. -

=1".1

www.americanradiohistory.com the perfect tonic for your radio Is your set "run down" after long, constant use? The finest radio tonic known is to install a correct, new tube in every socket of your set. One inferior or old tube may be crippling your set and causing poor reception. Have your dealer test your tubes and install new, wide -awake Cunningham Radio Tubes to replace the old ones. E. T. CUNNINGHAM, INC. NEW YORK CHICAGO SAN FRANCISCO

Manufactured and sold under rights, patente and inventions owned and /or controlled by Radio Corporation of America.

',NADIO TUBES

www.americanradiohistory.com Radio News for July, 1928 1

Follow the Example of Thousands --Join the Radio Association -Learn Radio -Take Advantage of its Big -Pay Opportunities

ASSOCIATION OF Doubled His Income in Two Months You will have the benefit of proven busi- THE RADIO ness- building plans. Our Employment AMERICA will help you make Member W. E. Thom, Chicago, was a Service will be at your disposal. You money in Radio, full or part -time. It clerk in a hardware store when he joined will have the privilege of buying radio will teach you how to build and repair the Association. The training we gave parts at wholesale. You will have the the manager- in business, if you wish. him enabled him to secure Association behind you in carrying out sets; start you ship of the Radio Department of a large your ambitions. store at a 220% increased salary. "I attribute my success entirely to the You the No -Cost Earned $500 in Spare Hours ACT NOW-If Want Radio Association," he writes. "Your Membership Plan method of instruction is wonderful." of members earn $3 an hour Hundreds Membership in the Association has in- Now is the time for you to join. The serving their communities as "radio creased the salaries of innumerable men. success of the Association was so tre- doctors." Member Lyle Follick. Some turned their extra hours into cash, mendous during 1927 that we are still being "radio doctors" for their neighbors; able to offer a limited number of Mem- Lansing, Michigan, has already made others by accepting employment with $500 in his spare time. Member berships that may not -need not-cost neighborhood radio dealers. Scores of our you a cent. To secure one of them, write Werner Eichler, Rochester, N. Y., is members are now connected with big today without fail. We will send you earning $50 a week. Member F. J. radio organizations in different capacities. details, and also our book, "Your Oppor- Others are proprietors of prosperous tunity in the Radio Industry," that will Buckley, Sedalia, Mo., is earning as stores. in his spare time as he open your eyes to the possibilities in Radio much money us from you at once. receives from his employer. for you. Let hear From Clerk to Owner The Association will train you to be a "radio doctor" and to build sets "tailored" "In 1922 I was a clerk," writes Member to your neighborhood needs, that you can K. O. Benzing, McGregor, la., "when I RADIO ASSOCIATION OF AMERICA sell for less than the "ready-made" sets enrolled. Since then I have built hun- 4513 Ravenswood Avenue III. RN offered by your local dealers. dreds of sets-from 1 -tube Regenerative Chicago, Dept. -7 to Superheterodynes. Gentlemen: "I am now operating my own store and Please send me by return mail full We Will Start You in Business my income is 400% greater than when details of your Special Membership I joined the Association. My entire success Plan. and also a copy of your book. "Your Opportunity in the Radio In- If you prefer a business of your own is due to the splendid help you have given dustry." to becoming a Radio Engineer, our co- me." operative plan will start you in a business of your own without capital. Membership Privileges Name This plan gives the ambitious man his opportunity to establish himself in his If interested in Radio as a profession or community. a profitable hobby, join the Association. You will receive a comprehensive and Many have followed this plan and estab- practical training in Radio that will fit lished radio stores. you for Radio's big -pay opportunities. stlt^

www.americanradiohistory.com l Radio News for July, 1928 ,,/ 41/,4_"AA-144.1,/ NE WS Volume 10 JULY, 1928 Number 1

Contents of This Issue

"Radio Concerts" By Hugo Gernsback 7 ¡ The Radio Beginner -A Cheap, Practic- able Receiver "Sure, 'Then? Was the Happy Days" ( ?) -The Crystal Set 33 By Charles Magee Admits 8 A "Junk Box" Short -Wave Receiver Radio Behind Prison Walls By Robert Hertzberg 36 By 011ie Meloay, No. 52(107 10 A.C. Tubes Require Special Wiring Care 39 Radio Aids Marine l'ire Fighters 12 A Sturdy and Dependable "B" Power Unit 40

The Passing of the Third -Floor Quack Improving Reception on a Thin Pocket- By Robert Francis Smith 14 book By Luther C. Dilatush 44 How Many Stations on One Wavelength? RADIO NEWS Monthly Prize for Construc- (Part II) By J. H. Barron, Jr. 16 tors-An Announcement 46 Radio Programs to Suit the Thermometer Radio Wrinkles 47 By V. Showell 17 Julia A Simple Remote -Control Device The Listener Speaks By Himself 18 By William F. Crosby 48 13roadcastatics 19 Interstage Coupling for Screen -Grid 'Pubes Television-Practical Demonstrations Over By E. H. Rietzke and N. M. Cooke 50 WR NY By Theodore H. Nakken 20 Methods of Obtaining Suitable Screen -Grid Vacuum Cameras to Speed Up Television Voltage By H. A. Pelton 51 By R. P. Clarkson 22 Letters from Home Radio Constructors 52 Radio Aerials By Fred H. Canfield 2i Radiotics 54

list of Broadcast Station Calls 28 I Want to Know By C. W. Palmer .55 How the Radio Public is Being Fooled 29 RAnIo NEWS LABORATORIES 58 Radio Aerials Create No Lightning Hazard On the Short Waves 59 By Baron Manfred von Ardenne 30 Experiments with a Double -Ground Sys- What is the Life of a Fixed Condenser? :32 tem +sa By W. H. Griffith, M.D. 74

RADIO NEWS is pnbllsbed on the 10th of each preceding month. There are 12 obtained from the publishers. Copyrighted in Germany. Reproduction of articles numbers per year. Subscription price is $2.50 a year in U. S. and possessions. is Germany is reserved for Radio, Berlin 92. Canada and foreign countries, $3.00 per year. U. S. Coin as well as U. S. Stamps IADIO NEWS is for sate at a1: newsstands in the United States and Canada. accepted (no foreign coins or stampa). Single copies. 25 cents each. Checks and and at Brentano's, Ave. de L'Opera, Paris, France. European agents: S. J. Wise money orders should be drawn to order of EXPERIMENTER PUBLISHING Et Cie. 90 Place Verte, Antwerp. Belgium. CO., INC. HOW TO SUBSCRIBE FOR RADIO NEWS. Send your name, address and re- All communications and contributions mittance to Experimenter Publishing Co.. 230 Fifth Ave., New York. Mention to this journal should he addressed to name the Editor. RADIO NEWS, 230 Fifth Ave., New York, N. Y. Unaccepted contribu- of the magazine you are ordering. We al.o publish SCIENCE AND INVEN- tions cannot be returned TION, RADIO LISTENERS' GUIDE. AMAZING STORIES and FRENCH unless full postage has been included. All accepted con- HUMOR. tributions are paid for on publication. A special rate Is paid for novel experi- Write clearly. ments; good photographs accompanying them are highly desirable. Publishers are RATES AND TERMS. The subscription rate for RADIO NEWS is $2.50 per not responsible for loss of manuscripts, although every precaution is taken with year. (12 numbers). When remitting do so by cheek. money order. or registered such manuscripts, upon receipt thereof. letter if cash is enclosed. Avoid sending cash through the mall if possible. Sub- scriptions for less than one year are not accepted. Subscription may be made in RADIO NEWS. Monthly. Entered as second-class matter, July 12. 1929, at the combination with SCIENCE & INVENTION, RADIO LISTENERS' GUIDE, Post Office at New York, N. Y.. under the Act of March 3, 1879. Additional entry AMAZING STORIES and FRENCH HUMOR. at Dunellen, N. J. and San Francisco. Calif. Title registered U. S. Patent Office, POSTAGE. We in all parts of the United Copyright, 1928, prepay postage States. Mexico and by The Experimenter Publishing Co.. Inc.. 230 Fifth Ace.. Island possessions. For foreign or Canadian subscriptions we require 50 cents in New York. The contents of this magazine are copyrighted and must not be addition to the price for reisrodneed subscription additional postage charge. in the United States without eking full credit to the publication. CHANGE OF ADDRESS. Notify us as far in advance as possible. It requires Translation into foreign languages must not he made unless permission is several weeks to make an address change on our records. Always write clearly. The contents of R.ADIO NEWS are Indexed In the Industrial Arts Index. copies of which can he found in every library.

Published by Experimenter Publishing Company, Inc. H. GERNSBACK, President S. GERNSBACK. Treasurer C. E. ROSENFELT, Secretary Member: Audit Bureau of Circulations Radio Magazine Publishers Association Editorial and General Offices 230 Fifth Avenue, New York City Advertising Representatives: RHODES & LEISENRING New York Offices: 624 Graybar Building Chicago Offices: 307 North Michigan Ave

www.americanradiohistory.com Radio News for July, 1928 3

+ topiitu/iaiiAeriu/s' 'p LTENNA *tailed blIndenfowd) NeedsNo Repairs REDUCES STATIC Girds Louder, Clearer DX No need to climb that roof again- except to take down the aerial that disfigures your home. The amazing invention of the SUB - ANTENNA puts that clutter of sticks and wires in the discard. Risk and annoyance saved -and a better, louder, clearer tone. Proof mid -summer or during storms. from Users Static reduced even in "I tune in WEAF with Sub - Uses STATICFREE Ground Waves antenna and actually have The of the wonderful volume and clarity of tones obtained to turn down my volume secret control almost to a quarter with Subantenna lies in the fact that it is installed underground. away from "OFF." When The same broadcast waves travel through the ground as through I switch to the aerial. I can contain less static and are affected less by disturbing hear scarcely a sound." the air but N. C. S.. New Jersey. noises. Subantenna receives these ground waves and transmits every note pure and audible. Even sounds from far distant sta- "Static has been entirely as clear as those from locals heard over the aerial. eliminated so far as I am tions seem able to observe. For clarity Thousands of tests made by users everywhere comparing Sub - and for selectivity the Sub - with the aerial have established the superiority of this antenna is the best device antenna I have ever had any experi- amazing underground device beyond question -and on our free ence with." R.L.P., Illinois. trial offer, you can have the privilege of making your own test our risk. "Last evening I got station on your own set at KFI at Los Angeles which came loud and clear on the Removes Lightning Danger Subantenna. Changed to outdoor aerial and could not Subantenna not only gives better selectivity and stronger tones, get this station but safety from accidenta possible on a steep or slippery roof and from R. IT. New York. lightning. An aerial can carry a lightning bolt into the house. With the Subantenna. the current would go into the ground. "Am located on car line with 8 transformers across street and high power wires Use It With Any Type of Set nearby. Aerial brings in dis- you have, Sub - tance with continuous roar. No matter what type or make of set antenna will work perfectly with it. And it takes only about Subantenna gets Loa Ange- aerial troubles and your roof los and Charlotte, N. C. Installed in 6 minutes to install it. Then your practically coast to coast se-- climbing are over. for Subantenna, sealed in a permanent con- lectivity. Clear bell -like tainer, needs no attention, no repairs. P.. Texas. Minutes tones." W. J. 5

Try Subantenna at our risk. Install it and make comparison with the other. Do this under the most MFG. CO. aerial by switching from one to CLOVERLEAF trying conditions. If you don't find that Subantenna gives greater 2714P Canal Street, Chicago clarity the test is free. Obtain a Sub- Tell me all about SUBANTENNA, your unqualified guarantee I distance, volume, loudness and and FREE TRIAL OFFER. I antenna from your dealer, or send the coupon for complete scientific explanation of Subantenna and particulars of our Free Trial Offer. ! Name

Address . Cloverleaf Mfg. Company i 2714P Canal Street Chicago, Illinois `iRei !MN awl OM woo 10MeiMN Ow wen mom ass Nam Cma Mil al11

www.americanradiohistory.com 4 Radio News for July, 1928 INDEX TO ADVERTISERS

Page Page Page A Page D L S Abox Company, The...... Back Cover Deutschmann Co., Tobe 83 Lacey & Lacey 71 Scott Transformer Co 71 Accusti -Cone, Inc. 86 Leutz, Inc., C. R 96 See Jay Battery Co 85 Acme Wire Company 89 E Smith, B. Hawley 73 Aero Products, Inc 89 Southern Toy Co 95 Aerovox Wireless Corp 86 Elba Products Mfg. Co 83 M Starrett Mfg. Co 95 All Radio 83 Electrad, Inc. 81 Co M. & H. Electric Specialty Co 73 Sporting Goods Co 95 Aluminum Company of America 63 Massachusetts Radio Electro- Chemical Company of and Tele- T American Mechanical Labs 79 graph School .. 85 America 83 American Sales Company...... 88 Midwest Radio Corp'n 72 Telephone Maintenance Co...... 72 Excello Products Corp 95 American Transformer Co 93 Muter Co., Leslie F 71 Teleplex Company 85 Amrad Corporation, The 87 Thordarson Electric Mfg. Co 61 Arcturus Radio Co 91 F Tower Mfg. Corp...... 87 N Townsend Labs. Fanspeaker Radio Co 73 71 National Radio Transformer Corp. B Fansteel Products, Inc 79 Institute 5 of America 72 Norden -Hauck, Inc. 73 Tyrman Electric Corgi 93 Barawik Co., The 78.93.95 Formica Insulation Co 79 Bureau of Inventiv Science...... 72 Fort Shelby Hotel 78 Freshman Co., Inc., Chas...... 71 o II C Outdoor Enterprise Co 81 Underground Aerial Systems 69 O Underground Antenna Co. C. E. Mfg. Co., Inc 75 Inside Back Cover Radio Carborundum Company, The 71 General Co 71 P Carls, M. J 86 Gernsback, S. 76 Pilot Electric Mfg. Co., W Carter Radio Co 78 Inc...... 4 Press Guild, Inc 82 Central Radio Labs 85 H \\Talker Co., The Geo. W...... 72 \Vestern Radio Mfg. Co...... 72 Chemical Institute of New York, Hammarlund Mfg. Co 81 Inc. 67 Wirt Company 87 Hamilton -Carr Radio Corp 79 R Chicago Radio Apparatus Co 69 World Battery Co. 78 Cloverleaf Mfg. Co 3 R. E. L. Laboratories 69 Consrad Co., Inc., The I Radiali Co. 73 64- 70- 74 -80 -88 Illinois Transformer Co...... 85 Radio Association of America 7 X Consumers Radio Co 72 Independent Electric Works 79 Radio Equipment Co 81 X -L Radio Labs 87 Craftsman Radio Products 89 Radio Instittute of America 77 Cunningham, Inc., E. T. Radio Map Company 87 Inside Front Cover J Radio Specialty Co 65 Y Curtan Mfg. Co 6 J.M.P. Mfg. Co. 72 Raytheon Mfg. Company 83 Yaxley Mfg. Co 93 ''PI LOT brings the latest in a4anu9 Í'ILOTRIRFLal:T1110. .p,a., 1 RADIO within the "PILOTS reach of alá! °FLYI AV LAO" RESEARCH laboratory surpassed G by few, manned by engineers who've Equipped with Pilot Short -Wave A Radio Apparatus,the Pilot Airplane grown up in radio, backed by a factory Radio Laboratory will be the first with unexcelled mechanical equipment airplane radio station to communi- -these are a few of the reasons for Pilot cate with amateur experimenters. quality, Pilot precision and Pilot engin- This is the Pilot Company's contri- eering leadership. bution to the development of a com- munication system which promises Volume production to be a great aid to the safety of air permits manufac- travel, enabling pilots to receive turing economies which are reflected in weather reports, fog and storm the popular prices of all Pilot Radio Parts. warnings while flying. SEND 4c. STAMP FOR CATALOG C. '-- ONE OF THE SET OF FIVE PILOT SHORT WAVE PLUG INS ÉI LOT RADIO PARTS ARE SOLD /V i IRA®IÓS Dl GGEST I keitY CI YI `IzED COI 11V r 25i VALUE! /INTRY THE NORIO. "RADIO DESIGN," a Quarterly Magazine edited by M. B. Sleeper, national radio authority, is brimming over with the newest and latest Short Wave, A. C. Data, Power Amplification, latest Television Development, etc. Send 25c. stamps or coin for four meaty quarterly issues. ILOT Name...... ELECTRIC Address TRADE R 323 BERRY ST..BROOKLYN.N.Y.

www.americanradiohistory.com Radio News for July, 1928 5

If all the Radio sets l'ce "fooled" with in my time were piled on top of each other, they'd reach about halfway to Alar,. The trouble with The was that I thought I knew Jo much about Radio that 1 redly didn't knot, the first thing. I thought Radio was a plaything -that was all 1 could see in it for me.

I Thought Radio Was a plaything But Now My Eyes Are Opened, And I'm Making Over $100 a Week!

I'd usually stayed home in the evenings after day I sent for their eye -opening book, $50 a week! Man alive, just one year never had a chance!" would have been the work, because I didn't make enough money been wailing "I ago a salary that big Now I'm making, as I told you before, of my ambition. to go out very much. And generally during height a little with Radio over $100 a week. And I know the future Twelve months ago I was scrimping the evening I'd tinker - of the my own or some friend's. I even holds even more, for Radio is one along on starvation wages, just barely mak- a set of fastest -growing busi- was the same old made a little spare change this way, which most progressive, ing both ends meet. It nesses in the world today. And it's work job, a salary just as small as helped a lot, but I didn't know enough to story-a little I like -work a man can get interested I myself had been dragging go very far with such work. that the job -while idea that a splendid Radio in. along in the rut so long I couldn't see over And as for the not be as bad job might be mine, if I made a little effort Here's a real tip. You may the sides. as I was. But think it over-are you me a year ago that in twelve to prepare for it-such an idea never en- off If you'd told a friend suggested satisfied? Are you making enough money, months' time I would be making $100 and tered my mind. When sign a me one ago, I laughed at him. at work that you like? Would you more every week in the Radio business - it to year now for the kidding me," I said. contract to stay where you are whew! I know Id have thought you were "You're the same money? money I'm "I'm not," he replied. "Take a look at next ten years -making crazy. But that's the sort of If not, you'd better be doing something pulling down right now -and in the future this ad." He pointed to a page ad in a magazine, about it instead of drifting. I expect even more. Why only today- new Radio game is a live -wire field of my story. I an advertisement I'd seen many times but This But I'm getting ahead never of golden rewards. The work, in any of hard up a year ago because I was kid- just passed up without thinking, was it applied to me. This time I read the 20 different lines of Radio, is fascinat ding myself, that's all -not because I had dreaming paid. The National holding then the the ad carefully. It told of many big op- ing, absorbing, well to be. I could have been in Radio Institute -oldest and largest Radio sort of job I'm holding now, if I'd portunities for trained men to succeed same field. With the adver- home -study school in the world -will train only been wise to myself. If you've fooled the great new Radio home to tisement was a coupon offering a big free you inexpensively in your own around with Radio, but never thought of it Z and to increase in just book full of information. I sent the coupon know Radio from A to as a serious business, maybe you're your earnings in the Radio field. boat I was. If so, you'll want to in, and in a few days received a handsome the same two colors, telling Take another tip-No matter what your read how my eyes were opened for me. 64-page book, printed in or how little all about the opportunities in the Radio plans are, no matter how much Radio -clip the coupon be- first became the rage, field, and how a man can prepare quickly you know about When broadcasting low and look their free book over. It is ago, I first began my dabbling and easily at home to take advantage of several years Well, it was a revela- filled with interesting facts, figures, and with the new art of Radio. I was "nuts" these opportunities. will you me. I read the book carefully, and photos, and the information it give about the subject, like many thousands of tion to of anybody's time. no when I finished it I made my decision. is worth a few minutes other fellows all over the country. And yourself under no obligation There's a fascination -something What's happened in the twelve months You will place wonder! that day, as I've already told you, -the book is free, and is gladly sent to any- that grabs hold of a fellow -about twirling since know about Radio. Just listening to a seems almost like a dream to me now. For one who wants to a little knob and suddenly had address J. E. Smith, President National Ra- a thousand miles away! ten of those twelve months, I've a voice speaking own. At first, of dio Institute, Dept 7S, Washington, D. C. Twirling it a little more and listening to Radio business of my dots and dashes of steamers course, I started it as a little proposition on EMI MEN the mysterious of National Even today I get a thrill from the side, under the guidance the E. SMITH, President, far at sea. gave me my J. this strange force. In those days, many Radio Institute, the outfit that National Radio Institute, It wasn't long before I I Dept. 7S, Washington, D. C. times I stayed up almost the whole night Radio training. much to do in the Radio line I Dear Mr. Smith: DX. Many times I missed sup- was getting so 64 -page free book, trying for little clerical job, and Please send me your per because I couldn't be dragged away that I quit my measly printed in two colors, giving all information my full time to my Radio business. in Radio and how I I from the latest circuit I was trying out. devoted about the opportunities take Since that time I've gone right on up, can learn quickly and easily at home to I never seemed to get very far with it, I understand this request guidance of my advantage of them. no I used to read the Radio maga- always under the watchful places me under no obligation, and that though. Radio Institute. zines and occasionally a Radio book, but I friends at the National I salesman will call on me. have given me just as much never understood the subject very clearly, They would Name see through at all. help, too, if I had wanted to follow some and lots of things I didn't my own a dabbler other line of Radio besides building I Address So, up to a year ago, I was just man- -I thought Radio was a plaything. I never retail business -such as broadcasting, enormous, fast -growing ufacturing, experimenting, sea operating, ITown realized what an they pre- industry Radio had come to be- employing or any one of the score of lines Occupation that until that J thousands ind thousands of trained men. I pare you for. And to think

www.americanradiohistory.com E Radio News for July, 1928 Get Winter Reception in Summer with Astounding Successful GROUND ANTENNA Clearer Ground Wave Reception Allows Greater Distance

Hundreds of satisfied users of the sensational Ground Antenna -Aer -O- Liminator -are wondering how they ever got along without it. All over the country radio owners are finding marvelous satis- faction in freedom from static and noise interference. This revolutionary improvement of reception comes from hooking your receiver to Ground Wave Reception. Radio engineers broadcast tell you that the J wave through the ground is in most cases almost static -free, and with rare exc eption carries Read Proof! no noise interference.

"I have tested anti thoroughly approve Natural Tone Better Selectivity the Aer -O- Liminator. I find It increases - selectivity and volume without distor- The rapidly increasing army of Aer -O- Liminator tion. practically eliminates static, gives owners also enjoy and good. clear tones, both on local and appreciate the natural human tone and clarity of this Ground Wave distant stations. Reception. If you haven't tried it you can't imagine the difference! I would recommend the use of Aer-O- Liminator to every ra,dlo owner Another advantage users have found with Aer -O- Liminator is the to get the best reception from his set." surprising DX they get. Distant stations formerly drowned out by static JOHN E. CHRISTENSEN or noise interference (Radio Engineer.) of air waves now come in clear as a bell. Selectivity is improved because, with pure, clear Ground Wave Reception, you can pick up and log signals that before were lost in the jumble of shrieks and howls so -There's no such thing as static common in DX reception through air waves. trouble since I got my Aer -O- Liminator. You shouldn't deprive yourself of the new thrill of pure, clear ground I get stations I never got before-Bo wave loud and clear I would almost swear reception a day longer than necessary. We let you prove it for yourself. they were in the next room." R. CURTIS, Illinois. FREE TRIAL Make This Thrilling Test At Our Risk ! Install an Aer -O- Liminator (Ground Antenna). Leave your old overhead aerial up. Try out on a night when static is bad. If you do not get a wonderful improvement in freedom from static, greater selectivity and clear, sweet tone without interfering noises, if you can't get good recep- tions on stations are that drowned out by static on your roof aerial, you - EASY -TO INSTALL need not pay us a red cent for this test! Send coupon at once for scientific Just dig a smi11 hole explanation of Aer -O- Liminator (Ground about 6 inches in diam- Antenna), proof of performance, eter and drop Aer -O- and our conclusive iron -bound guarantee and remarkable Free Trial Linlirn'or Offer -Mail Coupon TODAY!

Rush ThisImportanteoupoji AerO-Liminatôr CURTAN MFG. COMPANY, (Ground Antenna) 154 E. Erie St., Dept. 827-K.A., Chicago, III. Please send me at once complete description of Passed by the National Board of Fire Underwriters. Meets AerüLiminator, with details of guarantee,Sclentiflc Proof, and Free Trial Offer. requirements of the National Electrical Code. Endorsed Name by Foremost Engineers and Dealers. Address City CURTAN MFG. COMPANY State t ( Dept. 827 -K.A. 154 East Erie MO MN MN NM i St. Chicago, Ill.

www.americanradiohistory.com

_ ._. o G ernstac PublIshe-r

Editorial and General Offices, 230 Fifth Avenue, New York 1928 No. 1 Vol. 10 JULY,

SEPTF.MB1R'190_,..,,,,,.,,,..,__.,.,.,,.,,,,,,,,,,,, ._.,-,_"-_ No. 3 Vol. 3 RADIO CONCERTS N June Isth of this year the Daily Mail of worth -while novelty! While, of course, there is London inaugurated the first "world" nothing new about "canning" radio telegraph concert, in conjunction with the famous messages, the idea of catching the voice of a great opera star, Madame Nellie Melba, trans- opera singer by radio on a phonographic disc mitting her voice over vast distances; the seems rather novel and presents great possibilities. music in some instances was heard over a thousand The point we want to make here is that, altho miles away from the sending station. Madame America is supposed to be a country bordering Melba was performing at Chelmsford, near Lon- close to the radio milennium, and, altho there are is with don, singing into the microphone of a standard practically no restrictions and the law all radio telephone apparatus. the amateurs, progress, as far as radio telephony There was nothing'radically. new employed in is concerned, is negligible. sending out her voice, the apparatus used being In Europe, where the restrictions are very well known. and similar to what has been described severe, and where special authorization for such time and again in this publication. The voice, an experiment as the above -described orie must be on the other hand, was heard over a great expanse had, it seems the art is thriving even more vigor- of space wherever there was a radio receiving ously than here, where there are no such restric- station within range which had suitable apparatus tions. In other words, real enterprise, as far as for the interception of the concert, which, by the radio telephony and radio concerts, etc., is con- way, started at seven o'clock in the evening,.Lon- cerned, is rather frail and spasmodic here. Of don time. The results left nothing to be desired. course, there are many radiophone sets in the As a matter of fact; the several voices came thru United States now, and these are growing all the excellently. time, but there are very few big "stunts" that come First a deep voice slowly announced the pro- to one's notice, as, for instance, the one of Madame gram, then came the first strains from the piano, Melba described above. and finally the clear voice of the noted singer. There is nothing that popularizes radio more Several selections were rendered by Madame than a concert by a famous singer, and it is to be Melba, and the concert terminated with the Bri- hoped that our amateurs, as well as professionals, tish national anthem, "God Save the King." shall band .together and try for some original At Paris, the Societé Française Radio Flec- ideas. We wish to suggest here only a few: trique, on the other hand, took elaborate, precau- Why cannot someone go after the Presidential tions to receive the music in a totally unlike candidates and invite them to make a speech via manner than has ever been accomplisht before. radio thru a powerful telephone apparatus in the This company, with its headquarters at Levallois, near future? With proper advertising and with near Paris, erected a special booth, where by the proper enterprise behind such a scheme, it means of elaborate tuning apparatus, as well as certainly should not cost a great deal to do. The vacuum tubes irr great profusion, Madame people of the United States, thru the amateurs, Melba's voice was received and demonstrated to would get a chance to listen to our candidates in a large audience by means of a big aluminum a very novel manner. Another idea, which, of horn. The experiments, however, did not by any course, is not new, would be to transmit band con- means end there. The climax came -and here is certs from famous bandmasters broadcast. Such where the novelty comes in -when the Societé concerts could be sent from some of the big used a special apparatus comprised of nine centers, such as New York, Chicago, or perhaps vacuum tubes with which to receive the music. Atlantic City, or some other points where the It is interesting to note that, altho no antenna or bands are staying at the time. not alone even a loop antenna was, used, the music Of course, there are countless schemes and ideas of several hundred was received over the distance of a similar nature, all of which make it possible miles, but was actually registered upon a master radio, and that is what we are after. master, actual to popularize phonograph disc! From this Now, why don't we get together and do itt? discs were afterwards made, and all ' phonograph et GERNSB o of them were quite clear. Here, indeed, is a that was, of course, at that time no broadcasting as we know it today. It is believed HE above editorial appeared eight years ago in RADIO NEWS. There recalled the editorial urged us to proposal was made to broadcast speeches of Presidential candidates. An old reader who, Tthis was the first time the makes curious reading. reprint it; to which request we accede herewith. After eight years, the old editorial certainly

meters) and 2XAL (30.91 meters) on various radio and scientific subjects. Mr. Hugo Gernsback speaks every Tuesday at 9.30 P. M. from Stations WRNY (326 7

www.americanradiohistory.com Radio News for July, 1928 "Sure, Them Was RAD/0 S Cents ' the /`r1 AT E V t. JULY Happy Days" 19 19 Edited by E N. C'ierrlsback

A Gentle Debunking of the Yarns Which Old-Timers Tell About an Imaginary Golden Age of Radio By Charles Magee Adams

WHF.NEV>;lt old -time fans fore- gather to swap DX yarns, argue w u u 111..unnO.n...... p...... Oly, over the new circuits, or do any of the other things fans find so This reproduction of the supremely worth while, cover of the first num- the talk scarcely ber of RADIO NEWS gets well under way before sonie graybeard shows how most radio interrupts the proceedings to unburden him- fans of the early days did their listening: with self about as 'fbilows: telephone receivers on "But listen belligerently- "you've got their heads and upheld -" hands requesting silence. to remember reception's nothing like it used The receiving set shows to be. Why, back in the old clays when I consists of a loose -cou- pler, with tapped pri-

was . still using a one -tube blooper" -edging mary and secondary, two IN l !ìl.S ,kir NYE, i7ir As. forward on his variable condensers and Ón:c.a"a,".:+ chair -"I used to get the ISS L . gsRPRtMEnizs one vacuum tube. l: West coast regular. KFI, KHJ, KPO, all of 'em -I could sit down any old night and bring 'em in, and 1 mean right, too. You know l'm not lying. The rest of you used to do the same thing. And what do we get now ?" registering disgust. nunciation of the present; adjourning only son- -and with all due respect to their ve- "Why, with that new seven -tube job, when the assembled delegates resolve to go hement statements old- timers that's as slick as anything -the tend to I ever had my home and once more write Washington, de- remember only the good reception of radio's hands on, I've got KFI just once! "- regis- manding a return of radio's golden age. happy days, and to forget the reception that tering greater disgust- "And I don't have How much of all this is traceable to the was indifferent or worse. Reference to to tell you why. It's super-power. It may mellowing mirage of memory, and how much accurate logs would demonstrate be all right that bring- for these program hounds; but to fact? 'l'he answer is about fifty -fifty. ing in the West coast was nowhere if you real near as want reception I say they regular a feat, four live GOOD "FORGETTORIES" or years ago, as oughtn't to let any station use more than a some would have thousand watts. us believe, and also the That's all any of 'em had Through it psychological law that makes stations were nowheres near as good when in the old days, and all of you know how sanity possible for most of us, the mind received -of which more presently. This much better reception was then." has the trick of keeping pleasant experiences much for the tricks memory plays on the Fired by this keynote speech, the con- in the foreground of memory and relegating "detector grid" the vention forthwith of mind. launches into rosy reminis- the unpleasant to the background, when they As to the facts, it is true that reception cences of the splendid past and scathing de- do not fade out altogether. For this rca- "ain't what it used to be," but -and here

111111i1n1;lluininli,nmam%

"Whenhen I was still using a one-tube blooper, I used to get the West coast regular. With that new seven - tube job, that's as slick as anything I ever had my hands on I've got KFI just once!"

www.americanradiohistory.com Kadin News for July, 1928 9

s the detail generally overlooked in the old - geographical and in the frequency band, issue between headphones (not "earphones", timers' conventions -for reasons as much this spreading could be minimized. But for the love of microfarad!) and loud Lpparent as actual. First, regarding the such a separation has not been incorporated speakers. actual. in the present allocation setup; with the Whenever a disgruntled old -timer re- The writer (who is an old -timer himself, result that many DX stations for which fans counts his past achievements in getting the and therefore sympathizes fully with fellow shoot are blanketed out of audibility by coast with one or two tubes, it will be noted members of the great fraternity in the evil other stations 10 or 20 k. c. away. that he used phones, and, even when he used days which have descended upon them) used This for the physical factors involved. as many as four or five tubes, cross -exam- to bring in KHJ and KPO (then 500 -wat- Now to return to the psychological. ination will divulge the fact that he gen- ters, and 2,200 miles away) back in '23 with erally plugged in the headset for DX. reasonable regularity, using a single -tube ANYTHING WAS GOOD ENOUGH These days scarcely one receiver in a hun- dred is equipped with a phone jack, and blooper of very dubious vintage, with only a realize Even the incurable old -timers must lies much of the prevailing grief lamp- socket aerial. In contrast to that, demanded, therein that a standard of reception is about the absence of DX. during.the past winter, using a modern six - times higher than four or hie today, many With all due respect to the many fine tube receiver, he has been able to ensnare years ago. Back in the "good old days" KFI -now a 5,000 -watter-only infrequently loud speakers on the market, it is no secret getting a station meant simply being able to them are nowheres near as from southern Ohio, and rarely with what inter- that the best of pick out its call letters. If static or sensitive, to feeble signals, as an average could be called real volume. But unlike made neces- ference from another station it pair of headphones. They simply cannot be many brother fans, he does not charge this four or five announce- sary to wait through so, yet handle the large volume they are lamentable reversal of form solely to super- ments before even that could be done, and power; instead, he takes account of a called upon to deliver during normal opera- the volume was so feeble that the listener tion. a signal which would be audible narked change in the physical conditions -speaker So had to thrust his head into the loud with phones on the detector or first audio, affecting reception which has come about no difference. Little was horn, that made just cannot be amplified sufficiently, even during the last five years. then. But these days expected of radio by high -power boosting stages, to the point listeners have been educated to demand where it will actuate a loud speaker de- OLD SOL, THE CRIMINAL and that the West coast come in as clearly signed first of all to deliver large volume of cleanly as a station 500 miles away; with the good quality. If the apostles of gloom who It has been established, by no less au- when it result that they grumble loudly complain so loudly of poor DX would go thorities than the Bureau of Standards' does not. physicists, that sunspot activity exerts an back to phones, they would make the dis- This is particularly true on the score of concerting discovery that, barring the in- adverse influence on radio reception of volume. When a three -tube blooper was primary importance. (See also the leading terference mentioned, distance reception is an aristocrat among receivers, bare audi- much better than four or five years ago; for editorial in RADIO NEWS, June, 192G issue, bility was all anyone asked of DX. But in "Summer Radio Reception" on the same the very reason that transmitter power has these days of six -or- more -tube sets, incor- where can subject, and that of SCIENCE AND INVEN- been increased to the point it porating power amplification at the audio now overcome normal static. TION for August, 1926, "Sun Spots and end, the fan does not consider that he has Radio") Studies have shown that during '22 So it turns out that neither is the dismal really "got" a station unless it roars in present of DX reception as dismal nor the and '23 -the happy days to which old- timers loud enough for his neighbors, too, to hear. refer so wistfully- sunspot activity was at a golden past as golden as some of the old - The psychological result is that he has lost timers would have us believe; and, in par- minimum, while today it is at a maximum. his fine acuteness of hearing for weak sig- The eruptions on the sun's surface, it has ticular, that super -power is far from the nals. Accustomed regularly to volume that piece. also been shown, occur in cycles of 11 years, double -dyed villain of the fills the house, he misses the feeble call Not that all this is anything new, of which will bring another period of "opti- back- letters that barely override the noise course. Twas ever thus, long before the mum" (best) conditions in 1933. So it ground, when five years ago he had trained develops that Old Sol is the real master first disaster of 90 volts across a filament. his hearing to such a fitness that he could With chronic discontent, man has ever criminal responsible for the present poor have picked them out with no difficulty. DX. turned his eyes to the past and said, "'l'hem however, does not mean that super- was the happy days." Ofttimes they were, This, HEADPHONES VS. LOUD SPEAKERS power wins a complete acquittal. Notwith- to be sure. But in the case of DX as she standing the statements of some broadcast But the most important point in this is received today, an examination of the engineers, most fans know from bitter ex- whole jeremiad about poor reception is the facts reveals rather a different story. perience that, save with receivers of razor - edge selectivity (many of which slice off the sidebands) a 5,000- or 50,000-watt station spreads more than a 500- or 1,000 -watt transmitter. Given wide separation, both

.4 few years ago a man was satisfied if he could get a station's call-letters by sticking his head in- side the loud speaker. To- day he expects the speaker to blow out the an- nouncer's voice like a hur- ricane.

www.americanradiohistory.com 10 Radio News for July, 1928

THE greatest step for the betterment Many of these sets are so small that they cinnati, or W'l'.1J1, Cleveland, it is possible of conditions in our American can be easily placed in a cigar box. Others to hear excellent programs most of the time. prisons is directly due to the influ- are placed on a small shelf or on the floor; A few prisoners, more fortunate than the ence of radio. Radio bas clone more for be it known, the small "drums" we call rest, own powerful eight- and ten -tube sets, to enlighten, instruct, and create a desire, home are no wider than the average coal- enabling them to get good programs from in the prisoner, to return to respectability chute. practically every station of importance in than all the legislation our assemblies can If one were to walk through the long, the country. WRNY, KFI, WJZ, KMOX, write into the books with the idea of dimin- cheerless corridors of the cell block, the first and many others are favorites that in- ishing crime. thing to attract the eye would be hundreds variably come in with sufficient volume and Jails and penitentiaries are made for of aerials stretched from the prisoners' clarity to satisfy the appetite of the most those who have little to lose, and fancy they cells to the wall of the hall some twenty - ardent radio fan. have much to gain, by crime. Were we to five or thirty feet away. With short aerials, Those whose knowledge of music had been open the question of comparative guilt be- nine or ten feet apart, it is to be expected confined to the chapel exercises and the tween sinners who are in bonds and sinners that there is considerable interference, noise annual minstrel shows, are now up in musi- whom the law cannot touch, this article and disturbance. Yet the men never com- cal events, including classical, semi- classical, would expand into a volume. We must plain. They do the best they can, and, un- sacred and popular music. And there isn't leave the inequalities of human justice to der favorable atmospheric conditions, tune a. late tune but they can whistle or hum, balance themselves, while we examine, in their favorite stations with ease. thanks to the radio. briefly, what radio is doing for prisoners Less than an hour ago, I heard one pris- "People don't realize the hours of happi- behind the cold, frowning ramparts of the oner say, "That little `box' may make a ness it brings us," one prisoner said, who Ohio Penitentiary. lot of racket; but it helps me while away was repairing his set. There are probably more radio sets in the the long hours, keeps my mind far removed "When one listens-in on the radio he must confines of the Ohio penitentiary than in an from my- imprisonment, my troubles, and concentrate his thoughts on his work. When equal area anywhere in the world. Just above all, it keeps me in touch with the I first came here we all dreaded the coining how ninny there arc, no one knows. Between outer world." of the night. It was from the prison work- 900 and 1,000 sets would be a conservative shop or the "idle house" to supper and then PROGRAMS ENJOYED estimate, and there are almost as ninny dif- ARE to our cells to be locked in for the night. ferent makes. The speaker, a hank robber, doing a long Completely shut off from the outside world. tern, is the proud possessor of a little one- we OLD -FASHIONED LISTENING Of course read, but orders are orders tube set. What he said goes for practically and the lights go out at 8.30. After that it Most of the sets are home -made. Prisoners every prisoner in this and every other was the solitude of our cells. Many nights lead up on radio and many have become prison in America. I laid awake until the wee hours of the experts in making good sets. In many Columbus, Cleveland, Cincinnati, New morning. Night was a horror then. Now it cells there are two pairs of head phones. In York and Chicago are the favorites, for is a pleasure." others a prisoner will separate his phones, they can he tuned in with little difficulty. That prisoner said a "mouthful." He was giving one to his cell -mate to hear the pro- With Columbia chain programs coming right. Now prisoners return to their re- gram coming in. No loud speakers are per- through WAIU, and the red and blue net spective cells after supper and find a world mitted in the prison, so all prisoners with work of the National Broadcasting com- of pleasure in tuning in various stations. radios have to use phones. pany coming either through WSAI, at Cin- 'l'he "lights out" hour is still 8.30; but

www.americanradiohistory.com Radio News for July, 1928 11

Warden Thomas still permits the men to too -don't you think she couldn't! But, their time, they plan for the evening's en- listen in on their radios as late as they wish, heck, we have heard the sanie tune a hun- tertainment, instead of brooding over their providing they do not go into hysterics over dred times, but it never affected Jim the troubles or planning some kind of deviltry. some "hot mama" strutting her stuff, or way it did this time. shout "bravo," when some opera star hits "Didn't know what the matter was until "HOME" SET BUILDERS 'stecn notes above the staff. the next morning when I asked Jim what In the prison library, conducted by was the matter with him the night before. Chaplain T. O. Reed, are many books and PRISON RADIO STARS Ile finally told me that the girl who sang magazines on radio, and the chaplain will was an old sweetheart, and would have told During the past few months we have tell you that they are in greater demand me more, but he started crying again and I heard President Coolidge, Governor Al than any other books or magazines in the walked away. Smith, Col. Lindbergh, Secretary Hoover The men read up on radio, and "We have neither of us mentioned the library. and other famous men. Still, in "this man's when an improvement can be made by matter since, but it was over a week before town," we don't all listen in. We have con- themselves to their radio set they make it. he would let me turn the set on again. tributed our mite to radio. The Ohio peni- The radio programs are clipped from the Jim's a funny fellow that way. But he's tentiary has clone much to furnish Central radio pages of magazines and newspapers, gotten over the tune now and we enjoy the Ohio radio stations with excellent talent and each man picks out his own program. set again. But do you know the never tunes to diversify their programs. Warden 1'. E. A guard who went through not long ago in Chicago any more ?" Thomas has repeatedly supplied prison checking up the stations that were being talent to stations WEAO, WAIU, WLW, heard, found that more than fifty stations and others. Incidentally, the talent is on BACK TO DIXIE were tuned in at the same time in different a par with that heard over leading mid - Colored prisoners as well as others have sections of the prison. western stations. This is best evidenced by done wonders the men be- their sets. Several negroes who migrated Radio has for the fact, that after each program in which north when they thought they could secure hind these massive walls of grey. It keeps the prisoners appear before the microphone, work and big wages, have their sets, and them in touch with the outside world as hundreds of letters and gifts for the en- invariably tune in Atlanta, Memphis, Chat- nothing else could do. Many who are un- tertainers pour into the prison post office. tanooga, Birmingham and other southern able to read or write enjoy the programs To be sure, some reformers started a pris- stations. Some prisoners prefer KWKH just as much as the better- educated series of howls that reverberated from one at Shreveport, La. That is the station whose oners. Ignorance is no bar to enjoyment end of the state to the other, but their owner is always in a fighting mood and of radio. efforts availed them little, if anything. To ready to jump anybody, anywhere, anytime. Each clay new sets are being added to illustrate just bow much some of these peniten- We love a fighter and that guy Henderson those already owned in the Ohio "would -be" reformers really know about set installed there is is sure a champ'. Whenever we can get iary ; and with each prisons and prisoners, I will relate a little Shreveport, we never worry about what the making of a better prisoner, a future incident that occurred last Sunday. We in we are missing. citizen who will be an asset to the state were in our cells; and a party of visitors Warden Thomas does not object to the lieu of a liability. were being escorted through one of the cor- was ever men having their radio sets. He will tell If no further benefit from radio ridors. us you that they improve the morale of the received than that which it furnishes to "Why, officer," exclaimed one, her eyes men. "When they are listening in on their unfortunate men, it is the greatest God- as big as saucers, "they have aerials and radio sets," said the Warden, "they are not send in the world. Transplant a man from radios in here!" hatching plots to escape or make trouble. the outside world of hustle and strife, put "Yes, ma'am," replied an "egg" on an this or And the worst punishment I can inflict upon him behind the cold grey walls of upper tier. "An' sonic of us even got ears only an unruly prisoner is to take away his any other prison, with the association and brains !" radio set." of others who have fallen by the wayside In our search for entertainment we have The boys with the radio sets are better in the busy struggle of life, and, to say the many interesting experiences. It is not un- behaved. They give better work in the least, it does not go to make a better man usual for a prisoner to want to hear the shops, and in the "idlehouse," now, where of him. He soon learns to despise society, broadcast station from his home town, if hundreds of them must of necessity spend (Continued on page 80) there is one there. This was the habit of a prisoner who formerly called Chicago his home. In his younger days he was a church member of a prominent Chicago church; he sang in the choir and his sweetheart was a member of the same organization. Just about the time he was to be married some- thing happened. He came to Ohio and again something happened. The young chap was arrested and today he is serving a "gang" of years. He always tuned in one of the Chicago stations when possible, in prefer- ence to all others. This was his habit until about a month ago, when the "something happened" again.

FROM HAPPIER DAYS "It was Sunday, and we were listening to an evening concert," his cell buddy said. "The music was coming in tine and Jim (that isn't his name, but will do in this case) seemed to get unusual pleasure out of each musical number. He knew most of the songs and joined in singing with a voice that was better than the singer at the other end in most cases. He certainly was a sweet - voiced tenor. "But all at once a woman began to sing `Dream Kisses.' .lino lowered his head and started to bawl like a kid. Darned if lie didn't cry for a long time, too. He shut the set off, and refused to let me operate it. I didn't know then what happened, but all night long Jim kept tossing and rolling in his bunk, and several times I heard him sob. When these steel doors shut upon a prisoner, he has one tie still binding him to the The dame who warbled could warble some, remainder of humanity-the faithful, tuneful, compassionate radio.

www.americanradiohistory.com 12 Radio News for July, 1928

Municipal fireboat being directed Microphone installed in fire -alarm from shore during test of radio box connected with shore radio equipment, © Photos by Herbert. transmitter to talk to fireboat.

Fire -alarm box which may soon be Radio equipment installed aboard replaced by new radio communica- the "John Purroy Mitchell" during cation system. demonstration.

www.americanradiohistory.com 13 Radio News for July, 1928 ter of considerable importance in dealing with a fire.

A RADIO SURVEY OF THE HARBOR Tests recently conducted by city officials have proved that the installation of radio equipment on the city's fleet of fireboats will increase the efficiency of that branch of the service to an enormous extent. Under the new plan, lire -alarm boxes along the waterfronts will be equipped with special telephone devices which will connect, over special lines, directly to the radio trans- mitting and receiving equipment. This will enable the person turning in the alarm to communicate directly with the captain of the fireboat, whatever her position, and in- form him of the exact location of the fire, In preparation for the first tests, a sur- vey of the harbor and rivers around New York was made by Isaac Brinberg, engineer in charge of WNYC, the municipal broad- cast station of the city of New York, under the direction of Robert Goldman, Commis- sioner of Plants and Structures, in order to ascertain the "field strength" of a trans- mitter located at the Municipal Building, and to determine just what types of equip- ment are best suited for use both ashore and aboard the boats. During a series of three tests it was found that there are no serious "dead spots" along any of the waters sur- rounding the city when a wavelength of 730 meters is used; although a decided de- crease in signal strength was noted when- ever the boat passed under any of the bridges spanning the Harlem and East lì ivers.

