aerial to make sure that it is well insulated and, if possible, try another set on it to be sure it is in good condition. Finally, if no stations can be picked up, check the connections and, if no poor contacts or mistakes are found, take the set to your radio dealer or a friend and have him look it over and test the apparatus. The two dials should read almost alike, if not exactly so. The only other adjustment to be made sV is that of the filament rheostat. Turn the knob on this resistor until the signals are as loud as pos- Specially Designed sible, but do not make the tube burn too brightly, for Excello Combination Phono- since this will shorten its life considerably. Radio Console Model R-44 A. C. Detector Tubes Completely equipped: GE Elec. phonograph motor, etc., and switch from phonograph to GRID LEAKS radio. Receiver compartment is a sliding Spring supported, shock absorb - drawer 24 in. x 9 in. x 14 in. Cabinet, wal- (2312) Mr. J. M. Johnson, Andover, Mass., ing. The tube -holding element nut throughout, with fancy butt walnut writes: veneer doors. (Q.) "What is a 'grid leak,' and why is it "floats" on perfectly balanced At your Dealers, or write for complete used in the grid circuit of the detector tube of springs. Reduces microphonic catalog of full line. my set? I should think that a resistance in the disturbances, tends to lengthen EXCELLO PRODUCTS CORP. grid circuit of the tube would have a tendency to reduce the volume of the music. Will you life of tube, and lessens the possi- 4832 W. 16th St., Cicero. III. (Suburb of Chicago) please explain the reason for its use ?" bility of short -circuiting closely - (A.) A grid leak is a high resistor, connected between the grid terminal of a detector tube (or spaced tube elements. an amplifying tube) and some part of the filament circuit of the tube. Grid leaks are usually rated Y -Type, Green Top, for 5 Prong Your Set Can according to their resistance in megohms or in A. C. Tubes: for mounting on Now Get fractions of that unit; the megohm is equal to top of panel, $1.00; for direct Waves 1,000,000 ohms. One of the chief difficulties with Short grid leaks has been the uncertainty of their re- attachment to panel, 75c. Sent anywhere In the U. S. sistance. post paid upon receipt of Red Top, for UX price. Canada and Foreign, 'Many kinds of grid leaks have been used; the Standard 60e additional. Money or- Type Tubes: For mounting on dr only. Also sent original type consisted of pencil marks on a piece C. O. D. plus P.O.W. in of paper between two contacts. Naturally this top of panel, 75c.; for direct U. S. If $1.00 accompanies attachment to panel, 50c. order to insure carrying type of grid leak was affected by moisture in the charges. In ordering be air and changes of temperature. A more recent sure to name set and tubes type is made of a piece of fibre impregnated or used, such as UV109. A t all Radio and Electrical U X199. W D1t, 201A. U X226 coated with some form of carbon, mounted in a or UY227. Price 515.00 or short length of glass tubing, and fitted with metal Dealers and Jobbers 917.50 for A. C. Sets. ends, which make contacts with two spring clips. The SUBMARINER Leaks of this type are quite satisfactory, if they are will convert your regular set into a short-wave receiver by simply air -tight so that moisture cannot enter. Benjamin Electric Mfg. Co. Inserting a plug In place of one of the tubes. This takes but a few The most recent type of grid leak consists of a seconds. With "Submariner" it will enable you to tune between 20 and 65 meters. piece of glass tubing, on the inside of which has 120 -128 S. Sangamon Street This device operates with all sets such as T.R.F., N eutrodyne, been deposited a layer of resistant metal, which acts Super -Heterodyne and others A C or D C operated. No addi- Chicago tional tubes. batteries, or colts required. It set operates a as the conducting medium. Another variation of speaker it will do so with "Submariner" attached. Operates this metallic type has the coating on a piece of New York San Francisco as a wave changer with Super -Heterodyne and as detector unit with others. insulating compound inside the tube. 'l'he resist ance of these grist leaks is much more constant 247 W. 17th St. 448 Bryant St. SHORT -WAVE RECEPTION types by %catching Is practical, as short waves penetrate better and there Is lees than that of other and, carefully static. The "Submariner" waveband includes practically the amount of metal deposited, the resistance values all powerful stations which broadcast programs. You may can be made much more accurate. _f also listen to amateurs from all parts of the world who transmit code messages. You will have one of the most efficient short- wave receivers when the "Submariner" is attached to your Grid Leaks and Detectors set. Get a "Submariner" so you may have command of the The purpose of the detector's grid leak is to --+ short-wave activities as well as the broadcast band. Never assist in the control of the "grid bias" of the CHI - RAD before has so much In radio been offered for so little money's A new thrill awaits you! If your Dealer does not carry detector tube, and also to allow dissipation of the ORDER TODAY DIRECT excess negative charges (electrons) that accumulate New 1929 Catalog This dories has been nationally advertised, and sold In all parts of on the grid of the tube. Although detection can Ills world for the past two years be obtained without a grid leak, by correctly bias FREE to Set Builders J -M -P MANUFACTURING CO., INC. ing the detector tube, this method is not nearly Includes Complete Parts for 3401 Fond du Lac Ave. Milwaukee, Wis., U. S. A. as sensitive as the grid -leak method and, for this reason, has not gained much favor. (See the an- H. F. L. ISOTONE swer to Q. 2272, "What is Detection ?" on page 1151 of RADIO NEtt's for April, 1928.) New TYRMAN "80" The proper value of the grid leak depends both MADISON -MOORE "AC" on the type of tube employed and on the strength \\NEWSto Set Builders of signal being received. It also depends, to sonic NATIONAL B. D. "AC" on the tendency of the receiver to oscillate. Barawik offers set builders bigger extent, New THORDARSON bargains - bigger opportunities to make When very weak signals are being received, a very Power Amp. money this season. New sets, new kit high -resistance leak should be used, in order to ideas, all the leading parts, dynamic Discounts for Set Builders speakers, supplies. etc. Lowest rock- get the greatest amount of volume. However, when bottom prices. Bigger quicker loud signals are being received, a rather low re- Sl Bargain Chicago Radio Apparatus Co. todas sistance must be used to maintain good tone qual- 415 S. Dearborn St., Dept. RN, Chicago BABA VIa. CO., CNCAGO.US.A. ity. From this explanation, it can be seen that a compromise value must be chosen, to give good Please say you saw it in RADIO NEWS www.americanradiohistory.com 506 Radio News for November, 1928 quality and sufficient sensitivity. A variable grid leak may be used; but most of them are unsuit- able because of their tendency to make the set 0)THFR noisy, and set owners usually try to avoid adding another adjustment. If the grid leak has too high a resistance, the receiver will howl and block coWYEW without much provocation. The blocking is indi- cated by a series of popping noises either fast or slow, depending on the value of the leak and the other constants of the circuit. -against 30 seconds If the resistance of the grid leak is too low, the