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www.americanradiohistory.com Radio News for Januart, 1929 609
Send Coupon Below for FREE Radio Idea Book
REDUCE STATIC BY MARVELOUS. NEW METHOD asy Ways to Make 39-9 an hour in Your ¡pare /ime in RADIO Each of these plans, developed by the Radio Association of America, is a big money- maker. Set owners everywhere want to get rid of static, to have their sets operate from the electric light socket, the tone improved, and the volume increased, and trans- formed into single -dial controls. Phonograph owners want their machines electrified and radiofiéd. If you learn to render these ser- vices, you can easily make $3.00 an hour for your spare time, to Earned Over $500.00 say nothing of the money you can make installing, servicing, repair- In His Spare Time ing, building radio sets, and selling supplies. Frank J. Deutsch, Penn.: "I bare made over $500 out of Radio in Over $600,000,000 is being spent yearly for sets, supplies, service. You my spare lime. Yours is a great can get your share of this business and, at the same time, fit your- plan for ambitious men." self for the big -pay opportunities in Radio by joining the Association. A Radio Engineer In One Year Claude DeGrares, Canada: "I Join the Radio Association knew nothing about Radio tchen .1 joined the Association a year ago. I am now a member of the of America engineering staff of the DeForest A membership in the Association offers bigger pay for you. A membership need Company and my income is 225% you the easiest way into Radio. It will not cost you a cent! greater (han at the time I joined. enable you to earn $3.00 an hour up- The Association will give you a com- wards in your spare time -train you to prehensive, practical, and theoretical Doubles Income install, repair and build all kinds training and the benefit of its Employ- In 6 Months of sets ment Service. -start you in business without capital You earn while you learn. W. E. Thon, Chicago: "You have Our cooperative plan will make it possi- an excellent plan. Six months or finance an invention- train you for ble for you to establish a radio store. the $3,000 to $10,000 big -pay radio posi- after I enrolled I secured the You have the privilege of buying radio managership of large Radio store tions - help secure a better position at supplies at wholesale from the very first. and doubled my income."
ACT NOW -If You Wish the Radio Association of America Dept RN -I 9513 Ravenswood Ave., Chicago, III. No -Cost Membership Plan Gentlemen: Please send me by return mail full details of your Special Membership Plan, and also copy of To a limited number of ambitious men, we will give Special Member- your Radio Idea Book. ships that may not - need not -cost you a cent. To secure one, write today. We will send you details and also our book filled with dollars- and -cents radio ideas. It will open your eyes to the money -making possibilities of Radio. Name.
Radio Association of America Address 4513 Ravenswood Ave., Dept. RN -1 Chicago, III. City ____ State
P 1, cr su ç ;; it .in RADIO NEIi-S
www.americanradiohistory.com 610 Radio News for January, 1929 \\ 'ANE WS Volume 10 January, 1928 Number 7
HUGO GERNSBACK, Editor -in -Chief ROBERT HERTZBERG, Managing Editor C. P. MASON, Associate Editor BERYL B. BRYANT, Laboratory Director C. WALTER PALMER, Director Information Service
Contents of This Issue
"Mysteries" of Radio ,P For the Beginner-The "Blonpless" One - By Hugo Gernsback 619 Dial, Two -Tube Receiver 642 Human Radio Reflectors, or Everyone Some Hints on the "Junk -Box" Receiver 646 His Own Aerial A. Binneweg, Jr. 620 -By The "Lamp- Socket Five" -A Simple A.C. Automatic Receiver "Listens" for "SOS" Set - By Beryl B. Bryant 647 (Pictorial) 622 End of Monthly Constructional Prize Radio Does Not Change the Weather 6M By B. Francis Dashiell 623 Contest What's New in Radio 626 Radio Wrinkles 652 Television -The Latest Developments in On the Short Waves 654 the Field By Robert Hertzberg 630 New List of Broadcast Station Calls 656 High Frequencies for Color Television RADIO NEWS Laboratories 658 C. Gleason 632 By Sterling The Radio Constructor's Own Page Giving Television the "Last Touches" By Himself 660 By C. P. Mason 634 I Want to Know By C. W. Palmer 661 637 New Television Systems (Pictorial) Tubes in a Class with the Pullman Cars 668 Some "Foolish" Questions and Their An- swers By H. M. Bayer 638 Review of Recent Radio Literature The Dark Side of Radio By H. M. Bayer 689 13y Dorothy Gernsback 641 qF RADIO NEWS Free Blueprint Coupon 701
In Our Next Number THE A.C. SCREEN -GRID PERIDYNE: The latest titis unit will furnish signals strong enough to fill and most advanced model of a set well -known to a theatre and clear enough to satisfy the most our readers. An all- electric, completely -shielded critical music lover. Uses a 250 -type power tube - broadcast receiver, self- contained in a metal cabi- the largest receiving tube made. Another Free net. High sensitivity, selectivity and superb Blueprint article. tone quality are its features. A fine set for the custom radio builder. Free Blueprints of this set Blueprint Notice will be available. Readers desiring free blueprints ui 'the sets de- A HEAVY -DUTY AMPLIFIER AND POWER scribed in this issue must use the coupon on Page 701. PACK: Attached to the detector tube of any set, No blueprints will be sent without it.
RADIO NEWS is published on the 10th of each preceding month. Than are 12 obtained from the publishers. Copyrighted in Germany. Reproduction of articles numbers per year. Subscription price is $2.50 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 Brentano's, Are. de L'Oeera, Paris, France. European agente: S. J. Wise money orden should be drawn to order of EXPERIMENTER 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 Turk. Mention the Editor, RADIO NEWS, 230 Fifth Ave., New York. N. Y. Unaccepted contribu- name of the magazine you are ordering. We also publish SCIENCE AND INVEN- lions 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 $2.50 per ments; good photographs accompanying them are highly desirable. Publishers are year. money rifer, or re. Sob - not responsible for loss of manuscripts, although every precaution is taken with etter if ca hmis eenclos d. Avoidlseinding cash hthrough' the possible. Sub- such manuscripts, upon receipt thereof. scriptions for less than one year are not accepted. Subscription may GUI in RADIO NEWS. Monthly. Entered as second -class matter, July 12, 1924. at the combination with SCIENCE & I \TEilTION, RADIO LISTENERS' GUIDE. Post Office at New York. N. Y.. under the Act of March 3, 1879. Additional entry and AMAZING eTORIES. at Dunellen, N. J. and San Francisco, Calif. Title registered U. S. Patent Office, POSTAGE. We postage in all parts tpt L' States, 50e:ico and Copyright. 1928, by The Experimenter Publishing Co., Inc., 230 Fifth Ave., island potoeahens. Forscri foreign or Canadian subscriptions e require 50 cents in New York. The contents of this magazine are copyrighted and must not be addition to the price for sas tari postage charge. reproduced in the United States without giving full credit to the publication. CHANGE OF ADDRESS.ADDe anS. dress age far ou advance ac It tc0ulrys Translation into foreign languages must not be made unless permission is several weeks to make an address change on our recarda. Always write clearly. The contents of RADIO NEWS are indexed in the Industrial Arts Index. copies of which can be found in every library.
Published by Experimenter Publishing Company, Inc. H. GERNSBACK, President S. GERNSBACK, Vice -President and Treasurer IRVING S. MANHEIMER, 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 Radio Neu'.c for January, 19'(' 611
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www.americanradiohistory.com 612 Radio News for January, 1929
INDEX TO ADVERTISERS
A F P Fansteel Products Inc. 677 Per -Con Manufacturing Company 677 AcoustiCone Labs. ., 677 Ferbend Electric Co. 677 Pilot Electric Mfg. Company Back Cover Aerial Insulator Co. 677 Ferranti, Inc. 700 Pohl Bros. 689 Aero Products Inc. 678 Freshman Co., Inc., Chas. 694 Polk, J. L. 681 Aerovox Wireless Corp. 701 Fritts, H. D. 677 Potter Company, The 678 Allied Radio Corporation 670-678-680-683-704 Premier Electric Co. 687 American Radio & Merc. Co. 684 G Press Guild, Inc., The (74 American Sales Company 676 General Radio Company 674 American Transformer Co. 679 H R Arcturus Radio Corp. 690 Radial! Company ' 690 Hammarlund Mfg. Co. 685 Radiart 677 Hammarlund- Roberts, Inc. 618 Labs. 690 Radio Association of America 609 B Hoodwin Co., Chas...... Radio Doctors, Inc. 685 03arawick Co., The 670-677-680-684-687-689-690 Hotel McAlpin 674 Radio Equipment Company 694 694 -695- 697 -698 -700. 702.703 I Radio Institute of America 613 -671 Birnbach Radio Company 677 Illinois Transformer Co. 684 Radio Producer Company 680 Bodine Electric Company 677 Independent Electric Works 684 Radio Specialty Company 669 Braun, W. C. 677 Insuline Corp. of America 677 Rawner Radio Company -- 677 Browning-Drake Corp. 694 Raytheon Mfg. Co. 697 Royal Electric Supply C. 683 J -M -P Manufacturing Co.. Inc. 701 Eastern C S 703 X Carborundum Co., The Karas Electric Co. 674-693-703 Samson Electric Company 677 Carter Radio Co. 684 Kelsey Company 694 Scott Transformer Company 678 CeCo Mfg. Co., Inc. 670 680 See Jay Battery Company 690 690 Kilo Radio Company Central Radio Labs. Knapp Electric Company Shanklin Mfg. Company 693 Chemical Institute of N. Y. Inc. 672 668- 673.684. 694.697. 698.700 Silver -Marshall, Inc. 614 Chicago Radio Apparatus 698 Smith, B. Hawley 680 Chicago Salvage Stock Store 615 L Stock Gear Works 691 678 T Chicago Lacey & Lacey 699 Clark & Tilson, Inc. 612.690 -698 Lee House 694 Teleplex Company Clarostat Manufacturing Co. 698 Lentz Inc., C. R. 693 Televocal Corporation 694 Coats, Fred. R. 670 Lincoln Radio Corp. 697 Terlec Radio Mfg. & Sales Co. Consrad Co., Inc., The 676 Littelfuse Laboratories 697 Inside Front Cover Cornish Wire Co. ...._....- .... - ...... 677 Lund Mfg. Company, I. A. 677 Thordarson Electric Manufacturing Co. Coyne Electrical School 611 Inside Back Cover Craftsman Radio Products 691 Mc Townsend Laboratories 687 Cunningham, Inc., E. T. 668 McSweeny Electrical School 691.699 Transformer Corporation of America 670 Twin Company 677 M Coupler D Tyrman Electric Corporation 675 M. & H. Sporting Goods Co. 681 DeForest Radio Co., The 698 Mertz Specialty Company 677 II DeJur -Amsco Corp. 677 Mason, Fenwick & Lawrence 701 Underground Aerial Systems 617 Dresner Radio Mfg. Co. 678 Midwest Radio Corporation 665 Dubilier Condenser Corp. 699 W N Walker Co., The Geo. W. 666 E National Company, Inc. 689 Western Radio Manufacturing Co. 677 -699 National Radio Institute 616.617 Wholesale Radio Service Company 684 Electrad, Inc. 681 -695 National School of Visual Education 664 Electric Specialty Co. 703 New England Mills Company 698 x-Y -Z Elkon, Inc. 663 Newark Electric Company 677 X -L Radio Laboratories ...... - ...... - .... « 668 Excello Products Corp. 668 Norden- Hauck, Inc. 683.691 Yaxley Manufacturing Company 695 $150 SM Reception at a $50 TO the thousands of fans for whom the four - it harmonizes beautifully with any home - tube, R. F. amplifier, regenerative detector furnishings. and two-stage audio amplifier is the time- tested Price Despite this demonstrated superiority, in standard of receiver comparison, the new Silver - every respect, over all other sets in its price Marshall Coast-to-Coast Four offers the finest class against which we have tested the 740, performance yet attained with this re E arkable the complete kit of all approved parts costs circuit. A screen grid R. F. amplifier stage, immeasurably finer but $51.00 or the 740AC kit, $53.00 complete. The 700 cabinet coils than ever before, the new Clough high -gain audio system, is $9.25 additional, or is included with 740 wired, $75.00; and and an all -metal assembly like those of the finest of ready -made 740AC wired, $78.00. sets, make the "740" the biggest $51.00 worth of radio set you've ever listened to. We go emphatically on record that no matter what set you build The Coast- to-Coast Four, at Chicago, plays on the speaker or buy, the 740 Coast -to-Coast Four is the best dollar for dollar New York, Florida, Texas, and California stations, cutting through value you can find around fifty dollars. It goes together easily and local Chicago interference only 10 or 20 kc. away. Its tone quality simply, performs with a vengeance, and for the professional set - is such as only S-M transformers can provide. Housed, like the builder provides a low-priced set that will out -demonstrate ready - 720 six, in the new S-M 700 table -model metal shielding cabinet, made sets at twice its price. P CLARK & TILSON S -M Parts Always in Stock 22 Chambers St., New York, N _Y. We always have a large stock of S -M kits and parts, as well Please mail your catalog showing S-M parts and kits, as other high -quality apparatus. Send the coupon for our and other high -quality radio apparatus, as advertised catalog. Discounts to dealers. Try us for quick service. in January Radio News. Name CLARK TILSON Address 8 City State 122 Chambers Street New York, N. Y. iss. ss mimm m s.mmJ Please sal yot saw it in RADIO NEWS www.americanradiohistory.com Radio News for January, 1929 613
"How I Laughed Myself Into Success in Radio" by Howard Clark,
etI'm sitting on top of the during my spare time. I actually world! My bank account learned by doing. With the les- sons I received a complete, expen- is growing fatter every day sive storehouse of apparatus with . . my home is all paid which I was able to build radio for ... I've just ordered a circuits and sets of almost every new car ... and my wife description. Yet it cost me ab- and I can at last enjoy life solutely nothing extra. in real style. feels As a result of this practical, tech- It sure nical working out of big radio great to be earning big problems with a fine home - money. And to think how laboratory, I was able to earn it all came about!" good money even before I had completed my course! And it wasn't long before I was able to IT happened on a rainy Mon- quit my regular work entirely... day night. I was reading a and branch out for myself in magazine while Mary was clear- big paying radio jobs. ing away the supper dishes. Sud- Today, I have more work than denly a funny cartoon caught my I can take care of. And I often eye ... and I laughed out loud. make more money in a day than "Jim, you make me sick!" she I used to earn in a week. cried. "How can you laugh while I'm nearly dying of weariness!" Read this thrilling Free Book "But Mary dear -" Howard Clark's story is typical "Don't dear me, you idiot!" of the success which scores of I was alarmed. "Great heavens, what's other men have achieved . .. through wrong ?" the "big- league" training given by the home -study course of the Radio "Wrong? " she screamed,"here Idrudge Institute of America ... the only school all day, do my own housework, wash in America sponsored by RCA, General all the clothes, take care of the baby, fact that success was practically assured by means of a new home -study lab- Electric and Westinghouse. and worry about your meals. I never Radio needs you. Manufacturers, get a moment of freedom and oratory method sponsored by three of ... America's great corporations. dealers, broadcasting stations, ships haven't a decent thing to wear even to radio church yet you never seem to care!" all need trained experts. ... Wich gigantic enterprises like these The pay is big. The opportunities are I was ashamed! behind a school I needed no greater limitless ... The work is thrilling! guarantee .... so without a second's Find out all about it. The Institute A feeling of shame swept over me. So further hesitation I tore the coupon has prepared an interesting, illustrated that was why she seemed so "moody" and mailed it. booklet telling you all you want to the last few days! Like a good sport A lucky event that changed know about this vast industry and she had suffered in silence until she about the remarkable home -study couldn't keep it in any longer. Poor kid! my life course that can fit you for a brilliant For hours after Mary had gone to bed It sure was my lucky day, when the radio career. Just mail the coupon be- that night I kept staring into space. first lessons came in. I never dreamed low ... the booklet is abso- What a mess I had made of our lives that learning radio was so easy. I didn't lutely free. Radio Institute .. What a slave I had made of her. know the first thing about it when I of America, 326 Broad- Listlessly I kept thumbing the pages of started. Yet before many months were way, New York. the magazine thinking think- over I was able to solve many of the ...... problems which command big pay. ing. Was there no way out of it? Mail this Each subject was explained in Then suddenly ... as if by some kind simple coupon act of Providence .... I stopped be- word and picture form. It carried me fore a story. It told of a fellow who along like a novel. From magnetism and electricity the lessons took me step by had made quite a fortune in an un- Radio Institute of America crowded profession. Fascinated, I read step through trouble- finding and repair- Dept.R1L1,326 Broadway, New York ing- through ship and shore and broad- on. It told of the brilliant opportu- Gentlemen: Please send me your big FREE nities in the radio industry ... of the casting apparatus operation and con- 50 -page book which tells about the great oppor- big incomes fellows like myself were struction- through photoradiograms, tunities in Radio and about your famous labo- ratory-method earning ... and of the ease with which television and beam transmission. of radio instruction at home. expert radio training could be acquired. I didn't have to give up my regular job. Name But what impressed me most was the I stayed right at home and learned Address
Please sal, volt saw it in RADIO NEWS www.americanradiohistory.com 614 Radio News for January, 1929
Volume to Fill Any House the Last Word in Realism
Or from Any Phonograph Radio with this -4- Listen -In and on London this with the y Round -the- World four
NOT with any ordinary radio receiver, of course -the Atlantic is too wide for regular broadcast receivers to bring you London pro- The new 2 -stage S-M 678PD Phonograph Amplifier is grams. But turn on your S-M "Round -the- priced so low that, while particularly adapted for dance halls World" set some night. Don't be surprised if the and small theaters, it is ideal for the home also. Used with language you hear is a foreign one, or if the any 110 volt D.C. dynamic speaker, it takes input from any announcer mentions "Paris" or "Amsterdam," magnetic phonograph pickup, or from the detector tube of a or "London" instead of the cities you are ac- broadcast or short-wave receiver, and, by means of its S -M customed to hear from. Call your neighbors to Clough- system audio transformers, supplies to the speaker listen if you want to-but be cautious about call- undistorted the full power output of its 250 -type tube. All ing anyone who has already explored the mys- input power is taken from the 110 volt A.C. house -lighting terious short-wave channels with an S-M set- mains. Price, wired, $73.00; complete kit, $69.00. your wonders might sound very tame to him. Or you can get 250 -tube power right in your present set by Perhaps by this time he is only interested in inserting a 250 tube (with an adapter) in the last socket of New Zealand and Japan! For in short-waves al- the set, and using the S-M 675ABC Power Supply-which most anything is possible; amazing feats of distant furnishes ABC power for the 250, and B power to the entire reception are becoming a matter of common set (or full ABC power to A.C. tube sets). Price, 675ABC kit, knowledge. (See prices on opposite page). $54.00, or factory- wired, $58.00. True Tone Quality from New S -M Audios
Are you receiving "The Radio- S-M Clough -system audio transformers builder" regularly? No. 6 tells all are guaranteed unconditionally to give about the new S-M Public Ad- better tone quality than others, with tB.6i fIawuu w.siausu dress Amplifier. No. 7 describes higher amplification, regardless of size, =mum ...IIMO1 two interesting short-wave devel- M1111111411 opments, and a new S-M 750 volt weight, or price. They sell in tremendous im11111111im11H " r power supply. To all Authorized quantities, by simply comparing results t!t1g1111gDemmumimassall111s15111 S-M Service Stations, it comes free !1 of charge; to others a nominal with others in the comparison amplifiers s11iÍ1/11Ì1Ì:::9:._e4_s:..ï charge is made. Use this coupon. used in S -M demonstrations at recent radio shows. 1111111 WIp111rS4. Ma N11 11111 11Ö111111 t7111 M MIN...0II.1^I If you build professionally, Cmziÿ,.Il7yá C 1 Ca::::::::: imCg111gU write us about the Service Station In the curves at the right E is the two-stage e__ai .' niii i iá=i éiinauus a__a iiiiiiiui franchises. Or if you don't build, curve for the large -size transformers (S-M 225. IIMI IM MI M L211..111 1=1 1M aI...I1...I1 MM.11M.11 yet want your radio to be custom - 1st stage; and 226, 2nd stage, $9.00 each). D is IM i mN 1111 11 1111 111 i m11 1111 1111 S i m111 1111 1.11 made, S-M will gladly refer our that of the smaller ones (S-M 255 and 256, $6.00 IIIg1111g1111IMIg1111gI111ggllllgglll inquiry to an Authorized Silver - each). Note the marked advantage over A, B, 1 Marshall Service Station near you. and C standard eight and ten dollar trans- iiiilllilUlliiiliiiiiliiiliiiili -all `tmada ina me am formers under equal conditions. hammy
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Please say you saw it in RADIO YEiVS www.americanradiohistory.com Radio News for January, 1929 617
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Vol. 10 JANUARY, 1929 No. 7 " mysteries" of Radio By HUGO GERNSBACK
IHAVE often made the assertion that very little is actually - Then, of course, there is another well -known type of unexpected known about radio today; and, while we know some of the happening, which, however, is not so puzzling as those previously instrumentalities that make radio possible, a good -sized library cited; and that is, when your receiving set becomes a broadcast could be filled with volumes on the various aspects of radio station. It has more than once happened in the past that, while about which we know little or nothing as yet. Every once in a a radio set was turned on, people several miles away were able while, we hear about some new radio "mystery" that leaves our to listen in with their own radio sets to the conversation going scientists up in the air. Immediately, a good many theories are on in the room in which this particular radio set was located. propounded as to the how and why of such phenomena; but, in A great deal of wonderment has been caused by this sort of the end, we are about as wise as we were before. thing, but it is really no great mystery at all. Some radio sets, The press very frequently reports some of these mysterious oc- as a matter of fact, are transmitters, as perhaps most people currences, and many ofthem seem to be well authenticated. For already know. If the set is in an oscillating condition and has a instance, not so long ago, there was a report from Boston that loud speaker connected to it, under certain circumstances this a water faucet had started, for no apparent reason, to give out loud speaker will become a microphone; and anything spoken in radio music from a radio station about a mile and a half distant. the room will be put "on the air" by this particular set. If a How the faucet can do this, no one knows; various theóies have neighbor one or two blocks away has his radio turned on and is been propounded, but none seem to be fully satisfying. In fishing for a station, he will sooner or later come across the wave order to receive radio waves, and make them audible, we must emitted by the oscillating receiver down the street. He will hear first "detect" them electrically and then transform the electrical voices, perhaps familiar ones, and may pick up a lot of gossip impulses into sound. As a detector we usually use an imperfect - that was not meant for his ears. contact or crystal -type rectifier, or a vacuum tube, and for the Of course, a thing of this kind is usually done unconsciously and, sound -producing medium a loud speaker. A more or less com- as a rule, a great to-do is made when it happens. The newspapers plicated array of instruments is required to reproduce radio begin to feature the existence of a "secret broadcaster" and, if the music clearly in a fair -sized room; but in the Boston case, evi- condition persists, it is even carried to the Radio Commission at dently, there were no such technical instrumentalities. Evidently 'Washington. The "mystery" is not a msytery, and there is no Mother Nature, through a happy train of circumstances, took secret broadcaster; but a set owner who might better be called an charge and produced the mystifying results. Just what was the innocent or ignorant broadcaster. detector and what the amplifier, no one seems to know. Of course, such an involuntary broadcast will not happen every time you talk in front of your set; there must be a long train of This odd occurrence, however, does one thing; and that is to not happen. radio engineer abundant food for thought, and prove fortuitous circumstances making it possible, or it will give the incidentally, when it does happen, you are violating the Federal to him conclusively that there is a good deal to learn about radio, And from now Radio Law, and you are liable to get into trouble with the authori- not vet contained in any text book. Perhaps ten yens particular "mystery," which might we will be using such simplified radio sets; and, while we may ties. So the remedy for this is not to allow your set to oscillate. not use a faucet with running water as our loud speaker, better be termed a "nuisance," possibly of is no we may take advantage of similar principles. In the Boston case, Then there is a "mystery" another sort, where there me right, the music stopped when the offending radio set, yet your loud speaker suddenly blurts forth if my memory serves on by water was turned off. a complete telephone conversation, as it is being carried a number of neighbors. The latest gossip from the town begins A similar radio mystery was encountered in London, when a to sizzle over your speaker, hot and heavy, and you do not miss lamp post in one of the busiest thoroughfares started to give out a single luscious bit of information. All this goes on, incidentally, radio music, including announcements of the local station, whose without the two gossipers on the party line being aware that any sounds were reproduced. 'Whether the arc lamp contained in the one is eavesdropping. Indeed, there is seemingly no electrical lamp post was the detector in this case, or whether the switching connection; yet the dialogue with all its poignant results is coming arrangement inside acted as an amplifier, no one seems to know. out of the loud speaker, loud and clear. Which is a pity; because, here again, there seems to be another This, too, is not a deep mystery and, fortunately, it is rare. It radio principle involved, which calls for a theory entirely different happens usually when one line of the telephone circuit becomes from that of the water- faucet phenomenon. grounded, and we get the phenomenon of so- called "rising cur- Similar mysterious occurrences happen from time to time, and rents." This used to be the nightmare of telephone engineers when they are usually well authenticated; but it would seem that none the telephone was younger, and when the ground was used uni- of the different occurrences can be brought under any regular versally for the return. In these days, where practically every classification as far as the method of operation is concerned, or telephone line has two solid copper wires, the phenomenon is some- only roughly so. This again proves how little we actually know what rarer; but, very often, a phone or line becomes grounded and, about radio. if the circumstances are right and the distance is not too' great, the Some years ago, when the design of audio transformers had above- described results follow. Very often, however, the cause not reached its present perfection, you could often hear radio may be simply the inductive effect between a telephone line and music from your set without loud speaker or telephone receivers. an aerial running parallel to each other for some distance; or it In other words, the whole set apparently became a musical may be a combination of this with a common ground that does instrument. the trick. If you were required to duplicate the results somewhere In this case, the mystery was not quite so deep, because here else, it would probably take a lot of engineering and a great deal the music can be traced immediately to its source; it has been of apparatus to do so. The conditions must be just so, otherwise shown that an audio transformer, unless the laminations of its iron no "results" appear. core are quite tightly packed, will emit sounds corresponding to These are only a few of the better -known radio "mysteries." If the currents passing through it. Perhaps this will give someone our readers know of any others, we should be glad to hear the a good idea of a way to build a new type of loud speaker; which details from you; and if they are authenticated, RADIO NEws will may or may not be more efficient than those we have today. be glad to publish them.
Mr. Hugo Gernsback speaks every Tuesday at 9.30 P. M. from Stations WRNY (297 meters) and W2%AL (30.91 meters) on various radio and scientific subjects. 619
www.americanradiohistory.com 620 Radio News for January, 1929
Each individual who steps into the line increases the strength of which, as a matter of fact, could be put ninch farther away. Each the signal received on the receiving aerial alongside of the indicator, individual is a re- radiating aerial for the ultra-short waves.
Human Radio Reflectors, or Everyone His Own Aerial Interesting Tests Give Remarkable Results on Short -Wave Transmissions
By A. Binneweg, Jr.
at the University of Cali - have served as a radio reflector to direct any of the apparatus used, if it is placed fornia have discovered that the human transmission in the opposite direction. behind a screen. At certain definite frac- STUDENTSbody acts as an efficient radio re- The effect is a mysterious one, since the tions of a wavelength from the antenna, the flector. In actual tests, the approach spectators cannot see what takes place. One presence of a body causes the horn to sound of a human body toward a wire, suspended walks up to such a system of wires and and, if the adjustments arc sufficiently sensi- in space, lias been made to actuate a pow- hears the horn sound but cannot in any tive, the device will operate while the ap- erful electric horn. Several persons stand - way feel the presence of the radio waves proaching person is still at a considerable i ig., around a three -meter transmitting aerial actually reflected from the body, nor sec distance from the transmitting equipment. The experiment is an extremely novel one and, when performed before a group of vis- itors, always proves of exceptional interest. CORD WALL /// It is well known that radio waves may be directed in a given direction by suitably aINSULATORS->t9 arranging a system of wires around the ' t ' i Ij ï';TRANSMITTING AERIAL c transmitting aerial. At a wavelength of 3-METER RECEIVER 1.11 i; l i ii; ii 1 1 I about three meters it has been found that 1 1 I u 1 i I Hill, 'I í I I_ ulIn i I¡ i these wires can be replaced by human bodies }i,,j l l 1111 11111 I Ét' WALL} and the saine effect will result. Some per- '` I1000pLY ¡iiii;¡ili1i 1 i sons are better "reflectors" than others, -,\ N 111I1ii¡114iiiWI1 I 1 when a definite wavelength is used; and
1 Ì 1 Ì 11I¡1111111h~u111 each person has his own "natural frequency" R.ECHOKES 1 1111íñn I 1 1I 1 1 . 4i at which reflection will be a maximum. In 3-METER the future, who knows but that the police ii i I I I / 1'1I I I I'ii¡iii TRANSMITTER I may classify criminals, not by their finger- RELAY I '1RE'¡ 111 I ¡Iomits! i j1I i¡ prints alone (although perhaps these will
1 1 1 I RIAj1i I I also be used), but by their "natural frequen- 1 11111i , 1111111 1 1 I I , 1 1 1 1 11 1ll cies"? -/v As the human body grows, its i1' natural fre- 1í1' quency decreases in value and thus a grow- -AUTO HORN I E1i -METER- ing person "tunes" his body over a definite 4 wavelength range. A baby has a much j higher natural frequency (perhaps this ex- FIG. I plains the reason of those high- pitched "squeals ") for given conditions, than an In this case, a blank wall ',fleets (11e short waves and, at the right distance, will adult. This fact may prove of considerable send them bock in phase with the transmission. The thermocouple in the resonant value to the medical profession, as will be aerial then generates a current amplified through the receiver. explained later.
www.americanradiohistory.com Radio News for January, 1929 621
give rise to a directional effect. The human body can replace such wires, when the trans- DIRECTION OF TRANSMISSION mitter operates at about three meters, and a actual tests with reflectors have shown that i the human body acts as an efficient reflector i of radio waves. In these tests, a vertical and a low -power vacuum - transmitting aerial TRANSMITTING tube transmitter were arranged as shown in AERIAL Fig. 1, and a receiving aerial, resonant at about three meters, was hung from a cord, tyWAVE- as shown. At the center of this aerial was LENGTH arranged a thermocouple, so that any re- would actuate the receiver, ceived energy POSITIONS FOR VISITORS SHOWN the plate circuit of which included a delicate BY CROSS -MARKS FIG.2 relay this relay could close or open the circuit connecting a storage battery and The vertical reflectors (inn this case fanned auto horn. It is thus seen that, if the re- by human bodies) when arranged along a para- horn will bola whose focus is the transmitting aerial, ceived energy is sufficient, the form a bean- transmission system, of a sort. blow. This relay was so adjusted that the received energy was just insufficient to blow the horn. It is evident that the least in- fled by the experiment, but it can be re- crease in received energy will actuate the peated, of course, by anyone having the relay and sound the horn. necessary small amount of apparatus. The experiment was found to be a spec - In other tests, a parabola was drawn in tacular one and was accordingly tried out chalk on the floor. A parabola, of course, on one of the "open- house" days of the uni- is the ideal shape for a radio reflector; one versity, when the attendance of visitors is of this kind acts much as an automobile large. The experiment was performed by headlight mirror to ordinary light waves, the advanced students. sending out radio waves in one direction. A large circle was drawn about the wires If vertical wires are placed around a para- to keep all visitors at a distance so the sys- bola, the reflection will be in the direction tem would work properly. One of the stu- shown in Fig. 2. The positions marked "X" dents would explain the device and then an- are those at which, approximately, good di- other would approach the transmitting rectional reflection is obtained and indicate aerial from the rear. At distances from the the relative positions at which the various aerial of one- quarter and three -quarters of visitors were asked to stand during the dem- a wavelength, approximately (but these dis- onstration above described. In this case, tances were not very critical) the horn the relay on the receiver was removed, and would blow. Of course, all the visitors were a galvanometer was connected to the aerial. rather skeptical, and some would look for With the transmitting set in operation, the "hidden button "; lint the operation is the strength of the received signal shown in really simple. the galvanometer will be a definite amount; but, as more and more visitors are requested This picture of a 5 -meter transmitter at the to take the positions marked on the floor, THE APPARATUS General Electric Laboratories, Schenectady, in- ARRANGING as shown by the gal- dicates the length of the aerial (the upright the received strength, rod) required to radiate such a short wave 'l'he body, being resonant at approxi- vanometer, increases greatly. At frequent .successfully. It is about seven feet. mately three meters, absorbs energy and re- intervals the operation of the equipment was radiates it again, thus acting as a trans- explained so that, when the visitors left, mitting aerial sending energy in all direc- there was no reason to wonder what was THE EFFECT EXPLAINED tions and, thereby, effectively as a reflector. coining next. A single vertical wire, suspended above The receiving aerial thus receives signal en- Other interesting effects were noticed. the earth, has inductance and capacity and, ergy which would not otherwise reach it, Different persons have, as has been ex- therefore, a natural frequency depending and the relay which operates the horn is plained, different natural frequencies. Dif- upon these values. The human body has in- actuated. Many of the visitors were mvsti- (Continaed on page 674) ductance and capacity and therefore has also a. natural frequency. At this natural frequency (as in the ease of a wire) it will absorb maximum energy from passing radio waves; that is, it will resonate at that par- ticular frequency. The human body will therefore, like a wire, act as an efficient re- ceiving aerial at some particular frequency. A vertical wire, to operate at its fundamen- tal or natural frequency, is cut at a length approximately one -half that of the wave- length. Therefore, for best operation at a wavelength of three meters, such a wire must have a length of approximately 1/ meters, or about five feet. A short man will have a natural frequency of approximately three meters and a taller one will have a natural frequency corresponding to a wave- length somewhat greater. The human body is in itself a receiving aerial and, under cer- tain conditions, as explained below, can take the place of a transmitting aerial.
TILE REFLECTOR It is well known that certain types of di- rectional- transmission systems make use of tuned wires at definite distances from the This illustration of a five -meter receiver, exhibited at a radio world's fair some radiating antenna to absorb and re- radiate years ado, shows how small are the coils which may be used, and how short the the energy from the transmitter, and thus aerial and counterpoise (left). The device at the right is a wavemeter.
www.americanradiohistory.com Radio News for January, 1929 Automatic Receiver "Listens" for "S O S"
When Radio Shouts the Sea's Call of Distress, This Apparatus Responds Like a Fire Alarm When a Box is "Pulled"
"Sparks," the ship's operator, must sleep at times, and thus relax his watch for the calls of ships in dis- tress. When he lies down, however, he knows that the ringing of the bell above his head will mean an "SOS," and that it will then be up to him to do his bit in keeping up the record which the radio men of the sea have made in the /tours of emergencies. Another bell is ringing in his transmitting room, and a third on the bridge, informing the officer on duty that he mist expect startling news. It may be explained, however, that this signal is not the "SOS" (. - - -...) itself, but a pre- liminary to the announcement giving the name and position of the ship in distress. The photograph was posed by Operator F. R. Hughes of the SS. Ccdarbank, one- of the first on which the automatic "SOS" alarm was installed.
14bote, the radio room of the Ccdarbank, showing the automatic receiver on the wall at the left, above the operator's table. The second signal bell is at the right and above it, at the center of the top line of the picture. This receiver is permanently tuned to the baud 15 meters on either side of the 600 -meter wave- length on which the "SOS" is sent out. As there is much calling near this ware, a distinctive signal, 12 four -second dashes spaced one second each, is used in this system. When such a signal is picked up by the receiver, which is of the three -tribe regenerative type, it sets in action the polarized relay and selector on the table below it, which can be seen in more detail in the picture below at the lower left.
The alarm device used to send the special call is made in two types, each of which Itas a timing device so that it will send out the signal in the exact method which will operate the selector at the receiver shown below. It is rated as laving a ramie of 200 miles; but would undoubtedly be audible much further in many receivers. It is not impossible, of coupe, that near shore powerful land stations might cause a false alarm; but there would seen to be little danger of this at sea.
We have below a close-up of the receiver itself, with its three tubes mounted horizontally on the front parte!. There are no dials on the set, but only keys for adjustment, as it is to be kept in fixed tune. The switchboard of the power supply is alongside of it, and the telephone to the bridge at the left. All passenger liners and all freighters with a crew of fifty or more, under the British flag, must carry this safety device; and endeavors are being made to bring about similar regulations by other nations. Illustrations (C) Herbert Photos, Inc
www.americanradiohistory.com Radio Arct.s for January, 1929 (23 Radio Does Not Change the Weather
A Popular Theory That Broadcasting Brings Rain and Wind Is Disproved by a Reference to the Records of the Past Fifty Years
By B. Francis I)a.cbiefl ``
title reasons; the greatest sport at present is to blame all climatic vicissitudes on radio! The great towers of the naval radio Many believe that the seasons are chang- station NAA, at Arlington, Va., opposite Washington, carry the ing; we often hear the expression: "The aerial wires of many powerful winters are not what they used to be." It radio transmitters. Does the energy is true that the weather has undergone which they hurl into the air have any effect on the weather.' changes during the habitable state of the earth; but these changes have been so gradual that many generations of people could notice no difference. Without know- ing the length of time which has elapsed I1 is unfortunate for radio that many followers began to shake the ether, there since the beginning of man's reign on earth, otherwise well -informed persons should were prolonged periods of stormy weather it is impossible to estimate the rate at which advance radical theories, to the effect at sea." the climates of the earth have changed. Cli- that much of our unusual weather is Mark Twain once remarked that while matological records have not been kept sys- due to radio activities in the ether. Such everybody talked about the weather, nobody tematically throughout long periods of rumors are being given wide publicity, and did anything about it. If we have an un- years, and we have no direct way of know- the belief that radio is changing our weather usual change in the weather, it becomes the ing how the weather affected the lives of has rapidly spread among many credulous sole topic of conversation, but nothing is primitive nun; though Biblical history tells folk. Recently, no less a personage than done about it. Modern science can as yet us of weather changes which had important the captain of the White Star liner Homeric do nothing to stay the actions of the bearings on the destinies of the bunian race. stated: "Radio waves precipitate rain and weather. But the weather furnishes a topic Within the present era, however, there contri;iute to the strength of gales and other about which many who are very ignorant are records of "years without summers," disturbances of the elements." The tendency believe they are very wise, and they im- seasons of drought and famine, of floods to indict radio whenever weather conditions mediately divulge all sorts of pseudo- scien- and disaster, of hurricanes and tidal waves, are unsatisfactory makes it very difficult for a radio man to refute completely such allegations unless he has actual technical theories and facts at hand. Radio engineers and meteorologists actually know, however, that radio cannot affect the weather in any way; but, on the contrary, the weather often stirs up all sorts of trouble in the radio world. The trained meteorologist will not place any blame on radio, but the radio en- gineer has a right to blame much on the weather. Recently, according to press dispatches, the residents of the English town of Mat- lock framed a petition asking that radio ac- tivities be suspended so that excessive local rainfall might be checked. A farmer in a Southern state sent an urgent telegram to Washington, pleading for a cessation of all radio broadcasting so that a drought then existing could be broken. Others say that, while radio has been developed and per- fected, so have our varied weather phe- nomena increased in violence. Still other persons blame radio for everything, such as increased illness, lawlessness, accidents, and even insanity. LOOK UP THE RECORDS 'l'he New York Times is gifted editorially to comment on events which are of more than passing interest. In a conservative statement the Times has this to say about the charges of the captain of the Homeric, and radio indictments in general: "One suspects that, if the weather reports for the last generation were examined, it would Dr. Starr, whose frank comment on the folly of the "radio-weather" theory appears on the be found that, long before Marconi and his following page, is here observing the automatic machines which make a record in ink of every minute's weather at New York, year in and year out. *Member, American Meteorological Society. (Photo 0 Underwood & Underwood.)
www.americanradiohistory.com 624 Radio News for January, 1929 as well as all other weather variations. Most of these, however, are the extremes of weather which occur at infrequent and ir- regular intervals and are not changes in the established normal climate of any lo- cality.
WEATHER IN TILE OLD DAYS Long before radio was dreamed of, any unusual weather created consternation and excitement among the populace. This was due to the greater ignorance prevailing, and the fact that no records were to be had of previous similar events. We find that the River Thames, in England, in the 17th cen- tury, froze over solidly, a rare and almost unknown occurrence. In 1703 a great storm ñ:::n",*an!!s raged over Europe, and in England it was is its, more destructive than any storm experi- enced either before or since. In 1545 a hail- storm pelted people and animals to death and stripped the trees of their foliage. Other i great hailstorms happened in 1829 and 1838 in Spain and India, and blocks of ice, weigh- On these two pages is a study in contrasts, to make the realer appreciate snore fully :chat "superpower" is. The gigantic turbine generators ing nearly five fell at Muscle Shoals. pictured above, are part pounds, to earth, doing of a 650,000- horse pgvvcr (500,000- kilowatt) plant, more powerful than all radio apparatus great damage. together. Two great hurricanes of modern times occurred in 1889 and 1900; the former, the The memorable Samoan hurricane, is said to Weather Man Prefers His Fiction Straight have averted a war when it destroyed thir- " nOES radio transmission effect weather conditions? Certainly not! I have teen American, British and German war- Ll been told that the combined power sent into the air by all the transmitting ships. The Galveston hurricane was in stations would not be sufficient to ran an electric toy -much less affect weather 1900. The 1926 Miami hurricane has been conditions. The fable that radio affects 'weather conditions is merely part of the exceeded many times previous by greater scientific fiction we read today. Entertaining, but nothing else. hurricanes, and the Porto Rican hurricane "iVe are constantly being deluged by weird plans or devices for the prevention of September, 1928, has counterparts before of bad weather, for bringing on rain, and for a thousand and one other purposes the days of radio. concerning the elements. As theories they are interesting; but when advanced as The year 1816 is popularly described as facts with offer of proof, they are ridiculous. "the year without a smnmer "; a recurrence "Perhaps the best example is that of the young man who canse to my office to of this summerless year was predicted for inform me that a friend of his had invented a method of preventing rain. iVhen I 1927, but it failed to materialize. It is not asked him for some tangible proof, he said: `Do you remember that past few days known whether the sensational sponsor of when you forecast rain and it failed to do so ?' I answered in the affirmative. that prediction based all his calculations on said he, `your forecasts would hare coin about but for my friend -who prevented radio or not. The year of 1900 goes down it by meats of his rain -presenter!'" in history as having the most extended -Da. .T.Am :s H. SCAan. heat wave known to our country. Principal lIeteorolollist. United States Weather Bureau. Our weather is extremely versatile over short periods. There is no doubt, however, that, if regular climatological records had average of the various weather phenomena from the normals established by the records been kept for several thousand years, the of the present age would vary but little of the many centuries past. Regular rec- ords have been kept during the past fifty years of the existence of the U. S. Weather Bureau; a period quite short in comparison with the recorded history of man. How- ever, a definite, normal weather year for many places has been computed from these fifty years' records; so that any single year may be accurately compared to determine whether it is above or below the average. Radio activities have existed for but a few years; the last six or seven registering the greatest development. There have been more severe weather events during the years before radio than have occurred since. The accurately -kept daily records of the weather in the United States for the past fifty show no departures from normal in the past ten or twenty which can be taken by the most prejudiced person as indications that radio is causing variations in our seasons and climate.
AMERICAN WEATHER HISTORY For the purpose of fair comparison the computed weather averages or normals for Boston, Mass., Charleston, S. C., Chicago, Ill., Denver, Colo., Miami, Fla., Memphis, Tenn., New Orleans, La., New York, N. Y., Portland, Me., San Francisco, Calif., Seattle, Above, the high-voltage lead-ins of the transmission lines at Muscle Shoals. The power which Wash., and Washington, D. C., have been these lines unavoidably leak into the air is enormously greater than that of the highest- powered used. These places were because radio stations; but no one suggests that it affects the weather. selected (Photos courtesy General Electric Co.) they have a fairly regular geographical dis-
www.americanradiohistory.com Radio Nc7us for January, 1929 625
trilndion with generally different climates, temperature been more than 4 degrees be- Radin is exonerated, however, of being and are also centers of extensive radio ac- low the normal annual mean. This is quite the cause of droughts and ruinous crop tivities. remarkable, and surely indicates that de- years. And when farmers consider the rec- The lowest temperatures of record seem partures from normal are slight and that ords as they are, and look back over the quite remarkable, since very few have been temperature changes over 50 years have time as they remember it before the days indicated (hiring recent years. The latest been negligible. of radio, they will he glad of radio, for the record which was broken was at Boston, in The annual rainfall reaches its greatest benefits it brings to them. 1918, when a temperature of 14° below zero amount at Miami, with 60 inches, and its Now let us take up the length of the was registered. Other record- breaking low least at Denver, with 14 inches. Of course, growing season; that portion of the year temperatures are as follows: Chicago, 23° there are other places having greater and after the last "killing" frost in spring and below zero in 1872; Denver, 29° below zero less amounts, hut they are not included in before the first one in the fall. This sea- in 1875; New York, 13° below zero in 1917; this selected list of cities. At times the son ranges from 160 days at Denver to and San Francisco, 29° in 1888. All the farmers suffer from dry years, when the practically the entire year of 365 days at other selected places experienced record - rainfall is too little for growing crops. Miami. Records for the shortest growing breaking low temperatures in 1899, when a Years having record -breaking scanty rain- seasons were made at Charleston in 1916, severe cold wave swept over the cast and falls occurred at Chicago in 1901; Miami in and in 1875 at Denver and New York. In south. With the coldest years occurring as 1907; New Orleans in 1899; New York in the central agricultural belt, records for far back as 1875, and low temperatures 1916; Portland in 1883; Seattle in 1911; and short growing seasons were made more than mostly in 1899 and before, it is obvious that Washington in 1894. Rainfall at other 30 years ago-in 1895 at Chicago, and 189:3 radio cannot be charged with causing un- places was nearly normal, but was deficient at Memphis. usually cold weather. mostly before 1907. Wet years have not New York City is a great center of radio I.et us apply the saine yardstick to hot - been so excessive, and have not been con- activity; more power is radiated into the weather records. We find that the highest sidered. air within a hundred miles of New York than at any other one place in the world. The records for a "cold year" and a "short mer" were established at New York about 50 years ago. The highest tempera- ture was recorded seventeen years ago, and the lowest temperature eleven years ago. 'l'he lowest rainfall was in the year 1916, or twelve years ago. Other less important weather records show no particular events in recent years, and the established weather normal has been followed very closely. Near the most powerful radio stations known, when great power (as radio goes) is being radiated from the antenna system, no changes in temperature, humidity, baro- metric pressure, or air movements can he detected with the most accurate instru- ments. Except for the usual results of elec- tric induction, there is no indication that the radio station is radiating any energy. So, why blame radio for unusual weather changes? (For the sante reason that people who hare "aural hallucinations"-that is, hem The scene above is the control and transmitter room of the experimental station 3XN, Whippany, imaginary voices-now blame radio. The New Jersey: the equipment has just been transferred to W1_IV, Cincinnati. This "superpower" reason is simply that the critics do not station is heard halfway round the world; its "superpower" is nearly seventy horsepower! know rclaat they are talking about.- Enmroa.)
temperatures of record occurred as follows: Boston, 104° in 1911; Charleston, 104° in 1879; Chicago, 103° in 1901; Denver, 105° in 1878; Memphis, 104° in 1901; Miami, 96° in 1907; New Orleans, 102° in 1915; New York, 102° in 1911; Portland, 103° in 1911; San Fran- cisco, 101° in 1904; Seattle, 98° in 1903; and Washington presents the most modern rec- ord of all, with 106° in 1918. Thus, radio has not been associated with any of the ex- treme high temperatures of record.
LITTLE YEARLY VARIATION If we take the average or "mean" tem- perature for one year at a time, at any place, and compare it to the "normal" tem- perature (the average for many years) we find that sonic years will be either above or below the average. We are concerned mostly with those which might be termed "coldest years," when the nican temperature was lower than the established normal tem- perature. We see that such years occurred prior to 1917; at that time the mean low temperature was only 1 degree below the normal at Miami. At Chicago and Wash- ington, record below- normal temperatures occurred as far back as 1875; at Memphis An in 1886; San Francisco in 1888; and at the external view of the towers and slender aerial of 3XN; judge how feeble is the energy it remaining places mostly in 1899, 1904 and can handle, compared with the great power plants. At a few miles from these aerials, the energy which can be detected is too small to be described in 1916. In no case has the record annual low "flyposeer." (Photos courtesy Am. Tel. & Tel. Co.)
www.americanradiohistory.com 626 Radio News for January, 1929
V` \\111 Nnt",r'ii .., .I,,;- o - ,'= af9s New in r 411 apparatus described in this department lias been tested in the RADIO NEWS Laboratories and found of high quality in design and construction.
A Power -Amplifier Suited to Standard parts are used in the construc- great demand for a substitute; however, Public- Address Purposes tion of the amplifier, which is built into upon the arrival of the power tube, with its a crackle -finish steel case 3-3/8- inches wide, higher voltage requirements and its heavier THE present wide popularity of the 51/4 inches high, and 17 inches long. All drain from the batteries, the development of dynamic speakers which require field - connections are made to a small panel at power units was rushed to keep up with the coil excitation with 110 -volt direct, current, one end of the case, and the three tubes industry's tube developments. and the recent innovation of adding power project through the top of the case to facili- The first power unit was a "hummy" af- amplifiers to phonographs, have led to the tate their heat radiation. The latter are fair; it generally employed as the rectifier design of a neat, compact amplifier, which a 281 -type rectifier tube, a 226 -type ampli- a 201A -type tube which aided in supplying may be purchased either completely as- fier tube in the first stage, and a 250-type a problematical voltage of 90 or thereabouts. sembled or in kit form. Its components amplifier tube in the last stage. The am- are being marketed by the designers and plifier will operate one speaker with a manufacturers, who have been active in the 90-to- 120-volt field, while a second quality -amplification field for some time (of the 110 -volt A.C. type) can past. be added if desired. This amplifier is particularly adapted for During the early days of the use with a phonograph and an ordinary magnetic pick-up; used in this manner, it has been found to give excellent reproduc- tion of electrically-cut records, with suffi- The external appearance of the new power amplifier shows its compactness; cient volume to fill a small theater at or- its super -power tube makes it capable chestra volume. of serving a large hall. Supplied with current from the house wiring at any voltage between 105 and 120 alternating at 50 to 60 cycles, the amplifier compact delivers the necessary rectified cur- broadcast era, the criterion of a rent to the dynamic speaker's field coil, and receiver's quality was the greatest supplies all necessary "A," "B" and "C" distance at which one could stand power to its own two amplifying tubes. from the loud speaker and still With its input side connected either to the hear its reproduction. Circuits, were designed detector tube of a radio set or to a mag- tubes and speakers netic phonograph pick -up, and marketed on the ability to have their and its output of side across a good dynamic speaker, the particular blasts heard above the roar with result is undistorted the others, which were blasting away reproduction with a under volume running, under control, to the full the same purpose in view. Naturally, was a secondary capacity (approximately 5,000 milliwatts) those conditions, quality of the 250-type tube. consideration. The audio -frequency transformers Proper appreciation of fidelity in repro- used of manufacturers answered the call in this amplifier are of the "Clough" type, duction was born with the development Condenser of wide - the only products they had on hand rated by the manufacturer as having prac- the power tube, the production with - tically a range audio- frequency transformers (a rar- by-pass condensers! This was before they straight -line characteristic from the effects about 50 ity in the early broadcast days), and the had a chance to study properly cycles to the upper limit of the when audible frequency concentration on the problems of tone qual- of high-voltage surges on condensers range. The design of power units. The each transformer comprises an auto-trans- ity by the loud-speaker engineers. The employed as filters in well known to a good many read- former, a resistor and a blocking condenser, first power tube to be marketed aroused results are with gusto and so- all mounted in one case and connected in no great comment, aside from that gener- ers- condensers popped a subsequent discour- circuit. External connections ally accompanying a new article of com- ciability, producing in effect on the morale of the con- are made just as to any trans- merce; but the real niche it occupies aging former of the conventional radio's Hall of Fame is that of the progen- structors. itor of "B" power units. So long as two Time ironed out the engineering diffi- blocks of "B" batteries culties and, by the time the third power were sufficient to oper- tube (the 171) was developed, its require- ate the average set, ment of 180 volts was met by the manu- there had been no facturers with designs in a state of elec- trical and mechanical perfection which spoke well for the further development of power amplifying units. When the next power amplifier tube developed (the 210) required a plate potential of 400 volts, the question was raised again as to the ability of the available apparatus to withstand the brute force of that voltage and its surges. It did so and, for that matter, still is giv- ing service. primary-secondary type. The development of the amplifier de- The direct plate current scribed in this section was the continuation of the preceding tube of the above -mentioned pioneering. As can passes through the resistor alone, while the be seen in its circuit diagram (next page) A.C. signal impulses flow through only the it comprises two stages of audio- frequency amplification; the second of which includes condenser and the lower or primary portion The power amplifier with of the amplifying auto -transformer (T1). its metal cabinet removed. a 250 -type tube. The plate voltages for
www.americanradiohistory.com Radio Ncws for January, 1929 627
to tuning the receiver -merely place the TO TO aerial lead on the adapter's binding -post. T1 T2 SPEAKER FIELD It r 0 0 is necessary in this case to tune the adapter 1 226 r 1 250 --. like a short -wave set for "zero- beat" recep- 75 V 110 V tion. See page 553 of our December issue. I a AC As can be seen from the illustrations, 281 sim- 1500 plicity marks the construction of this OHMS P adapter. All parts are io0 mounted on a black N bakelite panel, a which is set into the top of a 1 5 V cabinet measuring only 7 x 5% inches on 1{ 1 2 2 2 P ¡a the base and 234 inches high. Vernier con- trol is provided for the tuning condenser, ô 75 b o V while the regeneration condenser is con- CONDENSER 0 BANK -J trolled by a knob, no fine control of oscil- lation being necessary. 2000 OHMS 60.000 In following the circuit lettering, 1,1 is OHMS the antenna winding placed permanently about the base of the coil form; L3 is a radio -frequency choke coil of standard in- The schematic diagram of the 250 -type power amplifier described on the previous page shows that ductive value; 111 is a 7- megohui grid leak; it is self -contained; in addition to supplying direct current for an electrodynamic speaker, the C3 a .0002.5 -mf. grid condenser, and P the field winding of which serves as part of Nue filter system. It will operate Irons a phonograph pick -up. adapter plug which is inserted into the 11.F. or detector socket of the broadcast receiver. these tubes are supplied by a step -up power the has a complete coverage of the adapter The type of coil used can be seen from transformer; filaments of the three 17 84 the channels ranging from to meters. the external illustration of the adapter; tubes (250, 226, 281) in this unit are heated Should the wavelength range of the re- Nos. 1 and 3 being indicated by A; No. 2 is by three suitable windings on the power ceiver be found insufficient, additional coils shown in its socket, in the position of use. transformer. A novel feature of the filter may be wound on a standard UX tube base, Manufacturer: A -C Dayton Company, system employed in this unit is that the providing care is exercised in the proper Dayton, Ohio. field winding of the dynamic speaker is used wiring of connections to the prongs. as the choke coil. A variable potentiom- Installation on the average run of tuned - eter across the filament of the first ampli- radio- frequency receivers, whether battery New A. C. Tubes of High -Mu fier tube (226 -type) is used to control the or A.C. operated, is a simple matter; first hum. Type for R. F. or A. F. Manufacturer: Silver-Marshall, Inc, Chi- NER' "high -nu" tubes which differ front cago, Ill. others previously available, in that the filaments are heated by alternating current, like the 226 -type, are now available for in- A Short -Wave Converter for corporation in electric sets, either as R.F. the Parlor Receiver or A.F. amplifiers, particularly for use with impedance or resistance coupling. Inasmuch Wthe present interest in short- as these tubes have a rating waves and the commercial demand for of 1.05 am- peres at 1.5 volts, the filament a short -wave unit adapter that can be con- wiring of a set designed for direct- current tubes nected to the amplifier of the average broad - may not have sufficient carrying capacity for the cast receiver with little or no change in relatively wiring, there heavy current and it is frequently have appeared on the market necessary to rewire a number of items this portion of the set. such well suited for the Over line -voltage variations purpose in view. to an extent which may he expected Among these reasonably, no ap- is the adapter illustrated preciable change occurred herewith. It employs the conventional re- in the character- istics of the tube. The recommended generative circuit with a semi -aperiodic pri- fila- ment voltage for this tube is L35 volts mary, and a fixed tickler which is capaci- and, tively tuned, as indicated in the circuit dia- gram, by the midget condenser, C2. This method of controlling regeneration is prac- tically trouble -proof and the one generally employed by the majority of short -wave experimenters. It can be used with anv broadcast re- ceiver using a UX socket in the first radio - The adapter is compactly rased in a small frequency or detector stage. Three plug -in box. which may be laid on a table or on the receiver coils are supplied with each adapter; coil cabinet. Extra coils A fit into the socket L2, to change over three wavebands. No. 1 has a wavelength range between 17 to 29 meters. Coil No. 2 covers from 27 to 48 adjust the receiver to a high wavelength, meters, and coil No. 3 is from 47 to 84 with all dials tuned in and all controls set, meters. Thus, it can be seen, with the set just as though a (listant station was being tuned in use any wavelength between 450 and 500 meters where no local station is re- ceived. Remove the first R.F. tube and in- sert the cable plug of adapter in its socket, and then place the tube in the adapter socket. The aerial lead must be removed from the receiver and connected to the "an- tenna" binding -post on the adapter, which is then ready for tuning. The adapter then operates as a frequency- changer, and the R.F. unit as an intermediate amplifier. When adapting a regenerative receiver, insert the adapter's plug into the detector socket and the tube into the adapter's (4) The circuit of the adapter, above, is that of socket, making sure to provide the of All parts of the adapter are mounted on the a standard short -wave set, from which plate it dif- panel, a bark view of which is shoran fers only in using an external the detector with 2214 or 45 volts "B" sup- above. amplifier -that It will be seen how simple is the construction; of the receiver with which it is used. ply. No adjustments need be made here as the two condensers arc the only controls.
www.americanradiohistory.com 628 Radio News for January, 1929 if the tube is burned at a higher voltage than this, some increase in signal strength L2 will result; but the useful life will be short- r + ened. Wherever it is used, a center -tap re- o e TICKLER C3 is neces- ¡ R. F. CHOKE sistor or the potentiometer method PRIMARY c. 11 sary to bring the grid return to electrical center. As much as 8% unbalance will re- CAP V1 L3 sult in a noticeable ripple voltage. The tube should not be used without applying a grid OUTPUT bias, the proper value of which may be de- 0 LI termined from an accompanying curve. e Manufacturer: CeCo Manufacturing Co., Inc., Providence, R. I. SECONDARY R4 R1
R2 ANTENNA IMPEDANCE SW Short -Wave Kit Contains Parts UNIT C5 C6 GROUND-, for Screen -Grid Tuning Unit o RADIO fans who desire to assemble B+ B+ A- B- A+ short -wave receivers with a minimum 45V. 135V. C+ of effort and bother will find a very satis- factory answer to their requirements in a A feature of this short-wave set is the use of the special inductor LI in the aperiodic R.F. stage, which is made advantageous by the use of the high- amplification screen -grid tube VI. The by- kit of parts recently placed on the market passed resistor R4 is the regeneration control, the tickler coil being fixed. by a New England manufacturer; it con- ex- tains the components necessary for an two small brackets and, also, the frame of to be confused with a grid leak or a fila- cellent two -tube tuner, to which may be the tuning condenser. ment resistor. added an external audio- frequency amplifier One by -pass condenser, C4, connected of any of the standard types. 'l'he first The parts on the base panel are laid out across the variable resistor R4, is mounted con- tube, of the 222 (screen -grid) variety, acts in such a manner that most of the on the under side of the base panel, and nections in the set are only an inch or as a radio -frequency amplifier, and the is not visible in the photographs reproduced second, a standard 201A, as a regenerative two long; the longest wires are in the here. filament circuit, where length is not so detector. The binding posts are mounted along The kit contains the following parts: a detrimental a factor. All the wires, except the short one running to the cap of the î x 12 -inch front panel, drilled for a ver- nier dial, a filament switch and a variable screen -grid tube, are on the under side of and do show. resistor; a 9 x 11 -inch base panel, drilled this panel, not for binding posts and by -pass condensers, The wiring diagram of the tuner is shown fitted with receptacles for tubes and a on this page. It will be seen that the plug -in coil, and clips for filament ballast grid circuit of the screen -grid tube V1 is resistors, grid leads and R.F. choke coils; not tuned; the aerial and ground being a tuning condenser of .00014 -mf. capacity, coupled to it directly by the antenna im- with an illuminated vernier dial; four plug- pedance unit (R.F. choke) L1. The screen - in coils to cover the short -wave bands from grid tube is coupled to the detector tube, 15 to 150 meters; and two R.F. choke coils. V2, by one of the plug -in coils; each of To complete the tuner, the constructor which contains three windings: primary, must have also two filament -ballast resis- secondary and tickler. A complete coil is tors, a grid leak, eight binding posts, five 6 shown within the dotted rectangle marked The short panel, with handsome illuminated L2. The of the screen-grid tube is small fixed condensers, a filament switch, vernier dial, and the two controls required by plate a universal -range variable resistor (0 -to every regenerative circuit. fed 135 volts through the primary, and the 100,000 ohms) and, of course, the 222 and screen -grid electrode is fed 45 volts, 201A tubes. the back edge of the base panel. The two directly. These two "B" leads are by- The front panel holds only the tuning other by-pass condensers C5 and C6 are passed by the 0.5 -mf. condensers C6 and C5, condenser Cl (or rather the vernier dial behind the screen -grid tube V1, and one respectively. to which the condenser is mounted) the R.F. choke coil, L3, is behind the detector The detector circuit is one of the usual filament switch SW, and the regeneration - tube V2. The receptacle for the plug-in regenerative type. The tickler is fixed control resistor 114. The base panel is coils is directly behind the variable con- (being one of the three windings on the fastened to the upright one by means of denser; in the accompanying back view of plug -in coils), and regeneration is con- a completely - assem- trolled by the variable resistor R4, in the bled tuner, one of the plate circuit. The tickler is in shunt with coils, L2, is shown in the plate circuit, the condenser C3 (.006 - its receptacle. mf.) being inserted to prevent the "B" A special R.F. choke battery from short -circuiting through the coil, LI, which re- tickler to the filament. The R.F. choke L3 sembles in appearance keeps the R.F. component of the plate cur- a grid leak, is mount- rent out of the "B" leads, and makes it ed in a pair of cups stay in the tickler circuit. at one side of the The complete tuner shown in the accom- screen -grid tube. Par- panying photographs was assembled in the ticular attention is RADIO NEWS Laboratories from a founda- drawn to this choke, tion kit supplied by the manufacturer. It because it seems likely worked very well, its operation being parti- cularly pleasing in that there were no "dead spots" in the tuning. Although the screen -grid tube is not shielded and its is untuned, furnished a With practically no ex- grid circuit it posed wiring, the set definite amplification on all frequencies built from this short-wave with the range of the plug -in coils. kit is especially neat in finish. The plug -in coil A neat metal cabinet for this receiver is L2, clear of other parts, available. is easy to grasp and re- The National Company, move or insert when Manufacturer: desired. Malden, Mass.