A GENUINE TEST For the purpose of the tests, a complete 200 -watt, C.W. and I.C.W., transmitter was installed aboard the fireboat John Purroy Mitchell, together with a sensitive vacuum - tube receiving set, while similar equipment was placed in the operating room of WNYC. was licensed under the call on The ship station here. letters WRBE. The aerialaasorecntlyebccncuoaaeflcd,laashshcn 1hÑewnork's historic City Hall. (Continued on page 73)

HE city of New York bas again found that radio can be used to in- crease the efficiency of its depart- T ments-this time aboard the city fire- boats. With a similar end in view, the Police Department recently installed an elaborate system of radio communication, including complete radio transmitting and receiving sets,- on the Macon, the city's official welcoming boat. In the past, one of the greatest difficulties in the handling of the fireboats has been caused by the lack of any means of com- munication when the boats are away from the wharf. Once beyond hailing distance of land, it has, in the past, been impossible for those directing operations to issue any further orders to the tugs until they again come near the shore or unless a special boat is used as a messenger. For example, sup- pose that a fireboat is near Spuyten Duyvil (at the upper end of Manhattan) and after putting out a fire there is wanted in the o upper end of the East River. If the boat is on her way down the North (I-Iudson) River to her home station at the Battery (at the southern end of the island) she with head- ¡4. will he completely out of touch quarters for approximately one hour. How- ever, with radio equipment aboard, it would be possible for her to be taken through the Harlem River almost directly to the scene Building, room and transmitter of WNYC, located on the 25th floor of the Municipal all around the The control station is owned and operated by of the fire, without going where the radio telephone and telegraph tests orininatcd. This island; thus saving about two hours, a mat- the city 4 Ncw York.

www.americanradiohistory.com 14 Radio News for July, 1928 Joie Passing of the Third Floor Quac 1 v oberi Francis Srniff.1

is SEE," remarks Doris, peeking over "Oh, yes," drawls Tap, "I rentember- girls are all about The Master. the top of a copy of Variety, "that "l'he Shepherd of the. Stills.'" "It's no use, kids," I calls, "Jerry's weak- the Siamese Twins are entering the "On the lam, movies." kid!" giggles Millicent. ness is radio." "Yeah," I replies, "they ex- "You're grounded pect to sign with and don't know it!" But they fusses around him until Harry United Artists." Tap grins, and comes Doris gives me the bird. over to watch us squawks for an ensemble number. The "Ixne ticking - perspire a new cre," she trick step. Somebody Master and I parks on a trut.tc to watch the advises. "Save that one for the switches off Lambs' Gambol." the radio and a howl goes up. ankles ank. I opens the pot. If you've never been behind the "Anything "I haven't the heart," I returns. asbestos on the w.k. mind ?" when ideas were being vented, you've never "Nothing whatsoever," "'Then get your circulation audited !" replies Jerry. "I've heard static in its native heath. All in all, not a care in the world, just at present." snaps. the frau. "Conic on -we're clue to we're hoof!" having a wonderful time, when The "It must be a novelty," I remarks. Master blows in. It's backstage during rehearsals "It is," agrees The Master solemnly. of My Out at Brightmere -on- the -Deep, The girls -Radio Girl, a hop, skip and flop fracas Long are lined up, two rows, ten to Island, where the gaseous nebula and I get a set, and Harry is telling them wherein the tenor saves the soprano from our -you need the mail, .Terry Lawson is our nearest no amplification on Harry -well, spin the baritone while thirty -two Rumpus Baby neighbor Stars go and closest pal. Inquiring at his dial off to Buffalo left center. These front door, - latter are the vital the butler will doubtless tell you "Lissen, you flock of beef toters, whassa element in musical com- that "The Master edies. As Aesop remarked, is in his laboratory." idea ... you ain't understudying no ocean Farmer Boys For Jerry is belong to a Calf a scientist, twenty-five, tall, liner ... I should provide you with tugs Club; City Boys do tcx,, dark and devoted but in a different way. to radio. Incidentally, ... I said bell, and I mean bell ... bell, he's a millionaire, which usually get me! No Consequently there are caties all is more doorbell, either ... like this over than an incident. high the places, blondes, brunettes and red -heads, ...... come on, snap into it . . . Most of the cast know The with the all distinguished by it Master -the music ... with the music! . . . common complaint - length of time it takes hu nger. Doris and a chorus girl to try now, sweet children, let us BELL-act like I (Mr. and Mrs. Joe her wiles on Hammerstein, thanks) dragged Jerry is equal to the distance you saw a mouse ... most of you dumb along our between 300 and 400 meters broads suitcase radio this morning, and everybody on the dial of couldn't act normal ... oh, f Gawd's a single -tube set -and he's always sake, in the outfit is trying to tune in all welcome, Muriel, that's right, fall all over the at once. having recently developed a flair piano, "Listen," commands Millicent, third from for ar- it won't mind ... yes, you're stiff, tistic lighting, and liking to come around all right, mostly the right, "cut out that hooey about bee in the head .. , now girls, and offer advice. That's his story. . . . farming and connect with the station that's please pretty please . . . beautiful broadcasting "Oh, hello, Jerry!" yelp about thirty please ... Elaine is that your the new play at the Regent." bowzers, making ... name "IVliat's a grand rush for the prize ... well, King Arthur wants you to the name of it ?" asks Tap .Tones. and bowling over bell "I don't recall a deck -hand en route. ... 'way up ... all right, all right, whadda -but it's about a federal "Wliadda ya think this agent." is- Country Store you want " night ?" demands ... the scene- shifter. But the Somebody tunes in a luncheon broadcast -it's noon- and runs up a few stages on the loud speaker. At the mention of food there's rapid dissension in the ranks. Harry throws up his arms in despair. "I give up ... finis ... the end ... go eat, and be hanged !" "Pleasant fellow," says Jerry. "Why do the girls tolerate it ?" I shrugs my shoulders. "You've gotta go through static before you can get distance, haven't you? These bimbos hope to be stars some day. This is merely tile listening in." "Apparently," answers The Master. The girls are attired in practice suits, and one of them, Elaine, previously men- tioned, passes us on her way to the dressing room. Jerry stops her. "You'll pardon me," he requests, "but don't you find this work a bit strenuous ?" Elaine is one of the quieter kids -a bru- nette with a kitchen complex -and of course she doesn't muff a chance to get chummy with the long green. "Oh, yes, I often tire," she answers, all eyes and figure. "But my doctor has been prescribing treatment, "fl'h!y, this thing and I find it most couldn't produce a shock," snorts Jerry. "Yet, I got one effective." from that chair belt!" "Indeed?" inquires The Master politely.

www.americanradiohistory.com Radio News for July, 1928 15

"Would yoti care to lunch with Doris, Joe radio waves -those that aren't being used meal spouts for Jerry's benefit. At two and myself ?" by sets -to stimulate the heart." we're back for more rehearsal. I gives a start, and ogles Jerry. It's "But I don't understand -" When Elaine comes out, dressed for prac- unusual for him to notice girls, and he did Elaine is seemingly annoyed. "I thought tice, she hands The Master her belt. It's of this all by himself. you knew all about radio," she pouts. "I light leather, about four inches wide by

"Oh, . I'll be delighted!" she squeals, and mean the Tolman Breast Belt. I'm wearing a quarter of an inch thick, and hooks in runs off to make a quick change before they one now." front. There's nothing noticeable on the closes the Ritz. "Tolman Breast Belt ?" reiterates Jerry, exterior. "I thought you were cured," I snorts. puzzled. "Never heard of it." "I'd like to purchase this, if I may," says "How come ?" "Why, it's the greatest invention of the Jerry. But Elaine shakes her head. The Master shakes his head. "Have no age!" she exclaims. "It's doing me a world "Oh, I couldn't be without it a moment," fear, Joe, I'll never fall in love again; once of good." She fusses in her bag and pro- she declares. "But, if you really need one, was entirely sufficient. This is mere curi- duces a small folder. Dr. Tolman will fit you for twenty -five osity." The Master scans it, and then hands it dollars." "Why Elaine?" to me with the office to keep mum. The Harry bellows for work, and we aren't "She seems a rather ingenuous young front page of the brochure is enough. It excused until four-thirty. The Master's been thing," he replies vaguely. states: studying the folder's claims in the mean- "Just a little Yellow Cab girl," I states. while, and beckons for me to join him. "Pick one up anywhere." "This might be interesting," he states. "Is she looking for a husband ?" "Would you care to help me follow it "Is she -say, Elaine's just aching to take Are You Tired, Worn Out, at the End down ?" some poor goof for petter or for hearse!" of Day? Lack Pep? Bave No Ambi- "Try to keep me away!" I defies. The Master lapses into a mood, and I tion? Then Be Fitted with the "Where's Tolman's hangout ?" don't destroy it until Elaine comes back, Marvel of Medical Science, Jerry reads off the address, and we glom all thrills and the mark of envy by the other DR. TOLMAN'S RADIO BREAST BELT a hack up to the joint. The neighborhood eye -fulls. Jerry brightens immediately, and Immense quantities of electricity, the is middle -class apartments; they don't park we out to tie most vital factor in life, are constantly in hydrants, when Doris joins us, wanders passing through the air since the com- any Rolls -Royces front of up with a salad. ing of radio broadcasting. DR. TOL- neither do they yell down dumb- waiters- We get a booth in a quiet cafe, and tin MAN'S RADIO BREAST BELT converts much. An office building on a corner dis- rag is forthwith masticated. This sorta these electrical waves into UNTOLD plays Dr. Tolman's sign from a third -floor ]:? ERGYI SPECIALLY VALUABLE IN leaves Elaine in the cold, being a stranger; CASES OF CHRONIC DISEASES OF window. but no chorus child ever let a chance at TIIE HEART. ` "l'here exists this difficulty," begins The big money go untouched, so she casts for big Master, and I see the campaign is on . "My fish with a play at Jerry's profession. photo has been given considerable publicity "Oh, are you a radio man, Mr. Lawson ?" of late, what with my weather control and she inquires naively. Just a gorgeous fake, but I sees that such, and I fear that anyone as clever as "Why, yes," replies The Master. "1 am a Jerry's got something to think about, so I Tolman must be will recognize me. Would radio engineer." stays silent while he pumps Elaine. you mind going up alone, first? I'll be "Among other things," I puts in, "includ- "Oh, yes, indeed, I recall it," he lies here in the drug store." ing A.B., S.B., Q.R.M., B.V.D., or what beautifully. "Dr. Tolman -oh, yes, of Entirely logical, because Jerry's got a have you ?" course. How long have you been using this hefty rep in scientific circles. He instructs Jerry sees it's a joke, and laughs. But belt ?" me as to the plot, and I gdes on up. Elaine sticks to her wavelength. "A month," replies Elaine, tickled at'hav- Tolman's offices are neat, but not gaudy; "My physician has been ordering radio ing got Jerry's attention. "I feel so much they look almost honest. A nurse that treatments," she says. "I find them so better -my heart beats are more even." should be in the Follies takes my card and much of a help." "When we return to the theatre, may I (Continued on page 66) "Radio treatments ?" repeats The Master, see the belt ?" asks The Master. "I've never surprised. "Is he broadcasting his advice ?" closely inspected one." "No, no," explains Elaine. "I mean the Elaine assents, and for the rest of the

"It's a lie!" shouts the doc. "I can prove that-" "Yes ?" drawla Jerry. "Will you take this teat chair out to my home?"

www.americanradiohistory.com 16 Radio Nc.cs for Jule, 1928 How Many Stations on One Wavelength?

Part II, of a Discussion of the Problem of Enabling More Than One Station to Operate on the Same Wavelength and Same Program

By J. H. Barron, Jr.

S SUMING that it were practical too ception while the chain program was on, a chain program on one could do so, happy in their knowledge that broadcast the mule issue of RADIO NEWS, Mr. a large number of IN they would tune in a station not on the wavelength from Barron discussed the practicability in various localities, the chain, and not waste precious moments tun- stations of "one program, one wave," which so by the listeners would be ing in a station just audible, waiting breath- benefits derived many of our readers hail as the remedy manifold; for those located near the broad- lessly for many minutes -only to discover . for broadcast congestion. Below -he dis- cast stations as well as those living at re- that this station is putting out the same cusses other important advantages program carried by the local station! mote points. may well be expected from this the bugbear of which The need for super -power broadcast sta- The effect of "fading," method. The problem of synchronize- distant reception, would be greatly reduced.' tions would be diminished. It would not be , as well.as program transmission is, location in the United Lion, necessary for one station to broadcast with At practically any however, one to tax the best of the en- least two stations 50 kilowatts to reach a listener already States, the waves from at gineering brains which are being ap- may be re- served by the clear reception of a number broadcasting the same program its solution. The amount of that fading would plied to of lower-powered stations. The super -power ceived. It is not likely technical skill and calculation involved take place equally from each station at the station could be changed to a 500 -watt sta- is beyond the imagination of most tion and spare the nearby listeners from the same time. When the transmission from However, we may from broadcast listeners. blanketing effect of which so many com- one was decreased in intensity, that confidence for remarkable im- or look with plain. the other would probably be normal provements in chain -broadcast tech- would cause a If the stations on a certain chain had stronger than usual. This nique in the next few years, just as we received at all times; previously occupied fifty different channels stronger signal to be have seen them in the past.-EDITOR. the more stations within .range of the re- when they broadcast on differing frequen- ceiver, the more consistent would be the cies, and were now operated simultaneously reception. on a single frequency, this would leave forty-nine channels for other broadcast in- Another annoyance, often caused by one would necessary for accordingly. It not be to use. This would provide the lis- station going off the air at the most in- which is terests him to "fish" around to see station tener with a great increase in the variety of teresting point of the program, would be coming in the best. He would leave the con- alleviated. if the local station to which one programs obtainable, certainly a desirable trols alone, after they were once adjusted, situation. usually listens should cease transmitting, the he the best re- knowing that was getting As there are (practically) only five chains listener would immediately hear the trans- ception possible at all times. mission from other

N i

www.americanradiohistory.com Radio News for July, 1928 17 Radio Programs to Suit the Thermometer

What is Being Done by Broadcasters to Dispel the Dog -Day Doldrums of the Radio Audience

By Julia V. Shawell

WHEN the thermometer rises and had come upon us was already deep in hot - audience in the months most dangerous to the last balmy breeze of late spring weather plans. the industry. has given way to listless, heat - IVOR and the Columbia chain stations Only the so- called "nuts" would be will- laden air, when energized activi- have decided that if their radio friends don't ing to swelter unnecessarily under the in- ties are suspended and the whole country find solace in what they pick up on the fluence of radio entertainment just for the is engaged in the difficult task of cooling dials, it won't be the fault of studio offi- joy of fooling around a receiver. But every itself, radio will offer a measure of relief. cials. And all the independent stations in fan will turn eagerly to a station which Already broadcast officials have planned New York, Cleveland, Detroit, Chicago and will send out cleverly -planned numbers to their summertime programs, designed pri- other centers of radio interest all over the make folks forget that the mercury is marily to frustrate the weather man and continent are just as absorbed and serious soaring. to make millions of listeners forget their in their purpose to send out entertainment temperature discomforts. Mental sugges- which will offset some of the havoc wrought IN TISE STUDIOS tion, in a more comprehensive manner than on otherwise pleasant dispositions by Before the listeners can be convinced was ever attempted on the ether, will be weather reports. that radio waves can carry them refreshing brought into use when July and August Several of the stations have already ar- material with which they may be mentally entertainment is sent out on the air waves. ranged to put lines into resort places where cooled and entertained, the broadcasters Fitting the program to the calendar has the sensitive microphone can carry the echo must so adjust their own Surroundings that become an art with those whose business of the rolling waves or the suggestion of their artists really feel cool and refreshed. it is to decide what is suitable entertain- coolness by breeze -swept lakes. And so, already, all the ornate heavy drap- ment and what is not appropriate for sea- Even the courageous directors of the eries which add to the attractiveness of the sonal reception. It would be absurd to morning "gym" classes are prepared to do metropolitan studios are in storage and expect set owners to react favorably in their best or their worst to counteract that the rooms have taken on their light sum- torrid heat to the same entertainment which lazy feeling which even the early sun can mer trimmings. In the larger stations, cool- amused them while they were cosy before create among enthusiastic adherents to the ing plants have been installed and, where a December fire. And the station foolish gymnastic cults. this advantage is not available, electric enough to try such a futile system would The radio habit has been acquired by fans play their deceptive lure on the curly find itself without listeners. millions and even the temporary lack of locks of blonde sopranos and the placid any broadcast reception would be little brows of even the most ardent performers. HOT-WEATHER PLANS short of a catastrophe in thousands of Do that, regardless of how unpleasant The National Broadcasting Company has homes. But the habit of not listening could conditions may be in most city buildings, lined up its programs primarily with the become just as strong as the faithful tuning- . and a cool calm will prevail in the salons idea of holding its listeners in all sorts of in daily. That is the reason why stations where ethereal music and humor originate. weather and before the first sign of spring must double their efforts to insure a large (Continued on page 70)

"The general idea right sow is to frigidize the music and freeze the ethereal atmosphere so realistically that a receiver next month will make a sun -filled porch seem like Greenland, and the living room reminiscent of piney, breezy mountain retreats."

www.americanradiohistory.com 18 Radio News for July, 1928

Why There Are Radio Fans them for an odd size tubing that can't I could only catch a word or two now anti be bought in the open market. I remem- then, but I heard "WRNY" on Saturday Editor, RADIO NEWS: ber, for example, the hooey they broadcast night and also your asking for reports. very coil in and were bad. On Monday May I comment on your editorial in the regarding the mysterious "N" Swinging static it? A heard "New York" a couple of April issue, announcing a change in policy the Lodge circuit. And what was night I could wind in times. for RADIO NEWS, particularly as it relates to simple solenoid that anyone you in the subscriber's letter that accompanies it. ten minutes, and for as many cents. On Monday night I tuned after Lon- I have been in the magazine field for In these days, of course, there is much listening to 5SW broadcasting 2L0, here twenty years and know something of your that we can't do; but there is also much that don's midday session. It is received problem. Also, we can. Any man who hasn't enough very clearly as a rule and at good strength. I have been a radio ex- station perimenter since the first peep of broad- mechanical instinct to wind a better coil Your station is the only American WGY casting, and at one time devoured every than most of the manufactured ones isn't I have heard so far, but I understand at loud- speaker magazine devoted to the subject. But, like safe to be trusted with a wheelbarrow. is received here, sometimes use a two-tube set, Mullard your correspondent, I have lately become Certainly we can't get excited over kits, strength. I M. 3 valves, .00015 tuning disgusted with most of them. Their con- worthy as they may be in their place. One P. and Pilot structional articles are mere write -ups for may as well say he makes his own clothes, condenser. the kit manufacturers, and the rest of the since he buys them in three pieces and puts L. S. CuFPE, space is padded with blab. them together. "Avalon," Constitution Road, But I think he is unjust in including Windsor, Brisbane, Queensland, Australia, RADlo NEWS in this categorical denunciation. In my opinion it is the one magazine in the THIS page belongs to the readers field to which such criticism sloes not apply. of RADIO Nr:ws. It is theirs for The reader lias a right to resent the the purpose of discussing fairly and Gets His Money's Worth hooking-up of articles and advertisements. frankly the needs of broadcasting from Editor, RADIO NEWS: But shouldn't he be shown how interrelated the standpoint of the great public who are his interests and those of the adver- listen in. The letters repte.ent, not I cannot sign myself a regular subscriber, tiser? A number of years ago I saw a necessarily the editorial opinion, but but I have not missed many issues since I testy old lady, who had just bought her that of the writers; who are, in the edi- became interested in radio. I am just at favorite woman's magazine, vindictively rip torial belief, fairly typical of groups of present a B.C.L. who prefers to roll his off the advertising pages, then settle her- opinion among the radio public. Make own; but I have other ambitions, and have self to enjoy the body of the magazine. your letters concise and offer construc- received much valuable help from your col- She failed to realize that but for those tive criticism when you can; remem- umns. advertising pages the literary matter would bering always that there is something American -made parts are the only kind have cost her several dollars, instead of to be said for the other fellow's side. available here, and none too plentiful; and ten cents. Address The Editor, RADIO NEws, there is also a 35% duty on them; so sub- But why are radio editors, as a class, so 230 Fifth Avenue, New York City. stitutes or makeshifts have often to be re- blind to the real reason for the reader's sorted to, and your "wrinkles" page often dying interest in their publications? To helps out. I have been reading the corre- me, it doesn't seem to be particularly Again let me say that I have never known spondence in your columns, concerning abstruse. RADIO NEWS to be guilty of any of these catering to the B.C.L. The amateur or- The force behind the radio craze of a stupid sins, and my hat is off to you for ganization has its own magazine to tell what few years back was not so much the won- this reason. But if you want to see your members are doing; so why expect others der of radio as it was the creative impulse circulation jump, open up a roomy depart- to do it too ! I think you are hitting the that exists in the most of us. Every man ment to the doings of the real experimenter. happy medium. is a pseudo -scientist at heart, and here was All of us are doing things that would make Being something of a DX hound, I fol- the one perfect toy he had been waiting interesting reading for the rest of us. 1 low reports with interest, though I have for since childhood. Here was something venture to predict you would get some sur- nothing unusual in my log. Regarding day- he could fiddle with eternally and some- prises. Also, I think you could lill the light DX, one of the St. Louis stations, thing potential of most amazing results. pages without cost. For my own part, if KMOX, comes in quite often, and some of Above all -and here is the vital point -he I had done anything that I thought would the Chicago stations. I believe the longest could "make it" himself. interest my fellow experimenters, I should DX record here is one of the California It isn't the mere radio listener who buys be mighty glad to pass it on to them. stations, but that is rather vague. My own the magazines and supports the parts In any event, give its something to do. longest daylight reception was KDKA, 1,050 stores; it is this eternal tinkerer who will WALTER DE MARIE, nines, on an 8 -tube set. start out with ten dollars to buy a pair 34 Pierce Street, New Rochelle, N. Y. I believe I would sooner have receiving of shoes, and sneak home with a trans- conditions as they are at present in this former instead. Yet the magazines, illogic- part of Canada than as they are in most ally enough, seem to be doing all they can parts of your country. True, the local sta- to stultify the interest of the very one who From Way Down Under tion is a government monopoly; and I hope makes their existence possible. Everything it continues to be so, despite the howls of Editor, RADIO NEWS: is done to induce him to buy something he certain business interests, the principal of doesn't need, and could make better him- I heard your short -wave station 2XAL which seems to be the grain trade, which self if he did. They stretch a construc- from 11.15 p. m. till about 11.50 p. m. last wants to put in a string of stations across tional article into three instalments that night (Feb. 6). When I tuned in you were Western Canada, to offset the effect of the could be condensed to a column. They in- giving a physical -culture session, and after wheat pools of the Prairie Provinces. troduce trick dinguses that are unneces- that I heard three or four musical items. I As for the dollar license fee, in Manitoba sary to the circuit; they make mysteries of had you also on Saturday night (Feb. 4) at only half of it goes to the support of the commonplace details. Even when coil con- the same time and physical culture as be- local station; the other half here and, in the stants are given, they are careful to give fore. The announcements weren't clear; (Continued on page 85)

www.americanradiohistory.com Radio News for July, 1928 19

A DX WRINKLE MORE BOLSHEVISM A FAITHFUL REPRODUCER RADIO DEALER: CURIOUS NEIGHBOR: NULL: "My set is "And here is just the "What's the idea. of an LW.W." burying your radio thing you want for V o I n: "Waddaya connection in those your radio set tó mean, I.W.W.?" make it complete; this old coffee grounds NULL: Won't "It is the latest in for, anyway ?" Work." loud speakers." BOILED OWL: "Oh, -II. N. Webster. I'm just trying to see Itemo PROSPECT (not s- a bachelor) : "No, if 1 can get Java this ,,,,,,,,,,,,,,,,,,,,,,1,,,,1,,,1,.,,.,,,.,.,.,,,,,,,,1,,,, 11.,,,,1.,11 ,11,,,1,,,,,,1,,,,,,,,,,:,,,111,,,,,1,1,,,,,,,.,,,,,, never mind showing it; way. " I've got an old model at home now that -Leslie Carpenter. page is devoted to humor of purely THISradio interest; and our readers are in- repeats everything she hears." AN UNSOLVED MYSTERY OF RADIO vited to contribute pointed and snappy Jokes -no long- winded compositions-of an SET OWNER (more in sorrow than in original nature. For each one of this na- HOME, SWEET HOME! anger) : "What I can't understand about ture accepted and printed, $1.00 will be JERRY: "And how did you enjoy your paid. Each must deal with radio in some stay in Havana!" this radio business, anyway, is how Static of its phases. Actual humorous occur- always knows what nights I ask company rences, preferably in broadcasting, will be CARRY: "Oh, it was wonderful! Why, we preferred. Address Broadcastatics, care got Kansas City every night on our radio! in to listen to the programs. "-Frankliw RADIO NEWS, 239 Fifth Avenue, New Nordling. York City. -Mollie Zacharias.

a,1,111110,1111,11,11..,1.111111114 ll,,,,,,,,,,,, ,,l,,,,,llll,,,,,,011,.,,.l,..,,.,,,,l,l ,11,,,1,,,,,,,, n PAPA BECAME A SUB -CHASER SHOULD HAVE MASKED HIS VOICE COULD IT HAPPEN TO YOU? SSIITI3: "What do f , "Hey, Willie," called Big Brother, Once there was a you know about this? 5áU(t`41. "pa wants to know Fan so tight The! e a er says that f.- r 0. , P P q. I he wouldn't send an a long- wanted crimi- ' > r where his loud speak- i -- er is ?" Applause Card. He nal owes his arrest to "I got it in the went hunting one day, the radio. Someone`-` bathtub," said Willie. and it began to rain; i recognized his voice *s- ' "I'm playin' sub- so he crawled into a ., in a broadcast." -*. hollow log. He felt F JoNEs: "Hiu. This ì- marine, and that's the periscope !" the thing swell, and isn't the first time the radio has squealed." was soon wedged in so tight he couldn't get PLAY THIS ON YOUR PHONOGRAPH out As he waited death by starvation, he CHEAPER TO MOVE - new SWEET YOUNG THING (in music shop): began to think of all the mean things he JACK: "I think I'll have to get a "I'd like to get a good DX record, please. had done. Then he thought about the radio set." My friends say that every good radio set Applause Card and it made him feel so Jim: "Why, what's the matter with the ought to have one. " -H. N. Webster. small he crawled right out. one you have ?" Moral: Don't let a two -cent stamp cause JACK: "I can't meet the payments on it." SHE MUST BE A DIVA you such misery.-Leslie Carpenter. -Mollie Zacharias.

SOPRANO: "I've been FINANCIAL CLARIFIER NEEDED PREVENTING A out all clay shopping, t 1 MABEL: "'l'he inter- SHORT CIRCUIT and 1 certainly got a ference is just awful NANNE: "Why do bargain." on our radio. Is they call that new BASSO:. "What did yours clear? catcher a `super- you buy now ?" LILLIAN: "Oh, no, het?'" SOPRANO: "I got an not yet. We've got PIIAxNE: "Because expensive new radio J three more payments he's a receiver that set for a song." l on ours." gets everything!"

RADIO RHYMES No. 9

NOT ONE DAS( PASSES By THE LATEST TUBE Oft THE LATEST CTAOGET FOR QUT C-rER1TLE t2EADEtZ, Bl1T THERE'S HOOK-UP RARE, - YOUR 5ET, VJ - 90ME cIEW o ce. tN OR. 13ATTERy BEYOND 02 ELSE THE NEWEST THE LÁT T T ttNtr RAOt0 WARES -- COMPARE, - CABtNHT. cN r2POCÓ

www.americanradiohistory.com News for July, 1928 20 Radio

Under this heading, RADIO NEWS publishes each month descriptions of the latest developments in the extremely interesting field of television. Practical Demonstrations Scheduled for WRNY By Theodore H. Nahken

WITHIN a short time after the channels, with comparatively simple trans- 10,000 -cycle band; which means that a car- appearance of this issue of RADIO mitting and receiving apparatus. Although rier -wave (920 kilocycles in the case of NEws, the first television broad- the writer does not claim he will be able WRNY) can be modulated by impulses up casting experiments to be con- to provide images of great sharpness, their to only 5,000 cycles in frequency. ducted by an American broadcast station, definition will at least be great enough to The receiving apparatus necessary for on its regular wave in the 200 -500 -meter make them readily distinguishable to the the reproduction of the televised images band, will be macle over WRNY, New York human eye. The degree of distinctness is will be of such comparatively simple con- City. This pioneer work will be clone limited by the fact that broadcast stations struction that any radio experimenter, under the direction of the writer with ap- must keep their radiated waves within a given the few essential components that he paratus of his own design and cannot make himself, will be able construction. 'l'he plan is to to assemble a complete instru- give an initial demonstration of ment in a few evenings. The the system in the Hotel ltoose- receiving televisor will form an velt, New York, where the stu- independent unit, and will be dio of WRNY is located. A equipped with a cord which television transmitter, or "tele- will connect to the regular out- visor," will be installed here; put posts of the broadcast re- and the image of a person will ceiver. be broadcast on the 326 -meter ANNOUNCEMENTS wave of WRNY from the In the present state of af- transmitter proper, which is fairs, it will not be possible to situated at Coytesville, N. J. receive both broadcast voice or A receiving set with a televisor music and the television im- attachment will be in operation ages at the sane time, because in a room in the hotel, where the electrical impulses carrying the received images will be ob- either will occupy the full legal served by the editors of ltAnao "channel" of the transmitting NEWS, a group of newspaper system. First the WRNY an- men and a number of scientists. nouncer will speak, and then The object of the whole the television broadcasting will undertaking is to demonstrate commence. There will be a slight the practicability of radio tele- pause between the end of the visieu, on the regular broadcast speech and the start of the

Top: The photoelectric-cell unit, removed from its metal container. The cell round object behind the reflector is a lens. Right: The back of the televisor, itself is the pear-shaped bulb in the foreground, the other tubes being A.F. showing the photoelectric cell's can behind the revolving disc. The driving amplifiers. Left: What you would look at if you were being "televised." The motor (not .chinon) fits on the baseboard.

www.americanradiohistory.com Radio News for July, 1928 21

MR. THEODORE NAKKEN, the author of the accompanying article, is a prominent radio engineer and inventor, and the holder of what is probably the most important patent in the television field. This patent, No. 1,522,070, reissue No. 16,870 (February 7, 1928), was granted for means of transforming light impulses into electric - current impulses, and covers all practical arrange- ments of elements and circuits for such transfor- mation. It will, in all probability, be the subject of a great deal of legal controversy and litigation. This article, the first of a number by Mr. Nak- ken, heralds a series of practical television demon- strations through the RADIO NEWS broadcast sta- tion, WRNY, New York, on its regular 326 -meter wavelength. The subsequent articles will describe the transmitting equipment in detail and will tell how the radio fan can make his own television re- ceiver to reproduce the broadcast images. This illustration nives a general idea of the televisor. Mr. Nakken is point- tilt(' to a little window through which the edge of the revolving "scanning" disc map be observed.

televisor, to enable the listener to discon- ing- current motors for general television accompanying illustrations show. 'l'he model nect his loud speaker and to hook on the work, because the motors running televisor receiver was still in "breadboard" form televisor or receptor. If the speaker is transmitters will not be fed by the same when this article was being written, so it left in the circuit it will emit a confused power systems that feed receivers in dis- could not be photographed. However, a babble of totally -meaningless noises. tant districts. detailed description of it will be published 'l'he actual television transmitting appa- in a forthcoming number of 1tAnlo NEWS, LIMITS OF EXPERIMENTS ratus has been practically completed, as the (Continued on page 84) It is hoped that, eventually, arrangements will be muck for simultaneous transmission of both speech and image, through the use of a separate broadcast station for each purpose. However, radio set owners will have to satisfy themselves with the marvels of television alone until the broadcast licensing situation ceases to be a political football and resumes its proper engineering aspect. The employment of separate trans- mitting stations will, naturally, necessitate the use of separate receiving sets; but the construction of a second tuner and ampli- fier to supplement the regular broadcast receiver is a simple matter. To start with, only faces will be trans- mitted. The received images appearing on the screen of the televisor will be about two -and -a-half or three inches square, and will appear at the rate of ten per second. This speed is enough to produce the illusion of motion. The minimum number required to produce this effect is eight pictures per second. Because of the inherent limitations and legal requirements of broadcast trans- mitters, there is little possibility of en- larging the images with pleasing results.

SYNCIiRONISM Both transmitting and receiving tclevisors will employ revolving discs. 'l'he all -im- portant problem of synchronizing them is solved by the use of a manual control at the receiving end. In other words, the operator of the receiving set will adjust the motor by means of a simple regulator (and visible indicator), and thus attain the adjustment that gives the best results. It Ilou' a person would be "televised." Mr. Nakken, the author, is standing behind his apparats. is not feasible to use synchronous alternat- rit the right is Mr. I. Goldberg. president of the Pilot Electric .Ifg. Co., makers of the televisor.

www.americanradiohistory.com Radio News for July, 1928 Vacuum Cameras to Speed Up Television

A Ray of Fast -Flying Electrons, Without Weight or Lag, Will 4/1 Replace Slow- Moving Shafts and Levers of Older Apparatus

By R. P. Clarkson

THE three great problems of tele- FAST WORK screen would he perfectly blank. In re- vision of moving objects are first, to cording a "fast- motion" picture, such as re- Suppose, for example, we wish to send analyze into a sufficient number of quires a 1 /100 -second exposure instead of electrical impulses, the instantaneous an image 10 inches square, which contains, of course, 100 inches. 1 /10, the condition would be the same - which is to be transmitted, so that square To have the image detail of the resulting only more so! the received image is well defined; second, image of an ordi- nary printed magazine quality, How can this apparent stumbling-block so to transmit the enormous number of there must be provision be overcome? My suggestion, in the appa- resulting impulses per second that the wave made for, say, 14,000 variations per square ratus described in this article, is to use for keeps within the legal separation of broad- inch in light and shade to be changed into not neon cast stations, now set at 5,000 impulses per electrical impulses. That the light -flash, a lamp or anything means 1,400,000 impulses second; and third, so to project the re- per picture, or at of the sort, but the impact of a stream of ceived impulses that, not only will the en- tire image be reproduced within one -tenth of a second but, also, each dot of the re- ceived image will be of such intensity or of such duration that the eye will retain ,`v SCREEN CONDUCTIVE while the rest of the image is sent. LENS ELECTRON COUPLING it .. CUBE PATH a Just as a motion picture is a quick suc- RESISTANCE LIGHT, cession of "still" pictures, so in television LEAK / BEAM IONIZED each image is built up of a quick succes- PATH sion of light impulses made visible. Be- VAPOR THROUGH CAMERA cause of the defects of vision, a succession CHAMBER VAPOR TUBE of pictures simulates motion, if they fol- FIG. IA AMPLIFIER low each other even at the rate of ten per TUBE second but, because of other defects, the eye must see each picture for a definite length of time, depending upon the inten- ,Sivap /iJ/eel schematic drawing, showin11 arrangement of the varions components sity of its illumination. So, when receiving of the television apparatus proposed by the author. a television image, the eye will retain all the flashes of light during a tenth of a least 14,000,000 impulses per second for a electrons on a screen of material which second because of the "persistence of vis- moving picture; each impulse resulting in is not only "fluorescent," but also "phos- ion;" but each flash must make a definite a light flash for one fourteen -millionth part phorescent." In ' other words, to use a register on the eye. This requirement lim- of a second. The eye wouldn't see this screen which not only glows when struck its the speed of. the flash and puts a physi- flash at all and, although the pictures were by electrons (as in an oscillograph) but one ological limitation into our problem. faithfully sent and recorded; to the eye the which will continue to glow after the stimu-

CLARKSON TELEVISION CAMERA H T0 OSCILLATOe ; F). F CAMERA At ?.ELEMENT TUBE

OUTPUT TO RADIO TRANS MITTER H., HEATER COIL R COUPLING RESISTANCE G TRANSPARENT WALL S = WIRE GAUZE C= COMPOSITE PLATE OF LEAK Cl NON - PHOTOELECTRIC CONDUCTIVE CUBES J = VAPOR CHAMBER

What the television "camera" of the future may look like. P projecting tube. A and B are the coils whose magnetic fields and F are plate and filament, respectively, of the electron- influence the electrons which stream through the opening in P.

www.americanradiohistory.com Radio Ncws for July, 1928 23

least, there is the impossibility of syn- chronizing the transmitting and receiving disks at that speed. The only answer I know to this problem is the use of a weightless beam of electrons moving under the influence of a changing magnetic field. This is the type of image - scanning device I have suggested in the television camera and projector. To secure a changing magnetic field of any frequency is a simple problem, readily solved by means of a generator or an audio -frequency oscillator.

WAVELENGTH PROBLEMS Lastly, how can frequencies in the mil- lions be sent, within the legal restriction of 10 kilocycles separation between broadcast stations? This is a problem in which the apparatus for television has no part. The solution is as valuable for increasing the available spectrum for broadcasting as it is for pictures. Just how to solve the prob- lem on the high wavelengths, nobody knows; but the direction in which the solution lies is very clear. In the first place, why is there such a thing as a "waveband?" Why can't voice or music be sent over the single frequency of the carrier -wave, by modulating the am- plitude of the wave without affecting the frequency? By our present systems of The radio receiver of the future undoubtedly will have attached to it a televisor, so 1 ransmission, we simply that the listeners will be able also to "see" broadcast events. add our modulation frequency to the carrier, or subtract it his has ceased. Not only will this make with its spiral openings (patented by the from the carrier, or do both. Nobody visible a short impulse but, also, it makes inventor in 1834) whether of the original knows why this should be necessary; I, for possible the use of less intensity of the glow form as used by Alexanderson, with lenses one, believe it isn't necessary. If we have in order for the eye to be stimulated. It in the openings as used by Baird, with slits n carrier -wave of 500,000 cycles and send will also lend itself to the blurring of the as suggested by Rothschild, or in the form out also a voice -wave of 1,000 cycles, we successive dots of light into each other to of whirling optical plates as Jenkins makes may make a 501,000-cycle wave, in effect, imitate more nearly a photograph. it, is perfectly useless for this purpose; and a 499,000-cycle wave. These are the not only because of the limitation on the two "sidebands." But why not simply de- SCANNING APPARATUS speed of mechanically-moving parts, not press the tops of every 499 waves, leaving Now, as to dividing the image up into only because of the limitations of size to the 500th, so that in our receiver we get 1,400,000 dots or impulses in one -tenth of make room for enough holes, but also be- the .500,000 -cycle wave modulated in ampli- a second, no device yet suggested can begin cause of light limitations, as sufficient light tude to give 1,000 crests or impulses? to approach that task. The Nipkow disk won't pass through the holes. Last, but not (Continued on page 76)

CLARKSON TELEVISION PROJECTOR

A-TO OSCILLATOR A PHOSPHORESCENT SCREEN

VACUUM TUBE

INPUT, FROM RADIO RECEIVER

I

The receiving televisor, similar in construction to the trans- ing tube. The image will appear on a phosphorescent screen. mutter, makes use of an identical two-element electron -project -. There are no moving parts at either end, except the electrons.

www.americanradiohistory.com 24 Radio News for July, 1928

+ i, +

1 A, D i R 1 AL

What You Should Know Í

i' the in Common Usè, Variousps I b red Ccn ield

I

with The aerial of station 1P11AF, Round Hills, Mass., owned by Col. transmitting aerials have more, longer and heavier wires, E. H. Green. Though electrically similar to receiving aerials, higher and snore substantial masts, and must be highly insulated.

EVERY broadcast listener who is lively poor aerial is used; but it is seldom ginner should not become discouraged if blessed (or cursed, as the case may that a poor set can be made to deliver ex- it is impossible for him to follow the usual be) with the slightest knowledge of ceptional results by using a good aerial. directions exactly; for the rules governing radio is continually being pestered From the above statement, the reader the erection of aerials are quite flexible by his friends and neighbors with questions should not gain the impression that aerial and it is possible to make many changes in on aerials. There seems to be a countless design need not be considered, because this an aerial without materially affecting the number of queries which may be asked on is not true. However, he should always results. this subject, and the beginner in the field bear in mind that the importance of much In this article the writer will attempt to usually considers each phase of. the prob- of the popularly -given instructions on the give general directions for the erection of lem most vitally important. subject has been greatly exaggerated. Of receiving aerials. The conditions which are view- It is said that "a little knowledge is a course, there are a few physical laws which considered ideal from the theoretical dangerous thing," and the newcomer in govern the design of aerials, and these must point are described here; but the reader radio who asks a recruit for his opinion ün be taken into consideration. But the be- must remember that it is not to be expected the design of an aerial usually discovers the that he will be able to follow out all of truth of this for himself; because, more the suggestions, particularly if he resides often than not, if he follows the advice in a city apartment. Therefore he should he receives he will waste valuable time in endeavor to construct an aerial which pos- needless experimenting. This is because sesses as many desirable features as pos- C)Q sible, and satisfy himself with this. In most broadcast listeners, before acquiring practical experience, are of the opinion that most instances such an aerial will give satis- the results obtained from a receiver are INVERTED-: faction. TYPE TYPE dependent almost entirely upon the char- WHAT IS AN "ANTENNA ?" acteristics of the aerial. Therefore, while gaining experience, many fans change their The antenna system of the usual radio aerial a dozen times or more in the effort receiver (or transmitter) is made up of to obtain best possible results. Also, if four parts; riz, the aerial proper, the aerial the receiver fails to work, they are apt to lead -in, the ground wire and the ground. LOOP In the transmitting station, it is the func- consider the aerial the cause until it is VERTICAL (COIL) proved not guilty. TYPE TYPE tion of the aerial to act as the radiator of the energy produced by the power tubes of NOT THE ONLY FACTOR the sending apparatus. This energy is in On the other hand, the novice who asks the form of a high -frequency oscillating advice from a person who is really familiar current, in the aerial, and by its presence with radio practice receives a few simple produces electromagnetic waves in the ether. rules to follow when erecting an aerial and In the case of the receiver, the aerial acts is told not to worry about its efficiency Fig. 1. The shaded areas indicate the relative as a co /lector of such electromagnetic waves. sensitivity, to signals arriving from different after it has been erected. It is explained directions, of the four principal types of aerials. Often, in two -way communication, the same to him that a good set is capable of satis- The vertical -wire aerial is not directional, the aerial is used both for receiving and for loop most so; but the "T" and "inverted-L" factory performance, even when a compara- types arc most convenient for general use. radiating radio signals.

www.americanradiohistory.com Radio News for July, 1928 25

Antenna systems used for sending and 'sitivity to receive distant stations and ample receiving radio signals are of two general selectivity for separating the local broad- ENAMEL types; first, those which act primarily as casters. On the other hand, if the aerial COVERING electrical condensers and, . second, those were made larger, the set would probably which act primarily as electrical inductors. tune broaclly and local interference would The first type is the more generally used, be experienced; but, if the aerial were and is the basis of the discussion in this shorter, difficulty would be encountered in article; it consists of an aerial-and- ground receiving distant stations. connection. The second type is the loop 'l'here are places, however, where aerials antenna, and this is used only in connection either longer or shorter than 100 feet are with super -sensitive receivers and for di- required. In rural districts, where the rection- finding purposes. (See Fig. 2.) ' nearest broadcast station is more than 25 miles away, interference problems are al- THE "CONDENSER" AERIAL most unknown, and, under these conditions, A simple antenna of the condenser type a long aerial, having a length as great as would consist of two metal plates separated 150 feet, may be used. On the contrary, by air and insulated from each other except in congested city districts, where there are by a wire, known as a lead -in, which con- several powerful broadcast stations very nects the receiving or sending apparatus nearby, it may be found necessary to use between the two plates. In an antenna sys- a very short aerial. Usually one 75 feet tem of this type, the efficiency would be long will be found to possess ample selec- determined by the separation between the tivity but, in some cases, it will be neces- two plates and by the capacity formed by sary to reduce the length of the aerial to the two plates. However, from a practical 40 or 50 feet in order to eliminate entirely viewpoint, an antenna of this type would local interference from the receiver. 7- STRANO SINGLE not be very satisfactory. In order to make In computing the length of an aerial, it WIRE WIRE it perform with a high degree of efficiency, is important to remember that the lead-in the size of the two plates would have to wire has just as much effect upon the opera- be made so large that the device would be tion of the receiver as the aerial wire itself. Therefore, if is very expensive and also cumbersome. it desired to erect a 100 - Fig. 6. Radio -frequency current flows on the In actual practice such metal plates are foot aerial and the lead -in wire is 20 feet surface of conductors and R.F. resistance may long, the aerial be decreased by increasing the surface area. not used as parts of an antenna system. wire should not be more With the same amount of metal, stranded wire Usually one or more wires are suspended than 80 feet long. This is where a great has a greater surface than solid wire; enamel ninny listeners make insulation also increases the surface by sepa- from insulators in the air and these serve a mistake. Because rating the strands. in place of one of the plates. The other their aerial wire is only 75 feet long they plate is replaced by the ground itself. The expect great selectivity; and they are very much wires suspended in the air are known as surprised to be told that the inter- four wires must be employed, for mechan- the aerial, and the air acts as a dielectric ference they experience is caused by their ical reasons. Usually, when three or four between the aerial and the ground. Thus wires are used, the aerial has an effective it may be seen, the usual antenna system is length approximately 50 per cent greater really a large condenser. than its actual length in feet. Aerials of different sizes and shapes have been designed to meet different requirements PULLEY' and, by changing the mechanical character- LOCATION AND INTERFERENCE of an aerial, is WOODEN SPREADER k The rule when istics it possible to make IN$UL/LTORE second to observe, putting it either "directional" or "non- directional," INSULATOR up an aerial, is not to run the wires near and efficient or inefficient. Of course, dif- buildings, wires, trees or large metal ob- AERIAL ROPE ferent rules apply to the design of trans- WIRES jects. When the aerial wire runs through mitting and receiving aerials; the branches of a tree, over the but the for- " \labh, TOR metal roof mer will not be considered in this article. of a building, or parallel to telephone or Ir STAYS lighting wires, much of the energy is ab- LENGTH OF AERIALS sorbed before it reaches the receiving set. LEAD'IN WIRE In the first part of this article it was This has the effect of increasing the re- stated that a few simple rules may be used sistance of the aerial and, as a result, it reduces the sensitivity and to govern the erection of all types of re- Fig, 5. Flat -top construction is probably most the selectivity ceiving aerials; these are stated in the fol- popular in multi-wire receiving aerials. A of the receiver. wooden rod is used as a spreader and the lead- Wherever possible, when lighting wires lowing paragraphs. in Ware takes the shape of a fan; this diagram, First, the aerial need not always be long. shows the usual method of construction. are a problem, the aerial should be so placed Many radio fans are under the erroneous I that it crosses these wires at right angles. impression that an aerial of great length In the case of a metal roof, the aerial should long aerial, 75 feet of which is insures excellent reception, but this is not lead -in wire. be supported as far above the building as i - frequently happens always the case. In most instances, an It that a set owner possible; and, where branches of trees cause aerial with an over-all length of approxi- wishes to use a long aerial, but is unable trouble, they should be so trimmed that to do so because of lack mately 100 feet will provide most satisfac- of space. Under they do not come in close proximity to the these conditions a multi -wire tory performance. With an aerial of this aerial of the aerial wires. Often, when a tree is used !cage or the flat -top type may be used length, the average set has sufficient sen- to as a support for an aerial, it is best to advantage. In the usual receiving installa- terminate the aerial several feet before it tion, a long single reaches the tree, by inserting an insulator wire is more satisfac- between it and the supporting wire leading PULLEY-- tory than a multi -wire to the INSULATOR--+ trunk. aerial; but, where it After the aerial has been erected, it should is impossible to con- ROPE., be remembered that the lead -in wire re- struct a suitable quires the same care that was given the single -wire aerial, the aerial. Because the lead -in roust enter the use of several wires house, is difficult METAL RING it more to keep it away ,iiiiii often improves re- from surrounding objects; but, nevertheless, sults. If an aerial of this is equally as important as in the case LEAD-IN WIRE the flat -top type is to of the aerial. Where the wire must follow be constructed, two the side of a house for a distance, it is i or three wires may usually wise to support it on insulators, Fig. 4. 7lIe cage aerial is a popular design for a multi -wire aerial. Metal be used; but, if a which should be spaced by brackets at least rings are used to separate the wires and each wire must be securely soldered cage -type aerial is de- a foot and a half from the walls of the to each ring. The rings are spaced 15 or 20 feet apart over the entire length of the aerial. cided upon, at least building. Also, the wire should enter the

www.americanradiohistory.com CZ's for July, 1928 26 Radio bouse at a point as near the radio receiver energy which is picked up is very feeble, as possible. and it is essential that none of the current be wasted, if distance reception is desired. DIRECTION OF RECEPTION As it is the purpose of the insulators to from leaking to the The directional characteristics of the prevent the current GALVANIZED it passes through the re- IRON WIRE. various types of antennas is the next point ground before AERIAL, good insulation WIRE which will receive consideration. In this ceiver, the importance of PULLEY connection it should be pointed out that may be appreciated readily. i the average radio listener directs too much In a radio aerial, insulators arc used at effort toward calculating the probable di- each end; they serve to connect the wire INSULATOR which signals will be re- of the aerial to the rope or wire which sup- rection from most LINE/ ceived. The fact is that, at sea or on a ports it in position. Also, insulators are CLOTHES and wide prairie, the directional characteristics connected between the lead -in wire of certain types of aerials may be quite any support which holds that wire in posi- noticeable; but, in most locations, the sig- tion. In addition, an insulating tube is WEIGHT nals of all stations are reflected to such required at the point where a lead -in wire an extent, by buildings or other sources of enters a building, and the lead -in wire is wave interference, that the characteristics passed through this insulator. In other of the aerial have very little to do with the words, insulators are used at all points actual direction in which the receiver pro- outside the house where it is necessary to vides best results. provide supports for the aerial or lead -in For the benefit of those who are inter- wires; and it is the purpose of these in- aerial system from Fig. 3. This drawing shows a suitable method ested in this subject of directional charac- sulators to prevent the for attaching an aerial to a tree. The weight contact with any- at ait times. and teristics of aerials, Fig. 1 shows graphic coming in close electrical takes up the slack in the wire which might provide a path to the prevents the wire from breaking when the tree thing sway in a heavy wind. ground for electricity. WIRE TO SET. On the inside of a building, it is equally important to prevent leakage of current when selecting an insulator for outdoor use, from the aerial lead -in; but it is easier to is whether it absorbs moisture. For ex- insure against such an occurrence, for the ample, a high -quality glass is excellent in woodwork and furnishings are dry and are this respect because it absorbs practically fairly satisfactory as insulators. Therefore no moisture, it is a very good insulator, (usually at the point where the lead -in en- and its shape can be designed to provide ters the house) an insulated wire is soldered ample mechanical. strength for the purpose. to the bare wire used in the aerial and ex- Porcelain which has been properly glazed is ternal portion of the lead -in. The insula- another excellent material for insulation tion on this wire is all that is considered purposes, and the highest -quality insulators Fig. 11. A good ground connection is as im- necessary to prevent leakage. of this type possess the same desirable portant as a good aerial. A lots- resistance Outdoor insulators are made in various qualities as glass. However, frequently connection to a cold -water pipe provides an excellent ground; and the best way to make sizes, and from various materials, in order porcelain insulators are glazed only on three this connection is with a standard ground clamp. to satisfy all requirements. The length sides; such insulators absorb considerable for ally the way in which the various types varies from three inches for small receiving moisture and are therefore unsuited insu- differ. will be noticed that the vertical aerials to two feet or more for powerful outdoor use. Usually hard-rubber It two aerial provides uniform reception in all transmitting stations. The materials used lators are not as satisfactory as the directions and, for this reason, it is the are selected because of their ability to act types first referred to. When exposed to ideal type for all purposes. However, for as an insulator under all climatic conditions; the weather hard rubber deteriorates and in the mechanical reasons, this type of aerial con- glass, porcelain, hard rubber and special - in time loses its strength; also, time, struction is seldom used. The "'I "'-type composition materials are a few of them surface becomes rough and as a result holds composition aerial is the next best, but this is not very frequently employed. moisture. There are several popular because it must be twice as long The most important thing to consider, insulators which are very satisfactory but as the inverted -"L" -type aerial, in order to provide the same results. The inverted "L" -type aerial is theoretically the most unsatisfactory of the three, but it is a much -PULLEY more practical design and it actually de- MAST(2'X4") AERIAL WIRE livers results entirely satisfactory. under PULLEY -__ ROPE most conditions. \ INSULATORS The secret of making an aerial non -di- ROPE -MAST(2'"x4 ") rectional is to support it as high in the air GUY WOODEN SUPPORT- as possible. It has been found that, with GUY WIRES aerials less than 20 feet high, the directional characteristics are sometimes quite pro- nounced; but, as the height is increased, these effects become less noticeable. Aerials from 30 to 60 feet in height are entirely satisfactory for average reception purposes. Of course, wherever it is possible to do so, one should plan an aerial so that it will run in the direction found most satisfactory for reception in the direction desired. How- ever, where so many fans make their mis- take is in an effort to provide the aerial with desirable directional characteristics which causes them to sacrifice other desir- able features such as proper length and lo- cation, which are usually far more important. 1 i - .. t ; BRACKET & INSULATOR INSULATION GROUND WIRE % LIGHTNING ARRESTOR Insulators are an important consideration when erecting a radio aerial. and there are receiving aerial. many different types of insulators available Fig. 7. This drawing gives complete details for constructing an average radio Masts are used to raise the aerial wire as far from the roof as possible, and brackets keep the for the purpose. In a receiving aerial, the lead -in away from the house.