distant stations will be weak, or entirely absent. to a minute for other It may also be found difficult to make the set tubes Arcturus 127 regenerate and, when the regeneration point is -the reached, the set will suddenly drop into oscillation. A -C Detector Tube! Put \\'ith the "bard" tubes (such as the 201A, 199, an Arcturus A -C Long Life and 112A) a grid leak with a value of between 2 and 5 megohms will usually be found satisfac- Tube in every socket for tory, at wavelengths in the broadcast range. The gaseous tubes (of the 200A type) will also use a quicker action, better tone, value within this range; while the old -style soft better volume, longer life tube (similar to the L' \' -200) required a value of about %- megobm. However, the best value for and immunity to line surge. the grid leak in a particular receiver can only be 'k found by experiment. Complete line of Arcturus Dr.Lee Grid Leaks in Amplifiers low voltage Tubes : 126H, Grid leaks, or grid resistors, are used also in 126, 071H, 071, 127 amplifiers of certain types. In the choke -coil- and and resistance- coupled amplifiers, in which the stages 180. are coupled through transformers, the grid must be supplied with the correct bias. In order to 4 keep the "signal" (- \.F. or, sometimes, R.F.) in Arcturus Radio Company - an With the same creative enthusiasm the correct channel, it is necessary to use 255 Sherman Ave., Newark, N. J. arrangement which will allow the direct -current that produced the first radio vacuum the tube (1906) potential of the "C" battery to be placed on Dr. DeForest has now grid, but will not short- circuit the signal current. developed the perfected Audion. V This may be accomplished by the use of either a When you replace your tubes with choke coil or a resistor of the correct value. Since DeForest Audions you will exper- the latter is much simpler and cheaper, it is used ience a new enjoyment in clarified more frequently. reception. The bias applied to the grid is determined by Send today for your free copy of the value of the leak and method in which the is to filament circuit. If it the interesting booklet by the resistor connected the "Father is connected to a "C" battery, the biasing voltage of Radio." depends on the potential of this battery, of course, as well as on the resistance of the grid leak. When the grid return is connected to the negative ter- minal of the filament circuit, the bias is derived Mea.' Deforest Radio Co. and it is necessary to use from the "A" battery, Vrfe.awwr; the correct resistance in the grid leak in order to " ' Less Static JERSEY CITY ^. N.J. have the tube correctly biased. The latter method Bring Your Set to is often employed in the first stages of an amplifier SharperP TuningS Maximum Sharpness FOUÑDED 1899 where the grid voltage does not have to be very IN EVERY HIGH GRADE CIRCUIT TODAY high. MODEL "N" VARIO- DENSER-Micrometer ad- justment easily made, assures exact oscillation control. Quick, easy tun- ing, more volume, clearness and sta- bility. Capacity range 1.8 to 20 I Our micro-micro- OM Novemberer Issue: farads. Price 81.00. The World at Bay, by B. and G. ModelO Learn Wallis. Part I. Application of Made fn 3 sortable capacity ranges; fnfee. each. S1 50. the fourth dimension, in this lead, to Earn story, enables the travelers to F REE ofall guiWrite today forecopy. make a journey to the moon and $60 to back and around the earth in $200 a an astoundingly short space of time. Our new authors have given us a carefully XLAadio Laboratories week! studied treatment of the subject of inter- Learn on Actual Electrical planetary travel, cleverly interwoven with Dept. A, 1224 Belmont Ave., Chicago, III. Machinery in 90 Days romance and human psychology. Get into Electricity in 90 days. Learn by work In the Brat roaring shops Coyne. The Ananias Gland, by W. Alexander, Nactual of ot Corres onaence School. All practical the of - experience on full-elm electrical machinery. New What determines extent our truth 92000.000 school with vastt new electricala ma- fullness.'. It might very well be glandu- chinery. You don't need eededuatioo of experience. We Will Assist You To Part. Time Job lar action some kind. Mr. Alexander hl aarning And Free Employment Service For cleverly works up an idea of extreme in- 1000 HOURS Life Graduation. Special offer for -of the Best omot Cores extra terest. Act now -get big free book. The Psychophonic Nurse, by D. H. Keller, Fun You Ever Had -Get Your EPaulina COYN lintr t M.D. Instead of contenting himself with ELECTRICAL SCHOOL the conception of new mechanical labor- Of e ©pt 88 777. saving devices -generally involved in the Copy SAM LOYD'S human scheme of life -Dr. Keller always goes further. He gives us, in a perfectly Tricks and Puzzles natural manner, the ultimate psychologi- H. C. Lewis, Pres. cal effect of his mechanical innovations, ÑCoyne Electrical School, Dept.88.77 on the human being. Though he never de- The year's most unique book, contains stroys-or even temporarily puts out of com- South Paulina St. Chicago. 111. 120 pages that crammed ar H.. C.: Please send me free your big rata- mission -his newly developed apparatus, are full of all n log and full particulars of your special offer. we are glad, when we finish the story, a that we are still a little ahead of the in- kinds of tricks, puzzles, games, conun- k Name vention. li drums, etc. b Address The Eye of the Vulture, by Walter Kately. B The human eye is limited in its vision C Torn[ St of*. of the colors of the spectrum, just as the Size, 9 x 12 inches-illustrations on every ear is limited in its range of sound ap- preciation, and it must differ drastically page. Fun for every member of the from that of animals, birds, insects, etc. A bird, for instance, may not see all we family. Elections have brought back Custom do; on the other hand, many things within Set building. Business is booming. the bird's visual range may be completely 50e On All Newsstands Thousands of old -timers are clean- out of ours. In this story, a number of ing up. Let Barawlk show you thei theories, novel and interesting, but seem- EXPERIMENTER way to bigger profits, more sales. ingly founded on scientific grounds, are PUBLISHING CO., Inc. Send today for Barawlle's Big Bar- introduced. 230 Fifth Avenue, New York, N. Y. gain Book - the radio man's bible. And Others. BARAWIK CO. 2118 CHICAGO,Ü A, A, Please say you saw it in RA110 NEWS www.americanradiohistory.com Radio News for November, 1928 507 Radio News Laboratories NEW! 90 Volt (Continued from page 461) THE MIRACLE OF - vides a resistance of approximately 150.000 ohms _-_ in the plate circuit of the tube. A high value of . inductance is used in the grid circuit of the suc- THE RADIO WORLD! ceeding tube, which gives a step -up ratio through Ir the use of the grid inductor as an auto -transformer. Newest Guaranteed 7 -Tube The plate the preceding tube is cou pied output of 1 -Dial Console S_ et -Worth $200 to the primary tap of the auto -transformer -coupled 1929 grid inductor through a capacity of such size than BUY .t4 DIRECT A a MODEL excellent amplification is obtained between 30 to 5,000 cycles. The iron -core inductor, plate resistor and coupling condenser are encased in an iron housing of black enameled finish, 4 inches high. with a base 3!i x 31 inches. Excellent quality A BIG COMES and volume, with great amplification, was obtained VALUE COMPLETE when the unit was tested in a screen -grid, space - charge A.F. amplifier. A WARDED THE RADIO NEWS LABORA- ALL ELECTRIC RADIO TORIES CERTIFICATE OF MERIT NO. 2435. 