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turns for the grid coil, 30 turns for the plate coil and a four -turn pick -up coil is wound between the two with a % -inch space on each side of the center coil to separate the three. A .00025 -mf. variable condenser connected across the grid and plate coils is used to control the oscillator which, like the detector, employs a 201A -type tube. In connecting the oscillator coupler, the outside terminals of the coil should be con- nected to the plate and grid terminals of the oscillator socket, or the oscillator con- denser itself; and the inside terminals of the respective coils connected to the filament and "B +" supply. One end of the pick -up coil connects to the center -tap of the loop antenna, and the other to the "A -" battery line. 'l'he output terminal strip shown in the The diagram of the screen -grid intermediate amplifier and fundamental connections; each stage, of course, is fully shielded. The amplification obtained is enormous, being sufficient to bring up the circuit diagram includes an unmarked post, faintest signal that can appear above the noise level. The high intermediate frequency, 450 kr., which is connected to an unused 1 -mf. sec- is such as to give a one -spot effect over the. dial when tuning in stations on the broadcast band. tion of one of the by -pass condensers. The other side of this section is connected to the An Intermediate Amplifier of condenser (C2) and a grid -leak (R) are in- negative battery line within the amplifier, cluded in the circuit. No screen -grid cap is and the constructor may use this capacity Distinctive Character found in this shield, as the tube used here for whatever purpose he desires. The other ASCREEN-GRID intermediate radio - is a 112A (V2) of the regular UX type. two posts on this strip are connected to the frequency amplifier for superhetero- Additional components for the assembly primary of the first audio-frequency trans- dyne operation has been marketed for the of a complete receiver include a suitable former, if a coupling of this type is added benefit of the constructor who wishes to de- center -tapped loop tuned by a .0005 -mf. to the assembly; the "Out" post goes to sign and assemble his own superheterodyne variable condenser, which is connected the "P" post of the transformer, and the receiver. The components which make up across the terminals of the loop; a 201A- "B" post of the latter is connected to the the amplifier are assembled on a metal "B 135" post on the terminal strip and the chassis and have individual copper shields corresponding voltage supply: for each stage of amplification, as well as Manufacturer: High Frequency Labora- for the second detector, which is included tories, Chicago, HI. in the assembly. The intermediate ampli- fiers operate on a frequency of 450 kilo- cycles and are stated to give a measured New Outlet- Control Designed gain of 65 per stage under actual operating For Built -In Radio Wiring conditions. The complete unit is arranged item, though not for sub -panel wiring, and is obtainable com- A NEW radically new pletely wired and assembled; its over -all size 11. in design, is a piece of apparatus de- signed for the use of those who may wish is 11% x 51/4 x 67/ inches. Three 222 -type to wire a number screen -grid tubes and one 112A -type are re- building for a of loud quired for the operation of the unit. The illustration of the assembled amplifier speakers and desire an individual volume fails, however, to give the appearance control with speaker. is As shown in the diagram, the circuit is striking each It especially of the burnished -copper individual.stage cans. convenient for that of the conventional intermediate ampli- apartments, hospitals and hotels fier except that, instead of the usual three - where multiple outlets with separate type tube, as a to controls are required. element tubes, screen -grid tubes are used. serving first detector, The plate measures which loop is directly; and a x The substitution of these for the 201A -type the connected .5 2yt inches and is finished in statuary 25,000-ohm potentiometer. An oscillator makes for a noticeable increase in amplifica- bronze with an artistic scroll effect. The coil, which required the dis- tion per stage; providing the proper pre- is to make up volume control is obtained by a standard tinctive circuit of every superheterodyne, variable cautions are taken to come up to the en- midget resistor, of a type which tube manufac- may be obtained from the same manufac- has been marketed by the manufacturer for gineered specifications of the turers. turer. It consists of three windings on a some time past, and is well known for its -inch diameter tube; No. 30 enameled electrical In each of the first three shields (the l' / durability and efficiency. 'l'he wire is used for the three windings three intermediate stages), are found a -32 (Continued on ¡inge lin-i) special intermediate- frequency transformer (T), a miniature condenser block contain- ing three by -pass condensers, and a tube socket of the standard UX -type. Mounted upon each transformer is a small variable condenser of the screw -adjustment type (CI), by means of which the transformer is tuned to resonance. Extending from the first three intermediate transformers are shown three caps (indicated as S) which slip over the metal caps of their respective tubes; this tube cap, the distinctive feature of the screen -grid tube, is the external con- necting post for the control -grid of the tube. The tuned air -core transformers T have duo -lateral primary and secondary windings of No. 32 S.S.C. wire, each on the usual wooden slotted- bobbin form. The ar- rangement gives very short leads. 'l'he fourth and last shield houses the sec- ond detector circuit and, like the others, contains a triple condenser block and an intermediate- frequency transformer with its .4 riet., of the amplifier an its base, with the shield cans removed; the by -pass blocks are behind compensating condenser. However, since the tube sockets. The tuned transformers T are behind their bakelite covers; the screen-grid this tube functions as a detector, a grid- clip leads S, like all other connections, are very divert. Condensers Cl are adjustable.
www.americanradiohistory.com 630 Radio News for January, 1929 elevisio
The Latest Developments in the Field By Robert Hertzberg
THE television plans of numerous sta- its activities was acknowledged by those tions have been seriously disrupted present, but it was the unanimous opinion by the recent order of the Federal that a great deal of immediate good would Radio Commission calling for an en- be done for both the industry and the public tire rearrangement of the broadcasting situ- if even temporary standards were drawn ation in the United States. Practically none up and adopted. Mr. C. Francis Jenkins, of the broadcasters escaped some change in of Washington, D. C., the noted inventor, wavelength, power or hours of operation; described the exactly parallel efforts of mo- and, as a result, the managers of those sta- tion- picture pioneers during the early days tions still `on the air" are very much "up of the "movies," and stated that the motion - in the air" regarding their general pro- picture business had benefited greatly by grams. At the time this article was writ- eventually adopting the suggestions of a ten, the order had not yet gone into effect, committee of cinema experts similar to the and very few stations knew just what they television committee of the R. M. A. would be doing after it did go into effect. 11,,,,, 1,1,,,,,,,,11,,,,,,,,1,,,,,1,,,,,111111111111 l,,,,,,l MI1111,,.,,,,, 1111,,,,,,,,1111111,,,,,llll .l,.11lll This state of temporary uncertainty has naturally had a reaction upon designers and ON November 2, 1928, the Federal manufacturers of television apparatus. It Radio Commission issued an order has made some manufacturers delay their restricting the hours of still- picture plans for the production of television re- and television broadcasting, at least ceivers and accessories for home use; but it until January 1, 1929, when the com- has by no means halted the progress of the mission will again take under con- art. value of this service sideration the In general construction, the television trans- THE FIRST TELEVISION CONFERENCE to the advancement of radio. mitter using the light reflectors greatly re- Picture and television broadcasting sembles the machine in daily use at WRNY. That television is actually emerging from Above: Mr. E. Manuel showing how the sub- developing into a is permitted on frequencies above the laboratory stage and meters) ject poses before the bank of photoelectric cells. proposition is made evident by 1,500 kilocycles (below 200 commercial special authorization of the the recent action of the Radio Manufac- only by in forming a Television commission, which will determine the same number of holes in their scanning turers Association ad- Committee; the announced exact frequencies to be used. In. mechanisms, the actual figures ranging from Standardization will be al- of which is to suggest standards of dition, such broadcasting 24 to 60. It was thought that a 48 -hole disc purpose the 200- equipment and definitions of tele- lowed to a limited extent on is more flexible than the others, so the com- television band. the vision terms, in order to relieve some of the 550 -meter broadcast For mittee decided on the following: the commission orders: confusion now surrounding the art. latter range, "LINES PER FRAME: It is recommended that of which Mr. D. R. Re- (1) that the band of frequencies oc- the number of lines per frame in a television The committee, shall is chairman, met for the first time cupied by any such transmission system be 48." plogle ten kilocycles; and in Chicago on October 9, 1928, during the be not wider than the and television The matter of disc speed, or rather week of the Chicago radio show, and did (2) that such picture was made limited to periods of number of frames per second, some commendable work. The limitation of broadcasting be the subject of considerable discussion. It than one hour per day, and not more was agreed that it would be better to adapt between 6 and 11 p. m. forbidden existing motors to the needs of television,
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,,,,,,,,111,,,,,1,1,,,,, 1,,,,,,,,,,, 1,,,,,,.,,,,,,,,,,,,,,,,,,,,,I 111111 rather than to force motor manufacturers to produce special machines. Mr. Jenkins "STANDARDIZING" TELEVISION stated that ordinary synchronous motors are first problem taken up was the direc- highly satisfactory for the purpose, and can The scanning tion of scanning. The fact was brought out be adapted readily to television with the aid of inexpensive that there is no difference in actual efficacy mechanisms between the top -to- bottom and bottom -to- gears. A standard 1,800- r.p.m. synchronous top methods; although most of the present motor, for instance, working through 1:2 television systems use the former. It was reduction gears, will turn a scanning mech- 15 frames suggested that the scanning be done just as anism at 900 r.p.m., producing voiced the opin- one reads a book; so, accordingly, the com- per second. Mr. Jenkins as the motion- mittee agreed on the following: ion that, inasmuch standard rate is 16 per second, "SCANNING: It is recommended that picture projection 15 second would be scanning at the receiving end be from top a rate of frames per and from left to right, as the entirely acceptable; the slight difference not to bottom the of observer would see it." This was amended being at all serious from standpoint moving image. Since the 15 frame-per- later to read: "SCANNING: It is recom- the is so conveniently with mended that scanning at the receiving end second rate obtained available synchronous motors, this be from left to right and from top to bot- widely was accepted. The formal state- tom in uninterrupted sequence." number reads: Time next matter was that of the number ment What you would face if you were being televised. of lines per "frame "; the word "frame" first "FRAMES PER SECOND: It is recommended The polished reflectors catch the rays of light being defined as the scanned area. It ap- that 15 frames per second be adopted as reflected from your head, and concentrate them few experimenters are using the the standard rate." on the photoelectric cells. peared that
www.americanradiohistory.com Radio News for January, 1929 631
unlimited so far as size is concerned and Television would permit the broadcasting by television Broadcasting Schedules of pictures which could be reproduced on a THE stations listed below are known definitely by RADIO NEWS to have television screen the size of a standard motion -picture transmitters. Because of the temporary confusion into which the American screen in any theatre; or on the other ex- broadcast stations have been thrown by the new wavelength- allocation order, com- treme, as small as desired in any home; and plete hour-by -hour schedules cannot be printed in this issue. Consult your local permits the reproduction of the finest of newspaper for last- minute changes. details, action and proper perspective of WRNY, Coytesville, N. J.: 297 meters; single -spiral, 48 -hole disc, 450 r.p.m. any object. W2XAL, same location and schedule as WRNY: 30.91 meters. "The new invention uses five or any other WCFL, Chicago, Ill.: 309 meters; single- spiral, 48 -hole disc, 900 r.p.m. uneven number of photoelectric cells, W'3XK, Washington, D. C.: 46.72 meters; Jenkins "radio movies "; can 1w mounted upon the periphery of a heavy. picked up with single-spiral, 48 -hole disc, 900 r.p.m. From 8.00 to 9.00 p. cast -aluminum disc. This disc differs from E. S. T., on Monday, Wednesday and Friday nights. the usual scanning disc previously employed W1XAY, Lexington, Mass.: 61.5 meters; television and "radio movies "; single - in that it revolves both on its axis and spiral, 48 -hole disc, 900 r.p.m. longitudinally therewith; giving the effect, WGY, Schenectady, N. Y.: 380 meters; single- spiral, 24 -hole disc, 1,200 r.p.m. when in motion, of a revolving globe. On Also W2XAF, 31.40 meters, and W2XAD, 21.96 meters, associated with WGY. the outside edge of this disc, which may be WIBO, Chicago, Ill.: 526 meters; three- spiral disc, 15 holes per spiral, 900 of any size, depending on the dimensions of r.p.m.; Sanabria system. the television pictures to be transmitted, are WMAQ, Chicagò, Ill.: 447.5 meters; three-spiral disc, 15 holes per spiral, mounted super -sensitive photoelectric cells 900 r.p.m.; Sanabria system. or glow lamps which revolve with it. A number of other stations in various parts of the country are supposed to have "A commutator is arranged to connect television transmitters in operation; but are not listed above because they have not only that cell passing through the `sphere of answered, or even acknowledged, telegraphed requests from RADIO NEWS for informa- vision' in the transmitting or receiving cir- tion about their apparatus. cuit. This sphere of vision is a portion of the revolving outer globe -surface, upon which the image to be transmitted is focused . by means of a high -speed photographic lens or reproduced by the receptor through vari- WHAT IS TELEVISION? A NEW DISC SYSTEM ations in light intensity of the glow -lamps The next matter brought up was that of Shortly before this number of RAmo as they pass through this sphere of vision. the definition of television terms. A dozen NEWS went to press we received a statement "The ratio of the revolutions of the re- different definitions of the word "television" from the Kodel Electric and Manufacturing volving disc around its center and the revo- itself were offered, but all were too long Company of Cincinnati, Ohio, announcing lutions of the revolving fork or axle carry- or unwieldy. They were finally condensed the development of a "new and entirely ing the saine (which revolves at right angles into three words: vision by radio; this defi- different method of television which has thereto) is uneven; so that each successive nition being adopted tentatively by the been perfected to the point whereby it is tube as it enters and moves across the committee. now up to the manufacturers of photoelec- sphere of vision sloes not travel in a straight Mr. Replogle voiced the opinion that it tric cells to build a new cell of sufficient line, but develops several spirals due to the would be desirable to classify the different sensitivity to answer the requirements of combination of movements. Since each suc- existing systems of television transmission, this new principle of television." The ap- cessive tube enters this sphere of vision in order to clarify television articles and aid paratus is still in the experimental stage slightly out of place from the preceding one, engineers in their considerations of amplifi- and no illustrations of it can be published this causes a complete overlapping of the ers and other equipment. After much dis- in this number. However, we expect to various spirals produced by the cells in their cussion the following recommended defini- show some as soon as they are made avail- travels; and due to the combined speed of tions were agreed upon: able. To quote the statement further: the disc movements and number of cells em- "DIRECT FLOOD LIGHTING: A system wherein "This new principle overcomes the disad- ployed, an enormous number of closely in- the object is flooded with light which passes vantages of the scanning disc, in that it is (Continued on page 666) through it into the transmitter pick-up." ('Phis covers certain "radio- movie" trans- mitters.) "INDIRECT FLOOD LIGHTING: A system wherein the object is flooded with light which is reflected into the transmitter pick -up." (This takes in some of the Baird machines, and the one described by Theo- dore H. Nakken on page 20 of RADIO NEWS for July, 1928.) "DIRECT SPOT LIGHTING: A system wherein a spot of light passes through the object into the transmitter pick -up." (Included in this category is the Jenkins "radio- movie" outfit described in RAmo Ni:ws for August, 1928.) "INDIRECT SPOT LIGHTING: A systein wherein the object is scanned by a spot of light which is reflected into the transmitter pick-up." (This takes in the commonest type of television machine, such as those used by WGY, WRNY, WIBO, WMAQ and others.) The last matter discussed by the commit- tee was the choice of a suitable name for the source of illumination in a television receiver. Television lamp was finally chosen as the simplest and most suitable term. RADIO NEWS, as the most widely read radio magazine in the world, is glad to adopt for its own use the terms and defini- tions listed herein, and wishes to congratu- The new television transmitter constructed by John Geloso (right, seated) is extremely compact, late the Television Standardization Commit- but as efficient as many larger machines. Mr. I. Goldberg, president of the Pilot Electric is standing in front of the Mfg Co., tee on its initial efforts. arc light, resting his land behind the scanning disc. The amplifier is built into time vertical panel.
www.americanradiohistory.com Radio News for January, 1929 High Frequencies for Color Television Mechanism Required to Produce Images in True Colors Will Present Few Difficulties, But Great Width of Fre- quency Bands Will Create Some Problems of Transmission
By C. Sterling Gleason
SOME day television will not be lim- green, blue, yellow, orange, violet, brown -" ited to the dull monotony of mere he names the colors and, as he calls each, an black and white, but will be accom- operator holds before the television lamp by plished in all the colors of the rain- which the received picture is built up, a transparent screen or slide of that color, so bow. A short time later, some manufac- intensity is automati- turer will place upon the market apparatus that the light, whose televisor itself, is for transmitting images in their natural cally regulated by the given color. a scheme colors, and the reproduction will be so life- the proper Such would work very well-if it were fast like and realistic that everyone will admit enough. But in television, the whole image, radio, so long in its infancy, has grown that consisting of many thousand unit areas, to full stature, to take its place beside in- china -painting, bridge, must be scanned several times each second. terpretative dancing, of and other full -fledged arts and This means that hundreds of thousands the movies, dots must be analyzed, transmitted, and re- sciences. rapidity far be- is not as remote as it produced every second -a This possibility yond human possibilities. may seem at first glance. Color television not greatly different from Before considering the method of trans- meets obstacles lating color into electrical impulses let us nor more difficult than those which now pre- application of television. recall a simple fact in optics. Every woman vent the extensive cloth purchased in the store television outfits can be adapted knows that Ordinary under artificial illumination often appears to color vision simply by the addition of which will analyze each entirely different in daylight. The reason is some mechanism that daylight contains all frequencies of elementary area of the picture as to its so that at the re- Mr. Gleason is well known to our readers as light, while in the artificial light, certain color and tone intensity; often be- proper color will be selected a contriver of humorous stories, each of which, wavelengths predominate, others ceiving end the however, is based on a phenomenon of radia- picture the screen in the necessary ing entirely absent. A colored and thrown upon tion. This article is a serious consideration viewed red light appears all out of of the scientific side of color television. under intensity. proportion -certain portions receive undue A SIMULTANEOUS METHOD prominence, others are thrown into ob- the use of the "scanning disc," by means of scurity. If the same picture is seen under accomplished? A how could this be which all the unit areas of the screen are a blue light, its aspect is entirely different. method is suggested by the fact that various covered in rotation instead of being pre- properties Areas which under red light were dim are materials showing photoelectric sented independently and simultaneously; now accentuated, other portions which were respond most strongly each to a certain a cell and ma- thus enabling single photoelectric bright are darkened. Why? Simply be- color or frequency of light. For each transmission channel to handle all the vision of the of light cause, under red light, the portions terial there is a definite frequency impulses. It is made possible by the tendency picture normally red reflected the light to at which photoelectric activity commences, over" after being stimu- critical of the eye to "hold the eye; those colored otherwise absorbed and this activity reaches a peak at a lated. So long as the entire image is pre- be it. When blue light is used, those portions frequency. If this selective effect can as a unit, at least fif- color sented, serially or responsive to that region of the spectrum intensified and regulated, by means of teen times per second, the eye will fuse the cells, come into prominence, the light being "re- filters or otherwise, three photoelectric individual impulses into a complete picture. the eye, while other portions primary colors, radiated" to each sensitive to one of the absorb it. three separate tele- SUCCESSIVE COLORED IMAGES might be connected to Suppose a white object-that is, one vision transmitters. If, then, three receiv- Here is a key to color television. If the flashes a second which reflects all frequencies of light -is ing outfits were arranged to throw their eye will blend fifteen short fuse viewed first under red light, then under light upon the same screen, the combined into a continuous picture, it will surely colored fragments as well. Suppose, then, blue, the two colors being alternated very images, each representing the amount of a to re- that the transmitter is equipped with a de- rapidly. Because the eye continues primary color in the original scene, would sec- in vice causing it to respond first to the reds spond to the light for a fraction of a be superimposed to reproduce the image removed, the two the in the image, then to the yellows, then to ond after the stimulus is its natural colors. At each moment, into one-a purple. Let area of the the blues. The receiver synchronously re- colors are blended light falling upon an elementary three colors be alternated -red, green, and would be the resultant of whatever produces the image according to the rela- screen impulses it receives; blue -violet, the optical primary colors -and yellow, and blue light was being pro- tive strength of the red, then in yellow, the resulting color is some shade of grey, jected from the three receiving sets; and presenting it first in red, The whole cycle repeats it- some neutral color; its exact shade depend- the quantity of each color of light would be then in blue. of the often enough to allow the eye to blend ing upon the relative proportions that dictated by that particular receiving self by rapidly al- the impressions into a smooth picture. Since mixture. It is apparent that, connection or channel. ternating the primary color., we may ob- a method is, of course, so compli- red and yellow make purple, yellow and Such yellow and blue tain the effect of any color we wish, just as and would require such an accuracy blue make green, and red, cated, color, the combina- an artist mixes pigments to get the desired of synchronization, as to be entirely out of make grey or a neutral the colors in varying pro- tones. the question. Just as the first suggested tion of primary as many sepa- portions will cause the image to be repro- TRIPLE COLOR ANALYSIS television system (requiring to illuminate and connecting cir- duced in its natural colors. This, then, is our method: rate photoelectric cells televised with light of the areas of the screen) was But how can the transmitter analyze the the object being cuits as elementary primary colors -alternated. Each so this color system would colors of the object? W. may image a three too complicated; colors by an op- portion of the object responds to its own many possibilities of error in syn- scene being "televised" in allow too and reflects more or less light to the . and in getting the right pro- erator sitting, microphone in hand, beside color, chronization outfit, and describing photoelectric cell, thereby translating the of color to be practical. Now the an ordinary television portions of the picture as it image into variations corresponding to the advance, by which the objections to each dot or unit area great the aperture. "Red, red, light and shade values of that particular the early method were escaped from, was came opposite
www.americanradiohistory.com Radio News for January, 1929 633 color. So far as the electrical characteris- into play once more. (The reader will at transparency identical with that at the tics of the output are concerned, the trans- once note the identity of this layout with the transmitter, and of course revolving syn- mitted rendition of the image is not different Baird color- television system, described in chronously, so that the picture is viewed from ordinary black- and -white -image cur- our October issue; the details of which had through the right color at the right time. rents. The coloring is entirely an illusion not been published when this manuscript was Thus, the three versions of the picture arc of the eye, just as the motion in motion pic- received.- FmToa.) superimposed, resulting in the reconstruc- tures is purely imaginary. The receiver At the receiving end, the motor, running tion of the picture in its natural colors. gives the primary colors synchronously with in synchronism with that at the sending sta- Still another method is conceivable. Let the transmitter, the photoelectric cell.regu- tion, carries upon its shaft a disc exactly the light, after passing through the scanning, lates the amount of each color going into similar to that used for transmission. Out disc and lenses, be directed into a prism, the combination, and the rapidity with of the ether comes an electrical impulse which breaks it up into its constituent col- which the alternation occurs enables the which, traveling swiftly through the ampli- ors, producing a rainbow -like spectrum. A eye to fuse the separate impulses into a fier and associated circuits, flashes the tele- revolving disc passes between this prism composite image in natural colors. vision lamp behind the scanning disc. Col- and the photoelectric cell, traversing lisp Let us visualize the operation of a trans- ored by the glass slide or transparent screen, spectrum so that the passage of light of one mitter operating according to these prin- through the hole in the scanning disc at that color only is permitted at a time. The re- ciples. Instead of the standard scanning moment before the aperture passes a ray ceiver employs a similar arrangement. The disk of black-and -white television, let us use of red light, which fluctuates from bright to light passing from the local source (which, one of the same design, except that instead dark, exactly as the photoelectric cell of unlike a neon lamp, must be white) is of each of the spiralled holes through the distant transmitter analyzes the" object. broken into its constituents; the disc then which the light passes (in many systems A single line of the picture is built up in allowing each color to emerge in its turn. containing a lens to focus the light), it con- red, then immediately in green, then in blue - The slotted disc is geared to advance one tains three; those of each trio being close violet. In a fraction of a second the whole color each time the picture is scanned. This together and equidistant from the center. picture has been traversed -too rapidly for method, while possibly resulting in greater The line traced by a scanning hole is thus the eye to see each change individually. It fidelity of color, would not only be much covered three times in succession. Before sees, not a rapidly- changing series of lines more critical of adjustment, but would re- each of these holes or lenses is set a col- in primary colors, but the result of blend- quire an enormously 'high speed of scan- ored, transparent disc or screen of one of ing of these colors into their proper pro- ning to prevent flicker. Since a series of the primary colors, so that the light is col- portions: a picture in the true colors of color gradations must intervene between ored in passing. A single hole in the scan- Nature! the reproductions of corresponding points in disc comes opposite the aperture, ad- successive cycles, the eye would have to ning REFINEMENTS OF THE METHOD mitting a thin pencil of light -red light, hold over the images a comparatively long which is reflected to the photoelectric cells Let us simplify this method still further. time; while at the same time each color is in amounts depending upon the amount of In front of the ordinary scanning disc of shown for so brief a time that the illumi- red contained in each unit area of the ob- black -and -white television, let us place a nation of the whole picture is reduced. ject. As the ray reaches the edge of the circular disc of a transparent material These systems seem delightfully simple in field and is cut off by the aperture, another (Fig. 1) divided into three pie -shaped sec- theory. The actual application is, of course, simultaneously appears and retraces the line tors, each of a primary color. This disc, another matter. The advantages resulting in green. This, in turn, gives way to a ray geared to revolve at a speed one -third that from the use of color television arc obvi- of blue-violet, and the same line takes on a of the scanning disc, colors the light passing ous; but what about the difficulties? still different aspect as the darker shades through. Now the whole picture is scanned PROBLEMS of the spectrum come into prominence. while the coloring disc makes one -third of a RADIO This cycle has taken the same time as to revolution; and as each color occupies one - The first and probably most important scan one line, in ordinary television. The third the area of the disc, the entire picture problem to be solved is the same as that next trio of holes now conies into play, and is scanned in one color before the next sec- now foremost in the minds of those work- a line parallel to and just below the previ- tor has come opposite the aperture. Three ing with television: namely, the width of ous line is scanned in the three primary times the operation repeats itself, rendering channel necessary for transmission of the colors. The spiral of the disc moves on, three versions of the picture, each entirely vision current. In order to understand the until the whole of the picture has been cov- in terms of a primary color. relation between the size of the image and ered, and the rotation brings the first trio The receiver (Fig. 2) carries a tricolored (Continued on page 678)
RADIO RECEI VER 3 AMPLIFIER TO RADIO TRANSM ITTER ® SIGNAL INPUT BLUE- VIOLET GENERATOR FOR GLOW LAMP COLORING SYNCHRONIZING DISC CURRENTS. \. PHOTO- ELECTRIC / RED CELL i `--- -LENS r LENS ' GREEN LENS IMAGE COLORING 1 DISC ON SUBJECT , SPEED REDUCING SPEED REDUCING SCREEN DRIVING GEARS GEARS. MOTOR 3 TO 1 RATIO DRIVING REGULAR SCANNING DISC ARC MOTOR LIGHT SCANNING DISC -TRANSMITTER - RECEIVER
Fir/. 1. 77íe elements of the color -television transmitter. The scanning disc is run Fig. 2. The reproducing televisor also pro- at high speed. and its revolutions alternately transmit the red, green and blue of duces red, green and blue lissages, all blended the image. The cells used must resjsond'well to all three of the primary colors. bel their speed. The lamp light must be white.
www.americanradiohistory.com Radio News for January, 1929 Giving Television the "Last Touches"
A Consideration of the Practical Problems which Beset the Perfectors of an Art Whose Theory Seems Simple Enough
By C. P. Mason
TI1E noteworthy success -speaking much must be learned and put in practice, relatively -which was attained in the in order to make it feasible. demonstrations of television by various systems in the past few PROBLEMS OF FREQUENCY months has been heralded throughout the world as a sure forerunner of To increase our television images in size the immediate introduction of tele- or fineness, we must have special channels vision into the home, as well as its em- for transmitting the corresponding im- ployment for wholesale public entertain- pulses: if we are to depend on radio broad- ment. A press dispatch quotes an unofficial casting instead of multiple -wire systems expression of the Bureau of Standards, to (as we must to make television available in the effect that television "is no longer a every home) it will be necessary to have If a 48-hole disc is used at the transmitter and bands question of radio, but one only of optics." a 24 -hole disc, revolving at the same speed, of frequencies, allotted for the pur- It is quite probable, however, that consider- at the receiver, we shall split the reproduced pose. We must have receiving apparatus image somewhat in manner. able work will be done along both lines this capable of being tuned with the utmost before the baseball fan settles back into precision, and amplifiers capable of step- his armchair to watch the World Series ping up irregularly- fluctuating signals with the idea is apparent at a glance. In another the highest degree of uniformity. shown on the screen of his parlor televisor. nine, undoubtedly, it could be determined 'l'here is a popular tendency to regard It is possible that the system of television by careful study. The hundredth case is transmission finally developed will require treat inventions as the work of an inspired one of merit, perhaps; but the labor of re- genius, and to imagine that "only the first n frequency which is the speed of scanning ducing it to a working basis is the true the picture; in other words, the image fre- step counts." The reader's fancy is caught "invention." There are, of course, men by stories in the schoolbooks, of Newton quency will be the carrier frequency itself. who have the ability to make all the neces- To explain this expression: as radio op- aroused by the apple falling on his head, sary calculations of a new invention, with- and Watt observing the lid of the teakettle. eration is carried on at present, an arbi- out the capital at hand to put it into actual trarily- designated carrier frequency is gen- Of the laborious calculations and trials operation; and such men are perforce which intervened between these boyish erated at a broadcast station. This fre- necessitated to interest prospective associ- quency is modulated by the irregular speculations and the demonstration of the ates in the development of their work. the opera- interruptions of the impulses from the law of universal gravitation, or However, the high cost of inventing is not tion of the double-acting steam engine, photoelectric cell which is responding to the most formidable obstacle to the garret the alternations of light and darkness ob- there is no room in the text books to tell, inventor -it is the fact that the simple ideas and there is none here. But it is beyond tained by scanning the image. The result are already familiar to men of technical is a modulated wave which causes either doubt that many mute, inglorious Newtons education and he must, therefore, first edu- and Watts indulged in the same first specu- odd noises in a loud speaker, or an image cate himself to the general level of modern in a television receiver operated in syn- lations, but slid not "follow through." science and then specialize in his line of It is a common thing for a correspondent chronism with the transmitter. Held down endeavor. by the "traffic rules" of radio, the television to write to the editor of Rio NEWS and It is true also that a principle may be say: "Here is an idea which may be of exceedingly simple, and yet the development some value. I have not the time nor the of technique sufficient to put it in operation resources to work it out in detail; but if a very slow and tedious process. The idea MOVABLE you will do so, we will divide the credit of breech -loading guns occurred almost LAMP BOX and the profits of the invention." All edi- simultaneously with the invention of can- tors, of scientific or technical magazines, non; Christopher Columbus had cannon that and all well -known inventors have had the loaded from the breech. Yet it took about i same experience. In at least ninety cases four hundred years for mechanical tech- out of a hundred, the impracticability of nique to reach a stage where it made the ..a_, -A- _ , advantages of the breech- loader over the ql l,t muzzle -loader in every way apparent. Hertz L_ __ worked with the short waves when he dis- -T-J covered radio forty years ago; but the \ short waves are just coming into their own. So, if it is to be five years, or ten, . 1 t? I'.i before radiovision reaches the stage of prac- ticability pictured on our recent covers, the VI J LEADS TO delay will be clue only to the work of prac- LAMP -" tical development of the details which may a % Y/// seem so unimportant, compared with funda- CROSS SECTION // /// //// /O/ // mental principles, but which are essential OF BOX '--*- iil S
to its successful operation. I I 0 POSITION We have seen television progress to a OF I stage where an image three feet square DISC I I has been produced, but coarse in detail; l I we can obtain smoothness of the picture FIG.2 only by reducing it. To say that we have I I FIG.3. © I LAMP only to construct apparatus making larger cell receives the same amount The photoelectric is of light through, the hole whether it is scan - pictures in more detail something like ning the triangle A or the oblong B, and does saying that we have airplanes which can go :h detachable unit containing a neon lamp will not discriminate as to the shape. The slot nearly three hundred miles an hour-why nive us the ability to scan the received image E would cause a more accurate response, but not make them go ten thousand miles an in several :nays. By applying it to the other would require both more light and a higher side of the disc, the apparent direction of the frequency of transmission. hour? Doubtless, it is not impossible: but rotation might be easily reversed.
www.americanradiohistory.com Radio Nees for January, 1929 635 half -tone pictures broadcaster may send out only images 34,560 cycles, or even more) regardless of the process of making - detached elements. We may even sup- which keep within his "channel :" he must whether or not the image is fine or coarse. into of more than 5,000 The frequency of a circuit determines its pose this operation to be performed, without not introduce a note propor- broadcast band; on the short speed of response; the less inductance and a screen, electrically, by suitably cycles into the of oscillating current. is given more latitude, but the capacity it contains, the higher its fre- tioning the amplitude waves, he perhaps, the television highest frequency yet allotted, whether used quency, and the less the lag in registering In this manner, impulses of a large detailed image might or not, is 100,000 cycles. each impulse. within a narrow band, even Now, let us consider the case of a tele- Let us look at Fig. 2. The circles shown be confined frequency would be far from vision transmission which is to enable us at A indicate what happens when a round though their a black that of the oscillating circuit on which they to watch an athletic event, a pageant, the hole in a scanning disc passes over black would be based. But the receivers of today take -off of a world flight, etc. A 48-line triangle; those at B the effect of a and such complex image gives us little more than a head; rectangle of similar area. (It will be noted cannot amplify separate suppose we set the requirements of our that the photoelectric cell "sees" the hole impulses. television image for outdoor events at 250 as a unit, depending on the amount of light it. lines by 350. We are to take pictures in reflected through it; not the shape inside PROBLEMS OF SCANNING -four This would be true, even if the scanning color, or at very high speed. Twenty Yet, even after the radio problems had pictures a second, eight in each color, are disc were stopped; and the cell too has a "persistence of vision," though trilling corn - been solved, we would be faced with the needed for persistence of sharp vision. which the Bureau pared with ours.) The hole does not stop optical problems of The image -frequency for which we must - we are compelled keeps on going-and in the time this speaks. In this respect, it of mechanism aperture takes to cover its own width, the to choose between simplicity and exactness of reproduction. current in the circuit of the flash lamp and the size Most of our readers can readily point out 46 -OLE DISC at the receiver must fall till the lamp goes EXAGGERATED) disc, (CURVE nearly out, if the television screen is to the inherent defects of the scanning and many, no doubt, can suggest mechani- ONE INCH the presence of a dark spot. If we 1 ,6' record ,o.li :L4oi o.iG increase the sharpness of the image by cal and optical arrangements more suitable I of resolving and analyzing a for the purpose h I I narrowing the slot as at E, we must double 1 1 1 these re- the illumination of the object and double images. The only trouble is that ¡I? apparatus. (It will quire highly-skilled mechanics with pre- I the frequency of our I - I I1 i cision instruments to make the parts and il 0., ¡ ,¡ be noted that, when it is said above that I can set up - the transmitter and the receiver must rec- assemble them; while anyone il receiver will function after a 1' in the same time, the same a disc that 4-18'37=-->f ord an impulse length of time is meant. Though, to human fashion. As John L. Baird has observed, 7.'70 in canny Scots manner, "A hole is cheaper A CEN66TER senses, transmitter and receiver are acting 48-HOLE instantaneously; when their functioning is than a lens." FIG.4 CYLINDER timed in terms of radio frequencies, there First of all, the disc does not scan the its holes are The scanning disc has a curved, tapering frame is a lag in every circuit through which image in straight lines and, if which can be made square only by altering action is transferred, as well as in the set at equal angles apart, the image must the spacing of the holes. Though the cylinder "ether" through which the waves travel.) narrow toward the bottom. This, however, scans horicontally, it spreads the image sideways. It seems doubtful whether any system of is not vital, especially as the image will be televising a ball game will permit us to true to the one at the transmitter, if the prepare is 2,100,000 cycles, or 2100 kilocy- follow the ball through the air. scanning apparatus at both ends covers eles-a high radio frequency in itself. This Now, if our image is composed of solid corresponding portions of the images in the corresponds to a wavelength of less than dark niasses, the fundamental image -fre- same order and at corresponding instances. 143 meters. If we should attempt to quency of which we have spoken will not If we substitute a cylinder for the disc, we modulate a higher frequency -say 20 -meter be created by the alternations of light and obtain lines which cross the image parallel waves -with such an image frequency, no darkness; but it would be, if the image to its top and bottom, but the image tends devisable circuit could be tuned anywhere scanned were broken up by a screen -as in to be out of proportion at both sides. This near to the carrier wave and to both side - bands at once. But we might broadcast the image frequency itself as an interrupted continous wave. Whether (the interruption TELEVISION SCREEN being of a supersonic or super -audio fre- LAMP quency, on a picture taken with such a speed as this) it would be possible to modulate the wave with an audible pro- doing violence to either, gram also, without DOUBLE -MIRROR / and to unscramble them at the other end, ASSEMBLY GEARED TO / is a delicate problem. Perhaps it is not ROTATE AT DESIRED impossible of solution. SPEED PATH A PICTURE THE DETAILS OF OF RAY It should be pointed out that, in the present system of television modulation, the carrier is not modulated at any definite frequency. Each image impresses its own DRUM OF the wave. For in- PLANE characteristics upon MIRRORS RIM stance, take the St. Andrew's cross shown spot ONE in Fig. 1 at A. Each time the scanning REVOLUTION the cross, the photo- LIGHT BAND passes over one arm of TO EACH PROM TELEVISION electric current drops; each .time it emerges IMAGE. LAMP. again upon the white background, the cur- SECTION OF rent rises; but even with a 48 -hole disc and OHOLES IN SCANNING DISC. CIRCULAR say, 1 /15th -second images, the current B ARRANGE-" SPIRAL) would drop and rise again only about 1150 MENT (NOT times a second. With a single irregular © black mass in the center of the screen, the FIG.S. rate of interruption would fall to about the whole light from half this. In A we see indicated a "plano- cylindrical" lens which .rill concentrate a a mirror-drum, which causes out here the fre- lamp's plate on the path of a circular row of holes. At B is indicated It should be pointed on the next page. At C we have a suggested an image at a every spot to sweep a different path; one is pictured quency required to produce arranacment by which universal reception might be obtained; as the number of mirrors is increased, given rate of speed should remain the same of course, and the number of holes, distortion will be reduced. One of the problems in a cabinet "camera" and reproducer. (for a speed such as that above, about receiver ,must be the difference in the angles of projection between
www.americanradiohistory.com 636 Radio News for January, 1929
point (Fig. 4 at B) will be brought up we consider the effort needed "to reverse and which is caused to sweep over the again a little later on, however, to show the direction of rotation of the disc, and entire image. This principle is used in that is it not so important as it may seem. also remove the disc from the shaft and the Belin and the Alexanderson systems, Also, there is lack of uniformity in the turn it around with the other side out," and is evidently very effective to cover a various scanning systems employed, as re- it might seem somewhat simpler to trans- large area. The mirror-drum used, however, gards the "resolution" or "analysis" of the pose the positions of the neon lamp and must be made with great precision, and images; and this presents an annoying the viewing hood to the opposite sides will therefore be too expensive in manu- problem to the experimenter, some of the of the disc. facture to recommend itself for individual implications of which have been discussed While American pictures, as a rule, have use. It will find its place in theatres, etc. in our November issue (Page 429). For been scanned from side to side, the illus- The practicability of controlling several the present, it is possible that there may trations and descriptions in foreign maga- light-spots at once makes it possible to be some standardization-on a 48-line disc, zines indicate that the top -to- bottom present very large moving images, if suit- for example-for broadcast experiments; method is more in favor there. Let us able channels of transmission can be ob- but the limitations of this method show suppose our television disc and motor en- tained. (See Fig. A., below.) clearly that it will not be the final form closed in a cabinet with four cut -outs, so We may imagine a device not dissimilar, used in radiovision. And, if the frequency that we can apply the detachable lamp but somewhat simplified, in the form of used in transmitting an image and the fre- and hood at top, bottom, or either side a flanged wheel, with a rim which passes quency with which it is scanned are to bear at will.. (See Fig. 3) We can have our before the neon lamp. The rim is per- a close relation, as suggested above, then option of scanning the picture in any direc- forated, not spirally, but in a circle, with each television broadcaster will have to tion; and, if our lamp and hood can also holes which keep within the narrow width employ a slightly- different system. How be placed on the other side of the cabinet, of a beam of light concentrated on them may this confusion be overcome? we can produce the effect of reversing the by a lens which is cylindrical instead of image. If we can rotate the lamp assembly spherical in its curvature (like some reading PROBLEMS OF ADJUSTMENT around the edge of the disc -and any me- glasses now available, which magnify a line chanic will see how this could be done of type only in the direction of its height Let us consider some -we of the present dif- can produce any adjustment we like. This and not from side to side. (See Fig. 5A.) ferences. we have If a 48 -hole disc and a method of keeping the picture "in frame" Opposite each hole is its own mirror, 24 -hole disc, as in Fig. 1, and revolve the will have some advantages, as well as the formed by cutting into the flange a groove, first as a scanner (seen at A) at the disadvantages of more complicated con- with a lathe tool which continually changes transmitter, and the other before the lamp struction. its angle through the at proper number of the reproducer, we shall produce there degrees. From the bright surface of the a peculiar effect, as at B. (Incidentally, PROBLEMS OF LIGHT bottom of the groove, each successive spot this may give an opportunity to the experi- of the image is reflected upon a screen. menter who has one of the 24 -hole discs In all the popular systems of television It may be noted that the ordinary forni described in our October issue a chance as vet described, one great defect has been of glass mirror is not well suited for work to make a test on one of the 48 -hole trans- the limited amount of light available at of such precision, because it offers two missions. It may be possible, with the aid the receiver. One 2304th part of the light reflecting surfaces, one in front and one of a card held to the nose, to divide the from one neon lamp, not brilliant at best, behind, and creates two parallel images. two halves of the image, one to the right is little enough to keep an image illu- The mirror, to throw a small spot of light eye and the other to the left, to get an minated. We may, of course, construct with great speed and precision, should have effect akin to the "stereoscopic" one des- larger lamps, but these involve the use of a polished silver presumably cribed surface- in our November issue, on page 418. larger discs. A smaller disc may be used, treated against tarnishing. Owing, however, to the sharp curve of the by concentrating the light of one or more With this system, we can greatly spiral increase when the disc has so few holes, the lamps upon it with lenses; but we must the amount of light available from a given two images cannot be expected to coincide then magnify the image again, and this tube, though not as much as exactly. by using the Yet we may see the possibility dims it. There is no multiplication of light drum of mirrors. But our flanged of disc transmitting images to be reconstituted energy, any more than of mechanical en- will be still quite expensive, and not suited in a different order by other systems of ergy, through arrangements of apparatus. for use on transmissions of varying com- scanning.) However, we are not bound to let the plexity and speeds. Let us see if we can The effects of reversing the motion of the unused light go to waste. We may adopt devise a universal system of reception in disc, or the direction of its spiral, have the system of a single light -spot, into which small compass. been described in the same issue. Yet, when is concentrated all the energy of a lamp, PROBLEMS OF SYNCHRONISM We have, as before, a revolving disc pierced with a circle of small holes, on each of which is concentrated, when it passes over its scanning range, the full light of the television lamp, so far as may be done. The smaller the angle through which the hole moves, the more the con- centration of light and the straighter the line which it draws across the image. Behind the disc is a double convex mir- ror -one composed of two identical reflec- tors of large curvature, fastened back to back, revolving steadily and nearly at right angles to the disc. The speeds of the disc and mirror shafts have a variable ratio. (Fig. 5C). The light from the successive holes in the disc passes across the mirror, each casting upon it a thread of light which is reflected to the televisor screen and appears magnified. Each successive hole casts its rays upon the mirror at a varying angle, and consequently follows a different track across the screen. When one image has been scanned, the mirror has turned half -way round, and the mirror on its back commences the production of the following image. It should be noted that the mirrors will Fig. A Dr. 'Caroller, one of the world's leading television experts, with the "mirrordntm" of the receiving apparatus which he exhibited at the Berlin Radio Fair. have to rotate past their junction at the Q Underwood & Underwood (Continued on page 681)
www.americanradiohistory.com Radio News for January, 1929 637
Press dispatches re- port that Philo T. Farnsworth of San Francisco has made a demonstration of a television system which employs no machinery. RADIO News has been unable to obtain any details by direct in. gniry, but these illus- trations have been re- leased, indicating that a cathode -ray system is employed, on a prin- ciple like that de- scribed in RADIO NEWS for July, 1928 (page 22). At the upper left, Mr. Farnsworth is shown with his "camera" at the trans- mitter. At the upper right, the receiver; Mr. Farnsworth holds a "Braun tube." ©P & A Photos.
alb, ï iint IIII- WI
The three lower photos illustrate the Mihaly television apparatus exhibited at Berlin. In the right center, the receiver; the box, 10 s 12 inches, contains a horizontal scarring disc and a special "Wolfram" (tngsten) tele- vision lamp which is the distinctive feature. The construction is said to be very inex- pensive. Center left, the transmitter with its horizontal disc and photoelectric cell in the upper compartment; light -source and lens above. Lower right, the Latour wheel which syn- chronizes the system. i©. Underwood and Underwood
www.americanradiohistory.com 638 Radio News for January, 1929 Some "Foolish" Questions and Their Answers Simple Things About Radio That Do Not Puzzle You, Kind Reader, But May Prove Stumbling Blocks for Many Beginners By H. M. Bayer
T,IE story is told of a young lady who In all cases the questioner is to be com- transmitter. Therefore, to eliminate phoned the radio static editor of her local plimented on his admission of pardonable would mean the elimination of the radio paper and seriously inquired where ignorance and his desire to learn. He is the signal as well. she could purchase some new wave- person who actually learns; wherein the One of the numerous forms of apparatus lengths with which to replenish her radio "know -it-all" is compelled to wave aside as designed to diminish receiver. static is an "acoustical Upon questioning leer, the aston- trivial those questions that baffle him. It is chamber" or sounding-box, ished editor coupled to a was told a friend had informed well to remember that there is no such thing horn unit and so designed the that it passes young lady that her particular type of as a "silly" question in connection with any sound waves only of a frequency receiver occasionally ran or tone to out of wavelengths science. which it is adjusted. For example, if a and would therefore require recharging. On that basis there have been collected signal of 500-cycle sound waves is being re- The above, you will probably say, was a for this article a number of radio queries, ceived, the acoustical chamber is adjusted mighty silly question; but, as a matter of many of which a radio "expert" might con- to pass just fact, that frequency and no other; it was perfectly logical - logical for sider too "foolish" to explain; when in real- static of a lower frequency, the reason or any other that to this young lady radio is ity they comprise a goodly share of the very signal not of that frequency which as unknown to the a subject as geology may be essence of fundamental radio. They have chamber is tuned, will not be heard to any to a good many radio fans. Furthermore, been chosen because of the frequency with annoying degree. The disadvantages, how- in a science such as radio, there is no such which they are asked and, also, because ever, of this system are obvious, so far as thing as a "silly" question. All questions, their answers will enlighten the beginner as broadcast reception is concerned; but it is regardless of the manner with which they to many of the basic fundamentals of radio of value to the telegrapher. are put, may be answered to the educational which should be absorbed before any at- "Atmospherics" (static) in the temperate advantage of the questioner. Just how and tempt is made to enter into the construc- zones are most pronounced during the sum- h}- whom these questions are classified as tional field. mer months, when electrical storms are more "silly" may be explained by the reply of Mr. WHAT IS STATIC prevalent than at any other period Brown, a builder ,of during four radio sets, who, the year. For this reason radio reception in when asked by Mr. Smith what radio is, Question: "How can I eliminate static ?" the tropical zone is indeed a matter of en- replied: "Why, is radio er-er, why radio Answer: Up to the present writing sci- durance, except on the ultra -short waves. is er -now let me see -m -urn -m-radio is- ence lias devised nothing that will eliminate Static dining the winter months is a com- er -r good -why, heavens, man, you don't static. There is no such thing, and, to all parative rarity, and is often confused with mean to tell me you don't know what radio appearances, will not be for some time, a power-line noises, near is!" -by trolleys, power- static eliminator. Many devices have been transformer leaks, adjacent electric motors, The key to the above situation is perfectly designed to diminish the static nuisance, but electrical vibrators, X -ray machines and mi- obvious. To the learned Mr. Brown, Smith's these have been either too complicated or merous other sources of what is generally question was just "too silly for words," for too uncertain in their action to be of high known as man -made static. the simple reason that it stumped him! It commercial practicability. Static may be is very evident that, had he been capable of classified, loosely, as Nature's Radio Wave, WHAT ARE KILOCYCLES? putting forth a plausible answer, he would and, as such, it passes through the radio have done so, if only for the purpose of im- receiver in identically the same manner as a Question: "lrhat is the difference between pressing his friend with his erudition. radio wave emanating from a broadcast kilocycles and meters in discussing the ware - length of a station? What relation have they to each other?" Ya, it is not necessary to open the window to let in radio waves; they Answer: This subject is one of the larg- pass through stone, brick, wood and est thorns in the listener's side. It has a glass. But, on the other hand, meta!, knack of taking on a deeper tinge of mys- such as structural steel, deflects them tery with each new attempt explanation and often causes "freaks" of recep- at tion, especially in cities. and yet, like most problems, is exceedingly simple once the idea is grasped. Wavelength has nothing to do with the power or the transmitting range of a broad- cast station. Radio waves are in some ways similar to water or sound waves, though radio waves cannot be seen like a water wave, and sound waves are likewise invis- ible; yet it is known that a tuning -fork when struck sends out waves of sound, which go out into the air in all directions. Likewise, an electric current flowing in a wire causes an alternating or changing elec- trical pressure in the "ether" about the wire, just as a piano wire when struck causes a to -and -fro motion of the air. A complete pair of alternations (see Fig. 1) is called a cycle and the number of these cycles per second is known as the frequency of the wave. The reader must not get the idea that this picture of a radio "wave" represents any actual motion in the air about him. It is an engineer's way of drawing a diagram showing how the voltage changes at points in the path of a wave. The "wave" causes
www.americanradiohistory.com 639 1929 . Radio ATOWS for January, a dynamo (a "motor -generator" com- and fall as shown at the human eye, which responds to the waves drives the voltage to rise In the RADIO NEWS Laboratories, this causes a very of light, and of that which is sensitive to bination). points in its path; and obtain alternating current, a motor -gen- aerial, producing the the long waves of radio.) to slight current in your is used which runs from the direct - by your set. erator "signal" received WALLS DO NOT CONFINE RADIO supply furnished in parts may be one of current lighting 'l'he scale of the diagram room number of crests Question: "Must the window of the of New York City. time; and in that case, the open who does not care to representing onesec- in which the receiver is located be kept The fan, however, of the wave on a line is being must use batteries, at distance between when an indoor or loop antenna go to this expense ond is the frequency. The least to supply such plate current as his re- the nearest crests is one "cycle." used ?" Answer: Radio receivers have been ceiver requires at more than 90 volts. He But the rise and fall of voltage caused questioners sug- at slightly dif- placed in mines, and even in steel vaults, cannot, as many ingenious by the "wave" takes place one tap from the 110 -volt D. C. the transmitter. All and reception was successfully accomplished gested, put ferent distances from can and do penetrate line in series with another to make 220 volts; indicate that it takes the wave there. Radio waves experiments in their travels through space, a short -circuit would be the result. to go 186,000 miles, in round mountains one second certainly can penetrate the walls or 300,000,000 meters. For that and most numbers, There may be loss of energy, "FILAMENT EMISSION" reason we often divide the speed of "propa- of a home. due to the absorptive qualities of the metal gation" of the wave by its frequency and "How is it possible for a radio used in the construction of the building; but, Question: arrive at a (more or less) exact figure which brilliantly, and yet be `dead' course, this will not be noticed by the tube to light we call the "wavelength." If we have a suf- of set?" in an average home. An "absorp- for use in a radio ficiently long wire stretched in the direction listener are a number of causes and -grounding" system is put to use in Answer: There from which the signal is coming, we may ap- tion- of a vacuum tube to func- cases where delicate experiments re- for the refusal ply methods of measurement, showing the many filament still glows with nor- absolute shielding from any external tion while its "wavelength" to be the distance between two quire One of these is the short - tends electrical disturbances except that of the mal brilliancy. points on the wire at which the wave circuiting (or making a contact not called for in the design of the tube) of two in- ternal elements; as between the plate and Fig. 1 the grid or the grid and the filament. In TRAVELLED IN ONE SECOND - -.- DISTANCE If we divide the speed of the latter case the filament usually is tie - 1 I 1 radio by the "frequency" after the current is 1 stroyed immediately 1 of a wave, we get the 1 1. turned on; in the former, the tube will re- "wavelength." This, how- will prob- ever, is a diagram of an fuse to function, yet the filament I I electrical condition, and ably last its normal life. $ I not a picture of any The most prevalent tube ailment, however, ONE WAVE 1 "waves" that really exist sets in after a tube has been in service for CYCLE . ALENGTH in the air. ;f some time, usually a year. At this time a marked weakening of signal strength, in- DX with the same ease as signal to be received. In this case, the room ability to get to cause a similar voltage in the wire. With was new, and perhaps some in which the receiver is located is com- when the set waves such as broadcast transmitters send of distortion, may take place. The with short- pletely shielded by means of copper screen- degree out, this is rather difficult; but cause of this is the burning down of the fila- wave apparatus, such as amateurs use, this ing placed on the walls, the ceiling and the connected ment to a point where the amount of "elec- experiment is easily performed. (A descrip- floor. The six screens are then to complete providing a trons" it gives off, when heated, tion of such an experiment, by John L. Rein - together and grounded, thus circuit, is con- unwanted impulses are the "plate" or "B" battery artz, appeared in RADIO NEws for October, system whereby the with a resultant drop in the screens and directed to the siderably lessened, l92î.) picked up by operation. As the tube depends ground before they can be picked up by the efficiency of FIGURING TILE FREQUENCY the filament's discharge of electrons coils in the receiver. The antenna used with upon '191e "wavelength" of radio is therefore a the latter, of course, is of the external type. which always comes to the same fig- number IT CAN'T BE DONE! ure when multiplied by the "frequency "; that unchanging figure is the speed of the Question: "How can I arrange a trans- "wave," which is the same as the speed of former to step up 110 -volt direct current for light. The speed, or "velocity," of the wave my "B" supply ?" is 300,000 "kilometers" a second ( "kilo- Answer: You can't! The action of the meter" is short for a thousand meters, just transformer, by which voltage is increased as "kilocycle" is short for a thousand cy- or reduced, depends upon the alternation or, cles). Then: at least, pulsation of the current. Steady, The frequency (kilocycles) times the direct current will not operate a trans- wavelength (meters) equals the velocity of former. radio waves (300,000 kilometers) ; 600 kilo- It would be possible, with the aid of large cycles is the figure you find in broadcast condensers, to build an apparatus resem- stations lists opposite 500 meters, and their bling the "hydraulic ram" to cause the nec- product equals 300,000. essary pulsation in a supply of direct cur- The velocity of light divided by the kilo- rent; but it would be too expensive and cycles equals the meters: 1,250 kilocycles, uneconomical for use. It is, however, prac- therefore, must be 240 meters, because 1,250 ticable to run a direct- current motor which goes into 300,000 just 240 times. The velocity of light divided by the meters equals the kilocycles; to find the frequency of a 200-meter wave, we divide 300,000 by 200. The answer is 1,500 kilocycles, of course. (We may note here that heat, light and X -rays are also electro- magnetic effects, like radio; but their waves are almost incon- ceivably shorter, and their frequency is in- comparably higher. The wavelength of ordinary yellow light is about one two -mil- lionth of a meter or one forty- three -thou- sandth of an inch, and its frequency over 512,500,000,000,000 cycles or half a trillion kilocycles. It will be seen how different DON'T plug an A.C. radio device into a D.C. socket must be the tuning of apparatus, such as -that is, unless you wain to buy a new one, anyway.