www.americanradiohistory.com Radio News for July, 1928 27

none have the lasting qualities of glass or much as 25 per cent. Therefore, the enam- a high-quality porcelain; i.e., in time they PULLEY AERIAL, eled covering is highly desirable, and this are affected by the weather in one way or IRON WIRE INSULATOR is particularly true in large cities because of acid fumes liberated by factories and another. MAST coal -burning furnaces. CHOICE OF \VIRE Aluminum wire is not very satisfactory The type of wire which will be most for radio aerials. The tensile strength of satisfactory is another important problem aluminum is not very great and it cannot for the set owner to decide. There are as be soldered with ordinary solder; also, it many different kinds of wire which may be GUY WIRES corrodes very rapidly. Phosphor- bronze used as there are insulators, and each has wire possesses characteristics which are its particular advantages. For example, LEAD-IN INSULATOR similar to those of copper, but has greater wire for use in aerials is made of bare cop- strength. As bronze is more expensive than - per, aluminum, phosphor -bronze, copper GROUND WIRE copper, there is no advantage in using it, clad iron, gold -plated copper and enameled except in cases where a very long aerial copper. Also, it is available in several sizes, is to he erected. Also, bronze wire is not 22 Fig. 9. This drawing shows an excellent ar- cor- including rope with seven strands of No. rangement for a receiving aerial. When this sold with enamel insulation and, as it and even larger wire, and single strand up method is followed, both the aerial and lead-in rodes, it may not be as satisfactory as No. 14 16 wire. wires are kept free from obstructions. The -clad iron wire, to and aerial wire may be fastened to either a tree enameled copper. Copper In selecting wire, the important points or another building. when new, is equally as efficient as copper to consider are; first, its mechanical from the electrical viewpoint and, in addi- strength; second, its resistance to radio - enamel, the effective surface is still further tion, it is much stronger mechanically. frequency currents; third, its lasting quali- increased. However, it is not generally available with ties; and, fourth, the case of making sol- enamel insulation, and it must in time be dered connections to it. EFFECT OF CORROSION replaced because the copper coating wears The mechanical strength of aerial wire The quality of the metal on the surface off, leaving ordinary iron wire, the resist- must be considered when the wire is to be of the wire, also, has an effect upon the ance of which is very much higher. stretched over a long span. Where it is R. F. resistance. For example, the R.F. Either gold- or silver -plated copper wire planned to make the aerial 150 feet or more resistance of a length of clean copper wire is satisfactory for use in aerials, but it is in length, aluminum and copper will not might be originally 10 ohms; but, after it has unnecessarily expensive. Both gold and been exposed to the weather for a few months, the corrosion on the surface might increase the resistance of the wire to 15 ohms for R.F. currents. In the wires made and sold especially for aerials, many methods have been used to decrease the surface resistance of the wire. Probably the most popular is the use of an enamel covering, which protects the metal from the weather and, in this way, prevents corrosion. Other manufacturers LIGHTNING ARRESTOR gold-plate the wire, as gold is a good con- ductor and is not subject to corrosion. In the case of the copper -clad iron wire, the makers take advantage of the fact that Fig. 10. A lightning arrestor is required by flow on the surface of the the insurance regulations, in every case where R.F. currents an outside aerial is used. This device is con- Fig. 2. Every tuned radio circuit must include wire, and use a less expensive but stronger nected across the aerial and ground wires, at both inductance and capacity; we see here how metal in the core of the wire. the point where they enter the house, to conduct this rule applies to the antenna circuit of re- atmospheric electricity direct to ground. ceivers. Figs. A and C show an aerial-and- Single- strand, enameled copper wire of ground system in schematic and picture form; No. 14 or No. 12 gauge is probably the 13 the of the loop antenna. Figs. and D, circuit most popular and roost satisfactory wire silver are good conductors of electricity; for receiving purposes. This wire has suf- however, the thin gold or silver plating is be satisfactory for the purpose and either ficient mechanical strength and offers a apt to wear off in a very short period of phosphor-bronze or copper -clad iron should very low resistance to R.F. currents, its time, leaving bare copper wire. be used. However, for the usual receiving enamel covering prevents corrosion, and it CONNECTIONS aerial which is less than 150 feet in length, is easily soldered. There is very little dif- copper and aluminum both have sufficient ference in efficiency between the solid wire When putting up an aerial, joints in the strength. and the stranded. The difference in re- wire should always be carefully made. In The R.F. (radio- frequency) resistance of sistance between solid copper wire and all cases where it is possible to do so, the wire is important, regardless of the type enameled copper wire is negligible when joints should he avoided; as they are a of aerial which is being constructed; as it the wire is new; but the increase in R.F. constant cause of trouble. For example, has a great effect upon the electrical effi- resistance caused by corrosion after four the aerial and lead-in may often be one ciency of the antenna system. In this con- months of exposure to the elements often length of wire; thus eliminating a joint at nection, it should be explained that R.F. causes a decrease in signal strength of as a place where it is difficult to make a resistance is entirely different from D.C. repair and still more difficult to discover (direct- current) resistance, and two wires a defect. having exactly the same D.C. resistance may When making joints in aerial wires, both have entirely different R.F. resistances. The the mechanical and electrical efficiency of reason for this is that R.F. currents (such the connection must be considered. In the as those caused by radio waves) flow on the aerial wire, if a connection is not mechan- surface of wire, whereas direct currents ically strorig, a strong wind is apt to blow penetrate through the entire wire. (See down the aerial. Likewise, if a good elec- C. Fig. G.) trical connection is not made, the air will In R.F. circuits the resistance may he be apt to corrode the wire and increase the decreased by increasing the surface area resistance of the aerial. Good electrical of the wire. This explains why seven- connections in the aerial are far more im- ,~ stranded No. 22 enameled copper wire is portant than in any other part of the radio used frequently in place of a single strand installation, because the action of the ele- of No. 14 wire which has approximately ments will quickly render a poor contact the same D. C. resistance. By using valueless. Therefore, it is highly impor- Fig. 8. In order to obtain best results, the be stranded wire, a greater surface area may lead -in wire should be kept free from buildings. tant that all joints soldered. he obtained with the same quantity of Where necessary, brackets should be erected to Although the ground. wire is not a part of support the wire at least 18 inches from the metal; and, by insulating each strand with building. (Continued on page 82)

www.americanradiohistory.com 28 Radio News for July, 1928. List of Broadcast Stations in the United States

Radio °só ú« Radio eó e« Radio ot Radio Call BROADCAST STA. oó 3oq Call BROADCAST STA. éq Call BROADCAST STA. Áv X% Call BROADCAST STA. Letter Location 3g y 3 Letter Location 3 a Letter Location 3f a3 Letter Location

KD KA East Pittsburgh, Pa.. 316 50000 KGEW Fort Morgan, Colo 219 100 KWBS Portland, Oregon 200 50 WDBJ Roanoke, Va...... 231 250 (Also 62.5. 42.95, and 27 meters and other KGEZ Kalispell, Montana 294 100 KWCR Cedar Rapids, Iowa 240 250 WDBO Orlando. Fia 288 500 short-wave transmissions on varying KG Fe Iowa City, Iowa 2.24 K W EA Shreveport, La. 213 100 (4XE, variable, 250 watts) power.) KGFF Alva, Oklahoma 205 25 KWG Stockton, Calif 345 50 W D E L Wilmington, Del 297 100 K D L R Devils Lake, N. D 231 15 KGFG Oklahoma City, Okla 216 K OW Portland, Ore 250 60 W DG Y Minneapolis, bl inn 286 500 K D Y L Salt Lake City. Utah 234 500 KGFH La Crescents, Calif 263 250 (Also 53. 54 meters, 100 watts) WDOD Chattanooga, Tenn 244 500 KEJK Los Angeles, Cal 252 250 KGFI San Angelo, Texas 220 15 K W K St. Louis, al 234 1000 WDRC New Haven. Conn 283 500 (6XAN, 105.9 meters. 250 watts) KGFJ Los Angeles, Calif 213 100 K W KC Kansas City, Mo 222 100 WO W F- W L51 Cranston, R. I 248 250 KELW Burbank, Calif 229 500 KGFK Hallock, Minn 224 50 KW K H Kennonwood, La 393 3500 WDZ Tuscola, Ill. (daytime) 278 100 KE X Portland. Ore 278 2500 KGFL Raton, N. M 222 50 K W LC Decorah, Iowa 248 50 WEAF tBeilmore, N. Y.....49250,000 KFAB Lincoln. Neb 319 6000 KG FN Aneta, No Dak 200 15 KWSC Pullman, Wash 396 500 W EA M North Plainfield. N. J. 263 250 KFAD Phoenix, Ariz 322 500 K G Los Angeles, Cal.(port ) 204 100 KWTC Santa Ana, Calif 273 100 WEAN Providence, R. I. 275 500 KFAU Boise. Idaho 286 2000 KG F W Ravenna. Neb 297 10 KWUC LeMars, Iowa (day). 244 1500 WEAO Columbus, Ohio 283 760 KFBB Havre, Mont 275 50 KGFX Pierre, S. D. (day) 254 K W W G Brownsville, Texas 278 500 (Also 54.02 meters. 250 watts KFBK Sacramento, Calif 275 100 KGGF Picher, Okla 207 100 KXA Seattle, Wash 535 500 WEAR Cleveland, Ohio 400 1000 KFBL Everett. Wash 224 50 KG G H Cedar Grove. La 213 KXL Portland, Ore 220 250 WEBC Superior, Wis 242 '250 KFBU Laramie, Wyo. 484 500 KG G M Inglewood, Calif.(port ) 204 100 KXRO Aberdeen, Wash 224 50 WERE Cambridge, 0610 248 10 KFCB Phoenix, Ariz 244 123 (6XAI, 66.04 meters; 50 watts) K Y A San Francisco, Calif 361 1000 WEBH Chicago, Ill 366 500 KFCR Santa Barbara, Calif 211 100 KGHA Pueblo, Colo 210 500 K Y W Chicago, Ill 534 2500 WEBJ New York. N. Y...,.250 500 KFDM Beaumont. Texas 484 500 K G H B Honolulu. Hawaii 227 250 KZM Oakland, Calif 231 100 W E B Q Harrisburg, Ill 224 15 KG HC Slayton, E KFDX Shreveport, La 236 250 Minn. 210 15 NAA Arlington, Virginia.. "434 1000 W B R Buffalo, N. Y . 242 200 KFDY Brookings, S. D. 545 500 KG HF Pueblo, Colo 210 250 W AA D Cincinnati, O 231 25 WEBW Beloit. Vila.,...... 258 500 KFDZ Minneapolis, Minn 216 10 KGHG McGehee. Ark 000 50 WAAF Chicago. Ill 389 500 WEDC Chicago. I6 242 500 KGH I KFEC Portland, Ore 214 60 Little Rock, Ark 000 15 WAAM Newark, N. J . 268 260 WEDH Erle, Pa 219 30 KFEL Denver, Colo 227 250 KGHL Billings. Mont 22 250 (Also 65.18 meters, 50 watts) WEEI Boston, Mass 208508 500 KFEQ 8t. Joseph. MO 231 1000 K G H O Fort Stockton, Texas 000 5U WAAT Jersey City, N..1' 240, 300 WEHS Evanston. Ill 100 K F E Y Kellogg. Idaho 23.2 10 KG H X Richmond, Texas 000 50 WAAW Omaha, Neb. (daytime)441 500 WE MC Berrien Spgs., Mich 484 1000 KFGQ Boone, Iowa 210 10 KGHP Hardin, Mont 263 50 WABC Richmond HIS, N. Y 309 2500 WENR see WBCN KFH Wichita, Kan. 246 500 KGJF Little hock, Ark 000 250 (Also 64.0 meters, 500 watts) WEPS Gloucester, Matta 297 106 K F H A Gunnison, Colo. 250 50 KG KO Wichita Falls, Texas 000 250 WABF Kingston, Pa 205 250 wWEEVwD Woodhaven, N. Y 246 500 KEHL Oskaloosa, Iowa 213 10 KG() Oakland, Calif "384 5000 WABI Bangor, Me. (Sundays) 389 100 St. Louis, Mo. (day) 353 1000 KFI Los Angeles, Calif 468 5000 (Short -wave transmitter. 10 to 40 WABO See WHEC WFAA Dallas, Texas 545 500 KFIF Portland. Ore 229 50 meters, 10.000 watts) WA B W Wooster, 248 WFAM St. Cloud, Minn RC Ohio 50 2.52 10 KFIO Spokane, Waal' 246 100 KG San Antonio, Texas... 220 250 W A B Y Philadelphia, Pa 248 50 W FAN Philadelphia, Pa 224 500 KFIU Juneau. Alaska 225 10 KG RS Amarillo. Texas 244 250 WABZ New Orleans, La 238 50 WFBC Knoxville, Tenn 234 50 KFIZ Fond du Luc. Wis.... "208 100 KG TT San Francisco, Catit 220 50 WA DC Akron, Ohio 238 1000 WFBE Cincinnati, Ohio, 246 250 KFJB Marshalltown, Iowa 248 100 KGU Honolulu, Hawaii 270 WAFD Detroit, Mich 231 100 WFBG Altoona, Pa 268 100 K FJ F Oklahoma City, Okla 273 5000 KG W Portland, Oregon 492 100000 WAGM Royal Oak. Mich 225 50 WFBJ Collegeville, Minn 273 KG Y Lacey, Wash 100 KFJ 1 Astoria, Ore 250 50 246 WAIT Taunton. Mass 214 10 W FB L Syracuse, N. Y 268 750 KFJM Grand Forks, N. D 333 100 KHJ Loe Angeles, Calli 400 1000 WA I iColumbus, Ohio 283 5000 W FB M Indianapolis, Ind 276 1000 KF)R Portland. Ore 240 500 (Also 104.1 meters; 50 watts) WAIZ Appleton, Wis 227 100 WFBR Baltimore, Md 244 +2.50 KFJ Y Fort Dodge, Iowa 232 100 WFBZ Galesburg, III 248 50 KF1Z Fort Worth. Texas '250 0 WFC I Pawtucket, R. I 242 100 KFKA Greeley, Colo 250 500 WFDF Flint, Mich 273 100 KFKB Milford, Kansas 242 -1500 WFI Philadelphia, Pa 405 500 254 THE list of stations here corresponds KFKU Lawrence, Kansas 500 to the latest list of W F I W Hopklnsville, Ken. , 261 1000 K F K X Chicago. Ill 526 2500 licenses issued by the Radio Commission at the time of WFJC Akron, Ohio 227 600 KFKZ Kirksville, Missouri.., 225 15 W F KB Chicago. Ill. 224 500 K F L V Rockford. Ill. 208 100 going to press; and is subject to changes ordered by the WFKD Philadelphia, Pa 248 50 KFLX Galveston. Texas 270 100 regulating authority after May 10, 1928. WFLA Clearwater, Fla 517 75(1 KFMR Sioux City, Iowa 232 100 W G A L Lancaster, Pa 252 15 KFMX Northfield. Minn 236 500 W G B B Freeport. N. Y 246 150 ,,,, KFNF Shenandoah.Iowa(day) 461 2000 ...... ,,,,,,,.,,,,,, ,, ...... ,, ,.... WG BC Memphis, Tenn 229 15 KFOA Seattle. Wash 447 1000 WGBF Evansville, K H MC Ind 236 250 KFON Long Beach. Calif 242 1000 Harlingen, Tex 236 100 WALK Willow Grove, Pa 201 50 WGBI Scranton, Pa 231 250 KH Q Spokane, Wash 370 KFOR Lincoln, Neb 217 100 1000 WA MD tSt. Patti. Minn 222 5Oí1 WG BS thew York, N. Y 349 500 KFOX Omaha, Neb ... 258 100 KICK Red Oak. Iowa (day) . 322 100 WADI Auburn, Ala 341 1000 WGCM Gulfport, b1199 KJ BS San 222 15 KFPL Dublin, Texas...... 275 15 Francisco. Calif... 245 WASH Grand Rapids, Mich 256 250 WGCP Newark, N. J 268 250 KFPM Greenville, Texas 231 15 (6XAR. 62 meters; 50 watts) WATT Boston,Mass(portable) WG ES tChlcago, KJ R 201 100 Ill 242 500 KFPR Loe Angeles. Calif 232 250 Seattle, Wash...... 349 2500 WBAA West Lafayette,lnd..273 500 WG HP tFraaer, Mich 278 750 263 l Also 105.2 meters: 5 to 250 watts) W BA KFPW Carterville, Mo. 50 K Harrisburg. Pa. (day) . 300 500 WG L tSecaucus, N. .7 294 KKP Seattle, Wash 203 1000 KFPY Spokane. Wash 246 250 15 WBAL tBaltimore, Md 286 5000 WG M Jeannette, Pa 208 50 (7XAB. 105.9 meters. 1011 watts) KLCN Blytheville, Ark. (day) 280 50 W B A O Decatur, Ill 268 100 WG MS Minneapolis. Minn 246 600 Louis. Mo 234 50 KIDS Independence, Mo 270 1500 W BAP Fort Worth, WGMU New KFQA St. KLS Texas 500 5000 York,N.Y.(port.) 201 100 KFQB Fort Worth. Texas..., 333 1000 Oakland, Calif 246 250 W BA W Nashville, Tenn 240 5000 (Also 106 meters, 50 watts) K L X Oakland, . KFQD Anchorage, Alaska 345 100 Calif. 508 500 WBAX Wilkes Barre, Pa 250 100 WGN -WLIB Chicago & Elgin, 11141615,000 KFQU Holy City. Calif 220 100 KLZ tDupont. Colo 353 1000 WBBC Brooklyn, N. Y 227 WGOP Flushing, N. K M A Shenandoah, 500 Y 200 100 (Also 31. 53. 03. 106 meters. 50 watts) Iowa 395 1000 WBBBBL Va 234 101) WGR Buffalo, N. Y 303 750 217 100 KMBC see KLOS F Q Wash Richmond, WGST Atlanta, K W Seattle, KMED WM tGlenvlew, III "389 5000 Ga 270 500 KFQZ Hollywood. Calif 232 250 Medford, Oregon 270 ' SO W B B P Petoskey. Mich 240 100 W G W B al liwaukee. Wis 270 250 (Also 108.2 meters. 50 watts) Kra IC Inglewood. Calif 224 250 WBBR Rossville, N. Y 250 1000 WG Y Schenectady. N. Y... +880.50,000 KFRC San Francisco. Calif 454 1000 KalJ Fresno, Calif ... 366 50 WBBW Norfolk, (Also on 31.4, Km MJ Va 236 100 21.96, and sometimes KFRU Columbia, Missouri 250 500 Clay Center, Neb..... 286 250 W B B Y Charleston, So. Car 250 75 5 meters) KFSD San Diego, Calif 441 600 WBBZ Chicago, Ill. (portable) 204 10(1 WHAt- Madison, Wise 333 KMOX Louis, Mo 300 750 KFSG Los Angeles, Calif 252 500 St. 5000 WBCN Chicago, Ill 288 500 WHAD Milwaukee. {C tee 1 0 500 (Also WBES WHAM Rochester, (Has short-wave transmitter) KMTR Takoma Park, Md 265 100 N. Y 280 5000 KFUL Galveston. Texas 258 500 Los Angeles, rlxytrsCalif .516 500 WBET Medford, Mass 288 500 (Has Colorado Spgs.. Colo 486 100) 108.2 meters; 250 watts) WBIS See WNAC tCarlstadt,lsttausm1U2WHAP J KFUM KN RC (Also N. 36 1000 KFUO 'Clayton. Mo 515 1000 Santa Monica, Calif 375 500 W BM H Detroit, Mich 211 100 WHAS Louisville, Ky 322 500 KFUP Denver. Colo 227 Inn (Also 108.2 meters; 100 watts) W B MS Union City. N. J 200 100 WHAZ Troy, N. Y. (Monday) 306 500 KFUR Ogden, Utah 22r 60 KNX Loe Angeles. Calif 337 500 W B N Y New York, N. Y 236 500 WHB Kansas City, Mo 341 500 208 50 (Also 107.1 meters; 100 matte) weoQ Richmond WHBA OII KFUS Oakland, Calif. KOA Hill, N. Y 309 500 City, Pa 261 10 KF UT Salt Lake City, Utah 250 50 Denver, Colo "326 5000 W B O W Terre Haute, Ind.... 208 100 W H B C Canton, Ohio 236 10 KFVO Venice, Calif 216 250 KOAC Corvallls.Oregon (day) 270 7000 WBRC Birmingham, Ala W HBD Beilefontalne, O KO B 303 250 222 100 (Also 105 meters. 50 watts) State College,New Mex :395 5000 WERE Wilkes Barre, Pa 250 100 W H B F Rock Island. III 222 100 K FVG Independence. Kan 225 SO KOCH Omaha, Neb 258 250 WBRL Tilton, N. H 232 WHBL Sheboyan 0018 204 KOCW Chickasha, Okla 252 250 500 250 KFV I Houston. Texas 238 50 (1XY, 105. 109 meter, 250 watts) WHBM Chicago, Ill. (portable) 201 100 KFVS Cape Girardeau, blo 224 0 ROIL Council Bluffs, Iowa 31!) 5000 WBRS Greenville, N. W H B P Johnstown, Pa 229 (9XU, 61.06 500 watts) Y 211 250 250 KF W B Los Angeles. Calif 353 1000 meters, WBSO Wellesley hills, Dials 384 100 W H B Q Memphis, Tenn 232 100 (Also 105 and 40 meters. 50 watts) KO IN ttortland, Oregon 319 1000 WBT W H B U Anderson, KO MO Charlotte, No. Car 25R 1000 Ind 220 16 K F W C Ontario. Calif 243 100 Seattle, Wash 309 1000 WBZ t8pringfeld, Mass 333 15,000 W H B W Philadelphia. Pis 220 100 KFWF St. Louis, Mo 214 230 KOOS Eugene, Ore 207 50 (Has short-wave WHB Y West De Pere, Wis 250 50 KORB Eugene. Ore., 200 50 transmitter) K F W I San Francisco. Cal 208 590 WBZA Boston, Mass 333 500 WHDI Minneapolis, Minn 240 500 K F W M Oakland, Calif... 236 500 KO W Denver, Colo 219 250 WCAC Mansfield, WHEC- WABO Rochester, N. Y. 254 KPCB Seattle, Wash 231 100 Conn 535 50) 250 KFWO Avalon. Calif...... 300 250 WCAD Canton, N. Y 244 500 WHFC Chicago, Ill 216 200 KPJM Prescott, , 15 (Also 53.07 meters, 100 watts) Aria 214 WCAE Pittsburgh, Pa 401 500 W H K Cleveland, Ohio .. +265 500 KFXD Jerome, Idaho 204 015 KPLA Los Angeles, Calif 288 500 WCAH Columbus, Ohio 234 (Also 66.04 meters. 500 watts) K P N P Muscatine. Iowa 211 100 250 KFXF Denver. Colo.....: 283 250 WCAJ Lincoln, Neb. (day).. 380 500 W H N New York, N. Y 395 500 KPO San Francisco, , 422 1000 KFXI tEdgewate °,Colo.(near)210 50 Calif WC A L Northfield, Minn 286 500 WHO Des Moines, Iowa 535 5000 City. Okla 224 50 KPOF Denver, Colo. 201 500 WC A M Camden, WHPP Englewood. 10 KFXR Oklahoma KPPC Pasadena. N. .I 224 500 N.J 205 KFXY Flagstaff. Ariz. 205 Calif WCAO Baltimore. Md 244 250 WHT tChlccaaggo, Ill 306 5000 Tex 211 100 KPRC Houston. Texas 294 1000 W LAD Philadelphia, KFYO Breckenridge. KPSN WC AP Asbury Park, N.J 240 500 Pa 288 100 KFYR Bismarck, No. Dak 250 4250 Pasadena, Calif 310 d000 WCAT Rapid City. So. W IAS Ottumwa, Iowa (day) 322 100 K QV Pittsburgh, Pa. 270 500 Dak 248 100 KG Spokane, Wash 261 2000 W CA U Byberry, Pa 261 1000 W IBA Madison, Wis 240 100 KQW San Jose, Calif . . 297 500 KGB San Diego. Calif 248 100 WCAX Burlington, Vermont 254 100 W IBG Elkins Pk..Pa.(Sund'ys)441 50 (Also 65.18 meters) KRAC Shreveport, La. 220 50 Carthage, WIBJ Chicago, III. (port.) 201 100 KRE Berkeley, Calif. 231 100 III 2550 50 KG AR Tucson, Ariz 234 100 WC BA Allentown, Pa r 2 100 WIBM Chicago, Ill. (port.) 201 100 KG B U Ketehikan, Alaska 400 500 KRLD Dallas. Texas .... 461 500 W C B D Zion, W !BO t Chicago. Ill 306 KRSC Seattle. Wash 273 Ill if34il 5 5000 5000 KGBX St. Joseph, Mo 288 100 50 W C B E New Orleans, La 227 W I B R Steubenville. Ohio.... 250 50 KSAC Manhattan, Kansas 333 1100 250 KGB Y Columbus, Nebraska 222 50 WC B M Baltimore, Md 225 100 W I BS Elizabeth, N..1 204 250 KGBZ York, Nebraska 213 10O KSBA tShreveport, La 208 1000 W C B R Providence, WIBU Poynette, WI 217 20 KSCJ Sioux City, Iowa 244 500 R.I.(port ) 201 100 K G C A Decorah. Iowa. 248 10 WCBS Springfield, Ill 210 250 W I B W To'teka, Kan. 204 250 KGCB Oklahoma City, Okla 216 50 KSD St. Louis, Mo 545 500 WCCO WIBX Utica, N. Y 238 KSEI 250 Minneapolis. Minn +405 50(10 150 KGCH Wayne, Nebraska 294 250 Pocatello, Idaho 333 W C D A Cliffslde, W I BZ Montgomery, Ala 231 15 KSL Salt Lake City. Utah 303 5000 N. J 213 250 KGC I San Antonio, Texas 220 2.50 W C F L Chicago, Ill 484 1500 WICC Fiston, Conn 265 500 KS M R Santa Marla, Calif 273 100 W I KGCL Seattle, Wash 231 100 W C G U Brooklyn, N. Y 219 500 L St.. Louis, Mo 258 250 KGCN Concordia, Kansas 208 50 KSO Clarinda, Iowa 227 500 WIOD Miami Beach, Fla 248 1000 KSOO Sioux Falls, So. 210 Also 54 meters. 15f) watts) KGCR Brookings. So. Dak 208 15 Dak 250 WC LB W I P Philadelphia, Pa 349 500 KSTP Westcott, ?than 220 2000 Long Island City, N Y 200 100 KGCU Mandan, No. Dak 240 100 WCLO 'Kenosha, Wise 227 100 WISN Milwaukee, Wis 270 250 KGCX 244 10 KTAB Oakland, Calif 280 500 W I V A Norfolk, Va.. .. Vida, Montana KTAP San Antonios, Texas 229 WCLS oliet, Ill 216 500 .. 210 100 KGDA Dell Rapids. So. Dak 250 W C M A Culver, WJAD Waco, Tex 333 600 KTB I Los Angele, 275 - Ind 261 500 (daytime) 254 1:3 Calif 1000 WC OA WJAG Norfolk, Neb 2826 "250 KTBR Portland, Oregon 229 500 Pensacola, Fla 250 500 KGDE Barrett, Minn 205 50 WCOC Columbus, Miss WJ A K Kokomo, Ind 234 60 KTHS Hot Springs, Ark 500 1000 231 500 WJA M Cedar Rapids, r (ft leo 40 meters 50 watts) WCON Danbury, Conn . 265 100 Iowa 240 250 KGDM Stockton, Calif. l0 KTNT Muscatine, Iowa 256 2000 WCOT Providence. WJAR Providence, R. I 484 500 KTSA San Antonio, Texas 205 2000 R. I. 225 100 WJAS K G D P Pueblo. Colo. . 224 10 Chicago, Pittsburgh. Pa 270 500 San 207 KTUE Houston, Texas 213 W J A X Jacksonville, Fla 341 1000 KG DR Antonio. Texas 15 W Wash WCSH or lMaIne 5000 KGDW Humboldt. Neb 294 100 KT Seattle, 395 1000 ill WJAY Cleveland, Ohio.. 227 500 KUJ Seattle, Wash 200 10 (also 63.79 meters, 250 watts) KGDY Oldham. So. Dak 207 15 WCSO Springfield, Ohio 25fí 500 WJAZ. tMt Prospect. Ill 263 5000 KGEF Los Angeles, 263 KUOA Fayetteville, Ark 297 1000 WJBA Joliet, Ill 248 50 Calif 1000 KUOM Missoula, Mont 461 500 WC W K Fort Warne, Ind 214 250 KGEK Yuma, Colo. (day) 263 to wr.x P ee WJR WJBB Sarasota, Fla 238 250 EN KUSD Vermillion. So. Dak 484 250 WJBC LaSalle. Ri 227 100 KG El Centro, Calif 225 100 KUT Austin, Texas 212 500 WDAE Tampa. Fla 255 560 KGEO Grand Island, Neb 202 100 W DA F WJBI Red Bank, N..5 263 250 KV I Tacoma, Wash 2e1 250 Nansa Cite, Mo 370 1000 KGEQ Minneapolis, Minn 204 W DAG WJBK Ypsfant'. Mich.. 2203 15 50 KVL Seattle. Wash 273 101 Amarillo. Texas 263 1000 WJBL Decatur. KGER Long Beach, Calif 216' Inn W D A H FI Paso. III 213 250 KVOO Tulsa, Okla '119 500) Texas 234 100 WJBO New Orleans, La 263 100 KGES Central City. Neb 204 10 Wash 2110 KVOS Bellingham, 210 WDAY Fargo, No. Dakota 545 250 WJBT Chicago, Ill. 389 500 Allow ad higher daylight power, Standard or constant-frequency transmic,ton. t Remote Control. (Continued on 7)age 53)

www.americanradiohistory.com Radio News for July, 1928 How the Radio Public is Being Fooled

Number Two of a Series of Articles Exposing Exag- gerated Claims and Unfair Selling Methods in Radio

EVERY industry is continually har- In addition to this, the circular tells you assed by its own fakes and swindles. how to get one of the fanions Leppert The radio industry, during the past IN the June issue of RADIO NEWS "Kleer -Tone" outfits free. This is how it four or five years, had had within appeared an exposure of a "gyp" works out: its ranks a considerable number of firms of radio store and the shady methods em- the "fly-by- night" variety, who have preyed ployed to rope in purchasers. This THE ROAD TO WEALTH upon the gullible and who have macle it all article describes a device extensively "Now is the time for action. Now, if the more difficult for the legitimate manu- advertised in exaggerated terms; it is ever! Here is my FREE TRIAL OFFER facturers to do business. Every time a but one of many. Our readers are in- and my MONEY-BACK AGREEMENT: swindle is perpetrated upon the public, the vited to co- operate by sending in, for Fill out and mail the enclosed card. Send public loses confidence and, after a while, investigation by laboratory tests, ad- no money. Right away we will send you it becomes increasingly difficult for a legiti- vertisements which do not seem to be two Geppert Kleer- 'l'ones-one for your mate firm to prosper. trustworthy. -EDITOR. own radio, and one to start you on the big RADIO NEWS in the past has taken pains to money- making thrill of your life. expose a good deal of radio merchandise "Pay the postman for only one Kleer- which was designed only to pry away some 'l'one -the other is FREE. Sell the extra but it seems extra dollars from set owners; Co., Hewitt _Building, lies Moine:., Iowa). Klcer -Tone to your nearest neighbor, and that there is an unending procession of such "Better Radio from any set instantly" then your own won't cost you a penny. material and RADIO NEWS feels it a continu- "Remarkable invention, ends interference, reduces static a new way" Money Back if Not Delighted "It offers agents an amazing opportunity "Furthermore, I guarantee to refund your to earn $150 to $300 a week" money if you arc not satisfied and delighted. "Big quick cash" That's how marvelous the Leppert is! 'l'hat's "Now the final answer to imperfect radio what I think of it, and that's how 1 stand reception" back of it. "Amazing invention improves reception of any set instantly -almost beyond belief" Refund Plus 50e "Reduces static; sends interference to the "If you don't feel satisfied, return the vanishing point" Geppert within 10 days, and l'li refund The following statement, displayed promi- your deposit and pay you a half dollar extra nently- in box copy, says: for your trouble. So you see I am the only "Sec what it does: one who can lose, if the Geppert does not more than meet your expectations. There (1) Eliminates 50 to 90% of Static. is only one thing to do, and that is to act (2) Increases Volume. now. (3) Brings in More Distant Stations. (4) 'l'unes out Powerful local Stations. Mail the Card Today The outward appearance of the "Meer Tone" (5) Gives your Set at Least One More "This offer is limited. is radio cure -all. trial It strictly Stage. introductory and only for the purpose of (6) Separates Low Wave Length Sta- advertising, and naturally cannot he con- ing duty to expose false pretences ruthlessly, tions. tinued indefinitely. Sit down now and mail in order to protect the public from get -rich- (7) 30 to 40% on Batteries." (Continued on liage 74) quick devices, which often do only harm and Saves in no case accomplish anywhere near what their sponsors claim for theta. We have today, for instance, the note- worthy Leppert "Kleer-'Pone ", which rias been advertised in quite a few mediums and has even been accepted by radio publi- cations that ought to know better. A great many of the readers of this magazine have asked us as to its value and the truth of the claims made for it. The device in question consists of an in- nocent- looking round box, as shown in our illustration. It measures about four inches in diameter and about three inches in height over all. Upon dissecting it in the RADIO NEWS Laboratories, it was found to be an e ordinary radio -frequency transformer, the secondary of which is tuned by a variable condenser. There is nothing else contained in the device, either within or without, yet listen to the exorbitant claims made by the manufacturers.

A RADIO CURE -ALL

The following is taken verbatim from a This is the wonder- working device from the inside. It is a tuned coil, otherwise known as a wavetrap. If advertised and sold os such, no exception could be taken to it, except that the circular (published by The Leppert Mfg. quality is not high compared to the price.

www.americanradiohistory.com 30 Radio News for July, 1928 Radio Aerials Create No Lightning Hazard

Laboratory Experiments with High Voltages Create Thunderstorm Conditions and Show That Lightning Does Not Leave Its Path for Aerials

By Baron Manfred von Ardenne (Berlin, Germany)

IT is a phenomenon well -known in me- face, even in good weather, when there is feet in length; but this is insignificant com- teorology, that the atmosphere in its no sign of a storm. If we take this as a pared with the distance separating it from various layers exhibits an electrical po- base for our calculations, we will find that the earth. tential increasing with its height above at three miles above the earth there will the earth. This is easily demonstrated by GREAT CONCENTRATION OF VOLTAGE connecting one pole of an electrometer to a device which ionizes the air in its imme- ++ However, the comparatively- trifling volt- diate vicinity; if this device is elevated to +0000+ age mentioned can be enormously increased,

+0 0+ sg+ + a substantial distance above the earth, the +0 0+ if the water -vapor is condensed into drops; electrometer will almost infallibly show a +0 0+ the limit of voltage obtainable depends only potential of several hundred volts. +0 0+ on the rapidity of the condensation, which +0 O+ The increase of voltage with height, in +0 0+ is regulated by the temperature and speed the atmosphere, depends somewhat on the +0000+ of the air currents causing this effect. If, ++ geographical location, as well as the time SINGLE SIZE DOUBLE TRIOLE FOUR as under ordinary fair -weather conditions, CHARGE DIAMETER DIAMETER DIAMETERS of the day and of the year; while the cause EAC 8[HARGES 27 CHARGES 64 CHARGES the condensation is gradual, the electricity is not as yet thoroughly understood, it is FIG. 1 will he dissipated through the sunlit and almost certainly due to radiation from the ionized air, and the voltage of the atmos- sun. (See "Summer Radio Reception" in Every molecule of water with an electric charge phere will be equalized without the pro- RADIO News for June 1926, "Sun Spots and adds more to the voltage of the drop to which duction of sparks. Radio" in SCIENCE AND INVENTION for it juins itself. The voltage increases in direct But if the vapor is suddenly condensed August, 1926, previously referred to in this proportion to the diameter. from a gaseous to a liquid state, so that issue, and "Aerial Electricity and the Solar drops of water are formed, there will be Cycle," in RADIO News for June, 1927, for caused an enormous and instant increase in discussions of this matter.) be a charge of about 700,000 volts on the voltage. The "potential gradient," as it is called, molecules of water -vapor which are always The weight of a single molecule, which has a value often as great as 45 volts for present. Such a voltage is sufficient to is the fundamental unit of water, and can- every foot of height above the earth's sur- produce electric sparks from three to seven not be divided without separating it into

Fig. A is a composite picture, made from a photographic plate loge. The aerials are conspicuously untouched. Fig. B shows exposed to many "lightning" discharges on the miniature roil - how the laboratory dikchorge "forks" like real lightning.

www.americanradiohistory.com Radio News for July, 1928 31

area as the square; consequently the voltage of spheres thus combined will be increased THE question has been often asked, have a direct financial interest in the as the cube root of the number brought to- "Do radio sets draw lightning ?" matter, came very early to that con- gether. See Fig. 1 for an illustration of The obvious reply is that they are clusion. the idea.) less likely to do so than electric flat- In this article, Baron von Ardenne, Then, applying this law to the case of irons, for instance; and the inquiry one of Europe's most famous radio the raindrop above described, we find that the voltage which it lias collected will be which was conducted, into the actual engineers, gives RADIO NEws an ex- about 9.4.x 108 (or 9,4,00,000) times greater records of lightning damage, by RADIO clusive resumé of the results of re- of the voltage on the molecules News three years ago and accom- searches carried out with artificial than that of the water while it was still in the form panied by a $300 prize offer, is in- lightning. This has hitherto been pro- of vapor. If the voltage on the water - structive by the negative results ob- duced in laboratories, with interesting vapor was 700,000, that on the drop would tained. The one or two instances results; but this article details the then reach the incredible figure of more which have been sent us since then, first experiments of this nature made than six and a half trillion volts the instant to radio receivers by light- to determine the effects of aerial in- of damage ihat the chop was formed. A voltage very ning, have been so few, in comparison stallations. The article will be found to the number of homes struck by worth while from the theoretical side; lightning (and a fair share of which and its conclusions will be of practi- must be presumed to have radio in- cal interest to radio set owners -that stallation) that the conclusion is war- a properly -installed aerial is far safer ranted that RADIO DOES NOT than electric -light connections and AC- CREATE A LIGHTNING HAZ- TUALLY DIMINISHES THE RISK ARD. The insurance companies, who FROM LIGHTNING.- EDrroa.

two chemically- different gases, is about 5555 A well -known law of electricity tells us times 10 -25 grains. (This is a short way that the voltage is equal to the total charge of writing a fraction which has 25 figures divided by the area of the surface over to the right of the decimal point, and of which it is distributed. If a thousand little which the first 21 are ciphers.) The weight spheres with identical surfaces and electric This `,nap' shows the arrangement of the little village pictured below. of a raindrop of average size, about one - charges (and consequently the same volt- sixth of an inch in diameter, is about half age) are brought together and combined a grain. That is to say, the drop contains into a large one, the big sphere will have a much less than this would be able to strike 835 times 1018 molecules of water (another thousand times the charge of any of the through the distance between the highest short way of writing 835 with 18 ciphers small ones, but only a hundred times its rain clouds and the earth. after it.) The electric charges of all these surface. Therefore, its voltage will be ten (For sonic further information as to the molecules are concentrated on the surface times greater. (The contents of a sphere nature of the voltages thus formed, the of the single drop. increase as the cube of its diameter; the (Continued on page 78)

Fig. C is one of the few cases where it was possible to get a safe as a lightning rod. Fig. D shows a full stroke on the light- stroke on an aerial. A suitable lightning arrester makes one ning rod of the church tower, behind which is an aerial.

www.americanradiohistory.com 32 Radio News for July, 1928 What Is the Life of a Fixed Condenser?

Why There is Invisible Wear and Tear, on the Inside of This Hermetically -Sealed Radio Component, that Will Finally Destroy It

THERE are very few things more the dielectric is put under a pressure which will finally wear it out in due course of deceptive than a condenser. The swings it, as far as possible, end for end. time. It is the quality of the dielectric average user is inclined to think that These are "molecular" motions, too small material used in the condenser, as well as a condenser is a bunch of metal plates to be seen with a microscope, but they with a knob on one end and a strip of Bake- exist in the dielectric, and raise its tem- lite to insulate it from the panel. All very perature; while loose electrons and other well -but the most important thing about infinitesimal particles work their way finally that tuning condenser is the air between through, producing a "leakage current." its plates; and, in the case of a fixed con- This causes a loss of efficiency in the con- denser, the mica or paper between its strips denser circuit, usually measured under the of metal foil. In fact, the air, mica or rather deceptive title of "A.C. resistance." paper is the condenser; the metal parts FIXED CONDENSERS "WEAR are simply low -loss leads to the dielectric, OUT as we call the insulating material between The strain on the dielectric, in the case the metal plates or strips. of a tuning condenser which uses air in that capacity, is not serious, so ALTERNATE The important function of a condenser far as the LAYERS OF is to store up electricity for a given time, lasting characteristics of the condenser are PAPER AND and to discharge it again. The metal of concerned. Air is still quite inexpensive; TINFOIL a condenser would charge with electricity and the wearing out of the condenser can instantly and discharge instantly; but the be expected to take place first in its FIG. 3 insulating material, or dielectric, of the mechanical parts. I-Iowever, the fixed con- condenser takes time to charge and time denser, with a paper dielectric, is in a little different case. Just because to discharge. That is why a condenser it does not The condenser is made of two long strips of can be used to regulate the frequency of move, light up, or heat noticeably in the tinfoil, spaced by several sheets of thin in- a radio circuit, or to take up impulses from course of its operation, gives no reason to sulating paper, and rolled into a compact mass. an audio or a power circuit. The larger suppose that it is inert. On the contrary, its use or abuse in the matter of applied the condenser, the more effecj iveiy we can voltage, that determines its life. charge the non -conducting material in it, The usual mica condenser employed and the longer it will retain the charge. in TERMINALS INSULATION radio reception is employed at such a low At A in the accompanying figure we have electrical strain, compared with its dielec- represented a condenser of exaggerated tric strength, that it lasts virtually forever; thinness. Between the metal plates are in other words, the wear and tear is infini- particles of non -conducting material. They tesimal. The small mica condenser may will take an electric charge from the metal have a dielectric strength of 5,000 volts; plate adjoining them, bat not instantly. METAL CAN hence an applied voltage of 100 or less The particles of air, or mica, or paper in- volves no appreciable effect on the condition carrying a charge arc at once put under of the condenser. a strain which tends to rearrange them. In the paper or filter condenser, how- Particles of air can move freely; but they WAX ever, it is different. The applied voltage are so good an insulator that it takes a usually approaches close to the safe dielec- long time for a charge to leak across an tric strength of the condenser, air gap; and so that there a high voltage to break it is certain to be real wear and tear. down. The FIG. 2 greatest factor of wear in this instance is When we reverse the current, as at B, the the slow disintegration of the paper charge on the metal plates of used the con- for the dielectric. There is always a cer- denser reverses also; thus bringing a posi- 71u- internal arrangement a of "paper" condenser. tain amount of leakage, or current-flow, tive charge of the metal against negative from one plate to the other plate in charges on the dielectric. a con- Immediately it is the field of a great deal of electrical, denser. This leakage- current singles out every particle of the insulating matter in magnetic and other invisible activities which the weakest spots in the dielectric, and more and more current flows through such parts in the vast spread of dielectric ma- terial. This action is accelerated (since more current means more concentrated heat and increased weakness, while increased weakness spells accelerated current -flow) in 4- + . a vicious cycle. Perhaps if we could see such action under the ultra -microscope, we © © °© © °© © © © © © might observe countless minute sparks AD \ gnawing away at the dielectric at the weak- } f i f '` -1.11%%% est point, and steadily increasing the o opening. 1 -I- The life of a paper condenser is com- parable to that of an incandescent lamp. You expect at least a thousand hours of steady service from a lamp. Yet the first time you use the lamp, it may blow out, because it is defective. Again, if you use a 110 - Fic. I. The alternate charging and discharging of the "dielectric," between the "plates" of the volt condenser, puts a strain on its particles. They assume one position, as at A. and are immedi- lamp on a higher voltage, it will give ately nrrcnelird around by the reversal of polarity, as at B. They break loose from time to time; far more light but will very soon burn out. an the little negative "electrons" pass occasionally from plate to plate, also doing damage. The particles indicated above are, of course, magnified billions of tines. (Confint.od on page 70)

www.americanradiohistory.com 7?adio News for July, 1928 33

A Cheap, Practicable Receiver The Crystal Set

The First Lesson in Radio Work -The Simplest Outfit the Constructor Can Build.

THERE are today many broadcast listeners, the proud owners of five- and six -tube factory -made receiving sets, who boast of having heard Chi- cago or even "the Coast ", but have never had the real thrill of tuning-in a nearby broadcaster on a home-made crystal set. To many listeners, a set using a crystal detector is merely a toy, something for the small boy to tinker with to keep him out of mischief.' As a matter of fact, very good ' results are possible with a properly -designed and constructed set employing a crystal detector. In fact this type of receiver was in general use in radio receiving sets on ships and at shore stations in all parts of the world for a number of years, before the ad- vent of the vacuum -tube detector. At the time crystal detectors came into signals over a greater distance than is pos- device. Its clearness of tone has caused general use in radio, there had been em- sible with a crystal, the vacuum -tube detec- many good set builders to favor its use in ployed for years a number of other methods tor was developed. Today the vacuum tube place of a detector tube in many sets of of detection, all of which were unreliable is used in most of the broadcast receiving three to five tubes, such as the well -known because of their lack of sensitivity and the sets in this country. In Europe and other Interflex and Peridyne receivers. The sec- fact that they required constant care and parts of the world, however, the crystal de- ond reason for the popularity of the crystal attention. tector is even now used in perhaps the ma- in foreign countries is its extreme cheapness jority of sets. There are two reasons for and the fact that it operates without bat- this: the first is that, up to MERITS OF THE CRYSTAL SET a distance of teries of any kind, reducing operating ex- fifteen or - twenty miles, the crystal detec- penses to a minimum. With the advent of broadcasting and the tor will give nearly as strong a signal as The listener located in the immediate increased demand for a means of detection a vacuum -tube detector with none of the vicinity of the larger broadcast stations which would make it possible to receive distortion which is often found in the latter needs nothing more than the parts shown on the diagram, phis an antenna and a pair of head telephones, in order to receive by radio musical programs, weather and stock- market reports, baseball scores and other features of special interest. As stated be- fore, this set can be used with good results FREE up to a distance of fifteen or twenty miles from such stations with excellent results BLUEPRINT and, when an inexpensive set is required and conditions permit the use of an outdoor aerial, the crystal set fills the bill. 'RADIO NEWSi FREE Such a set as described makes an ideal receiver to take to the summer cottage or No. BLUE PRINT.I 57 ARTICLE/ camp; provided, of course, that the camp site is not located too far from the more powerful broadcast stations. It is small in size, requires little attention and, since the A free blueprint of this set is complete in itself without batteries or crystal receiver will be given to other heavy accessories, it can be easily anyone who will call for it at carried with the regular camping equipment. 10- the office of RADIO NEws; or will be mailed anywhere on re- BUILDING THE RECEIVER ceipt of a written request for The parts required to assemble the set it. Ask for Blueprint No. 57. are clearly shown in the full-page diagram. The antenna coupler consists of a primary This rear view of the panel of the crystal set shows how few and a tarts are needed. The lir §t cardboard tube L is held in place secondary winding, both wound with by the wires which pass from it through the panel. their turns in the some direction, on a short

www.americanradiohistory.com 34 Radio News for July, 1928

M N 58 58

_t f Mw =1 . Ì 6 16

8 < I II 2 13" 2 16 ,-- 216 / / / Inl , / I \' 6

_-

_ - -1-- 16t

FIG.1 -THIS DRAWING GIVES ALL NECESSARY DETAILS FOR FIG. 2 - COMPLETE DRILLING LAYOUT FOR MAKING A CABINET FOR THIS RECEIVER. WOOD CORNER PANEL OF CRYSTAL RECEIVER.THE LOCA- POSTS Ix 4X2 INCHES ARE USED TO STRENGTHEN BOX AND TION OF PARTS AND BINDING POSTS IS PROVIDE SUPPORT FOR PANEL SCREWS. THE CABINET IS INDICATED IN DOTTED LINES. PANEL MAY MADE OF WOOD 6 THICK. IT IS St SQUARE AND 212 BE MADE OF CIGAR -BOX WOOD PAINTED HIGH. IT MAY BE ASSEMBLED WITH WOOD SCREWS AND WITH SHELLAC, OR BETTER STILL BAKE- GLUE. LITE OR HARD RUBBER. ALL HOLES 16' DIA.UNLESS OTHERWISE SPECIFIED IN THE CONDENSER Cl IS THE ONLY TUNING CONTROL FOR DRAWING. THIS RECEIVER, AND THE CRYSTAL DETECTOR IS THE SYMBOLS IN PICTURE WIRING DIAGRAM ONLY OTHER ADJUSTMENT. THE AERIAL MAY BE A SINGLE CORRESPOND TO SIMILARLY - MARKED WIRE IOO' IN LENGTH, AND THE GROUND CONNECTION MAY PARTS SHOWN SCHEMATICALLY IN WIRING BE MADE TO ANY CONVENIENT COLD -WATER OR RADIATOR DIAGRAM. NO.24 D.C.C. WIRE MAY BE USED PIPE. NO.14 WIRE MAY BE USED FOR AERIAL AND GROUND FOR MAKING CONNECTIONS, AND ALL WIRES. THE ONLY ACCESSORY REQUIRED FOR THE OPER- JOINTS SHOULD BE SOLDERED FOR BEST ATION OF THE SET IS A PAIR OF TELEPHONE RECEIVERS RESULTS. DETECTOR

ANTENNA CRYSTAL COUPLER /DETECTOR AERIAL D .fr L H AERIAL PHONES C1 C2

GROUND VARIABLE CONDENSER

FIG.4-COMPLETE PICTURE WIRING DIAGRAM FIG 3 - SCHEMATIC DIAGRAM OF CRYSTAL RECEIVER. L, AN- TENNA COUPLER; CI, .0005 -MF. VARIABLE CONDENSER; C2, .00I-MF. FIXED CONDENSER; D, CRYSTAL DETECTOR. A B C D E F

FIG. 6 DETAIL OF' CRYSTAL F!G. 5- DETAIL DETECTOR OF COIL L

LrP G H FITS IN SECONDARY COIL CS) CONSISTS OF 90 TURNS NO.24 D.C.C. A IS THE GALENA CRYSTAL WHICH IN PLACE WIRE ON I2DIA.CARDBOARD TUBE. PRIMARY COILCP) HAS CUP B. CATWHISKER C IS HELD JOINT E MAKES ALL 15 TURNS OF SAME SIZE WIRE ON SAME TUBE. A STAND- WITH CHUCK D. BALL ACCESSIBLE FOR CON- ARD MAILING TUBE MAY BE USED FOR COIL FORM. POINTS ON CRYSTAL TACT. F IS THE ADJUSTMENT KNOB AND G. AND H ARE TERMINALS.