30 DAYS' FREE TRIAL! Positively Eliminates 1 Hums, Line Noises, etc. A Wonder .75 GRAPHITE (IN SUSPENSION) Greater Volume and Bargain! Clarity Guaranteed ". \quadag," submitted by the Acheson t liblac Company. Port Huron, Mich., is a concentrated Buy direct Non -arid and noiseless. All detector and intermediate colloidal solution of artificial (electric -furnace) from factory. voltages plainly marked. Simpler to hook up than dry ills. Operates 1 to 12 tubes. If not thoroughly satis- graphite in water. which has found successful use 9200 fied return after using 30 days for complete refund. ill the manufacture of resistance elements for grid- VALUE t :uaranteed further 2 years. For 110 -120 volts A.C. 25 to 60 cycle current. 90 volts. $12.75: 1125¢, 315.25; leaks and variable resistors. It has been used also Outperforms 185. 517.50: 157iy. $19.50: 180, 324.00:2025 326.00. sets selling at Uso built for D.C. current 110 and 32 volts at only S:S.00 additional, any size above. Ample stocks -same 2 and 3 times day shipments. Simply say-ship C.O.D. or write for our low price. my interesting literature, testimonials, etc. Includes con. sole shown, B. HAWLEY SMITH made of com- 334 Washington Ave., bination wal- Danbury, Conn., U.S.A. nut; A. C. electric set, all tubes, built -in mag- netic speaker and aerial ARTE equipment, PARTS as a dry lubricant for condenser bearings and for COMPLETE FOR NEW A. C. CIRCUITS USED the drawing of tungsten wire. It has been used BY LEADING SET MANUFACTURERS ill tube manufacture as a "Getter." as an opaque Nothing Else to Buy coating in the manufacture of photoelectric cells, Tone! and has been found, as well, useful in establish- Powerful Reception- Amazing W ing positive electrical contacts, and as a conductive Remember -30 days free trial. , You be the judgct orth 5200 and looks Itt Only one dial to tune- uluminatedl Carter Center Tapped coating for electroplating. It has many other appli- Marvelous mellow tone. Selective and gets distance Resistors Small, com- cations, and is suitable for uses of the manufac- easily. The radio sensation for quality. price and per- pact, rugged. Guaran- turer, either the above- named, or wherever conduc- formance. Mail coupon today for our big, Money-Saving teedwithin 3 per cent. Free Catalog, befor you uy any radio accessories! 8 different types. 6 to tive material of this type is needed. 60 ohms. AWARDED THE RADIO NEWS LABORA- Our New FREE TORIES CERTIFICATE OF MERIT NO. 2436. Battery Sets Catalog -Just Carter IMP Power Our low factory prices on Published -Shows Switch. Self-contained. the complete line of Dia- double contact, post mond Electric and battert, You How To Uve, for 6 volts fila - R.F. CHOKE operated radios shown in ment or 110 volt A.C. catalog will amaze youi SAVE HALF! Circuit. The R.F. choke coil shown, submitted by the Hammarlulul Manufacturing Co.. 424 W. Carter Adjustable Write for 33rd Diamond Radio Company 1 Resistors. 'rho Ideal Catalog of Street, New York, N. Y., is of the helical -winding w A. C. Hum adjustor Complete Line Dept. =IS 1120S. Clinton St., Chicago, III. for mounting on sub - type. It was found to have an inductance within panel. 6 to 20 ohms. Any dealer mn supply 10% of its rated value, 85 millihenries, when meas. MAIL THIS COUPON TODAY! tired at 1,000 cycles. The D.C. resistance, as arter Radio measured, is 2,000 ohms. The distributed capacity Diamond Radio Company, Dspt.2114 Ce-tiCAGO Col was found to be extremely small, in comparison 820 S. Clinton St., Chicago, III. with the inductance. The coil is contained in a Please Send me your Free Catalog of Diamond molded black bakelite housing, 1y, inches high, and radios and details of your 30 Day FREE Trial offer requires a base space 1% x 2 inches. Name AWARDED THE RADIO NEWS LABORA- Address TORIES CERTIFICATE OF MERIT NO. 2437. , City State 1 Wholesale Prices Here you will find a new up -to- Newest Radio Hook - Ups date stock of kits, parts, acces- sories and sets -everything you - Free - want in radio. Write for catalog Send now for the newest radio hook -up book. quoting special dealer's Shows how easy it is to bs lid remarkable new A.C. "B -1" and D.C. receivers of longest range, greatest vol- wholesale prices. ume, purest, clearest tone, and super -selective. Also shows how to make short -wave receivers and SHORT -WAVE TUNING CONDENSER adapters, how to use new screen grid tube In A.C. and D.C. circuits, how to build power amplifiers and The short -wave condenser (Type ML -7) shown, A -B-C eliminators. Latest information on all new submitted by the same manufacturer, is a 7 -plate radio wrinkles. Send for free copy now. AIIied of the midline- frequency low -loss type. CORPcJoR.CCI-ION condenser KARAS ELECTRIC COMPANY 711 W. LANE STREET, CHICAGO It has a sturdy cast -aluminum frame supporting the stator, and drilled for base -board or sub -panel 4038L3 N. Rockwell St., Chicago. U. S. A. mounting; two flat -head screws are provided on the front of the frame for panel mounting also. Name The stator plates are soldered to plate- spacing St. and No mounting brackets which, in turn, are fastened to City and State S incotho dew of Itedio. Barawik lase been known the world the Bakelite insulating strip. e hendoeortere for .et builder, and luna alas. under one cool, u everything;thine you seed -let e. parte. The stator plates are provided with a spacing au optdayyour arrivduet s -reed oehip to youths and the stator assembly is supported ,p y. Barewik ui bar entire semi.imam. me. Baraw,k from the bottom of the frame. The rotor is of the derive largest chnndieealw Y alespleases. A rmali neatisaed profits know and B is Best." Let us send "floating type"; which allows the removal of the heed certain simple you tihecBig ydarawik Book tree and prove itto the of the condenser in a IN VENTORSwhobut vital facts zisee CANAL STA., shaft, and operation before gang. The bearings are of the cotte type, and the applying for Patenta. Our book Patent -Sense gives those B11.ARAW I K CO. cwICA60. u. s. A facts: sent tree. Write LACEY & LACEY, 631 F St. rotor - is provided with maximum and minimum Washington, D.C. Established 1663 Please sap you saur it in RADIO NEU'S www.americanradiohistory.com 508 Radio Nevi's for November, 1928 stops and a pig -tail connection; its plates also are held rigid in position by a spacing bar. A friction brake is provided which operates on th'e removable shaft. The condenser has a maximum capacity of SAVE YOUR MONEY ! 