www.americanradiohistory.com 640 Radio \'c7.'s for January, 1929
for its operation, the manufacturers coat the filaments with an "element" known as thorium which aids in giving off a stream of electrons sufficient for the successful opera- tion of the tube. After the tube's normal service the thor- ium is fairly well burned off, thus decreasing the number of electrons flowing from the filament to the plate. It is this weakening of the filament's operating efficiency which causes the unsatisfactory performance of the set. At times this condition will come upon a comparatively new tube -a fault known as "paralysis." To correct this, and also the weakening in old tubes, we may employ a process known as "rejuvenation" or making youthful again. This rejuvenation is carried out on the theory that there is additional thorium dis- tributed through the metal of the filament; and it is often possible to form a new sur- face layer from this reserve supply, so that the tube will operate as well as when new. The process has proved itself fairly success- ful in the majority of the cases when rightly carried out. It consists of two successive treatments known as "flashing" and "bak- ing." In the first, a high voltage (much Fig. 2 higher than the normal) is applied to the The respective positions of audio and radio frequencies in the scale are shown above, though filament for only a short and definite period not on an arithmetical basis.. The frequencies of A.C. machinery arc indicated by a ", those of time, usually specified by the manufac- of a superheterodyne's intermediate stages by LF. The carrying power of electrical frequencies, turer. After this the tube is "baked" by ap- to a certain limit, at least, increases as the frequency increases-and the wavelength shortens. plying the normal heating voltage to the filament for a definite period of time. While fled to very high power, sometimes causes performing raising the load from its original level, we these operations no "plate," or the programs to be heard in telephones near must tunnel the mountaili. "B," voltage is used. This corresponds by, but it would not be practicable to have in a way to the use of telephone wires to reception of RADIO AND AUDIO FREQUENCIES this kind at any great distance, carry sounds at the original audio (voice or and no sharp tuning would be possible. music) frequency. Question: "I f radio wares are always in It is expensive and lim- 'l'he audio -frequency currents can be car- ited in scope. the air, why can't I hook a pair of phones ried a long distance over wires; but even If we are to at aerial and hear the signals?" content with a moderate eleva- with the aid of these, for very distant con- tion, we may send the freight over Answer: Because the radio signal is sent a railroad versation, it is desirable to use "carrier- at the lowest height through space on a "carrier- wave" whose of ground we can find currents" (of very low radio frequencies, in the range. This may pitch is from ten to a thousand times too be taken to corre- as explained in the article "Wired Wire- spond to a "wired -wireless" high to be heard by our ears. This is done carrier fre- less," in October RADIO NEws). quency, because "audio- frequeucg" currents -electric which is a very low radio frequency; We cannot hear even "audio- frequency" but it also requires a continuous currents alternating the same line of ap- at rapidity as currents directly; it is necessary to have paratus from the the vibrations of the which point of transmission to air make sounds telephones, a loud speaker, or some such de- the point of reception. that we can hear -do not carry well over vice, to turn the electrical into mechanical Or we may put the goods in question on long distances; and if they did, a radio re- vibrations which can affect our ears. an airplane and fly over the ceiver would pick up all the radio conversa- mountains. This We could not hear radio- frequency vibra- corresponds to our broadcast tion in the world at the same time. radio fre- tions if the telephone were connected in a quency. The The use of "radio- frequency" farther we have to go, prob- carrier radio- frequency (R. F.) circuit of sufficient ably, the higher it will waves makes it possible to select one be desirable to fly. radio power; first, because the diaphragm of the But, whether by the second method message out of the thousands in the air, and or the telephone and its coils are not designed for third method, what goes up also to transmit the signals with low power. must come vibration at such high frequencies (100,000 down. So it is with the radio The "modulator" of a broadcast station, signal, which to 100,000,000, and more, times a second). must be "detected " word, where audio -frequency currents are ampli- -in a brought Secondly, our ears cannot hear vibrations of down from the high radio frequency to the more than 10,000 to 20,000 times a second, original audio frequency. no matter how powerful they are; they do not produce a sensation of sound. HOW MUCH WIRE ON A COIL? Question. "How many inches of wire do WHY "R. F." AND "A. F." I wind on a coil to add another meter of Every radio receiver comprises three warelengthP' parts, more or less complicated; an R.F. Answer: This is a very proper question, end, in which the currents alternate and which constructors often ask. To answer it flow at the same frequency at which they here, however, is impracticable. The rules are picked up by the antenna; a detector, for calculating the wavelength of a coil from to remove the high- frequency (R. F.) "com- its size, turns, etc., are so complicated that ponent" of the current, which was put in at ordinary arithmetic is not enough for work- the transmitting station; and an audio-fre- ing them out. A high degree of engineering quency (A. F.) end, in which the currents education is necessary. For that reason, it are again at a frequency low enough to is easier to find out by experiment what re- produce sounds in the phones or speaker. sults are obtained with a coil of a given size In some receivers there are one or more "in- and a condenser of a given size. The coil termediate frequencies" -but these are also sizes which are given for a given condenser radio frequencies. to cover a given range of frequencies (and, Fig. 2 indicates graphically a comparison of course, the corresponding wavelengths) which is not exact, but which gives an idea will be suitable for use in another circuit of the use of the respective frequencies. We with a condenser of the same size. Such wish to send a shipment from a station on figures are given from time to time in RADIO one side of a mountain range a Even if the phones could vibrate with radio to station NEWS (see, for instance, page 1255 of the wares, the frequency is far too high to hear. on the other. If we wish to do so without (Continued on page 676)
www.americanradiohistory.com Radio News for January, 1929 641 The Dark Side of Radio By Dorothy Gernsback
THE spirit of Christmas had even de- to his landlord, "ail craves to make speech Part way clown the stairs he heard a scended upon the Soakem Radio with yuh." voice of exquisite sweetness which seemed Company, and in their extreme "By which yuh means yuh is cravin' a to meet him, yet no one was to be seen. though somewhat frugal magnanim- favah from off mall hands," hisses the land- Suddenly, a dark figure approached him ity, they had made at least one poor soul lord. and in a sweet womanly voice called out, happy. Ulysses Grant Rasby, general por- "Not from your hands, Small Snigsbie, "Ulysses Grant Rasby, is dat you, yoself ter and all- around man for the Soakem foil anything condn' from off'n yoh hands (lot I makes speech with, or is you some- Company, had been worshiping, from afar um dirt black, but what ah does need is yoh body else besides yo'self ?" and from every other angle of proximity, a roof fob malt aerial, as der calls it." Coining doser, Ulysses espied a figure and long discarded and neglected shop -worn "Niggah, yoh speaks voids dat means recognized it at once. "Sambo Brown, you crystal outfit, which he secretly hoped would nothin' to dis heap baby. Yoh aeryial can silo' did fool me fo' a minute. And what be his some day. True, this outfit had all get de air for all ah cares, but not dis roof old tricks are you up to, anyway? The next the earmarks of a "has -been," with its cat - heah dat holds mah morgages. And ah thing yo' know, Mr. Keith gwine give yo' whisker somewhat shrivelled from long speaks finality when Ah says NO with a a million col' cash fo' your dis hear ventri- usage, and the crystal almost worn down to capital W." liloquism act, or whatever yo' gwine calls a grain. That he had hoped to resuscitate From which conversation von can glean it." it from its present derelict state when op- the character of Landlord Small Snigsbie. "I'se gwine think about yo' suggestion," portunity called can be proved by the indu- To describe him would be a waste of time parts back Sambo: "but why you groin' sion of this hope in his regular Sunday and space. He is not even worthy of de- around with a face dat looks most unnat- prayers. "O, good Lord'," he would pray, scription, so I will leave him to the imag- ural like? Maybe yo' gwine seen the fiery "You silo' can save clot from fallin' into ination of mY readers. cross of the Ku Klux. But make light of blasphemousin' hands. If Yo' is hankerin' Now Ulysses Grant Rasby is a good and it, brother Rasby, make light of it, and to do some good to dis beap baby, put Yo' timid young man when unmolested, but tells yo' friend heah what dat pallbearer kind O.K. on papa heah fo' a pospectus when his African is aroused, watch out. physiognomy is done got behind it." candidate for dis heal' set." Especially when it concerned his radio set, To which advice given gratuitously and Opportunity did knock on Christmas day, the object that caused the whites of his eyes with such wise philosophy, friend Ulysses and Ulysses was almost knocked over with to shine with a belladonna lustre. responds, and tells him all about Landlord surprise and delight, when one of the head Then again, another very good reason for Snigsbie and his mean disposition. I.et us Soakems invited him to cast his eye in the his desire to rig up his radio set without leave our friends to their own wise counsel, direction of the abandoned pile of scorned further delay, and a very good reason at and wander back to Landlord Snigsbie. and antiquated outfits. To Ulysses this was that, was that Nitrate Eliza Pepp of the To proceed: Landlord Snigsbie had the first approach to heaven, and it didn't "Lookin' Wild" company was to sing her parted most sorrowfully only a few days take him long to get there; for with one song hit on the morrow into the cold, hard ago with fifty paper doubloons for a six -tube leap and bound, as they say it in stores (the ear of Station \1'ßL'\1. That this meant a Niggadyne set. You see, Nitrate Rliza "bound" should really be left out of it, for great deal to Ulysses can be only measured Pepp had smiled him into it, and he sure he got there with one leap, to be exact) he by the rapturous glances he fixed upon each did like to receive One of her smiles, provid- reached and held in his ebony hands that and every photograph of Nitrate which be- ing it didn't cost too much. Nitrate had 1recious crystal set, plus 'a pair of head- decked his room. To hear Eliza's voice presented him that day with an autographed phones, deaf in one ear and catarrhal in the meant music to his ears. No, he simply photograph of herself, because you see other, but serviceable, nevertheless. must fix up that radio. He would swallow Nitrate knew a well -filled pocketbook when If you wish to know anything further his pride, and go down again to his heart- she heard of one. To have the neighbors about Ulysses Grant ltashy, just follow less landlord with perhaps an inducement or cone in and envy his radio set would partly along to 9934 East 135th Street, climb up two, for the favor of installing the aerial. (Continued on page 684) two ramshackle flights of stairs that creak and groan with age, knock on the door and wait. If you are at all interested in our hero, you'll do this; because the knock will bring his kind but elephantine mammy to the door. She'll ask you in, wipe the dust from an almost dustless chair with her clean checkered apron, and tell you all about ber first, last and only son. She'll tell you that Ulysses spends his spare time a- riggin' up all kinds of bells that bring out funny and spooky noises, that there isn't a thing he couldn't make out of a few screws or old tin cans. She'll tell you perhaps that there's not another boy as good as hers, that every cent of his fifteen dollars per goes to her, and so forth. To come back to Ulysses Grant Rasby, who had by this time arrived home in an utterly breathless state, carrying with great pride and care his precious crystal set and earphones. In the twenty -three years of his uneventful life, never before had he felt such ,joy, and it did not take him more than a second; for with three steps at a bound lie reached the ground floor of the house in which he lived. And why the ground floor, you ask. The reason is that Landlord Small Snigsbie had his bachelor quarters installed "He pulled it out bodily by its roots, there. with the entangled wires hanging 'See heah, Small Snigsbie," our hero says limp and in disgrace, and flung it through the door, followed by the loud speaker."
www.americanradiohistory.com Radio L\'MIS for January, 1929
The "Bloopless" One -Dial, Two -Tube Receiver*
THE two-tube receiver described in WHAT HAPPENS IN THE TUBE this article was designed for the radio beginner who holds in awe No. When functioning as a detector, in either the construction of vacuum -tube re- 71 a one- or a multi -tube set, the tube serves as ceivers. It will prove to him that the con- The "]3loopless" Two is a rectifier. When it serves in that capacity structional difference between a crystal re- about the simplest poss- the signals, after passing from the tuning ceiver and the set herein described is but ible set, either to build or unit and through the grid condenser, are a matter of a few additional wires to be to operate, and will not impressed upon its grid in positive and soldered and the mounting of a few more radiate. Large blueprints negative alternations. simple parts; while the same assertion holds of this set, with the list of parts While this action is going on in the grid true of the difference between a two-tube originally used, will be sent free of circuit a constant flow of electrons is leav- set and a five or six -tube set. charge, postpaid, to any of our read- ing the filament of the tube and bombard- There is nothing new in the circuit of ers applying for them on the Free ing the plate. The latter has an electrical this set; nor are any recent inventions em- Blueprint coupon which appears on attraction for the flow of electrons (which ployed in its assembly. As the title im- page 701 of this issue. Ask for Blue- are negative electricity) due to the fact plies, it is about the simplest possible two- print No. 71. that the plate is kept at a positive poten- tube set, designed solely for the benefit of tial by means of the `B" battery. For recent initiates into the radio builders' guild, this reason the positive, or "+" post of the and those who are contemplating hopefully "B" battery is always connected to the the possibilities to be worked out with the a coil of wire, or inductor (commonly, plate of the tube; either directly, when screwdriver and pliers. For the latter though inaccurately, called an "inductance ") there is another tube following it, or, as in class, especially, this little set offers an ex- with which to "load" the antenna; a vari- this case, through the headphones, or loud cellent beginning because of the theoretical able condenser to "tune" this coil, so that speaker, the other terminal of which is con- ground -work which can be obtained while stations transmitting on different wave- nected to the plate. (The readers who de- building and experimenting with this re- lengths may be "tuned in," at different sire to know more about this are recom- ceiver. It is the simplest form of vacuum - settings of the condenser dial; a grid con- mended to read "What a Radio Tube Is tube set which is fit for an experimenter's denser and a grid leak, (which are nec- and What It Does," on page 1124 of the use in ordinary broadcast reception. essary if the tube is to function as a de- April, 1928, issue of RADIO NEWS, and For a preliminary explanation, Fig. 1 tector) ; and requires also suitable batteries "What Is Detection ?" on page 1151 of the gives a schematic diagram of the simple de- and a pair of headphones to reproduce the same issue). tector circuit which is found in every vac - radio "signals" which have been made aud- This filament -to -plate flow of electrons uum -tube receiver, regardless of the com- ible by the action of the detector tube. provides a circuit which will allow an plexity of the circuit or the number of These components make up the basic unit of electric current to flow in only one direc- tubes. It is, in itself, the simplest vacuum- every radio receiver employing vacuum tion; it is this characteristic which gives tube receiver which can be assembled for tubes, and it is this unit which is so often the vacuum tube its properties as a rec- the reception of radio signals. It comprises referred to as the "heart" of the set. tifier of alternating current. The two -ele-
t ¡Ground, Aerial 4241 j IGround (Aerial i This rear view of the "Bloopless" receiver shows how simple is its Another view, from a higher angle, shows all the wiring of this construction. The coil L is home -made, the parts are few. The set; a wooden baseboard is used, saving the trouble of drilling. The addition of a. two -tube amplifier gives speaker volume. symbols are given in the diagram and parts list, page 645.
Itnnio NEWS Free Blue print .-hrtif/C Sn. 71.
www.americanradiohistory.com Radio for .11117FidìC. 643
the plate to the grid. (This is not per- The diagram given as Fig. 2 shows a petual motion; the power is supplied from simple regenerative circuit employing the AERIAL 'GRID LEAK the `B" battery or power unit). But, un- old -time "Ultra-audion" hook -up; it will be GRID CONDENSER noticed is a state TUBE less this process is checked by limiting the that the tube brought to j flow of current-either in the filament, in of oscillation simply by connecting the "fila- the grid, or in the plate-the tube will get ment" return of the inductance coil to the J) beyond the control of the grid and will plate of the tube instead of to the filament, Z variable in 0 "run away" or "race "; just as an engine as commonly done; a condenser U will when its governor is put out of com- series with this lead controls the regenera- mission. Then the tube is "oscillating" and tion. pouring power backward into the aerial, if In Fig. 3 we have a regenerative circuit it is connected to the latter, as well as employing a separate winding, the "tickler," TUNING IIII+ ahead into the audio stages, unless they con- to bring about a state of oscillation in the = CONDENSER BATTERY tain chokes to keep it back. If the tube detector. This method of obtaining re- GROUND is of res- is known as feed- FILAMENT CONTROL FIG.1 connected to an aerial suitable generation "inductive onance, it then becomes a transmitter; and back" because the energy from the plate BATTERY as such, operating on the broadcast band, circuit is returned to the grid circuit, by NON -REGENERATIVE a single one -tube set will cause disturbance virtue of the close proximity of the tickler a distance of ten or coil to the tuning or grid coil and The simplest tube circuit. It does not radiate, in broadcast receivers at plate but has little amplification or sensitivity. miles or more. the "mutual inductance" of the two wind- Regeneration, however, produces the effect ings. Quite often the tickler winding is so meat tube is used extensively for this pur- of increasing the strength of the signals by designed that its position can be varied in pose, in modern electric sets. apparently reducing the resistance of the relation to the grid coil. When provided It was Dr. Lee de Forest who discovered circuit. It also greatly increases the selec- with this mechanical means of variation, that by inserting the third element, the tivity of the circuit and makes possible the the tickler is described as loosely coupled grid, he could control this flow of current. reception of distant signals which ordinarily or variable. The grid consists of a very line However, this method of con- wire spirally arranged, with wide trolling regeneration has the dis- spaces between the turns; so that rc', `R5 advantage, for a beginner, of the electrons can pass between introducing mechanical difficult- them on their way to the plate. ies, such as the construction of a De Forest found that a negative suitable shaft and mounting de- charge on the grid reduces the vice; furthermore, this method strength of the filament -plate falls short when critical con- flow, while a positive charge tends to increase this flow; this is based on the electrical law that opposite charges attract, while like charges :1t the'left, a view of the panel of Uw two- control repel. For example, the negative "Bloopless" set. The con- electrons leaving the filament on denser Cl tunes the their way to the positive plate receiver, R5 is the neces- which is attracting them, are sary regeneration and vol- ume control. SW shuts driven back by the grid when it off the battery and 7 is is negatively charged. And, in ac- the jack for phones, which cordance with the above -men- may be used for distance work, even if as amplifier tioned law, the electrons are is added. aided on their way to the plate when the grid takes on a positive charge. It can be seen, therefore, that the grid cannot be heard with a non -regenerative re- teal is desired. Far better results have acts as a control of the current flowing ceiver. (Readers will find a more extended been obtained with a fixed tickler winding from the plate of the tube into the phones explanation in "Regeneration -What It Is employing as its means of control a variable or loud speaker. No matter how rapid and What it Does" on page 1234 of RADIO condenser. the fluctuations that are impressed on the News for May, 1928; and the articles in last Still another method of controlling a fixed grid, the plate current imitates these in month's issue, "How to Succeed in Short - tickler winding is that comprising a vari- accordance with whatever voltage varia- Wave Operation" on page 552 and "Some able high- resistor, either in series with the tions are present in the original wave from Easy Experiments with Oscillators," page tickler or shunted across it. This method the broadcast station. Furthermore, since 554, explain in what manner oscillation may has lately come into favor both with broad- a very small charge on the grid has a rela- be put to use.) cast aanil short -wave fans; for it has sta- tively large effect on the plate current, the tube amplifies the small electrical impulses which are impressed on the grid. Thus it can be seen that the tube both detects and VARIABLE TICKLER amplifies. THE OSCILLATING DETECTOR The simple one -tube receiver shown in Fig. 1 employs a non- regenerative circuit; that is, no electrical or mechanical method which would cause the detector to oscil- late has been included in the set. An ex- planation of the theory of regeneration may be a bit complicated for the average beginner; suffice to say, in brief, that "re- generation" is putting back into the grid circuit of a tube a portion of the energy in the plate circuit. But, whenever a tube REGENERATION CONDENSER is working naturally, the energy in the FIG.2 plate circuit is liberated in spurts corre- rB BATTERY FIG.3 sponding to those in the grid circuit, but greater in value. Therefore, the action of These regenerative detectors Ilse capacitive (Fig. 2) and inductive (tickler, Fig. regeneration is to build up an ever- increas- 3) regeneration control, giving great sensitivity: but, as shown, they are public ing amount of energy flowing back from nuisances. An manned R.F. stage takes away the curse.
www.americanradiohistory.com www.americanradiohistory.com Radio .\ r;. s for Juniwrv. 1929 645
flue quarter pound No. 24 D.C.C. wire for AERIAL COIL r----5. roil; hook -up wire, push -back type; FORM I 1 TICKLER screws, etc. RS The first step in building this receiver is I L I annntvvR4 to wind the coil, which is to have the pri- I6. mary, secondary and tickler windings on V2 the same "form." Two small holes are 1.1 '4. drilled in the tube about half an inch from I one end; these are to secure the terminal Y of the primary winding, and two such holes a! T^ should be drilled at each beginning and end- ing of each winding. After securing about 3I six inches of the end of the wire through 13. L the two -hole "grip," wind the primary; as z. may be seen from the drawing of the coil SECONDARY details, this winding comprises eight turns. After these have been wound evenly and JUMPERS securely, run a sufficient length of wire GROUND through the two -hole "grip;" so that con- SW "SPARE" \ i nections from the coil to the other com- POSTT - @ J ponents can be made without recourse to needless splicing. This should be done with O O O O both end% of each of the three windings; A- A+ B- 8 +45 VOLTS TOP POST OF about six inches at each winding terminal TO'B+ POST OF AUDIO TRANSFORMER will suffice for this purpose. Follow the AUDIO TRANSFORMER IF AMPLIFIER IS USED. details shown in Fig. 7 for all three wind- ings. Care should be taken, also, that the Fig. windings are wound on the form in the same The schematic diagram of the "lilaopdess" set shows the circuit in a form easy to direction; if any of the windings are re- read; many constructors prefer to build from a schematic. The resistor Itl saves versed, they will "buck" each other and making another coil. there will be no results. not to publish or give out constructional FEW PARTS REQUIRED information describing the circuit of a re- ASSEMBLY AND MOUNTING generative broadcast receiver where the One hard- rubber panel, 7 x 12 -inch; It will be noted that a two -layer winding One wooden baseboard, 111/2 x 7 x 1/2 -inch aerial is coupled to the grid of the detector is specified One variable condenser (C1) .00035 -mf; for the tickler; this construction tube, the set described in this article was is merely to save space and has nothing One variable high- resistor (R5), 0- 2000 -ohm to designed with a stage of untuned- radio- do with the electrical action of the receiver. vacuum sockets V2) L-S frequency amplification between the an- Two -tube (VI, Before mounting the coil on the baseboard, tenna and the detector tube. While the type; it will be found more convenient to place value of this extra tube as an amplifier is One filament switch (Sw), panel type; the necessary apparatus on the panel, and problemtical, it serves the purpose for One closed- circuit jack (J), (three- blade) ; then fasten the panel to the baseboard. If R3) % which it was included in the hookup; and Two filament-ballast resistors (R2, the coil were mounted first it would prove that is to prevent any "whistles," "bloops" ampere type; somewhat inconvenient to solder leads to .0005 - or "howls" from passing into the aerial One fixed (by -pass) condenser (C3), the jack, which is slipped under the tuning from the detector. Serving in this capacity inf.; condenser and behind the coil. it is referred to as actually, a "choker" One grid condenser (C2), .00025 -mf.; tube -the name being self -explanatory. One grid leak (114), 2- megohm; When fixing the coil on the baseboard, With the exception, perhaps, of the re- One antenna resistor (R1), 100,000-ohm; mount it upon two half-inch supports; in generation control, the apparatus for this Two grid -leak mountings, for antenna re- this particular set two large binding -post receiver could be assembled from the spare- sistor and grid leak; tops were used for this purpose. The same parts box of the average experienced ex- Nine binding posts, either push -type or type of "elevators" was used when mounting perimenter; even if the parts have to be spring-type. the binding -post strip, directly behind the purchased they will cost little more than a One dial, 4 -inch, bakelite; toil and at the rear edge of the baseboard. good crystal receiver. At that, each part One binding -post strip, bakelite, 9 x %- However, if the constructor desires even purchased will be an investment in future inch; more simplicity than is offered in the lay- constructional work, for the simple reason One 4 -inch length of 2 -inch bakelite tubing, out of this receiver, he may substitute spring that every part specified for this set can be for coil. -type binding posts for those spedi- used in any of the advanced five- or six - tube receivers; with the exception, of course, Fig. 7 At the right arc the neces- of the panel and baseboard. The following sary details for making BAKELITE FORM list of parts is in addition to the "acces- the coil L to be used with sories," which will be described toward the a .00035 -mf. condenser. end of this article: Follow directions care- PRIMARY fully. 8TURNS24 D.C.G. FRONT PANEL
I
SECONDARY T 65 TURPS 24 D.C.C. 4" 4"
Lm lop tsi 4 HOLES 3/6 DIA. 2 SCREW HOLES 513 -DIA TICKLER 35' TURNS 124 D.C.C. n1 5%4 6. WOUND IN 2.LAYERS
12" 2i-" COIL DETAILS Fig. 8 z Only six holes need be drilled, as shown.
www.americanradiohistory.com 646 Radio News for January, 1929 fled here, and mount them directly on the ating. When this stage is reached, turn THE ANTENNA baseboard. the tuning dial slowly until a whistle is As for the other components, the layout heard, which is the sign of a broadcast Much has been written about aerials and diagram (Fig. 6), is sufficiently explanatory station being heard when the receiver is grounds; yet, judging from many of the to indicate the manner in which they are oscillating. Tune the whistle until it is installations that are still being made, a mounted and wired. In the same diagram loudest in the phones, and then turn the hasty observer would think that no author- will be seen a jumper connecting posts Nos. knob of the regenerator until the whistle ity had ever said a word about this very 2, 3 and 4 (counting from the left) ; when disappears; then the music or voice will important part of a radio installation. It adding audio amplification for loud -speaker be heard. is here emphasized again, or yet, that the operation, a lead is run from post No. 2 to No mention has been made of dry-cell best results cannot be obtained from a re- the `B--" post of the first audio-frequency (199 -type) tubes for the reason that the ceiver unless particular care is exercised transformer, and another lead from post constructor, even though he is a beginner when erecting the aerial and making the No. 1 to the "P" post of the same trans- in radio, will eventually need a storage ground connection. (Continued on page 670) former. Binding post No. 3 is used only battery as well as the storage-battery tubes if the constructor desires to experi- (201A -type) which are specified for this ment with different "B" voltages on the set. If such are his expectations, the pur- otherwise, chase 199 BINDING POST plate of the first tube, VI; of -type tubes and the necessary TRIP JUMP AERIAL -I, ignored. dry -cells will be somewhat in the form of RS . u u . u "ACCESSORIEe a needless waste-not to mention the fact u that better results are obtained with the op - - - - one The operation of the set requires: larger tubes. However, if circumstances, TO'P -POST OF AUDIO storage or "A" battery, one 45 -volt dry - such as lack of electric power, etc., neces- TRANSFORMER IF AMPLIFIER IS USED cell or "B" battery, two 201A -type tubes, sitate the use of 199 -type tubes, all that a headset, and a suitable aerial and ground. need be done to adapt the receiver to them GROUND After these accessories have been added is to substitute the proper filament- ballast to the receiver and the filament switch is resistors for those specified and, of course, turned on, a turn of the tuning dial should employ three dry cells to light the filament bring in some signal. If nothing is heard, of the tubes in place of the storage battery. 'B BATTERY 6VOLT BATTERY 'A' turn the knob of the high -resistor R5 until The use of dry cells to light the filaments FIG.4 in the phones; of 201A -type tubes is not recommended, for a rushing sound is heard The way to hook up the "Bloopless" to the this indicates that the detector is regener- obvious reasons of economy. batteries, aerial and ground is very simple. Some Hints on the "Junk -Box" Short -Wave Receiver By Robert Hertzberg
MOST of our readers who made instruction by increasing this space, till the with a strong "plop," the operator will be "Junk -Box" short -wave receivers coupling is ineffective. The windings on able to distinguish only the squeal of the according to the description con- one set of coils examined in our laboratory carrier wave of a broadcast station; this tained in our July, 1928, number were separated fully five eighths of an squeal is the result of the carrier heterodyn- are now enjoying satisfactory-in some inch. ing or "beating" with the oscillations gen- cases, really remarkable -results from this erated in the set. By adjusting the receiver now famous little outfit. However, as might so that it is oscillating at exactly the same be expected when several thousand people frequency or wavelength as the carrier of using different parts endeavor to follow one the transmitting station, it will become pos- design, many are reporting trouble. For sible to hear the voice of the announcer, benefit we offer here a few hints which BASEBOARD although the reproduction will sound slightly their r may be of value in correcting the diffi- BRASS OR "mushy." This method of tuning is known culties. COPPER STRIP as "zero beating," and is very effective for Fully 90% of all the troubles reported the reception of weak broadcast stations. originate in the plug-in coils. The "Junk- s' If the set is actually "zero beating," you Box" constructional article advised a sepa- will hear it squeal when you turn the tuning ration of one quarter of an inch between condenser, Cl, either np or down; in the the grid and tickler windings on the tube critical center position of the condenser the bases; but, judging from our heavy cor- squeal is absent. respondence, as well as examination of FP As remarked in the original article, the several sets sent in to us for test, the com- ticklers specified for use on the tube -base plaining constructors are disregarding the plug-in coils are really larger than neces- sary. Very few of the inquiring construct- TUNING CONDENSER REGENERATION CONDENSER ors seem to have followed the important Ci C2 advice given in the first article, so it will be repeated here. .It the right, a Close coupling between the grid and simple way to tickler windings is necessary to allow the With any one of the coils in the socket, shield the "Junk - detector tube to regenerate. If the feed- turn the tuning condenser Cl all the way B o x " condensers back condenser used (C2) were larger, the in, and start turning in the regeneration against hand capa- condenser. The city, which so coupling would not be so critical; but since set will fall into oscilla- many constructors the condenser has a capacity of only 32 tion at some setting of the latter condenser, find a problem. mmf., we are not allowed much leeway in probably when it is about half -way in. This the coupling. Some experimenters replaced means the tickler is too large. With the this small condenser by a larger one, say tuning condenser at maximum, the set 64 mmf., and are thus able to obtain smooth should begin to oscillate when the regenera- regeneration with less trouble. However, tion condenser is turned to its maximum; The original diagram of when this condition is reached, the receiver the coils of the "Junk - we wish to emphasize the point that, with Box." This was pub- the coils made as specified and with 32- will fall into regeneration with a smooth lished in the first article, mmf. condensers, the set should and does "hushing" sound at all the lower settings though not reproduced of the tuning condenser. as a blueprint. Both work perfectly. original article and blue- REGENERATION CONTROL REGENERATION VS. OSCILLATION prints give the numbers of turns in each coil. A short -wave receiver is worthless if its One of the things that many people do Observe the compara- be controlled not seem to understand is the difference tively narrow spacing regenerative action cannot bet:cccn windings. smoothly. If the set falls into oscillation (Continued on page 671)
www.americanradiohistory.com Radio News for January, 1929 u-l7 The "Lamp -Socket Five" A Simple A. C. Set* Incorporating the Latest Refinements, A Happy Medium Between Big and Small Sets, Easy to Build, Handy to Operate, and Attractive in Appearance. By Beryl B. Bryant TI-IE number of inquiries Of course, if the constructor for full constructional has already a phonograph of the data of a five -tube set cabinet type, all he need do is employing A.C. tubes has remove or swing to one side the led the staff of ltamo NEws to arm holding the sound -box s" design the receiver described in that it cannot interfere with the this article. There is nothing movement of the pick-up device new about the circuit, nor does as it travels across the face of it contain any mechanical inno- the record. An extension cord vations; it is nothing more than leading front the pick-up to the a conventional, tuned- radio -fre- radio set completes this ar- quency receiver employing A.C. rangement. tubes. It comprises two stages of tuned phonograph turntable in a cabinet of the radio frequency using 226-type tubes, a console type, for greater ease of operation. CIRCUIT IS SIMPLE detector using a 227 -type, and two stages of transformer- coupled audio amplification Studying the circuit diagram from an- first comprising a 226-type and the tenna to speaker, we find first the antenna -the stage of second stage a 171A -type power -amplifier No. 72 tuned radio frequency with its coil RADIO NEWS -Socket 1.1, its single tuning condenser CI and the tube. FREE THE `Lamp This receiver has been engineered espec- Fire" represents our variable resistor R1, which serves as an BLUEPRINT oscillation suppressor; the last remains in ially for use with the "B" power unit de- ARTICLE' response to a wide de- IL fixed position scribed in the December issue of mand from our readers after it has been adjusted Rio to desired NEws (page 544). Though this assembly was for a set of the all- the point. Then follows the sce- ond radio- frequency described in the Beginner's department, it around type, with a moderate number stage which contains the oscillation ; is nevertheless a very efficient power unit of of tubes, yet giving an amount of am- control PH this stage is tuned by section the latest design and, probably, the most plification that will ensure good dis- one C2 of the two -gang condenser, flexible in the matter of voltage output, yet in any fair radio location, and the other section of which, tance tunes available for home construction. The real providing excellence of reproduction the detector circuit. Two convenient vernier dials operate the reason for its publication in the Beginner's with volume enough for any home on condensers. department was that it requires exactly a good loud speaker. The wiring is In the detector stage the cathode -heater eleven wires to complete the entire assem- simple, and the list of parts, though type tube (227-type) is used; this tube dif- bly which comprises seven components. A long, includes few of any high cost; fers from the 226 -type in that the alter- complete set of constructional blueprints is unless the constructor wishes to invest nating current is not applied directly to the available for free distribution to our read- in the highest tone quality which the filament of the tube, as in the latter, but ers if they will use the Blueprint Coupon in best transformers make available. It the heating clement is electrically separate this issue (page 701) to ask for set No. 70. should be operated with a "B" power from the cathode, which is the electron - In the design of this receiver, as many unit, such as that described in last emitting element (instead of a filament). A conventional features have been incorpo- month's RAnlO NEws, or ally other of return lead must be brought to the cathode rated as would be useful to the average con- good quality. to complete the grid circuit; for this rea- structor. For example, though much has Any reader who wishes to construct s.on a fifth prong is added to the tube lul.e, been said in recent months about the su- this receiver can obtain-postpaid thus originating the common description. perior importance of tone quality over dis- and without charge -a set of Free live -prong tube," for the UI -type. In the tance- getting ability in a receiver, the thrill Blueprints (including full -sized drill- detector circuit we find, also, the conven- of DX- hunting is still very much with us ing layouts and the list of parts orig- tional grid condenser and grid leak ('7 -112; and, according to all evidence, will be so for inally used, with their list prices) by and in the plate circuit of the detector tube, some time to come. With this fact in filling out the coupon on page 701 of the radio -frequency choke coil RFC by- mind, a regeneration control (PH in the this issue, checking "No. 72 -The passed by the fixed condenser C/ì. in this diagrams and pictures) has been included Lamp- Socket Fire," and mailing it to circuit is found also the closed- circuit ,jack in the second radio -frequency circuit. By the office of RADIO NEws. 33 which disconnects the radio -frequency this control the second R.F. stage can be section of the receiver from the amplifier brought to the actual state of oscillation, which is quite effective for successful dis- tance reception. .lack for plug-iu cab(c PHONOGRAPH CONNECTION Another handy addition is the pick -up jack, J3, which automatically places a phonograph pick -up across the primary of the first audio transformer when the plug, to which the pick -up is attached, is inserted in this ,jack. In this way the amplifier sys- tem of the set becomes a tone -quality power amplifier for the phonograph and allows the reproduction of records through the loud speaker of the receiver. All the apparatus required for this is a simple phonograph turntable with a motor (either electric or spring-wound), and a pick -up of one of the types specified for use with radio ampli- fiers, of which there are manv makes now being marketed. A convenient arrange- ment is to incorporate the receiver and The "LampSocket Five," the neat, simple panel appearance of which is shown at the top of RADIO NEWS Free Blueprint Article No. 72. the page, has practically the whole of its wiring run tinder the baAclite sub -panel, as shown here.
www.americanradiohistory.com Radio 1929 648 News for January,
pick -up plug is in- some electrical load is impressed, quality into a post-to-post wiring description of the when the phonograph all details are plainly into the jack. should be taken into consideration with receiver, because serted wiring diagrams be- the detector circuit are the two these items, just as with the audio-frequency shown in the pictorial Following features which may of audio-frequency amplification, transformers. It is rather poor economy to low, the constructional stages which will be one 226-type tube in the first save a few pennies on a component offer some concern to the builder comprising instead. The layouts (they are stage and a 171A -type tube in the second, has a replacement value of dollars. described supplied as full -size working templates with with their respective transformers, Ti and As it would be a waste of space to go T2. To prevent any damage to the speaker windings, a filter system composed of the choke coil IA and the by -pass condenser C8 is inserted in the plate, or high- voltage circuit of the last amplifier tube; these two components are connected to the phone -tip jacks (J1 -J2) into which the tips of the loud -speaker cord are inserted. POWER SUPPLY The various windings within the dotted lines indicating the filament transformer supply the filament voltages for the tubes in the receiver proper. As there are three distinct types of tubes there are three sec- ondary windings on the transformer; the first supplies the 226-type tubes with 11/ volts, the rated filament potential required for the operation of this tube. In series with one side of this winding are three fila- ment- ballast resistors, RG, designed to sta- bilize the voltage being fed to the tube. Across this winding is the V -type resistor R5, which is mounted beneath the sub- panel; its center tap is connected to the variable potentiometer R3, which serves as a biasing resistor for the 226 -tube grids, and is by- passed by the condenser C9. The next winding supplies 21/2 volts to the I heater of the 227-type detector tube. As with the first winding, the filament -ballast resistor R7 is employed here to keep a con- stant voltage across the heater; the center - tapped resistor RS connects to `8-1- 221/2" to prevent hum from the heater of V3. The third winding is for the 171A -type power - amplifier tube in the last socket, which re- quires five volts for filament lighting; this winding, like the others, is equipped with a constant -voltage filament -ballast resistor R10 and a center -tapped resistor R9, which in turn is connected to another resistor R4 by-passed by the condenser C10. The last - mentioned resistor provides the grid -biasing potential for the power tube. CONSTRUCTION 'VERY EASY At first glance, the reader may believe that the construction of this receiver is com- plicated; it is not. After all the apparatus has been mounted on the front panel and sub -panel, it is a simple matter to run the leads as shown in the layout and pictures. Obviously, with this type of wiring, it is extremely important that well -insulated hook -up wire be used; in building the lab- oratory model of this receiver a solid wire protected by a covering of the "push- back" type was used, and proved very efficient as well as easy to handle in work. The specifications of parts listed below offer the constructor a wide choice of manu- facturers; however, he is advised to pur- chase the best material within his means. Alternating- current operation is a "ticklish" proposition and requires tried and tested apparatus to insure the desired results. For example, in choosing the audio- frequency transformers, the builder should bear in mind that these two components will do more to establish the quality of the re- ceiver's reproduction than any other ap- paratus in the set; therefore should be the very best he can afford to purchase. When selecting the filament transformer, resistors, condensers and other components on which
www.americanradiohistory.com Radio News for January, 1929 649 the Free Blueprint sheets) for the front number of types and styles on the mar- diagram and run the leads to standard bind- panel and sub -panel are self -explanatory; ket. ing posts which may be mounted on the rear however, the sub -panel brackets used to sup- Some readers may prefer to equip the re- edge of the sub -panel; though, as evidenced port the sub -panel are not recommended as ceiver with binding posts instead of the by the pictures, their mounting may cause home-constructed components. It is far recommended plug-in cable used on the set; a good deal of crowding. Therefore, we simpler and cheaper to purchase them if preferred, this may be clone without any suggest that the constructor include the ready -made, as at present there are any difficulty. Merely ignore the cable in the plug -in cable in his assembly; it is well worth the difference for the convenience, neatness and fool -proof safety it offers. LIST OF PARTS NEEDED One bakelite front panel, 7 x 24 -inch; One bakelite sub -panel, 10 x 24-inch; Two bakelite sub -panel brackets, 81/ x 1 x % -inch; Nine inches of bakelite tubing, 11/2 -inch diameter; Two dials, vernier type; One variable condenser, .0005 -mf., Cl; One double variable condenser, .0005 -mf. each section, C2 -C3; Two audio- frequency transformers, Tl =1'2; One 30-henry audio -frequency choke coil for output, L4; One filament transformer, with three wind- ings to give 1%, 21/., and 5 volts; Four sockets, UX -type; One socket, UY -(5- prong -) type; One oscillation control (phasatrol), PH; One variable resistor, 0- 1,000 -ohm, wire - wound, RI; One grid condenser with grid -leak clips, .00025 -mf., C7; One grid leak, 3- megohm, R2; One radio -frequency choke coil, 80- milli- henry, RFC; One fixed condenser, .001 -mf., C6; Four by -pass condensers, paper -type, 0.5- mf., C4- C5- C9 -C10; One by -pass condenser, paper-type, 1.0 -mf., C8; One resistor, 0 -2,000 -ohm, 5 -watt, R3; One resistor, semi-variable, 0- 3,000 -ohm, 5- watt, R4; r+i One resistor, center -tapped, "V" -type, 10- ohm, R5; 0-0 One resistor, center -tapped, "V" -type, 20- ohm, 118; One resistor, center -tapped, "V" -type, 100 - ohm, 119; Three filament-ballast resistors, 226 -type, 116; One filament -ballast resistor, 227 -type, R7; One filament -ballast resistor, 1/1-ampere, R10; One plug -in cable, seven-pin type; One power switch, 110 -volt type, PrSw; One closed- circuit jack, three -prong, J3; Two phone -tip jacks, for loud speaker, J1- J2; Two binding posts, for aerial and ground leads; One quarter -pound No. 30 D.C.C. wire for coils; Two 25 -foot rolls hook -up wire, push -back type; Three vacuum tubes, UX -226- (A.C.) type, 11/2 -volt filaments, V1- V2-V4; Orie vacuum tube, UY -227- (A.C.) type, 21/, -volt filament, V3; One vacuum tube, UX -171A -type, V5; Six feet silk -covered lamp cord, for 110 - volt input to filament transformer. MAKING THE COILS It is best, perhaps, when assembling the receiver to get the coils wound and out of the way so that they can be mounted in po- sition at the proper time, and wired into the circuit upon the completion of the assem- bly. The first step is to cut the nine -inch bakelite tube into shorter lengths, three inches each; of course, if these tubes have
www.americanradiohistory.com 650 Radio News for January, 1929
been obtained cut to size, so much the bet- Fig. 5 ter. When winding the coils, first drill two At the right, the way small holes about half an inch from one end in which the "Lamp- of the tube; this is to secure the terminal of Socket Five" is con- nected to the Adjust- the wire while the coil is being wound and able "B" power unit also after the coil has been completed and described in our De- wired into the circuit. These holes for cember issue, and fastening should be drilled about an eighth which is well suited to the purpose. The "C" of an inch apart, so that the end of the terminals are not used wire can be inserted into the form at one because suitable resist- PLUG-IN CABLE ors, hole and out at the other; when doing this, with the needed FROM RECEIVER be sure to leave about six inches free to balancing arrangement, 110 VOLT LINE are provided in the set. TO 'B' POWER UNIT make connections easily. Wind 75 turns for the secondary, taking care that none of the turns overlap; after Fig. 4 this number of turns has been wound, drill Below, details of R.F. coils to Nile with two holes as at the beginning of the wind- .0005 -mf. condensers. °B° POWER UNIT VOLTAGE DIVIDER ing, and secure the winding in the same The windings a r e spaced about a quarter - manner. Leave the same amount of free METHOD OF WIRING CABLE end for the connection. is inch apart. Ample The primary room for mounting is TO°B'POWER UNIT. UNUSED wound with 20 turns of the same gauge of left at one end. wire as the secondary (No. 30 D.C.C.) ; and the same method of securing the ter- ASSEMBLY AND WIRING minals is employed with this as when wind- ing the secondary. Prepare LI, L2 and L3 It is suggested that the radio -frequency, in the same manner. detector and audio- frequency circuits be After the other components have been so ->1 wired first and then the filament circuits; mounted that the assembly is ready for the this will add no difficulty to the wiring and mounting of the coils, the forms may be se- will help to produce a neater and more ef- cured to the sub -panel by means of two ficient job. After the radio- and audio- straight Z- brackets, one at each end of the frequency circuits have been wired and coil forni, or with two 1 -inch brass pillars. PRIMARY checked, the A.C. lines can be added. When The angles of mounting the coils, shown in 20TURNS doing this note in the circuit diagram that the illustrations accompanying this article, 430 D.C.C. the filament leads are twisted; this construc- are different to prevent inter-coupling of tion creates a capacity which obviates the their magnetic fields. Placing two coils necessity of placing condensers across the with their axes in line, or parallel, will bring SECONDARY leads to by -pass out the 60 cycle -hum. The about such coupling between the two coils; 75 TURNS leads requiring this twisting are so indicated this condition is undesirable because it re- 30 D.C.C. on the circuit diagram; do nbt overlook this sults in inability to control the oscillation of part of the job. Often a receiver with all a receiver. For this reason, it will be no- circuits testing correctly will have a hunt ticed, the coils placed at the ends of the which will defy trouble- shooting; merely be- sub -panel are mounted horizontally at right COIL DETAIL cause of the simplicity of the cause- angles, and the center coil L2 vertically. (SAME FOR THREE COILS) straight, parallel A.C. leads.
With practically every length of wire, except two, run beneath the reception conditions. Both within and without, this set is a most panel, the "Lamp-Socket Fire" has an especially attractive appear- attractive one; and, if it is built with component parts of good ance when the cabinet cover is lifted. Lined np at right angles, quality, the results which the builder may expect are very good. as shown, the small coils do not require shielding under ordinary The design shown is a safe one to follow.
www.americanradiohistory.com Radio NcTLV for January, 1929 651
The ground and ground connection for this set must be as nearly perfect as the SEND THE COUPON IF YOU WISH FREE BLUEPRINTS! constructor can manage with whatever is SO many thousands of Free Blueprints are mailed each month by RADIO NEWS at his disposal. Since the early days of that the total cost is too high to waste any. Originally, each request was accom- radio, a good ground has meant good recep- panied by ten cents, which did not cover the cost. Since then, this service has been tion, and a poor ground little reception or made gratis; and it has been necessary to reprint edition after edition of the more none at all. Even more care must be em- popular blueprints. ployed when using A.C. units and, es- The sole purpose of this unusual offer was to encourage home radio building- pecially, A.C. tubes. Where buried plates which it has evidently done. But, as each article carries the circuit diagrams, etc. - everything in fact but the drilling layouts, manufacturers' names, and other purely or wires cannot be used, experiment with constructional details -there is no good reason why anyone should sena for a Free the various grounds at hand; for example, Blueprint unless he intends to build, and not to use it for wallpaper. To build, he run a wire to the cold -water pipe, the steam must have the magazine containing the complete article. radiator pipe, try each one and then com- For that reason, in requiring that applicants for Free Blueprints in the future binations. Probably the best way to do this use the coupons contained in the same issue of RADIO NEWS in which the descriptive is to tune in a weak station and then try the article is published, we do not put a hardship on any bona -fide constructor; but will various grounds and combinations till you assure the distribution of the blueprints only among those who will put them to find one giving the best signal strength; practical use, warranting the cost of their printing and distribution. The Free Blue- will with print coupon covering apparatus discussed in this issue is on page 701. Readers this indicate the ground the least seeking other diagrams and information are referred to the notice at the head of the resistance and, obviously, the one to be "1 Want to Know" department, on page 661. used. No Further Blueprints Can Be Sent Free Without Coupon Do not overlook the importance of the aerial; because of the sensitivity of this receiver it is highly important that the TESTING AND OPERATION it by ear (that is, by the quality of the aerial and lead -in be well insulated from speaker's reproduction) if he then takes any other objects. For the aerial wire solid After all wiring has been completed and voltmeter readings of his final adjustments. No. 14 enamelled is recommended because the subsequent thorough checking has The experiment will be a revelation as to acid-smoke and soot, which generally at- proved that every circuit is as it should be, the absolute necessity of meters. tack and corrode bare copper wire and thus the various colored leads of the plug-in This receiver requires approximately 30 lower its efficiency, cannot affect enamelled cable are connected to their respective posts seconds to "warm up "; or, in other words, wire. Also, because of the sensitivity of the on the voltage- divider of the "B" power the heater of the 227 -type detector tube re- set, the length of the aerial need not be unit. A short study of the diagram illus- quires that length of time to heat up to the near as great as that required by the gen- trating these connections (Fig. 5) will sim- temperature where the cathode begin eral run of receivers. must be plify matters. After all external connec- to function. However, this time -lag charac- battery It tions have been made the switch is turned teristic applies only to the detector and not remembered that, the longer the aerial, the on; but the set is not yet ready for opera- to the other tubes in the set, which begin greater the pick -up of electrical noises as tion. 'l'hat is, it will bring in signals, but functioning almost instantly with the turn well as signals. Seventy-five feet should be not with the fullest efficiency or anywhere of the switch. sufficient for all purposes. near it; for the simple reason that the "B" power voltages must be AERIAL J3 checked with a 0 -200 R2 R..- I L1 ..131 1 VI V3 TI V4 T2 VS L4S high -resistance voltmeter :: J1 in order that the con- 0 structor may know ex- '1 o actly what potentials are W ó being applied to the re- aaZ oJ2 ceiver. It must be re- tit ,(BLUE) membered that the power GROUND rrimrurarr unit here recommended (BRPo) j B+45V. for this receiver (sec I(YELLOYO 1tAmo NEws for Decem- rt10 B+PWR I (RED) ber, 1928, page 544) em- Fig. 1 7 r.ryrr I 8+22' V ploys a set of variable The schematic circuit of the "Lamp -Socket ; I(OREEi Five," with its built -in `.1" power supply. r.R7 t a p s on its resistors R6 IBLACK)} .4 "B" unit is required; the `C" voltages which control very nicely are automatically obtained. Most of the 4áSLATE1 SRvo the voltage output of the adjustable controls shown are adjusted once r AJ for best results and then left alone. pR-SW .110 A.C. To unit; 1 most surprising 11 1 1A B-FWRUNIt readings can be obtained P LUa N \ CABLE from the voltage- divider 1 L______I ó6Ò06ööao _J nov. posts after one adjusts End of Monthly Constructional Prize Contest RADIO NEWS regrets that it must W. H. Scheppele, of Waterloo, Iowa, for dress in his first letter, and became very announce the discontinuance of the his "Combine" receiver. indignant because it was not answered. Hundred- Dollar Constructional Prize The rules of the contest stated very - The receipt of all communications rela- Contest inaugurated with its April, 1928 plainly that no one w'oudd be eligible for tive to the contest was acknowledged very number. Although a large number of en- a prize unless some experimental work had promptly, by special cards. If any read- tries have been received, so few of them been done and the practicability of the de- ers submitted entries and received no word conform even to the mechanical require- vice had been demonstrated by the builder. of their fate, they failed to indicate ade- ments of the competition that it has been Most of the entries consisted merely of ideas quate return addresses, or their own stamped impossible for the editors to award the or suggestions, accompanied by the request and addressed envelopes were incorrectly prizes to more than four contestants during that RADIO NEWS do the experimental work made out. The editors are helpless in cases a period of seven months. The awards necessary for their full development. Many of this kind, for they cannot be expected to went to W. Francis Goodreau, of Provi- correspondents who claimed they had new know the addresses of such correspondents. dence, R. L, for his "R.F. Short -Wave circuits did not trouble to send in even the A number of the entries in the contest Broadcast Receiver "; to David Grimes, of diagrams, without which the editors could could not be considered as prize winners, New York City, for his "R.F. Booster not possibly determine the patentability, but are nevertheless deserving of some space Unit "; to Herbert J. Reich, of Ithaca, or even the practicability, of the ideas. in the magazine. These will be published N. Y., for his "Nentroheterodvne "; and to One than even neglected to include his ad- and paid for at a special rate.
www.americanradiohistory.com 652 Radio News for January, 1929
A Self -Supporting Winding A Double -Ended Plug -In Coil should be at least 4 or 5 inches in length so that they can be worked with some wire THE art of winding radio coils has in- WHAT might be termed a double-Action to spare. The grid coil is wound, a quarter deed undergone a change since the days plug-in coil is herewith submitted for of an inch above the tickler winding, with when coil winding was a matter of starting the "wrinkle" fan with an eye for labor- the same procedure as to leads outlined work at the end of the table where one saving devices. Before proceeding with the above. Leave an inch and a half or two end of the coil form was located and, after constructional data, it may be well to ad- inches between the sets of windings, ar- many days of painstaking turn -by -turn la- vise the builder that ample space should bor, iinally arriving at the other end of be left between the two sets of windings, and that care should be taken to see that, while the two windings of each set should WINDOW SHADE be wound in the same direction, the two RING sets should be wound oppositely. A bakelite, or heavy cardboard, tube 6 or 7 inches in length with an inside diam- eter of 1 -3/8 inches, so that it fits over FILLED WITH the MELTED SEAL- average UX base, is obtained for the TUBE coil forms. ING COMPOUND On one end wind a tickler, pro- BASE AND ALLOWED viding for the terminals by drilling or COIL TO HARDEN punching a hole at each end of the winding; so that the terminals may be brought down Fig. 1 through the inside of the form, into the space -mound tube base and so through the prongs. These R.F. inductor made on a tum- Fig. 2 bler like this is easily slipped off the form. terminal leads, or loose ends of windings, This is a very convenient way to put a prac- time table, where the other terminal of the tical handle on a tube-base plug -in coil. form was located. This coil form averaged some three feet in length, absorbed for its ranging for the terminals of the second in winding sufficient wire to reach from here the saine manner as in winding the first to yonder and, after receiving a half -inch coil. (See Fig. 3.) coating of shellac, was mounted in an up- After both sets of windings have been right position on the operating table so completed, you should have four long ter- that one's hat could be tossed conveniently minals projecting from each end of the over the form upon entering the room. tube. It is then a simple matter to pass As will be seen from the illustration of these ends through the tube prongs; after an ingenious wrinkle (Fig. 1) herewith the bases have been fitted to the form, the coil construction has taken (paradoxically) leads are cut to the required length and a turn for the better in these soft, luxurious soldered. It is advisable to pass a bolt years. In this method four strips of ad- through the forni and the base as sug- hesive tape are placed upon a common gested in the drawing. The top of each tumbler as shown, and the winding placed grid coil is connected to the grid con- over them. The alternate layer of twine denser, and the bottom to the filament is used to space the windings, to reduce the return. -Contributed by Archie Mares, distributed capacity, and thereby increase Cheney, Washington. the efficiency of the coil. After the re- quired number of turns have been wound, the ends are cut (leaving sufficient length Putting a Handle On It for hook -up), the adhesive-tape tabs are folded back and secured, and the self -sup- ATHOUGHT for the short -wave listener porting coil is then readily removed from who builds his coils on tube -bases has the tumbler for use. been submitted by a constructor of the "Junk Box" short -wave receiver, who prob- Fig. 3 ably ran into the difficulty of having his The use of tube base coils coil windings slip off their forms every for Junk -Box and other time they were roughly handled. Obviously sets is commending itself the way out of this difficulty is to fasten to constructors. You can now buy forms without some gripping device to the coil forms, waiting for a tube to blow. so that they can be pulled out of their This stunt results in just socket without touching the winding. How- half as many coils to paw in is over when changing waves. ever, the "rub" that idea that the average tube -base has very thin walls and requires delicate handling when drilling large holes, such as are needed for a suit- able bolt. In order to secure a suitable grip and still avoid tampering with the base, SUa- PANEL.= COUNTERSINK Fig. 4 LIGHTLY UNDER our contributor suggests the following: .4 long panel is apt to SUB --PANPAN EL - Take some of the sealing compound from \e develop what engineers call a buckle. The author the top of an old discarded "B" battery, WASHER of this wrinkle applies a melt it and pour the mixture while hot MACHINE SCREW -I =ÿ' course in structural de- into the tube base; while it is still in a TWISTED COPPER sign to the problem of liquid or semi -liquid state insert a window - WIRE preventing any such occurrence. curtain ring in the position shown in Fig.