www.americanradiohistory.com Radio News for July, 1928 35 length of cardboard mailing tube or other surely soldered to the end of the aerial The only part which should need 'Occa- suitable coil form, one and one half inches which is nearest to the receiving set, in sional replacement is the crystal, which costs in diameter. The secondary winding S is order to make the lead -in as short as pos- but a few cents and should last a long started five- sixteenths of an inch from the sible; or, better still, a single piece of wire time. There is a great difference between end of the tube. Two small holes about one - may be used for both aerial and lead -in. crystals -as there is, in the sensitivity, be- half inch apart are punched in the tube, at Care should be taken to see that the lead - tween different points on the same crystal. the start of the winding, and the end of in is carefully insulated from all objects It is advisable to purchase only "tested" the wire is passed down through one hole with which it might come in contact, such crystals, which cost but a little more than and up through the other. This serves to as window sills, gutter pipes or the side of the general run of specimens, and are well tie the end of the wire. About six inches the house. worth the difference. of extra wire should be left at the start of If the receiving set is to be located in There are many different kinds of miner- the winding to serve as a connection. Hav- the city, an excellent ground connection may als beside galena and silicon which give the ing securely anchored the end of the wire, be secured by fastening a ground -clamp detecting action of the crystal, and, when you may wind ninety turns (of No. 24 around a convenient water or steam pipe, radio was younger, experimenters spent double- cotton -covered wire) firmly and first making sure that the connection is free nmch time working with different com- smoothly on the tube. Two more small of paint, scale, etc.; so that good metallic binations. The builder of this set, if he is holes are made at the end of this winding, contact will he obtained between the pipe where strong signals may be heard, may and the wire is passed through them, in and the clamp. If no water or steam pipe derive considerable amusement from a little the sane manner as at the start of the coil. is available it will be necessary to make work of this kind. The detection, it may A space of one- eighth of an inch should some other kind of ground connection. A be explained, is due to the fact that the then be left and two more holes are made number of short lengths of pipe, three or current in the crystal circuit can pass much in the tube, through which can be passed four feet each, may be driven into the more freely in one direction than in the the start of the primary coil P. This should ground at a convenient point and all con- other; and the alternating "signal" wave is consist of fifteen turns of the same wire, nected together by a wire leading from thus converted into the small direct cur- wound in the same direction as the second- them to the "ground" binding post on the rent needed to work the diaphragms of the ary. A short length of wire should be left receiving set. telephone receivers. This action may be at the start and finish of this winding also, obtained between two fine points of any for connection to the other parts of the set. THE LIGHTNING ARRESTOR conductor which touch each other over a If the set is to be installed permanently very small area; but such apparatus is OTHER PARTS at your home or cottage it will be well to generally of too delicate a nature to be The most expensive part required in the install some form of approved lightning undertaken in the home. Detection between construction of the set is the variable con- arrestor. This should be mounted on the two steel balls, and other metal surfaces, denser. This should have a capacity of was described in RADIO NEWS for Septem- .0005 -mf. and should be of "low- loss" type; ber, 1927 ( "Rectifying with Metallic De- that is, have good insulating material, not ADVICE TO PARENTS tectors") and old- timers in radio will re- too large, and be of substantial construc- that boy is interested in radio, a member many very interesting devices with tion. Any fixed condenser of good quality IFgood way to keep him out of mis- which they used to tinker -such as platinum may be used for the phone condenser; chief is to start him in where his old wire and mercury, razor blades and carbon however, the one selected should have a man started -building his own. This rods, etc. The set builder of today, how- capacity of at least .001 -mf. little set costs little or nothing, and ever, will hardly go so far into experi- The other parts required to assemble the will bring in the locals -and it will mental work. set are four binding posts, a few short give the young constructor an insight lengths of wire for connections and the into doing things for himself. OPERATION IS EASY detector device. The detector shown in the When the receiving set has been com- illustration uses a galena crystal, but silicon pleted and all necessary connections made, can be employed with results nearly as good. outside of the house at a point just above including the aerial and ground, the knob The galena crystal is the more sensitive of where the lead -in enters the wall. The F which adjusts the catwhisker should be so the two but requires a little more care in lead -in wire is then brought to the top of placed that the end of the spring wire C adjustment than does a silicon crystal. 'l'he the arrestor and from there to the aerial rests lightly upon the surface A of the crystal used may be purchased in either the binding post on the receiving set. The crystal. (See Fig. 6.) The variable con- mounted or unmounted form. The mounted lower connection on the arrestor should denser should then be turned slowly back crystal is shown in the illustration; this will then be connected with the ground. and forth from one end of the scale to the give the best results and costs but little The success of this type of receiving set other until a station is heard. if no station more than in the unmounted form. In depends to a great extent upon the aerial is tuned -in, and you are sure that a station handling the crystal care should be taken to and ground and the crystal detector. The in your vicinity is broadcasting at the time protect it from dust and moisture and it higher the aerial the better, provided that you are listening, the catwhisker on the should be handled as little as possible. The the lead -in sloes not exceed fifty or sixty detector should be readjusted and the con- surface of the crystal should never be feet. If the ground lead is connected to a denser turned as before. At first it may touched with the fingers if this can be water pipe and care is taken to see that the be necessary to repeat this operation several avoided,- as the oil from the skin tends to pipe is well scraped before the ground times until the operator locates a sensitive make the crystal less sensitive. clamp is applied, the ground connection spot on the crystal. After having located The layout for the panel is given in Fig. should be abort as good as is necessary for the most sensitive spot on the surface of 2, the location of the parts and binding the average receiving set. the crystal, the operator can usually read- posts being indicated by the dotted lines. just the detector from day to day with but The panel may be made of cigar -box wood ACCESSORIES little trouble. Patience, of course, will at or, better still, of bakelite or hard rubber. The only "accessories" required for this many times be needed. A plain three -inch dial is required, and set are a pair of headphones, which may be In the crystal sets sold extensively in should be securely fastened to the shaft purchased at from two dollars up to, say, Europe, the detector is often furnished in a of the variable condenser after the con- ten dollars. A good pair will be found an glass tube, or other cover to protect it from denser is mounted on the panel. This is excellent investment for the experimenter; dust, moisture and disturbance. The builder the only tuning control for this receiver. as they can be used with larger sets, when of this set is not apt to go to so much built, for "distance work" in radio reception, trouble; as before long, probably, he will THE ANTENNA SYSTEM and are, furthermore, useful in the work- consider the two-tube "Extension" receiver The aerial may be a single length of No. shop for testing radio parts (with the aid described in this department in the May 14 bare copper wire and, if possible, it of a small battery). It is therefore advis- issue of RADIO NEWS, or some similar set, should be 100 feet in length; although this able to get as good a pair as you can afford, on which to exercise his ingenuity. Ht. w- can be changed slightly to fit local condi- as it will add considerably to the satisfac- ever, should this set remain in use for any tions. The aerial may be strung between tion obtained from all future radio work. reason, it will perhaps be found necessary two convenient trees, the roof of the house As the energy in the circuit of the crystal to clean the crystal. Alcohol or some and a near-by tree, or any other suitable detector is small at the best (unless you are similar fluid which will evaporate completely support. An insulator is required for each very close to a station) the sensitivity of the should be used; and the crystal, as we said end of the aerial. The lead -in, from the phones is important; they should be of a before, should not be handled with the bare aerial to the receiving set, should be se- resistance of 2,000 to 4,000 ohms. fingers or anything oily.

www.americanradiohistory.com 36 Radio News for July, 1928 A "Junk Box" Short -Wave Receiver* For the Experimenter Who Wishes to Try His Luck Below a Hundred Meters B Robert Hertzberg of the board, and the remaining two on the right edge, near the back. Continue by FEATURES OF THIS SET screwing clown the R.F. choke L2, the R2 THE little short -wave receiver de- transformer Tl, the filament ballasts and R3, the three tube sockets. Sepa- scribed in the accompanying ar- and rate the two sockets on the left enough to ticle possesses the following features. leave room for the grid condenser. which will appeal to everyone: The two sockets at the right are for (1) It will pick up short -wave broad. the one the left acts as a BECAUSE of the extraordinary DX amateur and commercial stations tubes, but at cast, receptacle for the plug-in coils used with work that is being accomplished by between 20 and 100 meters. operating the receiver. Before making up these coils, amateurs and broadcasters on the (2) It may be assembled in two construct the aerial coupling condenser C3, short waves (i.e., below 100 meters), hours. as shown in an accompanying illustration. litany- radio fans have become possessed of (3) Its cost is practically nothing; This condenser has a very small capacity, the idea that the apparatus used for such as the necessary parts may be found and its adjustment is not at all critical. reception must necessarily complicated, in almost every experimenter's junk expensive, and difficult to construct and Any arrangement for separating two pieces box. of brass or copper each one -half inch square operate. These fans read of the success of (4) It is easily operated, as it uses is satisfactory. listeners in South America, Africa, Aus- only two controls and two tubes in up Break the glass bulbs off the five burnt - tralia and New Zealand in picking a simple circuit. programs transmitted on short wavélengths out tubes, and clean the insides of the bases, from Schenectady and Pittsburgh in the removing the connecting wires, bulb stems United States, and from London, in Eng- and cement. If the cement defies removal land; and of the similar success of Ameri- signer of the set guarantees that any read- by ordinary scraping, heat the bases gently can listeners in hearing broadcasts from er who duplicates it exactly will be re- over a gas flame and scrape it out as it England, Holland, Germany, Russia, Siberia warded with more thrills than he has ex- softens. Apply a soldering iron to the and Australia. As a result, they are apt perienced from any other radio receiver In prongs in the bases and melt out all the to conclude that the receivers must con- several years. solder so that new connecting wires may tain at least eleven tubes and be two yards The first thing to do, of course, is to be pulled through latter. If the solder re- long. gather together the necessary parts. You fuses to flow out, push a toothpick through The truth of the matter is that the re- will need the following: each pin while the metal is still soft, and ceivers employed by the majority of these ream the opening clean. Also file off the listeners are of the simplest possible de- One wooden baseboard, not smaller than 1034 by little bayonet -lock pins on the sides of the containing more than three 7 inches and at least l4 -inch thick. bases. sign, rarely sockets. only two. They are of Three 11X-type tube tubes and usually Two 32 -mmf. "midget" variable condensers (so- MAKING THE PLUG-IN COILS the "straight regenerative" type, and can called `verniers" usually used in broadcast IR the receiver with a be made in an hour or so of spare parts, receivers for neutralizing or compensating pur. order to provide and C2. 110 meters, five such as are found in every experimenter's poses). CI wavelength range of 20 to One .0001 -mf. grid condenser and a 3-megohm coils, each a grid ana They enable their owners to will work, hut plug -in containing junk box. leak, (a regular .00025 -mf. size winding, necessary. The tube pick up the programs of numerous short- the smaller condenser is better on the short a tickler are to accommodate the wave broadcast stations, conversations be- waves) ; C4, Rl. bases are long enough One battery switch. SW. of wire for the tween amateurs using voice transmission, required number of turns One R.P. choke coil. (This is important: if you first four coils; but the fifth base taust be and code signals from thousands of ama- haven't a good one on hand. buy one that will will make it teur and commercial transmitting stations work from 20 meters up); L2. fitted with an extension that transformer (anything avail- long. glue a piece in every part of the world. The "thou- One A.F. amplifying about three inches Simply able); T1. and tie it up is no exaggeration; for there are with of cardboard around the base sands" Two 5z- ampere filament ballast resistors, When the wire than 16,000 licensed amateur trans- mountings; R2, R3. with cord until it dries. more tightly in stations in the United States alone, Nine spring binding posts. is wound on it later it will remain mitting tubes with UX-type bases. and large numbers in other countries. in- Five burned -out place. Enough scrap brass to make L- shaped mountings are the specifications of the five ternational communication between these for the two midget condensers and the bat Following stations, over distances as great as there tery switch and for the aerial coupling con coils: can be between two points on this earth, is denser, C3. No. 1: Grid and tickler windings. each 7 turns: a nightly affair. CONSTRUCTION SIMPLE wavelength range, approximately 19 to 25 meters. OUT OF THE JUNK BOX The first thing to do is to make the No. 2: Grid and tickler windings, each 10 turns; For the purpose of illustrating how sim- L- shaped brackets to hold the midget con- range, 25 to 35 meters. No. 3: Grid and tickler windings, each 15 turns: ple an efficient short -wave receiver can be, densers and the battery switch upright. of stiff brass, about range, 35 to 45 meters. a member of the staff of RADIO NEWS se- Select any odd strips 4: Grid and tickler windings, each 22 turns; pieces to form No. lected a handful of idle parts from his own % -inch wide, and bend three range 45 to 64 meters. Tickler wound as double private junk box and assembled a complete L's about two inches high, with legs half layer to save space. legs to pass small No. 5: Grid and tickler windings. each 40 turns; two -tube set in less than two hours' tinte. an inch long. Drill the also double' to pass range. 62 to 110 meters. Tickler He worked a second evening "juggling" the wood screws, and the upper ends layer. various coils, to make them cover the short- the mounting studs of the condensers and coils are all wound with No. 2t from 20 to 100 meters, but the the switch. Screw them clown along the The grid wave bands wire, and the ticklers with No. 28 reader of this article will be spared this front edge of the baseboard, as shown D.C.C. data are ready for him. The clearly in the accompanying illustration. D.C.C. work; all the starting to wind the coils, drill outfit produced such gratifying re- and mount the instruments afterward. Before little of the through each of the bases four small holes that Ramo NEWS decided to publish Now nail or screw down seven sults edge to pass the ends of the windings. 'l'he the following description of it. 'l'he de- spring binding posts along the back

* RADIO Nsts Free blueprint Article No. 58. See page 38.

www.americanradiohistory.com Radio News for July, 1928 e

t c rn

o

PHONES

The connections of the "junk -box" short-wave receiver are shown here in straight lines for clearness; but in the set it- self, as the picture on page 38 shows, they are run as short and direct as possible- especially the aerial and detector leads carrying R.F. energy, because of the high capacitive transfer of energy at ultra -high frequencies. The construe- tor, bearing in mind this rule, may depart from the layout here as the apparatus he has at hand suggests.

www.americanradiohistory.com 38 Radio News for July, 1928 proper places for these holes can be deter- mined from a careful study of the illus- tration on page 39, which shows how the various ends connect to the four prongs in each base. To start coil No. 1, push the end of the spool or roll of No. 24 wire through the hole nearest the open end of one of the bases, leaving a free piece about five inches long. Wind on the required seven turns, cut an extra five inches, and pull the end through the second hole. Start the tickler winding about a quarter of an inch away, and wind in the same direction. Leave generous ends on the wires. It is extremely important that the four loose ends you now have be connected prop- erly to the four prongs. The loose end of the top of the grid winding is pulled through the pin that makes contact with the plate or "P" terminal of the tube socket. The bottom of this same winding is pulled through the pin that makes con- The simplicity of the construction of this receiver is apparent from a glance at the circuit diagram tact with the "F-{-" socket terminal (which above, as well as the pictorial layout on the preceding page. The interchangeable inductance, LI, is should be the one under the "P" terminal wound on an old tube-base, and plugs into the tube socket .seen in the picture belote. opposite the "G" post). and diametrically direct, of the tickler (the end near- the grid leads being especially so. The beginning 'l'he grid condenser need est the grid coil) goes through the other FREE not be screwed clown, as the short filament pin, while the other end goes to lengths of wire con- nected to it will hold the pin. Study the arrangement of it in place. grid The connections in the base, note how they fit into BLUEPRINTS rotor of the midget con- the pins densers and you will have no trouble. are wired together. A short lead the socket, extends After pulling through the wires, solder from Cl to the "F+" post on the coil receptacle, and thence them at the tips of the prongs and cut to the ground binding post; while them flush. No. 58 another lead, from C2, runs two inches The other coils are wound in exactly the to the nearest filament post on the detector-tube same fashion, except that for Nos. 4 and 5 socket, VI. The circuit is of the simplest imaginable the ticklers are wound double layer. The SET of full -sized blueprints for regenerative type, with the wire in all cases may be secured with col- this Short -Wave Receiver, ac- aerial coupled directly to the grid lodion or other prepared coil binders. This companied .by a list of the used tuning coil by means parts of the tiny condenser treatment is not absolutely necessary, but in set and full constructional C3. The wavelength this range of the set depends it will keep the coils in good condition. data, will be given free to any person on the size of this grid coil and the capacity of the tuning applying at the office of RADIO NEws, CONNECTIONS condenser, Cl. Regeneration is made 230 Fifth Avenue, New York City, pos- sible by the tickler coil, connected in series The wiring of the set is so simple, and during business hours, 9:00 a. m. to with the plate- circuit elements, is made so plain in the diagram and the 5:30 p. m. (1:00 p. m. only on Satur- and is con- trolled by large illustration, that little comment need days). On request, the blueprints the other variable condenser C2. be made on it. The letters, "F," "G," "P" will also be sent by snail free of Circuits of this type, when used on the and "F," alongside the coil L1 in the sche- charge; please write your name and regular broadcast band (200 to 550 meters), matic diagram, represent the terminal mark- address clearly. radiate and cause terrible interference in neighboring receivers; ings on the socket which acts as the coil Ask for Blueprint No. 58. but they are not at receptacle. 'l'he connections are short and all obnoxious on the short waves because the average -size receiving aerial cannot readily be shocked into oscillation at wave- lengths as low as 20 to 100 meters.

OPERATION AND TUNING To place the set in operation, connect your regular aerial and ground to the posts provided for them, and hook-up the usual six -volt "A" battery and one or two 45- volt blocks of "B" battery. Run a wire from the 22% -volt post on the first block for the detector tube, and use the full 45 or 90 volts on the amplifier. (Note: A "W' socket -power unit cannot be employed with a short -wave receiver). Push the tip con- nections of a pair of headphones through the two clips on the right hand edge of the baseboard, insert 201A -type tubes in the two tube sockets, plug in coil No. 4 as a starter, and snap on the battery switch. The set should regenerate without trouble when the condenser C2 is turned in slowly. With the tuning condenser practically all in (near maximum capacity) you should he able to pick up KDKA, Pittsburgh, on its 62.5 -meter wave. (This station has what is probably the most consistent short -wave broadcast transmitter in the world.) You should hear it also on coil No. 5 with the All the connections employed in this set are made on top of the wooden baseboard, as may be seen in condenser all out (minimum capacity). the illustration. The capacity, C3, is shown in detail on the following page; it consists of two sepa- ratclymovable metal plates. With coil No. 4 you should also pick up,

www.americanradiohistory.com Radio News for July, 1928 39

The details of one justnlents to rely on in "fishing" for sta- denser C:3 must be found by trial; it will of the plug -in coils on used in the "junk - tions other waves. depend on the dimensions of the individual box" short - wave For handy reference, cut out the list of aerial. Likewise, different, values of the receiver, which is built up on the stations printed on page 1175 of the April grid leak should be tried. base of a burnt - number of RADIO NEws, and those listed on out UX -type tube. 60 This is large page of this issue. All these stations, enough to g iv e with the exception of a few, use voice room for the tick- transmission be ler winding T and regularly, and can picked the aerial- second- up with this little receiver if you "fish" for ary S, of suitable them carefully and learn how to adjust the sise to be tuned by a 32 -mmf. con- two midget condensers. By the way, dis- denser (Cl) up to regard the coil numbers mentioned in the 64 meters. Above this it is necessary April list; they refer to another receiver, to add a cardboard with but three sets of coils. extension to the base to increase its To obtain smooth control of the regen- height. Details for eration is a simple matter. Each coil, when the five sires of coils will be found the tuning condenser CI is set at maximum, on the first page should start oscillating just as the other of this article. The connections, shown condenser, C2, is turned to maximum. If in plan at the bot- the set oscillates before maximum position tom, arc as fol- lows: top of grid is reached, remove one turn at a time from rcinding to "P" the tickler winding until this operating con- prong; bottom of grid winding to dition is attained. The ticklers specified '"F + "; for of tick- earlier in this article will probably be ler (T) to "F -"; bottom of tickler to "G.» found too big, and will produce oscillation TOP VIEW with only part of the regeneration condenser Above, a side view of the midget tuning con- without delay, the signals of WLW, on 52 in use;, but they are purposely designed denser Cl. One lead runs to the top of the meters. With coil No. 2 and most of the large, because they can be cut down very grid winding S and to the aerial condenser C3, formed by the small adjustable plates shown in condenser in, WGY, on 32.77 meters, should easily to suit the operating characteristics the top and side. Tinos. Its adjustment for the roll in nicely. Once you hear these stations of different tubes. aerial used must be determined by experiment. The two opposed surfaces arc about one -half you will have some definite condenser ad- The best adjustment for the aerial con- inch square.

A. C. Tubes Require Special Wiring Care

ONE of the most troublesome causes of fire clue is to insert a 0.1- megolun (100,000 - transformer mentioned and the cathode "hum" in a receiver which employs ohm) fixed resistor in the grid -return lead terminal of the detector tube. (See Fig. 1.) A.C. tubes is interstage coupling in the between the "F" terminal of the R.F. trans- Another precaution to keep the hum down parts of the circuit which are common to former secondary of the detector circuit and to an absolute minimum when using a 227 - both R.F. and detector circuits. the grid- biasing resistor which provides the type A.C. tube as a detector is to connect When the location of the parts of the set bias for the R.F. and detector circuits. A the center -tap of its 21/2-volt filament- supply is properly planned, and the wiring care- 0.1 -mf. by -pass condenser should then be transformer winding to the "B+ Det" tap; fully arranged and cabled to avoid coupling connected between the "F" terminal of the thus placing a bias of from 221/ to 45 volts between the heater filament and the cathode. (See Fig. 2.) In Fig. 2 at the left, the The 227 -type A.C. tube is very free from heater filament R.F. 1 AF is 45 microphonic action and does not require volts positive with regard to the cathode, from Which the special treatment or mounting usually it is electrically insulated; necessary in the case of microphonic de- this is one way to mini- mize the transfer of cur- tector tubes. rent hum to the cathode. In Fig. 1 are the con - LARGER WIRE NEEDED nections mentioned in the text. Terminal Y may One of the most important things to connected to either lfy watch, when using the new A.C. tubes or X; trial will show which. provides the best of the 226 and 227 types, is to make sure results. 'D is the R.F. that the wire used for the connections to the grid- biasing resistor, often a 400 -ohm potentiometer; filaments is heavy enough to carry the re- B+45 B+45 A ant B the X.F. and quired current. detector filament center taps. In using tubes of the 201A, 112A, 171A, FIG. a (Continued on page 69)

effects, no trouble may be expected from R F. DET 15T A.F. "hum." In many cases, however, the limita- tions of space and the necessity for crowd- ing parts together will introduce "loops" and coupling effects in the wiring. The use of the grid -condenser- and -leak arrangement for the detector, while highly efficient and sensitive, very often makes the field surrounding the detector portion of the receiver very critical and unstable. If any trouble is experienced from that source, it is usually best to change the detector to the grid -bias method. 0.1 MEG. A SIMPLE FILTER In the event that this change does not eliminate the coupling which causes "hum," a simple method which is practically a sure- FIG.1

www.americanradiohistory.com 40 Radio News for July, 1928 A Sturdy and Dependable "B" Power Unit

Especially Designed for Use with the "Neutroheterodyne" Receiver, and Readily Adaptable to Any Large Set

Free Blueprints

No. 59

A set of full -sized blueprints for this "B" and "C'' power-supply unit, accompanied by a list of the parts used in this device and full construc- tional information, will be given free to any person applying at the office of RADIO NEWS, 230 Fifth Ave., New York City, during business hours, 9:00 a. in. to 5:30 p. in. (1:00 p. w. only on Saturdays). The blueprints will also be sent by mail free of charge; please write or print your name and address clearly, as signa- tures are often illegible. Ask for Blueprint No. 59 for the Neutroheterodyne power unit. Fig. B. The exact position of all parts mounted on the baseboard is shown in this top view of the power unit. Tl, power transformer; VI, tube socket; LI and L2, fitterchoke coils; L3, detector 'B" choke coil; L4, output choke coil; Cl, C2 and C3, filter condensers; R6, R7 and THE "B" socket -power unit described R8, fitted resistors; Rl, R2, rheostats; R3, R4, grid -bias resistors; RS, "B+Det." control. in this article was designed especially for use with the seven -tube Neutro- as possible; therefore, it may be used satis- directly from any standard 110-volt, 60- heterodyne receiver, which was de- factorily with most large receivers of similar cycle source of power. It provides a maxi- scribed on page 1336 in the .June 1928 issue design. mum plate potential of 350 volts for the of RADIO NEWS. However, its designer was Briefly, this power pack may be described operation of a 210 -type power tube in the careful to make the apparatus as flexible as a "B and C" supply unit which operates last audio stage and, in addition, it gives a grid-bias potential of 25 volts for this tube. The unit also delivers various inter- mediate values of grid and plate potential for operating the other tubes of the re- ceiver, as well as 8 volts A.C. at 2% am- peres for heating the filament of the power tube. The maximum total D.C. output of the unit is 60 milliamperes at 375 volts, when using a rectifier tube of the type recom- mended in the list of apparatus. The illustrations on this page clearly show the constructional features of the power pack. All of the apparatus is compactly assembled on a wooden baseboard 11 by 17 inches, and the controls are mounted on a vertical bakelite panel 7 by 18 inches. It will fit easily into any console base.

CHARACTERISTICS In circuit design the power unit under discussion is not unusual, but several in- teresting features have been incorporated in the wiring. From the diagram it may be seen that the power is supplied by a single power transformer with three secondary windings. One of the latter provides the high voltage for the rectifier, and the other two windings are center -tapped and each has an output of 8 volts at 2.5 amperes; one is used for heating the filament of the Fig. C. The appearance of the power unit when viewed from the rear. The symbols shown power tube and correspond to those used in the text, list of parts and other illustrations. the other for the rectifier.

www.americanradiohistory.com 'Radio News for July, 1928 41

The builder of this unit has a choice of The filter circuit of the power unit is SPECIAL CHOKES INCLUDED rectifier tubes. The unit was originally de- standard. It employs two A.F. choke coils An interesting feature of the power unit signed for operation with a tube of the connected in series and three filter con- is that the loud -speaker filter coil is 21611 type, but it may also be used in con- densers connected at various points across mounted in the power unit rather than in nection with the new 281 -type rectifier. the line. The two audio -choke coils of the the receiver. This piece of apparatus oper- When the 216B -type tube is used the out- filter circuit have a total resistance of 1,200 ates with equal efficiency in this position, put voltages shown in the diagram are ohms, a maximum current -carrying capacity and in this way it is possible to remove a obtained; the voltages obtained from the of 60 milliamperes and a maximum induct - large and heavy piece of apparatus from 281 -type tube are slightly higher, but the tance of 50 henries each. The chokes have the receiver. The 4-mf. by -pass condenser, increase is not sufficient to make necessary another feature which makes possible high- which together with this audio choke coil any other changes in the unit. Both the est efficiency; namely, an adjustable air comprises the loud- speaker or output filter, 216B- and 281 -type tubes are half -wave pap ira the core. After the power unit has is mounted in the receiver cabinet. Another rectifiers and each requires the saine fila- been connected to the receiver the air gap piece of apparatus mounted in the power ment current. Therefore, in most cases of each choke coil may be adjusted and pack is the choke coil connected in the they may be used interchangeably. How- in this way the A.C. huas of the output is plate lead of the first -detector tube (see ever, the latter tube has a greater current - greatly reduced. The adjustment of the the previous Neutroheterodyne article); carrying capacity and a lower resistance, air gap gives the choke the highest possible this coil is not needed with all types of with the result that it is possible to obtain inductance under any operating conditions. receivers, but is required for the operation a greater output under the same conditions The three condensers used in the filter cir- of a superheterodyne of the type this power without overloading. cuit re units of 4 mf. each. unit was designed to supply.

A- -C AMPL. FIL. 8-TAP D-E-F RECT.FIL. E- T1

IIIIIIIIIIIIIII;IIIIIIIIII -c)l 1111111111111111611111111' r 'Illlllllllilllllllllllli

11 L iÌÌÌÌÌIIIIIiìiùlilll Ilii;11!1IIIIIIIIIÍIII IIImm111111111111II h

IQ IIIhIIIO1E1uuuri I I ITIII IIIImIIuIluI ;giplllilllllllll ,r, IIIIIIIIIIIIIUUpT -21_ aumuUlÌlìiìlilüïu; uiiuiullmumuiiifl - f cmnulllmuuuuull

Fig. 2. When building the power unit, the constructor should mark out each wire with lead pencil on this diagram after the connection has been completed, thus insuring greater accuracy in wiring.

www.americanradiohistory.com 42 Radio Newts for July, 1923

VARIABLE VOLTAGES 18" In the resistance bank of the voltage - dividing potentiometer, both fixed and vari- able units are employed. Two fixed re- -3" sistors connected in series are employed 4 reduce the potential from 350 volts to to - 3' 3' 90 volts, the value required for the opera- V2ORIIL' tion of the amplifier tubes of the receiver. FOR R2 v2 DRILL 42 ORILL FOR R3 FOR P4 The resistor which causes the potential to 3i DRILL FOR R5 drop to 45 volts for the operation of the two detector tubes is a variable unit; and two other variable resistors are employed %l DRILL AND COUNTERSINK FOR FLAT HEAD HOLE FOR 4 HOLES. MHr for obtaining the two values of grid bias WOOD SCREWS. '1 N SNAP SWITCH DRILL SW. v2 which are required. In addition to these FOR RI _,T two resistors, two rheostats are used to

control the filament voltages of the rectifier t 1 and power- amplifier tubes. 5' 5' '3 '- .

SPECIAL FEATURES Fig. 3. This diagram shows the exact positions and dimensions of all holes required in the front panel for mounting the various parts shown in the pictures. In the first paragraph of this article it has been stated that this power pack was designed especially for the "Neutrohetero- transformer is used in place of the loud- at even distances, on a line slightly below dyne" receiver, but that it may be used speaker or output filter. the center of the panel. 'l'he knob at the successfully with other receivers employing The illustrations on these pages clearly left (R3) is for regulating the grid poten- approximately the same number of tubes. show the construction of the power pack. tial applied to the power tube; the knob Before describing the construction of the The picture reproduced as Fig. A indi- in the center (R4) is for regulating the unit, it will be explained which features cates the arrangement of controls on the bias applied to the amplifier tubes of the apply especially to the Neutroheterodyne; front panel, and from this view of the unit set, and the knob at the right (R5) is for as these need not be incorporated in the it may be seen that there are six adjust- adjusting the detector voltage. power pack if it is to be Used with another ment knobs. 'I he switch for turning the receiver. power on and off, and for regulating the ASSEMBLY In the first place, it will be noticed that input to the unit, is located at the extreme the diagram calls for wires of eight dif- left of the panel at SW. This is a standard The arrangement of parts mounted on ferent colors in the output circuit. These snap switch with one "off" position and the baseboard of the power unit is shown colors are the saine as those used for cor- three "on" positions. It is mounted on in Fig. B. When looking at the unit from responding wires in the "Neutroheterodyne" the case of the power transformer, and it the rear, the power transformer (Ti) will receiver; but the color code should be will be necessary to cut a large hole in be seen located in the front right corner adapted to the receiver with which it is the control panel to make possible the ad- of the baseboard in such a position that to be used. Secondly, the audio choke in justment of the knob from the front. the key of the snap switch protrudes the plate- supply wire to the first detector The knobs R1 and R2 are arranged, one through the hole drilled in the front panel. is not needed with the average receiver; but above the other, slightly to the right of At the rear edge of the baseboard, directly it is essential for the operation of the "Neu- the switch. 'l'hese knobs control the ad- behind the power transformer, the tube troheterodyne." Thirdly, in a large num- justment of rheostats which regulate the socket (ßr1) for the rectifier has been ber of cases, it will be unnecessary to mount filament current delivered to the 7/ -volt mounted. This is the ideal position for the loud- speaker choke coil in the power tubes; R1 is for the rectifier circuit and this unit, as it keeps the high -voltage leads unit; as in many receivers this piece of R2 is for the power- amplifier tube. from the power transformer as short and apparatus is mounted on the baseboard of Between the rheostat knobs and the right direct as possible. the set. Also, in some sets, an output edge of the panel, three knobs are mounted, The two filter-choke coils (Ll and L2) and the loud -speaker choke coil (LA) are of identical construction, and these are mounted about one inch apart, at the rear R1 edge of the baseboard, starting slightly to r the left of the rectifier tube socket. L4 is Li L2 R8 on the left, L2 is in the center and LI is Ti on the right; as this arrangement makes the simplest possible wiring. The three con- densers of the filter circuit are also identi- cal. These are arranged so that their termi- nals face the right of the baseboard, and are mounted, one behind the in Cl other, directly front of choke coils L2 and L4. The wir- ing is simplest when the condenser near the rear of the baseboard is made Cl, the R2 R3 R4 condenser in the middle C2 and the con- W\M R5 ro. M,1r-Jv 1M--tibV vs, denser nearest the panel C3. R6 Battery clips are used in place of bind- ing posts and these are fastened directly to the wooden baseboard with wood screws. Nine clips are required and they are mounted approximately one inch apart on the left edge of the baseboard. The choke TO 110 V. coil z L3 for the first -detector supply wire is A.C. z mounted near the front edge of the base- a IJ W board, between the condenser C3 and the 3 N m m battery clips. The resistor (Ri) of the O O O O O resistance bank is a long thin unit and it POWER C- C- C+B- 45V.+ 45V+ 90V+ 350V.+ 1 is FILAMENT 25 V. 4'/¿V. A- sr DET 2"-0 ()ET mounted on the base so that it runs from rear to front. Its position is between the battery clips and the choke coil (L4), Fig L Schematic wiring diagram of thei Reich power pack. It will be noticed that a color - starting at the rear edge. The resistor R6 code wiring system is called for; that employed here corresponds to that used in the wiring of the Neutroheterodyne" receiver, for which this power unit was especially designed. is a comparatively short unit and is

www.americanradiohistory.com Radio News tor July, 1928 43 mounted between R7 and Cl, parallel to of this winding connects with one terminal ceiver, and all tubes of both the receiver and near the front end of R7. The re- of LI. One terminal of the high -voltage and power unit must be in their sockets maining piece of apparatus, the fixed re- secondary winding is connected to the "P" when the power is turned on for the first sistor 118, is mounted in a convenient posi- terminal of the rectifier tube socket and time. This is important; for, if the power tion between the transformer and the con- the other terminal to the "C -25" terminal were connected and the tubes were not in denser bank. clip. their sockets, the high voltages developed Fig. C shows the appearance of the The next step is to connect the free ter- would be apt to burn out the filter con- power unit when viewed from the rear. The minal of I.1 with one terminal of L2, and, densers. rectifier tube is in the socket and all parts then, connect the remaining terminal of L2 As soon as possible, after the power has are mounted and wired correctly. As the with one terminal of IA. The free ter- been turned on, the various knobs should baseboard is wood all parts are fastened minal of LA may now be connected with be adjusted to their correct positions. It in place with wood screws. The arrange- the clip marked "B +350". Next the filter is particularly important that the resistor ment which is shown makes for the short- condensers should be connected. First con- R3 be adjusted; for, if the power tube re- est possible wiring and, therefore, is the nect one terminal of each of the three con- ceives insufficient bias, it is apt to over- most satisfactory, but if a baseboard of densers to a wire connecting with the "C- heat. Before turning on the power it is different shape is employed the a wise idea to introduce into the location of the various pieces of circuit as much resistance as apparatus may be shifted with- possible with resistors Rl, 112 out materially affecting the and 113, and then, after the results. power has been applied, slowly However, if the arrangement reduce the resistance u n t i l is changed it is important to proper operating conditions are separate each of the choke coils established. If this system is by at least one inch front all followed the apparatus is pro- surrounding a p p a r a t u s. The tected front damage which might position of the choke coil in the be caused by the high voltage. plate- supply wire of the first In adjusting the various con- detector is also important, and trols, meters should be used if An A.C. volt- this should be placed as far as Fig..4. Front panel and arrangement of controls. Slip, switch; 121 and R2. they are available. possible from the power trans- rheostats; R3 and R4. biasing resistors; 125, detector-voltage (plate) resistor. meter with a range of 0 to 10 former and filter choke coils. volts may be used for checking Also, this instrument should not be screwed 25" clip, and then connect the free terminal the filament potentials applied to the permanently to the baseboard until after of Cl with that terminal of LI which con- rectifier and power tubes, and a high -re- the power unit has been placed in opera- nects with the center tap of the filament sistance (1,000 ohms per volt) D.C. volt - lion; as it should be turned until it is in winding; connect the free terminal of C2 meter with a range of 0 to 150 volts may be such a position that it causes no hum. with the wire joining choke coils LI and used for adjusting the "C -25," "C- 41/2," L2, and connect the free terminal of C3 "B +45" and "B +90." The final adjust- WIRING with the wire joining choke coils L2 and ment of the "C-25" voltage is not made After the assembly of apparatus on the L4. until after the receiver is operating baseboard and front panel of the power The voltage -dividing resistor bank may properly, and then an 0 to 50 D.C. mil- unit has been completed the wiring may now be wired. The first step is to connect liammeter is used for the purpose. This be started. Fig. 1 shows the circuit in the resistors R3. 114, I(5, R6 and R7 in meter is connected in series with the 350 - schematic forms, and in Fig. 2 the complete series, in the order mentioned. 'l'he free volt supply wire and a loud signal is tuned wiring is given in pictorial form. It will terminal of 117 is then connected with the in on the receiver. When the volume of be noticed that the system used in wiring wire ,joining the choke coils L2 and L4. music from the loud speaker is at maximum, the set is very simple and that all wires The center -tap of resistor R6 is next con- the knob R3 should be adjusted until the are located above the baseboard. For this nected with the clip marked "B +90." Two needle of the milliammeter is practically purpose well-insulated flexible wire must wires are then connected to the slider ter - stationary. Of course, the knobs may be be used. minal of resistor R5 and one of these wires adjusted quite satisfactorily without the From the circuit diagram it will be seen is connected to the clip marked "B +45- use of meters; and, if the experimenter is that the primary winding of the power 2nd Det" and the other is connected to one careful, the results will be practically as transformer is the only part of the circuit terminal of the choke coil L3. The other satisfactory. which is connected to the 110-volt, (ì0-cycle terminal of the choke coil is connected to In operating the receiver without the aid house- supply wires. There is in the pri- the clip narked "B +45 1st Det." 'l'he of measuring instruments, the various knobs mary circuit of this transformer a three - slider of resistor R4 is connected to the should be set for the lowest voltages which point snap switch which makes it possible clip marked "C-4 %" and, to complete the give good performance. to turn off the unit, or to change the num- wiring of the resistor bank, a terminal of PROBLEMS OP HUM ber of turns used in the winding, for the resistor 113 is connected to the clip marked purpose of regulating the power. In the "C -25." Lu the case of resistor R3, only After the receiver and power unit is transformer selected for this power unit two of the three terminals are used. and it operating properly, there is an adjustment this switch is built into the transformer is important to make sure one of the ter- which may be made to reduce the A.C. hunt. and requires no additional connections; but. minals to which contact is made is the slider. It has been previously mentioned that the if another transformer is substituted when The construction of the power unit is "stray" field from the power transformer building the set, it may be necessary to now practically complete and, after the re- and filter -choke coils is sufficiently strong connect a switch of this type externally to sistor R8 has been connected, the wiring to produce a very noticeable hum if the the transformer. In the case of the trans- may be considered finished. One terminal first -detector "B +" choke is not properly former under discussion, the three points of this resistor is connected to the wire placed. Whether or not a hum is produced of the snap- switch adjust the power unit joining the choke coils L2 and I.4, and its by this cause may be most accurately de- for operation in 60 -cycle circuits of 110, other terminal connects with the wire join- termined by short -circuiting the choke and 118 and 125 volts, respectively. ing the clip marked "C-25." observing whether there is any reduction There are three secondary windings on of the hum. If the hunt is reduced by this the power transformer; two center -tapped TESTING operation, the choke coil should be revolved filament windings and one 525 -volt plate After completing the construction of the until the hum is at a minimum, and then winding with a capacity of 60 milliamperes. power unit the wiring should be carefully the choke should be fastened securely in One of the filament- heating secondary wind- checked and tested. It should be remem- this position. ings is connected to the filament of the tiered that the transformer T1 develops a There are two other ways in which the power tube, with the rheostat R2 in series potential of 525 volts. and that this is dan- hum may be reduced. The first is to con- with one of the connecting wires. The gerous if not properly insulated. There- nect the case or core, as the case may be, center tap of this winding is connected to fore. it is highly important to make sure of the power transformer, filter choke coils the "B -" binding post of the power unit. that every connection is correct and secure, and filter condensers to the "B-A-C+" The second filament winding is connected and that all wires are insulated thoroughly. terminal clip and then make sure that the to the filament of the rectifier tube with the In order to test the power unit it is neces- "B -" wire of the set is grounded. The rheostat R1 in series. and the center tap sary to connect it correctly with the re- (Continued on page 64)

www.americanradiohistory.com 44 Radio %-eze's for July, 1928 Improving Reception on A Thin Pocketbook

Some Practical Data on Bringing the Atwater Kent Model 20 Receiver Up to Date, at Little Expense and Effort

By Luther C. Dilatush

T'S certainly a big thrill to play around tion than mush and static from the other not all I had hoped it to be, and volume with a superplexodyne, screen -grid side of the continent. The audio is a two - was less. Let this sink in for the last time; tubes, or what have you; but while the stage transformer -coupled affair. Distor- a 171 gives less amplification than a 201A, experimenter is doing this, I think there tion in one of these receivers is not unbear- hut is capable of handling more volume. is another fellow that deserves a little at- able and the musical range will not be quite This point has certainly been made plain tention. He is the man with a three -dial, so limited as some of the manufacturers of enough, but I still hear people say that their five -tube set and horn speaker. If you think new transformers picture it. volume is poor and they want a power tube he no longer exists, just look around. Notwithstanding this, the set lacks the to give them power and more volume. if About three years ago, literally millions ability to produce full, round tones, and the your lack of volume is due to the last tube's of these typical live -tube sets, such as that overloading, line. A power tube will fix shown in Fig. A, were sold. As few of you up. Otherwise, : no. them wear out, someone is using them now. Getting back to the subject, it is now Most of these still have the old horn obvious that more amplification is desirable. speaker; as they were designed to operate Conclusion- another stage of audio. After a horn and do not give results entirely satis- trying resistance -, transformer -, and im- factory with any other type of speaker. It i pedance- coupling, I have hooked up a re- is to the owner of this type of set that this sisto- coupler to my last tube. It really has article is dedicated. high amplification power in the last stage, No doubt this fellow is still using this and it affords real quality in its tones (if comparatively old -fashioned type of set be- the signal going to it is pure). In the third cause he can't afford a new one (I'm in that place, it is cheap, and we are considering dass) and because he doesn't know any in- cost. expensive way of improving it. If you have The reader may now ask about the trans- one of the sets described, would like to im- Fig. A: This type of receiver is one of the formers in the set. Do they not so limit prove your reception greatly have most widely-used in the United States, although -and it is no longer being manufactered. the musical range that decent reproduction from fifteen to twenty dollars-read on! cannot be obtained? In the type of receiver The purpose of this article is not to advance pictured, practically they do not. After a single new theory, but to increase the volume is inadequate for real enjoyment trying new transformers in the set, putting masses. radio enjoyment of the with a cone. A cone? Yes. I believe the resistances across secondaries, etc., I de- . cone that I am using is as good a repro- cided to let the audio end of the set alone. AMPLIFICATION LIMITED ducer as can be had, figuring on a basis of There are two more strong reasons for quality per dollar. 'l'he horn on this ordi- this; undoubtedly new transformers improve First, what have we in the typical five - nary set is the big robber of quality; but the tone somewhat, but we are figuring on a tube, tuned -radio frequency -set, such as the the mere addition of a cone is not enough, value- per -dollar basis, and that lets ex- writer's Model 20 Atwater Kent, shown in for the reasons stated. We want full, round pensive, heavy-core transformers out. Sec- Fig. A? The radio frequency is fairly sat- tones and volume. ond, the average broadcast listener has no isfactory to the average home listener,- who Ali, a power tube? I tried putting one desire to take a factory -made receiver apart would rather hear music from a nearby sta- in the last socket of my set, but quality was and rebuild it.

P G G P G G P TO SET {¡ TO O SET O SPEAKER 1 MEGONM RESISTOR_ .1 MEGOHM O )'B+4MEGOHJ, COUPLER : MEMO/

g+ F RESISTOR/ COUPLER FIG. i O O J C- A-C+ A+ B+ O B+

TO SET _P G G P TO A- SET

TO A- B0 . Z WAY SWITCH SPEAKER gyp` RESISTOR 1 IIEGOHM a I COUPLER 110 VOLT A.C. q MEGOHM) o

B+ F FIG.3 TO'b POWER UNIT IF USED FIG.2 O o A- C+ B+

Three different methods of adding the additional stage of resist- 1 and 2 the extra tube works of the storage "A" battery; in once- capacity -coupled amplification to the old receiver. In Figs. Fig. 3 on A.C. supplied through a step -down transformer.

www.americanradiohistory.com Radio News for July, 1928 45

FEW PARTS NEEDED vised from the standpoint of economy. This the binding posts in the back, remove the tube draws very little current from your eight screws that hold the panel, and slide Considering all these facts and limitations, house circuit; but it would be necessary to the panel out. Take a piece of flexible wire, the final result was an added stage of re- charge the battery somewhat oftener if the of ample length to reach to your new tube, sistance-coupled audio and a home -made power tube operated from that source of and tin one end for soldering. Now lay the cone speaker. As we are considering low current. Unless you wish to be able to panel on a table, dials down, and stand cost as a primary essential, let's sum up change quickly from five to six tubes, omit facing the wiring under the sockets. At the cost now. These figures are slightly jacks; I have them on my set but never the extreme lower left -hand corner you will above what the large city stores charge for use them. If you run this extra tube from see a hole in the sub -panel, with a wire your storage battery, no extra rheostat will coming through it and connecting directly be needed. to the nearest contact of the nearest socket. This is right below the speaker posts. LISTS OF PARTS Solder the flexible wire to this contact Here's the shopping list for the amplifier: spring, where the wire coining through the one 171 -type power tube and socket for the sub -panel is soldered. This is your "A -" same; one .01 -mf. fixed condenser and two wire to the power tube. It will now be grid-leak mountings; two resistors, one necessary to advance the right -hand rheo- 1110 -, one 1 /4- megohm. stat a little further to bring the tubes up A double -circuit jack and an open -circuit to proper brilliancy, as another tube is now filament- control jack are optional, as ob- connected to this rheostat. served above. Now, a word about "B" and "C" cur- For A.C. operation, add one 6- or 8 -volt rent. If you are using "B" batteries, put bell- ringing transformer, one 200- or 400 - three heavy -duty 45 -volt batteries, or 135 ohm potentiometer, and one 20 -ohm rheo- volts on all amplifier tubes. Give the de- stat. tector tube all it will take without howling. The hook -ups with and without jacks are For the sake of reducing the drain on the Figs. 1 and 2, respectively; while Fig. 3 "Bs," use about 30 volts of "C" current on gives the connections when A.C. instead of the power tube. This voltage can be built storage -battery operation is adopted. up with ten -cent three -volt flashlight bat- You will notice a two-way switch in the teries. This will cost a dollar for thirty circuit of 11g. 3; this is very convenient, volts and, by experience, these batteries and is much cheaper than any relay ar- last well over a year, as there is no current rangement. Fig. C illustrates a switch of drain on them. The only requirement is to this type installed in the end of the radio keep them reasonably dry. table. Of course this may be replaced by If you have a "B" power unit, however, a knife- or snap- switch in back of the set. and the current drain need not be so seri- The use of this eliminates the use of the set ously considered, I don't see where this switch; just leave the latter on all the high "C" voltage is an improvement. In time. 'l'he wire marked "to set" goes to the theory you should have it, but 15 volts Pig. C: How the twoway switch shown in outside speaker post, next to the end of the works as well as 30 in mine. In a set that Fig. 3 is mounted on the side of Mc cabinet cabinet. I recently improved according to these in- holding the radio receiver. only 0 volts is used and the set BATTERY OPERATION structions, works like a charm. Use your own judg- these parts; and, no doubt, you have some If you want to run this tube on your ment. Of course, put the full voltage of the of them lying around somewhere. storage battery, first take all the wires off unit, up to 200, on the power tube.