140 mmf. (.00014-mf.) and a minimum capacity of 15 mmf., and is of excellent electrical and mechan- BE YOUR OWN SERVICE MAN New! ical design. AWARDED THE RADIO NEWS LABORA- THE RADIO Super MasTennA TORIES CERTIFICATE OF MERIT NO. 2438. TROUBLE THE RADIO FINDER MICA BALANCING CONDENSER TROUBLE FINDER Even the highest - The small seini -variable condenser ( "Type priced radio set EC -70) shown, submitted by the liammarlund Manufacturing Co., 424 W. 33rd St., New York, occasionally de- N. Y., is of the mica -dielectric type and designed velops a fault and for neutralizing or balancing radio-frequency cir- that at a time cuits; it consists of two plates riveted to a rec- when you least tangular piece of bakelite, 1 Vt inches long, 11/16- expect it -maybe inch wide, and 3/32 inch thick. The stationary right in the mid- plate is a flat piece of brass, provided with a dle of an interest- ing program. But, a handy copy of The Radio Trouble Finder is the sim- ple means for tracing every defect and remedying it in the easiest manner tongue pierced by a 1 -inch hole for fastening to possible. There is no mishap that could a terminal of a socket or tuning condenser, etc. befall a radio, but what is fully covered The movable plate is of spring copper and sepa- in this valuable book. rated from the stationary plate by a rectangular The Radio Trouble Finder is edited piece of mica which is riveted to the latter; the men capacity is adjusted by a brass screw which turns by fully versed in the subject into a tap in the center of the insulating support. covered -men with years of actual ex- The maximum value was found to be 15 mmf. and perience behind them -and who have the minimum 6 mmf. grown to prominence since the infancy AWARDED THE RADIO NEWS LABORA- of radio. TORIES CERTIFICATE OF MERIT NO. 2439. Don't wait till your set goes bad -get your copy of this remarkable guide to FILAMENT TRANSFORMER radio trouble now. Fill in the coupon The "Dependable" A.C. filament transformer and we will send you by return mail a shown, submitted by the Leslie F. Muter Co., 76th copy of The Radio Trouble Finder, and Greenwood Ave., Chicago, Illinois, operates a money -saving investment. You can from a 110 -volt, 60 -cycle circuit. The transformer be your own service man. is of the step-down type and supplies filament cur- rent for the operation of 226 -, 227 -, and 112- or 171 -type vacuum tubes. It has three secondary The Copy Brings to windings for 2, 3, and 5 volts, which are to be 25C Good News used in connection with suitable filament -regulating the Radio World! BUILD YOUR OWN A Vertical Aerial RADIO SET is practical, that efficient, and 150 RADIO reliable e(eeeee)3 HOOK -UPS Gets stations, increases the selec- This is the latest tivity and signal strength. resistors. The 3- and 5 -volt windings are provided issue of this re- with a center tap, while the "nodal" point of the markable book. Approved by 2 -volt winding is obtained by an external center - Absolutely new tapped resistor. A 6 -foot cord, fitted with a stand- and up - to - date. Prominent Radio Engineers ard plug, is attached to the primary winding and All the best cir- allows direct connection to the house -lighting cir- cuits of the day. Sold by large Jobbers and Dealers cuit. The iron housing is 4 inches high, with a base 31 x 31 inches over all. The transformer Full instructions Write for FREE BOOKLET is of efficient design and its operation was found on how to build. to be satisfactory. Make your own AWARDED THE RADIO NEWS LABORA- set from the dia- Gustin-Bacon TORIES CERTIFICATE OF MERIT NO. 2440. grams shown in Manufacturing Company 150 Radio Hook - Ups. Write today -pick the set Dept. 1128 -N Kansas City, Mo. SOCKET ANTENNA PLUG you want to build and make it. Then The "socket antenna plug" shown, submitted by you are sure to be satisfied with the the Clarostat Mfg. Co., Inc., 285 North Sixth St., results you get. Brooklyn, N. Y., converts the house -lighting circuit into an aerial for the radio receiver; it consists 150 Radio-Hook-Ups was prepared by of a nickel-plated metal cylinder, 1 inch long and the staff of Radio News. An accurate MR RADIO MANUFACTURER 11/4 inches in diameter, one end of which is fitted guide to better set construction for the with two prongs for plugging into a standard radio "fans." EVERYTOWN, U. S. receptacle, which in turn is screwed into the light socket. The other end of the device is provided FOR THE RADIO TRADE The Copy We maintain a complete, up -to -date mail- 25C ing list of U. S. radio dealers' names which is continually revised and en- MAIL THIS COUPON NOW larged. These names are on stencils and ready for you to use with your next CONSRAD CO., INC. dealer mailing. Write us for further 230 FIFTH AVENUE NEW YORK, N. Y. information. EXPERIMENTER PL'Bf.ISHING CONSRAD COMPANY, INC. COMPANY 230 Fifth Avenue, New York, N. Y. - 230 FIFTH AVENUE, NEW YORK, N. Y. Gentlemen: Kindly send me a copy of 150 RADIO HOOK- UPS ..THE RADIO TROUBLE FINDER... with two discs of hakelite which are clamped to (check which or both). Enclosed and cents in lull payment. the cylinder by a single rivet in their to Quality center; Apparatus which is soldered a rubber- covered cord approxi- Name Our latest bulletin No. 929 describing our com- plete line of quality apparatus is yours for the mately 12 feet in length, provided for connection Address asking. Write for it today. to the receiver's aerial binding post. The meas- GENERAL RADIO CO. ured capacity of the device was found to be .0011- City State 80 State St., Cambridge, Maas. mí.; the condenser is connected to only one prong, Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for November, 1928 509 thus being placed in series with the receiver's aerial coupler. To obtain operation in some cases, it may be necessary to reverse the position of the Price $15.00 plug in the socket. The operation of the device is found to be satisfactory. AWARDED THE RADIO NEWS LABORA- TORIES CERTIFICATE OF MERIT NO. 2441. SELF -ADJUSTING A.C. RHEOSTATS The ".mperite" (Type 226 shown), submitted by the Radial) Company, 50 -52 Franklin St., New York City, has been designed for use as a ballast in series with the Marnent of a 226 -type tube, when operated from a step- down- transformer sec- ondary supplying approximately 2 volts. Its re- sistance varies with the current flowing through the circuit; at 1 ampere its resistance is 0.5 -ohm and, at 1.5 amperes, 1.83 ohms. When this . \mperite is used in series with a 226 -type tube (whose normal operating requirements are 1.05 If you insist on amperes at 1.5 volts) it requires a transformer' AMAZ ING secondary voltage of 2 and a current value of I the best, they must ampere. AWARDED THE RADIO NEWS LABORA- REGULATION hand you Tele- TORIES CERTIFIC. \TE OF MERIT NO. 2442. OF A. C. VOLTAGES vocals. All stand- with the new WEBSTER ard types. Ask for them at your AUTO -POTENTIALATOR VDU can now obtain an A. C. voltage even dealers. submitted also for test 1 regulator that delivers an absolutely The same manufacturer flow of A. C. current to your A. C. receiver or the Type 227 :\mperite, which is designed for use "A" and "B" eliminator. The Webster Auto- in series with the Marnent of a 227 -type tube, Potentialator is a new automatic device that when it is operated from a transformer -secondary has amazed every user with its perfect regula- voltage Televocal Corporation supplying 3 volts. The ballast resistance at 1.5 tion. It not only delivers the proper on the normally high or low line, but also amperes is 0.2 -ohm and, at 2 amperes, 0.43 -ohm. fluctuations Televocal Building 227 -type tube, effectively controls the sudden When it is used in series with the common to all A. C. lines. Dept. A -4 a transformer -secondary output of 1 at 3 volts is required for normal operation. Contains No Tubes or Liquids 588 12th Street NEWS LABORA- AWARDED TIIE RADIO The Webster Auto-Potentialator contains no West New York, N. J. TORIES CERTIFICATE OF MERIT NO. 2443. tubes or liquids. It is entirely automatic in operation. Its use will protect your A. C. FILTER CONDENSER tubes from burnout, and greatly lengthen (Type R171 shown) sub- their lives. The filter condenser When you hook a Webster Auto-Poten- mitted by the Acme Wire Co., New Haven, Conn., tialator onto your receiver you do away with has been designed for use in "B" power units of all voltage -fluctuations and can sit back and the "Thordarson R171 Compact" type, using a enjoy the most marvelous reception you ever gas -filled rectifier. It has a continuous D.C. volt- listened to. It assures uniform reception, ear cae Condenser sections of 8, 2, wonderful tone clarity. and tremendous e age rating of 400. any of the variations so respectively, are provided; volume, without Quality Tubes 2, 1 and 1 mf. Capacity, common in unregulated A. C. sets. the 8- and the 2 -mf. terminals are placed upon the top, and the two terminals for the 1 -mf. sections Order TODAY direct from at either side. The common terminal (negative) advertisement is at the right. The five sections are this of the latter you are in a metallic container, together with an If your dealer is out of stock and placed in a hurry, you can order your Webster Auto- Potentialator direct from this ad. Just nu out - the coupon below, inclose $15.00. and mail to us, and we will ship your Auto- Everything in Potentialator the same day we receive your order. Order TODAY -end your voltage Radio at Wholesale fluctuation troubles NOW. We supply every radio need from our mammoth stock of kits. The WEBSTER CO. parts and sets of latest design. 