www.americanradiohistory.com 1Kadio News for January, 1929 653
2, opposite. Allow the scaling compound with a switching circuit (as shown in Fig. Stiffening the Sub -Panel to harden; the portion of the ring sticking 8) by means of which either receiver may A S a rule, lengthy sub -panels least out of the compound after it has cooled have its filaments lighted and be connected -at L when weighed down by makes a very convenient handle by which to the aerial without disturbing the settings 1 transformers the coil can be safely inserted or withdrawn of the other receiver. -Contributed by of the type found necessary for the quality desired days from the socket. -Contributed by D. M. Dwight P. Carpenter, Peekskill, N. Y. of reception these -develop Brown. Laying Out a Scanning Disc A Vernier THOUGH RADIO NSWS does not recom- SNORT. BROADCAST Simple -Compensator WAVE RECEIVER mend the building of television scan- RECEIVER ASIMPLE, but effective, vernier con- DOUBLE -POLE ning discs by the experimenter -unless he DOUBLFTNROW trot can be constructed in little time SW ITCI1 with parts usually found in the experi- is an expert in precision machine work and menter's spare-parts box. A strip of zinc possesses the necessary power drills -there . are a good many amateurs who desire to SHORT-WAVE BROADCAST "roll their own," in spite of some very good FILAMENTS RECEIVER TUNING CONDENSER GILAMENTS and obvious reasons why they should not. A + However, here is a scanning -disc method ZINC PLATES 2'x I'/z' that might give some results; and, though its meeting with success cannot be guar- anteed by this magazine, it is published for Fig. 8 the handy constructional hints it contains "Combine" receivers grow in popularity. The simple switching device above is convenient. KNOB ON for those who would care to try their hand FRONT OF PANEL at drilling a house -made disc or two. First, obtain a large phonograph disc with indentations amidships which are everything one -side recording (a two -side record can but artistic, and often disastrous. While be used by sandpapering the grooves out a third, or even a fourth, sub -panel bracket off one side), and place a 7/16-inch mandrel may be installed to overcome this sagging in the center hole of the disc. A piece of tendency, the idea of so much additional SOLDERED string is then wound a number of times equipment may not appeal to the average - about the mandrel, bringing the end of the constructor. Furthermore, the Rumore brack- BRAANGLE string near the edge of the record, a ets one adds to time underside of a sub -panel, SPRING BRASS after is in the greater the difficulty in wiring the PANEL AND C\ loop tied the string and a pencil placed BASEBOARD. in the loop; then one more turn is wound receiver. Fig. 4 shows a way in Fig. 5 of preventing sag sub -panels which is both simple and cheap. This "book- type" condenser is easily made and will be useful with many old -style condensers Some readers may recognize this wrinkle as and for other purposes around a set. a miniature of the familiar one employed to keep time aerial mast from bending with or sheet brass is soldered to the stationary the stress of the antenna. This sag-pre- section of the condenser which makes con- venter offers, not only a secure brace, but tact with the stator, or fixed plates of the also a convenient means of grounding the instrument; and is placed in a position per- various "A-" leads on a common lead, pro- pendicular to the condenser base, as shown viding the support wire is of copper. - in the illustration (Fig. 5). The second, or Contributed by E. K. Jewett. movable, plate is soldered to a shaft so that, at maximum, there is an air space of about an eighth of an inch between the two plates. 'l'he details of the shaft mounting are Bloop to Yourself Alone self-explanatory; a standard rheostat knob T last! Use has been found for the equipped with a set -screw fastener is used A "squeal of the pig!" Just at the on one end of the shaft, which is restrained time when great heads are huddled in an from undue motion by means of the brass effort to concert a mighty heave, so that angle, mounted on the baseboard, and a Fig. 6 it may be sufficient to toss all regenerative collar. A strip of spring brass aids in this receivers in the ocean, a use is If the RADIO NEWS television disc blueprints found for control and serves also as a wiping contact do not suit, you can design your own by the their "squeals." The suggestion outlined for the movable plate of the vernier. This simple method above. (6f'c dare you to try itl) below was hit upon by . a would -be trans- Rontact should exert a pressure heavy enough mitting "ham" who desired to learn the to prevent the plate from moving of its about time mandrel, giving the line for the code and did not care to use a buzzer be- own weight after it has been brought to scanning holes. To insure even spacing cause of its "far-away" sound, when used the desired position. The approximate size of the scanning holes, place a 360- degree without phones, and its uncomfortable, of the vernier plates is 2 x 1m/.. inches. - dial over the exact center of the record and squawky note when used with phones. Be- Contributed by Walter Fisher, New Haven, secure it so that it will hold its position side the standard regenerative receiver, the Conn. until no longer necessary. It is then a accessories required are, a pair of phones, simple matter to draw 48 or 24 radial lines (Continued on page 675) from the dial divisions. Where A Double-Receiver D.T. Switch each intersects the line drawn TI-IE popularity of the shorter waves has with the pencil in the looped SET CONNECTING STRIP brought about a rather heavy demand string, drill a hole 1/16 - PHONES B+AMP B +DET B- A- A+ ONO. ANT. for short -wave receivers; which demand, in inch for a 24 -hole disc, 1/32 turn, has presented a good many minor for a 48-hole disc. After com- TRIPLE-POLE- AERIAL problems to the builder. Many of these SINGLE -THROW pleting the drilling, and finish- SWITCH have been solved by the manufacturers- ing with sandpaper, it may be such as the design of a short -wave adapter advisable to fasten the dial to which is plugged into the regular broad- the record; so that the dial may cast receiver, and makes use of that set's serve as a motor -shaft coupling. amplification system. Other systems per- -Contributed by George flinty, mit a choice of long or short -wave recep- Victoria, B. C., Canada. tion, by amemns of switches which throw in L or out of the circuit suitable inductances Fig. 7 GROUND and capacities to bring about sufficient Throw open this switch and oscil- wavelength changes. However, one of the late to your heart's content. (A t z4 - TELEGRAPH KEY best methods, from the standpoint of effi- double -throw switch and jumper would provide also a good ground 'B BATTERY ciency, is to employ two separate receivers fur the aerial when not in use.)
www.americanradiohistory.com Radio News for January, 1929
FANS HEAR THE WGY CALLING ITS MATES the Pacent Ultimax. For tone and volume this Short -wave fans throughout the world have had is the best five -tube hook -up I've handled. How- NEws will welcome any definite in- the opportunity to hear a three -way conversation RAnto ever it holds one disagreeable feature, its oscilla- between America, Java and Australia by phone. formation from our readers about un- tions in the lower channels. This set being some- During recent experiments between W2XAF, listed stations which you may hear putting thing out of the ordinary, I'm at a loss as to Schenectady, on 31.4 meters and A2ME, Sydney, on programs, only if you hear the call or hou- I can insert a control. Australia, 28.5 meters, two -way conversation was the announcement of location. Please give GEO. H. CARTER, conducted with the greatest of ease in the early the wavelength as closely as you can esti- 308 Mulberry Terrace, Albion, Mich. morning at the American station -which corres- mate it. Because of the member of experi- (A high -resistor in the "B }" lead of the R.F. mental transmissions by ponded to late in the evening in Australia. amateurs and amplifier is a simple means much favored at the others, we On October 17 the announcer at 2ME, R. E. cannot undertake to list such present time. From 0 to 100,000 ohms is a good Farmer, informed the American announcer, A. B. stations in the short-wave broadcast list on range.-EDITOR.) Hitt, that the Dutch station AXE, Bandoeng, another page, n less confirmation is re- ceived of their having a regular schedule; Java, 15.9 meters, desired to come into the dis- RECEPTION ON A.F. STAGE cussion; and, with the aid of two short -wave re- but all definite information received will Editor, RADIO ceivers at each station, the parley was held as be published here, Please consult data NEws: familiarly as over a party telephone line. The we have published before writing for in- Kindly publish a few hints on short -wave troubles. Australian station is nearly ten thousand miles formation; we have no way to identify (See page 646) I constructed the "Junk -Box" but from Schenectady, the Javanese station about as a station by its program or language, since I can't get anything; it sounds like the ocean far, and the' two latter are over three thousand many foreign stations transmit in several roaring. Batteries, tubes, phones and parts used miles apart. The short -wave conversation was heard languages; nor even by its approximate in set are all O.K. Now here's the mystery. 1 by listeners in Peru, and probably in most other wavelength, unless it is one of the larger can pick up Base 9, Coast Guard short-wave sta- parts of the world. and best -known transmitters. tion at Lewes, Delaware, without any plug -in coils in the sockets. \\'hat's the reason for On October 26 WGY rebroadcast one of these this? (The conversations during the half -hour between 6:30 .111611111 lll 11111111111111111.111111111.ll I lllllllllll 111111,,:1111111 111111.1111111llll .lll 1111 audio- frequency tube is oscillating and there is and 7:00 a.m., which is the most favorable time sufficient pick -up to get the nearby short -ware for communication with Australia; and on October station from this tube acting as a detector. Test and Chelmsford, England, and hosts in these the A.F. transformer.) I used these same 31 prominent Americans and Australians exchanged parts United States. WGY and CJRX are my most (without the transformer) but made a short -wave verbal greetings, which were also broadcast. The consistent, others to boot are WSGH, WABC, short -wave reception, though at times wonderfully converter and plugged into my receiver and had KDKA, WLW, WOC, KSTP, Long Beach -and plenty of whistles. clear, is not uniform, and at times fades greatly. to many to mention -not forgetting WRNY, our This effect varies also with the wavelength; so EDWARD J. BROCKASAv. ou-n RADIO News station. But of all these the il'ildwood Annex, N'ildwood, N. J. that the reception may be perfect from one direc- first two are the only ones with creditable clarity, tion and almost unintelligible from the other. and they come good. New York and London come A "JUNE -BOX" CONVERTER in very good in their two -way conversation, and Editor, RADIO SHORT WAVES GIVE SURPRISES indeed interesting to a short-wave snooper. Phone NEws: Editor, RADIO NEws: I stated that I couldn't get anything outside stations are hot. I have reached out to Santa Box." Like the many readers of your noted magazine, Barbara, Georgetown (British Guiana) AGB pre- the states on my "Junk- The tables have turned. I made it into a short -wave converter for I'm an addict to the short -wave field, and growing fixed with C, this latter station near to 29 meters; my Browning -Drake and got XDA, Mexico more enthusiastic everyday; and I'm one of the they come in quite regular. And now, in inquiry, City; great majority who find the RADIO NEws far a SPU, Santa Cruz, Bolivia; SPW, SPX, Rio de out- I wonder if any readers have ever received Janeiro; Nauen; distances any other in radio research. That now phone station with call OCYA? I question its ABG, GBH, Grimsby, England; well -known Junk -Box has received many comments, whereabouts. And I presume there were many 7NR, Seldovia, Alaska; EAM, Madrid, Spain; NPM, Honolulu, and AND, Tjelilin, Java. They but all will have to be going some to feel so elated searching the when the Graf Zeppelin came air are all code besides these have got as I. It's a real humdinger. I've tried quite a 11, in a stations; I a this way. Sunday, October I tuned batch of unidentified stations. reason number of hook-ups but the J.B., gives the 'Sailor's phone station which repeated messages in English I believe the Farewell' to the rest.- Got them all beat. I have and German from the Graf Zeppelin; each that I cannot get voice as yet is that I use only rebuilt it time 45 volts on the plates of three tubes. and time again and I'm sure that message being preceded with "JAA- KUN /KLL;" making as she is will give me all satisfaction for the later Where was I? Of course, it into a converter wasn't "JAN -ZSS- KUN /KLL." thing I did with winter. I now find very little of the well -con- By the dials, somewhere close to 20 meters. I'm the only the set; the principal improvement was the grounding end demned body capacity, the only reasons that I sure it wasn't NAA, one of the regulars. I stayed of the other of my aerial. It worked wonders with my Brown- can presume -rubber feet on baseboard and your with this station from 4:45 p.m. until 5 a.m. jocular wooden spoons. next morning. ing- Drake, allowing it to receive KFI with but 45 volts the plates, and with volume enough The many stations I've received include Holland At present, on the higher waves, I am using on to operate a speaker satisfactorily. With the "Junk- Box" it has helped me to get many code stations. The next improvement was the complete elimina- tion of hand capacity; I use a copper panel and mount the condensers directly on it. The making of a short -wave converter from it is another simple matter. I disconnected my audio amplifier in the "Junk- Box," made a plug of an old tube base with leads to the prongs, and attached my lead from the R.F. choke to the "P," and the filament leads in the same manner. I insert the plug into the detector socket of my B.-D. (any receiver will work) and put the tube removed from it into my converter. The aerial and ground are con- nected to the converter and the speaker to the B. -D., and there I have a first -class short -wave converter. It is so compact that the longest lead is three inches; and the whole set could be placed in a cigar box, with enough space for another like it. I would like to hear from builders of the "Junk -Box" who have either good or bad luck with it, and exchange ideas. If anyone can tell why I can't get the foreign broadcasts, I wish they would tell me why and what to do. 1 am about to break into ham transmission and would like to hear from hams who have established records with I99s and would be willing to help out a beginner. CHESTER Tuc HOLSxI, 1012 Bremen St., Milwaukee, Wis. A BRITISHER CHATS ON SOUTH AFRICAN RADIO Editor, RADIO NEWS: Half the 15.45 -meter directional antenna of the Sainte- Assise transmitter of the Societe Francaise Here is the circuit of a really successful screen - Radio- Electrique, near Paris. The "baies" or networks are double, a quarter wavelength apart, grid tube to place before the RADIO NEWS Short - and the squares are half a wavelength on an edge; the vertical center lines are feeders. Only the Wave receiver. As it has been drawn, it uses the middle of the aerial is directly excited. Results obtained with ultra-high speed messages to British S625. which I know -this is of course a Argentina warrant the prediction of "the use in the near future of these short waves for television." six-voit tube -lot doubtless the UX -222 will do
www.americanradiohistory.com Radio News for January, 1929 655
me not to receive equally as well. I can assure your readers that short -wave sets in the Canal Zone are interfering It used to be unusual for but the increase in amplification and the corresponding with their reception of code messages from the \C2X.\L (just across the Hudson River) of have increase in clarity is really remarkable. States, etc., they have recommended to the em- late it is very seldom I receive them. I The first thing which struck me on arrival at ployees and all radio fans within radiating range been wondering if the new bridge over the Hudson Durban in the province of Natal (South Africa) to use a blocking tube (screen -grid) before the affects reception. (Perhaps.) was the complete lack of outside aerials and, upon regenerative detectors of their receivers, I take R. V. PERRY, numerous inquiries, I found that the reason is this opportunity to ask you for a blueprint. 600 (Vest 141 St., New York City. twofold. First, most receivers are of one or J. J. ECKER, JR., two tubes for local reception only and, owing to P.O. box 449, Panama, R. P. the continual static, the indoor aerial was chosen (As a rule, disturbing radiation is very small SORRY, BUT WE CAN'T as the more appropriate. There is, however. another from a regenerative set on Une short :eaves -in Editor, RADIO NEws: side to the question. That is the cost of the contrast to one ou the broadcast band; because the \\'ill you be kind enough to verify the following listening license, £1 15s per annum ($8.56) and natural period of the antenna is suck that it is reception? I just finished making a Silver -Mar- shall "Around- the-World Four," and received 5SW the first two nights. It came in at about 55 on my dial with the 17 -to -32 -meter coil. I receive same coil. Tonight "RADIO NEWS" SHORTWAVE CJRX at about 65 with the the following was part of 5SW's program (list of RECEIVER have received this program with fair SCREEN GRID numbers.) I PLUGIN SECONDARY volume. This is only the third day I have worked UNIT set, and am most happy over my success. AND TICKLER the I E. RAY, MIDGET 5 TURNS r RFC RFC OUTPUT 15822 Quincy Ave., Detroit, Michigan. (RADIO NEWS must again emphasise that we cannot undertake to verify reception in this manner for any stations except our ores, WRNY- 1V2XAL, New York City. We have no doubt that our correspondent heard 5SW, which relays 2L0, London; but for a certificate of that fact, he must address the British Broadcasting Co., Savoy Hill, .00025 London W.C.2, England. Please do not ask us for verifications.-EDITOR.)
L SHORT -WAVE PRESS REPORTS A Nairobi (Africa) correspondent writes to Popu- lar Wireless that the new Nairobi station 7L0 "A+" "B+ B+120 "A-" A+ has been working on 150 meters for some time and PLUG IN FROM 80" never on 100. On October 1st transmission started meters. Times of transmission are 3 TURNS UP on 35 and 400 now and for the future, until further notice, 11:00 a.m. to 2:00 p.m., E.S.T., daily and Sunday. Mr. Somerset adds an R.F. stage to the RADIO NEws Short -Wave Receiver, Model 1927, and further filters the output with a .second R.F. choke and by -pass condenser. The tube he uses "Pioa, Lisbon, Portugal," is the call of a Portu- is a British one of different appearance from the UX -222. guese experimental station broadcasting around 45 meters. Announcements before and after each number of the program are made in Portuguese, those difficult to shock it into oscillation. However, the doubtless the indoor aerial is safer for Spanish, French, German and English. who do not wish to pay this exorbitant charge. screen -grid R.P. adds notably to the value of the It appears, according to the African Broadcasting set in amplifying weak signals; and this refinement now broadcasts only once weekly, Co., that very little interest indeed is shown in is therefore being adopted more and more by short- Bandoeng (Java) Wednesday, 7:40 to 9:40 a.m., large sets. of the order of five tubes or more, wave entha siasts.- EDIros.) viz., every from 15.93 because- though there are two stations at Johan- E.S.T.; ANII on 17 meters and ANE on They announce in Dutch, nesburg and Cape Town, respectively 1000 and meters simultaneously. SHORT -WAVE AERIALS and German. 900 miles from Durban -their programs are not English, French worth listening for because of the appalling static Editor, RADIO NEws: suggest you give us, in one of your always present. I that forth- Eiffel Tower, Paris, is now conducting experi- issues, an on short -wave receiving meters in the morn- On the whole, the quality of broadcasting is coming article mental transmissions on 31.1 aerials. (One will probably soon.) From very good, but the times of transmission are very appear ings and afternoons. my own experience last May when I built my abbreviated. As a general rule, stations do not short -wave set, I found I was passing up a num- start transmitting before 5 p.m. South African ber of stations below 50 meters. Recently built WISHES MORE NEWS BROADCASTS time and close down at 10:30 p.m. (3:30 p.m. I NEWS: Eastern Standard Time). One explanation is the the "Junk.11ox;" on 30 meters down I do not Editor, RADIO use over fifteen feet aerial and most of the Respecting Danish broadcasts, it may be of fact that, as people here are living in a sub -tropical of readers to know that there are two region, everything starts very much earlier in the time only ten feet. In one evening, on a ten -foot interest to your aerial, I received one station in California, Winni- short -wave stations operating experimentally in mo - g. For ninety -nine days out of a hundred, peg, a Spanish station on about 31 meters (PCJJ's Copenhagen. Tbey are 711K, "The Midnight Sun" a most brilliant sun greets them at 6:30 a.m. and Spanish program, perhaps) and a French commer- and 7RL, their wavelengths being approximately leaves them at 6 p.m., practically throughout the code a mine picked 32 and 42 meters respectively. (loth of these have year. Therefore, most people turn in at shortly cial station, which friend of up. These stations all came with good volume, been received at good strength in London, and as after 10 This seems amazing to European p.m. except for fading. (Continued on page 694) listeners when Madrid (for instance) keeps on till 1:30 a.m. Regarding the short waves, one or two interest- ing facts stand out: static is also very prevalent down to 20 meters and one lias to be a real enthusiast to listen to Schenectady, owing to the 8-15MEG time difference. W2XAF is very well received 201 A 201 A 216 A 6:1 201 A indeed about five in the morning. W2XAD and 5SW (England) are not so successful because. for some apparently unknown reason, the baud between 21 and 25 meters is received extremely badly in South Africa. I once heard W2XAL's short -wave transmission very well at about 2 a.m., SAST, Nairobi, Kenya, on 90 meters is also well received, RFC static permitting. Ai I shall be delighted to get back to Europe, where f B radio waves are far easier to tune in than out, 01 MF. 845- notwithstanding that the climate of South Africa o.G is wonderful; always sunshine, never rain. I would like to ask my American friends to thank 0005 their stars (and stripes) that they have more than MF three broadcast stations. E. T. SOMERSET. w NAVY RECOMMENDS R.F. STAGE
Editor, RADIO NEWS: a= ' I am an assidous reader and find Itnuto NEws ii11C 111 MF the grandest radio publication that I know of. X100.000 OHMS '8.90' 1 MF Lately I have been particularly interested in the
articles treating with short waves; as in this country .005 MF. this is the only reception worth while listening to. '!'lie long waves bring along too much static to Fig. 1 be of any use at all. In the October issue you have a splendid article llr. T'an Koolbergen's combination ingeniously uses the same oscillator condenser for both Jong- on a completely -shielded short -wave receiver, free and short-wave superhets. We can conscientiously recommend any constructor to steer clear of blueprint No. 66. As the naval authorities in the it unless he is used to finding his way out of the woods alone on a dark night. The description Canal Zone are complaining that the amateurs' appears on pages 698 and 699, in the continuation.
www.americanradiohistory.com 656 Radio News for January, 1929 New List of Broadcast Stations in the United States
Radio ti Radio a Radio .r Radio Call BROADCAST STA. é Call BROADCAST STA. a X% Call BROADCAST STA. a Call BROADCAST C ti- 3 ó ä é STA. i Letters Location 3F f.3 Letters Location Letters Location I! a,3 Lotten Location ;f 3
KO KA East Pittsburgh, Pa.. 306 25000 KGB Oakland, Calif 380 10000 WBAK Harrisburg, Pa. (day). 268 500 WOHP Mt. Clemens (Detroit) KDLR Devils Lake. N. D 248 100 KG RC San Antonio, Texas 219 100 WBAL Baltimore. Md 283 10000 Mich. 242 750 KD Y L Salt Lake City. Utah 232 1000 KG RS Amarillo, Texas 213 1 WBAP Fort Worth, Texas 375 5000 WO MS See WLB KEJ K Los Angeles, Calif 240 500 KGTT San Francisco, Calif 211 WBAW Nashville, Tenn. 201 5000 WGN Chicago, Ill 416 25000 KELW Burbank Calif. 384 500 KGU Honolulu, Hawaii 319 500 WBAX Wilkes-Barre, Pa 248 100 WGR Buffalo. N. Y 545 50 KEX Portland, Oregon 254 5000 KG W Portland, Oregon 484 1000 WBBC Brooklyn. N. Y. City 214 500 WGST Atlanta, Ga. 337 500 KFAB Lincoln. Nebraska 389 5000 KGY Lacey, Washington 250 10 WBBL Richmond, Va 219 100 W G Y Schenectady, N. Y. KFAD Phoenix, Arizona 484 500 KHJ Los Angeles, Cali/ 333 1000 WBBM Chicago, II. 389 25000 (Time limited). 380 50000 KFAU Boise, Idaho 240 1000 KHQ Spokane. Wash 508 3100 WBBR RossvWe, N. Y. City 231 1000 WHA Madison. Wis 526 750 KFBB Havre. Montana 220 250 KICK Red Oak, Iowa 211 WBBW Norfolk, Va 250 100 WHAD Milwaukee, Wis. (day) 268 250 KFBK Sacramento, Calif 229 100 KJ BS San Franclsco,Cal(day) 273 100 WBBY Charleston. S. C 250 75 WHAM Rochester, N. Y 261 5000 KFBL Everett, Washington. . 219 50 KJR Seattle, Wash 309 5000 WBBZ Ponca City, Okla 250 100 W H A P New York City 231 1000 KFBU Laramie, Wyoming 500 500 KKP Seattle, Wash 211 15 WBCN See WENR WHAS Louisville, Ky 366 5000 KFCB Phoenix. Arlaonn 229 100 KLCN Blytheville, Ark. (day) 232 50 WBET Boston, Mass 220 500 WHAZ Troy, N. Y 231 500 KFCR Santa Barbara, Calif 200 100 KLDS Independence.klo.(Ltd)316 WBIS Boston, Maas 244 500 WHB Kansas City. Mo 316 1000 KFDM Beaumont, Texas 535 50(1 KLRA Little Rock, Ark 216 1000 WBMH Detroit. Mich 229 100 WHBC Canton, Ohio 250 10 K LS 208 WB MS WHBD KFDX Shreveport, Louisiana. 248 100 Oakland, Calif. (day) 1 250 Union City. N. J 207 250 Bellefontaine, Ohio 219 100 KFDM Brookings. S. D 545 500 KLX Oakland, Calif 341 WEN New York City 222 250 W HBF Rock Island, III 248 100 KFEC Porthtnd, Oregon 219 50 K LI Denver, Colo 535 1000 WBO Q See WABC WHBL Sheboygan, Wis. 213 500 KFEL Denver. Colorado 319 250 KMA Shenandoah, Iowa 322 500 WBOW Terre haute, Ind 229 100 WHBP Johnstown. Pa 229 100 KFEQ St. Joseph Mo. (day) 535 2500 KMBC See KLDS WBRC Birmingham, Ala 322 500 WHB Q Memphis, Tenn 219 100 KFEY Kellogg. Idaho 214 10 KMED Medford, Oregon 211 50 WBRE Wilkes- Barre. Pa 229 100 W H B U Anderson, Indiana 248 100 KFGQ Boone, Iowa 229 10 KMIC Inglewood, Calif 268 500 WBRL Tilton, N. H. 210 500 W H B W Philadelphia. Pa 200 100 KFH Wichita, Kansas 231 1000 KMJ Fresno, Calif 250 WB SO Wellesley Hills, Mass. WHBY West De Pere, Wis 250 50 KFHA Gunnison Colorado 250 50 KMMJ ClayCenter,Neb. (day) 405 1000 (Time limited) 384 100 WHIM Minneapolis, Minn 213 500 KFI Los Angeles, Calif 468 5000 KMO Tacoma, Wash 224 500 WBT c.ariotte, N. C 278 10000 WHEC See WABO KFIF Portland. Oregon 211 50 KMOX St. Louis, Mo 275 25000 WBZ Springfield. Masss 303 15000 W H F C Chicago, Ill.. 229 100 KFIO Spokane, Wash. (day) 244 100 KMTR Hollywood, Calif 526 1000 W BZA Boston, Mass 303 500 W H K Cleveland, Ohio 216 1000 KFIU Juneau. Alaska 229 10 KNRC Santa Monica, Calif 384 500 WCAC Storrs. Conn 225 500 WHN New York City 297 250 KFIZ Fond du lac. Win 211 100 KNX Los Angeles. Calif 286 5000 WCAD Canton, N. Y. (day) 246 500 WHO Dm Moines. Iowa 300 5000 KFJB Marshalltown, Iowa 250 100 KOA Denver. Colo 361 12 °00 WCAE Pittsburgh. Pa .. 246 500 WHPP New York City 211 10 KFJF Oklahoma City, Okla 204 5000 KOAC Corvallis, Oregon 535 WCAH Columbus, Ohlo 210 250 WHT Chicago. Ill 203 5000 KFJI Astoria, Oregon 219 50 KO B State College. N. Mex 254 1Ó00Ó0 WC AJ Lincoln. Neb 508 500 W IA Philadelphia. Pa 219 100 KFJ M Grand Forks. N. D 545 500 KOCW Chickasha. OMS 211 100 WCAL Northfield, hitnn 240 1000 W I A S Ottumwa, Iowa (day) 211 100 KFJR Portland, Oregon 231 500 KOH Reno, Nevada 219 WC AM Camden, N. J 234 '00 W IBA Madison, "Vis 248 100 KFJY Fort Dodge, Iowa 229 100 KOIL Council Bluffa. Iowa 238 1000000 WCAO Baltimore, Md. 500 250 W IBG Elkins Park, Pa. (Sun ) 322 50 KFJZ Fort Worth, Texas 219 100 KOIN Portland, Oregon 319 1000 WCAP Asbury Park, N. J 234 500 W IBM Jackson, Mich 219 100 KFKA Greeley, Colorado 341 500 KOMO Seattle. Wash. 326 1000 WCAT Rapid City, S. D 250 100 WIBO Chicago, Ill . 526 5000 KFKB Milford, Kansas (day) 265 5000 KORE Eugene, Oregon 211 100 WCAU Philadelphia. Pa 256 5(110 W IBR Steubenville, Ohio.... 211 50 K F KU Lawrence. Kansas 246 1000 KOW Denver, Colo 216 500 WCAX Burlington, Vt. 250 100 W IBS Elizabeth, N. J 207 250 KFKX Chicago. Illinois 294 5000 KPCB Seattle, Wash 248 100 WCAZ Carthage, Ill. (day) 280 100 W IBU Poynette, Wis 229 100 KF KZ Kirksville, Missouri 250 50 W I B W Topeka, Kans 231 1000 KFLV Rockford. Illinois 213 500 W IBX Utica. N. Y 250 100 KFLX Galveston, Texas 219 100 WIBZ Montgomery, Ala 200 15 KFMX Northfield, Minn 240 1000 WICC Bridgeport. Conn 210 500 KFNF Shenandoah, Iowa 337 500 list of stations in the United States became effective Nov. W I L St. Louis, Mo 222 1000 KFOA Seattle, Wash. 236 1000 THIS11, 1928, by order of the Federal Radio Commission. It is sub- W INR Bay Shore. N. Y 248 100 KFON Long Beach, Calif 240 1000 or rectifications made W IOD Miami Beach, Fla 242 1000 KFOR Lincoln, Nebraska 248 100 ject to any alterations by that body after WIP Philadelphia, Pa 492 500 KFPL Dublin. Texas 229 15 Nov. 11, 1928. W ISN Milwaukee, Wis 268 250 KFPM Greenville, Texas 229 15 WJAD Waco, Texas 242 1000 KFPW . Siloam Springs. Ark. 1 WJAG Norfolk, Neb. (day) 283 500 (da 224 50 WJAK Kokomo, Ind 229 50 Wash 216 500 WJ KFPY Spokane. WC A M Waterloo, Iowa 250 100 KFQB Fort Worth. Texas 242 1000 KPJM Prescott. Arizona 200 15 BA Allentown, Pa 200 100 WJAR Providence, R. I 337 250 KFQD Anchorage, Alaska 244 100 KPLA Los Angeles, Calif..... 526 1000 WCBD Zion. Illinois (day) 278 5000 WJ AS Pittsburgh, Pa 232 441 W C B M 1000 KFQU Holy City, Calif 211 100 KPO San Francisco, Calif... 5000 Baltimore. Md. 219 100 WJAX Jacksonville, Fla 238 1000 K F Q W Seattle, Wash 211 100 KPOF Denver, Colo 341 500 WC BS Springfield. Ill 248 100 WJ A Y Cleveland. 250 50 WCCO Ohio 207 500 KFQZ Hollywood. Cal. (Ltd.) 353 1000 KPPC Pasadena, Calif Minneapolis, Minn.. . . 370 15000 WJAZ Chicago. Ill 203 5000 KFRC San Francisco. Calif 492 1000 KPQ Seattle. Wash 248 100 WC DA New York City 222 250 WJ BB St. WC Petersburg, Fla 297 250 KFRU Columbia, Missouri 476 500 KPRC Houston, Texas...... 326 1000 FL Chicago, Ill. (Ltd.) 309 25000 WJ BC LaSalle, 250 100 816 1000 WCGU Iil KFSD San Diego, Calif 500 500 KPSN Pasadena, Calif Brooklyn, N. Y. City. 214 500 W J B I Red Bank. J 217 500 WCLB N. 248 100 KFSG Los Angeles. Calif 268 500 KQV Pittsburgh. Pa Brooklyn, N. Y. City . 200 100 WJBK Ypsilanti, Mich 219 50 Texas 232 500 K Q W San Jose, Calif. 297 500 WC LO Kenosha Wis 250 100 WJ B L KFUL Galveston, 100 Decatur, Ili... 250 100 KFU M Colorado Springs, Colo. 236 1000 KRE Berkeley. Calif 219 WCLS Joliet, Ili 229 100 WJBO New Orleans, La 219 100 KFUO St. Louis. Dio...... 545 500 KRGV Harlingen, Texas 238 500 WC MA Culver, Ind 214 500 WJBT See WBBM KFUP Denver, Colorado 229 100 KRLD Dallas, Texas 288 10000 WC OA Pensacola, Fla 268 500 WJBU Lewisburg. Pa. 248 100 KFUR Ogden. Utah 219 50 KRMD Shreveport, La. 229 50 WC OC Columbus. Miss. 341 500 WJBW New Orleans, La 250 30 KFVD Venice. Calif. (Ltd.) 428 250 KRSC Seattle. Wash. (day).. 268 50 WCOH Greenville. N. Y. 248 100 WJB Y Gadsden, Ala 248 517 500 WCRW 50 KFVS Cape Girardeau,Dlo 248 50 KSAC Manhattan, Kans..... CM WJJD Mooseheart. Ill. (Ltd ) 254 20000 KF W B Los Angeles, Calif 316 1000 KSBA Shreveport, La 207 1000 WCSH Portland Mll 319 500 KF WC San Bernardino. Calif. 250 100 KSCJ Sioux City, Iowa 225 1000 WCSO Springfield. Ohio 217 500 WJR Detróit, Dlich...... 400 5000 KFWF St. Louis. Missouri 250 100 KSD St. Louis, Mo 545 500 WC W K Fort Wayne, Indiana.. 244 500 WJSV Washington. D. C 205 10000 KF W I San Francisco. Calif 322 500 KSEI Pocatello, Idaho 333 250 WCX See WJR WJZ New York City 395 25000 KF W M Oakland. Calif 322 500 KSL Salt Lake City Utah 285 5000 W DA Tampa, Fla 484 1000 W K A Q San Juan, Porto Rico 517 500 KF WO Avalon, Calif 200 100 KS MR Santa Maria, Calif.... 250 100 WDAF Kansas City, Mo 492 1000 W KA R East Lansing, Mich. KFXD Jerome, Idaho 211 15 KSO Clarinda. Iowa 217 1000 WDAG Amarillo, Texas 213 1000 KFXF Denver. Colorado 319 250 KSOO Sioux Falls, S. D. (day) 270 1000 WDAH Et Paso, Texas 229 100 WKAV Laconia, N. H 229 X50 KFXJ Edgewater, Colo. 229 50 KSTP St. Paul. Minn 205 10000 WDAY Fargo, W KB B Joliet, Ill 229 100 KFXR Oklahoma City, Okla 229 50 KTAB Oakland. Calif 234 500 WDBJ ke. Va 322 125000 WKBC Birmingham, Ala 229 10 KFXY Flagstaff, Arizona 211 100 KTAP San Antonio, Texas... 211 100 W DBO Orlando, Fla 484 1000 W KBE Webster, Mass 250 100 KFYO Breckenridge, Texan 211 100 KTBI Los Angeles, Calif..... 231 1000 W DEL Wilmington, Del 213 250 WKBF Indianapolls, Ind 214 500 KFYR Bismarck, N. D 545 500 KTBR Portland, Oregon 231 500 WOGY Minneapolis, Minn... 213 500 WKBH La Crosse, Wis 217 1000 375 1000 KGA Spokane. Wash 204 5000 KTHS Hot Springs. Ark WOOD Chattanooga, Tenn ... 234 1000 W KB I Chicago, Ill 229 50 KGAR Tucson, Arizona 219 100 KTNT Muscatine, Iowa (day) 256 5000 WDRC New Haven, Conn.... 225 500 W KB Youngstown, Ohio 526 500 KGB San Diego, Calif 220 250 KTSA San Antonio, Texas 232 1000 WDSU New Orleans, La 236 1000 WKBO Jersey City. N. J 207 250 KG BU Ketchlkan, Alaska 333 500 KTUE Houston. Texas 211 5 WDWF Cranston. R. I 248 100 W K B P Battle Creek, Mich 211 50 KGBX St. Joseph. Mo 219 100 KT W Seattle, Wash...... 236 1000 WDZ Tuscola, Illinois 280 100 W KB New York City 222 210 KGBZ York. Nebraska 322 500 KUJ Seattle, Wash. 200 10 WEAF New York City 454 25000 WKBS Galesburg. IB 229 100 KGCA Decorah. Iowa (day) 236 50 K U O A Fayetteville. Ark..... 216 1000 WEA1 . Ithaca, N. Y. (day) 236 1000 WKBT New Orleans, La 211 KGCB Oklahoma City, Okla 219 50 KUOM Nilssoula, Mont 526 500 W EA M Plainfield, N. J 219 100 WKBV Brookville, Ind 200 700 KGCI San Antonio. Texas 219 1 KUSD Vermillion, S. D...... 337 500 WEAN Providence, R. I. (day) 500 500 W KB W Buffalo. N. Y 204 50(10 KGCN Concordia. Kansas 211 KUT Austin, Texas 268 500 W EAO Columbus. Ohio 545 750 WKBZ Ludington, Mich 200 50 KGCR Brookings, S. D 248 100 KV I Tacoa,m Wash. 224 1000 WEAR See WTAM W KEN Buffalo, N.Y. (Ltd.) 288 1000 KGCU Dlandan, N. D 250 100 KVL Seattle, Wash. 219 100 WEBC Superior, Wta .. 234 1000 WKJC Lancaster, Pa 250 50 KGCX Vida, Montana 211 10 KVOO Tulsa, Okla. 263 5000 WEBE Cambridge, Ohio 248 10 WKRC Cincinnati, Ohio 545 500 KGDA Dell Rapids. S. D 219 15 KVOS Bellingham. Wash.... 250 100 WEBH Ch1. 300 5000 WK Y Oklahoma City. Okla 333 1000 KGDE Barrett. Minn 250 50 K W BS Portland, Oregon 200 15 WEBQ Iiaicago,rrlsburgI1, Ii/ 248 50 WLAC Nashville. Tenn. 201 5000 KGDM Stockton. Calif. (day). 261 50 K W C R Cedar Rapids. Iowa... 229 100 WE BR Buffalo, N. Y 229 100 WLAP Louisville. Ky 250 30 KGDP Pueblo. Colorado 248 KW EA Shreveport, La. 248 100 WEBW Beloit. Wis. (day) 500 250 WLB Minneapolis, Minn 240 1000 KGDR San Antonio, Texas 200 100 K W G Stockton Calii 250 100 WEDC Chicago, Ill 248 100 WLBC Muncie, Ind .. 229 50 KGDY Oldham. S. D 250 15 KWJJ Portland. Ore. (Ltd.).. 283 500 WEDH Erle, Pa. 211 30 WLBF Kansas City. Mo..... 211 100 KGEF Los Angeles. Calif 231 1000 KW K St. Louis, Mo...... 222 1000 WEEI Boston. Mass 108 500 WLBG Petersburg. Va 250 100 KGEK Yuma, Colo. 250 10 K W KC Kansas City, 310..... 219 100 WEHS Evanston. Ill...... 229 100 WLBH Farmingdale, N. Y 211 30 KGEN El Centro, Calif 250 15 KW KH Shreveport, La...... 353 200(10 WE MC Berrien Springs. Mich. WLBL Stevens Point, Wis. KG ER Long Beach, Calif 219 100 KW LC Decorah, Iowa (day) .. 236 50 508 1000 (day) 333 5000 KGEW Fort Morgan. Colo 250 100 KWSC Pullman, Wash...... 216 500 W EN Chicago. Ill 345 5000 WLBO Galesburg, Ill. 229 100 KGEZ Kalispell, Montana 229 K W W G Brownsville. Texas... 238 500 WEPS Gloucester, Mass 250 100 WLBV Mansfield. Ohio 248 100 KGFF Alva. Oklahoma 211 1ÓÓ KWTC Santa Ana, Calif 200 100 W EV D New York City 231 5(10 WLBW Oil City, Pa. 238 500 KG FG Oklahoma City, Okla 219 50 KXA Seattle. Wash 526 500 W E W St. Louis, 310. (day) .. 395 1000 W LB X Long Island City N.Y 200 100 KGFH Glendale. Calif 300 KXL Portland, Oregon 240 1000 W FA A Dallas, Texas 288 25000 WLBZ Dover-Foxcroft, Me 484 250 KGFI San Angelo. Texas 229 100 KXRO Aberdeen. Wash. 211 75 WFAN Philadelphia, Pa 492 .500 W LC I Ithaca. N. Y. 248 50 KG Los Angeles, Calif 211 3550 KYA San Francisco, Calif... 244 1000 W FB Knoxville, Tenn. 250 50 W LE Lexington, Mass 211 100 Fl W FBE KGFK Hallock, Minnesota. . . 250 KYW See KFKX Cincinnati. Ohio 250 100 KGFL Raton, New Mexico 219 50 KZM Oakland. Calif 219 100 W FBG Altoona. Pa 229 100 WLIT Philadelphia, Pa 535 500 KGFW Ravenna, Neb 211 50 NAA Arlington Va. 434 1000 W FBJ Collegeville, Minn 219 100 WLOE Chelsea. Mass 200 100 KGFX Pierre. S. D. (day) 517 200 WAAD Cincinnati. Ohio 211 25 WFBL Syracuse, N. Y. 333 750 W LS Chicago, Ill 345 5000 KGGF Ficher. Oklahoma 297 500 W A A F Chicago, Ill. (day) . . . . 3206 500 WFBM Indianapollslnd.(Ltd) 244 25000 WLSI See WDWF KGGH Cedar Grove, La 229 50 W AA M Newark. N. J .. 240 ñ0 WFBR Baltimore, Md...... 268 250 WLTH Brooklyn, N. Y 214 .500 KGGM Albuquerque. N. 31 219 100 WAAT Jersey City. N.J. (day) 280 300 WFC I Pawtucket, R. I 248 100 WLW Cincinnati. Ohio 428 25000 KG HA Pueblo, Colo 250 50 W A A W Omaha. Neb. (day) ... 454 500 WFDF Flint, Michigan. 229 100 W L W L New York City (day) 273 5000 KGHB Honolulu, Hawaii 227 250 WABC New York City 349 5000 WFI Philadelphia. Pa 535 500 WMAC Cazenovla. N. Y 526 500 KG HD Missoula. Mont 211 50 WABF Kingston, Pa 208 250 W F I W Hopkinsville, Ky..... 319 1000 WMAF So. Dartmouth. Dlass. 220 500 KG HF Pueblo. Colo 227 250 WABI Bangor, Maine 250 100 WFJC Akron, Ohio 207 500 WMAK Buffalo, N.Y ..333 750 KG HG McGehee, Ark 229 50 WABO Rochester. N. Y 208 500 WFKD Philadelphia. Pa 229 50 WMAL Washington. D. C.... 476 250 KG HI Little Rock, Ark 200 15 WA B Y Philadelphia, Pa 229 50 WFLA See WSUN WMAN Columbus. Ohio 248 50 KG HL Billings. Mont 316 250 WABZ New Orleans La 250 50 WG AL Lancaster, Pa...... 229 15 W MA Q Chicago, Ill, 447 5000 KGH X Richmond, Texas 200 50 WADC Akron, Ohio 227 1000 W G BB Freeport, N. Y...... 248 100 WMAY St. Loula. Mo 250 100 KG Ili Idaho Falls. Idaho 227 250 WA FD Detroit. Mich. 200 100 WGBC Memphis, Tenn 210 500 WMAZ Macon. Ga 337 500 KG IQ Twin Falls. Idaho 227 250 WAGM Royal Oak, Mich..... 229 50 WGBF Evansville. Ind 476 500 WMBA Newport. R. I 200 100 KGIR Butte. Montana 220 250 WAIU Columbus. Ohio (Ltd.) 468 5000 WGBI Scranton. Pa 341 250 WMBC Detroit, Mich 211 100 KGJF Little Rock. Ark 337 250 WALK WlUow Grove, Pa..... 200 50 WGBS New York City (Ltd.) 254 500 WMBD Peoria, HI 208 500 KG KB Goldthwatte, Texas 200 100 WAPI Auburn. Ala 263 5000 WGCM Gulfport. Miss 248 100 WMBF Miami Beach. Fla 535 100 KG K L Georgetown, Texas 219 100 WASH Grand Rapids, Mich.,. 236 250 WGCP Newark. N. J 240 500 WMBG Richmond. Va 248 500 KGKO Wichita Falls, Texas 526 250 WBAA West Lafayette, Ind... 214 500 WGES Chicago, Ill 220 500 WMBH Joplin, Mo. 211 100
www.americanradiohistory.com Radio Netzcs for Ja)tary, 1929 657
Radio Radio ` Radio o Radio 0 `e Call BROADCAST STA. Call BROADCAST STA. sZ 3q Call BROADCAST STA. Call BROADCAST STA. is w 3q Letter Location Letter Location Letters Location F 43 Letter Location 3f se3
WOAX Trenton. N. J 234 500 W RA Ede, Pa. 219 50 WS IX Springfield, 248 100 W M B I Chicago. Ill. (day) 278 5000 Tenn..... W MBL Lakeland. Fla 229 100 WOBT Union City, Tenn..... 2.29 15 WRAW Reading, Pa 229 100 WSKC Bay City, Mich...... 213 500 W MBM Memphis. Tenn 200 10 W O B U Charleston, W. Va. 517 250 W RA Philadelphia. Pa 208 250 WSM Nashville, Tenn 461 5000 W Davenport, Iowa 300 5000 WRBC Valparaiso Ind 242 250 WS MB New Orleans, La 227 750 W MBO Auburn, N. Y 19 100 0 25 w MB Q Brooklyn, N. Y 200 101 W OC L Jamestown, N. Y..... 298 WRBH Manchester, N. H. WSMD Salisbury, Md 229 100 WMBR Tampa. Fla 48 100 WODA Paterson. N. J 240 1000 (Construct. permit) 500 WS M K Dayton, Ohio 526 200 LAMBS Harrisburg. Pa 210 500 WO I Ames, Iowa (day) 535 3500 WRBI Tifton, Ga 229 100 WSPD Toledo, Ohio 224 .500 W MC Memphis. Tenn 384 500 WO KO Peekskill, N. Y 208 5 00 WRBJ Hattiesburg, Miss..... 200 10 WSRO Dliddletown. Ohio.... 211 100 W MCA New York City 526 500 W O L Washington,D.C.(day) 236 150 WRBL Columbus. Ga. 250 50 WSSH Boston. Mass.... 211 100 WMES Boston, Mass 200 50 WOMT Manitowoc, Wis 248 100 WRBQ Greenville, Miss. 248 100 WSU I Iowa City. Iowa...... 517 500 WmMN Fairmont, W. Va 337 2:0 WOO Philadelphia, Pa 200 100 WRBT Wilmington, N. C..... 219 50 WSUN St. Petersburg, Fia.... 333 1000 WMPC Lapeer. Mich 200 '10 WOOD Grand Rapids, Mich... 236 500 WRBU Cu N. C 248 50 WSVS Buffalo, N...... 219 50 WMRJ Jnmaies, N. Y. City.. 211 111 WO 0 Kansas City, Mo..... 492 1000 WRBW Columbia, C 316 10 Ws AD Syracuse, N.Y 526 250 W MSG New York City 222 250 W O R Newark. N. J 422 5000 W RC Washington. D.C...... 510 500 W T A D c 208 500 WNAC See WB IS WORD Chicago, Ill 203 51)00 WREC Tenn...... 500 500 W7AG Worcester,Cleveland, Mnae. 517 250 W NA D Norman, Okla. 297 500 WOS Jefferson City, Mo 476 500 WREN Lawrence, Kansas..... 246 1000 WTAM Cleveland, Ohio 280 3500 WNAT Philadelphia, Pa 929 100 W OV New York City (day). 265 1000 W RHM Minneapolis, Minn.... 240 1000 WTA0 Eau Claire, Wls. 225 1000 W Omaha, WNAX l'anktop, S. D . 526 500 wo Neb. 508 1000 WRJN Racine, Wis. 250 100 WTAR Norfolk, Va 384 500 WNBF Binghamton, N ...... 200 50 WO WO Fort Wayne, Ind..... 258 5000 W RK Hamilton. Ohio 229 100 WT A W College Station, TeX... 268 500 WNBH New Bedford, Mass... 229 250 W PAP New York City 297 250 WRM Urbana, Ili 337 250 WTAX Streator, Ill. 248 50 WNBJ Knoxville, Tenn 229 50 WP CC Chicago, Ill 526 500 WRNY New York City 297 250 WTAZ Richmond, Va. 248 15 WNBO Washington. Pa 250 15 WPC H New York City (day). 370 500 WRR Dallas, Texas 252 5000 WTBO Cumberland, Did 211 50 W N B Q Rochester, N. Y 200 15 WPG Atlantic City, N. J.... 273 5000 WRUF Gainesville, Fla 204 5000 WTBQ Wilmington, Del 200 100 WNBR Memphis. Tenn 210 500 WPOR See WTAR WRVA Richmond, Va. 270 5000 WT F I Toccoa Falls, Ga 207 500 W N B W Carbondale. Pa 250 5 WPRC Harrisburg. Pa 250 100 WSAI rnclnnntyOhlo(Ltd.) 375 5000 WTHS Atlanta, Ga . 229 100 WNBX Springfield. Vt 250 10 WPSC State College, Pa. (day) 244 500 WSAJ Grove City, Pa 229 100 WT IC Hartford. Conn. 500 .50 W N BZ Lake, N. Y. W PS W Philadelphia, Pa 200 50 WSAN Allentown, Pa 200 100 Permit 282 meters, 50,000 watts. [Saranac 232 10 W PT F Raleigh, N. C. 441 5000 WSAR Portsmouth, R. I 207 250 WTMJ Milwaukee, Wis...... 484 1000 W N E W Norfolk. Va 229 101) W QA M Miami, Florida 242 1000 WSAI Huntington, W. Va.... 517 250 W WAE Chicago, III... 250 100 W NJ Newark. N. J. 207 250 W CAN Scranton, Pa 341 250 WSB Atlanta, Ga 405 10000 W WJ Detroit, Mich 326 1000 WQAO See WPAP WSBC WNOX Knoxville, Tenn...... 535 1000 Chicago, Ill 248 100 WW L - New Orleans, La 353 5000 WNRC Greensboro. N. C..... 208 500 W (IBC Utica, Miss. 220 300 WSBT South Bend. Ind 244 500 526 500 w QBJ Clarksburg, W. Va.. 50 65 WSDA Brooklyn. N. Y 214 500 WWNC Asheville, N. C 526 1000 WNYC New York City WWRL W OA I San Antonio. Texas... 252 5000 WQBZ Weirton, W. Va 211 60 WSEA Norfolk. Va 384 500 Woodside. N. Y 200 100 W OA Lawrenceburg, Tenn.. 500 500 WRAF LaPorte, Ind 250 100 WSGH See WSDA WWVA Wheeling, W. Va..... 258 5000
LIST OF CANADIAN BROADCAST CALLS CFAC Calgary. Alta...... 434 500 CHCT See CKLC CJOC Lethbridge, Alta. 268 50 CKOC Hamilton. Ont. 341 100 CFBO St. John, N. B. 337 50 CHGS Summerside, P. E. I 268 25 CJOR Sea Island, B. C 291 50 CKO W See CFCA CFCA Toronto, Ont. 357 500 CHLS See CKCD CJRM Moose Jaw, Sask 297 500 CKPC Preston, Ont. 248 25 CFCF Montreal. Que...... 411 1650 CHMA Edmonton, Alta...... 517 250 CJRW Fleming, Sask. 297 500 CKPR Midland, Ont 268 50 CFCH Iroquois Falls, Ont.... 500 0 CHML Mount Hamilton, Ont. 341 50 CJSC See CKCL CKSH St. Hyacinthe, Que 297 50 CFCN Calgary, Alta...... 434 1800 CHNC See CKNC CKAC Montreal. Que 411 1200 CKUA Edmonton, Alta 517 500 CFCO Chatham. Ont 248 25 CHNS Halifax. N. S. 322 500 CKCD Vancouver, B. C. 411 50 C K W X Vancouver, B. C. 411 100 CFCT Victoria. B C 476 500 CHRC Quebec, Quebec 341 CKCI Quebec. Que 341 23 C K Y Winnipeg, Man. 384 5000 CFCY Charlottetown, P. E. I. 312 100 CH WC Regina, Sask 312 15 CKCK Regina. Bask...... 312 500 CNRA Moncton. N. B 476 .500 CFJC Kamloops. B. C.... 268 15 CH W K Chllliwack, B. C. 248 - CKCL Toronto. Ont 517 500 CN RC See CFAC CFLC Prescott, Ontario 297 50 CHYC Montreal, Que...... 411 750 CKCO Ottawa. Ont 434 100 CN RE See CJCA CF MC Kingston, Ont. 268 20 CJ BC (Uses several Toronto CKCR Brantford. Ont. 297 50 CNRM See CHYC, CKAC, or CFCF CFNB Fredericton. N. B..... 248 50 Stations)..517, 337 or 312 CKCV Quebec, Que .... 341 50 CNRO Ottawa, Ont 434 500 CFQC Saskatoon, Sask 329 500 CJBR Regina. Sask 312 500 CKFC Vancouver. B. C...... 411 50 CNRQ See CKCV CFRB Toronto. Ont 312 1000 CJCA Edmonton, Alta. 17 500 CKGW BowmanvWe. Ont..... 312 5000 CNRR See CKCK CFRC Kingston. Ont. 268 500 CJCJ Calgary, Alta 434. 250 CKLC Red Deer. Alberta.... 357 1000 CNRS See CFQC CHCA See CJCJ CJGC London, Ont 329 500 CKMC Cobalt. Ont 248 15 CNRT See CFCA CHCK Charlottetown. P. E. I. 312 30 CJGX Yorkton. Sask. 476 500 CKMO Vancouver. B.C. 411 50 C RV Vancouver, B. C 291 500 CHCS Hamilton, Ont...... 341 10 CJHS Saskatoon, Sask...... 329 250 CKNC Toronto, Ont. 517 500 CNRW See CKY LIST OF SHORT-WAVE STATIONS OF THE WORLD .Stations will prefix their calls with their allotted national letters on or before January 1. 1929.
Radio Radio Radio Call BROADCAST STA. Call BROADCAST STA. Call BROADCAST STA. Letters L Ion Letters Location Letters Location
AFRICA HOLLAND AIN Casablanca. Morocco 51.00 SWEDEN PCJJ Eindhoven 31.4 30.000 SKR Constantine, Tunis 42.80 PCKK SAS Karlsborg 52.50 JB Johannesburg. U. S. Africa 32.00 Kootwilk 16.00 SAA Karlskrona 44.40 7L0 4.000 PC LL Kootwijk 18.10 32,000 Nairobi, Kenya 90.00 PCMM SAJ Karlsborg 47.00 The Hague 46.50 SMHA Stockholm 41.00 AUSTRALIA PC PP Kootwilk 16.50 2BL Sydney 32.50 PCRR Kootwijk 37.00 2FC Sydney 28.50 PC TT Kootwilk 21.00 SWITZERLAND 2ME Sydney 28.50 PCuU The Hague 37.00 3AR Melbourne. 55.00 H9OC lierne 32.00 3L0 Melbourne 32.00 ITALY 119X0 Zurich 85.00 and 32.00 GAG Penh, West Australia 32.90 11AX Rome 45.00 LAY Rome 45.00 AUSTRIA IM I Milan 45.00 UNITED STATES 0E1152 Vienna 70.00 EATH Vienna 37.00 KDKA (WBXK) East Pittsburgh, Pa. 62.50 40,000 Vienna 22.20 (WSXS, WSXP-portable) 42.75 25.40 BELGIUM THIS list of the short -wave broadcast KEJK (W6XAN) Los Angeles, Calif 105.90 250 EB4A2 Brussels 42.00 300 stations throughout the world is not KEWE Bolinas, Calif 14.10 complete, although we have endeavored to K FPY (W7XAB) Spokane, Washington 105.90 100 CANADA list every station of whom we have heard KFQU (W6XBH) Holy City Calif. 31.00 50 CF 1)rummondvllle, Quebec KFQZ (WGXAL) Hollywood, Calif 108.20 50 32.00 reports ; since cases CJRX Winnipeg, Man 25.60 2,000 in many reliable in- KFVD (W6XBX) Culver City, Calif 105.00 50 formation about the programs, wavelength KFWB (W6XBR) Los Angeles, Calif 105.00 50 COSTA RICA and power of the stations cannot even be 40.00 obtained from the stations themselves. KFWO (W6XAD) Avalon, Calif 53.07 100 NRH Heredia 30.30 711 KCER (WSXBV) Long Beach, (See page 654) Calif 48.86 DANTZIG KGB San Diego. Calif 65.18 EK4ZZZ KGDE Barrett, Minn 40.00 50 Dantzig 40.00 KGO (W6XAX, WSXN) San Francisco, Calif 10 to 40 10,000 KW (W6XAU) Los Angeles, Calif 104.10 50 DENMARK JAPAN KJ BS (W6XAR) San Irancisco, D7MK Copenhagen Calif 61.00 50 32.0.5 500 JFAB KJR (W7XC, W7XO) Seattle, Washington 105.20 250 DIRL Copenhagen 42.12 and 84.24 250 Taipeh. Formata 39.:0 'BBB Ibarakiken (Illmslo) 37.:0 2,000 KMOX St. Louis, Mo. 49.00 15 J tPP Tokio 20.00 KMTR Los Angeles, Calif 108.20 250 ENGLAND KNRC (W6XAF) Santa hlonles, Calif 5S W Chelmsford JKZB Tokio 20.00 108.20 100 24.30 15,000 JOAK KNX (WSXA) Los Angeles, Calif 107.10 100 2N M Caterham 32.50 Tokio_. 30.00, 60.00, 35.00, 70.00 500 KOIL (W9XU) CBS IAA Iwatsukl 40.00 Council Bluffs. Iowa 61.06 500 Rugby 24.40 KWE -KEWE Bolinas, Calif 14.10 JAVA KWJJ (W7XAO) Portland, Oregon 53.54 100 FINLAND WAAM (W2XBA) Newark, N. J 65.18 50 Ilelsingfors (Helsinki) 31.50 Malabar 33.00 ANE Bandoeng 31.86 and 33.00 WABC (W2XE) Richmond Hill. N. Y 58.50 500 FRANCE ANF Dtalabar 56.00 WAJ Rocky Point, N. Y 22.48 FBGC ANN Malabar 17.00 WBRL (W1XY) Tilton, N. H 109.00 250 Parts ("Radio LL") 61.00 500 WCFL Chicago 37.24 F8AV 87.0000 Batavia 4650 Ill 0. Radio 500 WCGU (W2XBH) Brooklyn, N.Y 54.00 A Vitus Parl.9Wnt 1.500 MEXICO WCSH (W1XAB) Portland, Maine 63.79 250 Eiffel Tower Paris (time signals) 32.00 YR 250 XC51 Mexico City 44.00 WC Pontiac,Mlchngan 32.00 75 Lyons ("Radio Lyon") 40.20 WEAL Rocky Point, N. Y 22.48 30.75 MOROCCO WEAO (WBXJ) Columbus, Ohio 54.02 25 Ì yosn 00 3,500 LAG Y (W2XAF) Schenectady, N. Y..... 31.40 Nancy 15.50 AIN Casablanca 51.00 (W2XAD) Schenectady. F W 4 Ste. N. Y 21.96 Assise 24.50 5.00 NORWAY WHK (WBXF) Cleveland, Ohio 66.04 500 GERMANY LCHO Oslo 33.00 WJR -WCX (WBXAO) Pontiac, Michigan 32.00 AF I Koni swusterhausen 14.00 LcN Bergen 31 25, 30.00 W lZ New Brunswick N. J 43.45 AFL Hamburg 70.00 and 52.00 WJZ (W3XL) AFT Konigswusterhausen New York. N. It 59.96 30,000 14.00 U. S. S. WLW (W$XAL) CInclnnati, Ohio 52.02 250 AFU Konlgswusterhausen 14.00 R. (RUSSIA) AFK RDRL WNAL (W9XAB) Omaha, Neb 105.00 50 Berlin (Doberltz) 67.65 WNBT Elgin, III. (Time Signals) 35.50 500 HEA Nauen 11.00 RDW Moscow 83.00 AGC RFat Knabarovsk (Siberia) WND "" Ocean Township, N. J 46.48 Berlin 17.20 70.20 12,000 W OR (W2XAQ) Kearny, N. J AG1 Nauen 56.70 RFN Moscow 50.00 65.40 50 RA19 woWO Fort Wayne, and 22.80 1,000 AG Nauen 11.00 Tomsk (Siberia) 37.00 WRNY (W2XAL) York, LA berg New N.Y 30.91 500 WSM (4XD) . Nashville, Tenn 31.43 POF Nauen 11.00 SPAIN POZ WTFF Mt. Vernon, Va 56.00 Nauen EA M Madrid 30.70 W2XC Rocky Point (transatlantic tgart 41.00 EA R55 Barcelona phone) 16.02
www.americanradiohistory.com 65S Radio News for January, 1929
I:ABï1AT'OiteS, 17(:%92%
ADIO manufacturers are invited o send to RADIO NEWS LABORATORIES meats. No "write -ups" sent by manufacturers are published in these pages. R samples 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 If, 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- to modern radio engineering practice, they will each be awarded a certificate warded prepaid, otherwise they cannot be accepted. Apparatus ready for, or of 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 "IVhat'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 be returned to the manufacturer with suggestions for improve- formed on request if any article has been issued a Certificate of Merit.