171 -type power tube $3.50 Socket .40 Coupling condenser and two resistors 2.50 Cone unit (about) 7.00 Cone paper .75 Cone apex .25

Total $14.40 You will probably have to buy a 25- cent can of cone -paper cement and some ribbon and braid to decorate the cone, if you care for appearances. A.C. equipment, consisting of a bell- ringing transformer, potentiometer, and rheostat, is optional. Remember, this cost of about fifteen dol- lars includes the power tube and speaker. Compare this with the cost of an adver- tised speaker alone! Now let's stop raving for awhile and get down to actual work. The best place to start is with the amplifier. 'l'he first ques- tion might well be, where to put it; Fig. B shows where I put mine. This arrangement is recommended as convenient and out of the way when the set is placed on a battery table or cabinet. However, a small board or box arrangement behind the set will not be unsightly, and will certainly work as well. The twisted wires going clown from the power tube are the A.C. leads, while the "B" and "C" connections are cabled. The filament is lighted by alternating cur- rent. The potentiometer may be seen at the right of the "C" battery, and the bell - Fig. B: The tube and the other parts comprising the extra stage of amplification are fast - ringing transformer is on the other side of ened in the upper left corner of the battery compartment. The white object on the right the storage battery. A.C. operation is ad- wall of the cabinet is the two -way switch.

www.americanradiohistory.com 46 Radio News for July, 1928

CÓN$TRUCTINO THE CONE trouble with the apex of the cone. Take job, do not omit this reinforcement. The out tiny V- shaped pieces until the paper apex now be Next in line is the cone. Get a sheet of adapter should attached. does not wrinkle and cut a small hole at the coík °.diaphragm paper, a small can of Next is the decoration. Fig. E shows exact apex for the adapter to fit through. how mine is done. cement for the same, and an apex. Don't This is just a suggestion. You are now ready to cement the joint on The four cone economize on a $2.95 unit; get a good cone strips that panel the into the cone. Give the two sicles of the joint a four unit with a rather heavy magnet. equal parts are half-inch brown rib- light coat of the cement and let it dry. Now bon First, let's do the cone properly. Take glued to the surface. The main reason give it another light coat and press the two of the familiar pin, string, and pencil arrange- for these strips is the fact that one sides firmly together. Do not use too much 'l'he ment and mark out a 30 -inch circle; care- them covers the joint in the paper. cement or it will run out on the front sur- braid at the edge is sewed on; this makes fully cut this out, and cut out a sector 6 face the cone. An electric iron, slightly a workmanlike inches wide. When finished, the cone will of more job than trying to glue warm, can be used advantageously for iron- the braid to the edge. One -half of the be approximately 28 inches in diameter. ing out this joint. Do not use too much is on the and one-half on the This was found a happy medium between braid front heat, or it will curl the joint and scorch back. The do show, even on the very large and smaller cones. It does stitches not the paper. Now cut a six -inch circle out not have the familiar nasal twang of some rather close inspection. Of course, decorat- of the remainder of the cone paper, and fit it ing is optional, and may be done to suit the of the smaller cones, and it is much easier to smoothly inside the cone at the apex. There taste of the individual. Next is the mount- handle -and to find a suitable location for - does not have to be any lap in this. Give ing of the unit. than the larger cones. the entire underside of this reinforcement Now bring the cone around into shape, MOUNTING THE CONE with a half -inch lap for glueing. Do not a good coat of cement and be sure that, make the lap any larger than this, or it when it dries, there are no loose edges to Fig. D shows how the unit is mounted on the wall. First, the cone on the floor, will curl and spoil the regular surface of rattle. (This advice applies also to the lay and push a piece of wire down through the the cone. No doubt you are now having cone proper.) If you want a smooth, strong apex until it just touches the floor. Meas- ure the length of this wire and add about % -inch for the stylus to extend through the cone. For example, let's assume that the result is 8% inches. Now subtract the dis- tance from the base of the cone unit to the end of the stylus. Say this is 3% inches; that leave 4% inches, by which the unit must be separated from the wall. A spacer is built up of blocks bradded together, as shown, and the unit is mounted upon it. Two screw -eyes are put in the top of the block about an inch from the front; now attach the cord as illustrated. Make each side of this about nine or ten inches. Be sure that the nail holding the unit will not touch the cone! Hold the unit on the wall so that the stylus cones where you want the cone to center. Now draw up the cord and drive a small nail into the wall to hold the unit in place. Be sure that the -block Fig. D: How the cone's driving unit hangs Fig. E: The completed cone hanging in place on the wall. over a bookcase. (Continued on page 62)

Radio News Monthly Prize for Constructors - --An Announcement

E regret to disappoint our readers, as well as those to each such experimenter who presents a receiver, power who have submitted entries, by our inability to an- pack, or other radio apparatus which embodies something nounce and publish with full constructional details a actually new, and is suitable for a Blueprint Article which will Prize- winning Blueprint Set this month. The fact is that, out present a possibility for any considerable number of our read- of the several entries which have been received to date, none ers to work on. In addition, it will defray the expenses of the fills the bill satisfactorily. inventor in taking out a patent in his own name, on his device, 'ro win the hundred dollars, an entry must be novel and if it presents a patentable feature. practical enough so that we are justified in publishing it. A We repeat our conditions: a clear, clean schematic diagram skillful and workmanlike construction of an old circuit will in ink, and one or more good sharp photographs, proving actual not do; neither will a new idea which depends upon mechani- construction, must be sent with each entry in this contest, as cal construction so difficult that the majority of our readers well as a statement of what has been accomplished. The manu- cannot undertake it. The accomplishments of such construc- script must be in typewriting or written in ink in legible hand- tors are creditable, but not suitable for the purpose announced writing; each sheet and illustration must bear the constructor's -the promotion of new constructional work by our readers. name and address, and all must he fastened together and We cannot undertake to accept and develop ideas on which mailed flat. the entrant has done no practical work. It is not the idea, but If an entry shows sufficient novelty, merit and practicality the putting of it in execution, that makes a man an inventor. to be considered further, the constructor will be informed of In addition to this, most purely theoretical ideas are imprac- the fact, and instructed whether or not he should ship in his ticable, as those who submit them would soon find. apparatus to this office, and what further information is re- We cannot accept for this purpose a new device, however quired from him. well done, which is designed by a manufacturer or an engi- RADIO NEWS RESERVES THE RIGHT TO SUBSTI- neer working for or with him; this would be unfair to the home TUTE AND SPECIFY OTHER APPARATUS IN THE and shop constructors and experimenters, to whom this offer PUBLISHED ARTICLE; ALW AYS PRESERVING 'l'HE is addressed. MAIN FEATURES, HOWEVER, OF THE ORIGINAL RADIO NEWS, however, stands ready and willing to pay $100 DESIGN. \\ \\ \\ \

www.americanradiohistory.com Radio News for July, 1928 47

much more complicated in mechanical con- illustrated in the accompanying picture. A A Banjo Speaker struction. bridle of heavy wire is inserted in place FEW novelties will afford more amuse- In building a cage aerial, one of the most between the rings of the aerial and lead -in, ment in the radio field than the banjo and this is securely soldered to each ring. speaker. It can be made in a few mo- The bridle is slightly shorter than the nor- ments; or, if a permanent arrangement is mal distance between the rings, thus allow- desired, this may be made also by the ing a slight slack in the lead -in strands. expenditure of a little more time. With this method, the entire strain is taken The requisites are: a banjo, tenor -banjo, up by the bridle, and there is no tendency banjo -mandolin or other instrument of the for the lead -in strands to break. -L. B. banjo family. (Banjo -ekes are too small Robbins. to give really satisfactory results.) If the instrument is fitted with a resonator, so much the better; as this conceals the unit. A small cone-type loud- speaker unit is An Automatic Control also necessary, with a cord connector, a ADEVICE which may be made to com- connecting cord and a standard radio plug. A cagetype lead-in may be strengthened pensate for the change The unit (U) is placed inside the banjo, mechanically with a bridle of heavy wire, as automatically illustrated here. in efficiency of a radio receiver on different as shown in the first illustration, and a small C-clamp (C). wavelengths is illustrated in the picture on clamped there with difficult problems is attaching the lead -in wire; and this is true particularly if the

compliance with a popular de- 1 ¡nand, "Radio Wrinkles" will again appear as a featured department of RADIO NEWS, beginning with this is- sue. In. the March issue the final prize award for "Radio Wrinkles" was published, and the department was discontinued. However, during the past few months so many letters hare been received requesting snore "Wrinkles" that it has been decided to re- establish the department. A year's subscription to RADIO NEWS will be given in compensation for each accepted item. If the author .4 banjo is converted into a loud speaker b clamping the speaker unit (G') in place with a of the wrinkle is already a subscriber, C" clamp (C) as shown above. his subscription will be extended one .4 rheostat resistance unit, mounted on the year or he may accept a one year's shaft of a tuning condenser as shown, makes subscription to Science and Invention possible many circuit improvements. This arrangement will not injure the in- or Amazing Stories, both published strument in the least; but, as the contact 1 1 the Experimenter Publishing Co. this page. It is a standard variable con- by alone, with the head is made pressure denser, to which has been added a vari- the speaker may blast at times. If a per- able resistor. 'l'he unit is so designed that is unit is manent installation preferred, the (Continued on page 83) clamped directly to the bar with the usual lead -in is also of the cage type. The lead -in clamp used in mounting units. :\ hole is of the writer's aerial was of the cage type pierced in the head of the instrument, at the them. However, this center, and the usual apex, cut clown to method proved un- I/-,-inch diameter, or less, is attached. satisfactory; as fre- In use, the cord is connected to the unit quently, during heavy and plugged into the receiver in the usual gales, one or more manner. It can be used, of course, for the of these attachments reception of any broadcast; but, if a banjo would break off. solo can be tuned in on the phones and the After considerable speaker then connected by means of an experimenting an ex- extension cord in some other room, a- great cellent method was deal more amusement can he secured.- found for connecting H. C. McKay. a cage lead -in with a cage aerial and this is

Considerable amusement A "Cage" Connection may be secured by hav- ing someone hold this MANY dyed-in -the -wool radio fans pre- speaker while it is re- producing a banjo solo. fer to use cage aerials instead of the Of course, the guests usual single- strand type. The cage pos- should not be let into the secret till afterwards. See sesses certain electrical advantages, hut it is first article on this page.

www.americanradiohistory.com Kadio News for July, 1928 Simple Rentoitte CorjtrcI Device byffluiiuinf Cr,s4

THE prime requisite of a radio re- and that is, that the wires in the cable shall heavier cable (No. 14 or No. 12), taking mote- control device is that it be com- be sufficiently heavy to carry the "A" cir- off the leads to the various remote controls pact. It should be also cheap and tuit current without appreciable loss in as they are wanted in the different rooms. easy to make and capable of being voltage. The heavy wire (about No. 18) It is highly essential to use wire which has adapted to almost any form of circuit. In which is used in the average battery cable insulation of different colors, in order that working along these lines, the writer has has been found satisfactory so long as the the connections may be readily identified; reached what he believes to be a practical distance does not exceed twenty-five or but, where this cannot be done, a "tracer" solution of the problem. thirty feet. For distances in excess of this, circuit, consisting of a low- voltage battery The instrument described in this article the size of the wire should be increased and a pair of head receivers, should be used will not tune the set and was not designed to do so, for several very good reasons. In the first place, the average set-owner's re- ceiver is left tuned to one station most of LAST TUBE IN SET. BOX \r the time, anyway; and constant adjustment i o--p0 of its dials is not necessary. In the second OUTPUT place, after experimenting with such de- JACK vices for several months, the writer has MW been forced to the conclusion that their expense, size, and the fact that they can- 50,000 -OHM VAR. RESISTOR not be used on every type of receiver, necessitated the abandonment of the idea LAMP) of using remote tuning devices, in the ordi- nary borne, in favor of the little instrument C v about to be described. This device is so simple and cheap that o anyone can build one in an evening. Where SW. SW. the necessity arises, two, three, four or five RHEOSTAT" of them may be connected in parallel, in such a way that the radio set may be turned S -W!RE CABLE --"F i _, on or off from any room in the house. The c,. variable high resistor employed makes it possible to control the volume from a whis- Schematic arrangement of the simple remote- control unit described here. per to the full power of the set. One or all of these controls may be used at the saine somewhat, because the resistance of the to determine the ends of the various wires. time, to control different speakers in differ- regular wire may be too great. Where If the ends of the wires are grounded, one ent parts of the house. several of these remote controls are used, at a time, while the other ends are tested There is just one essential requirement, it is advisable to wire the house with with the receiver and battery connected to

A.C. T+ BES CONTROL BOX Pi

OUTPUT OF SET jmolACK JACK 2-WIRE (ABLE SEPARATE S0.000- OHM v FROM 110V. CABLE LAMP VAR. RESISTOR SW 1.1 RELAY\ i 4WIRE CABLE LAMP FILAMENT SÓ.000, OHM 00V) TRANSFORMER VAR. RESISTOR

III m / WIRE CABLE FOR 110 .VOLTS

SWITCH LOCAL BATTERY 110VOLT A.C. FIG.4 FIG. 5

At the left, the remote- control unit is used to operate an relay. With the direct A.C. connection at time right, a power electric set by means of a local battery and high- resistance switch and a 110 -volt pilot lamp must be used.

www.americanradiohistory.com Radio News for July, 1928 49

an adjacent ground, it will be a simple mat- the "A" battery circuit, the polarity having the other terminal of the resistor is wired ter to tell the wires apart. Each should be no effect in this case; while the remaining to one of the phone tip jacks. 'l'he other tagged, if the insulation is all of one color. terminal on the socket will be connected to jack terminal will be wired directly back, the opposite battery terminal. 'These two through the cable, to the remaining output DESIGN OF THE UNIT battery connections may be made either at terminal on the set. The remote -control unit itself is only the set, direct to the battery or through a about six inches long and two inches wide, cable which may be run throughout the VARIOUS CONNECTIONS and set into a box about two inches deep. entire house. The variable resistor is sim- This is shown in Fig. 1, which, in addi- The panel may be bakelite, hard rubber or ply connected to one of the output binding tion, shows the actual terminals as they arc a suitable piece of wood, secured in a posts or the output jack on the set; while connected to the set. Note that one wire (the lowest one) runs inside the set to a point above the battery switch. if no bat- tery switch is used, this connection will be r made above the first rheostat. With this connection, the switches on both the set and OUTPUT the remote control are interlocking in such O a way that, when either switch is turned on, the red light in the remote control will be turned on. In Fig. 2, we have the same arrangement, but in this case it is necessary to turn on a "B" socket -power unit when the set is / turned on, and a trickle charger for the ! storage `A" battery. when the set is turned SW off. A low- resistance, double- acting relay does the trick here and it should be con- RHEOS.fr L nected exactly as shown in the drawing. These devices may be purchased at almost o CONTROL 8 +} ON SET / any radio store. You will note that the UNIT oo g+ BOA relay is so connected that, when the "A" RELAY(LÓW battery circuit is closed, the armature will come down and make contact, closing the RESISTANCE) "a" ON BATTERY 110-volt circuit and thus putting the "B" 110V FIG. 2 supply unit in action. When the "A" hat - TRICKLE CHARGER ac. tery circuit is opened, the armature on the relay springs upward and closes the 110 - volt circuit to bring the trickle charger into use. It is highly essential that this relay be o- of low resistance; otherwise it will take so much current to pull it down that the "A" battery will not be able to supply enough for the tube filaments. (An old telegraph sounder will NOT do the work.) Fig. 3 is simply a repetition of Fig. 1 ex- 01'0 VAR . RES: cept that it shows how two remote controls may be used at the same time. Additional instruments may be added by simply con- FIG.2-A necting them in parallel. FOR ELECTRIC SETS Above, the remote- control device wired for use with a "B" unit and trickle charger; at Fig. 4 indicates the remote control as the bottom, the connections wizen an output filter is added. The "A" battery is con- connected to a set using full A.C. operation. nected across the terminals marked "A." (Continued on page 64)

wooden or metal box in such a way that the entire assembly will look like a miniature radio set. It is suggested, though, that the panel be placed on top instead of the side, LOUD SPEAKER PHONES as this will make it somewhat easier to ON SET. 50.000 operate. LAST TUBE 5-WIRE CABLE OHMS Exactly in the center of the panel we IN SET. place a variable high resistor, in the :-t neighborhood of 50,000 ohms as its maximum o w.wo, value. On one side of this we place a pair of (LAMP tip jacks, or, as in the case of the unit shown J in the illustrations, a combination jack. On

the other side and spaced at equal distances SW from the center, we have an ordinary bat- tery switch, of either the push -pull or the ó CONTROL BOX) toggle type. Above this will come a minia- ` "'- IN BEDROOM ture -lamp socket, fitted with a small six - SWITCH \ 5-WIRE volt bulb. 'Through the panel over this IN SET CABLE- bulb is inserted a ruby lens, which will SET IN DINING ROOM show a red light when the battery switch is LAMP- --; turned on; this is optional, but its use will -I SWITCH-- be found both attractive and advantageous. ,-JACK ALOUD SPEAKER OHM VAR. ^1 The wiring is clearly shown in Fig. 1 and 50,000 - Also in the drawing of the back of the CONTROL BOX IN LIVING ROOM. FIG. 3 panel, Fig. 6. One side of the lamp socket is connected to one of the terminals on the battery switch, and from here a wire in the It is possible to operate several speakers from a number of these remote- control units cable is taken to the set. The other post on when wired as shown. The pilot light indicates at every unit if the set has been turned the battery switch will go to one side of on at any one of them.

www.americanradiohistory.com 50 Radio News for July, 1928 Interstage Coupling for Screen -Grid Tubes

Successful Experiments with A Superhet Using Two 222 -Type Tubes for the Stages of Intermediate -Frequency Amplification

By E. H. Rietzke and N. M. Cooke

MANY articles have been written fication he wishes to use and the manner on the theory and operation of in which he is to obtain the desired se- the screen -grid tube; several cir- lectivity. cuits employing this tube are now DESIGN OF THE CIRCUIT on the market. Many of these circuits are plainly designed to take advantage only of The question of how many stages of am- the extremely low internal plate-to -grid plification are desirable is simply a question capacity of this tube, thus avoiding unde- of how efficient each stage is made. With sirable feed back, but with little attempt to the circuit design given later in this article, obtain the high amplification possible with two stages give as much amplification as a properly -designed circuit. it is found practical to use with a short The writers have done considerable ex- aerial. The amplification obtained with perimental work for the purpose of deter- three stages brought the noise level too mining the most practical circuit to use for high for good broadcast reproduction. best results with this tube, particularly in The desired selectivity may be obtained The coils shown here are of solid mire, and the broadcast band. By good results we in several ways. The band -pass filter with therefore slightly smaller than the equivalent mean good reproduction, high amplification high impedance, and broadly -tuned inter- "Litz" coils described. The transformer peaks per stage, and sufficient selectivity. stage circuits, afford probably the ideal at 137 kc. method of obtaining selectivity with a good Dr. Hull, the designer of the American quality of reproduction. Another circuit in his article, in screen -grid tithe, shows will give good selectivity and good the that the Physical Review, that he obtained with the screen -grid tube is most stable amplification highest amplification and the high -impedance, broadly -tuned plate cir- frequencies. a circuit at comparatively low cuit for the screen -grid tube, with a sharply- Experimental work with practical circuits ahead of the first writers. This tuned input transformer has confirmed this for the intermediate amplifier. The third method the ease with which selectivity and fact, and is the use of a fairly- sharply -tuned circuit of may be obtained, are simplicity tuning in each stage of intermediate- frequency in favor of the super- convincing arguments amplification. Another de- heterodyne type of receiver. With proper design, all of the above termining factor in favor of the super- although very methods will give excellent results; heterodyne is the fact that a -high- two are better than the constructed to the first somewhat impedance circuit can be third circuit for broadcast reception. This give uniform amplification over the entire is because several sharply -tuned circuits, broadcast band, or in fact over any desired while giving high amplification, make the -band. The low intermediate fre- frequency circuit too selective for good reproduction. quency also makes the matching of the Some experimenters, however, prefer this circuits a comparatively simple matter. type of circuit; so specifications will be After determining the type of circuit to given in this article for interstage coupling use the experimenter must decide the fol- devices to be used with such a circuit. lowing poin ts : how selective he wishes the The coupling device above, substituted for LI in Fig. 1, eliminates the need for an input roreiver to he: how many stages of ampli- filter. LOW -LOSS CHARACTERISTICS Interstage coupling circuits may be roughly divided into two classes, broadly- peaked and sharply- peaked. Both, when used with the screen -grid tube, must have a very highly resonant impedance; this is obtained by keeping the losses very low. Since this is an absolute necessity if high amplification is to be obtained, the follow- ing circuits may all be assumed to be of the low -loss type. Broad or sharp tuning in a parallel cir- cuit depends upon the inductance-to-ca - pacity ratio of the circuit. To make a cir- cuit tune very broadly, the inductance-to- capacity ratio must be high. Conversely, to obtain very sharp tuning the inductance roust be small and the capacity large. For the interstage coupling circuit be- tween the screen -grid tubes, where a large inductance -to- capacity ratio is desired, there should be employed a helically -wound choke, which has an extremely small distributed capacity and a large value of inductance and at the same time a very low value of resistance; such as the Samson No. 85. Thus this circuit meets the requirements of both high impedance and a broad peak. Fig. 1 shows one stage of coupling be- The coupling between these two I.F. stages includes an 85- millihenry choke, LI, and an .002 -mf. con denser. A suitably -tuned input must precede this I.F, amplifier, which is not selective. tween two screen -grid tubes using such a

www.americanradiohistory.com Rauco News for July, 1928 51

choke (Ll) and a .002-mf. condenser as the The condenser C2 (shown immediately GRID CONTACT interstage coupling device. above RI) should be connected directly OUTER from the screen -grid terminal to the nega- INNER A SHIELDING HINT SCREEN SCREEN tive filament terminal on the socket. Another and similar choke L2, combined If it is not GRID desired to use the resistance GRID- with the .01 -mf. condenser Cl, forms the method of obtaining the correct screen -grid filter in the plate- battery lead. This filter voltage, RI may be replaced by another is placed just inside the shield and the R.F. choke and the plate battery tapped at condenser C1 is connected to the shield. between 30 and 40 volts. (This value does When a common plate battery is used for not agree with the work of some experi- all tubes -the ordinary condition -the filter menters who have been working with the in the plate leads must be used. It is well UX-222 but, with this circuit, a screen to mention here that the best results will be voltage of from 30 to 40 volts gave con- obtained if all connections to the shield siderably better results than the higher are made at the same point. In this way voltage usually used.) the circulating currents in the shield will It cannot be emphasized too strongly be greatly reduced and the effects of the that, with the high amplification obtained shielding will he improved. from this type of circuit the interstage The correct value of grid leak to use shielding must be as nearly perfect as pos- with this circuit is found between three sible. and five megohms, and the coupling capacity The circuit described above is not in the should be about .002 -mf. Neither of these least selective; so a tuned input trans- values is particularly critical, but in ex- former of some sort must be used to obtain perimental work the best results were ob- the desired selectivity. The writers used tained with the values given. an input transformer tuned to 137 kilo- cycles, and obtained excellent results with SCREEN -GRID VOLTAGE the chokes employed. A 50 -kc. input was The 500,000-ohm resistor, R1, is used to tried, but this frequency brought the noise obtain the correct value of positive po- level much too high for good reproduction. es tential upon the screen grid. The ad- The 137 -kc. tuned transformer is described vantage of this method of obtaining the cor- below. rect screen -grid voltage was discovered in The coupling leads between stages must transmitter work. It has been found that, be shielded. Outside the shielding, excel- with this resistor in the circuit and con- lent results can be obtained by using nected to the source of plate voltage, the shielded ignition cable, grounding its shield- voltage on the screen grid will automatic- ing and making the holes in the interstage ally adjust itself for the particular plate shields just large enough to force the voltage used. This is also advantageous, shielded ignition cable through. All radio - as it permits the same high -voltage tap to frequency leads should be made as short The relative positions of the elements in the be used on both the plate and screen -grid as possible within the shields. 222-type screen -grid tube. circuits. (Continued on page S1) Methods of Obtaining Suitable Screen-Grid Voltage By H. A. Pelton

THE theory of the screen -grid tube is Why not, then, make some arrangement voltage will also vary -in nluto.,t direct pro- now fairly well understood and many whereby we can obtain this screen voltage portion. In addition, we no longer require manufacturers and experimenters are en- inside the receiver and, at the same time, the extra screen- voltage lead to our bat- gaged in a race to see what heights of maintain a fixed ratio between screen and teries. amplification can be reached. Various cir- plate voltages? Since the ratio between plate and screen cuits and shielding plans have been evolved, voltages is not extremely critical, it is evi- but one arrangement has remained un- USE OF SERIES RESISTOR dent that the size of the series resistor will changed, i.e., the method of obtaining the Such a system is shown in Fig. 1. Here not be critical and our work is simplified; positive bias on the screen -element. we are using a simple series resistor, It, to since we can use a resistor of the standard The standard method has been to take off reduce the full plate voltage to the value size nearest to the indicated value. a tap, somewhere along the plate battery. required for the screen. Now, if the plate For example: Curves of screen current This plan is very good, so long as the vari- voltage varies for any reason, the screen (Continued on lwye 61) ous batteries maintain constant terminal voltage; but consider what will happen after the set has been in use for some time and one or more of the battery units deteri- orates. A set of screen -current and plate - current curves (plotted with fixed plate voltage and variable screen voltage, or with fixed screen voltage and variable plate volt- age) will serve to show the difficulties which are sure to result if the ratio between the plate and shield voltages is not maintained within certain limits. It is true that this ratio is not extremely critical; but any serv- ice man can assure you that it is not at all unusual to find two identical batteries, connected in series for the same length of time, whose voltages differ as much as ninety per cent. In addition, this method requires an extra lead, which must be brought out of the set through the already- crowded filter system and cable. Figs. 1 and 2 show alternative methods of insuring automatically a proper voltage between screen -grid and plate. The latter is somewhat easier mechanically.

www.americanradiohistory.com 52 Radio News for July, 1928 Letters from Home Radio Set Constructors

stations are 2,500 miles u.r LINEN -SPEAKER DOPE onal panel measures only seven inches across the station to log. Coast the cabinet is only six inches deep. more distant. NEWS: flat sides, and Editor, RADIO The reception is clear as a bell, and the selectivity EDWARD ETTS, a parliamentary expression, may I rise To use made possible by the double tapping arrangement 21 Urquhart St., Rumford, Maine. to a point of order, to explain why collodion is for the purpose of coating is good. (theoretically) unsuited connected to only a light- socket loud speaker? The writer has With this set a linen- diaphragm aerial, and an ordinary ground, I have listened spent a lifetime in the drug business and has made will say that it is a solu- to stations WGN, WSM, WBAP, WPG, WSAI, and used collodion; I such a set cotton in alcohol and ether; the WGY and others. I can recommend tion of nitrated who has been doubtful about a fixed is highly volatile, and when evaporated to anyone solvent crystal hook -up. leaves a coating of cotton on the linen cloth; it The speaker will E. R. THOMPSON, is not moisture -proof nor hard. Kentucky. to the amount of moisture 332 Orchard Street, Owensboro, vary its tone according of the crystal have been thrown is highly inflammable, enough so to (The merits it holds, and so good and hazard. into the shade since tubes became make it a but this example shows the possibilities A varnish should be used. Any automo- ducat; "Deco" which may be realized under the proper conditions. bile shop that does this work can spray the speaker make a better job than with This little set represents more elaborate workman- with a lacquer and crystal, which are not Lacquer, such as used on airplane wings, ship, and a specially- biased a brush. found in the little "Beginner's" crystal set i1lLs- is liquid celluloid; that is, celluloid dissolved in trated on page 33 of this issue; but the latter may acetone with amyl acetate ( "banana oil" so called). the celluloid in be adapted as the skill of the constructor permits. If one cares to prepare it, dissolve reception making it rather too thick to use, and Incidentally, Mr, Thompson reports of the acetone. can hardly be guaran- oil. This gives an almost trans. more than 750 miles, which thin with banana with the best of crystal detectors.- EDITOR.) lucent lacquer. Omitting the banana oil and thinning teed with acetone. makes a white -enamel finish. Celluloid for this purpose may be had from AN INSULATED GROUND image some moving -picture place (old films). The Editor, RADIO NEWS: or photo impression can be removed by soaking While experimenting with buried antennas, I the film in a solution of potassium carbonate, buried three copper plates (insulated with rubber) about 'A ounce to a half pint of water. A few to a depth of three feet, and attached the lead hours in this will allow the film to be removed wire to the ground post of the receiver, with my by scraping with a dull knife. Not removing the 120 -foot three -wire aerial remaining attached to the lacquer. film would make a dull or opaque The layout of Mr. Thompson's crystal set (see Celluloid is nitro- cotton, plus camphor and other :::::::1,;;;;,,,,,;,,,,,,,,,,, I ::uom::,:m:::::::,::,,,,u ,,o::::::::::,t,:,,,,,,,,,t ,:,:::,,,,,,,,::,,: first column) on its six -sided front panel. ingredients that make it hard and impervious to ,,,:,.,,:tt water, and while inflammable, it is not nearly so easily ignited as collodion, and when ignited burns for this page should be as LETTERSshort as possible, for so many are re- WELL, SINCE YOU INSIST - with less violence. ceived that all cannot be printed. Unless Editor. RADIO NEWS: R. P. DANIEL, a set is made from a published descrip- Since I built the I have been watch- Antonio, Strobodyne, South Park Pharmacy, San Texas. tion, a schematic sketch should be sent; ing RADIO NEWS, expecting someone to sing its photos can be used only to illustrate a praises, but. having seen none, I am breaking away novelty, and then only it large and very to speak for BUILDS SHORT-WAVE SETS FOR clear. Inquiries for information not given from the dials this "orphan. (The BOY SCOUTS here should be sent to the constructor "orphan" does not lack for friends. At least three Editor, RADIO NEWS: direct; but he should NOT be asked to thousand of these receivers have been constructed I have been having a lot of real enjoyment furnish data already published, here or in this country alone, and evidently to the general making short -wave sets. elsewhere. satisfaction of their users. We merely feared that It might he interesting to you to know that I This department is for free discussion the subject might seem monotonous if given the have taught a number of Boy Scouts how to build to the extent that space permits; but full sway of this page -EDITOR.) I had some sets and have made them learn the code. Titis RADIO NEWS accepts no responsibility trouble in adjusting this set but, with the kind has made it very easy for the opinions of readers as to the rela- assistance of Mr. Lacault, this difficulty was over- has been play for them and tive merits o: apparatus and circuits. to teach them to signal by "wig- wag." One of the come. It was only a case of too much regeneration; things we are trying to do for the boys is to in- I had the R.F. rheostat and potentiometer adjusted s,,,,,.mrirrirmirri,.,,,,,,,,tt:,:tt: rm. ._,.,,::,::t: t:, crease their powers of observation; and this cer- above the oscillation point. tainly has dour that. It was very easy to find Now let me tell you that the Strobodyne is a boys who wanted to build sets, and to keep them antenna binding post of the receiver. You can great set. When I think, sometimes, that I am interested I would tune in an amateur station who imagine my surprise to find stations rolling in listening to some Brooklyn station, I am "shocked" was sending code. This was a mystery to them with more volume than with the usual ground. And to hear the announcement come from some station until they !earned the code and you can imagine let me say that my ground system consists of five a thousand miles away. This is what the Stro- the rest. different grounds connected together, and includes bodyne will do any night: it will bring on the GEORGE O. HOWARD, buried pipes, zinc tins, galvanized wire, and boiler loud speaker distant stations with 10 kc. separation 1736 So. Xanthus Ave., Tulsa, Okla. tubes driven into a septic tank (always wet). when the locals are on. One night last week I (In two senses, we may say this is constructive However, I can get better selectivity and better got to listening to WJZ at about 9:45 p. m., and work. There is no better hobby for active, intel- volume with tl.e insulated ground. The plates are began to move downward on the dials. The fol- ligent boys Chan short -wave radio; and we may buried on edge, with a short ground lead to set. lowing stations came in, with more volume than commend Mr. Howard's example to Scout execu- JOHN G. BAIN, some locals: tives and all others interested in work for boys R. R. 2, Ladysmith. B. C., Canada. WJR, 441 meters; WLW, 428; WOR, 422; WGN, and young men.- EDIToR.) 416; CKAC, 411; WFI, 405; WTAM, 400; WHN, 394; WBBM, 389; WGY, 379; WSAI, 361; PRAISE OF THE STROBODYNE CKNC, 357; WIP, 349; WLS, 345; WSM, 337. Editor, Remo NEws: When I came to WSM I was attracted by their As I do oat recollect seeing any mention of old -fashioned music and stood by them the rest the Strobodyne in this department of late, I trust of the evening. I pick up the Coast any night, a few lines a:,out mine may be of interest. except on very bad ones. I use an aerial 45 feet The parts used and layout are those specified by long and 18 feet high. RADIO NEWS, except that my last stage of audio As to quality of reproduction, I am satisfied is push -pull. I have had several sets, including to know that some of my friends who are musicians two supers, hat consider the Strobodyne the best will sit and listen to the Strohodyne and count all -around set of the lot. It is sensitive and sharp, practically every instrument in an orchestra. Many loud and clear- qualities that do not always go thanks to RADIO NEWS for this wonderful circuit. together. The S -M transformers used in the audio MARTIN PATREMIO, end give good reproduction, bringing out the low 93 Burns Atenue, Lodi, New Jersey. notes especially well. As to its DX ability, a feature which I suppose appeals to the majority of home set constructors- TONING DOWN A HORN the aerial used is outside, about 70 feet long and Editor, RADIO NEWS: 25 feet high. It was erected about four years ago, I have done a little experimenting on horns and and sags so much that it looks like a half- circle exponential speakers, but have found nothing that when viewed from one end. There is also con- will equal my horn and cone together. First of all siderable local interference which renders DX I am going to tell you how I fixed my loud speaker. difficult; March was a blank in my log -book on It is very simple, as all you need is some candle account of interference. Here are some of the tallow and a paint brush. Melt the tallow and A SPLENDID CRYSTAL SET distant stations heard: WONT, WMBJ, KEX, apply on the inside of the bell of the speaker. if Editor, RADIO NEWS: K\VK, I:WUC, WIOD, RAIT3C, KGA, KUOA, the unit of the speaker has a ringing sound. apply After building the set shown in the enclosed KQW, KPXF, KiIOX, ROiL, KO:\, WJAD, some of it on the inside of the cap. This, with the photographs (herewith reproduced) I am inclined KFAB, KFQB. KWKH, WDAF. CFCN. NEAP, cone, gives a pleasing tone, so that you can hear to believe that the radio amateurs are overlooking WFAA and KGO. Station KEX, 240 meters, every word of speech. I have built an exponential some of the possibilities of the crystal set. That was tuned 'in while WCAH (234 meters, hut ap- horn, described in RADIO NEWS, and it works fine, shown was built around a carborundum stabilizing parently higher) and WEDC (242 meters) were but I can't see that it does better than the combi- unit, and nude as compact as possible. The hexag- broadcasting. I have found KFI the easiest coast nation I have.

www.americanradiohistory.com Radio News for July, 1928 53

Some people think they are getting DX when The parts required are one double -pole double- they get Europe; but I think they will be sweating throw jack switch and two tip jacks. Cut the blood before they get KFSG, Los Angeles. I have plate lead from the detector as indicated at one talked with some people who have powerful sets X in the diagram, and the "B +Det," as shown, at and boast of KFI, but let them try and get the the other X. Extend the "B" lead on the first above station. MURRAY COLEMAN, A.F. transformer to the second prong from the top Spring Valley, Minn. of the jack; the "P" lead on the same to the second prong from the bottom; the "P" lead from the detector socket to the third prong from the A HANDY PHONOGRAPH SWITCH bottom of the jack; and the "B +Det" lead from the battery to the top prong. The two remaining Editor, RADIO NEWS: prongs are connected to the pin -tip jacks at the I read an article in the April issue on how to rear of the sub -panel for the pick -up connection. make a permanent hook -up of a phonograph pick -up Either the radio or the phonograph can now be to a receiver. I am enclosing a diagram of how played at will by throwing the switch. I have mine connected. receiver is a five My -tube Perhaps some other fans would be glad to use affair, and I have it built into a large upright this idea if you care to print it. phonograph. I tore out the horn and record M. A. PORTER. shelves; and in place of the former have a 7 x (Will Mr. Porter scud in Isis addressf- EmToa.) 18 -inch panel; while in the record compartment I installed a stripped 18 -inch Temple drum he- hind a home -made grille. I use a Pacent "Phono- SUCCESSFUL DX EXPERIMENTS vox" and run the cord through the tone arm Editor, RADIO NEWS: down to the pin jacks on the sub-panel. A snap I have experimented with different types of of the switch on the radio panel allows the use power tubes, and with wavetraps, and I find that of either phonograph or radio at will. A convenient radio -phonograph combination suvi ck (Continued on page 89)

List of Broadcast Stations in the United States (Continued frosts p(lge 28) ,- Radio ú « Radio : ú« Radio o : Radio Call BROADCAST STA. Á« Call BROADCAST r, ú 3% STA. oat t n Call BROADCAST STA. Á« 3% Call BROADCAST STA, ¡.. A; Letter >: Location G,- Letter Location 3f y;° Letter Location 3 y;° Letters Location 3vi C;

WJBU Lewisburg, Pa. 214 100 WLS }Chicago * *345 5000 WOAN Lawrenceburg, Quincy. WJBW New Orleans, La. Ill Tenn.. 240 500 WRES Mass 217 Al 238 30 WLSI Sec WDWF WOAX Trenton, N. J...... 240 500 WRHF Washington,D.C.(day) 322 WJBY Gadsden, Ala 234 50 WLTH Brooklyn 151 N Y 256 250 WOBR Shelby. Ohio (portable) 204 10 WRHM [Minneapolis, Minn 261 1001 WJBZ Chicago Heights, III., 208 100 WLTS Chicago Ill 484 100 WOBT Union City. Tenn..... 205 15 WRM Urbana, WJJD Mooseheart, IU * *366 1000 nl.. 273 601 WLW [Cincinnati Ohio 428 5000 WOBU Charleston V . Va.... 268 250 W R K Hamilton, Ohio 205 10 WI KS Gary, Ind 232 500 (Also 52.02 -49.96 meters 250 watts) WOC Davenport. WJR -WCX Iowa 375 5000 WRMU NewYork.N.Y. (port ) 201 10 [Pontiac.. Mich 441 5000 WLWL [Kearny. N. J. 370 5000 WOCL Jamestown N. Y 224 25 (2XAO, ship. 105.9 meters, 100 (Also 32 meters. 75 watts) WMAC Cazenovla, N. Y 225 500 watts) wJZ York, WODA Paterson. N. J 294 1000 WRNY [New York, N. Y 326 50 ¡New N. Y.... +*45430,00 WMAF So. Dartmouth, Mass 428 500 W01 Ames, Iowa 265 100 (Also 30.91 meters, 500 watts) (3XL, 59.96 meters, 30 k.w.) WMAK *Martinsville N. Y 545 750 WOK See WMBB WRR Dallas, Tex 461 WKAQ San Juan. Porto Rico 322 500 WMAL Washington D. C 24.2 500 WO KO 50 Beacon, N. Y 216 500 WRRS Racine. Wis .. 248 51 WKAR East Lansing. Mich 278 *50 WMAN Columbus. Ohio 234 50 WO KT Rochester. WKAV Laconia. N.73 N. Y 210 500 WRST Bay Shore, N. Y 211 15 224 50 WMAQ Chicago, Ill * *447 250 WOMT Manitowoc. Wig 222 100 WRUF Gainesville, Fla 203 500 WKBB Joliet, III 216 150 WMAY St. Louis, Mo 234 100 WOO Philadelphia WKBC Birmingham. Ala Pa 349 500 WRVA Richmond. Va 254 100 219 10 WMAZ Macon. Ga 270 500 WOOD [Grand Rapids, Mich 261 500 WSAI [Cincinnati, Ohio 361 500 W KBE Webster. Mass 229 100 W MBA Newport. R. I 204 100 WO Q Kansas City, Mo 341 500 WSAJ Grove City, Pa WKBF Indianapolis, 252 WMBB 224 25 Ind 250 [Chicago, ill 252 5000 WOR [Kearny, N.J 422 5000 WSAN Allentown, Pa 222 10 WKBG Chicago, Ill. (portable) 201 100 WMBC Detroit, Mich 244 100 (Also 65.4 meters, watts) 500 50 WSAR Fall River, Mass 213 25 W K B H La Crosse. Wis 231 W M B D Peoria Heights. III 205 230 WORD [Batavia. III 252 5000 W SA X Chicago, WPM Chicago, 216 Ili. (port.) 204 10 Ill 50 WMBE WhiteBearLake Minn 208 10 WOS Jefferson City. Mo 422 500 WSAZ Huntington, W. Va 250 10 WKBL Monroe, Mich 205 15 WMBF Miami Beach. FIa 384 50 WOW Omaha, Nebr 508 1000 WSB Atlanta. Ohio Ga 476 100 WKBN Youngstown, 214 50 WMBG Richmond. Va 220 50 w0 WO Fort Wayne, Ind 229 +250 WSBC Chicago. Ill 232 50 WKBO Jersey City. N. J. 219 500 WMBH Joplin. Mo 204 100 (Also 22.8 WKBP Battle Mich meters. 1000 watts) WSBF St. Louis, Mo 258 25 Creek. 213 51) WMBI ¡Addison, Ill +253 5000 WPAP See WQAO WSBT South Bend, Ind 400 50 WKBQ New York, N. Y 219 500 WMBJ McKeesport, Penna... 232 50 WPCC Chicago, Ill 224 500 WSDA See WSGH WKBS Galesburg, Ill 217 100 WMBL Lakeland. Fla 229 100 WPCH York. N. Y 326 WSEA Portsmouth, WKBT New [New 500 Va . 263 50 Orleans, La 252 50 WMBM Memphis. Tenn 210 10 WPEP Waukegan. III 216 250 WSGH Brooklyn. N. Y 227 50 WKBV Brookville, Ind 219 100 WMBO Auburn. N. Y 220 100 WPG Atlantic City. N. J 273 5000 WSIX Springfield Tenn 250 15 WKBW Amherst, N. Y 217 50000 WMBQ Brooklyn, N.Y 204 100 WPRC Harrisburg, Pa 210 100 WS KC Bay City. Mich 273 25 WKBZ Ludington, Mich . 200 15 WMBR Tampa. Fla 252 100 WPSC StateCollege, Pa. (day) 300 500 WSM Nashville, W K D R 248 W M B S Tenn...... 337 500 [Kenosha. Wis 15 Lemoyne, Pa 234 250 W PS W Philadelphia, Pa 207 50 WS M B New Orleans. La. 297 75 W KEN [Buffalo, N. Y. 207 750 W M B W Youngstown. Ohio 214 50 WPTF Raleigh, N. C 545 1000 WS M K Dayton, Ohio 297 20 W KJC Lancaster, Pa 252 50 W MC Memphis. Tenn. 517 5000 WQAM Miami. Fla 381 750 WSPD Toledo. Ohio WKRC Cincinnati, Ohio 246 500 240 25 WMCA [New York, N. Y 370 500 WQAN Scranton, Pa . 231 250 WSRO Middletown. Ohio 236 10 WKY Oklahoma City, Okla 288 150 WMES Boston, Magie 211 50 WQAO -WPAP tCliffside, N J.. 395 500 WSSH Boston, Mass 288 10 W LAC Nashville, Tenn 225 5000 WMPC Lapeer, Mich 234 30 WQBA Tampa, Fla 238 250 WSU I Iowa WLAP 268 500 WMRJ City, Ia. (day) 476 50 Louisville, KY Jamaica. N. Y 207 10 WQBC Utica, Miss. (day) 216 225 WSUN St. Petersburg. Fla 517 75 WLB Minneapolis, Minn 246 500 WMSG New York, N. Y 236 500 WQBJ Clarksburg, WLBC W. Va 240 65 WSVS Buffalo, N. Y 204 5 Muncie. Ind 210 50 WNAC -WBIS Boston, Mass 461 5500 WQBZ Weirton, W. Va 250 60 WSYR Syracuse, N. Y 294 50 WLBF Kansas City, Mo 210 50 WNAD Norman. Okla 240 500 WQJ Chicago, WLBG Ill 447 500 WTAD Quincy, Ill 236 25 Petersburg, Va 214 100 WNAL Omaha. Neb 258 250 WRAF Laporte. Ind 208 100 WTAG Worcester. Mass 517 25 WLBH Farmingdale, N. Y 232 30 (Also 105 meters. 50 watts) WRAH Providence, R. I. 200 250 WTAM Cleveland, Ohio .... .* *400 350 WLBI East Wenona. Ill 238 250 WNAT' Philadelphia, Pa 288 100 (Has }Stevens short -wave transmitter) WTAQ Eau Claire, Wis 254 50 WLBL Point. Wise 333 1000 WNAX Yankton, S. D. (day) 303 1000 WRAK Erle, Pa 219 30 WTAR -WPOR Norfolk, Va 236 50 WLBM Cambridge, Mass 231 50 WNBA Forest Park, Ill. 208 20 WRAM Galesburg, Ili 248 50 WTAS Elgin, III . 275 50 WLBN Little Rock, Ark 204 50 WNBF Endicott, N. Y 207 50 WRAW Reading, Pa 238 100 College Station, wLBO Galesburg, 217 WTAW Tex... 484 50 Ill 100 WNBH New Bedford, Mass 261 250 WRAX Philadelphia, Pa 213 250 WTAX Streator, Ill 298 5i WLBQ Atwood, III 219 25 WNBJ Knoxville, Tenn 207 .50 WRBC Valparaiso, Ind. 238 250 WTAZ Richmond, Va 220 L WLBR Rockford, 248 15 WNBO Washington, Ill Pa 211 15 WRBH Manchester, N. H b0 WTFF Mt. Vernon Hills. Va 203 10.004 WLBT Crown Point, Ind 248 50 WNBQ Rochester, N. Y 205 15 WRBI Tifton, WLBV WNBR Ga 50 WTFI Toccoa, Oa.. 210 501 Mansfield, Ohio 207 50 Memphis, Tenn 2.29 100 WRBJ Hattiesburg 10 WTHS Atlanta. Ga 227 20 WLBW Oil City, Pa 294 500 WNBT Elgin. Ill. (time Sigo.) 35.5 500 WRBL Columbus, Ga WT IC Hartford, Conn 50( N B W 50 535 W LB X Long Island City, N.Y. 204 250 W Carbondale, Pa 200 5 W RB Q Greenville. Ga 100 W T MJ Mflwankee, Wig 294 10( WNBX Springfield, Vt 242 10 WTRL WLBY Iron Mountain, Mich 210 50 WNBZ WRBI Wilmington. N. C.... 50 Midland Park. N. J -207 11 WLBZ Dover-Foxeroft, Me 208 250 Saranac Lake, N. Y 232 10 WRBU Gavtonia, N. e 50 WWAE Chicago, III 227 50( ,r,0 WNJ Newark, N. J 268 250 WRRW Columbia. S. C` WLCI Ithaca, N. Y .248 (Has short-wave transmitter) 15 WWJ Detroit, Mich 353 100( WLEX Lexington, Mass 216 50 W RB X Richmond, Va 250 W W L New Orleans, WLIB WNOX Knoxville, Tenn 265 1000 La 246 50( See WGN WNRC Greensboro, N: C 224 250 WRC Washington. D. C... *465 500 WWNC Asheville, N. C 297 1001 WLIT Philadelphia, Pa 405 500 WNYC New York, N. Y 500 WREC [Memphis, Tenn 250 500 WWRL W LOE Chelsea, Mass 526 [Woodside. N. Y -20 10( 211 100 WO A I Can Antonin Tar °an ton- NI R i N T.nmpnnnn Iron sien u,we c»,.....,, ._ ,_ -... -. *Allowed higher daylight power. ...Standard or constant -frequency transmission. }Remote Control.

LIST OF CANADIAN BROADCAST CALLS

CFAC Calgary. Alta 435 500 C H C Y Edmonton, CFBO Alta 517 250 CJOC Lethbridge Alta 268 50 CKOC Hamilton, Ont...... 341 100 St. John, N. B 337 50 C H G S Summerside, P. E. I... 268 CJ OR Sea Island, B. C 291 50 C KO W Toronto, CFCA Toronto, Ont 357 Ont.... 517 500 CHIC Toronto. Ont 357 500 CJ R M Moose Jaw, Sask 297 500 CKPC Preston Ont...... 248 CFCF Montreal, Que 411 1650 CH MA Edmonton, Alta 517 250 CJSC Toronto, Ont 357 500 CKPR Midland, CFCH Iroquois Falls, Ont 500 250 Ont .. 268 50 CHML Mt. Hamilton, Ont.... 341 50 CJ WC Saskatoon, Sask 330 250 CKSH st. Hyacinthe. Que... 297 50 CFCN Calgary. Alta 435 1800 CHNC Toronto, Ont 357 CJ YC Toronto. Ont. 517 500 CKSM Toronto, CFCQ Vancouver, B. C 411 10 C H N Ont...... 517 1000 S Halifax, N. S 322 100 CKAC Montreal, Que 411 1200 CKUA' Edmonton, Alta 517 500 CFCT Victoria, B. C 476 500 CHPC Vancouver, B. C 411 1000 CKCD Vancouver, B. C 411 1000 Vancouver. CFCY Charlottetown, P.E.I 312 CKWX B. C 411 100 CHRC Quebec, Que 341 5 C K C I Q rebec, Que 341 23 CKY Winnipeg, CFGC Brantford, Ont. 297 50 Man 384 5ÓÓ CHSC Unity, Sask 268 50 C KC K Regina, Bask 312 500 CNRA Moncton, N. B 476 500 CFJC Kamloops, B. C 268 15 C H U C Saskatoon, Sask 330 500 C KC 1 Toronto, Ont. 357 500 CNRC CFLC Prescott, Ont 297 50 Calgary, Alta 435 500 C H WC Regina, Sask 312 15 CKCO Ottawa, Ont 435 100 CNRE Edmonton, Alta 517 500 CFMC Kingston, Ont. 268 20 C H W K Chilllwack, CFNB Fredericton, B. C. 248 C KC R St. George. Ont 258 25 CNRM Montreal Que 411 1650 N. B 248 25 C H YC Montreal, Que 411 750 CKCV Quebec. Que 341 50 CFQC Saskatoon, Bask 330 CNRO Ottawa, Ont 435 500 CJBC Toronto, Ont...... 517357 C KC X Toronto. Ont 517 500 CNRQ Quebec, Que CFRB Toronto. Ont. 517 10ÓÓ 341 50 CJBR Regina, Sack 312 5000 CKFC Vancouver, B. C 411 50 CNRR Regina, CFRC Kingston. Ont..... 268 500 CJCA Edmonton, Alta 517 500 Bask 312 500 CFYC Burnaby, B. C 411 500 CJCJ Calgary, Alta 435 250 C KG W BowmanvWe, Ont 312 5000 CNRS Saskatoon, Sask 330 300 CHCA Calgary, Alta 435 250 CJCR Red DeerDeer, Alta 357 CKLC Red Deer, Alta 357 1000 CNRT Toronto, Ont 357 500 CHCS Hamilton. Ont 1 341 10 CJGC London, 330 CKMC Cobalt. Ont 248 5 CNRV Vancouver, B. C. 291 500 CHCT Red Deer, Alta 357 1000 CJGX Yorkton, Sask 476 500 CKNC Toronto, Ont 357 500 CNRW Winnipeg, Man 384 500

www.americanradiohistory.com 54 Radio News for July, 1928

TELEGRAPH OR PIANO? NOT A MICROMETER A REAL INVENTION Help for the weary Interesting item from TH15 METER Something new in the Charlotte (N.C.) Ob- meters described in the diner -out is promised by WILL NEVER GO columns server of March 30th: tN TO MY SET': Radio Dealer, March, the advertising "Station WBT is at pres- 1924: "lt has a body di- of the Barnsvtlle (Ohio) ent operating on 1.160 ameter of 2 inches and it IVhetstoue of March 9: KEYS, 1,000 watts has an accurate movement "FOR SALE - Famous power." If it means that of the moving VAN R a d i o l a 16 six -tube, the station works on this type." Olt. yeh? Most of single dial, S PfJ P ER number of telegraph keys, nil( the moving vans we have SELECTIVE. Costs that will be news; but if met -to our sorrow - $145, will sacrifice for it operates on 1.160 dif- would hardly fit into any- $175." Seems as though ferent musical keys, that thing two inches in diam- these prices are a hit out, will he agony. eter. However, live and but if it will provide our Contributed by our old friend Anonymous. learn. -Contributed by W. F. Gamble dinner it is worth the cash. Contributed by 011ie Meloay OUR COIN FALLS OUT AT THE TOP HEY, MIKE, GET BUSY! In the New York Tele- SLIDE, KELLY, SLIDE! Herewith some excel- gram of March 24th we LOSE Scientific announcement lent advice from Harry find specified, in a list of SOME- from the Lansing (Mich.) Alter's Radio Book for parts for an amplifier, the THING? Journal of March 14, to 1928: this April "Buy peculiar item `Two UX the effect that ". . .. the BOO and your service POCKETS." These must famous HEAVY' LIDE will improve." We sent he the kind that develop layer in the atmosphere, Mike of the Investigation after a suit has worn 30 to 50 miles up," is Dept. around to find us a four or five years You "comparatively low boo or two; for some of know the kind - four down." This must be our apparatus hasn't been holes through tv hic h something like the slides giving us such good serv- everything drops. they have at Coney ice, lately, despite the Contributed by - o Island. Now we know many boos the baby tosses B. B. Bryant what happens to some of at it.-Contributed by Ruford W. Watson the radio waves; they're sliding around upstairs some place.- Contributed by R. C. Ditto C'MON, YOU VOLTS! F you happen to see any humorous mis- Pre -season f o o t b a l l prints in the press we shall be glad to have you clip them out and send to us. THAT AIN'T NO LADY - practice noted by the April 7th Radio World of Feb. 4: No RADIOTIC will be accepted unless the This from the printed original giving the name of the issue of Radio Doings: "One Powerful New Am- the di- plifier Tube BOOTS Sig- newspaper or magazine is submitted, with "The trio is under nal Strength in Circuit." date and page on which it appeared. We rection of Kola Levienne The Amps and the Volts will pay $1.00 for each RADIOTIC ac- and has as one of its . Webster will have a wild time cepted and printed here- A few humorous members MR. playing lines from each correspondent should ac- Hoover, M E Z O -S O- each other this company each RADIOTIC. The most hu- PRANO, director of pro- season, with so much re- morous grams for KJR." Accord. sistance affecting both ones will be printed. Address all elevens. RADIOTICS to mg to our way of think- Yey, Volts, kill ing. there are plenty of these Amps! I Editor, RADIOTIC DEPARTMENT, Contributed female sopranos without by George McArdle c/o Radio News. the men horning in. .,,,,,,,,,,,,...... ,,.,,,,,,...... ,,,,.,,,, ...... ,,,,.,,,,.....,,,,,,,,, Contributed by Brayton Shovers SPRIG HAD CUB Vernal gesture from UNLESS IT'S FIREPROOFED WE NEED THEE EVERY HOUR the Chicago Apparatus A rather warm one Financial note from the Company's catalog: `The found in the Memphis HOT sPeAHeR!! masts thy, Indianapolis Star are rustproof and Commercial A p p e a l of (':1 2 `,t of March 18: "The each one is equipped with April 8, `It consists of t1lt WLW BANKBOX hour a three roof anchors, 50 two l i n e n diaphragms z..- <-,_ ' ir) will open at 8:15 this ¡a feet galvanized GAY wire stretched upon FLAMES ` evening." Our readers and a puII, y." The with the centers drawn (xl who were anxious to flowers that bloom in the in towards each other." catch KMOX broadcast- ir- spring, tra la. remind the We're willing to wager '0 ing checks (of the chess- broadcast fart that house- the w e e k l y pay -check cleaning playinga tuned is now due; this against the w,k. doughnut able variety) were tuned goes for the aerial equip- that the timbre of this in, we hope, at the right ment as well -- Contributed by Caesar Crosby. speaker isn't so much. time to collect a few Contributed by A, Letzkus pleasant souvenirs of the occasion. Contributed by Caesar Crosby YOU MUST COME OVER! E PLURIBUS UNUM Queer program number The New South asserts A POSITIVE DRIVE found in the Boston Post itself, according to the Fashion note from the of March 18: "3:00 P.M. Jasper (Alabama) Eagle, New York Sun of April -Beethoven MALE Quar- which chronicles the pro- 7: "Workrite radio in tet. Etta M. Bradley, spective establishment of beautiful console with Soprano; Clara Killius, a "5000 KILOWATT BELT IN cone speaker." Contralto; W. D. Broad- station in Birmingham Whether this belt is in- bent, tenor; M. J. Dickin- that will be the equal of tended as a power -trans son, bass." Perhaps radio any station in America." former device for the male quartets are differ- As no station has now more speaker, or merely to hold ent from those ordinarily than a fiftieth as much its diaphragm from slip - found in churches and power, candor compels us ping off, we do not know; theatres, eh? to assert that this station but in either event, it Contributed by E. E. Gould will be equal to none. should be helpful out the Contributed by Wood -Rowe Purcell low notes. -Contributed by G. Bravard.