858 Blackhawk Street Lowest wholesale prices. Expert CHICAGO attention; immediate service. Write for big, illustrated Cata- COMPANY THE WEBSTER Ill. log "B -1. 858 Blackhawk Street, Chicago, Send me a Webster Auto-Potentlalator as ad- vertised in "Radio News." I enclose 515.00. Name insulating compound, and hermetically sealed; the metal can is 2 inches thick, 4i4 inches wide, and Address when 711 W. LAKE STREET, CHICAGO 5 r inches high. The respective sections, City State measured, had capacities within 10 per cent of their rated value. When the filter was used in connection with the R171 compact, a humless "B" power supply was obtained. Be RADIO OPERATOR AWARDED THE RADIO NEWS LABORA- New Karas Short -Wave Kit an Expert NO. 2444. Fascinating work. Wonderful opportunities. TORIES CERTIFICATE OF MERIT ! Good pay. Mordent Code Sender teaches you 'TITIp Reaches Around the World at home in halt the usual time. Reproduces acrrml New radio thrills await you. Listen to Australia. messages, Europe, Asia. Tune in on the world's airplane sending of expert operators. Sends you rl IMPROVING THE OLD SET radiograms, etc.- regular code traffic flyers. ships at Sea: in fact, the whole world. You anywhere, any time, any speed. U. S. Editor, RADIO NEWS: can do it easily with the remarkable Karas Short - Navy and leading schools endorse Tele- issue "Improving re- Wave Receiver. You can't know the fascinations plea as The article in the July of radio until you experience this new sensation. is along the right wave to new e instruction á óled a,wt extrarra ception on a slim pocketbook" Karas engineers have developed short cost. Write for Booklet Nit. the B.C.L. with the old sets to of perfection. build. Easy tune lines. Help with art tto rio. se TELEPLEX COMPANY reception, and don't forget the beginner built like a One watch. St.. New York, N. Y. get better famous Karas condensers, 76 Cortlandt hints now and then. I shunted the Raras coils and audios -the world's standard. with a few Send now for full information and construction grid resistor on the middle dial of my Atwater blueprint -Free. Kent 20, increasing the volume materially on sta- KARAS ELECTRIC COMPANY tions coming in below 50 on the dials; and as my 4038L4 N. Rockwell St., Chicago, U. S. A. model is a late one with provisions for a 171 tube and "C" battery I did not have to follow Name in the balance of the article. Radio has been changing so fast the instructions St. and No Also, I wish to commend your items against lately that its hard to keep up State with it. Barawik's Big Radio Guide the pure and simple fakes offered by some dealers City and will keep you posted on the newest to the radio public. This is a real service to the wrinkles. Thousands of Illustrations buying public and should be continued in an effort of sets, parts, new Ideas. Big chance to month. Sub- save big money. Send for free copy now. to remedy the condition. Insure your copy reaching you each CH E. B. CLARK, to RADIO NEWS -32.50 a year. Experi- scribe N. Y. BARAWIIC CO., CAGO i=S.A. 724 East 41st St., Baltimore, Md. menter Publishing Co., 230 Fifth Ave., C. Please say you saw it in RADIO NEWS www.americanradiohistory.com 510 Radio News for November, 1928 OPPORTUNITY AD-LETS Follow these advertisements every month. Reliable advertisers from all over the country offer their most attractive specials in these columns. Classified advertising rate twenty -two cents a word for each insertion. Ten per cent discount for 6 issues, 20 per cent discount for 12 issues. Names and addresses must be included at the above rate. Cash should accompany all classified advertisements unless placed by an accredited advertising agency. No advertisements for less than 10 words accepted. Objectionable or misleading advertisements not accepted. Ad vertisements for the January issue must reach us not later than November 1st. { CIRCULATION LARGER THAN THAT OF ANY OTHER RADIO PUBLICATION EXPERIMENTER PUBLISHING CO., INC., 230 Fifth Avenue, New York, N. Y. - - CA gents Wanted Instruction Printing, Engraving and Multigraphing Letters anyone can un Guaranteed Genuine Gold Leal put Men -Qualify for railway postal clerk, internal revenue, 200 Letterheads and 100 Envelopes, enormous demand. Free aiI $1.10, postpaid. store windows. Large profits, tallier and outdoor positions teady work ; particulars Oberman Company, Dog 1208, Chicago. samples. Metallic Letter Co., 922 N. Clark, Chicago. , C. Write 3lkane Inst., Dept. B -32, Denser, Colo. Multi graphing, two dollars thousand. Miscellaneous Printing. Slayer Rey Corporation, 3ionntouth, Illinois. oAgents -We start you in business and help you suc- Learn Chemistry at Home. Dr. T. O'Conor Sloane. Cr ceed. No capital or experience needed. Spare full time. noted educator and scientific authority. will teach you. mum anon. nn,...... m,n...umanunn.m, -$100 Madison Products, ::::...... nuunmm..... eYou can earn $50 weekly. Write Our house study correspondence course fits you to take a 560 Broadway. New York. position ns chemist. See our full -pace ad on page 973 p"I this issue. Chemical Institute of Sew York. 16 E. 30th oStreet, New York Printing Outfits and Supplies nsdCity. eBooks nPrint Your Own Cards. Stationery, Circulars, Adver- eHelp Wanted tising. etc. Complete outfits. $8.85 ; Job Presses, $11. $29: Rotary, $119. Print for others; big profit. Easy rules Books, Magazines, Art Publications in French. Spanish furnished. Photo novelties, samples, lists, etc.. 20 cents Write for Catalog Presses, Type. Paper, etc. English. Kelsey Company, J -13, Meriden, Conn. cstamps. Vitlaverde Co., Dept. 211, Box 13229, Havana, Firemen, Brakemen, Baggagemen (white or colored), Cuba. Sleeping Car. Train Porters (colored), $130 -$250 monthly...... a.nm ...... nnaanmmnnav,.,,....,..,.,,.vna.,nnuua,..,,.,.,...,.,,....,.,,....,,.,.,,:. Experience unnecessary. 