FIXED RESISTORS was submitted by this manufacturer. It is not the optimum operation of the screen -grid tulle. condenser, as are When properly shielded, very great amplification The "Eminent" resistors shown here, submitted provided with a compensating the others. (due to the low -loss construction of the coil) was by Paul Zollner, Berlin S14, Kommandanstenstr. RADIO NEWS LABORA- obtained over the waveband from 200 to 550 meters; 51, Germany, are of the grid -leak type. The AWARDED THE is TORIES CERTIFICATE OF MERIT NO. 2456. the secondary was tuned with a 350 -mmf. condenser. resistant material is a carbon composition which Various degrees of increased selectivity, with a corresponding decrease in amplification, were ob- TUNING CONDENSER tained. The "Type 320" tuning condenser shown, manu- AWARDED THE RADIO NEWS LABORA- factured and submitted by Silver -Marshall, Inc., TORIES CERTIFICATE OF MERIT NO. 2462. 846 West Jackson Blvd., Chicago, Illinois, is of low -loss construction, with plates shaped to give a modified SLF tuning curve. The condenser has 5% of its rated value; FIXED CONDENSER coated in an even layer on a -inch porcelain rod a maximum capacity within h the measured minimum capacity is 2 mmf. The The "Type 1460" fixed condenser shown, sub- 1 inch long; the latter is provided at each end with to the stator plates are accurately spaced and rigidly sup- mitted by the Aerovox Wireless Corp., 70 Washing- brass springs which are in turn soldered riveted to brass end caps. The resistance element is pro- ported by hard- rubber strips which are ton Street, Brooklyn, N. Y., is of the molded tected hard- different the metal and plates of the condenser. The con- bakelite -mica type. It is, approximately, only 1K. by a molded rubber tube; -inch and resistance by various widths denser is provided with a rotor inches long, Winch wide and 7/32 thick; values are obtained metal sub -panels. of spiral grooves cut out of the composition. The stop, which serves also to hold has been designed for mounting on top. assembled resistor is inches long and Winch the end plates together at the Special insulated holes, drilled -hole- end in diameter, and will fit easily into a standard The condenser is of the one at each of the condenser, resistance mounting. Samples of different values mounting type; the back-of-panel allow the passage of 6/32 were submitted for test, and their resistance were space occupied is approximately screws. Tinned terminal lugs found within 10% of the rated values. 3 inches square. The plates and are provided at each end of condenser end -pieces are die - the condenser for soldering though, if desired, AWARDED THE RADIO NEWS LABORA- The TORIES CERTIFICATE OF MERIT NO. 2451. stamped from hard aluminum alloy. machine screws may be used for connections. AWARDED THE RADIO NEWS LABORA- condenser is made in various capacities from 40 TORIES CERTIFICATE OF MERIT NO. 2457. to 3000 -mmf. (.00004 -to .003 -mf.) with a rated VARIABLE. CONDENSERS tolerance of 10% of the nominal capacity; the 150 -mmf. sample submitted for test has a capacity In the triple-gang condenser (Type No. 1703) RADIO -FREQUENCY COILS shown, submitted by the Pilot Electric Mfg., Co., 5% below the nominal rating. The "AC17" R.F. coil submitted by the Ham - AWARDED THE RADIO NEWS LABORA- Inc., 323 Berry St., Brooklyn, N. Y., each stator 33rd section is provided with a small compensating marlund Mfg. Co., Inc., 424 W. Street, TORIES CERTIFICATE OF MERIT NO. 2463. of mica- spring type, with a maximum New York, N. Y., has been designed for use either condenser the as an coupler capacity of 20 -mmf.; which permits of balancing as an antenna coupler or interstage for 226- and 227 -type A.C. tubes. It is of low - the circuits to compensate for capacity changes secondary POWER RESISTORS introduced by the wiring. The maximum capacity loss construction; the 84 turns of the a thin cylinder of each unit was found within 5% of the rated are space -wound and supported by The "Truvolt" resistor shown, submitted by value, .00035mf. and the minimum was equally Electrad, Inc., 175 Varick Street, New York, N. accurate; the individual sections of the gang con- Y., is designed for use in "B" power units, or a heavy -duty resistor is needed. The denser match to within 1 %. The plates are shaped wherever to give a capacity variation-characteristic midway resistance element consists of nichrome wire wound is between those of the SLF and the SLAV types. on a core of asbestos which, in turn, spiralled The over a core of enameled copper wire; this assembly stators are supported by molded bakelite strips, threaded one of which is used to mount the compensating is then wound around a grooved or condensers. The instrument is designed for either isolantite tube, 2 inches long. This construction one -hole panel mounting, or fastening to the exhibits greater cooling surface for the dissipation sub- panel. The rotor is the floating type, allow- of heat. The unit is assembled in a special of a lever ing interchange of shafts; the removable shaft mounting support, on which is provided varying the resistance. The mounting support is 7 inches long. The condenser requires a back - of celluloid. Green silk- covered wire is used for contains a bushing for one -hole panel mounting; of -panel space 3 %x6 inches; it is arranged to both the primary and secondary windings. The sub - allow either clockwise or counterclockwise tuning. a bracket also is provided for baseboard or primary of 30 turns, tapped at the 7th and 15th, panel mounting. A perforated metal housing, to AWARDED THE RADIO NEWS LABORA- is wound on a smaller sleeve of celluloid, which TORIES CERTIFICATE OF MERIT NO. 2454. protect the resistance element from damage, is is fastened inside the secondary form at its filament fitted around the end brackets of the mounting end. The coil assembly is secured to a strip of support. The measured resistance of the 2000 -ohm bakelite, at the lower end of which is a bracket sample submitted for test was 1960 ohms, and it for vertical mounting of the coil; the leads of the varied less than 2% front its measured no -load primary and the filament end of the secondary value under a load of 25 watts for one hour. are fastened to a five -lug terminal strip for con- AWARDED THE RADIO NEWS LABORA- venient wiring into the circuit. When used in TORIES CERTIFICATE connection with a 350 -mmf. tuning condenser, this OF MERIT NO. 2464. coil will tune over the broadcast waveband from to meters. The same manufacturer submitted also a "Type 200 550 TRUbOLT" AWARDED THE RADIO NEWS LABORA- LLECIRACroc 1702" twin or two-gang condenser, otherwise simi- OF MERIT NO. 2461. lar to the instrument described above. The capacity TORIES CERTIFICATE values were found of the same accuracy as those The "Type SGT17" R.F. coil submitted by the of The plates are of use as No. 2464 the three -gang condenser. same manufacturer has been designed for No 2465 the "centreline" type, allowing even separation of an interstage coupler for 222 -type (screen -grid) stations throughout the entire broadcast band. Either tubes. Its general appearance and construction is The "Type D -80" fixed power resistor shown, one -hole panel mounting or sub -panel mounting, the same as that of the previous item, except for submitted for test by the same manufacturer, em- as preferred, is possible; the sub -panel space re- a larger primary winding. The primary winding, bodies the same construction as the variable "Tru- quired is 4- 11/16x3% inches. 100 turns of fine green -silk -covered wire, is ap- volt." The resistance element is wound on a AWARDED THE RADIO NEWS LABORA- proximately I ) inches in diameter and placed grooved isolantite tube 6 inches long; at the ends TORIES CERTIFICATE OF MERIT NO. 2455. inside the secondary at the filament end. The are metal clamps which serve both to fasten the "Type 1701," single unit of the same capacity design of the special primary winding allows the wire in position and -to provide a means of obtaining and general construction as those described above, tapping -off of any desired plate -load impedance for good contact with the resistance element. A center
www.americanradiohistory.com Radio News for January, 1929 659
tap is included in the sample submitted for test. duction over the audio-frequency range with ample made by the same manufacturer, has been designed The resistance at its rated load of 75 watts. for volume. for use as the second -stage transformer when the one hour exhibited a change of less than 2% from No. 920 is employed in the first stage. The wind- the rated value of 8000 ohms. ing ratio of this transformer is 1 : 6%, and AWARDED THE RADIO NEWS LABORA- the frequency characteristic falls off below X100 TORIES CERTIFICATE OF MERIT NO. 2465. cycles; when it is used with the No. 920, the over -all frequency- characteristic will be nearly flat. This transformer has been especially designed to VARIABLE RESISTORS serve as the input to a 250 -type power stage, The "Tonatrol Type WS" variable resistor, sub- when the detector's voltage output is low. Its mitted by the same manufacturer, is designed for physical dimensions are the same as those of the use as a volume control and incorporates a filament other transformers above described. switch. The measured resistance is 0 to 500,000 AWARDED THE RADIO NEWS LABORA- ohms, with smooth variation throughout its range. TORIES CERTIFICATE OF MERIT NO. 2480. Contact with the resistance' strip is made by a special contact element, which consists of a spaced The "No. 922" output transformer, submitted is winding of wire on a fiber strip; this winding for test by the same manufacturer, has been de- split on one side, isolating each individual turn. signed as an output transformer for the 112 -, 171 - The resistance and contact elements are then as- or 210 -type power tubes. The inductance of the sembled between a bakelite outer ring, which serves secondary is of such value as to insure the proper also as a protection to the resistance element, and operation of the usual horn or cone -type reproducer. a central disc, which also carries the bushing for The primary winding will carry safely 40 milli- one -hole mounting. The bushing is provided with AWARDED THE RADIO NEWS LABORA- amperes, and the core is of such size to prevent a shaft, b.,- h. control knob, and an arm of spring TORIES CERTIFICATE OF MERIT NO. 2475. saturation under that current; although the manu- facturer recommends that the plate current should not exced 20 milliamperes. When it was used in A.F. TRANSFORMER the plate circuit of a 171 -type power tube excellent The "Technica" A, F. transformer shown here, reproduction was obtained. submitted by Radio Vertriebs Gesellach, Vienna AWARDED THE RADIO NEWS LABORA- IX, Porzellang 14, Austria, has a winding ratio TORIES CERTIFICATE OF MERIT NO. 2481. of 1 : 3. Mechanically and electrically, this trans- former is well built; and, when it was used with a 201A -type tube, good amplification was obtained A.C. ELECTRIC RECEIVER from 160 to 8,000 cycles. The coil core and are The "Model 7-70" radio receiver shown, sub- enclosed in a molded brown bakelite housing and mitted by the Bremer -Tully Mfg., Co., 520 So. are hermetically sealed in position by a resinous Canal Street, Chicago, Illinois, is of the all -electric insulating compound. The base dimensions for type and operates directly from 110 -volt 60 -cycle No. 2466 (above) house current; it comprises three 226 -type tuned R.F. stages, two 227 -type (detector and first A.F.) No. 2467 (right) and a 171A -type push -pull last stage. A full -wave with rectifier of the 280 type, with output well filtered, metal designed to maintain constant contact supplies the various rotating or in "B" voltages; the filament the wire contact element, whether current is supplied The filament switch, contained from special windings of the any fixed position. power transformer. A single tuning control operates in the base of the resistor, is operated by a portion four tuning arm which applies pressure condensers which are ganged on a of the variable- contact single shaft. The small -field inductors, which are releases a small plug of insulating material. or partially shielded, are mounted directly below The latter opens or closes the switch to which two their respective tuning condensers, in individual shielded lugs extending from the base provide connection. compartments. switch is in the "off" position when the The tuning dial is of the drum The type; a trimmer variable arm is at zero resistance. or compensating condenser for the antenna i5 provided, directly below the scale AWARDED THE RADIO NEWS LABORA- mounting are 3 by .3 inches, and the height is window. A knob for volume control is provided TORIES CERTIFICATE OF MERIT NO. 2466. 2i5 inches. at AP" has designed for the left of the scale window while that fin- The "Tonatrol Type been AWARDED THE RADIO NEWS LABORA- operating use as a volume control or panel -mounting resistor, TORIES CERTIFICATE OF MERIT NO. 2476. the ganged condensers is found on the from which a variation of 0 to 10,000 ohms may he obtained, and is combined with a 110 -volt snap switch for power control. This product is similar A.F. TRANSFORMERS in construction to the " \\'S" type except that the The "No. 900" audio- frequency transformer, power switch is fastened to the resistor's base by submitted by the Remler Division of the Gray and a special bracket and operated by a pin located Danielson Mfg. Co., 260 First Street, San Fran- on the variable arm. The snap switch is in the cisco, Calif., has a winding ratio of 1 : 3.A, and "off" position when the resistance is at zero value. has been designed for use as a first -stage trans- AWARDED THE RADIO NEWS LABORA- former when preceded by a 201A -type detector, TORIES CERTIFICATE OF MERIT NO. 2467. and with a 201A or 112 as the first stage. The transformer is well built mechanically and electri- right. Two panel switches are provided, one con- VACUUM -TUBE DETECTOR cally, giving a factor of amplification almost con- trolling the power and the other acts as an addi- The Model UN -200A" vacuum stant from 32 to 5,000 cycles. The core and tional volume control by switching out the first tube shown, submitted for test winding are enclosed in a die -stamped iron housing audio stage. The receiver and power unit are by the Prexto Manufacturing and sealed hermetically in position by insulating. assembled on a cast-aluminum chassis, which is Company, 676 Euclid Street, compound. The base dimensions required for enclosed within a polished walnut cabinet of pleas- Beaumont, Texas, is a special mounting are 254 by 3 inches, and the height is ing design; its actual size is 21 inches long, 12 detector with a standard UX- 4 inches. inches deep and 10 inches high. A 10 -foot exten- type molded -bakelite base. The AWARDED THE RADIO NEWS LABORA- sion cord is provided for plugging into the light characteristics of this tube were TORIES CERTIFICATE OF MERIT NO. 2477. receptacle, and another to make the ground con- found those of standard tubes of nection; while that to the aerial is made by a the 200A type; so that a grid The "No. 901" audio -frequency transformer, binding post. This receiver is sufficiently sensitive return to "A-" is required. Its submitted by the same manufacturer, has a winding and selective, and gave excellent reproduction over operation as a sensitive and ratio of 1 : 3 and is designed for use as a the audio range. powerful detector was found second -stage coupling transformer, with a 112- or AWARDED THE RADIO NEWS LABORA- satisfactory. 171 -type tube in the second A.F. stage. When TORIES CERTIFICATE OF MERIT NO. 2482. AWARDED THE RADIO it was used in an amplifier in which the No. 900 NEWS LABORATORIES CER- transformer was employed in the first stage, a flat TIFIC.\TE OF MERIT NO. frequency -characteristic from A.C. ELECTRIC RECEIVER 2469. approximately 32 to 5,000 cy- The "Balkite Model. A" A.C.-operated receiver, cles was obtained. The physi- submitted for test by the Fansteel Products Co., cal dimensions are the same North LINEN DIAPHRAGM LOUD SPEAKER of Chicago, Ill., operates directly from the as those of the No. 900. house -lighting circuit on 110 volts, 60 cycles. Five The "Model B" loud speaker, submitted by the AWARDED THE RADIO 227 -type and two semi-power (112A-type) tubes Browning -Drake Corp., Cambridge, Mass., is . of NEWS LABORATORIES are employed, in three stages of radio frequency, the single -linen- diaphragm type. A balanced -arma- CERTIFICATE OF MERIT detector, a transformer-coupled first stage of audio ture unit of excellent mechanical and electrical NO. 2478. frequency, and a push -pull power stage. The design and construction is supported by cross pieces The "No. 920" audio -fre- attached to the wooden frame of the speaker. The quency transformer, made by apex of the linen diaphragm is fastened to the the same manufacturer, has driving pin of the unit, stretched tightly to the been designed for use in am- edges of the wooden frame, and tacked in place. Nos. 2477 -78 -79 -80-81 plifiers where greater gain After the linen is stretched it is "doped" several is desired; this transformer times in order to produce a tighter and more rigid has a winding ratio of 1 : 4 %. The frequency- surface. The diaphragm is 24 inches square and characteristic of this transformer is such that, at its depth is approximately 2 inches at the apex. the lower end of the audio range, slightly greater The wooden frame, of walnut finish, is 28 inches amplification is obtained. The physical dimensions high over all, 24 inches wide and 8 inches deep. are the same as those of the Nos. 900 and 901. receiver is of chassis construction; the coils (of The back is enclosed by a stiff board in which AWARDED THE RADIO NEWS LABORA- small -field type) and condensers (which are ganged there is a circular aperture to allow adjustment of TORIES CERTIFICATE OF MERIT NO. 2479. to a single control) are completely shielded. The the unit. This speaker gave almost equal repro- The "No. 921" audio -frequency transformer, (Continued on page 703)
www.americanradiohistory.com 660 Radio News for January, 1929
. The Radio Constructor's Own Page Wherein Custom and Home Set Builders and Experimenters All Over the World Swap Experiences and Suggestions About Hookups and Accessories PREFERS EXTRA TUBE A CONVENIENT SPEAKER ADJUSTMENT si0- Editor, RADIO NEWS: Editor, RADIO NEWS: Having just read Mr. J. G. Miller's suggestiol The desirable feature of the linen -diaphragm type i as to installing a phonograph switch -over (which of speaker is that it is nearly as good as the converts the detector tuhe into the first audio stage modern dynamic, and at a cost considerably less; in the November RADIO NEWS, I would like to while it is readily constructed by almost anyone cap- able of using a few simple tools. It can be made al-- most any shape or size to fit certain unused space in the room, or to fit into any console. I am at present engaged in building a round one, 24 inches in diameter and 6 inches deep. The wood is laid on in segments, glued, and turned in a large lathe. This makes an exceedingly solid frame. The accompanying photographs show an im- provement I have made in the speaker which is, so far as I know, original with me, as I have not heard or read of it elsewhere. The frame of the speaker illustrated is 18x24 inches, 5 deep, and made of I§ -inch pine; corners lapped and nailed, with metal corner braces screwed inside. The back frame is 1'''%x1% stock, ash; use any- thing a little harder and more rigid than soft pine. The cloth, front and back, is airplane linen; a thinner and lighter grade has been recommended for the front, but I have no experience of it The back frame is located between guide strips and can be pulled back until the cloth is perfectly -tight; it is held in place by a -inch round brass pins, running through the sides of the frame from Mr. Lahmann's phonograph pick -up is provided with a stage (A.F.) of its own to use before his ,:,:::1,:/1::1::1:4:11:1:::1::::::: 1::::,,::::1::1:,:1:31:1.::4:1::1::1 ::.::.:::.:::::::.1:::::::::,:::1::,,:1::,::1::::,:::.: set's amplifier. The reader will see that a D.P. D.T. switch would give also a choice of R.F. for information not given and pick -up filament circuits. INQUIRIEShere should be sent, not to RADIO NEWS, but to the constructor direct-but he should point out that the adoption of this idea may cause NOT be asked to furnish data already This rant view of Mr. Ulrich's speaker shows trouble. published, here or elsewhere, or for instruc- the holes in the side frames, which admit stop - All radio engineers are doing their utmost today tions that an experienced builder should not pins to regulate the adjustment of the linen to keep R.F. grid leads as short as possible, and need; for this is not a beginners' depart- diaphragm's tension, as explained. run them direct to the connection. In the pro- ment. Courtesy demands that such requests posed hook-up, they are led to the switch and should be accompanied by postage; as they center of the cloth and work a small hole back; and it is readily easy to see what will are often very numerous. Reply coupons through without happen when the points of the jack begin to can be obtained from the postotfice for cutting or breaking any threads of the linen. corrode. international inquiries. On the other hand, Fasten in the apex with an extra washer cut out I submit a drawing of a hook -up which will save of airplane cloth, which will help to protect the readers who solicit general correspondence diaphragm against cuttting. Draw the diaphragms the same purpose and will give no "after effects;" to bear own share. must expect their together and pull back the small frame until you in the hope that it will be taken, not merely as This department is for free discussion to a possible to the can place the holding pins at about the first a criticism, but as assistance the extent that space permits; but RADIO experimenter. holes, or perhaps the second, without undue strain. NEWS accepts no responsibility for the Then give the cloth about five coats of airplane FRANCIS J. LAUMANN, opinions of readers as to the relative merits 309 No. Noble St., Indianapolis, Indiana. dope, drying well between applications (keep it of apparatus and circuits. away from fire!). Center and mount the driving Letters describing good results, but which unit on the back of the small frame; see that the do not explain the system used, are unsuited pin is centered squarely with the apex, and then for publication; as they entail too much draw back the small frame, one side at a time, needless correspondence for the editors and as far as it will go. Pin it in place and then the contributors. Give the details the first tighten the thumb nuts on the long rod until the time. assembly is solid. Lastly, tighten the apex on the unit's driving rod -it must always be loosened li before an adjustment of the diaphragm is made. Frame and cloth may be decorated to suit, remem- the outside, through holes bored about '/s -inch apart. bering that nothing should be left loose to vibrate. The cloth is stretched back one notch at a time, as VICTOR A. ULRICH, required. When it is as taut as desirable, and 97 Cook Street, San Francisco, Calif. the sidepins are holding it, the thumbscrews on the long h -inch rod are drawn tight, compressing the sides of the large frame against the ends of THE LOVELESS AERIAL AGAIN -OR YET the smaller one and holding the assembly solid. Editor, RADIO NEWS: The center of the rod is tied down to a screw I find that by connecting the outside coil of a eye so that it will not vibrate; the rod must be Loveless antenna to ground only and leaving the far enough below the center to clear the loud- ground connection on the set open, I get very speaker unit. It might even be better to use two fine results. I am using a 6 -tube set with two rods, one above and one below. The side pins, it stages of R.F.; storage "A" battery and Sterling should be understood, do not go into the ends of 135 -volt power unit. the small frame, but just in front of them, so that J. S. MARTIN. the tension of the cloth holds the frame firmly 2626 Euclid Avenue, Cleveland, Ohio. against them. They extend through about 4 -inch on the inside to form a sufficient stop for the frame to rest against. TOOK THE PRIZE In building the frames, lap, dovetail or miter the Editor, RADIO NEws: corners to make a perfectly solid joint; leave I was so impressed with the possibilities of your nothing loose to vibrate. There is not much to "All -Wave Circuit" in your April, 1928, issue, be gained by making it larger than 24 inches square; that I have been working steadily on it. I was this will cover the broadcast frequencies perfectly. so pleased with the result that I entered it in the It is from 5 to 8 inches deep, according to size. show of the Montreal and District Radio Club The small frame is made with its two crossbars held here recently. I am pleased to say that I enclosing an opening about eight inches square; was awarded third in class A; which I think you
and of such length that it fits closely, but not will agree was a creditable performance in such too tightly for adjustment, inside the large frame. good company. I carried out the idea with panel, This rear view of Mr. Ulrich's linen-speaker Tack the linen on both frames, stretching it sub -panel and all parts, including Phasatrol and shores very clearly the adjustments described. tightly, with tacks about one inch apart, as the Tonatrol, in black bakelite; every part bolted firmly The assembly is held tight by cramping the strain on the cloth is considerable. Place the to sub -panel with brass bolts and nuts. This, large frame on the cross -pieces with the and small frame between the centered guide strips with Ambassador push -pull transformers in blue and of the threaded rod, at the right. . on the sides of the large frame; find the exact (Continued on page 691)
www.americanradiohistory.com Radio News for January, 1929 661
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Conducted by C. W. Palmer 117e cannot supply blueprints of manufactured apparatus; only grams, etc., C. O. D. Please read the instructions and do not RADIO NEWS blueprints, which should be asked for on the cou- use pencil or postal cards. RADIO NEWS sells no apparatus, does pon printed elsewhere. We cannot send magazines, books, dia- no custom building, and can not advise "the best set to buy."
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 in each letter. If you inquire concerning a circuit Many fetters are not readable. Simple questions will be answered free; which is not a standard, published one, enclose a diagram to save delay.
Wag
REPAIRING "B" POWER UNITS set does not operate well, the trouble may be due circuits.) You should hear a click on making (2320) Mr. J. R. Cliffman, Rochester, N. Y., to the development of a defect in a by -pass con- contact; and also, on testing, between either of the writes: denser, or to a faulty construction of the unit, filament terminals on the rectifier socket and the (Q.) "I am a custom builder and repair man. omitting a condenser where it is needed. negative terminal of the unit. The clicks from In repairing sets I often encounter trouble in 'B' In testing for these breaks the following method both of these binding posts should be of equal power units and, up to the present, I have never strength; if one is stronger than the other, the seen any information for locating trouble in these trouble is generally due to a defect in one of the units. This is especially true of the units using buffer condensers (CS and C6 in the diagram). the gaseous rectifiers; since there is no filament C+ rP-4- If no click is heard from one terminal, either the to tell when the tube is operating correctly." -11r-1 secondary winding of the transformer is open or "1 am also at a loss when one tap of the ¡ the center tap does not connect to the negative unit will not supply any current, while the rest terminal. of the power unit works satisfactorily. I would The secondary winding of the transformer can appreciate any information that you can give me QL be checked by first removing the tube from the in this matter." Tc socket and then connecting the primary of the (A.) Although there are few causes for trouble power transformer to the line through a 25 -watt in the standard "B" power units, trouble does 110 -volt lamp, in series with one of the leads. occur sometimes; and a few simple tests will -A- If the secondary is in good order, the lamp will enable the experimenter to locate and correct it. not glow at all, or a very dull glow may be seen. The diagram of the most common type of unit, Ct If the lamp glows brightly, either the secondary employing the gaseous -conduction type of rectifier Pll is broken down or one of the buffer condensers is f 'úü-1 short -circuited. On replacing the rectifier tube tube, is shown in Fig. 02320. This diagram will I 1 be followed in making suggestions, although other in its socket, the lamp in the primary lead will types of units can also be tested by the same glow brighter. The buffer condensers should be methods. Test with set connected: disconnected, in order to test them separately. _ The test described above will also serve to gauge No Voltage at a Given Tap the operation of the gaseous tube since a poor tube will not show in the light If no voltage can be read with a high- resistance an increase of the lamp. A gaseous -conduction voltmeter from one of the taps of the unit, the rectifier tube will usually logical point to look for trouble is in the resistor -B- give about 1,000 hours of service before trouble is encountered. When the tube becomes old, the bank. Then, if the trouble is not located, the Q-2321 - parts should be tested back from this point until output voltage gradually falls off and it is neces- the defective part is found. When making the sary to keep turning up the resistors to maintain the tests, first look at rectifier tube to make sure A correct voltages. When the resistors can no the resistance in the tuned circuit, as at A, longer that it does not appear to be damaged. -then broadens the tuning; while one outside it, as be adjusted to give the required voltage, a new tube must be make sure that current is flowing through the at B, does not affect selectivity, but "damps" used. The gaseous tube becomes primary of the transformer. oscillation through the tube capacity, Ct. quite warm when operating correctly and this fact An open- circuited or burnt -out resistor will result often serves to indicate whether or not the tube in no current flow at the tap that it controls; for is in good condition. instance, if the resistor Rl in Fig. 02320 becomes may be used. Disconnect the power supply from Excessive Hum open -circuited there will of course be no voltage the unit; then connect a pair of phones, with a at the "P,+Det." tap. On the other hand, if R2 battery in series, between the plate terminal of This may be caused by a filter condenser's be- is broken, the detector voltage will immediately the rectifier tube and the positive output terminal. coming open- circuited, or by an open lead to one increase. In receivers of some types this would (Remove the rectifier tube before testing these of the condensers; it might also be due to a short- result in a decrease of the volume; while sets with regenerative detectors would get out of control. The simplest method of locating a defective resistor is to connect a high- resistance voltmeter to LI L2 each tap in turn. A meter of this type is almost O B+ essential when a unit of this type is used; both -r-000P- 00óP PWR for measuring the output, in order to get the best results from a set, and for testing defective R1 R3 units. In the absence of a voltmeter, a 15 -watt 220 -volt electric -light bulb may be employed; it 8+ should be connected like the voltmeter, between AMP the negative terminal and each of the positive C3 terminals in turn. It should glow a dull red on the high and intermediate taps and, with the de- tector resistor turned all the way in, a dull glow 8+ should be obtained on this tap also. If the detector C1 C2 DET. lights the bulb with brightness equal to that ob- tained from the other taps, the 10,000 -ohm resistor C6/ C7 (R2) is open or defective. No Voltage from any Terminal OB This trouble may be due to an open circuit in Q-2320 C4 R2- the windings of the power transformer or in one of the choke coils; or it may be due to a broken - down condenser in one of the filter circuits, ór to The circuit of a typical "B" power unit employing a gaseous rectifier tube. A brief study of a broken wire. this will determine what irregularity in the voltage at any terminal means. If a resistor breaks If the tap voltages are found correct and the between a higher and a lower voltage, the voltage above increases; that below is cut off.
www.americanradiohistory.com 662 Radio News for January, 1929
circuited choke coil or to the usual causes of hum in the receiver itself. The action of the choke coils may be tested by short -circuiting each of .006 them in turn. MF 4'M'F.^^ If both chokes are functioning .correctly, the hum 171 -A will be increased when either is short -circuited. If no difference is noted when one of the chokes is shorted, the connections should be checked and, if they are found correct, a -new choke should be inserted. In some installations, although the power unit is in apparently good working order, the hum will be objectionable. In such case, it -0 may usually be reduced by increasing the size of B+ the filter condensers, and C3. DET. A.F. C2 CHOKE The electrolytic condenser is particularly adapted R to this purpose because of the high capacity of condensers of this type, compared to their size. A-C+ The electrolytic condensers should be used to re- place the paper condensers or connected in parallel A+ 111111111=111INIMI MI with the filter condensers already in the unit, if this is more convenient. 8+135V.-
1 MF. GRID SUPPRESSORS B+180V.o (2321) Mr. A. B. Webster, Washington, D. C., C-11/2V. o writes: (Q.) "I have noticed that quite a number of sets are using resistors connected in the grid cir- C-40t/2V.o Q- 2323 A cuits, to prevent them from oscillating. It appears to me that this would reduce the amplification and efficiency of the set a great deal. Is this correct, This resistance- coupled amplifier with two high -mu tubes in the first two stages is designed for or is my statement incorrect? Can you explain high quality and ree!l adapted for television work; the chokes prevent "motorboating." the action of these resistors ?" (A.) The "grid suppressor" is a very much mis- understood device. Some people class it with the current developed by the normal regenerative Fig. Q. 2321.1) connected in series with the tuning the "losser" methods of controlling oscillation in action of most R.F. circuits. This current, coil and condenser (L and C) will accomplish R.F. amplifiers, but strictly speaking it is not in which starts in the plate circuit of each tube, this wasteful purpose and, incidentally, will tend this category. In "losser" systems, the resistance flows back into the grid circuit through the small to broaden the turning very considerably. If we move this resistor out of the actual tuned circuit, and place it between that circuit and the grid of the tube (Fig. Q.232113), its action becomes altogether different. It is now directly in the 0.1 T0.25 MEG. .006 TO A.F. CHOKE path of the troublesome feed -back current which .02 MF. T1 4 MF is coming through the tube capacity Ct, and limits VI , V2 the flow of that current before it gets to the r. oscillatory circuit LC. Y p, Notice that the resistor, not being in the oscilla- CI C2 I tory circuit proper, does not affect its tuning characteristics in the least. The "suppressor" is í1 actually in series with the almost infinitely high B+ L.S. resistance formed by the grid and filament in the its is of DET. tube, and few hundred ohms resistance 5 2 MEG. little consequence. OHMS- -O R3 The value of the grid suppressors in any receiver IO OHMS,, R1 R2 depends, of course, on the tendency of the circuits to oscillate. The purpose of the resistors is not A-C+ c to eliminate entirely the feed -Lack current, but merely to suppress it, as their name indicates. A+ o A limited amount of feed -back is highly desirable, B+ 135 A. as it increases the sensitivity of the receiver a TO 180 V.j great deal. Suppressors usually range in value between 200 C-401/2 V, o and 1,000 ohms. It is practically impossible to B+ 22I/2 V. O recommend specific values for particular sets or Q-2323 B circuits; the only thing to do is to try different values until the receiver becomes stable ill oscilla- This tion. amplifier, with the amplification factor of a screen -grid A.F. tube, will give an extremely The resistors must be of the non -inductive type. flat frequency curve. R1 is tapped for the right grid bias; R2 is about 6 ohms. Those sold for the purpose are identical in appear- ance with grid leaks, and fit in standard clip - mountings. of the tuned circuits (comprising the secondaries capacity formed by the grid and plate elements of the R.P. transformers and their associated vari- (Ct in Q. 2321A) of the tube itself. When the able condensers) is deliberately raised a to such feed -back current gets into the oscillatory circuit ATWATER value that the circuits cannot oscillate by their formed by the transformer secondary and tuning KENT CIRCUIT own resonance; in spite of the fact that they condenser, it merely dissipates itself in the high (2322) Mr. H. Webb, Yonkers, N. Y. writes: tend to do so because of the "shocking" effect of resistance of that circuit. e\ simple resistor (R in (Continued on page 693)
AERIAL C4 L.S. o .00025 ME RI RFT R2 RFT AFT AFT o o 0o 0o o o C3 / o o 2T04 MEG. I- C5 o `---.001 MF. GND R3 R4 RED., oA+ BLACK o A- YELLOW C6 SW oB+DET. WHITE-t, 0B+ R.F BROWN oB+A.F. BLUE; Q-2322 oC
IT re Atwater Kent "Model 20," one of the most popular receivers ever built, NEWS (page 44) will be found an article on adapting this receiver to modern in its day, used the circuit shown above. In the July, 1928, issue of RADIO conditions with an added power stage for a large core speaker.
www.americanradiohistory.com Radio 1Vcros for Jauary, 1929
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same Aaa`g Please say you saw it in RADIO NEWS
www.americanradiohistory.com 664 Radio News for January, 1929
,,,,,,1,,,,,,,,,,1,,,,,1,1,,,,,,,,,,,,1,1,,,,,,,,,,,,,,,,,,,,111,,,,,,,,,,,,,,,1,,,,,,,, What's New in Radio ,,,,,,,,,,,,,,,,,,,,,,,,,1,,. (Continued front large 629) Broadcastatics , ,.,,,,,,,,,,,,,1,..,..,,,,,,,,,,,, ."1, I ,,,,, ." ,,,,,,,, word "Volume" is neatly etched over a ma- OF HARD -BOILED resistance; and THE hogany knob controlling the THE BUTCHER: the word "Radio" over the midget plug "What can I do for Actual Movie Filmy mounted under the control. Series wiring we supply you you this morning, showing electrical is used between receiver and volume con- machinery in oper- sir ?" ation and animated trol, requiring only two posts for connec- diagrams, make . ELDERLY CUSTO- electricity easy to tions. MER: understand. "My wife told me to stop in and get some meat for dinner; and I .Learn thought for a change we would try a pound of that radio `ham' I have read about so often. " -Alfred M. ELECTRICITY Spacer. by Actual Movies NO OLD STOCK MRS. FAST (who is doing a EAL moving pictures, in your own bit of shop - home, make the facts about elec- ing for hubby on the side) ; "I want to buy tricity easy to grasp and fascinating as a radio battery, too." seeing a movie in your favorite theatre! CLERK: "Storage ?" You learn quickly, prepare for a big Mas: FAST (indignantly): "No, of course pay job in this ever -growing field. non I want a ggod fresh one!" Everything Supplied, -Melvin ATordstrand. No Extra Cost HE KNEW HIS RADIO Standard DeVry Movie Projector, so simple anyone can operate it imme- o TEACHER OF AL- diately without experience. Used with DEBRA (to inatten- y4 % / f regular light connection, farm lighting tive student); .y equipment, or auto battery. Thousands "Johnny Jones! /7 of feet of film-all supplied to every What is the result ]? cost. student at no extra if I add minus A to \ Only School Using plus A ?" Real Movies Jon xxy (whose dad is a set build- get movie Nowhere else can you real er) : "I know, Miss instruction in your home. Electricity, automotive electricity, and drafting all Cyphers ! A short circuit I-Michael Chec- included in this wonderful course. kolo. Prepares you for all kinds of electrical board, work in aviation, radio, switch- HOW power plant operation, contracting, etc. TIMES HAVE CHANGED IN 1924: "Gee, that's a fine radio you've A Better Job at got: sounds like a phonograph." This attractive wall fixture provides a con- Bigger Pay nector for any room in which a loud speaker Ix 1928: "Say, that phonograph's the We pledge to give you the training is to be operated by a remote.control receiver. cat's, all right; sounds just like the radio." and employment service which helps -Leo Hostensky. you get a better job and more money Manufacturer: Carter Radio Co., Chi- or you need not pay a cent. The cago, Ill. moment you enroll we begin helping you make your training count in more dollars. Employment service gets you A Line- Voltage Safeguard 40 Non -Technical in touch with employers who want ANEW device, the use of which owners Film -Way trained men. of receivers using A.C. tubes will find Radio Articles Drafting Set Given valuable as a protective measure, is now be- convenient form. The Complete professional outfit, includ- ing marketed i a every month for the beginner, the layman object is a highly nickeled plug -in instru- and those who like radio from the non- ing fine set of instruments, drawing technical side. board, rules, scales, etc., everything ment with a self-contained and variable re- work included in voltage, needed for drafting sistor intended to reduce the line SCIENCE AND INVENTION, which can this course given at no extra cost. should it be too high. This instrument be bought at any newsstand, contains the designed as to appearance and largest and most interesting section of THREE is cleverly radio articles of any non -radio magazine FREE Lessons operation, and has the advantage of being in existence. and our new book"Tbe inconspicuous, a factor generally desired by the average set owner, as well as convenient Plenty of "How to Make It" radio arti- Film WaytoBiggerPayrr cles and plenty of simplified hook -ups for Get in the big pay ranks. to adjust. the layman and experimenter. The radio Send the coupon for Manufacturer: The Wirt Company, Phila- section of SCIENCE AND INVENTION information about this delphia, Pa. is so good that many RADIO NEWS to readers buy it solely for this feature. You Use This new, easier way DeVry Projector learn electricity. Radio Articles Appearing in SCHOOL of She NATIONAL January Science and VISUAL ?I EDUCATION Invention Magazine _" Aire Film Way So Bigger Pay -MI= llama BY RADIO 537 S. Dearborn St., Chicago, Ill., Dept. 1-D I SURVEYING 1 Without obligation send three free lessons and APARTMEIÑT HOUSE AERIAL your new book, 'The Film Way to Bigger Pay" I -By S. R. Winters A.C. SET HINTS -By Paul L. Welker Name NEW RADIO DEVICES ISt. or R.F.D RADIO ORACLE ICity LATEST PATENTS A very handy voltage control which plugs ' State, County into the light -socket operating the set. Please say you saw it in RADIO NEWS
www.americanradiohistory.com 665 Radio ATM'S for January, 1929 FACTORY TO YOU -SAVE 50%-COMPARE WITN COSTLIEST OUTFITS BEFORE YOU BUY, set or complete powerful new outfit DAY AC Electric or Battery g RE= 3 Year Guarantee
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www.americanradiohistory.com 666 Radio News for January, 1929 Until You Have Heard the Home -Made Dynamic Speakers tric cell has become an object of more than usual interest on the part of designers of In Favor Abroad vacuum tubes. The huge ten -and twelve - 1929 inch cells formerly found necessary for ef- 'ALT OW can I make a loud speaker of the ficient television transmission are giving i dynamic type ?" This question is be- way to comparatively tiny ones -only two A. C. Victoreen ing asked with increasing frequency by and three inches in diameter, but possessing readers of RADIO NEWS, whose letters plainly equal or, in some cases, superior light - You Have Not Heard indicate that there is considerable interest sensitivity. The advent of these cells will in the subject. mean a considerable reduction in the size The Best The answer is that you can't unless you and expense of television machines, and an have a complete set of special iron castings advantageous increase in their range and for the framework. Once you obtain such flexibility. castings, the rest of the construction will In a new experimental television trans- present no difficulty if you possess a high mitter constructed by John Geloso, who is degree of patience and a fair amount of responsible for WRNY's successful tele- skill in the handling of ordinary hand tools. visor, four three -inch cells are used with a You will have to wind an endless lot of fine system of reflectors which makes them as wire on one of the castings for the field responsive as the big twelve-inch cells now magnet, and you will have to mount the in regular use at WRNY. The reflectors This marvelous new Super Circuit, cone and its attached moving coil rather are of polished metal, about eight inches in developed and perfected in the Vic - carefully; but there is nothing particularly diameter, and look exactly like automobile toreen Laboratory, is by long odds complicated about these operations. The headlights without the front lenses. A cell the most sensitive and selective ever problem is to get the castings. is mounted at the focus of each reflector, offered the set builder and radio In Great Britain several radio manufac- with its sensitive side ( "window ") facing "fan." It literally bristles with new features, any one of which would be turers have found it profitable to put com- the surface of the latter, and with its considered sensational in an ordi- plete sets of castings for dynamic speakers opaque side facing the person being tele- nary circuit. on the market and, according to the British vised. By all means have a new Victoreen, radio "'magazines, many constructors have As the televisor is of the "indirect -spot- if you want to enjoy real radio re- successfully assembled very satisfactory re- lighting" type (see definition in a previous ception. Either build it yourself in producers. However, in the United States paragraph) the light reflected back from a few pleasant hours, or have it the effective demand for such castings is the subject hits the polished surface of the " built for you. It will bring you dis- not yet heavy enough to encourage manu- reflector, which in turn throws it into the tance, selectivity and tone quality facturers to go into production on them. If photoelectric cell. As the light -gathering such as you have never known be- any manufacturer should decide to make surface of the reflector is considerable, the fore. them available for the benefit of individual small cell produces an output equal to that Part of the wonderful improvement radio fans, RADIO NEWS will be glad to in- of the larger cells. Several views of this is due to changes in the circuit it- form its readers thereof. Meanwhile, the transmitter are shown on pages 630 and 631. self, and part to the redesigned R.F. Transformers. These Transformers, only answer to the question from an Ameri- The apparatus was exhibited at the Elec- tuned and matched to a precision of can fan, "How can I make a dynamic trical Show held in New York last October, 1/3 of one per cent, are years ahead speaker ?" is "You can't." find proved to be one of the main attrac- of their time. They perform equally tions of the show. well in either the A.C. or D.C. cir- cuits. FOREIGN TELEVISION ACTIVITIES Blue Prints FREE In Great Britain the company exploiting Together with full constructional Latest Developments In the inventions of John L. Baird, the noted data. We've made it easy for any- Scotch television expert, has displayed a one to assemble a Victoreen. State Television number of complete television receivers in- whether you are interested in the (Continued from page 631) tended for the commercial market; but just A.C. or D.C. circuit. what any purchaser can do with them, in terwoven and overlapping spirals are pro- the absence of actual television broadcast- To get the utmost in results duced each second, producing in the recep- from any receiver, use the new ing, is highly problematical. The company tor using neon glow -lamps a luminous or has definitely promised a television service VICTOREEN glowing field, with sectional variations de- but, because of the peculiar status of broad- "B" Power Supply pending on the intensity of light impressed casting in Great Britain, we do not see how upon the corresponding photoelectric cells it can proceed with its plans until either at the transmitter by the reflected object. the British Broadcasting Corporation or the "A model developed in the laboratory is British Post Office changes its mind. approximately 18 inches in diameter, with a The British Broadcasting Corporation, sphere of vision 10 inches in diameter. Care- universally known as the B. B. C., has a ful study has revealed the fact that, when monopoly on broadcasting in England, the revolving disc turns upon its axis at a speed of 1,000 r.p.m. and the fork hub car- rying same revolves at 3,600 r.p.m., the five cells individually and separately will pass Station through the sphere of vision and make 18 complete per revolution; a total of Here is the last word in "B" Supply and spirals Power Amplifiers. Uses either a U% 250 18,000 spirals per minute or 300 per sec- or 210 in the last stage. Two voltage regu- ond." NEW YORK' lator tubes accurately control the 90 and 297 METERS -1010 KILOCYCLES 180 volt taps, thus making possible accu- This system sounds very interesting, but and W2XAL, 30.91 METERS rate determination of proper "C" voltages. it also appears to be rather complicated a 0 90 volt variable; is owned and operated by the There is also to tap, As soon as also 450 volts for the power tube. from the mechanical standpoint. titis mpgakine BLUE PRINT IS FREE, together with further data on it are released or demon- publishers of list of parts and complete assembly in- Our Editors will talk to you structions. Write,for it today. strations given, RADIO NEws will report them in full detail. several tames every weele- The George W. Walker Company See jourourI(ewsp er Merchandisers of Victoreen Radio Parts INCREASING PHOTOELECTRIC-CELL details 2825 Chester Ave., Cleveland, Ohio EFFICIENCY TUNE IN ON With the newly- created interest in tele- WRMY vision, as well as in sound -reproducing films and other developments calling for the translation of light intensities into corres- ponding electrical intensities, the photoelec- Q u a l i t y Radio Parts Please say you situ, it in RADIO NEWS
www.americanradiohistory.com Radio News for January, 1929 667 AVOID STATIC" DISTORTION INTERFERENCE
Now Make Your Radio Clear As a Bell With Marvelous New Underground Aerial ! Did you know that radio waves go through the ground just as they do through a building? If you had your set down in a deep mine, you'd get the program just as you do at home! In fact-and here's the surprising discovery that is revolutionizing radio reception -you'd probably get much better results. Scientists say that when the receiving antenna is below the surface of the ground, the earth absorbs practically all the static and other inteference, and allows practically only the clarified tone to reach the set. Starting from that important fact, radio engineers worked out the SUB -AERIAL. Set owners everywhere are now en- joying real radio pleasure with this marvelous new invention. How SUB -AERIAL Works Anyone can install the SUB -AERIAL in a few minutes. Simply bury it about two feet below the surface of the ground and bring the lead -in wire to your set. SUB -AERIAL then takes the radio waves from the ground and brings them to you sweet toned and clear as a bell. Howls and shrieks due to static -laden air conditions are reduced and your real radio enjoyment begins. SUB -AERIAL never needs to be touched again.
PROOF 25 Year Guarantee Test after test has been made with SUB -AERIAL with amazing Any SUB -AERIAL installed that proves defective either results. Radio engineers. maga- zines and funs heartily endorse in workmanship or materials or which deteriorates within SUB- AF.11IAL. May 8th. 1928. 25 years will be replaced free of charge; also we will pay am very glad to state that testing many Aerials in my $1.00 for any such new replacement. Lafteraboratory I find your Sub -Aerial is the best for clarity of tulle and elimInat Ion of stat le. also for greater selectivity. Your'oSub-Aerial will t li a long -felt want among Radio Fans." TRY IT FREE ! A. B. Johnson. Radio Engineer. August 31st. 1928. Don't hesitate to send for SUB- AERIAL "I received my Underground You take no risk. When Aerial all O. K. It has any on Free Trial. aerial beat I have ever seen. I you get it, test it against your overhead have used every aerial on the market sine I have been a radio aerial and compare the two. If you are not fan. The first day I Installed it astonished at the difference SUB - I got distant stations that toy act -if had never touched before. It AERIAL does not bring in reception with wasn't good radio weather either. I got stations in the East that I marvelous tone value, clear as a bell -if it had never dreamed of getting and doesn't give surprising volume and distance with absolute clearness and with- out lc -if you are not more than satisfied you heartily t recommendinterference.your tt instru- to any lover of goal radib don't pay us a cent. Send coupon for the reception."ment fascinating story of SUB- AERIAL. Do it A. N. whitatm. Mail This Bog 565. El Reno. Okla: NOW! Coupon Today AERIAL SYSTEMS UNDERGROUND UNDERGROUND AERIAL SYSTEMS, Dept. 827 -A.S. St. Clair Bldg., Dept. 827 -A.S. Cor. St. Clair & Erie Sts., Chicago, Ill. St. Clair Bldg., cor. St. Clair & Erie Sts., Chicago, Ill. Send me complete information on Sub- Aerial and Frei, Get Reception You've Always Wanted Trial Offer. No obligation. Name Address City cic1th.SlIBAERIA State
www.americanradiohistory.com 668 Radio News for January, 1929
granted by the government. It has refused to co- operate with the Baird company be- cause its engineers do not believe that Baird's system has reached the stage where 6,1(6 LL,-O it can be considered a public utility. The Radio Consoles Baird people have proposed to erect broad- cast stations of their own, but the Post- Designed for Atwater Kent, Crosley and all master General, who is charged with the ad- standard A.C. Receivers. ministration of England's radio laws, has refused them the necessary license, on the same technical grounds presented by the 13. B. C. As the Baird company displayed its machines at the recent annual London radio show, and has already issued printed catalogs, the situation is somewhat muddled. The Baird company has a New York of- fice, but little information about the com- pany's American plants can be obtained from it. A secret laboratory, in which de- velopment work on the Baird system is be- ing carried on, is supposed to exist some- where in this city, but nothing definite is known about it. RADIO NEWS in the past has devoted a great deal of space to Baird's television achievements, and will continue to describe them if he releases the technical lata on them. In Germany, at the recent Berlin radio fair, the Karolus and Mihaly systems were exhibited and aroused public interest fully equal to that which huge crowds exhibited at the American and British expositions of television. Some illustrations of apparatus RADIO STYLE R -4S / TUBES used by these methods appear on pages 636 Size 51 1n. z 26 in. z 16% in. and 637 of this issue. Highest quality cabinet work, all panels five - ply walnut, doors matched butt walnut.- Re- ceiver compartment is sliding drawer; accom- carry you safely modates set and speaker. Walnut finish, band rubbed, At your dealers or write for complete to all "Front - Tubes in a Class with the catalog of many styles. Estella Products Corp., 4832 W. 16th St. Pullman Cars Cicero, Ill. (Suburb of Chicago) page" events INVENTIVE progress is perpetually put - sting a strain on the coiners of new words, With a new, wide - as witness the increasing complexity of X -L LINK tubes. The new five-element tube, described awake Cunningham in the October issue of RADIO NEws, is now THE ONLY UNIT THAT COMPLETELY quite the latest fad among British experi- LINKS THE RADIO Tube in every SET TO THE LIGHT Radio menters. The "pentode," with an ampli- SOCKET fication of 60 to 80, must follow the de- socket of your set you List Supplies the following tector, giving a single stage of audio with toany receiver: Antenna a powerful output. Its additional element, Price and Ground from are "among those shielded light wires. another grid next the plate, is filament Voltage Regulation pro- at $5.75 tecting tubes and set. potential and prevents the return of elec- Double Socket provides present" whenever outlet for Dynamic trons from that element. (This tube is Speaker. Complete Fus- ing eliminates fire haz- and wherever things not yet available in the United States!) ard. Control Switch for in prover unit set or Dy- We now have as a possibility a radio namic Speaker installed happen. With these set the following: in a moment. No wir- ing or changes in set. sentinels on Monodes (one-element) Dial lights Unqualifiedly guaran- faithful Diodes (two -element) _Rectifiers teed.
duty, you are reli- Triode (three -element) ...._._...._.....Detector IF YOUR DEALER OR JOBBER CANNOT SUPPLY Tetrode (four- element) YOU ORDER DIRECT. ably radio -informed. Screen -Grid R.F. Amplifiers Pentode (five -element) A.F. Amplifier If the same inventive genius continues to XL Rad io Laboratories Look for the mono- exert itself, we may have (6) hexodes, (7) Dept. A. 1224 Belmont Aye., Chicago, 111. heptodes, (8) octodes, and so on to the v- n-Flst "ode." gram on the to But let us consider the further possi- bilities; the filament and plate are the Before"A" Buying "cathode" and "anode," as many know; and C Any Eliminators of each tube and in- Write me about the discount card which en- our British contemporaries suggest that the ables ou to purchase the new and improved first grid is appropriately the "mesode" Knapp "A" Power Kit sist on them by name. or middle element. This smacks of the ge- at a liberal discount. ologist's vocabulary. How we to name The most complete "A" Power Kit ever are offered -Address for details of plan the multiple strata of grids which the tube - David W. Knapp, Pres. E. T. Cunningham,(Inc. of the future will have? Cenode, Eode, '.;a Knapp Electric, Inc. Pliode, Pleistode, Holode, and perhaps Ju- Room 417, 350 Madison Ave., N. Y. C. NEW YORK - CHICAGO rassode and Silurode? SAN FRANCISCO It is none too soon for the radio engin- eer to start dusting off his Greek dictionary, Insure your copy reaching you each month. Sub- which has lain on the shelf since the last scribe to RADIO REWS -12.50 a year. Experi- "'dyne" was christened. menter Publishing Co., 230 Fifth Ave., R. Y. C. Please say you saw if in RADIO NEWS - www.americanradiohistory.com
669 Radio News for January, 1929 WHOLESALE PRICES. ti forDealerts, ommunik SeEBuilders, General Repairmen NEW ISSUE! and Agents! JUST OFF THE PRESS! Our new, HUGE 260 PAGE WHOLESALE CATALOG No 19 enjoys the enviable dis- tinction of being universally accepted by the RADIO TRADE in the same manner that a school treasures the Dictionary and En- cyclopedia Brittannica -or the home the Bible and Almanac!!
The preparation and distribution of this MAMMOTH Catalog COSTS A TRE- MENDOUS SUM -the huge volume of business derived from it warrants this cost I as well as the genuine pleasure it gives us to know that those "in the know" regard our G catalog AS THE OFFICIAL ORGAN OF THE 1929 RADIO SEASON!!! P This FREE CATALOG is literally a most valuable ENCYCLOPEDIA -YOU cannot R well afford to be without one -and, you do not have to. Your request for one is all I that is needed! A day or two later, it is in your possession. Surely, a TEST OF C OUR PROMPTNESS PLEDGE! And we are right on the job, ready E to supply television apparatus, too! We list more such parts than C appear in any other Radio Catalog. U Those having No. 18 Catalog should immediately send S for No. 19. ALL THIS PRICES HAVE BEEN REDUCED 260 PAGE TREMEN- 975 DOUSLY! OOKUPS RADIO 1500 We can supply any CATALOGUE parts and kits de- I LLU STRATIONS scribed in this issue. Send for prices FIEF at once!