WE WANNA GO! IN THE SPRING A YOUNG MAN'S FANCY - ATTENTION, HAMS! A warm time promised Erotic motif in the Transmitting wrinkle by the Springfield (Ohio) South Bend (hid.) News- found in the Milwaukee Sun of March 6: "Thurs- Times of Feb. 26: "Rev, Telegram's "Radiolog ": day at 6:30 P.M. the Clarence W. Jones is on "An eighty MOTOR wave Sunset Boys are sched- his way to South America was found good for ranges uled to broadcast a SIN- where he will locate a site of 50 to 1,000 miles. If NER dance program. A for a I. O V E -\\' A \- E an operator using a low - TL\IL quartet are in- radio link to \V BT." p o w e r transmitter on cluded in this special en- Mike of the Investigation eighty MOTORS wishes tertainment." This sounds Dept. wanted to go down to communicate -" We like those parties that as a helper when he heard wish to inform the ex- Nero used to throw; or what kind of a station perimenting fraternity, maybe it was King was going up; but we de- owever, that this degree Arthur, if the quartet is in mail. cided to go ourselves. Do you blame us. of luxury involves some superfluity. Contributed by 011ie Meloay Contributed by Walter Hawkins Contributed by John Hopwood

www.americanradiohistory.com Radio News for July, 1928 55

TA

el f\ 1 1llltllRfi Grt1 -

Conducted by C. W. Palmer

RADIO NEWS readers send in every month an average of 5000 letters those asking for sketches, diagrams, data, etc., should send TWENTY. asking information on every phase of radio theory, construction and FIVE CENTS FOR EACH QUESTION : failure to enclose this will cause delay. operation. IVe 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 letters are not readable. Simple questions will be answered free; which is not a standard, published one, enclose a diagram to save delay.

,,,,,,,,,,,s... Alum ,.,.,tt,,,,tt...11, 1111 11411,41....,,,,.... , , ,,,,,,,,,,,,,,,,,,.... imenim,....,.,.,,..,.,....,.,,,,.,,.

LOCATING INTERFERENCE employed, since the receiver has to be portable in land or sea. These are usually found on the (Q. 2284). Mr. C. G. Shattuck, Juneau, Alaska, order to be of service. longer wavelengths. writes: "Radio fans in this city have recently "Triangulating" organized the Juneau Radio Club, with the per- STROBODYNE DATA In operation, the receiver is either carried or fection of local reception and the education of (Q. 2285). Mr. A. J. Drummer, Baltimore, Md., radio owners, so they will be able to better under- transported in an automobile, and the loop aerial is revolved until the sound of the interference is writes: 'Please answer the following questions in stand their sets, as our aims. the next available issue of RADIO NEWS. At "It was brought up at a meeting, some days at its maximum volume. The loop aerial is then pointed directly at the antenna of the interfering which frequency are peaked the long -wave trans- ago, that your magazine answered questions asked formers which are employed in the Strobodyne re- by fans. We would like information on the instru- set or other source of interfering noise. This operation should be repeated from several points, ceiver? Would it be of advantage to use two ments best adapted for finding squealers and other stages of radio -frequency amplification before the local interference sources. as shown in Fig. Q. 2284A. By laying off lines in the direction of greatest signal strength from Strobodyne receiver instead of one? Would it be each of the three or four points, the exact position advisable to employ a push-pull detector, like that of the source of the interference can be found. in the enclosed diagram, in the second detector The receiver should then he taken close to this circuit? Should the 201A -type tube be employed; LOOP indicated point, and moved around while the loop is rotated. It will finally be possible to move receiver way around location, the all the one with 00025 the loop continually pointed towards the center of A¡ ' 200A this small area. The cause of the trouble is IFT OSCILLATING somewhere near this point. It is then a simple RECEIVER .. , task to locate the exact source of the interfering CAUSING noise. INTERFERENCE Types of Noises RF.0 GRID Beside the regular howl of an oscillating receiver, INPUT LEAK '. there are several other noises which can be recog- TO /- nized when employing this device. Rapid and AUDIO - LOOP `. FREQUENCY regular clicking noises can, usually, be attributed AMPLIFIER to vibrating battery chargers or other electrical . devices which employ vibrators. Intermittent rasp- LOOP noises 200A ing and scratching which vary in intensity .00025 may be caused by defective insulators or loose con- tacts in power lines. A more or less steady and continual crackling noise may come from lamps Q2284A arc or some types of medical devices employing heat- A. Q2285 ing coils or arcs. A rapid whirring noise is usually L The source is caused by sparking at the contacts of commuta- of the sound where the loudest a loop readings center. It +nay he found more tors in motors, generators, etc. Crackling noises Circuit of push-pull second detector, suited accurate to take loop readings at points of least to the Strohodyne and other receivers with which occur at regular intervals are generally due 120 -kc. I.F. amplification. audibility, and lay off bearings at right angles to electric sign flashers. There are several other to the loop. noises which can be recognized, but the above are and should the grid return be to ''A -" or "A + "? the most common. Of course, the rather musical (A.) 'fhe intermediate- frequency transformers "We would be glad to hear from you on this long and short dashes which are often beard in employed in the Strobodyne receiver are tuned to a matter, as interference is sometimes very bad here, receivers, are due to radio- telegraph stations, on frequency of 120 kilocycles when the secondary coil and your help would mean a great deal to us." (A.) When locating oscillating receivers and other sources of interference, such as you mention Q2284 above, it is necessary to use a receiver which is entirely portable, yet sensitive enough and selec- tive enough to pick up signals from only one di- rection with a loop aerial. The set employed for this purpose must be completely self- contained, in- cluding batteries and all other equipment except the loop aerial. The cabinet enclosing the appara- tus must be. completely shielded, top, bottom and 1-3 MEGOHMS sides, with no openings at any point. 11 AFT A receiver for this purpose may comprise only d PHONES one stage of tuned -radio -frequency amplification, a .0005"'h .00025 .002 MF. óir non -regenerative detector, and one audio -frequency °d ti all stage as shown in Q. 2284. Of course, it is not 0005 20 !f! 10 necessary to use a receiver of exactly this type; OHMS OHMS B since any shielded set which is sufficiently sensitive 10 and portable will serve. The receiver illustrated em- OHMS ploys two tuning condensers, .0005 -mf. capacity, and a tuning inductor with 10 turns for the primary and 50 for the secondary, both wound on a single 3 -inch tube with about 1/4-inch spacing be- tween the two coils. A loop aerial sixteen inches square with 15 turns of No. 20 or larger wire with i SHIELD '/ -inch spacing between terns will he satisfactory. The values of the other apparatus are all indicated on the diagram. The "B" voltage should be be- Circuit of a three -tube portable set, adapted especially for the detection of "blooper?' and other tween 45 and 90; small "B" batteries should be sources of interference. It must be completely shielded, as indicated. See the test :,.r -:! data.

www.americanradiohistory.com 1928 56 Radio News for July,

-mf. Fig. 2286B shows bow a shielded choke coil can is shunted by a fixed condenser of .00025 dif- exact frequency, of course, depends be connected in the circuit to overcome this capacity. The wavelength of the dis- the accuracy of the condensers across the ficulty by changing the upon coil for this purpose may be secondary; and these condensers must be matched turbance. A choke few of No. 16 wire on a form very carefully, so that each of the intermediate - wound with a turns in diameter, and a small can mounted frequency transformers will be tuned to the same 14 inches over it. In some cases, a carbon resistor of about frequency. in place not suggest that you try to use two 20,000 ohms can be used as shown at C We would In this case, the shield is not stages of radio -frequency amplification before the of the choke coil. receiver, since this would involve the necessary. This method suppresses the interference Strobodyne than changes the wavelength. use of too many tuning controls and, if the tuning rather were ganged together, difficulty would It may be advisable, in some cases, to shield both condensers the high -voltage wiring running from the spark be encountered in keeping the circuits exactly in voltage and the low - resonance. The use of this extra stage would in- plug to the high- distributor, the size of the receiver considerably, too; voltage wiring from the distributor to the genera- crease volume noises. since it would be necessary to shield both radio - tor, in order to reduce the of the CONTACTS The methods mentioned above will be satisfac- frequency stages in order to obtain good results. A desire, you can employ a push -pull second tory for overcoming disturbances caused by the If you sug- in your set by the method that you sug- lighting installation itself but, naturally, these detector will not noises gest. (I'm the benefit of other readers, we are 50 OHMS froMNF6. gestions overcome interfering diagram to which Mr. Drummer refers, caused by apparatus connected to the line. These printing the types of since this should be of interest to many other noises come from a number of different If the 200A tube is used, it will be neces- COPPER OR apparatus, including fans, vacuum cleaners, violet - fans). irons, percolators, motors, X -ray sary to connect the grid return to the "A -". if ALUMINUM SHIELD ray machines, machines, etc. We would suggest that you read the 201A tubes are employed, the grid return should LEAD connected to the positive "A" battery terminal. SHEATH article in the March issue of RADIO NEWS entitled be Kill Radio Noises" in order to In order to obtain good results with this detector OVER WIRE "How to Vagrant system, it will be necessary to have tubes which overcome difficulties of this sort. A very inter- are matched closely, and also to adjust carefully esting booklet on this subject has been prepared the grid leaks; since the resistance on each side by the Radio Manufacturers Association, 1265 New York may be of the connection running to the filament must be Broadway, City and obtained bias from this organization for 25 cents. exactly the same, in order to keep the grid BAKELITE on each tube at the same value. TUBE A SIX -TUBE RECEIVER FARM -LIGHTING INTERFERENCE (Q. 2287). Mr. A. Klein, St. Louis, Mo. writes: (Q. 2286). Mr. A. F. Jensen, Stamford, Conn., (Q.) "I am writing for a class of thirty -eight writes: "We are having quite a lot of trouble with pupils at our school. We have bought quite a the 32 -volt lighting in- our radio receiver, because number of 17 -plate straight -line condensers and stallation which we are using causes a lot of also basket -weave coils of the Freshman type. interference. Since there are a number of relays Each of us wishes to build a radio receiver, one and spark gaps in this installation, we are at a loss for each room in our school. We have decided to know how to reduce this noise." on a five- or six -tube set, using three coils and (A.) The interference caused by a Delco or B condensers of the type I mentioned above. We similar generating plant may be caused by the 20,000-OHM wish to use two or three stages of radio frequency, spark at the spark plug of the gasoline engine, RESISTOR and two stages of audio -frequency amplification. We sparking at the distributor, sparking at the relays would be very thankful to you if you would publish and governing mechanisms, or motors or other ap- a diagram of such a circuit or send us one. If pliances connected to the installation. possible, we would like to use a loop aerial." There are three general ways of reducing this (A.) You will find here the schematic and pic- interference. First, the entire generating system 1, torial diagrams of a six -tube receiver employing may be enclosed in a metal box, being careful to the apparatus that you have on hand. As you will keep all of the wiring insulated and ground the notice, a loop aerial is used with four tuning con- box. Secondly, the disturbances may be eliminated densers and three radio -frequency inductance coils. by the use of condensers, resistors, etc., in the Two stages of transformer -coupled audio -frequency plant. Thirdly, we may change the generating CYLINDER HEAD amplification are used in order to give satisfac- frequency t.f the disturbances so that they will tory loud -speaker volume. not be annoying on the broadcast band. Fig. Q. 2286 shows at A how sparking at the Parts Required contacts in the relays may he prevented by shunt- The apparatus employed in the set is as follows: ing the contacts with a 1 -mf. condenser and a S0- C L, loop aerial (designed for a .00035 -mf. con- ohm resistor. In the case of the generator com- Q2286 denser); mutator, two condensers connected across the LI, 2, 3, radio -frequency choke coils; terminals of the brushes and the center point C, CI, 2, 3, .00035 -mf. variable condensers; grounded, will tend to prevent the disturbance. The Several methods for overcoming interference C4, .00025 -mf. fixed condenser, with grid -leak high -voltage wiring sometimes causes trouble, and caused by farm -lighting plants are shown above. mounting; the only way to overcome this difficulty is to shield At B is shown the method of constructing a C5, .002 -mf. fixed condenser; coil which is used for the purpose of changing C6, 7, 1 -mf. by -pass condensers; carefully all of this wiring and ground the shield. the frequency of the interference caused by Disturbances from the spark plug are some- the spark system. In this way it does not RI, 2, 3, 4, 5, filament ballasts, /s-' ampere type; times more severe on some wavelengths than others. interfere with reception on the broadcast band. R6, 20-ohm rheostat;

R8

VI L1 V2 2 V3 L3 V4 AFT 1 V5 AFT 2 V6

CD, ó °d LS ,CD

CS Q o e C3 T o°) ó -vvv+ 53 R4 RS R6 G°o

) ) ) ) o-oA8-So+ R7 C7 o A- C+

c B+ DET C6 B+ 90

o B+ MAX oC- Q 2287

This six -tube set contains the essential features of the most popular to a transmitter; and with a suitable power tube, will give ample volume commercial sets, t is easy to build and to operate; it is sufficiently for a large room. It is therefore recommended for construction and sensitive and highly selective, without shielding, when not too close use in schools. It does not require an outside aerial.

www.americanradiohistory.com Radio News for July, .1928 57

Q2287A

A+ A- B+ 84i 6M'C- L-S R5 L B- C+DET.90 C6 R4 rim_-ll: .!ii G ( iri' 41 .!, o. .(4'(i' IIIIMINI r - r F F+ F F. O O® ./ ' . . 1 V6 O ÄFT 2 ,,,,..,- r R1 >Oi Po. iÓ

Y YLii Y YL7i G Y F ( `u= 4Ya:Ìhf4d b1ykfYXS:NY.::1V.slw:ii'Ii: Y!:a. .!i:!S5; K ÌeN::!:q'r. M.v v; ffMJ'F!..aï.' .-.V6ÏÓÌJ]vÁ. ' i::J'ÌÌ V..1..-. ., C5 : « a « :: : . E ;;=;,..,: / a ma;._a . .. . ' /M / a .Y a a /. /n ..o1C a R6 C3 II im i' á mu irsr ii _im é ii iá ii /Y / p a soi a - a IN a._/m a .III Mi suii ii i .IDIINUItl' ñ w innXI/IIIAI ii ., ñ ! i --CC-/ --- . -'". Por l8 r'r '''h11111 OF "llulllllll _MN ` ''IIIIIIIIII

Layout for the six -tube set diagrammed at the bottons of rape 56. It should be easy to assemble.

R7, 400 -ohm potentiometer; short circuits by connecting the "A" battery, one obtain the constructional details for making the R8, 2- megohm grid leak; terminal to the "B -" and the other to the "11-F" transformer and choke coils to be used in this AFT', 2, audio -frequency transformers; terminals in turn. with the tubes in the set. If unit; since it is not very easy to obtain this ap- SW, filament switch; the tubes light when contact is made in this man- paratus designed for 25 -cycle current." VI to \-5, 201A -type tubes; ner, the wiring must be corrected. 1f it proves (A.) We have received a number of letters V6, 201A -type tube (or 112A- or 171A- type; see safe, connect the batteries in the proper manner, from our Canadian readers requesting constructional below) ; and proceed to operation. details for building 25 -cycle power -supply units. Six sockets, panel, baseboard (see below), eight It should be found that the four condensers give For this reason, we are including data for con- or ten binding posts and strips, wire, etc. almost exactly the same reading when tuning in a structing both the unit and the transformer and station -that is, if the loop used is of the correct chokes to be employed in it. The diagram of the Assembly design for the condenser used with it. If it is so power unit will be found in Fig. Q. 2288A. As The apparatus should be laid out on a sub - desired, the other three condensers may be ganged will be noticed, the unit has been designed to panel slightly shorter than the panel, and should together for simplicity of control. This, of course, employ an 85- milliampere tube and is provided be placed in the respective positions shown in the would necessitate changing the layout to corre- with two variable voltage output taps. This will pictorial diagram. A panel about 7x24 inches should spond with the mechanical coupling arrangement permit the use of this unit with any type of re be employed, and a baseboard about 23x8 inches. used, but the tuning will be much simpler, and very ceiver. Because of the lower frequency of this When the parts have all been mounted on the satisfactory results may be obtained. It is not current, larger chokes and condensers are re- panel and baseboard, the set should be wired. This advisable to attempt to operate the loop- tuning quired than with 60 -cycle A.C. should be done following either the pictorial or the condenser C from the same dial, however. In Fig. Q. 2288B will be found the construct"' schematic diagram, checking off each lead as con- The potentiometer R7 should be turned until no tioual details for the core of the power trans- nected, and all the wires should be run as directly whistles can be heard when the dials are rotated; former. This core should be built up of silicon` as possible, especially the grid and plate leads. the rheostat R6 should be turned up until normal steel .014 -inch thick. The "L" shaped laminations The connections should be soldered carefully, brilliancy is obtained on the detector tube. should be cut to shape, with either a hack -saw or either to soldering lugs or directly to the wire a cold chisel, and the edges should be filed down terminals. so that no sharp points will remain. A sufficient If a power tube is employed in the set, the "B+ number of laminations should be cut to make a A 25 -CYCLE "B" POWER UNIT Max" and "C -" terminals should be connected to pile 114 inches high for each side of the core. After the correct "B" and "C" voltages on the batteries (2288). 1lr. J. B. Roubidoux, Montreal, each lamination has been cut and its edges smoothed or plate supply. the voltages depending on the Canada, writes: it should he shellacked carefully with a thin coat of type of tube employed. If a power tube is not (Q.) "I would like to obtain constructional de- white shellac. This is for the purpose of insulat- used in the last stage, the "134 -Max" lead shown tails for building a "B" power unit for use with ing the laminations in order to keep the eddy cur- should be connected to "Bá-90 ", and the "C-" 25 -cycle current. I have noticed quite a few rents and heating effects in the core at a minimum. terminal should be connected to the negative articles on the construction of power units of this terminal of a 4% -volt "C" battery. type in RADIO News, but they are all designed Winding the Coils When the set has been completed and the con- for 60 -cycle current and naturally they are not The primary winding is placed over one of the nections carefully checked, it may be tested for suited for 25 -cycle supply. I would also like to (Continued on page 93)

The schematic diagram of the "Thermiodyne" receiver. of which massy Were manufactured and sold. Unfortunately, no data are available as to the coils. or the :.attic of the other Parts used in this set.

www.americanradiohistory.com ,58 Radio News for July, 1928

DraiorIlE?5 RADIO manufacturers arc invited o send to RADIO NEWS LABORATORIES meuls. No "write -ups" sent by manufacturers are published in these pages, 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 serv- pendent organization, 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 "What 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. w.mLLIZIM 1111. 11111111111n' un,,, vw,1.,111111iiiiii 111111IW WI D11,,,,nnuun,,.01.w1 u

FILAMENT SWITCH tretnely high, and with one amplify- and 2% inches in diameter, and cov- OSCILLATOR COIL stage, The "On and "Off" switch, sub- ing using 90 volts on the ers completely the tube and base. The oscillator coil (type 1 shown) mitted by A. F. Bulgin & Company, plate and 45 volts on the screen - It is made of red copper, with a submitted by the Mississippi Valley London, England, is a battery switch grid a voltage amplification of ap- bright lacquered finish; and is at- Radio Company, St. Louis, bio., is of the push -pull- button type. It is of proximately 40 has been obtained. tached to the sub -panel or base by of the plug -in type and designed for This amplification remained almost means of a molded bakelite ring use in radio receivers of the super- constant throughout the entire range mounted concentrically with the heterodyne type operating on an in- of the audio frequencies most used. socket. The top of the shield is intermediate frequency of 350 kc. The unit is hermetically sealed in provided with a removable cap, which This coil is wound on a tube l'fs an iron shell with a black crystalline makes it possible to attach the slot- inches in diameter and 23¢ inches finish. ted cap of the shielded connector to high, and has two sections, of 37 AWARDED THE RADIO NEWS the grid terminal at the top of the turns eath, spaced % -inch. The in- very neat appearance and faultless LABORATORIES CERTIFICATE tube. ductance value of the two windings operation. No noises duc to de- OF MERIT NO. 2346. AWARDED TiIE RADIO NEWS connected in series is 162 micro - are to be feared, as fective contacts LABORATORIES CERTIFICATE henries. A small rotor, i Vs inches contacts made by this switch are the A.C. FILAMENT TRANSFORMER OF MERIT NO. 2348. in diameter and tí -inch long, has almost perfect. approximately IO turns, and acts as The transformer ( "TCA No. 687" AWARDED THE RADIO NEWS a coupler with the rest of the circuit. LABORATORIES CERTIFICATE shown) submitted by the Trans- R.F. CHOKE COIL former .\ WARDED THE RADIO NEWS OF MERIT NO. 2344. Corporation of America, The choke coil (type C-60 shown) LABORATORIES CERTIFICATE submitted by Aero Products, Inc., OF MERIT NO. 2355. Chicago, Illinois, has an approximate VARIABLE CONDENSER inductance value of 6 millihenries The "Minerva Logarithmic" con- and a very low distributed capacity. denser shown, submitted by W. it is wound in three grooves on a Wohleber & Company, Vienna, Aus- wooden spool 1 inch long and 1% -inch tria, is a very -well -built electrical in diameter. The grooves are each instrument. Like most modern vari- approximately % -inch deep and %- able condensers, it is constructed al- inch wide, spaced 4 -inch. The most entirely of metal and has a very coil is housed in a neat bakelite shell, small amount of insulating material. and can be mounted by making one The stator and rotor are provided Chicago, Illinois, operates from the hole. with spacing bars, securing rigidity 110 -volt 60- cycle, house -lighting line, and permanency of calibration. A and supplies the necessary filament No. 2355 No. 2357 power for the operation of a radio receiver employing four to six tubes SHIELDED of the 226 type, a 227 -type detector, R.F. IMPEDANCE and one or two power tubes of the The "Braxton King" R.F. imped- 171 type. At full load, the meas- ance unit shown, submitted by the ured voltages have been found to be same manufacturer, is an interstage very close to their rated values. The coupling element, operating in con- 5 -volt winding for the power tubes nection with vacuum tubes of the shaft makes possible gang floating and the 2.25 -volt winding for the 222 type. It is intended to be used mounting, and a pigtail insures detector are center -tapped. This .\ WAARDED THE RADIO NEWS in the 350 -kc, intermediate- frequency noiseless connection between the ro- transformer is well built, and is LABORATORIES CERTIFICATE stages of radio receivers using the tor and the condenser frame. These sealed in a sturdy iron casing, 3%, OF MERIT NO. 2350. oscillator coil described under Cer- 23 have a maximum -plate condensers x 31 x 4% inches, of black crystal- tificate No. 2355. This impedance capacity of 483 mmf. and a mini- line finish. unit is of the plug -in type and con- mum of 13 mmf. As for its char- AWARDED THE RADIO NEWS SPEAKER sists of a coil, two fixed condensers acteristic curve, this condenser can LABORATORIES CERTIFICATE The "Seer's Speaker Chandelier" (coupling and tuning), a 2% -meg- be considered as a combination of OF MERIT NO. 2347. shown, submitted by Standard Compo ohm grid leak and a 15 -ohm fixed the two types of the SLF and the Works, Inc., Milwaukee, Wis., is resistor, all in one aluminum con- SLW. a combination of a chandelier base tainer serving as a perfect shield. AWARDED THE RADIO NEWS TUBE SHIELD AND SHIELDED The coil is of the single -layer type, LABORATORIES CERTIFICATE CONNECTOR wound on a tube 214 inches long OF MERIT NO. 2345. and 2% inches in diameter, and has an approximate inductance value of SCREEN -GRID A.F. IMPEDANCE 600 microhenries; across it is con- UNIT it? nected a .0003 -mf. tuning condenser, thus The "Z- coupler" shown, submitted forming the necessary plate impedance. by the Thordarson Electric Mfg. The coupling condenser has a value Co., Chicago, Ill., is an A.F. coup- of approximately .00012- mf. The ling unit of the double -impedance fixed resistor supplies the necessary grid bias. and a loud speaker; the latter is of .AWARDED THE. RADIO NEWS the air -chamber type, and made of I..\BORATORIES CERTIFICATE molded plaster reinforced by a fi- OF MERIT NO, 2357. brous substance. It is very attract- ive in appearance. and is designed for attachment to the ceiling in the A.C. TUBE center of the room. This speaker The A.C. tube (No. 127 shown) is equipped with a sensitive unit submitted by the Arcturus Radio The tube shield and shielded con- capable of handling a heavy output. Company, Newark, N. J., is of the nector (No. 322 shown) submitted The results obtained during the test five -prong indirect -heated type. The type, designed to operate in con- by the Carter Radio Company, Chi- of this speaker were satisfactory. normal operating voltage of the cago, junction with screen -grid amplify- Illinois, is designed to be used AWARDED THE RADIO heater 2.5 volts, with NEWS is although satis- ing tubes of the 222 type. The im- a screen -grid tube of the 222 i.ABORATORIES CERTIFICATE factory results were obtained over pedance value of this unit is ex- type. The shield is 5% inches high OF MERIT NO. 2354. (Continued on page 92)

www.americanradiohistory.com Radio News for July, 1928 59

BROADCASTERS So far, relay broadcast licenses have been is- verration on radio matters was heard from this OLD -WORLD sued where the sending of programs to foreign station. Mr. E. T. Somerset, of Sussex, England, con- countries or communication with a "central" or tributes the following information in regard to "master" station for purpose of rebroadcasting has shortwave stations heard by him: been desired. THOSE RUSSIAN STATIONS "I am appending a list of short -wave stations Marvin H. Thoreau, of Vancouver, 13. C., has that one can definitely listen to with a reasonable been unusually successful in logging foreign short- degree of success. all of which I have heard more wave stations. He tells of his experiences as fol- than once myself: 8GC, Paris on 61 meters; RFN, Station 2XAL's Schedule lows: "In a recent issue of RADIO NEWS, a reader Russia, on 60 meters; AGJ, Nauen, Germany, on refers to a short -wave broadcast station apparently 56.70 meters; SAJ. Karlsborg, Sweden, on 50 HE 30.91 -meter transmitter operated as RSN. This is really RFM, Khabarovsk, Si- meters; 1AX, Rome, Italy, on 45 meters; Vienna, by RADIO News broadcasts the same beria, not far inland from Vladivostok. RFM Austria. on 44.40 meters; Radio -Lyon, France, T program as that simultaneously given is now operating on approximately 70 meters and on 39.50 meters; AFE, Zeesen, Germany, on 37.65 by WRNY on 326 meters; its hours, in can be easily tuned -in at 2 A. M., (P.S.T.), any meters: PI BB, Iberakiken, Japan, on 37.50 me- Eastern Standard Time (add five hours for morning except Wednesday. Sometimes they can be ters: Radio -Vitus. Paris, on 37 meters; 6AG, Perth, Greenwich Time) are daily from 10:00 a. m. found earlier. Their program usually consists of West Australia. an 32.90 meters; 9XD, Zurich, until noon, and also the following afternoon news items, with musical numbers now and then. Switzerland, 32 meters; 3LO, Melbourne, 32.60 hours: On a recent Sunday evening they gave a special meters; ANE. Bandoeng (Java) Radio, 31.93 me- Mondays, 1:00 to 6:00; Tuesdays, 6:00 all -musical program shortly after midnight. RFM ters; PCJJ, Hilversum, Holland, 30.20 meters; to 11:00; Wednesdays, 1:00 to 8:00; Fri- is apparently using very high power and must LGN. Bergen, Norway. 30 meters; 2ME, Sydney, days, 1:00 to 10:00; Saturdays, 6:00 to he crystal- controlled. Signal strength is usually Australia, 28.50 meters; 5S \V, Chelmsford, Eng- 9:00; Sundays, 12:30 to 6:00. excellent. 5SW, of Chelmsford, England, comes land, 24 meters: PCLL, Kootwijk, Holland, 18 RADIO NEWS will be very glad to receive in almost daily front noon to 4 P. M., (P.S.T.), meters and AN H. Malabar (Bandoeng) 17 meters. and acknowledge all reports of the reception sometimes with loud- speaker strength. 2FC of "The following information may aid in tuning -in of this station, and especially the usual in- Sydney, Australia, on 28.5 meters, can often be stations. Station AFK, Doeberitz, Ger- formation as to reception conditions. In heard about 2 A. M. I have also heard Malabar, short -wave the many, on a wavelength of 37.65 and 67.65 meters addition to those from North American lis- Java; Eindhoven, Holland, and JHBB, Japan, announces the following in German: 'Kurzwellen- teners, letters and cards have already been latter on approximately. 37 meters. My receiving sender Anna Friedrich Karl.' The time to search received from amateurs and short -wave set set uses the usual plug -in coils and is an autodyne for this transmitter is between 6 A. M. and owners in British Guiana, Brazil, England, detector followed by two stages of intermediate of audio 2 P. M., E.S.T. France, I-Iolland. Portugal, Germany, Aus- frequency, second detector and two stages "Station 7RL at Copenhagen is owned by a tria, Czechoslovakia, Hungary, Morocco, In- frequency; six tubes in all and practically single - Danish newspaper and operates on a wavelength dia, Australia and New Zealand, and from control." of 42.12 meters. AXE, Bandoeng radio service, operators of ships at sea. "I used two Another reader, Dr. Roy M. Byram of Kangkei, Java, is operating on a wavelength of 15.93 meters tubes on you," writes Leo Nunn, of Kyogle, Korea, contributes the following information about and can be heard between 9:40 and 11:40 P. M., New South Wales, Australia, "and could the much -discussed Russian short -wave broadcast E.S.T. The Eiffel Tower, Paris, operates on a have got you on speaker on three, only I station; "Our best station is RSN at Khabarovsk, wavelength of 31.10 meters and can be heard did not want to wake up the family." Siberia. It comes in with volume too loud for I do not after 4 P. M.. E.S.T.^ Other acknowledgments have been made pleasure on my RADIO News set. As yet, elsewhere in these columns and by mail. have the wavelength. I should like to tell you, heard very clearly the broad- AUSTRALIAN 32 -METER While, owing to the "skip-distance" effect, though late, that I listeners -in within a few hundred miles of casting of the Stanford- Pittsburgh football games PROGRAMS -wave depend upon played in the Rose Bowl, Pasadena, California, to a short transmitter cannot Arrangements have recently been completed tuning it in regularly, occasionally it is on January 2. The program came over the WGY broadcast a weekly program over station 3L0, possible to do so; and we shall be equally short-wave transmitter. Since January reception 32 Melbourne, Australia. on a wavelength of gratified to have reports of reception of this has not been so clear." meters. By taking this step the Australian station station from nearby, as well as from around Charles Walton of Fresno, California, supplies hopes to establish a short -wave service for listeners, the world. Address the following with regard to the Russian broad- not only in the British Empire, but everywhere. cast stations being heard by our readers: "In reception have already been received EDITOR, RADIO NEWS, reference to your article in the April edition of Reports on 230 Fifth Ave., New York City, U. S. A. by 3L0 from listeners in various parts of the RADIO NEWS, page 1191, I beg to inform you that United States, Great Britain, Alaska, Japan, China, Mr. Blackington of Wrangell, Alaska, is right as India, Java and the Pacific Isles. All reports com- to the Khabarovsk station operating on a wave- ment favorably on the short -wave service, it is said; length of 56 meters. Also your Japanese friend, N. and it is hoped that each weekly effort will result, New Zealand listeners report hearing 4XD, the Miyake, is also correct; only that RFN is located not only in improved transmission, but in better short -wave transmitter of WSM, Nashville, Ten- at Moscow and is evidently a still more powerful reception brought about by these continued short- nessee, on 31.44 meters. station than RSN, as it comes in with much more wave experiments. South African listeners have been puzzled re- volume and the carrier -wave has greater strength. cently by a station heard calling "Hello, Japoni," I have been hearing both of these stations for some around 32.82 meters. Letters to the S. A. Wireless time as late as 6.30 A. M., (P.S.T.), but they OFFICIAL DUTCH TRANSMITTER Weekly suggest that it may be Peking, or the come in best around 4 o'clock. We on the coast A bulletin received from the press department of RFN is nearer 70 The Belgian Congo. However, considerable strength figure that the wavelength of the Netherlands Post and Telegraph Service, of signal was reported at Capetown. French con- meters." Hague, Holland, states that PCLL, at Kootwijk, has recently started programs of general interest on Holland and its possessions. The co- operation of the amateurs is requested in listening for this news, which la being sent out in four languages, The transmitter of the new 58.5 - Dutch, English, French and German. The trans- meter transmitter of 2XE, Richmond mission takes place every Wednesday between 7 Hill, Nrrc York, operated by A. H. wavelength of 18.1 Grebe & Co., and reproducing the and 8 P. M. (E.S.T.), on a broadcasts of WABC, New York. meters. This station is equipped with a beam Previous short -wave operations from transmitter, which, it is stated, reduces the angle this station were on a longer wave. of radiation to 30 degrees in its vicinity. A num- The small size and compact native ber of our readers have reported receiving speech of short -wave transmitting apparatus, and music from it. as compared with that of a long - toave station, may be readily seen. RELAY BROADCAST LICENSES There are now about 35 radio stations in the United States which are classified as "relay broad- cast stations," by reason of the fact that they transmit on short -wave channels for the purpose of pickup and rebroadcasting at some other point, often in a distant part of the world. Most of the relay broadcasting is done by stations regularly transmitting programs on wavelengths within the broadcast band. The numerous applications received by the fed- eral Radio Commission from additional stations seeking to broadcast simultaneously on short waves, in addition to their regularly- assigned waves, bas led the Commission to schedule this as one of the problems of future policy which will come in for serious con''4eration i the near future.

www.americanradiohistory.com 60 Radio News for July, .1928

Radiophone Short -wave Stations Stuttgart, Germany 42.00 coupling to the antenna circuit gives best results KDKA Pittsburgh. Pa 42.95 and uses a small fixed condenser in series with the (Hours reduced to Eastern Standard Time) LA Langenberg, Germany 43.90 aerial. This condenser consists of two metal plates Nauen, Germany 13.5 1MI Milan. Italy 45.00 one -half inch square, and one- quarter of an inch WNJ Ocean Township, N. J 13.88 IAX Rome, Italy 45.00 apart. KWE-KEWE, Bolinas, Calif 14.1 PCLL Kootwijk, Holland 45.00 H. Charrington of Hongkong, China, writes as AGA Berlin, Germany 14.9 WND Ocean Township, N. J 46.48 follows: "I have just completed a short -wave 2XG Rocky Point, N. Y 16.02 (Transatlantic phone) receiver something like the one described in RADIO The Hague, Holland ANH Bandoeng, Java 17.30 PCMM 46.50 NEWS. Last night, or rather this morning, I (Daily, 6 to 8 P. M.) SAJ Karlsborg, Sweden 47.00 tuned in 2XAF at 3:40 A. M., 2L0, London, at Konigswusterhausen, Germany 52.00 AGC Berlin, Germany 17.20 4 A. M., and PCJJ, Hilversum, Holland at 2:15 ANE Malabar, Java 17.40 WLW Cincinnati, Ohio 52 02 A. M. I was quite 3AR Melbourne, Australia 55.00 surprised at the quality of POZ Nauen, Germany 18.1 the music which I enjoyed very much." (Daily, after 9 P. M.) ANF Malabar, Java 56.00 PCLL Kootwijk, Holland.. , 18.70 AGJ Nauen, Germany 56.70 "In answer to your request for short -wave data," (Mon., Wed. & Fri., 7 to 8 P. M.) KFWO Catalina Island 57.03 writes Alvin Carlson of Gladstone, Mich.: "I JIPP Tokio, Japan 20.00 2XE Richmond Hill, New York 58.50 wish to state that 5SW, Chelmsford, England is (Daily, 4 P. M. to finish) 3XQ Bound Brook, N. J 60.00 now operating on a regular schedule from 1 P. M. JKZB Tokio, Japan 20.00 9XU Council Bluffs, Iowa 61.06 to 6 P. M., (C.S.T.), which is 7 P. M. to 12 P. M. (Alternates with JIPP) KDKA East Pittsburgh, Pa 62.50 London time, daily except Sundays. They come in PCTT Kootwijk, Holland 21.00 2XBA Newark, N. J 65.18 with very good volume but, for the last three days, 2XAD Schenectady. N. Y 21.96 6XAI Inglewood, Calif 66.04 there has been considerable high -speed fading of 2XE Richmond Hill, N. Y 22.10 RFN Khabarovsk, Siberia 70.00 their signals. I have heard them since March 21. WAJ-WEAJ, Rocky Point, N. Y 22.48 (Mon., Wed.. Sat., 4 a.m. on) My receiver uses two tubes in the Reinartz cir- (Transatlantic beam station) RDW Moscow, Russia 83.00 cuit. Mr. Beese was certainly right when he said Fort Wayne, Ind 22.80 7XAB Spokane, Wash 105.9 that announcements are very infrequent at 5SW. 2XAA Houlton, Maine 23.00 2XE Richmond Hill, N. Y 106.00 Another thing about this station is that they sign 5SW Chelmsford, England 24.30 6XBR Los Angeles, Calif 106.00 off at midnight, London time, by striking a gong Berlin, Germany 26.50 (Portable) twelve times and close down without any announce- KDKA Pittsburgh, Pa 27.00 1XY Tilton, New Hampshire 109.00 ment of call letters." PCPP Kootwijk, Holland 27.00 2ME Sydney, Australia 28.50 COIL SUGGESTIONS RFN Moscow, Russia 29.00 A number of useful constructional hints are (Daily 3 to 5 A. M.) BECAUSE of the experimental nature contained in a letter from A. E. Coatsworth of PCJJ Hilversum, Holland 30.20 of almost all radiophone work, and Thunderbolt, Ga., who writes as follows: "In 2XAL New York, N. Y 30.91 especially of all short -wave broadcasting, answer to your request in a recent issue of RADIO RFM Khabarovsk, Siberia 30.00 wavelengths, power, hours, and everything NEWS for some short -wave data, I have the fol- (Daily 5 to 7 A. M.) else connected with this list are subject lowing offer. am to change without notice. We especially to I a radio operator running Helsingfors, Finland 31.50 between the States and Germany and have a chance EH9OC Berne, invite all short -wave broadcasters through- Switzerland 32.00 out the world to send us the latest data to study the effects of different connections and (Mon., Wed. & Sat. 3 to 5 P. M.) on their transmissions ; and all bearers coils. I have tried all types of coils and have 2FC Sydney, Australia 32.00 who know of changes or additions to this found that, by winding them with No. 12 enam- CF Drummondville, Canada 32.00 list to advise us at once. By this means, eled wire (such as is used for aerials), I get EH9XD Zurich, Switzerland 32 00 short -wave listening can be facilitated for greater signal strength and a more rigid coil. I 3L0 Melbourne 32.00 all fans, who will know better what to wind the coil a regular fish EDITOR. on No. 6 dry cell and then JB Johannesburg, S. Africa 32.00 for.- remove same. The coil is space -wound and, for 3L0 Melbourne, Australia 32.60 separators, I use beads which will just slip over 2NM Caterham, England 31.50 the wire. The heads are staggered decrease 2XAF to the Schenectady, N. Y 32.77 spacing between the turns and are held in place (Tues. & Sat., 6 to 10.30 P. M.) Letters From Short -Wave Set Owners by thread. This makes a rigid coil and has noth- 7MK Copenhagen, Denmark 32.90 ing to cause an increase in capacity. (Tues. & Fri., 4 to 6 A. M.) AN 18 -METER STATION? 6AG Perth, West Australia 32.90 "For the tickler winding I use No, 26 D.C.C. (8.30 A. M. on) wire and bunch the winding to make it as com- A. L. Foss of Central Aguirre, Porto Rico, de- pact as possible. It is then placed inside the 6XAR San Francisco, Calif 33.00 sires information on a 18 station operating on heavy coil between the first and second turns, hold- Malabar, Java 33.00 meters and writes in part as follows: "Could you ing it in place with thread. I do not find this too XDA Mexico City, Mexico 34.00 tell me what station would be PCRR broadcasting at about close, and the set goes in and out of oscillation with Kootwijk, Holland 37.00 5.30 P. M., (E.S.T.), on about 18 meters? I a faint hiss as it is supposed to de. The radio- RA19 Tomsk, Siberia 37.00 have heard this station twice, distinctly, broadcast- frequency choke coil is another important part of Paris, France 37.00 ing music but no announcements. JHBB I also heard the set and, although quite a few writers say that Ibarakiken, Japan 37.50 a station broadcasting in Dutch PCUU The Hague, at about the same a number of turns of fine wire will answer, I find Holland 37.50 time on a wave of about 33 meters." JFAB Taipeh, Formosa, Japan 39.50 the best coil to be a long slim one. I use a com- Lyons, France 40.00 G. R. Sittler of Brooklyn, N. Y., has constructed mon cedar pencil with the lead removed. The 6XBR Los Angeles, Calif 40.00 the short -wave receiver described in the December, winding is put on the pencil after it is glued back (Irregular) 1926, issue of RADIO NEWS and reports hearing a together. I find that 135 turns of number 30 IAA Iwatsuki, Japan 40.00 number of American and European short -wave D.C.C. wire will cover the short waves and not SMHA Stockholm, Sweden 41.00 broadcast stations. He has found that very loose leave any "holes" in the tuning which cannot be changed with the antenna tuning condenser. A very small variable condenser is used in series with the aerial as it is very large. If the set is found to give trouble when going in and out of oscilla- tion, another turn should be added to the tickler coil, which will remedy the trouble. Another im- portant point is to put the tickler on the end of the coil which goes to the "A" battery and ground connection. "I can get WGY or KDKA, when lying at the dock at Hamburg, Germany, on the loud speaker, using but three tubes and 45 volts on the plate. KDKA fades. as seems to be its custom, but WGY is pretty consistent." A JUNK SET G. W. Robinson of Buffalo, N. Y., contributes the following: "after reading your article on the short-wave receiving set I threw a set together, using old discarded and '5 & 10' parts. It worked so well that I have never changed it. While writ- ing this I am listening to 5SW, England, broad- casting dance music on 24 meters. I consistently pick up this station every evening between 5:30 and 7 P. M., (E.S.T.), except Saturday and Sun- day, sometimes with enough volume for the loud speaker. You state in your April issue that PCJJ has moved from Eindhoven and is now listed as being at Hilversum. This I believe is in error as I have received this station a number of times and the announcement is 'Philips Laboratories, Eindhoven.' (The transmitter has been moved. -EDITOR.) This station comes in a couple of points below WGY, I should judge on about 30 meters. They do not seem to have a regular sched- ule, as I have heard them on Tuesday and This RADIO NEWS short -wave receiver, shown in a tropical setting, was built by A. C. Larson, of Thurs- day evenings between 7 the naval station at Guantanamo Bay, Cuba, and with a 210-type push -pull stage, operates two and 9 o'clock and then loud speakers with tremendous volume. Not only that, but its current supply is obtained from not heard them again for some time.- Recently I an automobile battery in the garage and a "B" power unit. (Continued on page 91)

www.americanradiohistory.com Radio News for July, 1928 61

CICHEREVER radio apparatus is demon- strated, note how the receivers equipped with Thordarson Transformers surpass in tonal reproduction. This year, more than ever before, fidelity of reproduction is the determining feature in the sale of the better radio apparatus. Since the musical characteristics of a radio instrument These quality instruments depend to such a great extent on a wise selec- are Thordarson equipped: tion of the audio and power supply transform- ers, it is significant that so many leading man- ufacturers have turned to Thordarson as the logical transformer source. Equally significant is the fact that not once since Thordarson transformers became available to radio manufacturers has any other transformer approached the manufacturer popularity of Thordarson.

PrestOLite RAdlodyNE nlwu, flORDARSON Buckingham RADIO TRANSFORMERS MURDOçK WALBERT mñ ,, 411h\r Supr ARGUS [JDI.L musical performance ERfpA Thoadarson transformers are universally available to custom crners set builders as well as manufacturers. Wherever radio parts are many sold, there you will find a complete stock of Thordarson Audio and Power Supply apparatus. If you are building for real musical performance, insist on Thordarson Transformers.

THORDARSON ELECTRIC MANUFACTURING CO Transformer SAecialists Since 1895 WORLDS OLDEST AND LARGEST EXCLUSIVE TRANSFORMER MAKERS '?turon and Kingsbury Streets -- Chicago.Ill. U.S.A. 3681

www.americanradiohistory.com 62 Radio News for July, 1928 Improving Reception on a Thin

RADIO NEWS AMATEURS Pocketbook (Continued front pale 46) HANDROCK rests flat against the wall; if it does not, You will see practically no difference in change the length of the cord or the posi- reception above 50 on the dial but, below tion of the screw -eyes. The latter will prob- that point, the middle dial will be found ably do the trick. much sharper, and the volume will be ma- When the unit is satisfactorily located, terially increased. At about 20, you will slip the stylus through the apex, and hold hear a click, and a little regeneration will the cone in place over the unit. 'Turn on be present. This can be easily controlled by the set and leave the thumbscrew on the the left -hand rheostat. What we have done apex loose. Slowly move the cone, until is to allow this one stage to be unbalanced you hit the spot where the music is the most slightly and to regenerate. Do not try to distorted and least audible; this is the short both resistors, for it will throw the proper position of the cone. It is now circuit too far out of balance, and the im- centered over the stylus, without placing proved results will not be worth the added any tension on it. difficulty of tuning. Get someone to hold the cone in this Now, for those who like the (listant sta- position for you, letting the set run so that tions, and want something even better, the any slip will be detected. Carefully drive following is advised, even though this is a a talking- machine needle through the top little more trouble. Get a 50,000-ohm vari- edge of the cone at the center. Let this able resistor and a 1 -mf. fixed condenser. needle extend out only about 1/16 -inch. It Cut a hole in the back of the cabinet, just 1?4YITECHNICAI. will hold the cone securely because of the above the battery connections; make this friction between it and the heavy paper, and just large enough to allow the whole resistor RAD10 FANS will be practically invisible, except on the to slide through. 'Take a piece of Bakelite, closest inspection. The music should now just large enough to cover this hole and THE RADIO NEWS AMATEURS' be just as distorted as before. leave room for mounting screws, and fasten HANDIBOOK is an invaluable guide Now tighten the thumbscrew on the apex to it the resistor in the usual manner; attach and reference book for every radio and get a treat. People owning A.C. sets the bakelite to the back of the cabinet, over enthus?ast. The most complete work with up -to -date cones have repeatedly ad- the hole, with four screws. Fasten the con- of its kind ever published. Every mired the beauty of tone and volume of denser to the inside of the cabinet along- this simple worthwhile development, since the be- arrangement connected to the side the resistor. Connect the condenser receiver shown. It seems to reproduce the directly across resistor with two pieces ginning of Radio can Le found some- the human voice, especially, with realism. After of copper wire. where within its pages. listening to a horn, it will be a revelation to Now remove the panel from the cabinet Radio Amplification; Audio Amplifica- hear the bass notes and to be able to dif- and short Loth of the little resistors on the ferentiate between the instruments in tion Power Amplification; "A and B" an condensers. Determine which binding post orchestra. - Power Circuits; Electric is the "B+ Amp "; you will find a short Sets; Short No doubt the use of an output device has piece of wire connecting this post with one Transmission Wave and Circuits -each now occurred to you. They do improve of the speaker posts. A green wire will of these important phases of Radio and tone somewhat, but they are not necessary be attached to either of these, and a brown many others are completely covered in with a unit such as this. Although the wire which goes back to near the panel and this remarkable book. writer has tried output devices on his set, then down to the H.F. tubes. With a he does not regularly use one; but would soldering iron, detach the brown wire from Radio Fans, Custom Set Builders, and recommend a good transformer rather than the post to which it is connected. Get two those studying Radio cannot afford to a choke -and- condenser filter. pieces of flexible insulated wire about eight be without a copy of this complete inches long. Solder the end of one of these handibcok on Radio. CHANGES IN THE SET to the brown wire and tape the joint se- Now that the audio end is fixed up, you curely. Solder the end of the other wire 112 pages -large magazine size may be interested in improving the selec- to the post from which you removed the replete with illustrations tivity and distance- getting ability of your brown wire. Replace the panel in the receiver. After trying wave traps, resis- cabinet and connect the two free wires to RADIO NEWS AMATEURS' HAND - tance- coupled radio frequency, choke -coil the two posts on the variable resistor. You now have another control, but it is IBOOK, the most complete chron- radio frequency, regenerative detector, etc., 1 eliminated everything but two simple necessary only to use it on distant stations. icle of Radio ever compiled. changes as impractical for the average It is really an oscillation control; by getting broadcast listener. I will describe the sim- the circuit near the point of regeneration, plest first. great amplification is obtained. For locals, THE 5 0 c COPY Remove the panel from the cabinet and tune in a local station of a low wavelength lay it on a table, dials down. As you now and adjust the resistor until the squeal AT ALL NEWSSTANDS look down at it, You will notice little fiat when tuning is just stopped. Leave it at OR WRITE DIRECT- (or round) strips, wound with very fine this setting for all locals. wire, on the backs of two of the variable I have been using this improved set as EXPERIMENTER PUBLISHING CO. condensers. 'These strips are near the bot- described for a year and a half, and it 230 Fifth Ave. New York, N. Y. toms of the condensers, and at the right of most certainly is more than twenty dollars the coils. These are grid resistors for the better than the original. As for distance, purpose of stabilizing the R.F. tubes. Take I receive the West coast here in Jersey EXPERIMENTER PUBLISHING CO. a short piece of copper wire and shunt it with fair regularity. This has been re- 230 Fifth Ave., Now York, N.Y. across the resistor on the middle condenser; peatedly verified and witnessed, and all this Gentlemen: Enclosed and 50e.. for which kindly send in other words, just short this resistance was on the cone with fairly good volume. me a copy of the new. up-to-date RADIO NEW -S AMATEURS' HANDIBOOK. out of the circuit. Do not disturb the re- My aerial is seventy -five feet long, and sistor on the first condenser. Solder the twenty -five feet high. The purpose of the Name wire to hoth sides of the resistor to make article, however, is not to hatch some more is the Address a good connection. Put the panel hack in DX hounds. My ambition to improve the cabinet, hook up the wires to the bind- radio reception of Mr. Average Man, and City State ing posts, and the job is done. It takes I hope that it is at least a step in the right about ten minutes. direction.

www.americanradiohistory.com Radio News for July, 1928 63 Aluminum Contributes to Radio Lightness, Beauty, Finer Results

MANUFACTURERS Of the finest quency amplifier. It makes pos- THE leading manufacturers of IVI sets are using Aluminum sible more compact design. foil and paper fixed con- in constantly increasing quan- Aluminum performs these densers now use Aluminum foil tities. Their tests have demon- functions efficiently and adds because of its high electrical strated that Aluminum is the less to the conductivity and its great cover- one metal that most efficiently weight of the ing area (a pound of Aluminum meets the widely differing con - set than any foil .0003 inch thick covers ditions encountered in radio substitute met- 34,000 square inches). Terminals design. al. Moreover, it is easily worked can readily be soldered to Alu- Its lightness; its permanent into special shield shapes -cans, minum foil conden- beauty; the fact that it does not boxes or casings. Thus it pre- sers by a process re- rust or corrode; its high elec- sents few limitations of size and cently developed by trical conductivity; its efficient shape. Aluminum CompanyofAmerica. shielding quality; its "workabil- It allows the engineer great ity" -all are advantages that freedom to design his shielding AUMAC Die Castings of Alcoa combine to make Aluminum the to meet, ideally, the various re- Aluminum combine light- ideal metal for radio. quirements of his set. ness, strength, accuracy and high conductivity. They have IN many of the most advanced ALUMINUM is widely used for equal strength with less than receiving sets Aluminum variable condenser blades. half the weight of other casting Shields are used to achieve better Aluminum Company of America materials. They are used with tone quality, produces special sheet Alumi- complete success for loud speak- greater selec- num for this purpose that is ac- er frames and bases, condensers tivity, closer curate and uniform beyond any- and condenser frames, drum tuning -in thing hitherto attained. Gauge dials, chasses -and short, finer reception. tolerance in even for cabinets. Aluminum shielding reduces thickness is There is a fund of in- interference. It eliminates elec- ±.001 inch and formation on the use of trostatic and electro- magnetic the total variation within one Aluminum in radio,and interaction between various sheet is limited to .0005 inch. on radio in general, in stages of radio -frequency am- Aluminum Company ofAmer- the new edition of plification. It eliminates modu- ica also makes finished con- "Aluminum for Radio." Your lation of radio frequency stages denser blades from this highly copy of this interesting book by feed -back from audio -fre- accurate and uniform sheet. will be mailed on request.