237 Railway Bureau, East St. Louis, Ill. M Radio Business Opportunities Miscellaneous Wanted : Men to work with National Radio Senice Inventions Commercialized. Patented or Unpatented. korganization. No selling scheme. Radio Doctors, Inc., rept. .rWrite Adam Fisher 31fg. Co., 278 Enright, St. Louts, 310. Inventions Commercialized. Patented or Unpatented. N. Essex St., Salem. Mass. eaWrite Adam Fisher Mfg. Co.. 278 Enright, St. Louis Mo Book. Order business. Hadwil, A -1 five tube seta rFree Start little Mail Forms to Cast Lead Soldiers, Indians, Marines, Trap $15.00, High Voltage B eliminator 5A -74 Street, N. Y. - MUM, High Voltage ABC eliminator Cortland( ners. Animals, 151 kinds. Send 10e for illustrated Cata- $30.00. For details logue. H. C. Sohiereke, 1034 and other bargains write, Irvine's Radio Service. P. O. 72nd St., Brooklyn, N. Y. Itor 07. McGregor, Texas. Chemistry ....,,...... n ...... an.,,u.,...,.,,.m:.,,o.,,muu,..m...... ,.. PMotorcycles Song Poems Learn Chemistry at Home. Dr. T. O'Conor Sloane. noted educator and scientific authority, will teach you. Our Used Motorcycles. Low Terms. Also Parts. Accessories. home study correspondence course fits you to take a position rata lag Free. 1Vestern Motorcycle Co., 946 East 15th St., Song Poem Writers. "Real" proposition. IBbbeleq as chemist. See our full -page ad on page 473 of this Kansas City, Mo. D7X. 2104 N. Keystone, Chicago. issue. Chemical Institute of New York, 16 E. 30th aStreet, New York City. eOld Money Wanted nTelegraphy Courses $2 to paid $500 each for hundreds of Old or Odd Coins. Telegraphy Morse Wireless Keep all old money, it may he eery -Both and taught thoroughly. valuable. Send 10c 11 salaries. wonderful opportunities. Expenses for New illustrated Coin Value kook 4xd. Guaranteed low, Used correspondence school courses sold on renmxnase chance to earn pan. School established fifty years. Cate - basis. prices. Get frosted We pay Cash. Clarke Coin Com- tog free. Dodge's Also rented and exchanged. Money -bock guarantee. rany, 19 Street, LeRoy, N. Y. Institute, Cour St., Valparaiso, Ind.. Catalog free. (Courses bought). Lee Mountain, Pisgah. lAlabama. ,...m ,,,,,,,,,,,,,,,,,,,,,,,,,1...... 1,1,.,,,,,,,.,,,,,.,1.mn.,.,n.,.,,.,,,,.,,,,.,,,,.,,,,,,,,,,,,,,,.,1..1,,11.,,...,,,,,.,, Attorneys Wanted to Buy Detectives Patents -Send drawing or model of your invention for Full Value Paid for Old Gold, Jewelrs, Watches, Dia- examination ;rad instructions. Advice and booklet monds. crowns, bridges, dental gold. silver, platinum, gold free. or silver ore; magneto points, Highest references. Best result s. Promptness assured. old false teeth. Packages re- Detectives Needed Everywhere. Travel. Experience un- Watson E. turned if our offer Is not satisfactory. United States Coleman, Patent Lawyer, 724 9th Street, N.W., Works necessary. Particulars Free. Write, American Detective Washington, D. C. Smelting (The Old Reliable), 39 So. State BL, System, 2190 Broadway. N. Y. Pert. 1G, t'likarm, 111. Patents w ,, ,,,,.,...m,,,..m,,,,,,,,o,,.m,.,,,,,.,,.,m,,.,o,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,w -Send for form "Evidence of Conception" to be signed and witnessed. Form, fee schedule, information free Lancaster and Allscine, Registered Patent Attorneys In Electricity United States and Canada, 269 Corey Bldg.. Washington, .D. C. Electric Fun ! Seventy stunts, 110 volts. $L Cooperce, Patent Sense-Valuable book free. See L :use >'s ad, page Campbell. Calif. ;07. Lacey & Lacey, 631 F. St.. Washington, D. C. Established 1869. This Wholesale Catalog Experimenters! Send dime for impressive 11 r 19 "Danger High Voltage" card. Cary Junes, 519 N. Taylor, Will Save You Money tKirkwood, Mo. Write today for our large illus- ttrated new Catalog "B -1," show- For Inventors Patents-Time counts in applying for patents. Don't ing how this organization of men risk delay in protecting your ideas. Send sketch of model for instructions or write for free book, "How to Obtain with years of experience in Radio a Patent" Inventions Commercialized. Patented or and "Record of invention" form. No charge for can give you personal Unpatented information on how service. Write Adan Fisher Sifg. Co., 278 Enright, St. Louis, Mo. to proceed. Communications strictly confidential. Prompt, careful, efficient senke. Clarence A. O'Brien, Registered Patent Attorney. 309 Security Bank Building (directly across street from Patent Office), If you have a good invention, sorite Hartley, Box 929, Washington, D. C. ]tangor, Maine. AlliedCORP /Radio RATION 711 W. LAKE STREET, CHICAGO Help Wanted Government Positions. Qualify far Raitssay Mall Clerk, Post -Omen Clerk. Carrier, Patents procured at reasonable rates with time to pay. Mural Carrier. and Out door Sales negotiated. posit bras. Steady MA:. Mokune Institute, Dept 730, Staff of registered attorneys and en- Denver. Colo. gineers. A complete secs ice ter ins enters. Wrier for particulars. Inventors Service Bureau, Bog ington, 1048, Wash- Elections have broughtback Custom D. C. Set building, Business is booming. Thousands of old- timers are clean- Help Wanted-Instructions ing up. Let Barawlk show you the, v.ay to bigger profite, more sales. Patents Send today for Barewik's Big Bar- Wanted Immediately, men to qualify for Railway Mail gain Book - the radio mane bible. Clerk, 7'. 0. Clerk -Carrier Tests, $140 Write, -$225 month. Inventions Commercialized- Bascis Oznnent Inst., 251, Ft. Louis, Mo. Patented or unpatented. BARAWII( S. Write Adams Fisher 3f fg. Co., 278 Enright, St. Louie, CO: cácó A. info. Please sat' you sawn it in RADIO NEWS www.americanradiohistory.com Radio IVews for November, 1928 511 Again Tyrman Conquers! The pioneers of the Shielded Grid Circuit now introduce advanced features in a new series of A -C and D -C operated Custom Built Shielded Grid Receivers \t AFEW short months ago, Tyrman engineers deveI- oped and conquered the Shielded Grid Principle in radio circuits. Its introduction was heralded by Set Builders, Engineers and Editors as the greatest advance in radio since broadcasting. Today there is not a receiver using Shielded Grid Tubes which does not bear the ear marks of Tyrman influence. Now after months of systematic experimenting, backed by unsurpassed working knowledge in Shielded Grid circuits, Tyrman Engineers again conquer principles that reach new peaks in Performance, Tonal Qualities, Beauty and Value in Custom Built Receivers. Send for free descriptive literature. When you examine the dia- grams and layouts you will quickly see why, in the Tyrman Series, you can be assured of hairline selectivity, full, rich tonal quality, unequaled power and distance under most trying conditions. (Tyrina n Imperial 8C) Custom -Bilt Shielded Grid For Complete A -C Socket Operation Using A -C Shielded Grid Tubes Designed for those who want to build only the Short the Wave finest in A-C Socket Operated Receivers. Note Coils compact factory-like appearance of the chassis. Tyrman ingenuity in design places the Power UX250 Supply with other apparatus on a cadmium plated Ampli- only 13 in. x 20 34.in. Shielded tying subpanel platform / Tube parts beautifully finished in black crystal. Power Supply designed solely for the "80" and factory Phono- assembled. No adjustments. graph The actual performance of the "80" is defined by a clear 10 '4141.111.1111.191111111,1111111, 111.1 Switch K. C. separation over entire broadcast wave band. Tonal quality of tremendous volume without distortion. DX recep- tion like local without oscillation. Duo Amplification System, a new Tyrman development in the final combination with other features creates unequaled Sensitivity. Selectivity. Stability and Power. Panel only 8 in. x 21 in. of Genuine Butt- Walnut on metal (Pat'd). New crjrm(/ \\72" 110 A -C Tyrman Worm Drive Illuminated Drum. Only three controls with Custom-Bill Shielded Grid and Phonograph Switch on front panel. Simple and quick to assemble. Receiver Parts. factory .packed $134.80. "80" Power Supply $65.00. A -C Socket Operation Complete Parts for Imperial "80 ". short wave plug-in .11. For Battery or coils and Power Supply, ready to assemble. 