IJtLYÌs2Torn *adios Oldest Mail Order Souse! an organization must be efficiently run in In these many years we have been in the Radio Mail Order Business, we have learned from EXPERIENCE how such order OF CUSTOMERS. In this, our DETERMINED GOAL, RADIO SPECIALTY COMPANY OFFERS to GAIN AND RETAIN THE GOOD WILL OUR A MONEY-BACK TO SHIP ALL ORDERS IN FROM 6 TO 24 HOURS- OFFERS YOU 100% QUALITY MERCHANDISE ON STRICT BASIS IF NOT THOROUGHLY SATISFIED -AND OFFERS YOU ALL MERCHANDISE AT ABSOLUTE ROCK BOTTOM NET PRICES( Our employees -our executives, are all pledged to handle your every order and inquiry in an intelligent manner. Our 24 -HOUR SHIPMENT SCHEDULE MUST BE UNRE- SERVEDLY MAINTAINED! And to this pledge, we owe our daily increasing patronage. It will pay YOU to r be numbered among our many thousands of customers! A trial is all we ask! OUR CATALOGUE CONTAINS THE LARGEST ASSORTMENT OF RADIO MERCHANDISE IN THE COUNTRY. Only the post successful manufacturers' products are listed -such lines as PILOT- SILVER- MARSHALL-CARTER- AERO-YAXLE.Y- THORDARSON- MUTER, etc., etc. THE LATEST IM- RASCO has it ' OlsE- HA) IMARLUND- AMETRAN-CUNNINGHAMI-DONGAN- PROVEMF.NTS IN RADIO ARE LISTED AND THOROUGHLY DESCRIBED IN THIS GREAT CATALOG: A.C. ALL ELECTRIC Sets with self-contained ABC power supply -Public Address Ampli- not list in our cata- fier systems -A.C. Set Converters-A and B eliminators- Dynamic Speakers and Units -Magnetic And, if we do Speaker Chasses - 250 Tube Amplifiers - Airplane Cloth Speakers -Push-Pull log your Radio requirements, WE Power Amplifiers -Electric Phonograph Turn -Tables -Combination Radio and Electric Phonograph Consoles-Speaker tables -Short wave Sets and Adapten- WILL OBTAIN SUCH PARTS, Shield Grid Tube Kits- Television Parts. LOGICALLY. HOW CAN YOU BILLING YOU AT THE USUAL AFFORD TO BE WITHOUT OUR CATALOG-SEND FOR ONE NOWT TRADE DISCOUNTS!
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www.americanradiohistory.com 670 Radio News for January, 1929 The Radio Beginner -The "Bloopless" Two (Continued from page 646) Make Your Set a Modern 7hourandr It has been found that the best all -around A. C. Power Receiver aerial for broadcast reception is a single CE wire, 75 to 100 feet in length, and elevated call Co the 50 or 60 feet above the ground. Either solid or stranded enamelled wire may be clearest toned used-whether the gauge is 12 or 14 makes hardly any difference-with a strong recom- longest life - mendation of the -solid wire if the aerial is to be erected in a congested area, such as a large city, where excessive acid - fumes, tube on the smoke and soot will eventually coat the wire with a high- resistance layer which is market. detrimental to efficient reception. Wherever New possible, the aerial should be erected clear of any surrounding trees, buildings, etc., and the same advice applies to the lead -in; AMP L I PACK which should come down A Complete A. C. Power Supply -"A" and "B" and from the aerial "C" -Makes any D. C. Set into an Ultra-Modern A. C. at a 45- degree angle rather than make a Receiver. Uses two 210 type tubes in Push -pull; or straight drop parallel one of the new 250 type tubes. Power AmphScation to the side of the gives perfect reproduction over the entire musical scale building. range. It hardly pays to economize on insulators QUICKLY ASSEMBLED when these You can assemble an AmplipaCk easily handy little articles mean so In one evening. We supply complete FREE much toward an efficient installation. layout diagrams. Simple to install. Booklet They Attached to setlin three minutes. Con- should be used wherever there is possibility sumes no more current than an ordinary write for our 50 -watt light. Cool. Quiet, dependable. new Free Book- of any part of the antenna coming in con- let-the latest YOUR word on Power tact with any section of the structure. Us- ASK DEALER Ampliflcatlo n ing Leading dealers can give you full details and A. C. Con - a piece of wood to keep the lead -in and our simple assembly diagrams. version. from touching Don't be satisfied with out -of -date recep- the side of the building is tion -build an AmpllpaCk tonight! nothing more than providing an excellent short- TRANSFORMER CORP. OF AMERICA circuit for the aerial should it rain 1428 -1432 Orleans Street, Chicago Ill. or snow. A piece of twine or Manufacturers of the T. C. A. Line of Power Transformers. rope, often Audio TranstormersiChokes, Power Packs and Power Amplther used in place of a piece of wood, is just Packs. as bad. Installing the ground should be in the nature of a ceremony. There is no doubt that the best ground comprises a number of large copper plates buried six to ten feet-underground in moist soil. However, to the city dweller this may sound like scienti- Wholesale f'iction; in his case it is best to test every available pipe in the house to Prices see which one Tremendous gives the best results. For example, the stock and sales vol- average ume, with rapid turn -over to the city home has water and steam - thousands radiator pipes. of radio dealers we Of the two, the water pipe serve enables us to make you is usually better; but this does not mean worthwhile savings at lowest that the other should not be tried. It may wholesale prices. Write for lat- be found that a certain combination wherein est, new illustrated Catalog "B -3" two are joined together is better than using only one. When connecting the ground lead to the pipe, try soldering it; though some AlliedPRadio difficulty may be CORP RATION experienced with iron pip- 711 W. LAKE STREET, CHICAGO ing. When such is the case, an ordinary "ground damp" will give good service if the section of pipe it is to be wrapped about ...avid it ought to is thoroughly cleaned and scraped until the bare metal shines. A ground clamp secured be- here's why about a water pipe should be examined and cleaned at least every three months. (Warn- lik finest materials skillfully ing: do not use the gas pipe as a groun¡l.) `JP 'ot ra T"employed by able craftsmen Nros ,p4 ail1R and the foremost laboratory ex- MURDER! HELP! POLICE! SLUGGE: ° hrraa.No t9aud 'r o` ! "The perts give CeCo marked advan- MrCALLS HEN FAMILY yV SURE! E RADIO CONNECTORS tages'over other tubes. Mothproof Hosiery varld Favors. Connectors Fo,Readrtiade Ant Home Made Sets Co. is sponsoring the FRED R. COATS MFR. CO., SPRINGFIELD, ILL They have not only a purer, broadcast of the big clearer, more pleasing tone, but a fight tonight." MoreProfits To Set Builders longer, more serviceable life. SLAMME : "Ah, One good radio idea may be worth Try them! Sold everywhere. putting the socks on millions. Barawik has thousands of ideas for radio set builders to make more money. the air, eh?"-Wm. Barawik'a Big Radio Book will help you CeCo Mfg Co., Inc. Providence, R. I. while elections are on and big national G. Mortimer. events stir the world. Seed for your copy today - NOW. B A R A W I K C O e CHICAGO. U. S. A. A TOP- NOTCHER Mail This Coupon Now! For Free Copy ¡ THE MUSICAL SAW: "That announcer Name thinks quite a bit of himself, doesn't he ?" THE UKULELE: "Rather! He won't an- Address wCTube' nounce for a station unless they have an exclusive wave! " -Wm. G. Mortimer. Please say you saw it in RADIO NEWS
www.americanradiohistory.com Radio A'cu.'s for January, 1929 671 Hints on the "Junk -Box" (Continue( fron page 61.6) between regeneration and oscillation. When the regeneration condenser C2 is turned up slowly, the operator will begin to hear a soft, "hushing" sound. At a critical point this "hush" will flare out into a quick "plop." Now, during those few degrees of con- denser movement when the set is making the "hushing" sound, it is said to be re- generating, and in this condition it is ex- tremely sensitive to voice and music signals. When the "hush" breaks into a "plop," the set is said to have started oscillating; that is, it is now generating radio -frequency os- cillations or current of its own. These cur- rents by mixing, or "heterodyning," with the radio-frequency currents picked up by the aerial and already present in the circuit, produce the whistles and squeals so char- acteristic of short -wave operation. The dif- ference between regeneration and oscilla- tion is one merely of circuit adjustment; but though the two conditions are very closely related, they serve two distinct purposes. For the reception of voice and music signals, as transmitted by broadcast sta- tions, the set should be regenerating as strongly as possible without actually break- THE SHORT-CUT ing out into oscillation. It will not squeal when it is regenerating; if it does squeal, you may be sure it is then oscillating. Pick- ing up distant short -wave broadcast sta- to BIG MONEY in tions is entirely a matter of the operator's skill in adjusting the regeneration control, "WORTH over $5,000 to me! " "Never so in this case the little variable condenser V V thrilled in my life!" "Never dreamed C2. As remarked previously, the set may Radio was so easy to master!" RADIO be thrown into oscillation and the incoming wonder -book signal "zero- bent;" but this requires a little So scores of men write of this Sponsored by which tells how to achieve brilliant success Training RCA... practice. General Electric... Westinghouse To locate a broadcast in Radio. Send for your copy -it's Free! station, the easiest Our graduates enjoy greater success because thing to do is to throw the set into oscil- Glorious New Opportunities -minute in lation they're posted right up -to- the and then to hunt for squeals. As soon everything in Radio.Radio's greatest achieve- as one is heard, the setting of the tuning Radio needs you! Over 30,000,000 sets need servicing. Over 2,000 ships carry radio appa- ments originate in the gigantic laboratories condenser should be carefully noted, and of RCA, General Electric and Westinghouse. the regeneration condenser slowly turned ratus. There are 50,000 radio dealers, 4,000 radio manufacturers, scores of broadcasting These three Radio organizations stand back down. As the set goes out of oscillation of every lesson in the course. and back into regeneration, the squeal will stations. And now Television, trans-Atlan- disappear. With a slight readjustment of tic Radio Telephony, and Photoradiograms Money Back if Not Satisfied the tuning condenser, made as the regenera- open up brilliant new possibilities! The Free course prepares you for success in all tion control is juggled, the voice and music book tells all about them. It tells also how The should become understandable. the you can make your spare time prepare you phases of Radio -manufacturing, servicing, If sig- selling, ship and shore broadcasting, and nals are very weak, zero- beating is usually for success through a revolutionary new the best thing to attempt. method of training. many others. IncludesTelevisiona'hotoradio- grams, and radio equipment. A signed agree- TUBES ARE TEMPERAMENTAL Learn at Home with ment assures you of complete satisfaction This Big Laboratory Outfit upon completion of the course -or it won't Smooth regenerative action depends to cost you a single penny! a great extent on the characteristics of the You get the "how" as well as the "why" of particular detector tube used, the value of Radio with this fine training. Only an hour Send for this Free book now. Why struggle the grid leak, and the amount of "B" voltage a day -in spare time -is all you need to de- along on less than $45 aweek? Why wait years applied to the plate of the tube. A number vote! As part of your course, you receive for success that can be yours in only 9months? of tubes that seem to be identical in opera- absolutely free of extra charge-a magnificent Read this Free book. It gives you the real tion in regular broadcast receivers will be outlay of apparatus. With this outfit you dope about Radio and tells you all about the found to differ markedly when they are learn to build fine sets and solve every prob- famous course that has enabled us to plaoe tried in a short -wave set. Some tend to lem in repair work. That is why our gradu- thousands of our students in fine positions, break into oscillation quite violently; others ates have the confidence and ability to com- usually from 3 to 10 days after graduation! refuse to oscillate at all. Before rejecting mand big pay. That's why they're in big Mail coupon now. Radiolnstitute ofAmerica, any one tube as unsuitable for use as a demand everywhere! Dept. WS-1, 326 Broadway, New York. detector, the experimenter should try re- ducing. or increasing the voltage, "B" and RADIO INSTITUTE OF AMERICA, also grid leaks of different values. The Dept. WS-1, 326 Broadway, New York original specifications for the set call for Gentlemen : Please send me your big a three-niegohm grid leak, but in many FREE 50-page book which tells about the cases a five- megohm will work better. great opportunities in Radio and about Another trick that will often be effective your famous laboratory-method of guar. anteed radio instruction at home. to aid the regenerative action of the set is that of connecting a .001 -mf. fixed con- Name denser across the primary of the audio Address transformer. The self-capacity of the pri- mary windings of most transformers is Please say you saw it in RADIO NEWS www.americanradiohistory.com 672 Radio -V S for January, 1929 Dr.T.O'Conor Sloane will teach ,You. ow CH EM1STRY Right in your own Home Good Chemists Command High Salaries
Industrial firms of all kinds pay tempting salaries to get What Well -Known the right men. Salaries of $10,000 to $12,000 a year are not Say unusual for chemists of exceptional abilities. Chemistry Authorities offers those who are ambitious and willing to apply them- About Our Course selves conscientiously the greatest opportunities of any vo- From Iludson Maxim: cation. Why be satisfied with small pay and hard, thankless Ur. Sloane has done a much- needed your salary will work In a much better way than any- work-learn the profession of Chemistry and thing of the kind has, heretofore, been depend only upon your own efforts and your own abilities. done. "Dr. Sloane has a remarkable faculty The work of the chemist is extremely interesting. If you of presenting Science for self-instruction and fasci- of the student in such a clear and un- are fond- of experimenting, if you like exciting derstandable way as to be most readily nating work, take up Chemistry. To the man who is dis- grasped and assimilated. satisfied with his present job to the young man just deciding 1, therefore. unreservedly recommend on his life work, Chemistry bolds alluring charms and count- and place my highest indorsement on his less opportunities. If you want to earn more money, the work." way is open through our course in Chemistry. From Dr. W. W. de Eerier: "I can not recommend your counts too highly and I congratulate both you and Dr. Sloane on same." THE TIME TO From John A. Tennant: NOW IS "This is something which has long been needed. Your long experience in the teaching of chemistry . . . assurance T. O'CONOR SLOANE STUDY CHEMISTRY that the course will be practical as well / A.B., . LL.D., Ph.D. as plain to the untrained students." A.M. Toted Instructor, Lecturer and Never before has the world seen such splendid oppor- What the Students Say: Author. Formerly Treasurer Ameri- "Your course has been worth can Chemical Society and a prac- tunities for chemists as exist today. The war has awakened $50,000 and chemi- to my concern." tical chemist with many well known the United States to the need of trained chemists "This is just like reading some fas- achievements to his credit. Not cal engineers. Everywhere the demand has sprung up. In cinating fiction story." only has Dr. Sloane taught chemis- electrical shops, industrial just try in the classroom. but he was factories, mills, laboratories, "I have been made assistant chem- for many years engaged in com- plants of all kinds, chemistry plays a vital art in the con- ist of my concern." mercial chemical work. tinuation and expansion of the business. In every branch "You may be pleased to learn that I has arisen. No have re- entered the laboratory of my for- of human endeavor the need for chemists mer employers as their chief chemist. The profession offers such alluring opportunities, and the next work under my care involves several hun- ten years are going to show the greatest development in this science that this country has ever seen. dred thousand dollars a year." Those who have the foresight and ambition to learn chemistry now will have the added advantages I am going to keep right at the study, field is growing and expanding. for it has helped me greatly. It is really and greater opportunities afforded while the chemical the knowledge I have gained from it that made it possible to hold the job I have at present." "Let me state that I have obtained a new and better position; this is with the Heller and Mere Aniline Dye Co. in their Home main laboratory. Thanks to course You Can Learn At your I am well prepared and able to bold Ability to Understand Plain English the Only Requirement sane." "Let me state that I have obtained a Dr. Sloane will teach you Chemistry in a practical and intensely interesting way. Our home new and better position; this is with the study course written by Dr. Sloane himself is practical, logical and remarkably simple. It is illus- Heller and Mere Aniline Dye Co. in their start that anyone, no matter main laboratory. Thanks to your course I trated by so many experiments that are performed right from the am well prepares] and able to hold same." how little education he may have, can "I now have a fine position as chemist thoroughly understand every lesson. Dr. at the Du Pont Dye Works. It was thrn Sloane teaches you in your own home your course alone that I have been so successful." Experimental Equipment Given with the same individual and painstaking I have written to different people care with which he has already taught about your course and they speak very to Every Student thousands in the classroom. He will, highly of sane.' in addition, give you any individual help If I don't learn it isn't your fault you may need in your studies. This per- for I find that your lessons contain a sonal training will be of inestimable whole lot." value to you in your future career. (Names and addresses on request.)
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Your name and address on the coupon will bring you j Please send me at once. , without any obligation on my return mail our interesting free book, "Oppor- We give to every student, without additional charge, this by pan. your free book, chemical equipment, including fifty pieces of laboratory ap- tunites for Chemists" and full particulars about the for Chemists." and full parpuni- - paratus and supplies and thirty -nine different chemicals and re- course and what it will do for you. You owe it tirulato about the Experimental Enulp- agents. The fitted heavy wooden box serves not only as a case to yourself to get this book. Send the coupon ment given to every student. Also please for the outfit but also as a laboratory accessory for performing , me about plan of payment. is mind. tell your countless experiments. Full particulars about this special right now while it fresh in your Or feature of our course are contained in our free book "Oppor- just write your name and address on a postal tunities for Chemists." and mail it to us. But whatever you do, ; act today! NAME Don't Wait - -Mail the Coupon NOW! / ADDRESS CHEMICAL INSTITUTE of NEW YORK, Inc. / 30TH STREET Home Extension Division 1 NEW YORK, N. Y. 16 -18R EAST CITY STATE s.. Ir R. N. 1.29 Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for January, 1929 673 usually sufficient to by -pass the radio -fre- quency component of the detector plate Çjq,4or6Voi current; but often the condenser will be s a great help. e AERIAL AND GROUND For short -wave reception the aerial need not be a very long one. In fact, a thirty - foot length of bell wire, thrown out of the window, will produce as good results as many longer and higher aerials, and will probably give less trouble with "dead spots" of r in the tuning condenser. As a matter knapp further fact, the "Junk -Box" outfit will work perfectly well without any aerial at all. When experimenting with the original coils APOWEP for the set, the designer, who knows how to read radio code, picked up amateur sta- tions all over the United States and Can- ada and from numerous foreign countries including Australia and New Zealand, all with the aerial post left absolutely uncon- nected. This reception was accomplished in New York City. 1 If the constructor does not wish to dis- ® I. Tlmprove turb the aerial he is using with his regular aq00 broadcast receiver, he can erect a fine aerial. for the "Junk -Box" set by merely tacking 21,sr4omen Per. some No. 24 magnet wire around the walls 3' i'I,ree filter srster,,. of his room, near the floor. Most directions 0 for the erection of indoor aerials call for 4. oFoeners° etb,y, ImPv ad the picture molding as the best place to 5, it is a great deal easier t s,vhcke Cods, hang this wire, but andÄdP to fasten the wire along the floor level, `Se4 We' '8" COn4o Operates on 105 to D 411 Fl+a6nas where it will work just as well. The regu- 120 volts, 50 to 60 9 fOrlte lar insulation on the wire, if it is double - cycles. against , Ba4erd°F,Pron. outage. cotton, is sufficient protection 9 is grounding. l0. r,Flvir Da The normal ground should be made in all Cast Ca °SeMetelc or °pd tse over. cases, to the most convenient water to astead, steam pipe. If such a pipe is removed sev- The only "A" Power f eral rooms from the location of the short- wave set, fasten the ground wire around Suitable for all Sets the nearest electric -light fixture. This makes a rather good ground and, contrary to ex- Irrespective of number of tubes - including introduce hum in the - pectations, does not receiver. SuperHets, Short Wave and Television receivers TILE CONDENSERS THE new Knapp "A" Power is designed for the most Hand- capacity effects seem to be giving short wave and some people trouble. 'With the rotors of exacting service -- super -hets, the two small variable condensers properly television receivers included. I knew that if it would connected to the filament end of the cir- satisfactorily with these receivers that there cuit, this should not be serious. Some types perform of condensers, however, are more trouble- could be no question as to its efficiency on ordinary some in this respect than others. The easi- broadcast signals. The three Elkon dry condensers, est thing to do is to mount them on a sheet of brass or copper, about five inches the improved choke coils and the special Elkon dry long and three inches high, and "ground" rectifier make the difference between ordinary and this to the filament circuit. The sheet will replace the two L-shaped mounting brack- Knapp performance. ets now supporting the condensers. No Change in Price The aerial series condenser (C3) shown in the "Junk -Box" blueprints is so simple Even with these wonderful and costly that many people actually do not understand improvements, there has been no ad- how it is made. This sounds paradoxical, vance in price -due to the tremendous but it is true nevertheless. The condenser consists merely of two flat pieces of brass, volume going thru my plant. Remem- facing each other. The plates are movable, ber that the Knapp is the fastest selling so that the distance between them, and hence "A" Power on the market. the capacity, may be readily changed. Any Devil W. 7p, arrangement at all by which two pieces of KNAPP ELECTRIC, Inc. Kna Pres. metal, each about half an inch square, may -Division of P. R. Mallory 6T Co., Inc.- be moved in relation to each other will 350 Madison Ave., New York City be t,ics., ,y6 satisfactory. The setting of this tiny con- denser is not critical, and will depend on See your dealer today the size of the particular aerial. J i Go to your dealer today. Most of the TAr'o ti Noe.. Y ° 'oQ ootye The "Junk -Box" receiver has proved to good ones carry the Knapp in stock. ttt° ss be one of the most popular radio sets RADIO Do not accept a substitute.- because e o`ev News has described during the ten years only in the Knapp will you get full Seoaoa°r' of its existence. More than nine thousand satisfaction as typified by the famous l+' . free blueprints showing its construction Knapp "A" Power. If your dealer bave been distributed to readers all over cannot supply you send the coupon. Please say yon saw it in RADIO NE1VS
www.americanradiohistory.com 674 Radio News for January, 1929
the world, and requests are still pouring in. A few blueprints are left; if you want to try your luck in the short -wave bands without spending more than about two dol- lars for a set, write in for a set of the Junk -Box prints. They are free, but you 2,000,000 must use the coupon on page 701 of this issue. Check off Blueprint No. 58, and write L your full name and address clearly. and how the Hotel MCAlpin SPEAKS R. , Human Radio Reflectors O PER4 ION (Continued from page 621) is spending it. ferent received strengths will therefore be obtained from different people. By bending from a the transmitting over when approaching An aerial, the effect is greatly decreased, since improvement program the body has 'then a different natural fre- that will make the McAlpin a C R/VlL7il quency, and is also not so well exposed to NEW Hotel .inside and out the waves from the transmitting aerial. NO "TUBES" - NO "B" BAT- In the May, 1928, issue of RADIO NEWS, Luxurious NEW carpets, dra- TERIES - NO COSTLY the reader will recall there appeared an peries and furniture throughout article which explained the temperature rise "ELIMINATORS" experienced by the human body when near -bright, cheerful, interior dec- WITH THE a powerful ultra -high- frequency oscillator. oration - spacious, IMMACULATE This is due to the currents which are caused rooms, all with modern tiled SKINDERVIKEN and to circulate on the surface of the skin, - TRANSMITTER UNIT which cause heating if strong enough. Med- baths -high -speed, electric, self Simple microphone unit provides a most effec- ical men have talked of producing artificial leveling elevators - and a NEW tive and inexpensive way to satisfactory speaker operation. Easy to build and operate circuit. fevers in this way, but the apparatus is type of courteous, efficient hotel Everybody can do this now with usually quite expensive. However, if the a Skinderviilren Transmitter Unit. service that enthuses the most The unit is fastened to the dia- frequency of the transmitting set is ad- phragm of the speaker unit. It will justed to the natural frequency of the hu- critical guests. set as a "microphonic relay." Every time an incoming signal actuates man body, a Maximum effect will be pro- the diaphragm, the electrical resist- smaller powers can be used for We invite you to visit the ance of the microphone unit will be duced and varied correspondingly and the cur- a given result, thus simplifying the arrange- McAlpin and inspect the NEW rent from the battery, in series ment and reducing the cost. with it and the loud speaker, will fluctuate accordingly. rooms - several of which are Thus the problem of securing sufficient power It is a simple matter, too, to arrange a to actuate the loud speaker is simply and adequately should already completed. solved. burglar alarm with two wires. This The results from this very novel and simple unit be so arranged that the relay will remain will astound you. Moreover, the re- All improvements are being The expense of this hook -up is trifling compared closed, if once thrown. to the elaborate tube circuits that give no greater lay can be adjusted so that only a definite effected without the slightest in- actuation of the speaker. frequencies will cause Besides this there are many other valuable uses in range of natural body- terruption of service. Radio Circuits for this marvelous little unit. Every operation. The expense is small, and the builder of Radio sets should have a few on hand. wires can be arranged inside the building; LISTENING THROUGH WALLS the presence of a body outside will operate FRANK A. DUGGAN This Unit makes a highly sensitive detectaphone, President and Managing Director the real thing -you listen through walls with ease. the alarm. Plenty of fun and real detective work too. Big -game hunters may desire, in the fu- CONDUCTING SOUND THROUGH ture, to use such a system. It would require HOTEL WATER n really clever animal to detect, at a dis- Make yourself a miniature submarine signaling of a small amount of apparatus like those used during the war. Simple tance, the presence circuit with this microphone unit gives splendid results. electrical equipment. Such a system might 12-PAGE INSTRUCTION BOOKLET be used to operate any other device by M`ALPIN containing suggestions and diagrams for innumerable using suitable relays. It is interesting to uses. furnished with each unit. think of the many other possibilities of this ONE BLOCK from PENNSYLVANIA STATION discovered effect. P. G. MICROPHONE TRANSFORMER newly A Modulation Trans- B'WAY at 34th ST. former specially de- signed for use with the Skindervikea Trans- mitter Unit. Has many What is a "Dynamic" Speaker? other uses. Primary resistance, assist the public in its purchases of ohm;see- 7 loud speakers, as well as to guide radio ondary. 55 TO FREE BOOK ohms. manufacturers, distributors and dealers in Sew Hook -ups. This hook their advertising, the Radio Manufacturers shows how to make Short -ware SALE AT LEADING DEALERS following defi- Receivers, and Short - Wave FOR Association has adopted the Adapters. Or Order Direct, Using Coupon Below nition of the "dynamic" speaker: How to use the new screen- arid tube in D.C. and A.C. "A dynamic speaker is one in which a dieu`` s. SEND NO MONEY How to build Power Ampli- When the postman delivers your order you pay lam for portion of the conductor carrying the al- aers, and ABC Eliminators. Up- whatever you have ordered, plus a few cents postage. is to- the -minute information on Write ternating signal current a part of the all new radio developments. f storing system, the force producing the Set Builders, Pans, Dealers, for 14 PRESS GUILD. INC. R.N.-1-29 send for it today! 16-I8-R--East 30th St., New York, N. Y. motion being due to the location of this KARAS ELECTRIC COMPANY 4038A1 Please mall me at once as many of the following Items conductor in a magnetic field." 40381 N. Rockwell St., Chicago, Illinois as I have Indicated. Please send nie your Free Book: ..Skindervhken Transmitter Units at 95e. for 1; 51.75 This definition was adopted by the R.M.A. for 2; S2.50 for 3; S3.20 for 4. Name P. G. Microphone Transformers at 52. at a meeting of its board of directors held When delivered I will pay the postman the cost of the in on 11th, 1928, upon its Address Items specified plus postage. Chicago October presentation to the board by Mr. H. B. City State Name Richmond, director of the R.M.A.'s en- Quality Apparatus Our latest bulletin No. 929 describing our com- gineering division. It was developed by plete line of quality apparatus is yours for the Address the committee on aural devices, of which asking. Write for it today. Mr. G. Andres is chairman. GENERAL RADIO CO. City State Paul 30 State St., Cambridge, Maas, Please say you sate it in RADIO N E TV S
www.americanradiohistory.com Radio News for January, 1929 675 Radio Wrinkles ,(Continued from page 653) a telegraph key and a triple -pole single - throw switch. After all connections arc made as shown in Fig. 7 (page 653) open the three -pole switch, don the phones, turn on the filament current, hold down the tele- graph key and turn the tickler control until the note is heard in the phones which is most pleasing to the code student. The' builder should be warned that this arrangement, with aerial and ground at- tached to the receiver, would be nothing less than a low -power transmitter, and as EDITION such come under the terms of the Federal law governing radio communication, which prohibits the sending of radio messages unless one holds both an operator's and a station license. So, even though you have an amateur's license, if you make use of T ElE VIdION this arrangement with a broadcast receiver and fail to open the three -pole switch, you 9 Magazine hr Experimenting Jn arc probably transmitting on a wave, any- where from 300 to 600 meters, which is "TELEVISION" is a magazine pledged to further the art illegal for an amateur. -Contributed by of the infant industry for which it is named, and to supply Warren Tuthill, Orient, Y. Y. the "fans" with the latest information and develop- ments in this fast -growing field. Television, as a science, occupies the same position today as radio Our readers are invited to contrib- did ten years ago. Like the radio fans of years ute ideas. A year's subscription to RADIO NEWS will be given in compen- back, enthusiasts of this new field have had to sation for each accepted item. If the fight for whatever meager knowledge they author of the wrinkle is already a have been able to obtain. This maga- subscriber, his subscription will be ex- tended one year or he may accept a zine, then, comes as manna to the in- one year's subscription to Science and information- hungry fan. It is our Invention or Amazing Stories, both purpose to keep these enthusiasts published by the Experimenter Pub- lishing Co. constantly informed, through "TELEVISION," of each new development. The second issue of "TELE- Dealing with Interference VISION" is now on Inside the Building the newsstands. THERE is no doubt that the following You will find be- bit of information has been anxiously sought by many a harassed listener. Our low a partial contributor chanced upon a case where it In the Television field there list of its in- The first Television maga- was necessary that the set be located in a are all of the thrills that the teresting zine was published by the foyer which was within a few feet of an radio fan knows so well. Get EXPERIMENTER PUB- elevator, bringing about interference from on the band wagon with your con- LISHING COMPANY about that source, subsequently most unpleasantly fellow enthusiasts. Be the tents a year ago. Over 50,000 apparent. After much moving about it was first in your neighborhood to copies of this magazine, in- own a television set. Obtain a "TELEVISION," have since discovered that circumstances about the copy of "TELEVISION "; been sold. This, alone, is terior decorations made it quite impossible it will show you how to build sure proof of the popularity to place the set anywhere but in the foyer; a real Television receiver. of this interesting new art. whereupon invention as the child of neces- sity was called upon, with the following re- sults: Partial List of Contents An antenna coil was substituted for the New Jenkins Radio Movies Practical Demonstrations Scheduled for Station WRNY New Belin Photo Transmitter Campbell Swinton Television System loop and carefully shielded an outside Vacuum Cameras to Speed Up Television Quartz Crystals Synchronize Television Sets aerial erected as far as possible from the Infra -Red "Eye" Sees at Night Baird Optical Lever Increases Speed Valersi Television Recording Pictures with Air Jet elevator. 'l'he lead -in consisted of BX (ar- Connection of Photo-Electric Cell How to Build a Radio Photo Recorder mored) cable, which was placed under the and many other articles of equal interest floor, and used only as far as necessary to get outside the zone of interference; the surface of the cable was grounded. This AT ALL THE25CCOPY OR WRITE method was employed on an extremely sensi- NEWSSTANDS DIRECT tive superheterodyne, and no doubt will function equally as well on the average re- EXPERIMENTER PUBLISHING CO., INC., 230 Fifth Ave., New York, N. Y. ceiver. The only precaution necessary is to make sure that enough BX cable is used to EXPERIMENTER PUBLISHING COMPANY, INC. get outside the zone of interference, the 230 Fifth Avenue, New York City, N. Y. limits of which may he found by testing the Gentlemen: Please forward to me a copy of TELEVISION. Enclosed find 25 cents receiver in various positions throughout the home until the position is found where the Name noise is no longer picked up; it may then be taken for granted that this is the limit of Address City State the zone. -Edward R. Jahn*. Please say you saw it in RADIO NEWS
www.americanradiohistory.com 676 Radio News for January, 1929 " Foolish " Questions (Continued front. page 610) 8POPULAR, May, 1928, issue), and can be conveniently saved for reference. The constructor who keeps such data handy will not be under the MODERN necessity of writing in for data on coils to use in a new circuit.
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The Play Girl flexible durable ma- ditions, a good knowledge of the tuning color "stills" of an of the receiver, and saintly pa- actual scene from the 29. The Man Who terial. These books temperament photoplay. Don't hesi- Laughs tience, must eventually be rewarded with are undoubtedly the desired "DX," as reception of stations tate. Mail this coupon 30. now. Every story The Hawk's Nest one of the greatest at an unusual distance is called. based on an actual 31. Streets of Shanghai values ever offered moving picture tri- WHAT IS AN "A.C. TUBE "? umph. The greatest 8 BOOKS FOR $1.00 at this amazingly book bargain of the Your Choice low price. Question: "Does the 'A. C. tube' operate age. entirely on alternating current?" Answer: No. Alternating current is Write Now! Don't Wait! This bargain cannot last long at this price used only to light the filament, or the "heater" element which heats the filament, CONSRAD COMPANY, INC. depending upon the design of the tube. As the modern A. C. tube requires anywhere 230 FIFTH AVENUE NEW YORK, N. Y. from one and a half to fifteen volts of al- ternating current to heat the filament, it is necessary to "step down" the usual 110 volts CONSRAD COMPANY, INC., 230 Fifth Avenue, New York, N. Y. of the house line by means of a small step - Gentlemen: Enclosed find $1.00. Rindly send me the books listed by number herewith: down transformer. However, to supply the Number+ "plate" voltage, or "B" voltage, direct cur- from a "B" socket -power Name rent, obtained unit or from batteries, must be used. Address Because receivers today use plate volt- City State ages ranging as high as 400, it is necessary that the 110 volts obtained from the house line be first "stepped up" to the required A REAL SPECIAL OFFER!! ---'1 voltage. After this the increased current -- must be "rectified" from alternating to di- t NI- RECTRON POWER AMPLIFIER rect current, as the receiver cannot function Ideal for use with Dynamic Speaker.) With alternating current on the plates of the tubes. After rectifying the increased cur- Model AP -935 As the Uni -Rectron stands The UDC-210 super power rent, we find that there is still a noticeable it is a super power ampli- amplifying tube and the hum present in the speaker, due to the char- fier, which can be used in UX -216B or 281 rectifying connection with any radio tube are used with this am- acteristics of alternating current. This hum set and loud speaker. Bind- plifier, which cannot over- is "ironed out" by an apparatus known as ing posts are provided for load. From the faintest input to the Uni -Rectron whisper to the loudest crash a "filter " -a combination of condensers anti and output to the speaker. of sound -R. C. A. Uni- choke coils. The entire combination of the Rectron amplifies each note Requires no batteries for its at its true value. High and step -up transformer, rectifier and filter sys- operation. It obtains its $88.50 low notes are all treated make up the "B" voltage-sup- power from the 110 volt. List Price alike. The volume tem goes to 60 cycle alternating (without tubes) and quantity deliv- ply unit, without which no radio receiver current lighting cir- ered will be a revela- case of a modern A. C'. cuit of your house. tion. can operate. In the Special - $19.75 ea. set, this unit is incorporated in the design Every one new and packed in original factory carton of the set, so that it is really an integral AMERICAN SALES CO., 19 -21 WARREN ST., NEW YORK CITY part of the receiver and is usually so con- sidered. Please say you sat.:, it ir. P.lnln VI?id1.0
www.americanradiohistory.com Radio News for January, 1929 677 RADIO DIRECTO1ZYl RADIO - Send for This Vie have a new illus- LITE - trated catalog showing our up - to - the minute TENNA stock of kits, parts and sets - everything you Moisture -Proof Extension Cords want in radio -all at Write for details dealers' wholesale Prices. Btrnbach Extension Cords permit PER -CON RUMP GROUND Write the Loud Speaker to be moved to A perfect efficient and noiseless today for Catalog any roost in the house. Attaches ground. Consists of three sec- "13-3." instantly. Install a Ifirnbarh Cord tions. Drive one at a time. Easy and put an end to distortion so to drive. Any length required. ALLIED RADIO ACCUSTI -CONE often due to badly insulated cords. Contact point copper. to which is CORPORATION (Double Diaphragm) Your neighborhood dealer has these oldere,l lead -In wire. Drive in Aeroplane Cloth Speaker 711 W. Lake St. ra- sizes in stock: 10 -20- 30.40.50 -100 basement or in close Places. Truly a rmolutionary step in Catalog. AERIAL INS. CO. Dept. "B -3," Chicago, Ill. dio reproduction! Send for catalog. foot lengths. Send for PER -CON MFG. CO. Richmond Indiana GREEN BAY. WIS. Accosti -Cone Laboratories BIRNBACH RADIO CO. One No. Seventh St., Phila., Pa. 254 W. 31st St.. New York
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The human SPEAKER TABLE ear could not detect Beautiful Col- onial design. further Solid walnut, tone im- hand rubbed. 200,000 provem e nt Size. 30" x 12 %" and 31" than is high. Made given -s with Temple RADIO NEWS readers by Air - Chrome s Baker or for dynamic speak- er. This is only one of many carefully scan the RADIO DIRECTORY every month. Samson Symphonic beautiful Fritts creations for Transformers t ris year. Write for full Your product here, at the lowest cost in the world's anlcul rs and free catalog. Send for full information D. H. FRITTS & CO. largest and most widely read radio magazine. 604 Hearst Bldg., Chicago SAMSON ELECTRIC CO. No order for less than three insertions accepted. Canton, Mass. SEND NOW Write for information. for New 1929 WESTERN RADIO'S CATALOG RATE PER ISSUE LATEST and FINEST, nationally known A.C. $25.00 sets, consoles, cabldets, speakers and accessories at LOWEST PRICES. Catalog sent FREE on RADIO NEWS request. WESTERN RADIO 230-5th Avenue New York City MFG. CO. Dealers, write for catalog. t28 W. Lake St. W. C. BRAUN CO. i Dept. RNCI Chicago 552 Monroe St., Chicago .. NOPHONIC LuNb RADIO TUBE CABINETS TELEVISION Our une In- CAPS cludes twenty Kits and Parts Stop That different Completo re- BRAIDITE models. ceivers assem- Howl: There is a bled in 15 Hook -Up Wire suitable salmi- Tn get the net or table minutes. 5 best from "The Braid Slides Back" models from for every set up. your set.be Make your connection, solder and every re- 537.50 sure that it and the insulation slides quirement. DISCS .,.j ; ÿ right back Into place. Write f o r MOTORS II,i 07Q0 e ml pl If your dealer cant supply complete il- HEAVY DUTY NEON TUBES Nophonic Tube Caps. Stops order treat lustrated "B" POWER $18.50 AMPLIFIERS of t - all vibration the filament. 25 Ft. Solid, 30e catalog. Complete with Tube. Delivers up and other parts List Price 25e 25 FI. Stranded, 35c I. A. LUND to 180 volts on any set. Dry Ask your dealer or serve direct CORP. o liquids. for - Write for Catalog CORNISH WIRE CO. Write literature. Insuline Corp. MERTZ SPECIALTY CO. 32 Church St.. New York 1018 S. of America 1306 Stockton Street Wabash Av. Model 5, Walnut FERBEND ELECTRIC CO. 78.80 Cortlandt St.. N. Y. C. Wilmington. Del. CHICAGO Price 525.00 425 W. Superior St.. Chicago, Ill.
Set Builders! Migrs.! Experi- SEND FOR NEW menters! Save Jobber and Television Tubes Dealer Profits by Buying Balkite Radio This marvelous new RADIO BOOK Direct In cabinets by Berkey & Gay Raytheon Ktno- QUALITY A. C. Filament Lantp. which radio All the new hook -ups. Transformers - Input; all engineers rail the types 115 volts, 60 cycles. greatest develop- Parts, supplies, A.C. ment In television, RCA -Supplies six 2265, two is now in stock. sets, television, short 227s, and two 1715. Be he first in your DE JUR wave, etc. ARCTURUS -supplies nine u locality to build a VITREOUS ENAMELED orless Arcturus 15 -volt tubes. television receiver. POWER RESISTANCES Write for free copy KELLOGG -supplies ten 3- Send money order volt filaments. NOW. For "B" eliminators, power ampil- now. State typo wanted. Bers and electric sets. Tease resist- List price $8.00. $7.50 ances are backed by 16 Years of con- "ÿ tinuous, the Factory to You Price... satisfactory service to 53.90 prepaid. Newark Elm. Co. Milo public. Write for =Woo. 226 W. Madison St. Quality Transformer Co. Fansteel Products Co., Inc. Chicago. Ill. D.JUR -AMSCO CORP. lia Canal Sta., Chicago Box 135 Oak Park, III. 199 Lafayette SL, New York, N.Y NORTH CHICAGO, ILL.
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 678 Radio News for January, 1929 Color Television Potter (Continued from page 633) TJ\\\ the width of the sideband, let us think of Condensers the picture as composed of a great number of unit areas. For a picture of a quality THE selection comparable with half-tone engravings, about . of leading 10,000 areas or dots per square inch will be manufacturers for necessary. The larger the screen, the more the finest radio are the elementary areas necessary for the receivers. Insure same fineness of texture or grain. This INTERNATIONAL the operation of means that a great many more unit areas Short -Wave Converter your radio set or must pass before the aperture each second Will Add Thousands of Miles power amplifier for a large picture than for a small one. To Your Receiving Range with Potter con- Now it is evident that, for each two suc- Broadcast reception on short waves is re- densers, which are cessive areas passing before the aperture, markably clear and free from static. Pro- known for their quality- uniformity- the photoelectric current will pass through grams are brought in from greater distances economy. with the utmost simplicity of control. long life- one cycle of change; that is, the greatest You can easily build the Aero International -2900 Condenser Block possible variation in current will be pro- Short-Wave Converter and receive short- Potter T wave programs on your present set. No for the single 250 type tube am- duced by the change from a unit of solid changes in wiring necessary. Just plug into plifier- $20.00. color to one completely dark. According to detector socket. AERO KIT No. 9 ;38.90 Potter T -2950 Condenser Block engineers of the Bell Telephone Labora- 250 type tube necessary to be THE for the push -pull tories, the highest frequency "STANDARD" ampi ifier- $22.50. transmitted per second is equal to half the No extra tube Is Block number of dots or areas scanned per sec- needed for this Potter T -2098 Condenser Aero Short-wave for the single 210 type tube am- ond; any change smaller than from one area Converter. Plug into detector sock- plifier -$20.00. to another is too small to be of consequence. et of your receiver The 50 -line picture used by Bell engineers and insert the tube Potter T -280 -171 Condenser which you re- required a transmission channel of which moved from set Block for a power -pack with 280 intotheConverter. type tube rectifier for a 171 type the highest frequency was half the unit -fre- Kit is complete with all parts. Can tube power tube -$18.00. quency of 40,000 areas per second, or 20,000 be assembled In a few minutes. For Potter by -pass and filter condensers cycles. Actually, an even narrower channel A.C. or D.C. re- was found to give satisfactory results. Now, ceivers. are available in all capacities and Price -- 532.00 working voltages. with a system whereby each line is succes- sively traced in the primary colors, the num- Write for information eboa! !he Nor' 1929 Acre Green Boot Potter Interference ber of fluctuations per picture would be tripled -and hence, the width of sideband. E ?DPP 0UM Eliminator The same would be true of the others, espe- INCORPORATED L Enjoy radio broadcast programs cially of the prism method last outlined. Dept. 119, 4611 E. Ravenswood Ave., Chicago, ill normally spoiled by interference from Here is room for much experimentation; oil burner, ice machine motors, fans, will it be necessary to scan each line suc- violet rays, vacuum cleaners, etc. cessively in each color, or to complete a Simply connect a Potter interference picture in one color before beginning an- Eliminator to the line circuit at the other? Will the speed of scanning need to DRESNER Shielded point where interfering device is con - be greater than that of black- and -white nected and your troubles will be over. television, or would a lower speed prove SHORT WAVE satisfactory? Experiment alone will tell. CONVERTER
WIDE CHANNELS SCARCE rOTTER1 165° The use of a sideband wider than 5,000 Completewith cycles is prohibited by the regulation pre- r L. scribing ten -kilocycles separation between COILS broadcasting channels. Technical difficul- l ties also make the use of an extremely wide The sideband difficult. Modern receivers now Only Set with a Wave. represent a compromise between selectivity length Range The Potter Co. and quality: that is, a receiver must sepa- 15 to 550 Meters North Chicago, Illinois First time offered! New modehrompletely assem- rate stations ten kilocycles apart without bled; may be used on any set ; built in beautiful A Nòb,ul OroarAnaloe N ron *rare mahogany finished metal cabinet. Highest efficiency cutting sidebands. A set which is tuned at amazingly loin price. Gets. stations broadcast on short waves by many powerful stations throughout sharply to 1,000 kilocycles practically re- U. S. and Europe. jects frequencies of 1020 kilocycles. What, If your dealer cannot supply you. send money or- der direct and we will ship at once. Guaranteed. then, if the sideband is widened even more (when ordering unit. be sure to specify whether than that required for ordinary television? it is to be used on AC or DC set.) DRESNER RADIO MANUFACTURING CORP. Everything in A single receiver can respond to frequencies 640 Southern Blvd., Dept. RI, New York, N. Y. of only a limited width without attenuation Radio at Wholesale of the higher frequencies, which means We supply every radio need from coarsening of grain and loss of detail. Sin - our mammoth stock of kits, gle- sideband transmission, much advocated BUILD THE ALL-ELECTRIC design. parts and sets of latest as a panacea for the crowded conditions SCOTT SHIELD GRID 9 Lowest wholesale prices. Expert Now this famous 9,400 -mile receiver is offered -ALL- prevalent on the broadcast waves, is much ELECTRIC! Build it in four hours -and dial your sta. attention; immediate service. Lions from world -wide radie. Practically unlimited in Write for big, illustrated Cata- too complicated for general use; as are also range, the Scott "Nine" challenges any existing set to equal it in volume. tone. selectivity and extreme sensi- log "B-3." double- modulation schemes and others tivity. Get facts today, including FREE circuit diagram, which require an accuracy of adjustment DX verifications, etc. beyond the abilities of the average listener. SCOTT TRANSFORMER CO. Allied. Radio Short waves offer a less difficult problem, so 4448 Ravenswood Ave. RNI CHICAGO, ILL. far as the problem of sideband is concerned, 711 W. LAKE STREET, CHICAGO for at 1,000 kc. (300 meters), 20,000 cycles derive largest profits know and constitutes a 2% sideband, while at 4,000 INN j (34 heed certain simple Insure your copy reaching you each month. Sub- íi but vital facts before scribe to RADIO NEWS -52.50 a year. Experi- ke. (75 meters) it is merely / of 1%. But applying for Patents. Our book Patent -Sense gives those menter Publishing Co., Inc., 230 Fifth Avenue, short waves are already facing a con - facts: sent Lee. Write LACEY & LACEY. 631 F St. New York City. the Washington, D. C. Established WO Please say you saw it in RADIO NEWS
www.americanradiohistory.com Radio News for January, 1929 679
gestion hardly less acute than that on the higher wavelengths. When television is perfected to the point that it no longer requires studio lighting conditions, one of its chief values will be as a field reporter of important events. Chain broadcasting, also, will be highly desirable. Both of these require telephone circuits for long- distance connection. The limits of present long -distance wire transmission cir- cuits do not allow the use of a channel wider than 40,000 cycles. Thus a large panorama, such as a football game, pag- eant, or any large spectacle would neces- sarily be reduced to a small size, or else detail would be negligible. To be sure, the frequency range can be divided; so that dif- ferent wide circuits might transmit various portions of the spectrum, the sections being separated by band -pass filters for transmis- sion and re- assembled at the receiver. But the expense and the difficulty of such ar- rangements would be tremendous. Radio re-transmission from field cars is perhaps less expensive, but no less complicated, to say nothing of bugbears such as selective fading, static, etc.
THE EYE AND TIIE CELL AmerTran DeLuze Audio Transformer, Standard of Excellence rrr Stage; Turn Ra- So, 3: Sod Sage; Turn Ratio, .i. Price, each A peculiarity that will perhaps need to to.oc. be compensated for in design is the distor- tion resulting from the response- character- istics of the photoelectric cell; i. e., the se- AMERA&N
. lective effect mentioned early in this ar- ticle. Since the photoelectric cell is not uni- formly responsive to all colors, certain por- Quality Radio Products tions of the picture would be overempha- sized; thuus altering the relations between Standards of Excellence for Radio Reproduction colors. This distortion might be compen- sated, either by the use of a number of HE real worth of any radio set depends upon "tone quality" photoelectric cells of differing characteris- T-the ability to reproduce music as it is broadcast from the tics, or optical means, such as regulating the studio. The problem has never been one of refining the radio transmission properties of the transpar- encies used for coloring. frequency amplifier -it has always been the manufacturers of An interesting physiological question sug- audio systems who have had to develop their products to reach gests itself with regard to the visual re- the pinnacle of natural reproduction. sponse to color television. The nerve cells of the eye which respond to light waves arc Long before broadcasting was thought of, The American Transformer Com- of two kinds, the "rods" and the "cones." pany had gained a reputation of manufacturing quality products. Since the era Color vision is accomplished by the cones, of broadcasting, this company has occupied a unique position in the develop- light and shade by the rods. How quickly ment of quality products for radio reproduction. AmerTran products have do the cones respond to color changes? This been considered too expensive for set manufacturers to use in their commercial element might affect considerably the speed receivers, so it has developed a clientele of set builders who want, first of all, necessary for color television. natural reproduction. A set receiving pictures in color would produce queer effects if slightly out of syn- AmerTran products are never AmerTran ABC Hi -Power Boa -3cc chronism with the transmitter. A picture built down to a volts DC plate voltage, current up to "out of frame" would also be price -the procedure has to ma; AC filament current for recti- out of the fier, power tubes and sufficient t,5 and right relation with the coloring disc at the always been reversed - 17 AC Tubes for any set. Adjustable transmitter, and good bias voltages for all rubes. Price, east of hence, the order of the "How can it be Rockies -less tubes- 595.co. colors would be transposed. Our favorite made -then reduce the soprano might surprise us with a blue face, cost by applying econo- red eyes, green lips, and white hair. Static mies in manufacture." would show up as a purple blush or á row roducts page are of yellow dots sweeping across the screen. The shown on this Any transient variation in atmospheric con- but a few of the thirty odd AmerTran ditions would throw the colors out of their devices in the field of radio reproduction, correct proportions. This latter effect would each of which has attained the degree probably be slight; because a momentary of perfection necessary to be introduced discoloration would be quickly covered up as an AmerTran product. The facilities as the scanning beam swept over the screen of our engineering department are at again, smoothing out and concealing the the service of every one interested in discolorations: better radio reproduction. We will an- A phenomenon that has caused noticeable swer to the best of our ability any distortion in television is the so- called "en- question in the audio or power fields. AmerTran Push -Pull Powe velope delay," which is due Stage(iliustrtted above)-com- to the difference pletely wired with input trans- in time required for currents of differing former and a choice of 4 output frequencies to traverse the filters and vari- transformen depending on American Transformer Company speaker aodpower rubes. Adapt- ous circuits encountered in transmission and able to 17t rt am tubes. cones reception. Transformer Builders for more than 28 years or dynamic t-pe speakers. A group of closely -related fre- Price, east of Rockies -less quencies suffers a distortion of wave form 30 Emmet Street Newark, N. J. tubes-536.00. because of the altering of phase relations Push -Pull Amplifier, ABC Hi -Power Box and Push -Pull Power Stage licensed under between the various frequencies. With color parents owned or controlled by RCA and may be bought complete with tubes. Picase say you saw it in RADIO NEWS www.americanradiohistory.com 680 Radio News for January, 1929
television, this would not only result in dis- tortion and poor resolution of images, but cause an aberration from the true color re- BUILD YOUR OWN lations. Bell engineers have compensated Exponential Horn this distortion by balancing against it an- This man clous 1T.r21 -In. exponential born with a other distortion opposite in its nature; that 90 -In. air column can be easily built of ?á -in. is, what is called "aperture distortion." soft wood by any ama- The newest radio wrinkles -A-C, grid tube. After the edge of a single hole of the scan- teur. It produces the short wave, television, dynamic speakers, most wonderful t one newest tubes and circuits- anything and ning disc cones opposite an illuminated Quality. We furnish you with a set of FULL- everything in radio -are now ready for spot, more and more of the hole gradually SIZED PATTERNS, you at Barawik's. With elections, foot- permits the passage of light; that is, the which have been accu- ball, National broadcasting, Rosy and rately and scientifically hole does not fall into position instaneously, worked out according to other big doings filling the air, thou- the exponential prin- sands of newcomers will take to but gradually, and as a result, the photo- ciple. Simply aw ut radio this year as never before. Busi- given image -area the wood to theaize ness will be good-Set builders electric current from a and shape of the pat- will terns and nail and glue make money. You can clean up big builds up gradually instead of rising to its together and you have by Buying from Barawik -the old- full value instaneously. In color television, the latest and est, biggest, most reliable radio will this compensation be possible? Experi- MOST EFFICIENT TONE PRODUCER house in the world. Let us prove it. AN IDEAL XMAS GIFT Send now for the will Big Cook -all ment alone tell. Send $2.00 for a set of these full -sized ready for you patterns and -free. Get the latest Lest he be misunderstood, the writer complete instructions. or we can furnish you the radio information and lowest prices. COMPLETE KIT. which Includes the wood eut to fit, wishes to make clear that he does not be- the nails, the glue, our large -sized CONCERT UNIT. and full Instructions. All complete with postage pre- lieve it likely that practical television in paid for $11.75 in the United States and $12.15 in BARAWIK CO. Canada. si natural colors will be possible tomorrow, B CANAL STA., RADIO PRODUCER CHICAGO, u.s.A. that next year's television receivers will be COMPANY 1245 teffersge Bldg. Peoria, III. This Big Book Sent provided with color attachments such as de- to You Free scribed above. He floes maintain, however, that, when the obstacles above sketched are TUNE IN ON THE SHORT WAVES Name overcome, and television on a commercial scale is actually accomplished, color tele- Ki- Lowave Address vision will represent merely a refinement of detail, a further development along the same Adapter City lines that make universal television possible. Can Be Used on Any Set. If a picture of 240,000 dots per second can Price $19.50 be successfully transmitted in black -and- Very simple to attach. Furnished complete with white, surely our engineers can produce a 4 plug -in coils, wavelength range 14 to 210 meters. Instantly converts your present set into a Short -wave set picture of one -third the size in three colors. by simply inserting Adapter plug in place of a tube, n extra tubes, batteries, etc., required; no changes in wiring It seems hardly likely that television will of set necessary. NE W! 90 Volt be applied on a universal scale until some REACH OUT. Hear the U. S. and Foreign Short-Way Stations as many others are doing. The thrill of listen- overcomes the chief difficul- ing to real DX reception is yours with Ki- Lowave Adapter major advance attached to your set. ties mentioned above; but when such an ad- Very neat and compact In size, dimensions 7 %x7%x36 Inches, contained in a beautifully piano- finished cabinet, Power of the with make Unit vance is achieved, the possibilities its bronzed etched illuminated vernier dial it a handsome addition to any set. Complete instructions fur future seem unlimited. Meanwhile, tele- niched with each Adapter. Fully Guaranteed. \\men ordering specify whether for AC (All Electric) a vision rests upon the knees of the gods. DC (Battery or Eliminator operated sets). Price $195 postpaid anywhere. Enclose express or money order. or if you prefer send $1.00, with order balance C.O.D. plus postage. KILO RADIO CO. 1722 Palliator, Detroit. Mich. A "Wireless" Relay A CURIOUS contrast to American meth - 1-11. ods is shown by a dispatch from Be- ziers, France, stating that its broadcast The FUTURE station has been hindered in an endeavor By to present programs, by remote control, Positively Eliminates from the Roman amphitheatre in that city, Professor A. M. Low Hums, Line Noises, etc. $ 12.75 through the refusal of the "P.T.T." (French Greater and telephone monopoly) to allow Volume governmental "THE FUTURE" is one of the most Clarity Guaranteed the use of telephone lines for the purpose; remarkable books of the age. Professor Non -acid and noiseless. All detector and Intermediate and the Beziers broadcasters will be com- Low, the author, is a scientist of interna- voltages plainly marked. Simpler to hook up than dry cells. Operates 1 to 12 tubes. If not thoroughly satis- pelled to fall back on a short -wave radio tional reputation, also an experimenter fied return atter using 30 days for complete refund. the in the many branches Guaranteed further 2 years. For 110 -120 volts A.C. 25 relay for the purpose of getting pro- and inventor of to 60 cycle current. DO volts, $12.75: 11235, $15.25; gram to the studio. science. This book written by him has 135, 517.50: 15735. $19.50; 180. $24.00: 20235, 325.00. Also built for D.C. current 110 and 32 volts at only aroused wide -spread interest. It deals $3.00 additional, any size above. Ample stocks -same with the world of the future, certainly an day shipments. Simply say-ship C.O.D. or write for my interesting literature, testimonials, etc. unusually absorbing subject. Written in A Couple of Ear Twisters the popular, non -technical fashion, "The Future" reveals the many advances B. HAWLEY SMITH WI-IAT words do you think would be and 334 Washington Ave., Danbury, Conn., U.S.A. and re- changes that are in store for humanity in the best to test transmission a. new life to come. ception? In the Bell Telephone Labora- This book has received favorable com- tories, where telephones are tested, two ment in book reviews the world over. Do sentences are repeated over and over by not neglect to read this treatise on the phonographs: "Joe took father's shoe bench future by Professor A. M. Low. It is a out," and "She was waiting at my lawn." literary treat for everyone, who can get these across This Wholesale The radio "ham" Mail your order now! Don't wait, every- by phone to his fellow- workers may know body is reading this remarkable book. Catalog that his modulation is good. Will Save You Money Price -$2.00 Write today for our large illus- new "B -3," show- trated Catalog FORCE OF HABIT Experimenter Publishing Co. ing how this organization of men 230 Fifth Ave., New York, N. Y. in Radio HAMLET (bitterly): "This bunch out in Gentlemen: Enclosed find check or money with years of experience order (check which) for $2.00. Kindly send me a can give you personal service. front tonight must be a crowd of radio fans." copy of Prof. A. M. Low's new book "THE FU- POLONIUs: "Why, what gives you that TURE: notion ?" Name sit there HAMLET: "Because they just Address like Stoughton bottles and don't give you City State 711 W. LAKE STREET, CHICAGO a peep of applause!'- (31iss) Micky Burke. Please say you saw it in RADIO NETT'S
www.americanradiohistory.com Radio News for January, 1929 Television's "Last Touches" (Continued from page 636) beginning-or end -of each image, thus interrupting the reproduction slightly. This period may be used to send a synchronizing signal which will correct the rotation of Best For both disc and mirror gears. There is nothing, of course, to prevent the use of three or more mirrors, backed at equal angles against the revolving shaft, and their re- duced curvature would lessen distortion. However, in all these systems discussed, whatever we gain in improved results, we pay for in additional electrical and me- chanical complexity.