ALUMINUM COMPANY OF AMERICA ALUMINUM IN EVERY %COMMERCIAL FORM 2467 Oliver Building ALUMINUM Pittsburgh, Pa. ALUMINUM 7he mark of Qualitq in Radio

www.americanradiohistory.com 64 Radio News for July, 1928

...... ,N, '11 IIIUIU(P/O ,,q,,,,! A Sturdy and Dependable "B" Power ill' %', - ., Iti,a III lI ,, Unit - A// (Continued from page 43)

adjustment of the air gaps of the choke One iron -core choke coil; 10- milliampere, coils is the third method of eliminating hum. 30- henry, L3; To adjust these gaps, loosen the four bolts Two filament rheostats; 3 -ohm, 1.5 ampere, of each choke coil and place strips of paper RI and 112; in each gap of the core (there are two Two potentiometers, 400 -ohm, 113 and R4; gaps in each core) to serve as separators; One potentiometer, power type, 5,000-ohm, -in all its phases! then tighten the bolts. By experiment it R5; is possible to determine the amount of One fixed resistor, center -tapped wire- Complete instruction course in three paper required. wound type, 5,000 -ohm, R6; volumes. Every point of aviation effic- Before concluding this article it is neces- One fixed resistor, wire -wound type, 10,000 - iently and thoroughly treated. Subjects warning: namely, if ohm, lt7; covered in these volumes- sary to include one the plate of the rectifier tube becomes red - One fixed resistor, 100,000 -ohm (to protect hot, there is something wrong with the the filter condensers from the high po- MODERN power unit and the power should be turned tential developed if the high- voltage AIR CRAFT off immediately. Also, the power should plate circuit opens. It may be omitted not be turned on again until the defective if desired), R8; 700 Pages piece of apparatus has been discovered. Three filter condensers, 4 -mf., 1,000 -volt, Cl, ?AIR CRAB in such a case that C2 and C3; 500 Illustrations Usually it will be found 1, one of the filter condensers requires replace- One UX tube socket; ment. One rectifier tube, 216B or 281 type, V1; Contents of each chapter- of the Nine battery dips; I. Aircraft Types. II. The following is a complete list Lighter - than -Air Craft. apparatus required for the construction of One baseboard, 11 x 17 x / inches; ..,< HI. Early Airplane De- One front panel, 7 x 18 x 3/16 signs. General Design the power unit: bakelite Considerations. One power transformer; 110- 118 -125 -volt inches; \\ sign structio not rolls flexible insulated hook -up Aerofoils. V. Arrange- primary, two 8 -volt 2/- ampere second- Eight of ment, Fabrication and Bracing of Airplane Wings. VI. ary windings and one 525 -volt 60- milli- wire, white, salmon, brown, green, black, Fuselage and Landing Gear Construction. ampere secondary winding, T1; blue, yellow and slate. (This code cor- VII. Airplane Power Plant Types and Installation. VIII. Aviation Engine Design and Construction. Three iron -core choke coils; 60- milliampere, responds with the Neutroheterodyne di- Air-Cooled Engines. IX. Aviation Engine Design 50- henry, 300 -ohm, Ll, L2 and IA; agram given in the preceding article.) and Construction. Water -Cooled Engines. X. Avia- tion Engine Auxiliaries. XI. Aircraft Propeller Construction and Action. XII. Airplane Equilib- rium and Control Principles. XIII. Uncrating, Set- ting Up and Aligning Airplane. XIV. Inspection and Maintenance of Airplanes and Engines. XV. De- tails of Modern Airships and Airplanes. XVI. Sea- planes, Flying Boats, Amphibians and Other Air- craft. XVII. Some Aspects of Commercial Aviation. A Simple Remote -Control Device XVIII. Aircraft Instruments and Aerial Navigation. XIX. Standard Nomenclature for Aeronautics (Continued from page 49) Report No. 240, Part I. This book is written in simple, understandable language. Here, in order to keep the 110 -volt circuit probably be best for this purpose. The wir- PRICE $5.00 out of the remote control, a small "local" ing, too, will have to be changed, for the AVIATION battery (several dry cells) is used to actuate (comparatively) lightly- insulated material ENGINES the relay. This doses the 110 -volt circuit, used for the battery cable will not be very the current of which, in turn, passes through to carrying this higher voltage. This treatise. written by a well adapted recognized authority on all the primary of the transformer, the sec- Then, too, it is necessary to keep the wires of the practical aspects of Internal combustion engine ondary windings of which heat the filaments handling this current entirely separate from construction. maintenance. Of course, the use of a and repair, fills the need of the A.C. tubes. those carrying the loud- speaker circuit, as as no other book does. local in the relay circuit is not ex- The matter is logically battery their close proximity might cause a bad arranged; all descriptive mat- ceptionally good practice, because sooner ter is simply expressed and hum. copiously illustrated, so that or later the batteries run clown and then the wires the variable high resistor anyone can understand air- The to plane engine operation and relay will fail to work. It is for this rea- will be the same as those used in the others repair even if without pre- drawn. Here we vious mechanical training. son that Fig. 5 has been and they will be connected in the usual way. This work is invaluable !o of both set and anyone desiring to become have full A.C. operation The other three wires, though, will be con- an aviator or aviator mechan- remote control. The relay for use with a the trans- ician. nected to the lighting mains and battery should be of the high -resistance takes it 274 PAGES (PRICE $1.25 local former as shown. This, of course, type. will be necessary A. B. C. OF However, it AVIATION to make a few changes in the device, the most important one This book describes the basic principles of aviation, tells being the employment of a bet- bow a balloon, or dirigible is loado, and why It floats in the ter and heavier switch, capable air. Describes bow an airplane 110 -volt circuit flies. It shows In detall the of Itanclling the different parts of an airplane. trouble. A regular elec- what they are, and what they without do. Describes all types of air- tric -light toggle switch will planes and how they differ In construction, as well as de- tailing the advantages and disadvantages of different types of aircraft. It Includes a The remote- control box is complete dictionary of avia- the lo- tion terms and clear drawings opened here to show of leading airplanes. cation of the few parts and the simplicity of its construc- tion. At the left, the pilot PRICE $1.25 lamp behind its ewel; in the center, the 0.50,000 -ohm vari- Remit by cash, stamps, check, or money order able resistor which controls No C.O.D.'s tire volurse of the speaker or phones plugged in; right, the On All Books speaker jack. The combina- We Pay Postage tion shown here will allow the option of using phone CONSRAD COMPANY, Inc. plug or cord tips. 230 FIFTH AVENUE NEW YORK

www.americanradiohistory.com Radio News for July, 1928 65

S WHOLESALE PRiCES=11M1.1.1 ForVcdIers,Communh1qSet11uiIdeìy,General Repairmen and /?qent1Lc

Be sure to get this great 144 -page book with net prices to the radio trade. Radio Specialty Company is radio's oldest radio parts mail order house in the country, and the new confidential prices on standard radio merchandise are the lowest of any radio house. We are ready now to appoint additional agents in all parts of the country. If you are contemplating making big money in radio merchandise, be sure to get in touch with us at once.

EN LARGED EDITION rial THIS 144 PAGE RADIO

ILLUSTRATIONS 'CATALOGUE FREE ß4Lfrom *adioc Oldesi ?fliiil Orderlíouse! We are the oldest established, exclusive radio mail order house in the country. teous service. \Ve carry a larger variety of radio parts, radio instruments, All orders are positively shipped within twenty -four hours; quick, prompt, cour- accessories and radio findings than any other radio house in the country. You will find in Catalog No. 18 the largest assortment of radio merchandise in this country. Radio Specialty carries more radio parts and radio material than any other house in the country. You will find in this catalog positively the largest variety of radio merchandise. If you are in need of certain small radio parts that other radio and mail order houses do not bottler to carry get the Rasco Catalog and you will find the small parts there. anything from a screw to copper ribbon, tele, IVISCO''has it phone diaphragms, as well as thousands of other small radio findings. Just to mention a few: Lugs. nuts. jacks. plugs. all kinds of knobs, cords, panels, screws, sliders, washers. selenium. tinfoil, switches, crystals, cap nuts, Litz wire. cord tips, brass rods, resistances, binding posts. switch parts. carbon balls, switch points, lock washers, carbon grains, ground clamps. metal pointers, insulated tubing, low melting metal, antenna connectors. as well as thousands ANYTHING r,, of other articles. We carry the Largest Variety of Small Radio Parts in IN RADIO the World, BUT We also carry All Standard Radio Merchandise. f k\A\ 0 ' 98W PARK PLACE, NEW YORK

www.americanradiohistory.com 66 Radio News for July, 1928

for granted that the "B" supply device is fed from the same transformer that feeds RUBY 6V. MAZDA LAMP 50.000 - OHM the filaments of the A.C. tubes; if a sepa- ENS", AND MINIATURE SOCKET /VAR. RESISTOR rate eliminator is used, it should be con- nected in parallel with the filament trans- former in such a way that the switch in the remote control will work both together. This is not a difficult thing to work out. volume control in the remote- control 5- WIRE The BATTERY I CABLE STRANDED WIRE. EACH WIRE unit makes it possible to use a loud speaker SWITCH COVERING OF A DIFFERENT COLOR in one room and a pair of head receivers in another; because, by introducing more `TO SET OUTPUT resistance into the circuit, the volume may ABAI. INTERIOR WIRING -1u1-7éWitt) Ease TO SET BAT. FIG. 6

-.7 r-: ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,:, ,,,,,,, Above, the miring of the remote -control device in pictorial form. Its simplicity is seen at a glance. No specifications Note the special are given for the panel and box; as the symbol which had to to be designed to experimenter may construct them designate the Pert - suit his apparatus. That illustrated here d as no other is about six inches wide, two inches aracter in radio high, and two inches deep. Set in a practice properly It. wall, it is a neat fixture; or it may be idcetillyd L_ used as a portable control in the man- ,_J ner illustrated in the heading of this article. ,,,,,,,; II IB uií lldl IH -_- be reduced at one outlet only. The device the wires in the wall, with outlets as needed is so small that it may be conveniently in various rooms. The loud speaker may be e PERT DYNE placed on a table or the arm of a chair; carried about from room to room; or there the five -wire cable being run under a rug to may be a separate speaker on each remote Designed by the baseboard, where it may be stapled and control, which is more convenient in many HUUG GERNSBACK run to the set. The ideal way is to havé ways, if this luxury can be afforded. A One Dial Receiver! HE "Peridyne Five," because of new prin- k ciple employed in its construction, assures positive interstage resonance, and thus the of Third -Floor Quack EFFICIENT one dial receiver becomes a The Passing the reality. The Peridyne was designed by Hugo Gernsback, well known inventor and editor of (Continued from page 15) several popular magazines. Until the inven- tion of the PERIDYNE it was practically im- possible to obtain exact resonance between the RF stages of the Radio Receiver, due to the fact that the least little change in the tells -me to wait a few moments. A couple listens to my heart about ten seconds and spacing of the coil windings or the number of me. smiles. turns threw the particular stage out of reson- other patients are ahead of ance with remaining RF stages. Now, with It's half an hour before the White Sister "If all hearts were as sound as yours, Hugo Gernsback's Peridyne it is possible to Mr. Hammerstein, we doctors would be in adjust each stage of the receiver so that it will tells me to come in. The consultation room be in perfect resonance with each of the suc- is empty, but as soon as the nurse leaves the bread line shortly," he states. "You ceeding stages. This is the principle that have nothing to worry about on that score." makes the PERIDYNE the efficient receiver the Doc enters. that it is. "Mr. Hammerstein, of the Inanities last "'then I don't need a belt ?" me, you do not," he laughs, The season ?" he opens, and somehow I just can't "Sadly for PERIDYNE has again and again proven who its ability as a DX set, both in the summer help liking the guy. He's about thirty -five, "although there are so many do that months and in the winter. When built ac- it is a pleasure to find one whose most im- is -haired, athletic, and a handsome cording to specifications it one of the most brown properly." satisfying Receivers possible to obtain. cuckoo all told. portant organ is functioning Remarkably clear tone reproduction, selectiv- "And the fee ?" ity, and 100% efficiency-these are the high "My billing," I concedes. "Are you a lights of the Peridyne success. He waves me away. "I'm delighted to show fan ?" have met you, Mr. Hammerstein," he says, The Consrad Company, the oldest and original "Rabid," smiles the doctor. "What can Radio pattern publishers, have prepared a full shaking hands. "I shall make it a point set of blueprints, diagrams and specification I do for you ?" to attend your opening performance." sheets from which this remarkable Radio so opens Receiver can be built. Every question re- My part's all been gone over, I "I'll try to send you a couple of passes," garding the building of the PERIDYNE is with the customary recommendation. "One I if I run across anyone fully answered in the 16 -page instruction promises. "But booklet that is part of the Peridyne Pattern. of the girls in our chorus -My Radio Girl, who might benefit by your belt, I'll bring opening in a few weeks -showed me a radio he up myself to think of it, Write today -get a Peridyne or she -come Pattern -you are sure to belt of yours, and claimed it did her heart I do believe I know someone who'd be glad enjoy the results that the a great deal of good. I've a hunch my "Peridyne Five" will give you to try your apparatus." ticker may have been strained in some "Do so, by all means," he smiles, bowing Full constructional data dance numbers I did, and I'd like to get me out, and I'm halfway downstairs before one of your outfits as a safeguard." it dawns on me that I've been cottoning to The doctor nods. "I shall examine your a gyp. The fellow was so congenial - 50C heart, first, to see if you require treatment. "Well?" asks Jerry, when I meets him THE CONSRAD CO., INC. My belt is hardly a panacea; many cases at the drug store. 230 Fifth Ave., New York, N. Y. are too far gone for any earthly assistance. So I tells him the yarn. "And the funny If your organ is in perfect condition, the part is, the doctor seems to think he's legiti- THE CONSRAD COMPANY INC. belt would be of no value; to the contrary, mate. Most fakes will sell anybody any- 230 Fifth Avenue, New York N. Y. it might prove a detriment. The Tolman thing, but not this bozo. And such a pleas- ;entlemen: Kindly send me a full set of blueprints and all data required for building the new efficient Radio Breast Belt is primarily designed to ant mien-I promised him two passes, and Peridyne Receiver. Enclosed Ond 50e to cover. assist those whose heart action is inher- I'm going to see that he gets them !" ently sluggish. Too much electricity would, "Then you didn't get any technical in- Name of course, over -stimulate, and result in con- formation?'" asks The Master, disappointed. Address siderable strain. Therefore, the belt must "I'd have lost it before now if I had," be made to order for each individual." I answers. "He won't sell you a belt un- City State. A pretty speech, and it sounds sincere. less you need it-do you know anyone that If this guy's a crook, he's a genius. He has a weak heart ?"

www.americanradiohistory.com Radio News for July, 1928 hI

Dr . T .0' C On 01' Sloane will teach you.- CHEMISTRY Right in your own Home food Chemists Command High Salaries Industrial firms of all kinds pay tempting salaries to get the right men. Salaries of $10,000 to $12,000 a year are not unusual for chemists of exceptional abilities. Chemistry What Well -Known offers those who are ambitious and willing to apply them- Authorities Say selves conscentiously the greatest opportunities of any vo- About Our Course cation. Why be satisfied with small pay and hard, thankless work -learn the profession of Chemistry and your salary will From Hudson Maxim, depend only upon your "Dr. Sloane has done a much -needed own efforts and your own abilities. work in a much better way than any- thing of the kind has, heretofore. been The work of the chemist is extremely interesting. If you done. are fond of experimenting, if you like exciting and fasci- Dr. Sloane has a remarkable faculty nating work, take up Chemistry. To the man who is dis- of presenting Science for self -instruction of the student in such a clear and un- satisfied with his present job, to the young man just deciding derstandable way as to be most readily on his life work, Chemistry holds alluring charms and count- grasped and assimilated. less opportunities. If you want to earn more money, the "I. therefore, unreservedly recommend way is open through our course in Chemistry. and place my highest Indorsement on his work." From Dr. W. W. de Rerlor. "I can not recommend your course too NOW IS THE TIME TO highly and I congratulate both you and Dr. Sloane on same." T. O'CONOIt SLOANE. \ A.B., A.M.. LL.D.. Ph.D. From John A. Tennant. STUDY CHEMISTRY 11íb la something which has long Noted Instructor. Lecturer and been needed. Your long experience in Author. Formerly Treasurer Ameri- Never before has the world seen such splendid oppor- the teaching of chemistry . . assurance can Chemical Society and a prac- tunities for chemists as exist today. The war has awakened that the course will be practical as well tical chemist with many well known the United States to the need of trained chemists and chemi- as plain to the untrained students." achievements to his credit. Not only has Dr. Sloane taught chemis- cal engineers. Everywhere the demand has sprung up. In try In the class -room but he was factories, mills, laboratories, electrical shops, industrial What the Students Say: for many years engaged In oam- plants of all kinds, chemistry plays a vital part in the con- "Your course has been worth $50,000 mercial chemical work. tinuation and expansion of the business. In every branch to my concern." of human the need for chemists has arisen. No "This is just like reading some tas- endeavor cinating fiction story." profession offers such alluring opportunities and the next "I have just been made Assistant ten years are going to show the greatest development in this science that this country has ever seen. Chemist of my concern." Those who have the foresight and ambition to learn chemistry now will have the added advantages "Your course is lust what a person and greater opportunities afforded while the chemical field is growing and expanding. wanta to start in the wonderful science of Chemistry." "I find that your course is very 1n- tetesting. I wait patiently for the nest lesson." I find the study of chemistry more and more interesting at every lesson and You Can Learn At Homy you may be sure that I am getting Into studying habit even more than I ever Ability to Understand Plain English the Only Requirement did even in my school days." "I like the lessons so much that I hon- Dr. Sloane will teach you Chemistry in a practical and intensely interesting way. Our borne estly would not sell then. for many times logical and is illus- their price." study course written by Dr. Sloane himself is practical, remarkably simple. It I am taking this opportunity to express trated by so many experiments that are performed right from the start that anyone, no matter my satisfaction with your chemical lessons." how little education he may bave, can "I nosy have a arse position as chemist thoroughly understand every lesson. Dr. et the Du Pont Dye Works. It was titre Your course alone that I have been so Sloane teaches you in your own home 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 sneak very to Every Student thousands in highly of same." the class room. He will. "If I don't learn it isn't your fault for in addition, give you any individual help I find that your lessons contain a whole you may need in your studies. This per- lot." sonal training will be of inestimable value (Vaincs end addresses on request.) to you in your future career. DIPLOMA AWARDED TO EACH GRADUATE Upon graduation each student is awarded our Diploma in Chemistry, cer tifying that he has successfully completed his studies. Your name on this certificate will be a source of pride to you all your life, as well as an aid to obtaining a position in Chemistry. Easy Monthly Payments You do not have to have even the small price of the course to start. You can pay CHEMICAL for it in small monthly amounts or earn it as many others INSTITUTETUTE doing. The cost is very low, and includes even the Chemistry ¡ outfit -there are no extras to buy with our course. Write us and OF NEW YORKTUTE let us explain how you can qualify for a trained technical posi- tion without even giving up your present employment. Home Extension Division 7 MAIL THE COUPON FOR FREE BOOK 16 -18 -R -East 30th St., New York, N. Y. Your name and address on the coupon will bring you 0 We give to every student without additional charge. this by return mail our interesting free book, "Oppor- Please send nie at once, chemical equipment including fifty pieces of laboratory anpara- tunities for Chemists," and fall particulars about without any obligation on my tus and supplies and thirty -nine different chemicals and re- and what it will do for you. You owe part. your free hook "Opportuni- agents. The fitted heavy wooden box serves not only as a case the course ties for Chemists,' and full par - for the outfit but also as a laboratory accessory for performing it to yourself to get this book. Send the coupon ticulars about the Experimental Equip. countless experiments. Full particulars about this special right now while it is fresh in your mind. Or ment given to every student. Also please feature or our course are contained in our free book "Oppor- just write your name and address on a postal tell me about your plan of payment. tunities for Chemists." and mail to us. But whatever you do, act today. o Don't Wait -- Mail the Coupon NOW ! Á NAME CHEMICAL INSTITUTE of NEW YORK, Inc. ADDRESS 16-18 -R-EAST 30TH STREET Home Extension Division 7 NEW YORK, N. Y. CIT! STATE RN -7-28

www.americanradiohistory.com 68 Radio News for July, 1928

Jerry pauses in contemplation. "Several, got past the butler. Next morning we goes but I fear they would be unable to conceal in to consult the medic. the true motive of their visit," he says. I introduces Jerry as Mr. Gerard, and "Let me see, now, there's -why, how odd! the doctor examines him. I never thought of myself !" "Yes, you have a small ailment," he de- "You !" I exclaims. "Is your pump bad ?" clares. "One of my belts, under low pres- Dealers- "Nothing to be alarmed over," he replies, sure, will do nicely." "but my heart is naturally a bit sluggish." The sole piece of apparatus in the room for YOUR OWN benefit "Sluggish !" I repeats. "That's the very is a white chair, connected with nothing word- `those whose heart action is inher- except a somewhat larger replica of the ently sluggish'- you're it !" Doe's belts, this one being fastened to the Read...... Jerry muses again. "That's all very well, upper back of the chair, and equipped with but how am I to get in? He might not dials, gauges and controls. recognize me, but, on the other hand, should "This test is imperative, else one might he know who I am our purpose would be be killed while passing a large broadcast DEALERS lost. I'm afraid I'm out." station," lie explains, strapping the belt "Not at all, not at all," I disagrees. onto The Master, who's seated in the chair. "By I PERSONAL "Have you never heard of Sherlock finding your normal resistance, can Holmes ?" make a belt to conform to your particular "You mean a disguise ?" needs. Please tell me when you first begin ¡Editor: THE WHOLE RADIO TRADE I FDITIOÑ "Very keen," I applauds. "And I know to feel an electrical sensation over the the baby to do the job. Danny McKee is heart." the slickest makeup man that ever came Slowly he manipulates a few dials, and Mr. Dealer, if you are a wide -awake out of Hollywood. He even made Lon faint surprise registers on Jerry's made - merchant you will not want to miss this Chaney look like Lon Chaney" to -order face. Finally he says "Now." real trade magazine of the radio world The Master's not so certain about the "It is apparent at that point ?" -Radio News Dealers Personal idea. "Makeup for the stage is one thing, "Quite." Edition. In every issue you will find Joe, but when closely inspected -" "Now tell me when it ceases altogether." the latest verified developments of the "Drag along!" I commands. "You've Jerry does. industry. Each new angle of the never met Danny!" "Hm," grunts the doctor, reading a meter. game -new and old proven practices- I take him clown the Rialto to McKee's "A rather aggravated conditioh. You seem each is treated by one of your own costume shop, give the password and get insensible to shocks up to an unusually high into Danny's workroom. pressure. However, I shall you fellow dealers in every issue. This is private You may make a not be hep, but a lot of people sorta want belt, and later examine you to see if we a real trade paper. Different from a few changes made now and then, and cannot lessen the potential." any other going into the same field. Danny's the fair-haired boy they dingle "When will my belt be ready ?" The Radio News Dealers Personal when they need a new map. I'll concede "Tomorrow, but I have one here that is Edition is edited by the whole radio that most of his customers have been pho- slightly less powerful than you require. You trade. Editorially, Radio News tographed front and side, and a large part may use it until your own is ready. Be Dealers Personal Edition gives you of the others eventually will be mugged like - in at two o'clock and let me know what something impossible to obtain else- wise; you've got to be known to get into experiences you may have felt." where-the opinion and practices of his sanctum. The Master anti I drove to town in his the entire radio industry written by I've been friends with McKee for twenty closed laboratory truck, which is parked members of the industry itself -not years, ever since I was a kid with my old out of sight around the corner. We enters man's hard -shoe act, Danny's something by professional writers who must and it and Jerry quickly opens up the belt. It of an uncle to little Joe. He greets me in- consists of two small fixed crystal detectors, resort to a play on words rather than timately, although he kinda shies from The actual experience in preparing an a condenser or two, and about five hundred Master. turns of number twenty cotton -covered wire, authentic article. Until now it hadn't dawned on me that this latter terminating in two contacts that Jerry is a detective, connected with a fa- conic opposite each other when the belt is Read what your fellow dealers mous international agency, and as such not on, the heart being between the two ends. are doing. Send your order warmly welcome at Danny's. But I don't That's all. for a year's subscription. We mention it, and The Master's forgotten for "An elementary radio receiver!" snorts have made a special price the time being. Jerry. "Why, this thing couldn't produce for your benefit. $1.50 special "I require a temporary disguise," begins a shock -yet, I got one from that chair yearly subscription rate. Reg- Jerry, "one that will be quite 'convincing belt -well, I'll be damned !" ular price S2.50. Take advan- tage of this remarkable offer when closely scrutinized. It must neces- I keeps silent, and the next afternoon, now. Mail this coupon today. sarily take in my whole body at least down when we goes back to the office, The Master to the waist." slips me a gat, telling me to follow his lead. Danny looks him over. "Skin's the liard The doc ushers us in himself, this time, EXPERIMENTER PUBLISHING CO. part," he says. "But I can fix you so's you'll and brings out the belt. Jerry says he 230 FIFTH AVE., NEW YORK, N.Y. pass for forty. That do ?" wants to put it on now, so we goes. into the "Fine," agrees The Master. "Start at examining room. Quick as a flash the ATTACH YOUR LETTERHEAD once, please." Master makes a dive for a door behind the McKee's an artist, no fooling. First he chair, and before the doc can stop him WHEN MAILING COUPON he's - darkens Jerry's face and body to a rugged exposed the nurse and what proves to be THIS IS IMPORTANT tan, indicative of exposure to the elements. the primary side of a set-up transformer. Then he greys the temples and eyebrows, "How dare you!" snaps the doc -to face accentuates the jowls and puts slight Jerry's automatic. EXPERIMENTER PUBLISHING CO. paunches beneath the eyes. When he's The Master displays his badge. "Dr. 2M1 Fifth Ave., New York, N. Y. through, The Master looks like a seasoned Tolman, you arc a deliberate crook !" Gentlemen: he I wish to take advantage of the special subserip` globe-trotter of forty-five, and you can't states. "Frolic the first I knew that no Lion rate for your important TRADE MAGA- ZINE-RADIO NEWS DEALERS PERSONAL tell the makeup even right next to him. radio wave could produce the shock I re- EDITION. Enclosed find $1.50 for year's sub- "How about getting this stuff off, later ?" ceived, yet this test belt was quite scription, beginning with the latest issue. un- asks Jerry. connected. Now I understand -the belt is Name "It'll wear away in a month or so," the secondary -you made your patients be- smilesDanny, "but don't try to get rid of lieve that they would get shocks elsewhere Address it yourself. When you're through, come by giving them one here. Very, very back here, and I'll remove the signs of clever !" City State age." "It's a lie!" shouts the doc. "I can We goes back to Brightmere, and if I prove that -" hadn't vouched for him Jerry'd never have "Yes ?" drawls Jerry. "Will you take

www.americanradiohistory.com Radio News for July, 1928 69

this test chair out to my home and give me a shock there ?" This goals Tolman, and he flops onto 1 the examining chair. "You win," he mut- ters, as two Central Office dicks come in and give him and the nurse -his wife -a ride in the black bus. Idly, Jerry attempts to remove the make- up. "Oh," he says, coming out of his trance, "it won't come off. I'll have to see Danny." "Which reminds me," I points out, "that McKee was raided last night, and is in the bastille. You'll have to let it wear off." "Not while Danny's alive!" yelps The Master, rushing downstairs to the jail. 1 laughs, and sits there, fiddling with the belt. Someone comes in. I looks up. It's Elaine, with Millicent tagging for company. I finally convinces Elaine about things, but Millie's in the dark. She points to the belt. "What's that ?" she asks. I heaves a sigh. "That," I states, "is my little stray ohm in the vest" INSTALLED FINIS Ground Out Static IN A FEW (Copyright, 1928, by Robert Francis Smith) MINUTES

A. C. Tubes Require Special cwith,StIB-AERIAL Wiring Care Let Ground Waves Bring You Amazing Distance, (Continued from page 39) Crystal Clear Tone Quality, and Greater Volume and even the 210 -type tubes, ordinary flexi- and Selectivity without Distortion. We hook-up wire is sufficient to carry the QUB- AERIAL has brought a new epoch in Radio. No need longer currents in the filament circuit. b.) to bother with troublesome overhead Aerials. Why risk breaking In the average five -tube electric receiver, your neck to put up roof aerials only to have the first storm blow using three 226 -type tubes as radio -fre- them down? Forget your Aerial troubles. Why not use the whole quency amplifiers, and in the first audio earth as a static and noise filter with Sub -Aerial? stage, a 227 -type as a detector and a 171 - COSTS NO MORE THAN AN OVERHEAD OR LOOP AERIAL or 210 -type in the last stage, the three 226 - and less than many. Hook your set on to the newly discovered type tubes draw over 3 amperes; while the Ground Waves that bring practically static -free reception. Don't 227 -type tube takes 1.75 amperes. If a 227 - stand for the squawks and tin -pan reception you get from Air Waves type tube is used also in the first audio when you can step right out and leave that stuff. stage, the current drawn by the two R.F. If you don't believe us, try it yourself. If you do not find we're tubes will be over two amperes, while that right- absolutely right -you don't pay us a cent for the test. drawn by the two 227-type tubes will be We know so well the surprising results 3.5 amperes. The No. 20 wire used in most you'll get that we'll let you put in a o, .p ,oe0 TRY IT FREE! Sub -Aerial entirely at our Risk. hook-up and battery cables is not large L. °4ta enough for use under these conditions. In Don't take down your overhead Aerial. Pick a summer night when static and noise interference on your old ,0es; addition to this, appreciable resistance in Aerial are If ell °4` the wiring may unbalance the filament cir- Itself to YousRight Then on Performance-youe '0 cuits, introducing hum. needn't pay us a cent. Send for "all the Dope 0 s,c e° Rubber- covered twisted pairs, not smaller on Sub -Aerial." You'll be surprised. Do it y.`O 0ItC>rio s`oOF°o`o- than No. 18, should be used. If obtainable, NOW. No. 14, is to be preferred. Aerial Systems , No. 16, or even Underground oc,00" St. Clair Bldg., Dept. 9 -K. I (,, eel., , a Sts ., Cor. St. Clair and Erie 0 0+ ee5' JAS*. 0.aot?*' It e' Vc. Chicago, III. i A' 1 Go9'' Mail Coupon NOW Station NEW! "CHI -RAD" NEW YORK LACAULT'S Recommends - 326 METERS - 920 KILOCYCLES CALIBRA I ED and 2XAL, 30.91 METERS Madison -Moore Super - is owned and operated by the Short Wave Set Nine -in -Line Super Remler 115 KC Super publishers of this magazine THE IDEAL SET FOR THE SUMMER and the Tyrman 70 Our Editors will tallt to you AND SOUTHERN COUNTRIES Complete parts in stock. Dealers several times every weelt- WRITE FOR DETAILS AND and set builders write for discounts. FREE HANDBOOK NEW SHORT -WAVE COILS See your is(ewspaper For Complete Information address Specially built by "Chi- Rad." Write for details R. E. L. LABORATORIES for descriptive bulletin and catalog. TUNE IN ON Suite 405 Dealers and set builders please use 1931 Broadway New York business letterhead when writing for WRNY Headquarters for discounts. STROBODYNE Chicago Radio Apparatus Co and the latest 415 S. Dearborn St., Dept. RN, Chicago R. E. 9 Quick Shipment -AU Parts

www.americanradiohistory.com 70 Radio News for July, 1928 to Suit the ,,: ,.f,r Radio Programs ,,. `` `' ` ', Thermometer (Continued from page 1 î )

Discussing plans of WEAF and WJZ for CONTAGIOUS COOLTH months, G. W. Johnstone, di- the coming is IIFftIIJ(TICN rector of public relations of the National In fact, the general idea right now Broadcasting Company, remarked: "If our to frigidize the music and freeze the ether July and August programs don't sound like atmosphere so realistically that a receiver relayed entertainment from Itbrador, we'll next month will make a sun -filled porch disappointed." seem like Greenland and the living room be mountain re- With the air in the studios artificially reminiscent of piney, breezy who won't welcome such an reduced to a temperature conducive to treats. And pleasant thoughts of far -north climes, every- effort? thing will be cooled, except the announcers' With broadcasters so seriously bent on voices; and they'll hold a genial warmth, service and radio manufacturers offering guaranteed not to hurt on the hottest after- modern equipment to offset the static buga- noon. boo, a successful summer at the loud speaker is assured. LIGHT PROGRAMS An indication that commercial warm - All heavy stuff is being eliminated from weather broadcasting has lost its hazards the schedules. Wagner as interpreted by is emphasized by the intention of most of heavy baritones and mellow contraltos may the "toll- time" accounts to hold their regu- be beautiful in November, but it is not so lar places on the air. They, too, must ad- good in July. And so whatever operatic just their medium to the season and their aspirations are given voice, from now un- plans are in keeping with the general sched- til the arrival of fall, will be the lighter ules of the stations on which they are heard. in which high C's and pale moons will type The fundamental idea in broadcasting ar- predominate. rangements for humid days and warm eve- draina is off the air boards for the Tense nings is to alleviate the discomfort of those next twelve weeks and in its place, wher- in the heated areas. Not only from an en- ever the theater slakes contributions, will tertaining angle but with an instructive, romance and scin- be bright comedy, young helpful aim, every hour will carry some use- themes. tillating ful or amusing message. In the daytime as up as ever Dance music will be pepped programs, domestic- science experts will tell of hot notes of heavy brass but, instead housewives how to prepare summer meals predominating, the tintinnabulations of sil- and how to protect themselves and their ver notes will till summer nights with pleas- children as much as possible from the wann As you like it ant sounds. weather. Alfred J. McCosker, director of station WOR, promises that his programs will be Experts in health will give their valuable BUILD YOUR OWN so in keeping with the concerted effort to advice and the entertainers will do their offset the weather bureau's daily bad -news best to keep a million eyes off the weather LOUD SPEAKER bulletins that the station's chimes will sound indicators, even if it's too hot to do any- "How to Build MODERN LOUD like Eskimo bells to the listeners. thing but listen. SPEAKERS," by Clyde J. Fitch. is a complete For those who are more fortunate and history of Radio acoustics. Every phase of Mrs. Isabelle Turner, who is responsible Loud Speaker design and construction is fully for many of the bright spots on WRNY's can rush away from crowded places to the and accurately explained. The many and the radio will be an added boon. various methods of attaining true tone repro- programs, has her eye on the calendar in resorts, duction are treated in a clear and concise man - planning the coming days, so that what But, from already maturing plans, a re- ner. All types of Loud Speakers, the Exponen- summer will go a long way tial Horn. the Cone. the New Electric Speakers. emanates from the studios at the Roose- ceiving set this Roll Type Speakers. in fact. every method that velt Hotel will be as welcome to her listen- toward overcoming some of the disadvan- has been used to produce clear. audible signals brings flies, mosqui- is most thoroughly covered. ers on July afternoons as a cooling pitcher tages of a season that toes and considerable hot air. The good and bad points of each development of iced lemonade. are honestly and unbiasedly treated. This is unquestionably one of the roost comprehensive treatises on the subject ever written. BUILD YOUR OWN LOUD SPEAKER What Is the Life of a Fixed Condenser? This valuable book contains full construc- tional data and diagrams for the building (Continued frown page 32) of the Loud Speaker best fitted to give you maximum satisfaction with the particular course of production, filter con- receiving circuit that you employ. HOW LONG CAN IT LAST? In the densers are tested to detect defective units. The aim of manufacturers of high- quality 52 pages -fully illustrated-6' x 9' In some cases, condenser sections are paper filter condensers is usually a mini- "flash- tested" at about five times the rated life of 10,000 hours; or about ten years mum working- voltage, and again "flash-tested" of normal radio service in the home. In two tei three times the rated working - 25c actual tests, however, condensers have often at voltage when assembled in blocks. How- THE COPY indicated a life of from 30,000 to 60,000 ever, flash tests are only a check on di- hours; which may well be considered radio ON ALL NEWSSTANDS electric strength and as a safeguard against OR WRITE DIRECT infinity in view of the rapid changes in defective units; they give no assurance of the radio art, rendering any equipment life of a condenser in actual THE CONSRAD CO., INC. obsolete within a few years at most. the probable use. 230 Fifth Ave. New York, N. Y. The question is often asked, "What is the precise nature of the breakdown in CONSRAD COMPANY, INC. HIGH VOLTAGES ARE DEADLY 230 Fifth Ave., New York, N. Y. filter condensers." Well, a condenser in- Gentlemen: Enclosed find 25e. Kindly send m. a copy of HOW TO BUILD MODERN LOUD variably breaks down at the weakest point. The matter of condenser life is one which SPEAKERS In fact, testing serves to check up on de- has hardly received sufficient attention from Name sign quite as much as on condenser mak- set builders. When it is borne in mind ing; since the engineer learns the weak that the elaborate electrified receivers and Addrm points of his work from the results of con- radio -power units of to -day can be no bet- denser tests. ter than their filter condensers, and that City State .....

www.americanradiohistory.com Radio News for July, 1928 71

a broken -down condenser means much time wasted in trouble -shooting as well as in costly replacements, the matter assumes due proportions. Furthermore, even at this late date, many engineers and radio set builders fall to appreciate the accelerated wear and tear on condensers brought about by applying voltages in excess of the true working -voltage. Clife With a It will be noted that we mention "true" U working -voltage, which means just what it C TOWNSEND says to the user; whereas "test -voltage," "tested at -," or "voltage rating," may "B" Socket Power little or nothing. However, a 10% mean A.C. -D.C. From This Month's Mail overload has been found to reduce con- Irvington. N. J. by 50 %. Furthermore, if the Any Cycle The Eliminator purchased from you last winter denser life has been in use constantly ever since, and I want voltage is doubled, the condenser life is Delivers up to 100 volts to say It has been perfect in every way and can- on any set. Full tone, not be beat by any other. -Peter Rummel. reduced to one -thirtieth of its expected span. Clarity, Volume, Distance. Camden, Mo. Your Eliminator is giving excellent service. It is While these facts may appear appalling doing all you claim for it and I am pleased in on the one hand, they are advantageous on every way. It is a great pleasure to listen to Logs 380 Stations my radio as long as I wish and not have to worry the other. They permit of "accelerated" about -B" Batteries, and have plenty of voltage ! at all times. -Ellis B. Mosby. life tests, whereby it is possible to deter- From CUBA to CANADA Fleetwood, Penn. mine condenser life quite accurately in but Never in the history of Radio has there been anything About a year and a half ago I bought one of your that gets such sensational results at this astounding low Eliminators, and it has been running very well a fraction of the time which would be re- Price. Just read this letter received April 26th, 1928: Your ever since. -Earl R. Moats. I ownsend does its work, and more besides. I have It working I have tuned in 380 Lachine, Que. quired for a normal life test. There are about six or seven hours every day. Is giving every satisfaction. I Stations all over the country. and Canadian. Cuban. Mexican, Your Eliminator 9,000 hours in a year. Therefore, Kent. And more tone from less than and Haiti Stations -all on a 5 -tube Atwater the set than with ""B" batteries. Thi P es besides, only a 60-foot Antenna. Yes sir. it is a dandy! -town stations. to determine the life of a good condenser, Nobody can beat it." not only to local but to out of (Signed) WM. SCHULTZ, -H. E. Barnes. it would require more than three years of 72 Seventh Ave., N., Tonawanda, N. Y. St. Petersburg. Fla. socket and get I have had very fine reception with your test at normal working voltage to deter- Just plug a Townsend "B" Power into light Eliminator and never experienced any hum. mine a 30,000 -hour life. Instead, the "ac- your share of these rado thrills. -Russell Lindley. life test applies double the Hewlett, N. Y. celerated" $1.00 The Eliminator purchased from you last fall has voltage; so that the actual number of hours SEND ONLY given perfect satisfaction, in tact, it has operated Simply fill out coupon and slip it Into an envelope with only tar better than some other power units casting obtained may be reduced to a thousand 51.00 and mail at once. Your Townsend "B' Socket Power tour times its price. -A. W. Lee. Unit will be sent promptly. Deposit only 35.85 plus postage hours in this case, or approximately 42 with the postman. Try out 10 days-then if not more than days. pleased return It, and purchase price will be refunded. Incidentally, it may be remarked that TOWNSEND there is a difference between direct- current and alternating voltages. An alternating - LABORATORIES current voltage which is nominally only 110 713 Townsend Street volts rises to a value of more than 110 Dept. 25 volts-as high as 155 volts-twice in every CHICAGO, ILL. cycle, first one way and then the other. So, Money Back Guarantee also, the action of the alternating current on the dielectric is one of swinging its Approved and passed by the rigid particles, first one way and then the other, laboratory tests of Popular say 120 times a second. For that reason, Radio and Radio News an alternating voltage of a certain rating puts much more strain on electrical appa- ratus than would that of a battery, say, which is rated at the same figure. It will Attach Only $1.00 to this be noted that the breakdown voltage of Coupon a condenser should be given as an A.C. i1F -am ------Oam -1 . -- rating; and that it should be as high above TOWNSEND LABORATORIES 713 Townsend St., Dept. 25 Chicago, Ill. the actual voltage to which the instrument Gentlemen: Attached find $1.00. Kindly will be exposed as may be economically send at once Townsend "B" Socket Power Unit, C.O.D. for $5.85, plus postage, on possible. guaranteed 10.day free trial. Name IT'S A LOCAL 10Days I Address FREE Send for I City State TRIAL Lltera.lure ji00K-UP BOOK FREE SCOTT WORLD'S RECORD Build the 9,400-mile Improve you[ reception with receiver. Listen in on all the world. Easy SUPER 10 CARBORUNDUM and economical to con- Stabilizing Detector Units, struct. Results guaranteed. Write today for free circuit diagram, parts list and copies of long Grid Leaks and Resistors distance retention verifications. THE CARBORUNDUM COMPANY SCOTT TRANSFORMER COMPANY Dart. D -1, NIAGARA FALLS, N.Y. 7620 Eastlake Terrace Dept. H Chicago

Dependable The ELECTRIC Radio UTER Radio Freshman Products The Complete Quality Popular Priced Line - EQUAPHASE Send for Comprehensive Catalog LESLIE F. MUTER CO. 76th and Greenwood Dent. 827K Chicago at All Authorized Dealers

As one cf the oldest patent Quality Apparatus firms in America we give In- Our latest bulletin \o. 929 describing our corn. PATENTS ventors at lowest consistent piste line of quality apparatus is yours for the charge, a servire noted fol asking. Write for results, evidenced by many well known Patents of extra it today. ordinary value. Book. Patent-Sense. free. GENERAL RADIO CO. Lacey & Lacey. 631 F St.. Washington. D. C. Estab. 1869 30 State St., Cambridge, Mass.

www.americanradiohistory.com 72 Radio News for July, 1928 How Many Stations on One Your Set Can Now Get Wavelength? Short Waves Sent anywhere In the U. S. post paid upon receipt of (Continued from page 16) price. Canada and Foreign, Make Any SetA.0 60e additional. Money or- der only. Also sent C. O. D. plus postage in INCREASED RECEPTION STRENGTH U. S. if 51.00 accompanies 'with a T C -A order to insure carrying charges. In ordering be A great increase in volume would, it is Sure to name set and tubes very likely, be noted, due to the added used, such as UV199, Filament U X199. WD11, 201A, UX226 signal received from a number of stations. or U Y227. Price $15.00 or $17.50 for A. The sensitivity of the receiver could there- C. Sets. Transformer fore be decreased, resulting in clearer re- The SUBMARINER will convert your regular set Into a short-wave receiver by simply ception and more freedom from static dis- inserting a plug in place of one of the tubes. This takes but a few seconds. With "Submariner" it will enable you to tune between turbances. 26 and 68 meters. This device operates with all sets such as T.R.F., Neutrodyne, There would be no necessity for having Super- Heterodyne and others A C or D C operated. No addi- tional tubes, batteries, or coils required. If set operates a more than one local station broadcast a cer- speaker it will do so with 'Submariner" attached. Operates a wave changer with Super- Heterodyne and as detector unit tain program, as sometimes clone now. with others. It would not be necessary to limit the SHORT -WAVE RECEPTION number of stations on a given chain; the is practical, and especially In summer, as they penetrate better and there is less static. The "Submariner" waveband includes more the better. If the closely -populated practically, All Powerful Stations Which Broadcast Pro- grams. %ou may also listen to amateurs from all parts of the portion of the country could be provided world who transmit code messages. You will have one of the most efficient short -wave receivers when the "Submariner" Is with a 500 -watt station every fifty miles for attached to your set. Get a -Submariner" so you may have each reception of command of the short -wave activities as well as the broadcast chain program, perfect band. If your Dealer does not carry Used with any of the standard that program could be obtained by every- Specifications Harnesses - E_by, Na- a1d, -Car- ORDER TODAY DIRECT ter, etc. -this T. C. A. Trans- one at all times, regardless of reception This device has been nationally advertised, and sold in all parts of MODEL 688 former converts any D. C. Set the world for the past two years PRICE $4.50 into an ultra modern A. C. Re- conditions. easy -inex- J -M -P MANUFACTURING CO., INC. 35 8' x 2 j8 x 3"; ceiver. Simple- Better reception conditions would increase Department S3 Milwaukee, Wis., U. S. A. Shipping Weight pensive. the enhance the value of 53.4 lbs. Finished T. C. A. Model 688 handles audience served, in Dull Black all sets using six tubes or less. programs broadcast, and benefit the broad- Lacquer. Fur- Like all T. C. A. Transformers niched complete this model is especially designed caster and the advertiser as well as the with cord and plug. for its particular use. and scien- listener. Detailed instruc- tifically manufactured to exact tions and layout specifications. Every coil is heat A "distant- reception night" could be held diagram packed in treated and vacuum impreg- as a novelty: at a certain time after ap- each carton. nated with a special compound. This process prevents moisture propriate announcements, all stations but Leading Dealers disintegration and short circuit - one would cease broadcasting, and listeners Carry T. C. A. ing. It means long life and de- still trans- Filament Trans- pendable operation. Clean cut at great distance from the one ApO INVENrIois formers. Ask to laminations prevent internal mitting would attempt to hear it. As it see one! ,;t;. noises or vibrations and ensure elk silent. hum-proof operation. would not be necessary to change the tuning WANTED The world needs radio inventions. One idea may make You rich. a giving the latest complete informa- to ac- We have prepared booklet controls, it should be an easy matter A new book by Raymond F. Yates contains a list of 99 needed tion on A.C. Conversion and Filament Transformers. Your complish distant reception. One by one, Radio Inventions. Don t spend time and effort on worthless In- copy is ready to be sent to you as soon as you write us for it. ventions. Concentrate on the NEEDED inventions described Just fill out the coupon below -and mail it. each station on the chain would in turn in this book. 901 Other Needed Inventions are also de- scribed. Over 100 pages, durably bound. Cut out this adver- take up the broadcasting, giving everyone tisement and send it to us with yottrname ands dress plainly THE TRANSFORMER CORPORATION - written. When the book arrives pay the postman only 51.25 a chance to easily find out the distance pplus e. Money back after 10 day? examination if desired. his set. Many Limitation. writeNOW. (Outside U S.$1.45cashwith order.) OF AMERICA getting qualities of receiving Bureau of inventive Science, Dept. 337, Rochester, N. Y. of this scheme will immediately 1428 -1432 ORLEANS ST. CHICAGO, ILL. adaptations suggest themselves, such as providing prizes Manufacturers of the T.C.A. Line of Power Transformers. Audio Transformers. Chokes, Power Packs. and Power Amplifier Packs. for the one who could verify reception of the largest number of stations, etc. From Chicago's Oldest The fact that two neighboring stations Radio Jobbers. The most valu- have already accomplished the feat of broad- able Radio Catalog. Write for your 6iil1ff` I i14 casting the same program on one frequency copy today-/T'S FREE! TRANSFORMER CORP. OF AMERICA indicates that the day may soon come when TELEPHONE MAINTENANCE CO. 1428 -1432 Orleans St., Chicago, III. 1 chain will be broadcast on the 123 -5 S. WellsSt., Dept.84 Chicago, Ill. IPlease send me your Free Booklet on A. C. all programs Conversion and Filament Transformers. No same frequency. Many look forward to this obligation. , I with great eagerness. VICTOREEN II Name . Super Coils I Send for Folder and our Blue Print I Address I of the new A. C. circuit. ICity State RADIO TERM ILLUSTRATED Geo. W. Walker Co. 2825 Chester Avenue IN WM f- lllil -- -_ Dept. B Cleveland, Ohio 6 -TUBE RADIO COMPLETE 534.75 te $66.66 Licensed R.C.A. Circuits. Shielded. One Dial Write for catalog. Big discounts to agents OI ConsumeraRadloCo., Dep.147,4721LIncolnAv.0h icage O die' If meat amarids, 3 b.ig.relable' A from arena 11.. star 8th ucceatter This handy book should sear. Electric or Better' sets. Cue u or table cabinets. Don't buy un to days go with every Radio! pie. at 2 ioto times the rica selectivity.lbodral distance, volume It is concerned with radio and riebnab Ce s tone. Corn dial forcar II stations. Completely case parts-their functions - bled fully guaranteedus sets! where they are - and testimony their names. It gives the Freeindralnred BIG ATION symbols radio MIDWEST CORfCORPORATIONORATION used In Pioneer Builders Sets hook-ups, so that you 4g4 D MiracoBldginonnati3O. will be able to read any diagram and understand it. It discusses air waves -the aerial-then takes you through every radio Dart-and finally the actual reproduction of DEALERS-SET sound. BUILDERS-ANTS This Is a book that Nef Cf e`O will give you a full under- Write for this Catalog. New standing of your set. Summer and Fall Book. Save money r hookups, sets, kits, parts, ALL ABOUT RADIO PARTS RAO`O on newest arressories at lowest prices. 544 x '71.4 Inches, fully illustrated The "Bit, Friendly Radio House" Get 11 from ano news( Mel nr dtrerl WESTERN RADIO MANUFACTURING CO. THE CONSRAD COMPANY, INC. 126 West Lake street, Dept. 17, Chittien. Illinois "A Choke Coil" 230 Fifth Avenue New York City

www.americanradiohistory.com Radio News for July, 1928 73

Radio Aids Marine GREAT LOSS OF Fire Fighters LIFE FEARED AT (Covtinved from page 13) MONTPELIER heights were rsaehad today in t {,,G . During the second day of the field - the ever mounting toa of 11. P+ r 1+1.1t ¡f4).G _/ wor t J and property los t ths C dem- e. th t tests there tuas an unexpected : strength has sapan d 9 .ttw Entlad .' ' in case ma aio d al thah 4, onstration of the value of this plan öm an.ry.oa j " ' -. ,a ,r OW In 4 M ? . The fireboat was proceeding .. of emergency. mu "a o5twctv in ..,. r slowly up the Hudson River, keeping M°. .r...-.,.. constant touch with the shore station, when atL:.. '°;F `r+...... ,... on the Brooklyn shore was word of a fire .- .. I.rN The tests were at .. -,.,« .:::;.. received at WNYC. once interrupted and word was flashed to . /7 to proceed directly to the scene ..- . 7 the Mitchell -y 4-,--ov ,.,1 of the fire, and report just how serious it was. In re.:ord time the Mitchell arrived on a % aucr ac! the scene and was able to report back that ------the fire was well under control and that no .,- assistance would be required. t./ `' uc .. additional iC au q/, e / Following the field- strength tests, the two r/.jc,Cl..-,+v acv cr.nw..((íyy transmitter.- were changed slightly, and - equipped for radio- telephone communica- à T0 /99 .Cf.- tion for the purpose of a public demonstra- tion. 'l'he captain of the boat was then ordered to proceed out into the harbor and ELECTRIC SPECIALTY COMPANY city officials, stationed ashore at one of the MARK fire boxes equipped with a microphone, is- TRADE "ESCO" to the craft by means of the Conn. sued orders 211 South Street Stamford, radio transmitter. For this purpose the for DX means maximum miles per watt, and that is what ESCO" generators are built microphone was connected to the control Real room of the shore radio station by means of special telephone lines. Plans are now being made for additional tests which, if successful (as there is every reason to believe they will be) are expected 90 Volt Power to lead to the installation of suitable radio equipment aboard all fireboats operated by New York City. Unit :: $12.75