099 5. only The Tyrman "72" can be assembled for battery, eliminator or Com- plete A -C Socket operation. Even if assembled as a battery set it is a simple matter to convert to complete socket operation. When assembled for A -C Socket Operation uses A-C Power Supply especially designed for the "72" mounted on subpanel platform. The Tyrman Duo System of Amplification,and Tyrman Audio Coupler System assure rich tonal qualities. Sensitivity. Stability, Selectivity, Power and Distance comparable only to the Imperial "80". Front Panel only 8 in x 21 in. of beautiful burl -walnut finish on metal. Tyrman Illuminated Worm Drive Double Drum. 110 A -C Switch and Phonograph pick -up Jack on panel. Easily and quickly assembled. Complete parts for either battery or A -C operation. factory packed, ready to assemble ^CO The "72" Power Supply for A -C Socket operation. factory assembled, $9 $55.00. Complete set plug-in coils $10. Send for FREE literature describing this remarkable (Trinan"6fY New Series of Receivers Custom-Bilt Shielded Grid r For Battery or Eliminator Operation Tyrman Electric Corporation (' Without obligation send me free Dept. 218, 314 W. Superior St. literature describing Tyrman For appearance, tone quality, distance, selectivity, sensitivity, Chicago, Illinois. Custom Built Receivers. stability and power, the Tyrman "60" is comparable only to other Tyrman Shielded Grid Receivers. An improved design for I am particularly interested in "80" A -C Opera- battery or eliminator operation. Especially designed for Shielded Grid Tubes. tion "72" A -C or Battery operation "60" Every part made of finest materials, carefully tested and matched. The Tyrman "60" creates a new standard of comparison for performance and value in six Battery Operation. tube receivers.Panel only 7 i n. x 18 in. equipped with Tyrman st C Single Vernier Drum Dial. Complete parts, factory packed. /- 50 NAME ready to assemble, only VVV Tyrman Electric Corporation ADDRES Dept. 218, 314 WEST SUPERIOR STREET CHICAGO, ILLINOIS Dtv JOBBElt- - Please say you saw it in RADIO NEWS www.americanradiohistory.com 512 - Radio News for November, 1928 ,t1 t. m+h 1 : r l Ì .._ l,- , `> ,ji_> ---- {, Lowest Wholesale Prices Allied Radio Corporation is composed of a large corps of trained men who have had years and years of experience in radio. They know how to get Set Builders results. Their great fund of experience is now available for your benefit. Set Builders They know the newest improvements, the up- to-the- minute demands of and experimenters will wel- the trade, and are ready to give come an association here where tremen- you personal, helpful service. dous stocks of practically all of the 50,000 Feet of Radio latest and newest in Radio is here nationally advertised lines are carried at prices that actually defy com- -coupled with an organization trained 5o,000 square feet of floor space petition. to serve. Immediate shipments are as- in a large modern building is de- sured. Silver-Marshall- Hammarlund- voted exclusively to radio. Floor Roberts -Aero -Tyrman and prac- after floor is filled with a tremen- Lowest Wholesale Prices tically all of the latest kits and parts are dous stock of every variety that Tremendous sales volume coupled available. Your orders, large or small, is exceptionally complete in kits, with a rapid turnover to the thou- will be handled with a promptness and parts and sets of every description. sands of radio dealers throughout the dispatch that should prove a revelation Here are found the latest im- country who have come to depend to you in Radio Service. proved designs and styles in radio on Allied Service enables us to go equipment. into the open market and buy for cash -at tremendous savings -and Dealers these savings are passed right on Dealers who line up with Allied Service New A.C. Sets and Kits to you in the way of better mer- will never disappoint their trade on New A.C. sets priced as low as $35.45 chandise and lower prices. deliveries. Our immense stocks in Also a wonderful array of beautiful Sets, Parts, Kits and Accessories en- consoles ranging in price from as low Immediate .Shipments able you to render real service to as $12 up to $zoo. A complete assort- The Allied organization is trained your trade. Immediate shipments in- ment of the famous Silver -Marshall to service. Real team work sure rapid turnover -eliminating the parts and kits-in stock ready for from executives and department necessity of carrying large stocks on your call. Practically all of the managers to stock clerks and hand -and this, along with lowest nationally advertised lines in parts office boys -all animated by a market prices, will prove an ideal and kits are available here for im- desire to serve -to make Allied connection for the live dealer. mediate shipment. New A.C. Sets, service Radio's most dependable Power Dynamic Speakers-all the service. Send for Large, Free, New, Illustrated Catalog "B -1" AIIiedFRadi.o COR PORTI ON Wholesale Radio Distributors 711 West Lake Street Dept. B -1 Chicago, Illinois Please sap r Cl! saw it is RADIO YEWS www.americanradiohistory.com last. ave caught *with i and PROMPT DELIVERIES' NOW ASSURED ON cS.o, &I44E L D G R ATTENTION! SET BUILDERS Our unique business building plan will triple yourCustom Set business this season. Ask your jr ber or check coupor be- low for full particulars. Shield Grid Am puff iier gives tre- mendous gain unquestionably is t ;. otrpowful rreceiver hate produce,. e yeteord;al ;invitation offsetse newalaboratont .'. our large and hear our Whurator, l und to observe p hodand thr precision and rare taken in matehino and test - ing all parts of Chia remark. obis -et.' F.'. H. Scutt Challenges the whole radio SCOTT POWER PACK and AMPLIFIER This fulluehielded unit is eopeciallp designed tosorplo Beur. rent for !Vane, und has world to any test of et econe:tagie lof ing a m.ee tube. Distance-Volume-Select" Am- selectivity with maximum amplification from the wt ge a sameresu s we O. stn rom our a,ora- The Scott Shield Grid Nine and Power lowest to the highest wave lengths. tory models. plifier is a standing challenge to the entire For the small cost of the Scott Shield Grid Nine world of radio to match its superb per- One Spot Reception you can get all that could be desired of radio -the formance. In range it is practically un- very newest, finest developments of the day. Why The Scott Shield Grid Nine is a one spot Su not enjoy World's Record performance when you limited-due to the tremendous amplifica- Stations come in at one point only on the inferior reception? both of which track practically together, can have it at less cost than tion of the Shield Grid long range amplifier The Scott Power Why not have a receiver that provides actual 10 employed. In volume, selectivity, and tonal tuning extremely easy. kilocycle selectivity? Why not listen in on a radio used with receiver, makes it possible that gives you the whole world. Build the Scott purity, it is absolutely unrivaled. It is the immense volume without the alighes Grid Nine and have it. Enjoy the ultimrv, Record This volume is so completely unde Shield successor to a line of famous World's the turning of one knob covers in radio-NOWI Act Today! Receivers -and is to our knowledge the From merest whisper to full aù.' Circuit Diagram most powerful set available today. always with life -like clarity an and Particulars Low Oper Write at once for full Shield Grid Tubes