PROBLEMS OF DISTORTION By separating the drive of the disc and the mirror, we introduce complexity, but we gain flexibility. For instance, suppose our disc has 48 holes. We desire to receive a 36 -hole transmission which has a speed of 12 images a second, or 720 a minute. fur disc revolving 9 times a second, or 510 times a minute, will sean the picture TONATROL with the salle rapidity; our pair of mirrors .L -mark revolving 360 times a minute will direct Exclusively Licensed by Teeh- nidyne Corporation Under A Complete Line of Volume Controls the rays from top to bottom of the screen U. S. Patent 3G53, 1034104 Controlled volume means improved toue. Tonatrols in the sanie titile as at the transmitter. 34103, control volume perfectly, adapting reception to the 'l'he shape of the image may be slightly occasion and personal tastes. They come in types to meet the specific requirements of all circuits - distorted, but the action will be dearly battery or A.C. power -in standard types, or with recognizable. filament or power switch attached. $1.50 to $3.00. We cannot escape a certain amount of distortion, caused by each reflection or refraction, although the skill of the optical TRUVOLT Reg. Pat. designer may succeed in limiting it. For U. S. Oa. instance, the disc and the mirror are re- ALL -WIRE RESISTANCES volving simultaneously; the mirror will Unexcelled for voltage control in 11-Eliminators. Made with throw the course of each line down, toward a high factor of safety to carry much homier current loads. Trurolt Variables simplify B- Eliminator construction by the side of the image which the light -spot eliminating difficult ca leu lot Ion and making all adjustments reaches last. If this corresponds to the easy. 22 stock sizes -$3.50 each. Trurolt Fixed Resistances are adjustable to different set condition at the transmitter, where the values by the use of sliding clip tans -an exclusive Truvolt feature! Made in all desirable resistance values and cur- selection of spots scanned is made at a rent ratings. U. S. Patent 1,676,859 similar angle, the picture will be correct. and Patents Pending Electrad specializes in a full line of Controls for It may be suggested by the ingenious all Radio Purposes including Television. reader instead of a disc, we have Mail coupon for full information. that, -CUT HERE a perforated plate sliding back and forth, ELECTRAD, INC., Dept. N -I, 175 Variek Street, New York. movement shall turn the Please send me descriptive circulars on the following products and put and that each mo un leur mailing list for similar literature. mirror through a predetermined angle, as ....General Circular ....Tonatrol Volume Controls ....Plsasatrols the carriage lever of a typewriter turns ....Royalty Variable Resistors ...Truvolt Divider ...."Electrad Control Manual" (enclose 10e. for mailing) its platen. This would be an obvious sug- ...."What B Eliminator Shall I Build." (enclose 10e for mailing) gestion to adopt at lower speeds, such as I am particularly interested ln we might use to transmit a still picture; Name -100 so, Ind, at speeds of 2, a second or Address ordinary mechanical devices fail. Even the Sr= greatest concentration of light may not make it possible to produce a scanning disc capable of being revolved safely at a speed as great as we may require. That is why televisionaries are looking forward to the development of some undiscovered proper- ELECTRAD ties of matter, or the adaptation of those which have not been hitherto used for the purpose, to obtain an enormous speed of image- scanning without the use of me- t hanical parts. Again, as shown in Fig. 2, we encounter the problem of the ambiguity of image impulses. This, however, will be overcome by the increasing speed of transmission, 'Radio's largest-' and the inaccuracy of the eye itself- another of those mechanisms which rejoice hit supply house POLK in complexity. Each of its defects will ESTABLISHED YEARS BINDING POST counterbalance one in our television ap- 30 Insulated. No holes to paratus. We Have Complete Kits For All Circuits fish for. Insert wire in any position. Quick ac- There is, as we said before, always a Now appearing or which have appeared tion and holds tight. certain amount of distortion introduced in "Radio News" and other publications. Standard markings. when we cast a ray obliquely on a fiat Send for Circuit Booklet &Catalog J. L. POLK Ave. TROY, N. Y. surface. Suppose that the rays at their M. & H. Sporting Goods Co. fullest extent cover nearly a right angle. 512 Market St., Phila., Pa. I Please sap you saw it in RADIO \TETVS
www.americanradiohistory.com 682 Radio News for January, 1929
Books no Home should be without
HOUDINI'S SPIRIT EXPOSES the hair, the eyebrows and lashes adding that extra pound or taking off and excessive weight -all is covered. DUNNINGER'S PSYCHICAL BEAUTY SECRETS should be every woman's constant companion at INVESTIGATIONS 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 Per Copy guise of the living dead. 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 Alt sions drawn from the various success- Walter B. Gibson has written what ful exposés of Houdini, together with is conceded to be the most complete the tremendously interesting revela- book of card tricks ever published. tions contained in Dunninger's Psy- There are literally hundreds of these chical investigations, make this 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. Once you have mastered a few of the Per Copy 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 25c you have learned the simple secrets of type." It is the purpose of this book Per Cops 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, 0r04 PNq. ,osteós EXPERIMENTER PUBLISHING ) IInc. 'I!lyGÓgí+ ctets CO trl -j $e g4 Vti., eoai 4 230 Fifth Avenue és TY A cbea SeQegQesgb '° 1tiv1FZ' c ot kt oxs oe á.çtt New York, N. Y. tbeb4a9ápïs ce .. .. gYg23e9: toOgóyo4° Stete . 010 ' erS óeso gese Please say you saw it in RADIO NEWS
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Then the ray at the margin of the picture will spread out to a width about double that of the ray at the center, or four times its area. This is not a grave fault when the image NORDEN -HAUCK at the transmitter is scanned at the sane E angle. In that case, the television is finer NEW 8 TUBE in detail at the center than at the margin of the image-exactly as in the ease of the same scene when it is scanned by the human AC ELECTRIC MODEL L eye. In order to see more clearly at one side or the other, the eye must turn -just as does the camera of the newsreel photo- FOR grapher. The televistician who takes the E "scanner" out of the studio for a job must develop a technique for most effective 1929 "pick- ups," just as his brother who "spots the mikes" has clone. Size 8x11x22 C with confidence that, We can now say Weight 35 to make television a domestic utility rival- lbs. ling the radio- phonograph combination and the electric refrigerator, there is nothing Wave length T lacking except the perfection of a few little range 200 to details of electrical and optical adjustments. 550 meters. If you have time necessary ideas to supply lv one or more of them, use "all due dili- gence" to perfectc t hem andnil getet y our "evi- The Norden-I (Hock Electrophonic is an entirely new nut superior broadcast Receiver dence of conception" in written forni right operating directly from house current. It is well built, handsomely finished and com- pact. Truly it represents the highest type of efficiency obi He in point of range, away; there a lot of other inventors on selectivity and simplicity combined with utmost quality of reproduction. the sanie job and working away for clear life. We shall be very glad to see your working model. 10 OUTSTANDING FEATURES ELECTRIC. The Electrophonic is all electric operated and self- contained. No Elimi- nators or batteries whatever. Employs standard Radiotron or Cunningham alternating P Loftiest Tower Planned current tubes. CIRCUIT. The Electrophonic employs an 8 -tubs, circuit; three stages direct tuned B1ltCl';I,ONA (Spain) plans the erection radio frequency amplification fully neutralized, detector, and three -tube tower audio of a 400 -meter (1,312 -foot) radio tower amplifier push -pull type. SHIELDING. The Electrophonic is totally shielded. Complete inter -stage shielding for its coming exposition. This would be the permits high amplification not obtainable otherwise. loftiest structure on the globe, exceeding SIMPLICITY. The Electrophonic has but one control for wavelengths, one control the Eiffel Tower by several hundred feet. for volume. Illuminated drum dial calibrated in degrees and in kilocycles. SENSITIVITY. The Electrophonic has carefully balanced radio frequency tuning 'l'he design gives it a circumference of six circuits which with superior quality of materials and workmanship combine to make hundred feet, and includes hotels, a theatre, the Norden-Hauck Electrophonic a long distance Receiver. o a muse and as SELECTIVITY. In the Electrophonic total shielding and carefully balanced circuits a library, as well the ra- and quality permit unusual selectivity so necessary in congested districts. dio transmitters for broadcasts and teleg- QUALITY. The Electrophonic is of the highest quality of construction and design raphy. throughout. Comparable only with costly custom built Receivers. FINISH. The Electrophonic has a exquisite solid mahogany cabinet, brown finish. N Heavy cast bronze escutcheon plate and tuning knobs lend to the rich appearance of the Receiver which will fit in any surroundings. Cabinet high French polish and full Cuckoo! Cuckoo! piano hinge. Rack removable and ventilated. GUARANTEE. The Electrophonic material and workmanship are fully warranted AVOTHER polyglot transmitter recently against any defects whatsoever. opened is Laibach, (Jugoslavia) on PRICE. The Norden -Hauck Electrophonic Receiver is moderately priced at $125.00. 570 meters, 2,500 watts, which announces Packed fur shipment. in Serbian, English, French, German and Italian. European stations identify them- selves by various distinctive sounds -musi- f. o. b. Phila. cal or otherwise -between numbers; and List Price $12500 "Radio Ljubljana" has adopted the cuckoo's COMPLETE illustrated literature gratis. Write, telegraph or cable today. note as its call. - INC., ENGINEERS MARRIAGE A LA MODE NORDEN HAUCK, JACK: "Was your wedding reception a MARINE BUILDING, PHILADELPHIA, PA. big success ?" Builders of the Highest Class Radio Apparatus in the World. .TILL: "You bet! Why, we got Hollywood on the loud speaker! " -Leslie Carpenter.
TRE RADIO SERVICE FREE TO SET BUILDERS AND DEALERS WRITE NEW 100 PAGE CATALOG TODAY HAMMARLUND OFFICIAL DISTRIBUTORS Send for large, new il- SILVER - MARSHALL KIT HEADQUARTERS NATIONAL COMPANY AUTHORIZED JOBBERS lustrated Catalog "B-3," AERO SHORT -WAVE AND DAVEN TELEVISION showing the latest of We are ready to ship all kits or parts produced by the above manufacturers as well as any others everything in radio at specified in any radio publication. wholesale prices. 31 Years of Service to the Trade ROYAL- EASTERN PAYS THE FREIGHT Radio Lowest Wholesale Prices AlliedCORP RATI ON Send for your copy of our catalog 711 W. LAKE STREET, CHICAGO ROYAL - EASTERN ELECTRICAL SUPPLY CO. 20 West 22nd Street, New York City, N. Y.
"That's o good sermon -" "Spades are trumps -and it's a grand organ!" Insure your copy reaching you each month. Subscribe to Radio News-52.50 a year. 1-- "Funkalmmnacl, 1928," Berlin Radio Exposition. Experimenter Publishing Co., 230 Fifth Avenue, N. Y. C. Please s a y you saw il itt R.-0nIC] NE rVS
www.americanradiohistory.com 684 Radio News for January, 1929 The Dark Side of Radio A MARVELOUS (Continued front page 641) MON EY- MAKI NG repay hint for the undesirable expenditure. Finish the Job! OPPORTUNITY He would have them all come in on the mor- -With a Carter row to listen to Nitrate sing her "Oh, Honey, Won't You Be My Sugar Man," sung Radio Outlet on to an audience of nearly 5,635,999 people. Plate. Fifteen Let his neighbors all know how important ' different styles Landlord Snigsbie was in the community. and combina- tAFJ4YETTF Now this is not intended to be a love story. A woman is usually the incentive tions planned to to a crime, and as the French say "Cherchez satisfy every pos- Electric la femme," Nitrate was the explosive as far sible condition. as our hero was concerned. He simply had to hear the voice of his adored, although Iona Specified and RADIOS unadoring, Nitrate over the radio. used by leading architects fYAgentc &Dealerr and contractors. The dots to denote a lapse of one day. Finish the job with a 30 DAY Scene: Landlord Snigsbie's parlor. It Carter Plate. FREE TRIAL seemed as though Snigsbie had invited half of the colored section of Harlem to witness Alert Dealers and Job- Get Hoe cony vl our his triumph. He would show his guests how bers can supply.
www.americanradiohistory.com Radio News for January, 1929 685
mad as a bull pup against every other member of that very worthy congregation. Lorelei Gatsby, whose only claim to dis- tinction was the patented liquid to remove the kink front the otherwise curly heads of her sister sufferers, which she had discov- ered. Lor' bless us! There's IIiram Kctchcm, the real estate magnate of vast proportion and circumference. He it was who created the slogan, "I Ketchetn Young. If I don't someone else will." 'ro his mind he was the wit of 1--Iarlem. Where there is ignorance there is bliss! 'ro come back to Lantllord Snigsbie's par- lor, and Snigsbie. Here he is standing in front of the radio set with deep palpitation of his heart. It was seven o'clock. Time for his "chocolate drop" to come on. 'l'he radio dealer had sent a boy for two hours yesterday to fix up the machine, and had told him exactly how to work it. Says he: "Putting 'em "Now \h. Snigsbie, vo-all gwine have a good time tomorrow night if yo' gwine do just as ali tells yo', and nothin' else but. through the mill" Now don't you go a- foolin' round this heal contraption until tomorrow night at 'xactly sehen o'clock, when yo' wants to hear yo' HAMMARLUND labora- and linen cable that drives the baby lamb croonin' to de honoble Snigsbie." tory and shop tests leave new Hammarlund drum dial And so he obeyed orders. The boy had nothing to guess -work. All withstood 363,600 full -range told him if he would turn the knob and put possible worry regret are of heavy, - the plug in, all would be well. Now was and movements a four the big moment. He inserted the plug, taken out of Hammarlund gang condenser - more than turned the dial. There was a tense silence products -their soundness is fifty years of normal use. only broken by a strange hum of the ma- proved before you can buy chine. Suddenly a voice, "This is Station them. And under such treatment, WBUM. You will now hear the "Honey is why "Ham - the condenser bearings, plate Blues" sung by the inimitable Nitrate Eliza That the name alignment and pigtail connec- Pepp of the "Lookin' Wild" Company. marlund" stands pre -eminent tions have ample opportunity Click. Then: silence; next, a voice. A sweet in the radio world for quality of to show up any weakness of feminine voice. It did sound like Eliza's. equipment that serves more design or workmanship. Snigsbie turns to his guests and in a "high faithfully and lasts longer than hat" manner smiles graciously and nods his you will probably ask of it. head to each one of his guests with an "I You can rely on Hammarlund know what a great man I am" manner. And In tests, made on the machine Products because reliance is then the feminine voice oozing out from the pictured above, the special silk built into them. body of the loud speaker: "Small Snigsbie, can yo' hear me? Ah knows yo' is lisenin' to me, so l'se gwine Fill in and mail the coupon below treat yo' to a few most choisest voids dat l'se been cravin' to expedite to yo' crami- COMPANY oO° aula fo' a long, long time. Colored ratan, HAMMARLUND MANUFACTURING o9F occ9. keep yo' ears wide open, for what l'se gwine 424 -438 W. 33rd Street, New York to say is dat yo' is so mean yo' would take Sbof _t1 de nails off a dead man's fingahs and use foc iAsr__ct+ 'eta fo' carpet tacks. Yo' is so low, yo' can put your shoes on standin' up. Yo' is a zO 1s° o c`t`ec niggah with a natual proclivity to do mean ammarlundPRECIS/ON things, 'cause they gwine mean nothin' to PRODUCTS Sc,see Gj`9 you. Yo' name is Small, but yo' is smaller o 5C8te den what yo' name gwine imply... . By this time, Landlord Snigsbie was fast n reaching the lunatic stage. His face was red with rage, and his voice and hands shook as if with a palsy. There were shouts of laughter which proved. so hilarious that BE A RADIO DOCTOR. three or four of the guests who were rock- ing hack and forth with such intensity that If you are interested in radio, the quicker you decide to make radio your the old and feeble furniture gave way and life work the sooner you will be assured of success and Big Money. they found themselves in intimate compan- a year is possible for men connecting at once ionship with the none too attractive looking with our big National Radio Service organi- $5,000 zation. floor. The room was in an uproar, but the I Need 1200 worst was yet to come. Snigsbie in his un- Men at Once for Chain Service Stations Don't be a "tinkerer," get in on the ground floor with a big WHY controlled wrath opened the door, and going proposition. Investigate at once. THE over to the radio, he pulled it out bodily, "Have a licensed Radio Doctor fix it" is the slogan where our by its roots, with the entangled wires hang- mea operate. RADIO ing limp and in disgrace. He flung it Write today for our free booklet, "Why the Radio Doctor" DOCTOR through the door, followed by the loud E. W. PARKER, Pres. RADIO DOCTORS, INC. h / speaker. As if to rid himself of this ter- Dept. N4, Essex St., Salem, Mass. rible demon with all its belongings, he grabbed one "B" battery after another and, Insure your copy reaching you each month. Subscribe to Radio News -42.50 a year with blasphemy upon his purple lips, threw Experimenter Publishing Co., 230 Fifth Avenue, N. Y. C. Please say you saw it in RADIO NEWS
www.americanradiohistory.com 686 Radio News for January, .1929 FANS: third big edition
Don't Over
Miss COMPILED BY THE STAFF OF 150,000 This Copies Big Already Issue Sold
ItXPERIMENTER PUBUShINO CO. 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 QUESTIONE AND today! Over 112 pages - fully I' ANSWERS the foremost work of its illustrated -large magazine size e kind available. There is a full and o 4C complete explanation of every worth- t while circuit that has appeared since 50c 4Q ,tiTt4, V ,-,,f,,,,-, the beginning of radio, not only the THE COPY co# sSe44 9tip " explanation, but also complete dia- 44' ASK YOUR NEWSDEALER yI ¿S J grams from which the set can be con- OR WRITE DIRECT ,SVe Cite9,c08$ EXPERIMENTER PUBLISHING COMPANY, INC. 4,,44 e ,t9 yFe 4 230 Fifth Avenue, New York, N. Y. ' P G` e
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it with a ferocity never before equalled by him, alongside the bruised and battered radio set lying helpless and forlorn some- where in the Clark and dreary hall. But not for long, my friends. For Ulysses Grant Rasbv and Sambo Brown, lurking in the dark recesses of that hall and still in the throes of some unaccount- able mirth, rescued the poor and blameless radio set from its disgrace. After a few hours of repair work it was properly placed on the table in Ul'sses' room. They Townsend " if Power Units connected it to the borrowed aerial that once upon a time-only that very evening - must belonged to Landlord Snigsbie. The plug Now in Use --they be good. in its proper setting, the dial turned, and then the catchy strains of the "Honey Blues" came pouring forth in all its glory from They ARE good! Besides full tone, clarity and LOI the silver throat of his beloved Nitrate, now volume, you get the thrill of startlingly clear long - fete distance reception. Never in radio history has any- broadcasting from a night club. thing given such sensational results for such a low price. UNSURPASSED QUALITY built in with money saved by unified production methods and low The rear of Uriah Jingle's drug store was merchandizing costs. New thousands of set owners filled with the gentry of the ivory. For learning amazing value of this Unit. once there was a lingering in ex- iuil the Plug light citing crap game. Bits of conversation. Utmost economy and convenience. into socket and forget it. Delivers up to 100 volts on any "I .or` almighty, dat sho' was puttin' one set on D.C. or A.C. -any cycle. YOU TAKE NO over Landlor' Snigsbie." Peals of laughter. RISK. Sold on real GUARANTEE -it must "Yo' all knows what dat radio boy done satisfy or money paid us will be returned. went an' done to Snigsbie's radio, alt APPROVED reckon? IIe jes' cut dat dere aeyial loose Fill in coupon and send with from de set, an' den ventrililoquism hopped SEND ONLY $1.00 only $1.00. Prove this marvel- and passed by the on de loud speaker an' did de rest" Hilari- ous value to yourself. Use it ten days. Then if it fails rigid laboratory tests ous laughter. to do everything we say, return it and money paid us of "Popular Radio" and "Radio News." "Sambo Brown sho' done give a good imi- will be refunded. Make a REAL receiver of your set. tation of Nitrate's voice, an' nothin' else but" From "An' say, brother, I'se gwine laugh until This Month's Mail I'se hear from Ulysses' own ivories how he Your Eliminator has been in use for two years at an average done went and done dat mean trick, and if of o hours a day on my 5 -tube Stewart- Warner and ant well he gwine come heah tonight, what say we eatisaed with it. Clifton E. Palmer, give him dis heap what you call "proceeds" Highland Park, \Itch. of this crap game. A11 brothers yo' in favoh Iiave had your Eliminator in say "ay" service for a year and it is still pr going strong. Three friends have also purchased one and are equally pleased. Walter P. Benisch. So. Pasadena, Calif. Your Eliminator tar superior to -B" batteries. Attached to my 5 -tube Radladyne it la as good as any All Electric set I hate In Our yet heard. January Issue: Leo Pfeffer, Alton, DI. The War of Have had your Eliminator in the Planets, by use for over 1-29. l arl Vincent. In this sequel a year and it has proven very satisfactory. TOWNSEND o "The Golden Girl of Munan," Irving J. Scherer. the author outdoes himself. LABORATORIES , It Detroit, Mich. Attach only Dept. 25, is full of action, excitement, 713 Townsend St., adventure and hero- worship. Have been using your Elimina- $1.00 tor for almost a year and it is Chicago, 111. But never does the author forget the im- to fi-ils agss Gentlemen: Attached Cod portance of science giving fine service. $1.00. in his tale, and there G. D. Murray. Roanoke, Ya. coupon Kindly send at once Townsend B" Socket is hardly any limit which scientists, bent on Power Unit, C.O.D.S $5.85, plus postage. Your Eliminator has given ex- on guaranteed 10-day Free Trial. on revenge, might not reach. cellent and satisfactory results. Also increased volume and im- proved tone. Name E. J. Luken, Louisville, Ky. The Roger. Bacon Formula, by Irvin Lester I have used yourEliminator fer Address I and Fletcher Pratt. Roger Bacon, an emi- a year and am very well satis- 1 nent scientist of the 13t1í Century, ex- fied with it and have recom- Clty State I pounded theories so far in advance mended it to many In this city. of n,.nald J. Scott, Lansing. Mich. m me ti ta mom mow im mi ta a his time, that he was accused of working ' u with black magic. This is an unusual interplanetarian story that will be en- joyed even by those who are not inter - planetarian story farts."
The Sixth Glacier, by Marius. (Part I.) GENUINE . According to geologists, the earth has NRegular been visited by five glacial periods in SET BUILDERS the dim past. If there were glacial periods Famous Type C in the past, why not in the future? HEADPHONES CetthisIiok We offer several thousand genuine Nathaniel Baldwin PERFECT Barawlk, the first and oldest radio type C headphones fresh from the house, Cauphul, the City Under the Sea, by factory in original sealed cartons at a fraction of their specialty offers you unusual George Cookman Watson. This cost. Nover before sold for lesa than $9. Price while they service this year. Bigger stocks, story is last only $5.50. Satisfaction guaranteed quicker shipments, lower prices. written by a newspaper man, who has or money refunded. Deal with an old established, reliable taken the trouble to get his information house. Get honest goods, honest service, front authentic sources. That he also BALDWIN HEADPHONES honest prices. Barawlk service makes you draws on his imagination, only enhances OUR hold all long distance records. you simply more money. Send now for big new Catalogahow- the interest. cannot get distance stations by any other ing lowest wholesale prices. PRICE means. An operator at San Francisco picked up a rode message from Bagdad. Turkey- BARAWIK CO: CHICAGO,U 5 %t 50 half way around the globe. a world's record. Maif ThL, Coupon Now for Free Radio Guide And others. ate, Whether you are a professional operator. $5 set builder, or li. C.L. these are the head- phones need. ORDER you NOW PREMIER ELECTRIC CO. 150 Nassau St. New York Please say you saw it in RADIO NETT'5'
www.americanradiohistory.com 6 S Radio News for January, 1929
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www.americanradiohistory.com Radio News for January, 1929 689 Review of Recent Radio Literature Breakfast H. M. for By BAYER Java THE .RADIO MANUAL by George E. Sterling, edited by Robert S. Kruse. Pub- lished by D. Van Nostrand Company, Inc., New York City. 8 x 6 inches, 666 Price The Tbxill Box, pages; halftones and diagrams. $6.00. ^ ... Though the preface of this work introduces it °t; , as "a guide and text book to those who expect to oo enter the radio profession as engineer, inspector, p-, I/,oGo a`act`y`OS`6/°ty ._ r_d ,` Y commercial or amateur operator, a reading of oß'Sasòoco óa S7F in p á it',r this book proved that it should take its place $ c,t every radio experimenter's library -that of a text tajetaoa¿5e\` ect`aß\S \ jiú.rart4 of radio as it should be studied. 07, for the study nb5h aás°cb 1 hook from which ßai`? gstáca It is, indeed, a remarkable eyt cuo° GQ, ^ been omitted. As ' ó`4PÉot ót°ß,el rN°t\a ; nothing relating to radio has t in the it has been written for specified preface, `vOQ `at`naáp Cá t°ä50 4tis `V s,atKVSlus f. everyone connected with or interested in radio. ft Especially to the "old timer" and the transmitting c\ t c°S\atta\\Qa4Gfsttga, 0` n beaste vao. ba R°ai,n'',eg. should it appeal with its profuse diagrams k 1 , "ham" 1ltiae www.americanradiohistory.com 690 Radio News for January, 1929 3C offered by quoting a goodly share of the all -too- short text. Individual, Independent "The familiar form of straight resistance -coupled amplifier is known to everyone. It has two great Arcturus Has It! disadvantages which have militated against its Speaker Volume Control use. First, the large number of high voltage 'B' and 'C' batteries necessary; second, its instability." The Centra- "An amplifier which minimizes these difficulties A 7- Second lab Constant was recently designed in England. Extensive ex- perimentation was done to adapt this principle to Impedance the standard American vacuum tubes, with the Volume Con- result that two very stable amplifiers have been Detector trol is the developed which give an excellent gain on direct only unit voltages and audio- frequency voltages up to 10,000 IT'S the fastest- acting De- that allows a and 30,000 cycles per second, respectively, with number of good uniformity." tector in the world -the speakers op- And that, in short, is the key to the pamphlet's Arcturus #127. No other De- erated from contents. To quote any more, we fear, would mean the publication of the entire text in this tector on the market brings the same am- column. It is unfortunate, indeed, that with text of programs in so quickly, so plifier to be so interesting a nature so brief an exposition was clearly. controlled in- written for this type of amplification; which, doubt- dividually less, is the prince of audio -amplification systems Put Arcturus A-C Long Life without af- when properly designed and operated. every in- fecting the Two resistance -coupled amplifiers are described; Tubes in socket -for Constant other speak- the first describes a set-up employing the 201A -type creased, undistorted volume Input tube with power amplification in the third stage, Resistance. ers in the and tke other one using the screen -grid tube with -for better all- around recep- LIST PRICE circuit. It a 171A -type in the last stage. Sufficient construc- tion-to end frequent tube $3.00 is a dual te- tional data are offered for the experimenter who replacements! Ask for the sistance unit may desire to build these amplifiers. with one resistance shunting the blue Arcturus Tubes-#127- speaker for volume control and the #126- #071-#180. - Arcturus other resistance in series with the line. THE OUTLINE OF RADIO, by John V. Radio Company, 220 Elizabeth L. Hogan. Published Little, Brown Adjusting the knob varies both re- by Avenue, Newark, N. J. sistances so that while one short cir- and Company, Boston, Massachusetts. 71/4 cuits the speaker to control volume, x 81/4 inches; 267 pages, halftones and the other resistance is added to the diagrams. Price $2.00. Third edition. line, maintaining a constant imped- The name of the author should need no intro- ARCTURUSLIFE ance. Easy to install, smooth and ef- duction to radio fans; if by any chance there is A -C LONG TUBES ficient in operation. Send for inter- any forgetful one, it is suggested that he lift the esting booklet of picture and wiring lid of his radio receiver (if it is a commercial diagrams, "Voltage and Volume Con - model) and, the chances are, he will find inscribed TUBE trols -Their Use." on the patent notice, among other things, a line attesting the fact that certain features in said 5 SETS 94m receiver have been made possible by the inventive genius of one Mr. John V. L. Hogan -the author In beautiful walnut of the book in question. cabinets se Mr. Hogan could not have employed simpler lan- THE MOST 20 Keefe Avenue Milwaukee, WiS. guage had he tried; and yet he has written a ASTOUNDING OFFER book which, with all its simplicity, fulfills its Ever made in radio purpose -and that is to popularize the science of Tuned radio frequency radio transmission and reception for the uninitiated circuit by the simplest and most readable explanations. GUARANTEED for Tone Quality and Selectivity fri In his introduction the author accounts for his Never These are used sets and were taken In trade for A.C. work, in a manner which covers his motive in a sets. AINPIR?B- nutshell. If after trying out one of these sets, you do not find that Walch Dog Imagine," he says, "that you are spending the this is the most wonderful buy you ever saw in a radio Wears we cheerfully refund your money. of tjaar week -end at my home; that we have drawn our set, will We are also offering to dealers and set builders the fol- chairs before the fire; and that you have asked me, lowing accessories: Audio Transformers $0.75. Crosley Cone Out 'Just what is this radio, anyway? How did it Units $2.50. UX280 B Eliminator Tubes $1.75. 30 Henry happen? What makes it work ?' that, after Chokes $1.00. 2 Difd. Condenser Blocks $0.60. Sockets Your first cost -and $0.15. Rheostats $0.25. Potentiometers $0.35. Cables is the only cost. a long pull at my pipe, I've said, Well it's like $0.35. G10 -Dials $0.85. Radiola Loop Antennas $1.65. Then why not enjoy this . , Crosley or Atwater -Kent walnut panels, size 9 x 26 inches manentlythe bet. .- $0.85. Output transformers for Dynamic speakers $0.95. Panels 6 z 10th $0.35. Variocouplers $0.65. Kodel B °' ter tube performance Eliminators $3.90. Kodel A Eliminators $3.90. These and prolonged tube life eliminators require slight repairs. Electrical pick -ups $8.85. alone offered by PATENTS -LAW AND PRACTICE, by Deresnadyne walnut cabinets $6.95. Peanut Tubes ÚV199 Oscar A. Geier. Fourth Edition. Pub- and UX199, 75 cents earns. Send money order with order. Dept. H. 4240 Lincoln Ave. lished by Richards & Geier, New York CHAS.. NOODWIN CO. CHICAGO, ILL. RITE City. Cloth bound, 9 x 6 inches; 46 DEALERS IN BANKRUPT STOCKS pages; no illustrations. Office distribu- The "SELF ADJUST ING "Rheartat tion. DEPENDABLE " B" BATTERY POWER Keeps filament voltage constant despite "A" battery Simplifies wiring, panel design, tuba The author of this booklet has compiled just control,variations. tuning. Insist on AOfPERITE. those questions most often asked by those inter- Nothing else can possibly perform newel'. Unconditionally guaranteed. ested in obtaining patent papers, and has per- formed the task of writing a study of a legal sub- Price $1.10 with Mount. so it makes ing, (M U. S. A.) FREE ject that interesting reading for the For sale by nil dealers. Book" layman. The following heads are covered: The "Amperite Law; Nature of a United States Patent; of latest circuits and Who May RADIALL CO. construction data. Obtain a Patent; What May be Patented; Appli- 50FranklinSt.,N.Y. RN -1 cation for Patent; Claims; Attorneys; Reissues; Write Department Appeals; Infringements; Disclaimers; Infringe- ment Suits; Injunctions; Validity and Infringe- ment Searches; Interfering Patents; Shop Rights; Employer and Employee; Design Patents; Trade Marks; Copyrights; Foreign Laws, including 100 Volt Edison Element. Patent Non -Destructive. Rechargeable "B" Battery with a schedule of charges for obtaining a patent in any charger. Shipped dry, with solution. $12. 140 Volt foreign country. The information in this booklet with charger, $17. 180 Volt Power Unit, with Trickle Charger, $24.00. One good radio idea may be worth may be accepted as authoritative, considering the SEND NO MONEY -PAY EXPRESSMAN millions. Barawik has thousands of ideas fact that the publishers for Free money. are patent attorneys of Write our Literature for radio set builders to make more SEE JAY BATTERY 915 Brook Ave., New York Barawik's Big Radio Book will help you many years' standing. CO., while elections are on and big national events stir the world. Send for your copy today - NOW. YOU CAN'T FOOL US, MISTER The new and flickering art of television is still BARAWIK CO. IC`AOO U.as'A.- suspect by many people are of DEALERS and Free Copy -who the same Mail This Coupon Now! For opinion as the farmer who looked at the camel and SETBUILDERS Complete stack of nationally known pari Name declared positively "There ain't no such animal!" and accessorie. Send for illustrated -Among them, no doubt, the radio editor of the catalog and discount 1921 Address San Francisco Chronicle who declares, as of Oct. . -Radio Exclusively Since 14, that in the Cooley system the slight lag of the CLARK & TIISON, INC. corona did not mar DECEPTION to YORK any I AMBERS STRFFT NEW great extent. " -Herbert F. Ross. The Gutolally Kama" House Please say you saw it in RADIO ArEif7S www.americanradiohistory.com Radio News for January, 1929 691 The Constructor's Page (Cnnl,uucd from page 660) gold, makes an attractive and rigid set. It works I have Model though New wonderfully on the broadcast band, Admiralty not bad time to test thoroughly on the short wave. In conclusion, I may say, it was only your blue- prints (No. 52) which pulled me through. They gave me the foe points of the game; I stuck close NORDEN -HAUCK to them and everything is as it should be. Had I been able to afford it, I should have used better variable condensers; but evidently the circuit won on its merits. Allow nie to thank you. SHIELDED SUPER-10 W. J. KEMPSON, 49 Dorothy Avenue, Ville Emard, Montreal, Quebec, Canada. Composite View o f Admiralty Shielded- Super - 10 showing im- A LONG JOB portant details of Editor, RADIO NEWS: design and con- It is almost an impossibility to express in snare ' - - -- sÁ snuction. words my grateful appreciation of the noble way in which I have been assisted, through the medium of RADIO NEWS. I am ever grateful to you and the hundreds (I have received 153 letters to date) who have answered my appeal in the October issue. I am endeavoring to answer each and every individual letter, but it takes time. JACK N. PETERSON, El Salvador, Central America. IINTIINED AERIAL COUPLERS Editor, RADIO NEWS: I have been a reader for the past four years; before you changed your policy, I missed a copy of RADIO NEWS occasionally, but since then, not one. It is just what I think a radio magazine should be, and I do not believe a radio constructor This great new Receiver is far in advance of competition. It is a or experimenter can afford to be without it. I and up -to- have several of your blueprints, which I consider powerful 10 -tube model incorporating the most complete alone worth more than the price of your magazine. date principles. Using the new screen grid tubes in the R. F. amplifier I would appreciate it if you will publish in the near future detailed instructions for making and push-pull audio system, make this new model the outstanding a choke to be used as an untuned antenna coupler in the grid circuit of a 222 -type tube. development in Receiver design for years. (For the broadcast band, a choke with around 80 or 85 millihenries inductance is suitable. A satisfactory choke can be made by winding 300 Features turns of No. 32 D.C.C. wire on a wooden or fiber 10 tubes used. Five 222 screen grid Indicating Meters on Panel. spool, 4 -inch in diameter. For short -wave work, 200A two with between 100 and 150 turns will be R. F. amplifiers, detector, Removable R. F. Transformers for all a coil 240 Hi -Mu's and two 210 tubes in sufficient. The choke should be "jumble- wound. "- wave lengths up to 25,000 meters. EDITOR.) the power audio amplifier. Electric or Battery operated. I would like very much to know what kind of Extremely sensitive-long range. two set Mr, Aikman of Salem, Ill., is using for coast - Simple to operate -only major to -coast reception without aerial or ground. I am Totally shielded. tuning controls. using a set of Browning -Drake variety, with a Super -selective-10 Kc. separation. A laboratory precision Instrument built 180 -volt "R" unit and I can receive WLW, WSAI, Perfect quality of reproduction. according to U. S. Navy Standards. WLS, WMAQ without aerial or ground. But, to get KFI, I have to have about 100 feet of aerial and a good ground. I would like to hear Complete attractive illustrated literature sent upon request. Full from experimenters who have tried methods of data $2.00 Postpaid. untuned aerial coupling for broadcast receivers. size genuine Blue Prints and constructional REX BRUMBACII, 812 Ruddle Ave., Anderson, Indiana. Write, telegraph or cable today. QIIITE SATISFACTORY NORDEN- HAUCK, Inc., Engineers Editor, RADIO NEWS: I would like to express my appreciation of a Marine Bldg., Philadelphia, Pa. description of a cone speaker that appeared in the article on page 46 of the July, 1928, issue by L. C. the highest class in the world. Dilatush. I made up the cone and departed slightly Builders of radio apparatus from the procedure in the article; as I mounted the cone on thick cardboard and cut the center out. Cable-Norhauck I then made cross arms to which I screwed the unit; and the cardboard, which had the cone cemented to it, was then attached to the cross - arms. What an eye- opener! I was dumbfounded with the results, and a gathering of my musical and radio friends unanimously pronounced my 1SAVES YOUR SPEAKER speaker perfect. It was tested against several manufactured speakers, and everyone gave mine THE CRAFTSMAN DOLLAR SPEAKER FILTER the belt. I have since made eight to order; hence $ is Guaranteed to relieve your Speaker of the plate my appreciation. D.C. (ISO to 250 volts). It reduces overloading, giving Speaker a chance J. J. C. SHARP, to operate at its best. Can be used as a headphone coupling. Com- 3 Search St., Caulfield, Victoria, Australia. plete protection, $1.00 prepaid. Invest NOW and prevent Speaker trouble and expense. CRAFTSMAN RADIO PRODUCTS, 351 Halsey St., NEWARK, N. J. QIIITE INCORRIGIBLE Improve reception with our Solid Resistors, 30c each. Editor, RADIO NEWS: 'rhe articles "A Britisher Chats on Radio" are, as a rule, to the point and have, as some of us Kinds- say, "a kick" in them. So much so that, at times, GEARS -AI Sayan I am inclined to think he is an American, as I The most accurate made and prices have never known a Britisher to be so "snappy." Open reasonable. We carry a complete r of for immediate I like his humor. ßS line gears in stock Let him write some more; CTRICITY shipment. Can also quote on special E. LINDERGREN, EL gears of all kinds. Send us your 2362 New York City. N days fits you for big pay inquiries. Ryer Ave., ELECTRICAL job at $50 to $200 Write for Catalog 40 (In spite of all temptations to belong to other a meek. All practical work on real equipment. MONEY- Chicago Stock Gear Works Blake remains an Englishman. RACK GUARANTEE. Free Radio Course. WRITE for nations, Mr. 00 -peso FREE BOOK, and remarkable tuition offer. 105 So. Jefferson St., Chicago EDITOR.) Maweeny Electrical School, Dept. 76 -AW, Cleveland. 0. Please say you saw it in RADIO NEWS www.americanradiohistory.com 692 Radio News for January, 1929 WILBUR C.WIIITEHEAD'S Izezo"pjcture 11fetho 4!ìeuches h-tri°D3) Drawing for partners. easilyquickly. frild2COLORSva°s WILBUR C. WHITEHEAD, the world re- nowned bridge expert, has written this interest- ing instruction course for you. BRIDGE by Whitehead is unique in that it teaches the entire game of bridge by a new and original form of illustration known as Whitehead's "PICTURE METHOD." Every hand is illustrated, each card in its proper color, red or black as the case may be. Thus the beginner, or even the most An example of the way in which each seasoned player, has an actual illustration of the hand is illustrated. manner in which the play is made always be- fore him. Whitehead, whose reputation as the foremost authority, national or international, on the game of bridge, is one whose advice cannot be taken lightly; he knows the game as few others know it. In this book he passes on to his readers, in an easily understandable fashion, his picture method-that made him a success. Get your copy of BRIDGE by Whitehead today -100 pages -9" x 12" size. Beautiful colored cover. Each point illustrated. 9e `/6 50c THE COPY At All Newsstands or write direct EXPERIMENTER PUBLISHING CO. 230 Fifth Ave., New York, N. Y. _MAIL THIS COUPON OW EXPERIMENTER PUBLISHING CO. ,' 230 Fifth Avenue New York, N. Y. Gentlemen: Enclosed find 50c, for which please send me a copy of BRIDGE by Whitehead. Name Illustration Address of how the play City State is made. Please say you saw it in RADIO NEWS www.americanradiohistory.com r-- Radio News for January, 1929 693 I Want to Know (Contimtcd from pape 662) (Q.) "I have an Atwater Kent "Model 20 Com- In Response To Popular Demand pact" set. Will you print in your next issue of Remo NEWS, a wiring diagram of this set with "C" battery connections? At times it plays; but it goes off with a roar every once in a while." (A.) You will find the diagram of this set in Fig. Q.2322 (on page. 662). By referring to the CHARLES R. LEUTZ diagram, you will see that the set contains two stages of tuned -radio -frequency amplification, a detector and two stages of audio frequency. Trans- former coupling is used in the audio -frequency am- announces plifier and grid resistors are used for stabilizing the radio -frequency amplifier. The set is equipped with a cable for the battery connections, and the colors of the various wires are indicated on the diagram. Two filament resistors are used; one controls the radio -frequency tubes and the other, the audio tubes and the detector. Probably the trouble with your set is due to a loose connection or to a defective tube. First go over the wiring carefully, and bend up the prongs in the tube sockets. Then test the trans- formers and the fixed condensers with a battery and a pair of phones. When the phones are connected across the windings of the transformers, a distinct click will be heard, if the windings are good. The small fixed condensers will not give a very noticeable click if they are in good condition; while the filter condenser will give a click but no continuous noises. If all of the connections, appear to be good and the parts test satisfactorily, the A NEW BROADCAST RECEIVER tubes and batteries should be tested and finally the aerial and ground should be checked. LEUTZ Broadcast Receivers are known all over as the "Highest Grade Radio Receivers in the World." In proportion to their price, there is more money spent on material and labor than in any competitive make, this means BUILDING A RESISTANCE AMPLIFIER you get QUALITY. (2323) Mr. D. W. Brown, Niagara Falls, N. Y., The LEUTZ organization has always led the field in new and original writes: features in their designs. Many of this year's sales points in competitive (Q.) "I am going to build a resistance -coupled makes, are features which were original with Leutz two and three years ago. amplifier for my tuned- radio -frequency receiver. I In a Leutz receiver, you obtain an instrument scientifically correct, the best want to use the amplifier also for receiving tele- that engineering skill can produce. vision signals with the unit described in the Novem- The present two models, the Universal Transoceanic "PHANTOM" and ber issue of RADIO News. I am afraid that I will have trouble with motorboating when trying "SILVER GHOST" are continued as before, for the clientele that insist on the to use the amplifier with a 'B' power unit, and best with no limitations of size, simplicity or cost. I am writing to find how I may make the amplifier In response to the many inquiries for a popular priced broadcast receiver, so that I will not have any trouble from this simple to operate and scientifically designed to give superior performance, score. By using choke coils in the correct com- LEUTZ offers a new CONTROL CONSOLE. The result is not by I believe an SINGLE bination with -pass condensers, in many amplifier could be constructed with no tendency to just another console, but an instrument original details. The won- motorboat." derfully efficient Screened Grid Tubes are used in the radio frequency ampli- "I would also like to get some information for fier. A very powerful Push -Pull power audio amplifier is provided to constructing a resistance -coupled amplifier using a operate an improved type of Dynamic Speaker which is built in the console. screen -grid tube in the first stage and a power All electric operation is obtained at a very economical figure. The console tube in the second stage. If this can be done, itself is a fine example of woodworkers' craftsmanship. will you supply any information possible for the construction of one ?" The design and construction throughout is to the typical Leutz high (A) "Motorboating" in an amplifier is simply standards, the performance sets new ideals. a condition of oscillation brought about by the We will be very glad to send you the new literature on this new con- feeding back of energy from the output circuit of sole, you will find it very interesting, write now. an amplifier to the input. The feed-back currents usually occur through "B" power units or run- down "B" batteries. In the older types of audio transformers, where the bass -note response was poor, these feed -backs were usually in the form C. R. LEUTZ INC. of high -pitched whistles. In the newer trans- formers and in the impedance- and resistance - 195 PARK PLACE LONG ISLAND CITY, N. Y. coupled systems, the feed -back usually appears in the form of low humming noises or the well -known Cables "EXPERINFO" N. Y. "putt, putt" of motorboating, which is really only a very slow oscillation. In a regular three -stage amplifier using any of the common types of coupling, it will be found that the signal -current or A.C. component (this should not be confused with the direct current in the plate circuits, which is read with a D.C. meter.) SEND FOR NEW RADIO will be in phase or traveling in the same direction, BOOK- IT'S FREE! in the detector plate circuit and the plate circuit of New hook -ups. This book shows how to make the second A.F. stage at a given instant. The HE Shanco Battery Clip design assures free short-wave receivers and short-wave adapters. current in the first and third stages will be out 1 and uninterrupted flow of electrical current. How to use the new screen grid tube in D. C. of phase with the former, or traveling in an opposite No springs totheat up, burn or drop out. Made of and A. C. circuits. How to build power ampli- moment. The direction of powerful tension, tempered spring steel solidly fiers, ABC eliminators. Up- to- the -minute direction at the same before the currents in these circuits is not important if riveted together. All parts electroplated information on all new radio developments. assembly (not galvanized or tinned), acid- resist - It's free. Send for copy today. new batteries are used because of their relatively ing. Jaws open wide and are easily applied. The low impedance; but, if the impedance of the bat- Grtptite bulldog teeth "stay put" and bite right KARAS ELECTRIC COMPANY teries or power unit is relatively high, two effects through corroded bars and terminals. Clip cannot 4038A2 -North Rockwell St., Chicago, Ill. are possible. The first and second A.F. currents fall over and "short" your battery. are opposing, giving a slight reduction in the signal Write Dept. 74 for free literature and prices. Name is strength; but, what more important, the detector CO. and second stages are in phase, which will cause SHANKLIN MANUFACTURING ¡-- St. and No Dept. 74, Springfield, Illinoist "^ regeneration. City and State Both effects are due to the impedance of the 4038 A2 "B" supply being common to all the plate circuits. The regenerative effect to the second stage from the detector will increase as the impedance of the "B" supply increases, and also as the signal Insure your copy reaching you each month. Subscribe to Radio News -$2.50 a year. strength increases; and, if the combination of the Experimenter Publishing Co., 230 Fifth Avenue, N. Y. C. two is large enough, the regeneration of tb^ system Please sap vatr saw it in RADIO NE Ti' S www.americanradiohistory.com 1 694 Radio News for January, 1929 may overcome the resistance of the circuits and the amplifier will oscillate. The logical way to prevent these oscillations is to separate the plate circuits of the amplifier tubes, TUBE and the easiest way to do this is to insert audio - [ frequency choke coils and by -pass condensers in each of the circuits to prevent any feeding back of these currents. DIO iI//Pa.tr móunted Constructing the Amplifier n r i In Fig. Q.2323A you will find the schematic diagram of an amplifier with resistance coupling, COAST incorporating the chokes and condensers recom- !COAST mended in the discussion above. Two other A.F. RECEP- chokes are inserted in the circuit, one in the grid TION circuit of the last audio tube and the other in the Superphonie 7 lsa world beater! An exceptionally high plate circuit of the detector. Both of these chokes grade receiver that is amazing the Radio World. Latest 7 tube tuned radiofrequency circuit, using 4 radiofrequency will help to stabilize the amplifier and also in amplifiers. detector and 2 stages of audio. Power tube can be preventing motorboating. The first two tubes in used t last audio stage. Extremely selective marvelous sen- sitivit Single drum dial control. Straight line wave length the amplifier are high -mu tubes of the 240 type. condensers permit accurate, equally spaced tuning over en - The finest re- The last is a power tube of the 171 or 210 types. tire wave band. AU sockets spring cushioned to eliminate are microphonlc noises. Bakelite subpanel 18 S5 deep) insures The values of the grid and plate resistors minimum dielectric losses. Clear and realistic reception guar- ceiver can be im- indicated on the diagram. The audio -frequency anteed. An exceptionally beautiful walnut finish, metal front first and second am- panel 7' x 18'. Complete chassis. No extra parts to buy. All chokes in the detector plate, arts mounted ready to wire. No special tools needed. All proved with plifier plate, and third grid circuits, may be the hook -up wire and colored battery cable included. Value secondaries of audio -frequency transformers or they $60.00; our price $t6.95. Televocal Qual- may be obtained for the purpose. The choke in TESTED AND APPROVED the plate of the power tube should be suitable for Severe laboratory tests haveprovedthe remarkable efficiency ity Tubes. All of this set. Owners everywhere are sending us letters prais- the plate current of this tube. The coupling con- ing its wonderful receptive qualities. densers have a capacity of .006 -mf. A .001 -mf. SIMPLE WIRING DIRECTIONS standard types. fixed condenser is shown across the first impedance Very easy to wire this set with the instruction we furnish. Just connect a few wires. All you have to do is to follow unit, but is not necessary if the detector in the numbers. Simple as adding 2 and 2. Ask for them at set is already provided with a condenser in the Can be wired in a few minutes by anyone. plate circuit. No radio knowledge needed. Make money your dealers. by wiring, these sets in your spare time and selling them to your friends. Screen -Grid Amplifier (A2.) The 222 -type screen -grid tube may be Televocal Corporation -coupled audio- frequency am- Just write your name d address on post card and ask us to send used in a resistance you this wonderful outfit. We ship right away. Upon arrival Pay n ly plifier if a lower screen -grid voltage than usual sand Televocal Building 519.50 with order.IWeepay shipping charges./ is used. When it is used in this way a voltage Dept. A -6 amplification of about 35 per stage can be obtained RADIO EQUIPMENT CO. 12 -A CHICAGO, ILL. 588 -12th Street and, with the proper coupling condenser, a flat 549 S. Wells St., Dept. frequency -characteristic from 50 cycles, or lower West New York, N. J. up to 10,000 cycles can be realized. Fig. Q.2323B shows the connections of such an amplifier; the input is coupled to the 222 tube through an audio -frequency transformer or a Come to resistance coupler. The first tube is coupled to the second through condenser Cl, which has a capacity of .006- to .02 -mf.; while the output of the power eiev ca tube \'2 is coupled to the speaker through the Washington Quality Tubes usual condenser and output choke. The filaments The educational advantages of a visit to the of Te tubes are equipped with ballasts, R2 and Capital of our Nation are of inestimable value R3. The screen -grid tube Vl also uses the usual Stop at tapped resistor to reduce the voltage and obtain the correct bias for the control grid. The voltage on the screen grid should be about The LEE HOUSE 22 volts, which is lower than the usual value (45 15th and L Streets, N.W. be between 135 SY volts). The plate voltage may Three squares to the White House. A new GET and 180 volts and if a 171 -type tube is used in and modern Hotel. Refined environment. the last stage the same tap may be used for to 250 ROOMS - 250 BATHS both tubes. The binding post P is connected Rates: IDIBCv000W: KiT the plate of the detector tube in the set, and the usual manner; that Single room 5 3.50 daily Before =agicalle batteries are connected in the Double room 5.00 pMñ is, if the "A+" and "B -" are connected in the Single room (with meals) 6.00 d Pow set, these connections should also be used for the 2 persons (with meals) 10.00 " Absolutely amplifier. ROBERT BLOCK, President sileuC ee esitASe and T ele-e e- adaptable ionTOEt1tE On the Short Waves vivisionóterodY In tec 1N (Continued from page 665) cour als- they come on the air at about midnight G.M.T. Custom Set Builders 10 NEW they should be useful to American "fans." Being Browning -Drake has an interesting 8 very regular, Write saving pdetails experimental, they are, of course, not and unusual proposition. Take y a[ d. Addressddrüand pees. but I believe that Tuesday and Thursday mornings advantage of the fact that more count (i.e., Monday and Wednesday evenings in America) Browning- Drakes are built than any P1oe p. which to catch them. They are DAVID G°..1 ' are the times at app =tIi how transmissions come other. P. R. anxious to know their p,d )ion of Ave.. N.Y.C. through and give announcements in English, Dan- Write today 350 Madison ish, French, German and Dutch. 417, BROWNING -DRAKE CORP. Worn I notice in the October issue of RADIO NEWS that reference is made to the practice adopted by CAMBRIDGE, MASS. 5SW (Chelmsford, Essex, England) when closing down. The 12 "strokes of the gong" referred to are of course the chimes from Big Ben, the well - known clock on the House of Parliament at West- minster Bridge, London, tolling out midnight. RESI-1 MA the procedure Barawik offers set builders bigger As a matter of general interest, YOURULTIMATE RADIO bargains - bigger opportunities to make for 5SW appears to be to relay the London pro- F N kit money this season. New sets, new gram from the regular medium -wave station 2L0 ideas. all the leading parts, dynamic speakers, rock- until midnight on those nights when it closes down AT ALL bottom riceBspl ggre stocks, quicker at that hour, which are, or at any rate, were service Send or Big Bargain Book today -free. 21D Canal Sta. recently, Tuesdays, Thursdays and Saturdays. 2L0 AUTHORIZED BARAWIK CO as CHICAGO, U. S. A. signs off at midnight by superimposing the chimes from Big Ben on the dance music which is taken DEALERS Copy Mail This Coupon Now For Free after 10:30 to 11 p.m. from one of London's Name fashionable clubs or hotels, and the "Goodnight" is said actually before switching over. The an- Your Own nouncement heard at midnight is given by 5SW PrintCards, Stationery Circulars, Paper, etc. Save At 12:30 a.m. 5SW can often be heard money. Print for others. big profit. Complete itself. outfits $8.85. Job press $11. $29, Rotary $149. All giving a recital of gramophone records, which essay. lasts until 2 a. m.; i. e., from 7:30 to 9:00 THE KELSEY CO., p.72,, Meriden, Conne Please. say you saw it In RADIO NEWS www.americanradiohistory.com Radio News for January, 1929 695 p.m, E.S.T. Its wavelength is 24 meters and its power 20 kilowatts. It does not transmit on Satur- days and Sundays. Reception here is usually pretty good, about R4 or R5 on two tubes. here in Aruba, which, I might mention that Come - incidentally is a small coral island in the Caribbean 2,000 miles from New York, I get regular reception from KDKA, W2XAF and \V2XAD, and last Out of the Maze but not least, W2XAL, the RADIO NEWS station. The first three are particularly good; being at times of sufficient strength to be audible on the in Building loud speaker on even two tubes. Bearing in mind the fact that W2XAL only uses 1 /100th the power Power Units of the other stations mentioned, it comes through wonderfully well; but unfortunately is usually accompanied by a background of two or three spark cts, and a heterodyne whistle possibly from \V2XAF. the excellent programmes sent The value of , rt;;d ° - out by these short -wave stations to somewhat re- t!.° mote tropical spots like this cannot be over -esti- ` mated; and, although I have no wish to criticise A, a service which is the only reward we get for TRUVOLT DlViOER straining our cars and tubes night after night, news items are, unfortunately, rather scarce. KDKA transmits news items regularly at about 4:30 p.m. E.S.T. (5:15 p.m. here) at present on 25.4 meters; but surely these must be read to an almost absent audience, and would be of much greater service if given with one of the later baseball announcements or when signing off. Now and again news is heard in the evening, but WGY apparently has no regular service at all and, if KDKA goes over now to 4:30 p.m. E.S.T. TRUVOLT DIVIDER that will be our lot. A news service after the Icee. 1 :. S. rat. Off. style of that given by the English stations could not fail to be extremely appreciated by the thous- ands of listeners whom these short -wave stations must have between 40° and 120° W. of Greenwich, A Universal Voltage Separator and particularly in the tropical belt where anything With the New Electrad Truvolt Di- unit. Five potentiometer type con- above 60 meters is spoiled by static. News given knobs at 8:00 p.m. E.S.T., for instance, would be avail- vider, you can easily build a better trol show values on a scale you can buy, in much of high visibility. Can be mounted able on the Pacific Coast between 5 and 6, here eliminator than at about 8:45 and at Pernambuco at about 10:30; less time than you could construct on baseboard or sub- panel, or used North American Continent, the unit using many separate un- as the front panel on a PRICE which would cover the related resistances. metal cabinet, at the same and the \Vest Indian and South American tropical time providing posts belt at times convenient to everybody. binding 50 This device is a complete Truvolt for all B and C voltages. $12 As for curtailing the hours of transmission from wire -wound resistance, so arranged these stations, surely there is plenty of room for with adjustable contacts that proper Electrad specializes in a full line of adjustment amongst the other six hundred odd grid and plate voltages are delivered broadcasters without interfering with these pioneers Controls for all Radio Purposes, for operation of any receiver of pres- including Television. who are doing so much to break down the barrier ent or anticipated design. inaccessible regions and of silence between former Mail coupon for full information. the outside world, and whose call signs are by- By dividing the filtered voltage into words in radio everywhere. usable values, it eliminates all neces- I hope that you are able to find space for at sity of mathematical calculations in least a part of this communication, and that the constructing a power pack. It does stations referred to may be able to do something away with a great deal of wiring and INC. indicated; which, I am certain, ELECTRAD' in the direction the need of voltage regulator tubes. Dept. NA-1, N. Y. would still further add to their great popularity build a power New York, It makes it possible to Varick St., of particularly amongst those listeners to whom their supply device which is universal in 175 ?My me FREE conan- voices alone are able to penetrate. \Vhy not fill its application. send volt Divider list up one or the other of those frequent pauses for Please Truvoltyour mailing the Electradut me on "station announcements" which so seldom have The Truvolt Divider provides the ual and p, Data and information. any significance, with news items? important link which has heretofore for Circuit Anyhow, the best of luck to the American short- been missing in power plant con- wave stations, and particularly those referred to, struction. It takes all guesswork ...... and many thanks for the great service they are out of eliminator building-makes it Lame rendering to us here. possible for the non -technical fan to Ions THYDEN, build a high -grade power pack. Also Address . do Arend Petroleum Maetschappij, Aruba, any power plant can be built around it. State....