FREE particulars. Let us In Improved New Circuit The Scott Shield Gri economically send you FREE the Scott Circuit Diagram. operated with dry ba Th eight Examine it yourself. See with your own eyes why Perhaps the greatest single factor in increasing the tubes incorporated in t w 29 performance range efficiency of this new Scott receiver is the use of mils. and will give ample age it affords unequaled -limitless - new Shield Grid Tubes, in a new, improved tremendous power matchless tone. Proof will be the home. Where A. C. current is a ial Also- copies of 6,000 and 9.000 mile circuit. This gives many times the amplification new Scott Power Pack and Amp e sent you FREE. obtainable from an ordinary circuit using 201A ninth tube for the second stage of au reception verifications and other astonishing records. today. Do this NOW I tubes, making this receiver more powerful than This is the latest 250 power tube, affor Clip coupon and mail any other existing receiver known to us. mous volume with matchless tone quay CLIP THIS NOW AND MAILS Perfect Matching of Parts SCOTT TRANSFORMER CO. EASY TO BUILD- I 4454 Ravenswood Ave., Chicago, Ill. Gives Enormous Gain I Please send me FREE circuit diagram, records,and To further increase efficiency in the new Scott Results Guaranteed full particulars of the new Scott Shield Grid Nine. receiver. not only are the tubes shielded, but the Although the Scott Shield Grid Nine is orle of the transformers as well. The extreme care taken in most highly perfected sets ever designed, it is an I Check here for proposition matching and testing the transformers is another amazingly simple one to build. Anyone can assemble to professional set builders. reason for the amazing volume obtained from far it in four hours. Both panel and sub -panel are distant stations. All parts throughout are especially drilled to receive each part, and the shielded grid designed and painstakingly matched with precision amplifier unit comes to you fully wired and tested I Name equipment. The special Selectone Two -Gang con- -ready to be connected into the circuit as simply denser, for instance, matches the inductances of as hooking -up a transformer. No adjustments are the antenna and R. F. coils so perfectly that they required of the builder and you can't go wrong on Street line up throughout the scale and afford astonishing the assembly. We positively guarantee that you SCOTT TRANSFORMER C O., 4454 Ravenswood Ave., Chicago,l11. ITown State www.americanradiohistory.com Compare With Costliest Sets! 'LI \JUDI AMY VI II IRAC'D 3'D'DA1YJ EXPENSEEUNLSS DELIGHTED r 9th Anniversary Offer LATEST ALL ELECTRIC ACC= 9P SUPER SHIELDED AC CHASIS $83.75 J"- N [(DNA' MON View of marvelous new. 3 -year guaranteed, lighted 1 -dial control. All Metal Super Shielded AC -9 WTORI'' PRICES chassis (with (pint switch, built -in AC power sec- tion. phonograph pick -up connection and all latest f eat ur, SAVE 50% removed front cabinet. AC tubes and cabinet extra. Wide Selection of L -J Beautiful Cabinets AC or Battery Sets 30 DAYS HOME TRIAL f- 1 TRACE MARK REGISTERED Ricoly designed, gem uine walnut ero solo CATHEDRAL TONED, SUPER SELECTIVE, of finest type. Elea POWERFUL DISTANCE GETTERS tra -dynamic or mag- Celebrating its 9th successful year, hum -free operation, netic power cone, tremendous long air col umn America's big, old, reliable Radio "kick" on distant stations and speaker. Marvelous Corporation springs a genuine razor -edge selectivity -with its value. sensation in high -grade sets. With costly sturdy construction, latest its latest, Super -powered, 1 -dial features, including phonograph Miracos -the pick -up connec- All Electric tion, ease of tun- wholly BIG DISCOUNTS self -con- Exclusive Territory ing, beauty, and tained, hum - economy -a free, AC -8 and to User -Agents on Miraco will A popular walnut Hi- AC -9, using AC BATTERY OR AC make you the Boy Console, with drop- tubes or the new ELECTRIC envy of many leaf desk. Beautiful 8 OUTFITS two -tone finish. Rare -tube models U whose radios bargain! for batteries or Eliminators -you cost 2 to 3 times as much! are guaranteed values and savings AC-8-$71.50 Many thousands of Miracos- Unbeatable value In a 3- unsurpassed in the fine set field. bought after 30 day home corn - y r guarar teed Super, Compare Shielded Metal Chassis a Miraco with highest- parisons -are cutting through (similar to AC -9 shown Beautifully graceful priced radios, for 30 days in your above). Spinet console. genuine locals and getting coast to coast two- tonewaln ut. Chai c home. Surprise and entertain with the tone and power of costly of speakers. Also cornee your friends-get their opinions. sets, their delighted users report. in Electric Phonograph - Unless Radio Combination. 100% delighted, don't buy Miracos are laboratory -built with it! Return everything -the corn- finest parts, and embody 9 years' ptete outfit -at our expense. Your actual experience in constructing decision is final- absolutely! fine sets. Approved by Radio's Also New, More Only exceptionally fine radios, highest authorities. Powerful Battery of the very latest approved type, at Deal rock- bottom prices, could possibly Direct with Big Factory Sets Everything reaches you splendidly packed The newest and latest in back up so liberally unconditional and rigidly battery operated sets, de- A new -type arm -chair tested to insure your instant a guarantee. Send coupon now for enthusiasm. Enjoy the outfit 30 days- signed with same ad- console. Genuine walnut. then vanced used Very pretty. Low Amazing Special Factory Offer! decide. Liberal 3 -year guarantee on electric sets! Same vide priced. each set. Play safe. save lots of money, choice of cabinets. High- Electro-Dynamic or Mag- and insure est netic-Power Speakers. Don't Confuse with Cheap Radios satisfaction by dealing direct mtality,amazinglylow with Radio's old, reliable builders of fine priced! With its rich, clear Cathedral tone, sets -9th successful year. 8-tube Battery At right, a Lo- IMPORTANT NOTICE! Boy console, Super Shielded "-30 Day Free Trial" offers usually are money -back guarantees frequently only on the "set." walnut finish. Plea, understand that unless yr, arere thoroughly pleased we pay return charges and refund Cassis t hat costslittle. the FULL purchase price on both the "set" and ALL equipment -tubes, cabinet. speaker, $49,88 A gem! antenna (also on batteries or eliminators mill, ultra -8 sets). Could any Tubes, batteries or elim- ger be fairer? inators and cabinets are extra. 30 days home trial MIDWEST RADIO CORP'N,404 -AN Miraco Bldg., Cincinnati, Ohio on EVERYTHING' Above, popular inexpensive BEAUTIFULLY ILLUSTRATED CATALOG, AMAZING combination. Set on Table SPECIAL FACTORY OFFER, TESTIMONY OF NEARBY USERS-All tie proof you want Speaker (sold separately). ite -of our honesty. fairness, sire, financial intezrity.radio pea lgríWrI _ experience and the performance of our sets- including Amazing Factory Offer -sent with catalog. Metal or wood compact style cabinets. Wood cabinets in walnut or ofMIDWEST RADIO CORPORATION new shaded silver- THIS COUPON Pioneer- Builders of Sets -9th Successful Year IS NOT chrome finishes. Cathe- t ddral Electro- Dynamic 404 -AN Miraco Bldg., Cincinnati, Ohio AN ORDER \l agnctie -Pow er WITHOUT OBLIGATION. send free catalog. Speaker to match! Amazing Special Factory Offer, testimony of nearby users, etc. User O Agent Dealer Check here if Interested In an EXCLUSIVE TERRITORY PROPOSITION u NAME ADDRESS www.americanradiohistory.com