- Dutch West Indies. Case made of genuine bakelite, it ...... will add a smart appearance to any City ...... PREFERS USE OF COIL FORMS Editor, RADIO NEws: My experience with short -wave radiophone recep- tion started about the month of April, 1926, when the only short -wave radiophone stations who could be consistently received were KDKA and WGY. To be perfectly frank, those two stations are the ELECT RAD only ones which I have been able to receive consistently since that time. However, it seems that other stations will be as easy to receive this winter as are those two. The other evening I received for the first time the new 2 -kw. short -wave station, CJRX. Their signals were not particularly strong, and their Build it wave is so near the 26 -meter wave of KDKA that KDKA spills over into CJRX's program. However, at my first session with CJRX I was Right able to hold them for about fifteen minutes around 5:30 p.m. This New Catalog of Barawik, the first and oldest radio From time to time I have listened to \VLW's specialty house, offers you unusual short -wave radiophone station and to others whose service this year. Bigger stocks, quicker shipments, lower prices. call letters I could not identify because of local Deal with an old established, reliable noise or inaudibility. These may have been short- YA home. Get honest goods, honest service, ^Y honest prices. Barawlk service makes wave radiophone stations, or harmonics of powerful you parts and accessories more money. Send now for big new Catalog show- stations in the broadcast wave bands. ing lowest wholesale prices. My first will help you. Yaxley products short -wave receiver employed low -loss are used in vital places in many of the most coils of the basket -weave type. Later these were BARAWIK CO. CHCAAGOU S' a. prominent and successful sets on the mar- Mail This Coupon Now for Free Radio Guide mounted on burnt-out -tube bases for convenience ket today. Send for the new catalog. in changing them in the receiver. These were entirely successful but wouldn't "stay put;" so I YAXLEY MFG. CO. started winding my short -wave coils directly on Dept. N-9 So. Clinton St., Chicago, Ill. the tube bases using smaller wire. These were Pleasc say you .row it in RADIO NEiVS www.americanradiohistory.com 696 Radio News for January, 1929 &1114D MECI1ÀICf-THE BOOK OF THE AGE The greatest book on modern aviation ever published. The many ramifications of the aeronautical field that it covers can be better appreciated by a glance at a synopsis of its contents. CONTENTS IN BRIEF: Theory and Fundamental Principles of Flight. Stability -How an Aeroplane Flies. Complete Design, Construction and Assembly. Scale Drawings -Names of Parts. Flying Instructions -How to Become a Flyer. Motors -Latest Inventions -Instruments, Use and Functioft. Radio Installations. Gliders. Airports and Lighting. Glossary of Aeronautical Terms. The Aeroplane Mechanic. Model Making. AERO MECHANICS, written by Augustus Post, is the most complete MR. AUGUSTUS POST treatise of its kind ever published. It deals with every phase of Editor of AERO MECHANICS aeronautical construction and operation, and its entire contents is passed upon by Mr. Post, who is one of the best known pioneers Mr. Augustus Post, editor of AERO ME- CHANICS, has been prominent in aeronautical of aviation. Learn all about this circles throughout the country for over ìwl twenty years, his experience and adventures great new field. Obtain your copy have made aviation history and placed him in of AERO MECHANICS today. Over EXPERIMENTER PUBLISHING CO., INC. a position to pass on to the readers of AERO 230 Fifth Ave., New York City, N. Y. MECHANICS honest, accurate and entirely 112 pages. Fully illustrated. dependable information on every phase of Large 9" x 12" Gentlemen: Aviation. Says the North American Re- size. Enclosed find 50c, for which please send view of Mr. Post: "No man in America me a copy of your remarkable new book, has been more continuously at the centre of AERO MECHANICS. aeronautic activities in this country, and in THE C COPY touch with more history -making airmen 5 O bere and abroad, than has Augustus Post At All Newsstands, or Write Direct who, besides having' the "history of the air" Name in his head, has personally participated in some of the most thrilling adventures of Experimenter Publishing Co., Inc. Address aviation." 230 Fifth Avenue, New York City City State Please say you saw it in RADIO NEWS www.americanradiohistory.com 697 Radio News for January, 1929 successful but not to be compared with the low -loss coils of basket -weave type. The coils I use at the COAST TO COAST present time for the 30-meter band are wound of With Tremendous Volume No. 16 D.C.C. wire on low -loss forms with a How Many Lives has a of diameter of 1h inches. The turns are slightly Is the Report of Every Builder separated (the width of ordinary string which holds the turns in place) and the whole is given a coating 8 -80 the turns TELEVISIIDN THE LINCOLN of Dupont's household cement to hold ONE SPOT SUPER rigidly and to exclude moisture. I note that many new short -wave radiophone TUBE? fans experience difficulty with body capacity. I did, too, until I learned to keep the rotor plates of my tuning condensers at ground potential or as near ground potential as possible. Also I have read in most of the radio magazines published (and I get most of them) that short -wave receivers would not work well on a "B" unit. I not only use a "B" unit but have done so for at least a year and a half and further I use a semi -power tube in the last stage of a two- (or three -) stage audio amplifier, lighting the tube filaments with alternating current. This of course is the usual practice now with receivers for the broadcast band 75 LOGGED but I doubt very much whether many experimenters STATIONS are doing this with short -wave receivers using head THRU CHICAGO LOCAL sets. The hum resulting from use of alternating report set builders in Chicago, the worst current on the filament of this last audio stage is inaudible; but an adjustable resistor States for DX reception. practically city in the United is necessary for both the center tap of the filament Here's the reason -note these exclusive fighting transformer and the grid -bias resistance. features: Furthermore a 226-type tube works better than a ONE SPOT- 10 KC SELECTIVITY 112 here, as far as hum is concerned, and gives WITH FULL POWER; nearly as much volume. A VT -1 works as well FOUR SCREEN GRID TUBES WITH as the 226 and better than the 112. Anyone who NEW INTERMEDIATE MANUALLY wants to use VT -1's as power tubes or for any TREMENDOUS AM- other purpose, should remember that the filament TUNED, GIVING voltage should not exceed four, and should be less PLIFICATION ; if long tube life is desired. REGENERATION ABSOLUTELY ELIM- I read of short-wave fans hearing the foreign INATED; stations but so far I have not heard them. Here's NO SQUEAL POSSIBLE; hoping! MARVELOUS TONE; CLINTON A. ANDERSON, List Price CLOUGH SYSTEM OF AUDIO. 215 Red Rock Bldg., Atlanta, Georgia. If you want performance you never knew S7.5o was possible, write us at once for full in- formation. THE S.W. SUPER Editor, RADIO NEWS: RK Lincoln Radio Corporation I have built several receiving sets, all from data Corner Wood and Ogden in RADIO NEws, from a one -tuber up to a nine - 3 CHICAGO, ILL. tube superbet and have so far had very good results i.4mp - Established 1923 - with them all. My latest is the short -wave super any Send 25c for booklet giving constructional data and described in the October issue. (I Want to Know, The name Raytheon on complete story of development of the Lincoln 8 -80. page 351); I used three intermediate stages instead type of tube assures a service - of two and left out the external oscillator; for I life so long that it is often have found that by advancing the potentiometer equivalent to the lives of two to allow the intermediates to oscillate, the C.W. or three ordinary tubes. sigs come in very well, with a slight decrease in of sturdiness volume, of course. My advice to all short -wave The principles Barawik offers Bet builders bigger fans who want a real loud- speaker set on foreign and strength developed in the bargains bigger opportunities to make production of Raytheon sound - money this- season. New sets, new kit stations is to spend a few bucks on a good 30 -kc. ideas, all the leading part., dynamic intermediate kit and build this super. reception tubes have been ap- speakers, supplies. etc. Lowest rock - My location is a poor one for reception, because manufacture of bottom prices. Bigger stocks, quicker plied to the ..vies. Send for BIS Bargain Beek today-Ira. the local powerhouse is almost in my back yard; Raytheon television tubes. 21B canal Sta. yet I bring in 5SW with very good volume on BARAWIK CO Il CHICAGO. U.S. A. The Raytheon Kino -Lamp is the speaker almost every night when conditions the long -life television receiv- Mail This Coupon NowI For Free Copy are fair. With the ordinary three -tube regenerative to all sys- Naine I can barely bear it with the phones. ing tube -adapted The set is very easy to tune; all done, practically, tems, and made in numerous with the antenna tuning dial once the set is oscil- types. Address lating. I think RADIO NEWS is a wonderful magazine for both the layman and service man; as well as for the amateur set builders who play with radio for the pure joy and satisfaction of making your own and having it work. I will say we cannot get along without it. The short -wave section is excel- lent and I hope it will grow. ITV!'" THOMAS MERCIER, 0 85 Sumner St., Fitchburg, Mass. LITTELFUSES HAVE I T THAT EXTREME QUICKNESS AN ELABORATE SHORT -WAVE ANTENNA of action necessary to protect radio and rectifier tubes. Mier circuits, galvanometers, mllllammeters, etc. (1" z Editor, RADIO NEWS: die.). Approved by leading radio laboratories. Mount as The following data may be of interest to builders shown or hang directly In the line by pushing on a pair of ORYP- CONNECTORS. of the "Junk -Box" receiver. I have made several Prices, postpaid (C.O.D. or cash unless rated): changes in construction which seem to make a great Littelfuses, 1/32, 1 /16, %. Y.. ys, 1. Ea. Doz. Per 100 2, 3 amp. $ .15 $1.50 $10.00 improvement. In place of the filament -ballast re- Mounting Blocks .20 2.00 15.00 sistors, I use one 30 -ohm rheostat for the two ORYP- Connectors -In pairs .15 1.50 10.00 (three) tubes. I cut out the switch, and inserted 4 Raytheon Littolfuse Laboratories, Dept. 4, 1772 Wilson Av.. Chicago the rheostat in the "A-." This seems to give me a much better control of regeneration. Foto.Cell I have added an extra stage of audio, and get -- SSW, PCJJ, PCLL, KDKA, W2XAF, and W2XE The long-life television sending tube. SET BUILDERS on the loud speaker nearly every night. in either hard -vacuum or gas-filled write for My aerial (which has been in use over five types, and in two sizes of each. years) consists of 29 feet of what was once stranded Information and Prices Discount Card bare copper wire, with a 25 -foot bell -wire lead -in; upon application Enabling you to purchase the new and 30 feet high at one end, 25 at the other. The Correspondence is invited from all Improved Knapp "A" Power Kit at big far end is grounded to a three -foot pipe set in interested in television discount -Write for full particulars. the ground, by 25 feet of No. 24 D.C.C. wire. DAVID W. KNAPP,Pres. For a ground I use several water pipes, five CO. or six two -foot pipes driven deep into the soil, RAYTHEON MFG Knapp Electric, Inc. and a vertical counterpoise consisting of about of I'. CAMBRIDGE MASS Division R. Mallory & Co. Inc. 30 feet of No. 16 D.C.C. wire. Room 417, 350 Madison Ave., N. Y. C. I wound a smaller coil on a 199 base, and suc- Please say you saw it in RADIO NE WS www.americanradiohistory.com 698 Radio News for January, 1929 ceeded in getting PCLL, and a station I am pretty oCTINIEle sure was ANH, Malabar, Java, as well as numer- ous commercial code stations. Some of the ham received on this set is; ea, eb, ec, ed, ee, ef, eg, ei, ek, em, en, ep, oh, fm, fq, aj, na, all ne districts, nj, 'nm, nn, np, Write nq, nr, all nu districts, nz; also KHAH, the monoplane "Greater Rockford." for I would like to hear from fellows of 15 to 18 in this country or foreign, who are interested in this rp.EVEA1F ham radio, short waves, or "Junk -Box" con- struction. Discount THOMAS L. SIGLIN, JR., WICPH, Card 23 Norwich Ave., Providence, R. I. NOW! BATTLESHIP STYLE It will enable you to purchase the Editor, RADIO NEWS: New and Improved For the past two months I have been using the RADIO NEWS short-wave receiver (blueprint No. KNAPP "A" POWER KIT 52) with splendid results, using only the detector at a liberal discount and two stages of audio (General Radio 1:5 and The new Knapp "A" is the finest and most com- 1:3) Using a steel panel one quarter -inch in thick- plete kit ever offered. It is the only "A" Power ness, no body capacity is noticeable. Foreign sta- adaptable to Short Wave -Super Heterodyne tions received regularly are 5SW, CJRX, 2ME and Television reception. and PCJJ. Take advantage of the wonderful offer today - R. IL ADDISON, write 28 Amandine St., Dorchester Center, David W. Knapp, Pres. Boston 24, Mass. (Our correspondent in for Knapp Electric, Inc. goes substantial con- Division of P. R. Mallory & Co., Inc. struction; as a matter of fact, a very thin sheet of metal forms a practically perfect shield against Room 417, 350 Madison Ave., N. Y. C. capacity, though not against a strong magnetic field.- EDtrou.) With the same creative enthusiasm Complete Parts for that produced the first radio vacuum AN ELABORATE COMBINATION tube (1906) Dr. DeForest has now Some time ago I was flooded with requests from New TYRMAN developed the perfected Audion. other readers, for particulars of my short -wave set. IMPERIAL "80" When you replace your Unfortunately, circumstances did not allow me the tubes with Complete A-C Socket Power Operation. DeForest Audions you will exper- time to answer, and in the meantime I have developed a set that will be of great interest Uses A -C Shielded Grid and A -C ience a new enjoyment in clarified to Heater Type tubes. Fully described reception. the advanced amateur and, more especially, the in our free catalog. owner of a superheterodyne. With this I listen Send today for your free copy of regularly to Chelmsford and the Dutch, French 1929 Catalog -FREE the interesting booklet by the and German short-wave broadcast stations. Includes description and complete parts "Father of Radio." The long -wave side is exceedingly efficient, and for H. F. L. Isotone, Madison -Moore one wonders why some sets cannot bring in stations "A C," New Thordarson Power clearly on the lower end of the broadcast band; Amplifier, World's finest Dynamic as when tuning with this set we get a great Speaker. Deforest Radio Co. number of stations below WPG, and distance well Discounts for Set Builders around 11 p. m. Pacific Coast reception is quite JERSEY CITY N.J. frequent. CHI -RAD The combination comprises (a) a short -wave CHICAGO RADIO single- circuit regenerative unit with plug-in coils; APPARATUS CO. (b) a one -dial R.F. amplifier and detector unit; 415 S. Dearborn St., Dept. RN '44 (c) an oscillator unit; (d) two I.F. stages with CHICAGO filter; (e) an A.F. amplifier, one stage transformer - coupled, two stages resistance -coupled, and an out- Improved socket 210 antenna plug -cor - put stage of two tubes in push -pull with 300 rectly built. New volts on the plates. typebrass -plate and Now, there are two controls for the long -wave mica blocking con- denser. 10 -ft. con- set, one for the short-wave set, and a D.P.D.T. Barawik offers set builders bigger necting cord. Neat Yaxley jack switch. The oscillator condenser for bargains - bigger opportunities to make ,Compact. Safe. short -wave work money this season. New sets, new kit Work s anywhere. becomes the oscillator condenser ideas, all the leading parts, dynamic And only $1.501 for the long -wave super by throwing the switch. speakers, supplies, etc. Lowest rock - bottom prices. Bigger stocks, quicker There is one combination rheostat and potentio- service. Send for Big Sassais Boot today -fr.a. meter, and one master battery control. I used a former Freed -Eiseman panel. BARAVVII CO., CHICAGO, U.S.S.A. This set, with its interchangeable coils, will tune ñaail This Coupon Nowl For Free Copy from 17 to 24,000 meters; it is a real DX getter, is very selective and gives assembly -hall Name volume. What I consider very important is that For DX Results the 23- control set, with its battery troubles, has Address been reduced to not more than three controls at You must have maximum signal one time and operated from the house -current supply. pick -up. Don't depend on skimpy When changing from one waveband to another, antenna. Don't be discouraged by the filaments of the side which is not in use are "dead spots." Just use a Clarostat automatically cut out. Antenna Plug, alone, or as a "boos- On account of the great distance from broad- ter." You'll be surprised! cast stations here in the Far North (120 miles north is /3ook of Quebec) shielding was not necessary; but it Also, use proper grid leak value - was provided to see what the difference would be. 3ingsûealers from 2 megohms or less for "locals," A slight gain in selectivity was observed, and when to 10 megohms for DX. The GRID it was operated with the battery in a shielded GGER PROFI TS LEAK CLAROSTAT provides pre- container and cabled underground antenna, static cise values at was reduced to practically nil. all times. For my intermediate and R.F., I used "peanut" Matchless bargains in radios and accessories. Full line of Sleeper Browning Dtake,Carter, Utah. And be sure you have correct "B" tubes to save space. The R.F. coils are placed Kodel, G.E. Tunear. Burgess, Jewell, Belden, Cunningham tubes, and "C" voltages. Several types of under the three -gang variable condenser and the nationally advertised vans. storage batteries. chargers. etc. Big peanut tubes between the different sections; so that opportunity for live ones who can sell radio. Double sales quick. Clarostat will attend to that. Use your letterhead. Exclusive territories open. Act -NOWT the two sets, one with nine tubes available for NEW ENGLAND MILLS COMPANY literature describing com- short waves, the other with twelve for long waves, Distributors of :Nationally Adrertfsed Radio Lines Writeforplete line of Clarostets and are contained in a cabinet 7x9x30, and are so Dept. R200 551 -55 Washington Blvd. Chicago, 111. how to improve your radio results. Or ask your dealer about Clarostat radio helps. simple to control that a child can operate them. The short -wave super has been designed for CLAROSTAT broadcast reception only, and is a combination of MFG. CO., INC. the sets described in RADIO NEWS for July, 1927, DEALERS and Specialists in Variable Resistors and October, 1927 and the short -wave superhetero- SETBUILDERS 281 North St. dyne described in the February, 1927 issue of the Complete .rock of nationally k n part. Sixth same magazine, where all data as to coils, etc., and cen:orim. SenJ for illu>mted R.M A analog and discount ,hen. Brooklyn, N.Y. can be found. have eliminated the regenerative I Radio Esel,,si,vly Since 1921 detector for code reception. For the broadcast band (200 -600 meters) I have found that a very CLARK & TILSON, INC. CLAROSTAT./ selective single -control receiver loses its selectivity 1:_ CHAMBERS-STREET NEW YORK The Nntwnalb Kaum Hon. Reg. U. S. Pat. Off. on account of the difficulty of tuning the first Pleas e say you saw it in RADIO NEWS www.americanradiohistory.com 1 Radio News for January, 1929 699 stage. So I added one tube ahead of the three the They DUBILIERS ", tuned circuits; its amplification peaks between 400 "You Can Forget Condensers-If Are and 600 meters. This permits the three following stages to tune very sharply, and adds also somewhat Type PL 1120 especially designed for to amplification at the higher wavelengths. I find the Thordarson types R-480 and R -280 in this cir- Power Compacts, used with 171 type the 100,000 -ohm resistor indispensable tubes and the 280 type tube Rectifier cuit; because, even without an aerial, powerful or the Elkoes E -80 metallic Rectifier. stations like WGY, KDKA, WJZ and others come Price $15.50 in with such tremendous force as to be too loud even for a big hall. The Peridyne principle of stabilizing has been added, as well. The set per- There is JNo mits the reception of code on the short -wave set by using the potentiometer on the intermediate Substitute stages and permitting the set to oscillate. The condenser C, which serves as the short -wave For Quality! condenser or oscillator condenser, depending upon how the switch is turned, is .0005 -mf., and might NO amount of lurid claims be as high as .001 -mf., improbable as this might by nimble-penned ad- seem, provided its minimum is low enough. I use a Remler for the purpose and can go as low as vertising writers will take 13 meters. By putting a .0005 -mf. fixed condenser the place of in the in series with the "short -wave" set's secondary, quality that set can be made to oscillate up to 24,000 meters final analysis -the opera- using a 1200 -turn duo- lateral coil. Although the power circuit seems terribly complicated, if properly tion in your supply. placed it is simplicity itself and can be enclosed in a cabinet 24x12x8 without undue crowding. Ever since the advent of Of course, in this out -of- the-way part of the world, Radio, Dubilier has been where radio is our only amusement, distance -getters are welcomed and I have so far changed three the manufacturers' stand - Dubilier Light Socket Aerial standard sets for friends of mine. With this set ard-and the set builders' -"A Moulded Bakelite Product" we have music, speech or lectures during all hours of the day and cover both continents as well. I stand -by. Built in every Bringinprograms with aminimum am enclosing a letter of verification from the Dubilier is a of interference. Simply to British Broadcasting Company, London, on SSW. Condenser attach Coil data can be found by those desirous of factor of safety which is the set and plug into the nearest building this set in any good radio hook -up. How- your safeguard for years light socket. Uses no current. Sold ever, to help those who have no time to look it up, here goes. of service without failure. by all good dealers. Price $1.50. Coils V, 50 turns Advance resistance wire on a half -inch spool. Coils M ( "binoculars" 1% inches Write to Dept. 11 for in diameter each section) have 50 turns on each free catalog of good No. 22 enameled wire -wound in the same direction. The primaries have each 40 turns of No. 38 S.S.C. wire inside the binoculars close / terminals. These coils with their Dubilier to the filament 400 -turn chokes and .0005 -mf. condensers are en- Z'es closed in a copper box; the tubes are mounted on C O N D E N S E R top of this box and the triple condenser at the Reg. USPet.Off. side. No leads are longer than half an inch. On CORPORATION the other side of this condenser are the I.P. section and three tubes: the Yaxley switch and the oscilla- IO East 43rd Street New York City tor condenser are at the right of these, and finally the A.F. amplifier is at the end of the baseboard. The three dials are thus in a row on the panel, which carries also the two resistor controls, and the jack switch above the oscillator condenser. This is all except for the filament switch at the right. I have also found a pronounced improvement in short-wave reception which may be of interest to readers in the use of a 171A as the detector; DEALERS AND SETBUILDERS Fig. 2 THE NEW 1929 Catalog is crammed Mr. Van Koolbernen uses P/s volts on the full of the FINEST, NEWEST, na- plate -plus, of course, half the ".4" voltage. tionally -known A.C. sets, consoles, cabin- as compared with the center of the filament. ets, dynamic speakers, kits, eliminators, and accessories at LOWEST PRICES. not with the usual 45 volts upward, which caused the signals to be mushed, but by using a 1% -volt Largest stock of Radio Parts. Prompt "C" battery on the plate, with a 0 -8000 ohm delivery. Write for our FREE catalog. resistor in series (Fig. 2). With this, instead of WESTERN RADIO MFG. CO. a basket -weave coil 4 aerial and ground, I use 128 WEST LAKE ST. - Dept. RN -1 CHICAGO, ILL. inches in diameter and having 100 turns. With this three inches from the grid coil, and the circuit led into the intermediate and R.P. amplifier and a dynamic speaker, yesterday we had a band con- cert all day, to the surprise of the villagers -at least, to the owners of $500 sets. J. H. VAN KOOLBERGEN, Port Alfred, Quebec, Canada. Be an Expert RADIO OPERATOR Fascinating work. Wonderful opportunities. DX Good pay. Telepler Code Sender teaches you OPEN LABOR BRINGS THE at home In halt the usual time. Reproduces actual FAL Editor, RADIO NEWS: sending of expert operators. Sends you messages, JOBS The letter in the November issue from J W. radlogtams. etc. -regular code truffle anywhere, any time, any speed. U. S. Manning of Florida interested me quite a little. Navy and leading schools endorse Tele- At the time I read his letter I decided he was a ples as quick, easy, thorough. Complete ELECTRICITY little more successful in logging distance stations set Instruction tapes supplied at no extra 90 days fits you for big pay ELECTRICAL job at cost. Write for Booklet NR. $50 to $200 a week. All practical work on real equipment. than I was. TELEPLEX COMPANY MONEY-BACK GUARANTEE. Free Radio Course. Write When I constructed the Junk Box receiver in 76 Cortiandt St., Now York, N. Y. for GO -page FREE BOOK, and remarkable tuition offer. McSweeny Electrical School, Dept. 76 -W, Cleveland, Ohio Please say you saw it in RADIO NEWS www.americanradiohistory.com 700 Radio News for January, 1929 August I had no luck at all. Could only get a few stations on this side. I corresponded with a couple of fans and compared notes and then set to work FER again. Went over all connections (even the springs SAVE RANTI YOUR MONEY ! in the tube sockets.) Distant stations were still Audio Frequency going right by my set. Then one night I got BE YOUR OWN SERVICE MAN 5SW and the next night I got PCJJ. Since then TRANSFORMERS I have logged them quite a lot. Plenty of volume. THE RADIO From my experience I would say that most and short -wave operators fail to receive distance be- TROUBLE cause of one of the following reasons: (1) all con- THE RADIO' FINDER RADIO PRODUCTS nections are not tight; (2) they do not use care TRDUBLE fINDER enough in tuning the set; (3) they listen in at Even the highest - receive preference the wrong time. priced radio set In place of the condenser mentioned in the occasionally de- by engineers who KNOW July issue I use a small balancing condenser in velops a fault and the aerial lead. I do not notice much body capa- that at a time Real audio transformers with flat city-. Care should be taken to see that the rotor curves. Special output transformers plates when you least for all speakers and tubes. of both tuning condensers connect with the High filament. I find that the signal is just as strong expect it -maybe grade iron core chokes for "B" right in mid- Eliminators. Three range portable and the ground hum is decreased a lot if the the meters. 1,000 ohms per volt. 10/50/ ground wire is disconnected. die of an interest- 250 scale. Three range portable One thing I do not understand however is the ing program. But, meters. 200 ohms per volt. 150173.4 fact that I receive 5SW on 12 using the seven - a handy copy of volt and 15 Mill. scale with switch. turn coil. All the coils tune much higher than 'The Radio Trouble Finder is the sim- By -Pass condensers -2MF--400 volt the article mentions. and 200 volt. ple means for tracing every defect and ARTHUR F. BROWN, remedying it in the easiest manner Circulars sent on request. 50'A Conant Street, Danvers, Mass. possible. There is no mishap that could (On short waves, a slight difference in the self - befall a radio, Send 15c in coin for copy of 1929 capacity of the coils, which is governed by the spac- but what is fully covered Ferranti Year Book. ing, and of the leads will produce a considerable in this valuable book. difference in the range covered by the coils. The The FERRANTI, INC. Radio Trouble Finder is edited condensers, also, may have a larger capacity than by men fully versed in the subject 130 W. 42d St., New York, N. Y. specified.- Enrros.) covered -men with years of actual ex- perience FERRANTI, LTD. FERRANTI ELECTRIC behind them -and who have Hollingwood, HOW TO SUPPRESS CAR NOISES grown to prominence since the infancy LIMITED of radio. England Toronto, Canada Editor, RADIO NEWS: N. J. K. of Salinas, Kansas, who writes in the Don't wait till your set goes bad -get November issue of RADIO NEWS, is harboring a your copy of this remarkable guide to resentment against the amateur which is entirely radio trouble now. Fill in the coupon Send For This Book - without foundation. His theory of eliminating and we will send you by return mail a interference by eliminating the amateur is a poor copy of The one and does not show a co- operative spirit. The Radio Trouble Finder, It Offers More Prof. amateurs are bothered by broadcast- station harmon- a money- saving investment. You can ics, yet we cannot use malicious methods to remove be your own service man. its to Set Builders them. Whenever a Ford goes rattling by the house, there is a louder rattle in the phones, due to the sparking between the coil points. The railroad The Copy crossing signal is another source of interference. 25e BARAWM , THE OLD RELIABLE Any of these things can cause the operator's hair to whiten; but we cannot use strong -arm methods sfnvrcE against them. IADIO The amateur bands are narrow, and after Janu- BUILD YOUR ary 1 very narrow; and there are several thousand OWN R d10 Fang, from nyh ekwheq'will stations in each of them. some of t ë exceptional ecru o th t Barawik rendered If your igter- radio pert, w like pulling bens' ference is from short -wave navy stations, what do RADIO SET teeth. First upon the scene. Barawik uwasalwat he newest development.in radio you propose to do? ready tudeliver: dodays when shyers 150 fast and furious. were I would advise Mr. K. to visit some nearby RADIO Today Barawik ha. grown anion go be mighty losti. amateur station, and read the license with regard HOOK -UPS the din world. proved. reliable rof the World'. lead- to silent hours. They are effective only when a ing radio maeufturera- everrything from eon. This is the latest Veto meta to the Smallest individual written notice has been received from the super- necessary to the set budder. You mina depend visor of radio. Sunday silent hours are in the issue of this re- e reliability of Barawik goods. You casi án d upon Barawik's ability to deliver the morning and not in the afternoon. When W. J. markable book. that mete, time saved in wait- ipS.iYov a depend upon Barawik's honesty, K. suggests the "vacuum- sweeper" stunt, I get bd ty and welint, Absolutely new but far to eery >u Ana, Wt, from lent, youyo know thatn Barawis the impression that he is about eleven or twelve and up - to - date. big discounte assure you of the lowest prices years of age. Perhaps he would remove a rail from ..- huge wrings to you ip All the best cir- everything you buy. the car track in order to insure peaceful slumbers. u. cuits of the day. W nrroof- rready you In short, the amateur is blameless in this in- ne mi enuder now for big new Cataog -Fe stance; his transmitter is operating in the authorized Full instructions bands. Our critic's receiver is what's wrong. As on how to build. BARAW I K CO. long as it receives his main wave, how can be Make your own it I C Canal Sta., expect the ham to remedy the trouble? That was set from the dia- CHICAGO, a bad bedtime story; it didn't put us to sleep. grams shown in Please accept my U.S.A. 900 thanks for printing C. Sterling 150 Radio Hook - te -." .. Gleason's stories; he can certainly write in an Ups. Write today -pick the set amusing manner. I wish you would print "The you want to .sng" Dildtg''' OttS. Wonderful Battyometer," by this author (We do build and make it. Then not know it -has Mr. Gleason been holding out you are sure to be satisfied with the 011 us?) results you get. More "A" Power I am glad you are not disregarding the amateur 150 Radio Hook -Ups was prepared by For as many other magazines are. We are willing to the staff of Radio News. An accurate Less Money! co- operate with the B.C.L.s but, if we do not guide to better set construction With the Set Builders discount know that the are interfering until we get a for the card you can purchase a letter from the supervisor, how are we apt to radio "fans." KNAPP "A" POWER KIT improve our sets? at a liberal discount. Roy A. JENKINS, W6CBY, 1449 Warren Ave., Long Beach, Calif. The Copy Write me today for full detailstelling about 25c thisnewmoney- saving planfor setbuilders. DAVID W. KNAPP, Pees. AMATEUR SHORT-WAVE BANDS MAIL THIS COUPON NOW Knapp Electric, lac. The new radio amateur regulations, for the first Division of P. R. Mallory & Co., Inc. time, make provision for television and operation CONSRAD CO., INC. of picture- transmission which is to be 230 FIFTH AVENUE NEW YORK, N. Y. (Room 417, 350 Madison apparatus, Are., N. Y. C. permitted in the bands between 60,000 and 56,000 kilocycles (5 to 5.35 meters) and 2,000 to 1,715 CONSRAD COMPANY, INC. kilocycles (150 to 175 meters.) 230 Fifth Avenue, New York, N. Y. - - Gentlemen: No change is made otherwise in the bands assigned Kindly send me a copy of 150 RADIO HOOK - to amateurs, which are: 401,000 to 400,000 kilo- UPS...THE RADIO TROUBLE FINDER... cycles (0.7477 0.7496 (check which or both). Set Builders -Dealers! Save Money! to meters); 64,000 to 56,000 Enclosed find cents in full payment. Send for the most complete book of nationally known kilocycles (4.69 to 5.35 .meters); 30.000 to 28,000 Parts, Kite Cabinets, Consoles. Speakers, Power Units. Name Sets eta. All at lowest wholesale prices. Quick service kilocycles (9.99 to 10.71 meters); 16,000 to 14,000 on an your needs. Write 110W, lt I. FREE- kilocycles (18.70 to 21.40 meters); 8,000 to 7,000 Address SETBUILDERS kilocycles (37.5 to 42.8 meters); 4,000 to 3,500 SUPPLY CO. City State AA 13 8 Ramberg Rig. Maässe and Martel Sts. CHICAGO,IIL kilocycles (75 to 85.7 meters), anal 2,000 to 1,500 kilocycles (150 to 200 meters). The bands for Please say you saw it in RADIO NEWS www.americanradiohistory.com Radio News for January, 1929 701 amateur radio -telephone operation remain, as here- tofore, from 64,000 to 56,000 kilocycles (4.69 to 5.35 meters), 3,550 to 3,500 kilocycles (84.50 to Tune In on the 85.7 meters), and 2,000 to 1,715 kilocycles (150 to 175 meters). An amateur station is defined by the commission Short Waves as a station operated by a person interested in Get didalH e- escape static nn the lung ware broadcast band. See Call Book for short wave stations. SUBMARINER wave radio technique solely with a personal aim and band includes all powerful stations that broadcast pro- with no pecuniary interest. Amateur licenses will grams not be issued to stations of other classes. its waves area they new adventure-anew thrill awaits Amateur stations are authorized for communi- you. cation only with similarly licensed stations, on Short Waves Popular wavelengths or frequencies within the bands set The SUI13IAI1INER has taken the country by storm. Noth- and at all times unless interference is caused with ing made like it. Many users have been getting London, England; many get Rolland, even in summer. Short waves other radio services; in which event a silent period are great distance carriers, with less static. must be observed between the hours of 8 and 10:30 p.m. local tittle, and on Sunday during local church services. Spark transmitters will not be authorized Best of An Your present radio. receiver, whether battery operated or for amateur use. all electric, will bring in short wave broadcasting when Amateur stations must use circuits loosely used with coupled to the radiating system, or devices that will produce equivalent effects to minimize key and plate -supply modulations. THE SUBMARINER impacts, harmonics It is easy to connect a SUBMARINER. Simply remove a Conductive coupling, even though loose, will not tube from receiving set and place in SUBMARINER socket; to clips on SUBMARINER. be but this restriction shall not apply then insert SUBMARINER plug in place of tube. Attach regular aerial and ground permitted; That's all. No changes in wiring cf set necessary. No additional tubes or batteries required. If set operates a against the employment of transmission -line feeder loud speaker, it will do so with SUBMARINER. We guarantee that the SUBMARINER will operate within systems to IIertzian antennas. the wave band covered equal to any short wave receiving system known when attached to your receiver. Com- pletely shielded metal cabinet. Fine tuning dial, ratio of 32 to 1. Get the short wave musical programs and Amateur stations are not permitted to communi- other activities, including television signals. Never before has so much in radio been offered foe so little money! cate with commercial or Government stations unless Order a SUBMARINER nowt authorized by the licensing authority, except in an emergency or for testing purposes. This re- FOUR MODELS 160 meter range does not apply to communication with 20 to 05 meter range -for battery operated radios. $15.00. For all electric radios, $17.50. 10 to striction -for battery operated radios, $822.50. For all electrio radios, $22.50. 10 to 160 meter range models have three small pleasure craft, such as yachts and motor interchangeable coils. boats holding limited commercial station licenses, If your dealer does not carry, order direct from factory. Sent anywhere in the U. S. postpaid upon receipt of which may have difficulty in establishing communi- price. Canada and Foreign, 60c additional. Money order only. Also sent C.O.D. plus postage In U. S. if $1.00 stations. accompanies order to insure carrying charges. In ordering be sure to name set and tubes used, such as UV -199, cation with commercial or Government US199, 22O1A, UX226, or UY227. See dealer or order direct today. Amateur stations are not authorized to broad- cast news, music, lectures, sermons, or any form of entertainment, or to conduct any form of com- JM -P MANUFACTURING CO., Inc. mercial correspondence. 3405 Fond du Lac Ave. Milwaukee, Wis., U. S. A. No person shall operate an amateur station except under and in accordance with an operator's license issued to him by the Secretary of Commerce. Makers O/\ of high MASON, FENWICK & LAWRENCE JUNIOR CORRESPONDENCE SEEKERS R® quality PATENT LAWYERS Editor, RADIO NEWS: resistors and F. N. W., WASHINGTON, D. C. and 600 ST. I am a short -wave fan of sixteen years condensers that are ESTABLISHED OVER SIXTY YEARS -SEND SKETCHER greatly enjoy "On the Short Waves." I have a Built Better - to endure. Electrical and Chemical Inventions Carefully in Cuba to tune short as Handled. Practice before the U. S. special set made here Write for The Research Worker. Courts and the Patent Office. and a Grebe S.W. set too. well as long waves, A free monthly publication. Prompt and I would like to correspond with other short -wave AEROVOX WIRELESS CORPORATION Carelut SrrMce Trade -Marks Registered fans of any age or experience, as I know some- OB Washington Street Brooklyn, N. Y. thing about radio. ' SILVIO IIERNANDEZ, Colle 27, No. 89, "entre D y E," Vedado, Habana, Cuba. RADIO NEWS FREE BLUEPRINTS Nos. 71, 72, 70, 55 and 58 Editor, RADIO NEWS: TO encourage the construction of radio apparatus illustrated in this mago- I would like to correspond with experimenters in zinc, and make it easier for our readers, RADIO News makes up each radio and its associated sciences, especially tele- month large blueprints of the diagrams which accompany the principal con- vision. structional articles; these sets include full-sized drilling templates, coil data, J. R. HARRISON, JR., etc., where required, and in each case a list of the apparatus originally used, 216 Lorraine Arc., Upper Montclair, N. J. with full specifications. Several thousand of these have been distributed each month. Editor, RADIO NEWS: If you desire a set of blueprints for any or all of the apparatus described I would like to exchange letters with boys of in this month's Free Blueprint articles, fill out the enclosed coupon as directed about 13. and send it in. The blueprints requested will be mailed to you without DONALD BUZZELL, Leaf River, Ill. charge, postpaid. We cannot send blueprints with magazines, or accept in- definite requests for blueprints to be issued in the future. Delay will be caused by failure to use this form, as this publishing office has many departments. TELEVISION EXTRAORDINARY 7 AHD -- Now 1 íROA5t LAMA!/ i See THE LAMB; ?O- Yij,! I, Blueprint Department, RADIO NEWS: (B) ttt 230 Fifth Avenue, New York, N. Y. (U. S. A.) I am interested in constructing the following apparatus described in RADIO NEWS for January, 1929. Please senti me a free set of large blueprints for each of the items checked. No. 71 The "Bloopless" One -Dial Two -Tube Set. No. 72 The "Lamp- Socket Five." Operating hint from the New York Times of No. 70 An Adjustable "B" Power Unit. August 26: "To reverse the manner in which No. 55 An "Extension" Two -Tube Audio Amplifier. as the the neon LAMB plate is scanned-" Or, No. 58 The "Junk -Box" Short-Wave Receiver. poet has it: "Mary has a little lamb; \\-hose fleece looks pink as neon; It televises just that way, Name Whichever side you see on." -Rudolf Sturm. Street Number QUIT YOUR CROWDING, BACK THERE! We are anticipating some development along the Postoffice line of television that will bring it right to the front in public interest, since reading this in the Philadelphia Inquirer of September 16: "Radio State (Province, etc.) Equipment: BATH-TUB, enameled, awning of canvas, store front size, good cond., cheap." Yes sir, when these bathing beauties come on the (Please typewrite your name and address or print it with a pen -not a pencil-as screen, the other stations may as well stand by. -Charles Meister, Ir. many signatures cannot be read. This will avoid errors in addressing the mail.) Please say you saw it in RADIO NEWS www.americanradiohistory.com 702 Radio Ncws for January, 1929 -n OPPORTUNITY AD -LETS Follow these advertisements every month. Reliable advisers from all over the country offer their most attractive specials in these columns. Classified advertising rate twenty -six cents a word for each insertion. Names and addresses must be included in 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. Advertisements for the March issue must reach us not later than January 1st. CIRCULATION LARGER THAN THAT OF ANY OTHER RADIO PUBLICATION EXPERIMENTER PUBLISHING CO., INC., 230 Fifth Avenue, New York, N: Y. Agents Wanted Male Help Wanted Patent Attorneys (Cont.) $1 Pays $20.00. Start This Fastest Big Money Busi- Firemen, Brakemen, Baggagemen (white or colored), Patents -Send drawing or model of your invention for ness making World's newest selling specialties. Have Sleeping Car. Train Porters (colored), $150 -$250 monthly. examination and instructions. Advice and booklet free. ethers settings them. Eye- opening literature describing Experience unnecessary. 237 Railway Bureau, East St. Highest references. hest results. Promptness assured. Guaranteed Formulas. Latest Valuable Trade Processes I.ouis, Ill. Watson E. Coleman, Patent Lawyer, 724 9th Street, N.W., Free! Small Investment. Profit Immense. Start Any- r. a. e...,...... o ...ero.a.....ra...oe.eoammmmae. aces...... o .oa.o.....ro,a.o.aa.,.nnnn.rmnm Washington, D. C. where. Miller, Chemist, 706 -R Jetton, Tampa, Florida. Miscellaneous Patents-Free instructions. Former Patent Office Ex- Guaranteed Genuine Gold Leaf Letters anyone can put on aminer. Moderate terms. Booklet. Albert Jacobs, 740 Barrister Bldg., Washington, D. C. store windows. Large profits, enormous demand. Free Forma to Cast Lead Soldiers, Indians, Marines, Trap- Chicago. samples. Metallic Letter Co., 922 N. Clark, pers, Animals, 151 kinds. Send 1Oc for illustrated Cata- logue. H. C. Schiercke, 1034 72nd St., Brooklyn, N. Y. Patents-Send for form "Evidence of Conception" to be Agents -$50. Weekly Selling Shirts. No capital or signed and witnessed. Form, fee schedule, information free. experience needed. Commissions in advance. Samples Lancaster and Aliwine, Registered Patent Attorneys In Inventions Commercialized. 'Patented or Unpatented. United States and Canada, 269 Ouray Bldg., Washington, Free. Madison Products, 560 Broadway, New York. Write Adam Fisher Mfg. Co., 278 Enright, St. Louis, Mo. D. C. ...e...r.,.....,...... r...... ,...... ,.....,..,..,.r,.,..r.,...... ,..,,,.e..,..r..,.,r..,.rr.r..rr.r...s Copyrighted game awaits manufacturer. Two thousand nnanmnaam.em.rnrmemn.mnmrnmrar.r..rr.r..r..r..,..,..r..r..,....r..r,.r.....r..,....,.re..r....r ...... cash. Darrel Fessel, Amsden, Ohio. Books Patents Guaranteed Solder for Aluminum, Mail, $1. Piensan, Books, Magazines. Art Publications in French, Spanish Belmar, N. J. Inventions Commercialized. Patented or unpatented. English. Photo novelties, samples, lists, etc., 20 cents ,u.,.n..,....,e., .er,.,.e,.ee.....,...e,e,...... r. r,... nrrr r,rrrer.r,.r..r..re.e.er..,ee. Write Adam Fisher .Mfg. Co.. 278 Enright, St. Louis, Mo. stamps. Villaverde Co., Dept. 211, Box 1329, Havana, Cuba. Motorcycles Printing, Engraving and Multigraphing Used Motorcycles. Low Terms. Also Parts. Accessories. Catalog Free. Western Motorcycle Co., 946 East 15th St., 200 Letterheads and 100 Envelopes, $1.10, postpaid. Business Opportunities Kansas City, Mo. Oberman Company, Box 1042, Chicago. ,,,,,.....,. ...,..r ...... nr,.n...... ,.,,,,,,,n,,,,n,,...,.,,. nee..,,...... ,,.. ,..r..r.,..,..,.n....,,.,,n..,, ..r..nrr..n.r.n.n.n.n.n.n.n.rrlae.Imumuuuvue..u.u.r..rr.n.n.t..r.u...... u....r..r....r.r...... rr..r....r....r Free Book. Start little Mail Order business. Hadwil, 5A -74 Cortlandt Street, N. Y. Old Money Wanted Radio Amateur Cartoonists: Sell Your Cartoons New Plan. of Smith's Service E \1194, Wenatchee, Wash. $2 to $500 each paid for hundreds Old or Odd Coins. Edison Storage B. Batteries 100 volts Kits $6.50 A- Keep all old money, it may be very valuable. Send 10c volts Value Book 4:6. Guaranteed Eliminators Cost $35.00, $9.00 It-Eliminators 150 or Unpatented. for New Illustrated Coin $12.50 Battery chargers $3.50 cost $13.50 Cone Speakers. Inventions Commercialized. Patented Get posted. We pay Cash. Clarke Coin Com- St. 310. prices. t/a Horsepower $7.00. Write Adam Fisher Mfg. Co., 278 Enright, Louis, 14 Street, LeRoy, N. Y. Units $1.00, Motors 904 North pany, Fifth, Philadelphia. ome.mre.r ...... r...... ,.. One Peridyne and one Ultradyne cheap. F. L. Hanson, Chemistry '==Q-Q-Q-q=z=-Q=1 Ilion, N. Y. Learn Chemistry at Heme. Dr. T. O'Conor Sloane, Radio Troubles are frequently caused by tarnish on noted educator and scientific authority, will teach you. Our plugs or tube prongs. Jasper Polishing Powder Is ideal home study correspondence course fits you to take a position for cleaning contacts. 4 oz. can 35c., Postpaid. Jasper as chemist. See our full -page ad on page 672 of this 100 Co., Jasper, Minn. issue. Chemical Institute of New York, 16 E. 30th Street, New York City. Dri "A" Eliminator, $16.00; ABC, $20.00; B- Elimi- Ori Eliminator, ABC, B- Eliminator, a..,....,....m ...... mmn.r.....,.r,.,.....,....r,... n "A" $16.00; $20.00; Read! 4 taps, 180 volts, $10.00, 50 milliamperes. Lowest prices in America. Above are set builders' discounts. Catalog 58. Correspondence Courses Electro- Chemical Company of America, Indianapolis, Ind. Opportunity Ad -Lets Bargains, used radios. Guaranteed perfect working Used correspondence school courses sold on repurchase order. Blue Ribbon 5 tube, 2 dial, Console $19.95. basis. Also rented and exchanged. Money -back guarantee. Freshman $14.95. Atwater Kent $19.50. Tubes included. Catalog free. (Courses bought). Lee Mountain, Pisgah, Many famous makes. Send money order with order. Alabama. Who knows but that Bargain list on request. Surplus Radio Co., Dept. 2, 599 S. Wells, Chicago. the opportunity of your Wanted: Men to work with National Radio Service Detectives lifetime may be hid- organization. No selling scheme. Radio Doctors, Inc., Dept. N. Essex St., Salem, Mass. Detectives Needed Everywhere. Travel. Experience un- den in one of them. necessary. Particulars Free. Write, American Detective System, 2190 Broadway, N. Y. Read them each month Representatives Wanted M111111111. -they can easily be turned to earning dol- f Representatives Wanted for B power based on a new Esperanto principle. Patented and guaranteed. Ideal for all sensi- lars and cents for you. tive receivers including screen -grid and short-wave sets. Send for free illustrated sample lesson of the interna- Colo Manufacturing Co., 27 Homestead Ave., New t ional language, Esperanto. It immediately enables you Harem... to correspond with all nations of the world. Benson Ct...... r.,.,...... ,...... r.. r.... r....,. r...... ,,r...... ,,,.,. School of Esperanto, 518 Broad Street, Newark, N. J. Song Writers For Inventors Song Poems Wanted: Write at once. Valuable instruc- Patent Attorneys tion book given free! Bell Music Co. D -11, St. Louis, Mo. Inventions Commercialized. Patented or Unpatented. Write Adam Fisher Mfg. Co., 278 Enright, St. Louis, Mo. Patents procured at reasonable rates with time to pay. - Sales negotiated. Staff of registered attorneys and en- Telegraphy If you have a good invention, write Hartley, Box 928, gineers. A complete service for inventors. Write for Bangor, Maine. particulars. Inventors Service Bureau, Union Trust Bldg., Telegraphy -Both Morse and Wireless taught thoroughly. Washington. D. C. Big salaries. Wonderful opportunities. Expenses low, chance to earn part. School established fifty years. Cata- Valparaiso, Ind For Sale log free. Dodge's Institute, Cour St., Alfalfa Seeds, hardy common rarities $8.90. $10.20, $12.60 bushel; Grimm variety Alfalfa seed $18. Scarified street clover $3.90, $5.20 ; Alsike or red clover $15. NEWS to Set Builders Bags Free. Send for samples and catalogue. Kansas Seed Co., Salina, Han. Patents-Time counts in applying for patents. Don't Barawik offers set builders bigger risk delay in protecting your ideas. Send sketch of model bargains - bigger opportunities to make free book, "How to money this season. New seta, new kit for instructions or write for Obtain dynamic a Patent" and "Record of Invention" form. No charge for ideas, all the leading parts, supplies, etc. Lowest rock - . Help Wanted- Instructions information on how to proceed. Communications strictly speakers, bottom prices. Bigger stocks, quicker confidential. Prompt, careful, efficient service. Clarence Beek today free. A. O'Brien, Registered Patent Attorney, 309 Security service. Send for Big Bers.In Wanted Immediately, names of hard -working men and Canal women, IS to 55 who want to make more money. Write, Bank Building (directly across street from Patent Office), S.A. Instruction Bureau, 251, St. Louis. Mo. Washington, D. C. BARAWIK CO C.c w.,..oe.,.,e.....r...... war,...... re,.,..r ...... o...ee.. tam,.rm.r. sew e...... o.o...... Mail This Coupon Now! For Free Copy Instruction Name Learn Chemistry at Home. Dr. T. O'Conor Sloane, noted educator and scientific authority, will teach you. Address Our borne study correspondence course fits you to take a position as chemist. See our full -page ad an page 672 Patent Sense -Valuable book free. See Lacey's ad. page of this issue. Chemical Institute at New York, 16 E. 30th 678. Lacey & Lacey, 631 F. St., Washington, D. C. Street, New York City. Established 1869. www.americanradiohistory.com Radio News for January, 1929 703 Radio News Laboratories (Continued from page 659) tuning control is a drum approximately, 5 inches r' -. volume -control knob is found at in diameter; the 111 \ oi the left and the switch is located on the O / !/¡/ power right side. The three R.P. tubes and detector III are provided with special shield cans to prevent electrostatic coupling. Provision is made on the chassis for supplying direct current at 100 volts to a dynamic speaker. The chassis is enclosed . within a brown crystalline sheet steel case, the top ( I IS .. of which is removable. Connection to the antenna, u:. 4 `' ground, and loud speaker is made by pin tip jacks. ADJUSTABLE An extension of ten feet is provided for connection to the light circuit. The housing is 21% inches N long, 9% inches high and 13 inches deep. Ample selectivity and sensitivity was demonstrated with CARBORUNDUM DETECTOR excellent reproduction over the audio frequency / scale. AWARDED THE RADIO NEWS LABORA- ATURN of the pressure screw -gives you perfect tone balance. TORIES CERTIFICATE OF MERIT NO. 2483. position is fixed by adjusting lock nut, so that pres- sure remains permanently sensitive. QJust another improve- MICROPHONE ment to further insure the Perfect Tone Quality you always get The microphone submitted by Ferdinand Schuch- hardt, Berlin S.O. 16, Germany, is of the six - with the Carborundum Detector-and tone quality is every - button carbon -diaphragm type; the diameter of the thing. Q Recommended by noted radio -circuit designers. diaphragm is 1 ;8 inches. With the application of milliamperes through the various buttons, they 50 DEALER OR DIRECT S. A. did not pack; while the sensitivity is such that -$1.50 IN U. external noises were not prominent. The measured Send for Free Book "Carborundum in Radio" D-1 The Carborundum Company, Niagara Falls, N. Y. Canadian Carborundum Co., Ltd., Niagara Falls, Oat. Cr T'T,' g se the lregiete"d TnV.V. The Cille anddum Comrye, top Ice SLLlaoa Carbide and Is i Synchronous Motors for Television resistance of the submitted sample is 117 ohms; In addition to building reliable and satisfactory motor gene- when it is used with the companion modulation transformer, a variable resistance of 100 ohms rators, "Esco" has had many years of experience in building should be employed to insure the proper sensitive- electric motors for a great variety of applications. ness of operation. The six buttons are mounted, and protected from injury by enclosure, in a molded composition housing, having an aperture of l'A inches in its center. The housing is 5V,, inches in external diameter and 34-inch thick. A Synchronous motors, small, compact, foot, 1% inches in height and 3% inches in dia- reliable, self- starting are now offered meter, is fastened to the housing; a double con- nection cord, six feet in length, is fastened to a for Television equipment. They re- terminal block inside the foot. When used in connection with the microphone very good repro- quire no direct current for excitation, duction of speech and music was obtained from the are quiet running and fully guaranteed. audio -frequency amplifier of a radio receiver. AWARDED TIIE RADIO NEWS LABORA- TORIES CERTIFICATE OF MERIT NO. 2484. Other types of motors suitable for MODULATION TRANSFORMER Television may also be supplied. The modulation transformer submitted by the same manufacturer has been designed for use in Write us about your requirements. connection with the microphone described above. ELECTRIC SPECIALTY CO. 211 South St. Trade "ESCO" Mark Stamford, Conn. It has a winding ratio of 1 : 50, and is of the unshielded, shell -core type. The D.C. resistance of the primary was found to be 44 ohms, and the resistance of the secondary 12,500 ohms. It is mounted to a base board with the wood screws Ne,vest radio hoos -ups. Pli!. provided. When it was used as recommended, book shows how to make Broad- the audio -frequency voltage amplification was found cast and Short -Wave Receivers, to be practically the same at all frequencies. 'V und Short -Wave adaptera. AWARDED THE RADIO NEWS LABORA- Barawik, the first and oldest radio Ifow to use the new screen- specialty house, offers you unusual grid tube In D.C. and A.C. TORIES CERTIFICATE OF MERIT NO. 2485. service this year. Bigger stocks, circuits. quicker shipments, lower prices. FREE Bow to build Power Ampli- Deal with an old established, reliable fiers. and ABC Eliminators. Up- house. Get honest goods, honest service, to- the -minute Information on all AMID THE BURNING LOGS honest prices. Barawik service makes you radio developments. more money. Send now for big new Catalog show- 11CwSet Builders, Fans, Dealers. Warm Southern welcome was given to the Radio ing lowest wholesale prices. send for it today: Commission's new list, as the Jacksonville Times - Union testifies: "The reallocation plans of the BA RAW I K CO. C2rato,lerS: %1. KARAS ELECTRIC COMPANY 4038A3 4038A3 N. Rockwell St., Chicago, Illinois body were FIRE announced in the Tuesday Mail This Coupon Now for Free Rodio Guide federal Please Free Book! edition of the Florida Times -Union." Or, perhaps, send me your allusion is made is to some of the stations which Name Address were eliminated from the ethereal realms on high. Addresa -R. H. Rice. i'Ily tate Please ,ray sazv it in R.1DIO Ar wS www.americanradiohistory.com 704 Radio News for January, 1929 11.6416s WHOLESALE PRICES pAG ces be- On Everything e This big cat"'te of t cmost fore qa gest óandiokits, - in stock con RADIO try's fete and the c accessottesonas e pamp+ well soles as d seasonf tab,both A-C an 1DCteivets.Ef ry t sethou dealer, rested tn radio should sendfof her copy mense átalog. IR AIDII(D SIEIRVIICIE Allied Service will prove a revelation to you in what radio service can really be. Allied Executives backed by years of training in radio,are practicalmen. They know radio. Their vast experience has built up around them an organization trained to serve. Months of effort have built up a tremendous reserve of stock that makes for prompt shipments; and this stock is new stock comprising the season's pick of such prominent manu- facturers as Silver- Marshall, Tyrman, Aero, Hammerlund- Roberts, etc. SET BUILDERS: Set Builders, Amateurs and so- called "Hams" will delight in the unusual variety and remark- able values that are offered in standard kits and parts. Tremendous stocks -real organization - prompt shipping service all combine to make Allied your ideal source of supply. RADIO DEALERS: The live radio dealer -the man who keeps pace with the rapid advance of radio -will find much of real interest in the Allied Catalog. New A -C Sets, D -C Sets, Dynamic and Magnetic Speakers, Television equipment, in fact every- thing an impatient radio public is demanding. Write for Catalog Now! AlliedCORPORATION Radio III W. LAKE ST. Dept. B -3 CHICAGO Please say you saw it in RADIO NEWS www.americanradiohistory.com R,papßiqDividends fromthisInvestment inToneQuality A Thordarson Power Amplifier (Home Constructed) Will Transform Your Radio Into a Real Musical Instrument WITH the insistent demand for the wiring of the receiver itself, attach- quality rcproduction, power am- ment being made by means of a special plification has become a vital radio ne- plug which fits the last audio socket of cessity. 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The discriminating contains detailed specific home con- construction data on success in home construction. structor will do well to follow the lead twelve individual power Whether your present receiver is fac- of these manufacturers when buying units, with clear -cut lay- tory made or custom built one of these his power amplifier. outs and diagrams of each. amplifiers may be attached with equal Write to the factory today, enclosing 25c Send 25c in Cash or Stamps ease. In fact, most Thordarson Ampli- 25c for the new "Power Amplifier for This New Book - fiers require absolutely no changes in Manual" -just off the press. Just Off the Press! MAIL THIS COUPON TO Mt TRORDARSON ELECTRIC MANUFACTURING CO. 500 West Huron Street, Chicago, Illinois Gentlemen : Please send me your new "Power Amplifier Manual" for which I am enclosing 26c. Please send me free of charge your instruction sheet on the amplifier I have checked below: MORDARSO 171 Single 171 D. Push -Pull D. 210 Single D. 210 Push - Pull (1 Stage) 0. 210 Push -Pull (2 Stage) 0. 250 Single (1 Stage) D. 250 Single (2 Stage) D. 250 Push -Pull (3 Stage) D. TRANSFORMERS 210 Phonograph Amplifier D. Name IN MUSICAL PERFORMANCE Street and No SUPREME Town State 8688 f www.americanradiohistory.com .r rf 6_. wFS ,. v., Radio Manufacturers Since. . 1908 The name PILOT stamped on a radio part guar- antees scientific engineering and precision manu- facture. You can secure Pilot Precision Radio Parts only at the better type dealers. RADIO DESIGN Fifty cents coin or stamps brings you 'PILOT this Bigger and ELECTRIC t$fV.CLRINC Better Construc- 323 Berry Street tion quarterly for Brooklyn, N. Y. one entire year. World's Largest RADIO DESIGN 103A Broadway Radio Parts Plant Brooklyn, N. Y. www.americanradiohistory.com