Obtaining Current Supply

for an Electrodynamic AMPERITE is the only automatic filament control that keeps the temperature or Speaker voltage of the tube filament constant de- who spite variations in the "A^ Battery voltage. MANY owners of electric receivers, It guarantees improved tube performance have purchased new electrodynamic and increased tube life through always operating tubes at their proper filament loud speakers in an effort to obtain the ut- temperature. Simplifies wiring, panel de- most in radio reproduction, have found sign, tube control, tuning. Eliminates hand rheostats Do not confuse with fined fila- themselves confronted with a very perplex- ment resistors which attempt to imitate ing problem. Unlike others, an electro- Hums, line noises, etc.; positively impossible with AMPERITE but are entirely different in source of this new advanced unit. Plug in and forget. Non- principle and operation. Insist upon dynamic unit requires an external acid and noiseless. All detector and intermediate AMPERITE. Price 81.10 mounted (in U. direct current to excite its special field voltages plainly marked. Simpler to hook up than S. A.) For sale by all dealers. cells. Operates any type set 1 to 12 tubes. and the speakers will not operate dry thoroughly Write for FREE "Amperite Book" of season's winding, Greater volume and refund. best circuits and latest construction data. The amount satisfied re urn 30 daysfor complete unless this power is supplied. Guaranteed further 2 years. For 110 -120 volts A.C. 25 to Address Dept. R N -7 of current consumed by the field coil varies 00 cycle current. 90 volts, 512.75; 112iá, $15.25: 135. $17.50; 15755, 319.50; 180. 524.00; 202á4a, 526.00. but most units need Also built for D. C. current 110 and 32 volts at only $3.00 ,. diatt CJompany- in different speakers, stocks -same day ship- 6 additional, any size above. Ample approximately 1/2- ampere D.C. at volts. ments. Simply say -ship C.O.D. or write for my Intereet- So FRANKLIN ST.. NEW YORK However, this potential is not available in ng literature, testimonials. etc. circuits where the tube filaments are heated SMITH with alternating current. B. HAWLEY PERITE Conn., U. S. A Nevertheless, this current may be ob- 334 Washington Ave. Danbury, The "SELF-ADJUSTING "Rhcartat tained very easily from a standard trickle charger; as the current used by the field coil need not be pure D.C., and any recti- will DYNATONE fied A.C. of the proper voltage give ELECTROMAGNETIC NEW SHIELDED satisfactory results. POWER SPEAKER UNIT SUPER -10 AN INGENIOUS METHOD Operates on 5 Screen Grid R, F. Amplifiers to the electrodynamic speak- "A" Battery In addition For Cones, 4 Stage Power A. F. Amplifier ers which operate at low voltages, there are Balsa Wood, Airplane Cloth, Illustrated literature gratis other types which require a potential of 100 etc. Complete Constructional Blue Prints, volts or more at a current of approximately $2.00, postpaid 50 milliamperes. When using a speaker of Sent C. O. D. under 10-dä moneyl NORDEN- HAUCK, INC. this type in connection with an electrified back guarantee. Write for literature. Builders of Highest Class Radio Apparatus to the World receiver the power may often he obtained Unit only 512.50 Unit and 12 -lneh Cone.... 515.00 Marine Bldg., Philadelphia, Pa. by using the field coil of the loud speaker in Unit, Cone, and Baffle $16.50 Cable Address "NORHAUCK" filter -choke coil in the "B "- FANSPEAKER RADIO COMPANY place of the Dey New York, N. Y. power unit. 74 Street

www.americanradiohistory.com Radio News for July, 1928 How the Radio Public is Fooled (Continued from page 29)

the trial order card. You will get the Claim No. 5, which claims that the "Kleer- greatest radio reception you ever heard and Tone" gives your set at least one more the money- making chance of a lifetime. Mail stage, is not at all true, and cannot be L TIRE the card today, sure." substantiated. As to No. 6, the "Kleer-Tonc" does not WHAT IT IS separate low -wave stations any more than After dissecting the "Iaeer- 'lone," we high -wave ones, and does not do so on all found that, as stated before, it is nothing stations. STFCBODYNE but a radio - frequency transformer. 'l'he No. 7, the claim that the device saves primary and secondary are wound on card - from 30 to 40 per cent on batteries, is a hoard tubing 4 inches in diameter and 100% untruth; it does nothing of the kind. 1 -13/16 inches wide; the winding was done The inference here is, no doubt, that on very poorly, and the condenser used is of some stations where the "Kleer- Tone" brings the 1921 vintage, with the cheapest kind of the radio set into resonance, if your set is

material, mounted on an ordinary piece of . such an antiquated device, it will undoubt- wood. Incidentally, the condenser knob edly make it possible to turn down the on the sample works so hard that we won- rheostats. On most modern sets this will der if it is possible to, attempt any tine not be true at all; and it only can hold true tuning. for a few stations, but certainly not for all, The characteristics of the windings are on the old models. as follows: primary, 9 turns of No. 26 D.C.C. wire; secondary, 31 turns of No. 26 D.C.C. SAVE YOUR MONEY 'The wire. The device has an inductance of 157 Yet, this famous (ieppert "Nicer- Tone" Greatest Super microhenries. 'l'he tuned circuit of the sec- sells for $4, when devices as good or better ondary and condenser covers no more than can be bought for as low as $1. If this Heterodyne approximately 400 meters. were advertised as an ordinary wavetrap, 'Phis, then, is the well- known, old -time and it was honestly set forth that the device and time -worn device, commonly known as is useful to separate some stations and help the ordinary or garden variety of wavetrap. to make your set tune sharper, no one would and revolutionary principle is em- lind fault with it; but the rest of the claims ANEW WHAT IT ISN'T bodied in the Strobodyne. This new are simply plain bunk, and some deliberate principle is based on what is known as the The statement that the device eliminates "Stroboscopic Phenomenon." untruths. The device, however, has one great It is the appli- 50 to 90 per cent is, cation of this phenomenon to the basic prin- of static of course, un- redeeming feature, and this is the only good ciples of Super -Heterodyne construction that true. This device no more eliminates static one that we could find. The bottom is has placed the STROBODYNE so far ahead than a pair of suspenders would. covered by a piece of felt, so that it will of all other Super -Heterodynes. The STRO- The second claim is partially true, that not scratch your radio. BODYNE employs eight tubes and is a with some stations there may be a slight It is such claims as we reprint above marvel from the standpoint of selectivity, increase of volume; but this does not hold that make the public weary of everything in accurate tone DX reproduction and as a set. true of all stations. radio today, and, the sooner ;orne manu- The third claim, that the device brings in facturers learn this lesson, the CONSRAD, better it Of course the oldest and original more distant stations, is only partly true. will be for them. They have, radio pattern publishers, were given the task of course, the It does not do so on all wavelengths, of publishing complete instructions for the but right to take a certain amount of poetic building of an efficient STROBODYNE only on some. license in some of their advertising copy; RECEIVER. In designing the best and most Claim No 4 is perhaps the most truthful; but the thing becomes vicious when too comprehensive instruction material, they have in that the device actually will tune out many liberties are taken and when deliber- excelled. The STROBODYNE PATTERN powerful local stations, but, again, not all ate statements, that can ncvrr i.e sub- BY CONSRAD contains four full size blue- of them. stantiated, are made. prints and a special 16 -page instruction book- let that answers fully every question on STROBODYNE construction.

Write today -Cet a full set of STROBODYNE patterns from CONSRAD- You will be Experiments With a Double - Ground more than satisfied with the results that a STROBODYNE RECEIVER assures you. System Full constructional data By W. H. Griffith, M.D. only 50c SOME time ago the writer accidently This arrangement gave much louder signals discovered that, if the far end of an than were being obtained with an ordinary ordinary single -wire aerial is aerial about 100 feet long. THE CONSRAD CO., Inc. grounded instead of being insulated 'l'hen, with the idea that the new aerial from the ground, 230 FIFTH AVE., NEW YORK, N. Y. the signals may be ac- night be too long, a .0005 -mf. fixed con- tually increased in strength. They are not denser was put in series; and this seemed diminished or destroyed, as one might ex- to be an improvement. The next step was pect. Since then two or three references to to replace the fixed condenser with a .0005 - THE CONSRAD CO., INC., this fact have 230 Fifth Ave., New York, N. Y. been seen in radio publica- mf. variable, to determine what capacity tions. was best to use. It was found that there Gentlemen: Kindly send me a hill set of blueprints and all data required for building the emclent STRo- A single -wire aerial was constructed; 140 was an optimum setting for each wavelength BODYNE RECEIVER. Enclosed lind 50e. to cover. feet long, 20 feet high, at the end near the in the broadcast band, although it was not set and 15 feet high at the far end. The far critical. The operator in reality Name was tutting end was grounded by leading a wire down a big loop (Fig. 1). to a piece Address of gas pipe driven 6 feet into the ground. The near end was attached to the ONE BIG COIL city ..State "aerial" binding post of the set; and a wire As the next logical step, the writer tried from the "ground" binding post was at- connecting the aerial direct to the grid of tached to a water pipe in the basement. I!Il!IIllhIIMlIlIDhP 11111111V I! II 1111111111!! 111V IV V IV V I V 11111V IV 1111V the first tube, and the ground (in the base-

www.americanradiohistory.com Radio News for July, 1928 75 ment) to the filament; and shunting the than average efficiency, receives almost variable condenser between the aerial and everything in the country when using the ground. This was actually tuning the loop new aerial, reception being limited by the No v.s a loop is usually tuned (Fig. 2). The noise level and congestion of stations. directional effect is noted. Daylight re- ception from WCCO, WHO and WOW is especially good. These stations come in every day with volume sufficient for an auditorium. It is an interesting fact that the above stations, which are about 300 miles away, come in with almost the same intensity day and night; while Chicago sta-

FIG. 1 tions about 600 miles distant are heard very poorly during the day. So far as the writer knows, this particular type of antenna hook -up is something new. In "Radio Engineering Principles" by Lauer and Brown (McGraw -Hill Book Co. 1920) there is mentioned the type of circuit shown 140 FEET in Fig. 1, and there have been other similar FIG 2 arrangements using two grounds.

EXPERIMENTAL POSSIBILITIES ,e% The circuit of Fig. 2 is quite different, Largesb Exclusive J adii-Elbe however, and a marked difference was found Man facturers in theWorhL in results obtained by the two methods. Whether it is new or not, it is thought to be worth directing attention to. The pres- ent tend seems to be toward greater ampli- The upper picture shows the double-ground fication of weak signals from a loop or Reasons which obviously becomes a true loop, 5 system, is cheaper than if we complete the circuit as in Fig. 2; which short aerial; but aerial wire has been used successfully, as well as the tubes and the cost of maintenance is nil. Why you should Fig. 3. crystal hook -up in 'l'he length of this aerial will limit its use use CeCo Tubes. as it will not he adapted to congested dis- with a larger con- effect was indeed surprising; this loop, made tricts. A shorter aerial results. up of about 180 feet of wire (including lead - denser might give good Because 140 feet of earth, tuned almost Another disadvantage is that it intro- ins) and can as the ordinary indoor loop. duces an extra control; but the controls the exclusive process as sharply the other Previously -weak stations now came in with be kept clown to two by ganging of evacuation results was actually im- condensers of the set. good volume, selectivity ar- sensitive, and the ratio of signal to static A number of possible uses for the in a more proved, but the seemed better than with the ordinary aerial. rangement have been suggested, clearer and longer used covered the entire band writer has macle no effort to investigate The condenser how life tube. nicely. them. One of them is the question, a transmitting As a critical test, a crystal set was as- well it would function as using the antenna as described, antenna? He does know that his set can be sembled; forced. He the variable condenser, crystal and phones macle to radiate, if deliberately Because to use this aerial as in Fig. 3. Two Chicago stations, WBBM would not advise anyone he wants to make any radio and WON, and also KMOX, St. Louis, with a set that radiates unless they were heard in one evening (January 23, have the neighbors on his neck. set perform better. adaptability of 1928) and WON was heard two other nights Another question is the -wave reception. the same week. Each of these stations is the system for use in short the proper size of aerial about 600 miles from the writer's residence The working out of Because Huron, South Dakota. and condenser for various bands should at for any- The writer's present set, which is a seven - provide considerable amusement 14 inspection tests so inclined. tube tuned -radio -frequency affair of less one assure absolute uni- formity. Radio Terms Illustrated Because the leading radio ex- perts use and endorse them. Because you can secure "spe- cial purpose" tubes from CeCo not ob- tainable elsewhere. To Dealers: When attending the Chicago Radio Show, cat! on us at Booth 107. CElS4¢GCO-Inc Vsr.! EMK.I 1,34W. P1R,OlrifüENClE lftá- "A. Howl Arrester" "Broadcasting on the Chain"

www.americanradiohistory.com Radio News for July, 1928 dadssmors Vacuum Cameras to Speed Up S.Gertsback's Television (Conan nett from pale 23) RADIO AMPLITUDE MODULATION utilized in the camera and projector shown To look at it from another angle, we have here. The cathode he knew was a dished ENCYCLOPEDIA an oscillator with a 500,000-cycle frequency. plate, as in an X -ray tube, and the poten- We couple to that a microphone by some tial he indicated for causing a discharge be- magnetic or electrostatic method, and in- tween cathode and anode was 60,000 volts. troduce the 1,000 -cycle note. What hap- Some three or four years ago T. Thorne pens? The oscillator's output- frequency Baker took up the system in an attempt changes; we create a sort of heterodyne. to adapt it to radio transmission, in the Suppose, instead of that, we could maintain manner above mentioned, but utilized the our oscillator frequency constant (by means electron discharge from a filament. He of crystal control, if necessary) with a re- retained the photoelectric cubes and the sistance in the oscillator circuit, and find baffle plate already mentioned. Neither the some way to increase or decrease this re- Swinton nor the Baker device has ever been sistance on all except 1,000 of the made operative, and we need not go further oscillations. into their theory to see why. Neither in- Nobody knows yet how to do this, but ventor suggested a camera device, and that it may be solved by some photoelectric de- shown here is, I think, the first suggestion vice. Perhaps we could include a film of of a portable, self- contained apparatus, selenium in the oscillator circuit and have without moving parts, adapted for any type Over 25,000 copies on the microphone diaphragm a mirror re- of camera work on either still or moving in the still binding flecting light to the selenium cell, thus objects. If for no other reason, the design already sold modulating the power output, the amplitude should be of interest as being the first and of the waves, instead of their frequency. only suggestion in the history of the art for Until something of this kind is done, tele- transforming light into electrical impulses o /ín limp vision must go to the short waves, unless without the use of a photoelectric cell of ; it limits itself to simple, small pictures of the conventional type. a few dots per square inch. The other an- sgcdc Ieat4er swer is a special dispensation from the THE CLARKSON CAMERA Radio Commission, such as was given to The thcóry. is simple. Certain vapors and WGY to make possible the demonstration of certain liquids, too, are more conductive bidÉjq, combined wire- and -radio television in Schen- in light than in darkness. One of these ectady some months ago. fluids is sodium vapor, familiar to all by having been used in the Donle tube. In PIONEER WORK the vapor chamber of the television cam- is It apparent that the three great prob- era (Fig. 1) we may have sodium vapor, lems IN KERATOL can be solved. The solution to two and the temperature of the chamber may BINDING of them, I firstly believe, lies in the prin- be regulated by the heating coil H. The ciples of the television "camera" and pro- . wall G of the tube is of transparent ma- 2. jector in J illustrated this article. Like every terial, preferably quartz, and an image may The most valuable of Radio Books- S."Gerns- other method known, this is based on work be at will focused on the composite plate back's Encyclopedia done long before -now the most beautiful. broadcasting began. It C, which is simply a number of insulated, This foremost Radio Encyclopedia is now with started suggestions by the eminent conductive wires or cubes. It may be a offered in this luxurious new binding to meet scientist, English A. A. Campbell Swinton. bakelite plate in which are embedded small the demand for a more handsomely bound I have made many material changes in his volume. The limp Suede Leather conductors. Edition thought, as it was not even sells for $5.00. The Keratol- leather stiff theoretically In front of the composite plate is a screen binding still can be had for $2.00. sound when be gave it to the world seven- S of metal wire, which not only divides the Remember -this is an encyclopedia -not a teen years ago. The most notable changes light into rays when an image is projected dictionary! It took over two years of intensive I have made are: (1), in doing away en- on the plate, but acts also as a terminal labor to compile it. It is the first Radio tirely with photoelectric cells in the trans- in contact with the vapor. Encyclopedia ever published. mitter; (2), utilizing a closed electric cir- S. Gernsback's Radio Encyclopedia con- At the other end of the camera tube is cuit which includes as part of the current a concentrated filament, or cathode F and tains the meaning of every word and phrase path, the electron -beam itself. In the used in the Swin- a plate, or anode P, which has a tubular entire Radio Art. Every circuit. ton part and apparatus is thoroughly explained. device, the plate on which the image opening. With proper plate voltage a flood A complete cross index is just one of the many falls was a collection of cubes of rubidium, of electrons shoots from the cathode to the features of this remarkable book. potassium, or other substances which dis- plate; a stream of them passes at high speed There are 1.930 definitions-549 diagrams, charge electrons when light falls on them. through the tubular opening, creating photographs and drawings simple and -all T. Thorne Baker contemplated carrying a narrow beam which impinges on the back easily understood. The book is nearly an those electrons as a charge to the floating inch thick and measures 9 x 12 inches. of the composite plate C. This beams is grid of a transmitter tube. Swinton him- really a flexible, weightless conductor, an S. GERNSBACK self suggested carrying them by wire to electric current without a wire. It has the deflecting plate of a Braun oscillograph 230 Fifth Avenue New York City around it a magnetic field, like any other in the projector. conductor, and any magnetic field of the Neither of these methods is sound; one S. GERNSBACK 7 -RN coil A will attract or repel the field of the 230 Fifth Ave., New York City reason being that the entire plate of photo- electron beam, thus moving the beam itself. Gentlemen: electric cubes would be constantly discharg- Kindly send me one copy of The Radio Encyclopedia. I will pay postman on delivery. ing tinder the influence of light, and par- THE PENCIL OF ELECTRONS with the Limp suede leather binding ticularly shifting images of mov- If we put an alternating current in coil 05.00 plus postage ing objects. This mass discharge, as a A, the weightless beam will move back and Keratol- leather binding background. would overshadow any continu- $2.00 plus postage forth vertically in unison with the coil fre- (check which binding you Wang) ous discharge from the scanning by an quency, as it has no inertia. This coil fre- electron beam; and, without some other quency is, say only 5 cycles per second. Name change, the floating grid might soon be Then the beam will go back and forth Address made so negative as to affect the trans- across plate C five times a second or, in Town mission. other words, will cross plate C ten times Sr.,,' Swinton macle his suggestions in 1911 and per second. knew nothing of the two -element tube In the saute win-, and at the same time,

www.americanradiohistory.com Radio News for July, 1928 77

coil B is moving the beam horizontally, say the beam on the screen becomes visible; the 1,000 times a second, or across the plate light and shade from instant to instant de- C up and down 2,000 times in each second. pending on the intensity of the beam. This LEARN 'l'he distance moved horizontally or ver- instantaneous intensity is proportional to tically depends only on the strength of the the received signal and, therefore, propor- the light and shade RADIO coil field, which may be changed by moving tional to the intensity of the coils towards or away from the tube, of the image points on plate C of the cam- find is point by and . or by changing the current in the coils. era. Thus an image projected, Now, with arrangements of the frequency point and line by line, on the phosphores- Good Pay from the Start, stated, the beam will go up 100 times and cent screen in the projector. Rapid Advancement and down 100 times for each trip across plate This image is readily visible in the partial C. If the distance across the plate is 8 darkness caused by the hood over the screen Phenomenal Success in inches, the beam will, in effect, draw 25 and may be larger or smaller than the A Life Profession of vertical lines on plate C for each inch of original image; one way of changing the Fascinating Brain -work. width. If the conductive portions are size being to move the phosphorescent screen The image may be applied to properly divided and positioned, the beam in or out. At Home ! will hit each one of them once in this jour- a filin running through the vacuum tube You Can Learn ney across the plate. by means well known in the oscillographic Here is your big oppor- art; or it may be projected by prisms from tunity! Our graduates screen upon the wall of are earning big money THE CIRCUIT the luminescent as radio designers, as the room. Suppose the beam strikes a conductive radio executives, in portion of the plate C which happens to SPEED OF THE ELECTRONS broadcasting work, as rays of light skilled service men and be strongly illuminated by the The electron beams may be moved at radio dealers. We have upon the other falling through the screen S speed and have been known to record trained thousands to will any R. L. DUNCAN, side of C. Then some of the electrons frequency as high as 220,000,000 cycles Director. R. I. A. become successful ra- of the light a travel along the ionized path per second. Thus any speed of transmis- dio operators on ships and in shore sta- vapor, from conductive sec- tions. And now opportunity is knocking ray in the that sion is possible. Any sluggishness in the and a current at your door. Are you going to plod along tion of C to the screen S; passage of the current through the vapor the resistor R at a thirty-five dollar a week job when will flow out around through will have no effect on the image; as it will F the fila- REAL MONEY is waiting for you in radio? and back to the cafthode along be uniform sluggishness all over the plate beam itself and the con- ment wires, the C. In fact, selenium may be used for the A the completing the New Course ductive path in plate conductive portions of plate C (though not The screen S may bave a positive After years of experience, the Radio In- circuit. when potassium vapor is used) and thus stitute of America has evolved a new and potential bias to aid this action. variation in the current impulses revolutionary course in radio -right up to this an added The current which flows around path produced by the effect of light and shade the minute and abreast of the most recent by the conductivity of the is determined on plate C, will be obtained. developments in the radio industry. ray between plate vapor path along the light There are many incidental advantages in with the very fundamentals and conductive point. It starts C and screen S at each the apparatus which has been described but, takes you through every phase of radio depend on the intensity - This, in turn, will in one particular, it gives rise to hopes that right through television, photoradio- point. Thus, as of the light ray at that have never been dreamed of before; and grams and airplane radio equipment. sweeps over or "scans" the electron beam that is, of a reproduction comparable to The instruction is the work of radio ex- is a varying current plate C, there created a "half- tone." In no oilier method is this perts, and its clearness and simplicity are on the in- through resistor R depending even conceivable; for the reason that, while such that you can master every point with tensity of the image at different points. gradations of light and shade may be ob- ease. You take examinations - your will cause a vary- papers are corrected and all your ques- This variation in current tained, all of the clots reproduced are of ing potential across resistance R and this tions answered by men with years of radio the same size and shape. With the pro- experience. is the potential applied to grid and filament jector shown in this article, the reproducing tube. 'l'he condenser Cl of the amplifying beam varies in intensity, in number of elec- A -1 Equipment permits the grid circuit of the tube to be con- trons, and thus in size, under proper A large kit of first -quality equipment is adjusted to its best operating point. The ditions. Intense beams will cause large output of the tube may be amplified and included in the cost of the course -with- dots and less intense beams small dots, and out extra charge -parts for making a used to modulate a carrier wave. (See thus a gradation of the pictures may be hundred different radio circuits and the Fig. la for details of the circuit.) expected. Peerless Signagraph and key and buzzer Theoretically, this is the most perfect set for code instruction. THE PROJECTOR television device yet described. It has Then, at the receiver, the amplifier out- every element desired in such an apparatus. R.1. A. backed by RCA, G -E put goes into the projector tube (See Fig. With every other apparatus we can imme- and Westinghouse 2) which operates like any radio vacuum diately see definite limitations even on the Conducted by RCA and enjoying the ad- tube. The grid G is heavily biased nega- theoretical side. With this we cannot. vantages of RCA's associates, General Elec- tively. Thus no electrons escape through Whether its performance justifies its prom- tric and Westinghouse, the Radio Institute the tubular opening in the plate P. When ise, I hope to report to the readers of of America can and does give the finest ra- the varying signal impulses come through, RADIO NEws in the very near future. dio instruction obtainable anywhere. however, this bias is counteracted and ( EDITOR'S NOTE: The theory and con - through the tubular opening passes an elec- struction of the cathode -ray oscillograph Home Study Course tron beam varying in intensity with the was fully described in articles in RADIO Moreover, you can STUDY AT 1926.) HOME -when you please and as long received signal. NEWS for January and February, as you please. Here again we have two coils at right This new booklet describing the angles, having the same frequencies as the course is now ready. If you want to coils of the camera tube and in phase with learn more about the lucrative and Ground Often Unnecessary fascinating profession of radio send those frequencies. When the camera beam is the coupon now for your copy. at the top, the electron beam of the pro- on Electrified Sets jector is at the top. When one is at the left, many radio receivers using "A" RADIO INSTITUTE OF AMERICA the other is at the left also. The relative po- WITHand "B" socket-power units, the usual Dept. A -7, 326 Broadway, New York City sition of the end of the projecting beam on conductive "ground" connection to the the phosphorescent viewing screen of the steam or water pipe can be dispensed with, RADIO INSTITUTE OF AMERICA projector is the same as that of the camera in many cases. It seems that the capacity Dept. A -7 356 Broadway, New York City beam on the plate C in Fig. 1. effect between the primary and secondary Dear Mr. Duncan: Please send me your new catalog. I want to know This viewing screen is phosphorescent and windings of the transformers in the "A" more about your new radio course. is swept or "scanned," just as plate C and "B" devices is sufficient to effectively Name is scanned. When the electron beam "ground" the set through the house mains; strikes Address this phosphorescent screen, it "luminesces" one side of practically all house -lighting or lights up at that point and the path of circuits being thoroughly grounded. City State

www.americanradiohistory.com 78 Radio News for July, 1928

il,r. Itp.tw l'n. :'_:;:; Radio Aerials Create No l::::, i'- ::: .::; `:ÿ':: : Lightning Hazards (Continued frate page 31) JTAILL

reader may be referred to `Harnessing ABOUT Nature's Electricity," by Henry Townsend, in SCIENCE AND INVENTION for June, 1928 - ÈnITOn.) " 1 LABORATORY-MADE LIGHTNING However, the radio engineer, like the Television is becoming more and radio listener, Weill be interested more in more popular every day. Get in the effects of electrical storms than in their on the ground floor. Remember causes. It is known to all that the equali- it was just a few years ago that zation of voltages, which is the function Radio was going through the of the lightning stroke, takes place between sane stages of development that two clouds, as well as between a cloud and Television is today. It is the ex- the 90-Day or2Jy earth. The flashes of lightning between perimenters of the old clouds are to be seen only when there is "fan" Guarantee o p days that are now An absolutely unequaled a difference of voltage between them- reaping the value! We want you to test al) rewards of the "successful" in the the World "A" Socket Power BaJ that is, when the process of condensation Unit and compare it with L+.Q. radio field in any other of two or three has gone on more rapidly in one than in and, Television there times the price. Try for ten the other. is the sane chance for success days at our risk. Then if you are not convinced - that It Is unsurpassed as to quality and wonder- When the lightning strikes the earth, how- the same field price will be refunded to for experimenta- ful results, purchase is full. Operates on S0 or GO cycles at 110 volts ever, it of very practical interest to know tion that Radio afforded. Those A. C. Highest quality Westinghouse electrical how it will conduct itself. equipment. No hum or noise. Approved by Radio This question who come out on top of this News Laboratories and other leading Authorities. may be investigated experimentally on a write infant industry will be the ones Send Order Today yourJust name and small scale, with interesting results. address on a slip of paper -pin a one dollar bill who, realizing its possibilities. to it and mail today. We will ship same day 'l'he writer has in his laboratory high - order is received for $12.75 C. O. D. 5% discount voltage apparatus,- and has built for the grow with it. Television will un- for cash with order. Remember you are the Judge and are fully protected-so send order purpose of his research into lightning the doubtedly attain the proportions, NOW. miniature "village," studded with lightning as an industry, that radio enjoys rods and aerials, which is illustrated here. today. This is your opportunity The pictures accompanying 1241 S. Michigan Avenue this article show -it knocks but once -take ad- Dept.60 Chicago, Illinois the discharges of artificial lightning, under vantage of it. Send for the book {Station W. S. B. C. owned and operated by conditions simulating on a small scale those World Battery Company J Ht "Television" written by accepted occurring in nature. Fig. A is a composite photograph, repre- authorities on the subject. senting the path of many electric discharges, and illustrates the well -known fact that BUILD AN EXPERIMENTAL., lightning does not follow the straight line ARTE which would be its shortest path, but takes TELEVISION SET a zigzag or wavy route which is determined NEW TAPERED by the resistance which it encounters at Build Yourself an experimental RHEOSTAT each instant of its progress. It will be seen Television set. In "TELEVI- that the majority of the discharges did not SION" you will find complete go to the highest point in the little group - information the lightning rod on for the construction the church tower - of but elsewhere in the field. The picture bears an experimental outfit. Every witness also to the truth of the old saying, phase in the construction and de- that a lightning rod protects no further velopment of Television is fully than a radius equal to its height. and comprehensively explained. Resistance wire is wound with grad- In the path of the stroke, the conduc- Mail this coupon today. Don't uated increased spacing on tapered tivity of strip. the air during the instant of dis- wait ! Over 112 pages -fully il- Gives current variation approximating charge is the controlling factor, as we have lustrated -large magazine size. a straight line. Permits even control said above. a particular throughout entire rotation of knob. If pathway in Particularly suited for A. C. circuits. the air has an especially low resistance, the Also potentiometer types. lightning will follow this to the earth. In At All Newsstands Fig. A we see the series of discharges that or Write Direct Radio Co. strike to one side from the lightning rod CarterCHIC AGO and aerials; and Figs. B, C and D illus- trate this point still further. The miniature village and the artificial - THE 501 COPY lightning apparatus is pictured in Fig. E, HOTEL FORT SHELBY and a map of the little village, showing the DETROIT LAFAYETTE and FIRST, location of the lightning rods and aerials, is EXPERIMENTER PUBLISHING CO. 22 stories; 900 rooms; beautifully furnished; every con- venience. Shopping, theatrical, and financial districts given for comparison in Fig. 2. 230 FIFTH AVENUE, NEW YORK, N. Y. practically at the door. Comfortable rooms at $2.50, $3, $4 a day: also larger rooms and suites over - looking city. river, and Canadian shore. Servidor "FORKED" LIGHTNING throughout. Guests' cars delivered without special EXPERIMENTER PUBLISHING CO. service charge. J. E. FRAWLEY, Manager. We have in the background the high - 230 Fifth Ave., New York, N. Y. voltage apparatus and its switchboard; the Gentlemen: tindly send me a copy of highest voltage is produced at the point of "TELEVISION." Enclosed lind SO cents. the wire fastened to the upper end of the large coil which is extended over the table Name at an angle. The miniature houses are Sig New 1928 Catalog - Shows latest A-C Address circuits. newest Ideas. 4000 leader. Get sets and erected in a bed of moist sand, a little more parts you want here. Save money. Parts, kits, complete factory-built sets, supplies. /PA to than two feet below the end of this wire. City State Quick service. Write for free copy. es Sfondard disemmii to dealers. set builders, a The aerials and the lightning rod are aorins. Rarawi't Co.. 129 N. letter- in wet which lies man St., Dept. 807. Chicago. USA. grounded this sand, upon

www.americanradiohistory.com r- Radio News for July, 1928 79

the metal plate which forms the other elec- induced in a receiver if it is still connected trode of the high- voltage apparatus. to the grounded aerial lead. -for In Fig. B is shown a single discharge, in For this reason, it is recommended that which the principal stroke was accompanied the receiver be cut off from the lead -in by several minor ones. It is necessary to at the point where it is grounded, during BETTER RADIO imagine that, in addition to the path of storms; or at least that it be placed sonic the principal discharge, there are a num- distance from this point. ber of others possessing more or less con- The grounding of the aerial recommended ductivity, through which lesser discharges by broadcasters is desirable, less to diminish

A manual of 36 pages and cover -with 88 illus- trations and over 20,000 words of practical, concise, readily understood text -prepared by Austin C. Lescarboura in collaboration with our engineering staff. "The Gateway to Better Radio" tells what's what for bettering your radio receiver, amplifier or power unit! what's what in A -C tubes, short -wave reception, im- proved tone quality, added sensitivity, and so on! and what's what in interpreting radio circuits and innovations for best results. Usable, Un- selfish, Unbiased. Just the plain radio truth, such as you can put to work. All for 25 cents. to defray mechanical coats of publishing! Order your copy of this manual now before it is out of print from your- local radio dealer, or direct from us by remitting 25c in stamps or coin American Mechanical Laboratories, Inc. Specialists in Variable Resistors 285-7 North Sixth Street Brooklyn, N. Y. --- s`ARO Tat.T.TAT &ìl25Wee'C'T Charging Batteries e, Starts You Let me show you how to make big money right from the start. I've prepared a FREE book explaining all details. First week's profit pays for all equip- ment. You can get all the battery charging business in your community with my Service Station Charger -it's years ahead cf or- The high-voltage apparatus with which the miniature village was bombarded. dinary chargers - handles 50% to 70% more batteries. I explain everything -start you in a business of your own and put you on the way to take place. In Fig. C the minor discharges the danger of direct lightning strokes, which big money. Write for FREE BOOK. C. F. HOLMES, Chief Engineer, Dept. R;N are also plainly visible, the heaviest one are rare, but rather to diminish or prevent Independent Electric Works falling on one of the aerials. In many cases the setting up of internal voltages caused by 5116 Ravenswood Ave. Chicago, 11t. it is not the principal flash, but one of the minor strokes, or by inductive effects. minor ones, which has fallen upon an aerial, The production of voltages in this man- FREE BOOK Just Out when its owner reports a stroke of lightning. ner is more likely to occur -and far more If the principal discharge has really fallen so that of voltages induced by a stroke on upon the aerial, it will generally be found electric-light wires than by a hit on the that the wire has been turned into vapor aerial by a direct bolt of heavy lightning. instantly, so that there will be no trace of Where a bolt falls with full force, high To Dealers -New. illustrated 1928 Wholesale Radio Catalog gives lowmt it remaining. voltages are produced for several hundred prices on accessories, kits. packs, parts and sets. Features master -built single control radio A typical case of concentration of the yards about, and all electric conductors are sets for both battery and all -electric operation. entire discharge will be found in Fig. ll, likely to be charged to a Pull showing of "A' and "B" Eliminators and disagreeable extent. thousands of other great values. Write on bust- where a very vivid stroke lias fallen upon To combat the formation of the induced eaa letter -head for this tree book today. HAMILTON -CARR RADIO CORPORATION the lightning rod projecting above the potentials to which reference has been made, 711 West Lake St., Dept. 396, Chicago, Iii. church steeple. it is recommended that indoor aerials be grounded in the case of a storm. If the CONCLUSIONS aerial is so grounded, and the operator The desirability of the use of 1igürting avoids contact with it, there is no additional arrestors, to be installed where an aerial danger from its presence; but, on the con- is led in to a building, is apparent, to avoid trary, through the grounded aerial serving Balkite entrance of the high voltage of the light- as a miniature lightning rod, the energy is ning discharge, in the very rare event that led harmlessly away, which would otherwise the principal stroke should fall upon the be felt in the vicinity of the aerial. Radio aerial. In the case of such a direct stroke, The aerial cannot attract lightning from the drop of voltage across the ground wire any great distance; so that the improba- is accompanied by a FORMICA KIT PANELS current of great in- bility of lightning striking a house thus Drilled and decorated for leading kit sets are available through tensity, but infinitely short duration; but is equipped is very great. This will be seen leading lobbers everywhere. so great that a considerable voltage may be from the composite view in Fig. A. THE FORMICA INSULATION COMPANY tif Spring Grove Avenue, Cincinnati, Ohla

www.americanradiohistory.com 80 Radio News for July, 1928 Radio Behind Prison Walls SAVE YOUR MONEY ! BE YOUR OWN SERVICE MAN (Continued from page 11) THE RADIO TROUBLE lose respect for the law and plan for revenge havior. We learn that opportunities exist THE RADIO FINDER when liberated. on the outside for those of us who would FINDER TO(Iay we have the radio and long for live the right kind of life; and when I say TRWBIE Even the highest - priced radio set liberty, just as much as ever, but we come that radio is making better men of us all, occasionally de- to the cold realization of the fact that I'm only expressing the thought of every velops a fault and liberty can only be gained by good be- other unfortunate devil in here. that at a time when you least expect it-maybe right in the mid- dle of an interest- ing program. But, a handy copy of The Radio Trouble Finder is the sim- ple means for tracing every defect and remedying it in the easiest manner possible. There is no mishap that could befall a radio, but what is fully covered in this valuable book. The Radio Trouble Finder is edited by men fully versed in the subject covered -men with years of actual ex- perience behind them -and who have grown to prominence since the infancy of radio. Don't wait till your set goes bad -get your copy of this remarkable guide to radio trouble now. Fill in the coupon and we will send you by return mail a copy of The Radio Trouble Finder, a money -saving investment. You can be your own service man.

The 25C Copy

BUILD YOUR OWN RADIO SET 150 RADIO HOOK -UPS This is the latest issue of this re- markable book. Absolutely new and up - to - date. All the best cir- cuits of the day. { Full instructions on how to build. Make your own set from the dia- grams shown in 150 Radio Hook - { Ups. Write today -pick the set you want to build and make it. Then you are sure to be satisfied with the results you get. 150 Radio Hook -Ups was prepared by The central radio receiver of the New York the staff of Radio State Prison at Ossining (`Sing News. An accurate Sing ") with its power guide to better set construction for the amplifier and distributing system, which actuates also a radio "fans." public- address system.

The 25c Copy Obtaining Detector Voltage from a Home -Made Power Unit MAIL THIS COUPON NOW WHEN constructing `B" socket -power plate voltage in the power pack. By this CONSRAD CO., INC. units, many experimenters plan to system an additional resistance -filter stage 230 FIFTH AVENUE NEW YORK. N. Y obtain plate voltage for the operation of is provided, which greatly improves the the detector tube by tapping voltage - CONSRAD COMPANY, INC. the current delivered to the plate circuit of 230 Fifth Avenue, New York. N. Y. dividing resistor at the proper point. It the detector tube. The resistance of the Gentlemen: Kindly send me a copy of 150 RADIO ROOK- is possible to obtain the correct plate volt- grid leak required is determined by the UPS .THE RADIO TROUBLE FINDER... which or both). age for the detector tube in this way, but maximum plate voltage of the power unit; Enclosed lind cents in full payment. often the A.C. hum is greatly increased. however, the correct value is usually 500,- Name A more satisfactory method is to connect 000 ohms when using a power unit with Address a grid -leak resistor, shunted by a by -pass an output of 400 volts. A modern type of city State condenser, between the plate circuit of the resistor, capable of dissipating 10 watts, detector tube and the terminal of maximum should be used.

www.americanradiohistory.com Radio News for July, 1928 81 Interstage Coupling for Screen -Grid Tubes ghe A sa of three coils, p ug -in base, (Continued from page M) rotnrx the 20, 40 and penrected 'O -meter bands. PLIJG. ANOTHER DESIGN the inductance, only half as many turns are used; i. e., 300 turns instead of 600. A circuit that will give somewhat higher COIL than the one pre- amplification per stage TUNED COUPLING TRANSFORMER viously described differs only in the design of the interstage coupling device and in the When the broadly- peaked circuits are selectivity obtained; this is shown in Fig. 2. used in the intermediate stages, a tuned The circuit as a whole is similar to that input transformer is necessary in order to shown in Fig. 1, the coupling circuit in obtain the desired selectivity. Fig. 2 replacing the choke coil Ll in Fig. 1. This tuned transformer consists of two The principal difference between this cir- "Universal" wound coils having the di- cuit and that previously described is the mensions given above; i. e., 600 turns of smaller inductance-to- capacity ratio, which No. 20 wire, an inside diameter of % -inch results in a comparatively sharply tuned and a width of % -inch. These should be FOR several seasons Hammar- circuit in each stage. This eliminates the mounted with their planes parallel and lund low -loss, space -wound necessity of a sharply-tuned input trans- spaced about one and one-quarter inches coils have been universally ap- former to obtain the desired selectivity. apart, as shown in Fig. 3. Each coil should proved by those who "know their With two stages of screen -grid tubes, this have connected across it a low -loss fixed circuit will be sufficiently selective to meet condenser whose capacity is .00025- micro- stuff" in radio. the present broadcast conditions; but not farad. The resonant frequency of this Now they may be had in con- so much so as to cause distortion. combination will be approximately 137 venient plug-in form. A set of The inductance used in this circuit is a kilocycles. three coils covers the low -wave self-supporting - forni winding of the "Uni- The use of the chokes above mentioned band from 20 to 80 meters. versal" type, with 600 turns of No. 20 -38 (No. 85) and the tuned input transformer Special coils supplied for higher Litz wire; it is important to keep the losses makes a simple circuit that will give ex- wave lengths. low. The inside coil diameter is % -inch; cellent results; good amplification, good width of winding is also %-inch. This reproduction and sufficient selectivity. Contacts are perfect. The dou- gives an inductance of slightly over eight If higher amplification is desired, in order ble silk- covered wire is space - millihenries. A somewhat smaller coil is to operate this receiver on a small loop, a wound and firmly anchored in a made with solid wire; these would be ex- third intermediate stage of amplification film of high -test dielectric ma- tremely difficult to wind evenly by hand, nuay be used. It must be remembered, how- terial. Losses are low. Short - but can readily be purchased for a small ever that, if this is done, still more care circuits are impossible. amount. must be taken to see that the shielding is The variable primary coil has For coupling from the first detector tube, as nearly perfect as possible. connec- a 201A-type, the values given above will Similar results mcy be obtained by using phosphor- bronze flexible not permit the 201A -type to be worked a good bandpass filter instead of the tuned tions and is integral with the very efficiently as a detector. It was found input transformer.. For the experimenter Bakelite base. Friction holds it that a decrease of inductance, and a cor- the tuned transformer is probably the more at any desired coupling. responding increase of capacity, greatly practical; although there are several band - improved the operation of the first detector. pass filters on the market at present that Set of Three Coils, with In the final circuit the first detector was may be used. Plug -in Base, com- worked into a circuit having an inductance The experimenter will find that the de- plete $10.00 of 2 millihenries and a capacity of .001 - gree of success lie obtains with this circuit Plug -in Coils each 2.50 microfarad. The same type of winding is kvill depend directly upon two factors, law i Base only each 3.00 used but, in order to obtain one -fourth loss and good shielding. Write for Special Folder Obtaining Suitable Screen -Grid Voltage HAMMARLUND MFG. CO. 424-438 West 33rd St., New York (Cautiailrtf fraut page .51) .`}cru RPizttth 'Radio' and plate current show that the screen Since this can be supplied by a standard current will be approximately 0.18-milliam- size of metallized resistor, capable of carry- cit11á1ailUliid pere, with a plate voltage of 135 and a ing safely far more than .018 -milliampere, PRECl/ON screen voltage of 45. Assuming that these see how simple our problem has become. It CONDENSER are the values we are to use in the circuit, is possible, in most cases, simply to con- it is evident that the series resistor must nect this resistor between the plate and I be of such size that the voltage drop across screen -grid posts of the tube socket, as it, due to the screen current, will be suffi- shown in Figs. 2 and 3; although, theoretic- Write for descriptive circulars oil cient to reduce 135 volts to 45 volts. In ally-, it would appear that the arrangement Electrad specialized controls. other words, the drop across this resistor of Fig. 1 is better. 'Phis, perhaps, is a ques- Dept. A -7, 175 Variek St.. New York City, N. Y. must be 135 minus 45, or 90 volts. tion whose answer depends on the remain- Then, applying Ohm's law: der of the circuit and the voltages used. E 90 The shielding system of the receiver, usu- It = -= -- - 500,000 ohms. ally-, forms the negative filament return and, ELECT RAD I .00018 where this is the case, it is customary to simply ground the screen -grid by-pass con- denser to this shielding system. However, RAISE BELGIAN HARES New Zealand fiedu - Chinchillas - Flemish Giants This simple Connection care must he taken to make all ground con- MAKE BIG MONEY -kV4. Supply Stock puts a .suitable high and pay y followingollowing prices or all you raise: nections Belgian Hore $2 each-New Zealands $9 each resistor- 500,000 -ohm at the same point on the shield. -C.,inchilias $4 each -Flemish Giants $5 each. 92 Dade illustrated book. and contract -between the screen - ] f this is not done, circulating currents will copy of Fur Farming ma¢azine,tells how to grid and the plate of a raise skunk, rein k, rot, ¢ profits, all for Ines P ddress 222 -type t u b e, a s be set up in the shield and undesired cou- OUTDOOR ENTERPRISE CO.. Rot ?3 Noimeo Park, Missouri shoten in Fig. 2 on pling effects will almost certainly result. page 4 suitable 51. It will, of course, be evident that this 6 TUBE SUPERPHONTe RAMP -516.95 proportion between the FREE-Six tubes, tested and matched voltages on these ele- same arrangement may be used to obtain An amazing value that can't he beat! T:atnnt. R-tube tuned ments is thus ob. aincd. radio frequency circuit. Metal chassis, shielded. Extremely the positive bias for the inner grid, in selective. Lone- distance reception. Send for complete de- :illy scriptive circular. Value SRO. our price 516.95. write today. space -charge -grid A.F. amplifiers. Radio Equivalent Co. D.12G 549 S.Wetln.St. Chlcapo,Ill.

www.americanradiohistory.com Radio News for July, 1928 SKINDERVIKEN Radio Aerials Transmitter Units (Continued from page 27) the aerial, it is an essential part of every antenna system and for this reason will be considered in this article. 'l'he electrical function of the ground has been considered in the first part of this article, and, there- fore, only the practical side of the ground installation need be discussed here. It is the object of the ground wire to .provide a connection to the earth of as low a resistance as possible and, usually, this may be accomplished most easily by con- necting the wire with a cold-water pipe. Water -pipe grounds are approved by the Have hundreds of uses. Every amateur should have Fire Underwriters, and they are far more two or three of these amplifiers in his laboratory. efficient than the usual artificial or home- A FEW USES FOR THESE UNITS made ground connection. Connection is

D SPEA ER w[.co made to the cold -water pipe by a device RETRANSMISSION-. . ... « known as a ground clamp. The ground clamp is a strip of sheet brass or copper,

4s about one inch wide, which is fastened to the water pipe. However, before the clamp is applied, the outside of the pipe should Price $1.97 ,UTTON be thoroughly cleaned in order to insure a low- resistance connection. In places where IIIIMINISIP f BAIT,. 1I^ a city water pipe is not available, a radi- ator pipe may be used; but the gas pipe D.AON AG. A rs,ottmca must not be employed for this purpose. AA \ Ii w ïóótT GAID LLAk- ,....4., AMDUfRR - Often, improved results may be obtained by using both radiator and cold- water -pipe RADIO -RADIO AMPLIFIER-. lI ...... ground connections. l On a farm in the country, where such a convenient ground is not available, it is EDUCATION . sometimes necessary to make a special -ONE STASE IN 5 VOLUMES AMPLIFICATION- ground connection. For this purpose a TO Apy metal object with a large surface, such as "THE RADIO ._ a clothes boiler, should be connected to 6P,113, . f ti owpAC. the ground wire and buried about three or EDUCATOR" : ` .,ï O JI. - ! four feet deep in the ground. This should LAND R,w be located in a place where the ground is Theory, Design, Construction, BRTON . damp at all times anti, before the hole is Operation and Maintenance DN0..0A(.. .G LY$'r0 -TAMING LIGNT. DETEGIOR filled up, it is necessary to make sure that -CODE DR ACT a good electrical connection has been made LEARN AT HOME re t :1'47.1' ,e.w.,nC.l ' to the object which is used as the ground. The wire from the receiver to the H E S E five component 'MI. I[Y oAMR ground .r ti 2 may be No. 14 copper wire. parts of a complete Radio [ ,..raW .0: , Instruction Course are outlined AFLAAA, \Ac[ - LIGHTNING ARRESTOR [.. wi, .,r [ in five volumes that contain not BALDWIN DRONE AMDLIfI@- 'l'he last, but one of the most important merely the essentials as so 12 PAGE INSTRUCTION BOOKLET things to consider when erecting an aerial many books do, but more, they containing suggestions and diagrams for innumerable is the lightning uses, furnished with each unit. arrestor. This piece of contain all that any modern up- apparatus is required by the Fire Under- to- the -minute textbook on any WE PAY $5.00 IN CASH writers' regulations, and it is connected subject would cover. They are for every new use developed for this unit between the aerial lead -in and the ground, and accepted and published by us. near the point where the lead -in enters the in themselves a COMPLETE radio education teaching every P. G. MICROPHONE TRANSFORMER house. It may be located on either the A Modulation Trans- outside or inside of the building. possible portion of Radio former specially de- As the science. signed for use with lightning arrestor has nothing to the Skinderviken Trans- do with the operation of the receiver it is Size of each book 6 by 9 inches, mitter Unit. not necessary to discuss its electrical fea- handsomely bound and illus- tures in this article. 'l'he radio fan who trated with charts, diagrams, buys a lightning arrestor should first make s2. sure descriptions of equipment, etc. that it has been approved by the Fire Each volume 52 pages. Underwriters; and, if so, he may feel per- FOR SALE AT LEADING DEALERS fectly safe in using it according to SEND NO MONEY for these Or Order Direct, the Using Coupon Below directions given by the manufacturers for books. Just forward your name SEND NO MONEY its installation. and address. We send you the When the postman delivers your order you pay him for whatever you have ordered, plus a few cents postage. books at once. On receipt of same you pay the postman PRESS GUILD. INC. R-7-23 16 -18 -R -East 30th St.. New York, N. Y. HOW TO BEAT THE RACES $1.9 7 plus a few cents postage Please mall me at once as many of tho following items (Broadcasts from Australia are heard in and then they are yours. Its I have indicated. England ten hours ....Sklndervlken Transmitter Units at 95e. for 1; 31.75 earlier in the same day. This for 2; $2.50 for 3: $3.20 for 4. bit of radio relativity inspires the following ....P. G. Microphone Transformers st $2. ingenious suggestion from an English radio and Distributed by When delivered I will pay the postman the cost of the racing fan.) Items specified plus postage. TVe''e just heard a good relay Name The Consrad Co. Of Sydney (2FC); Incorporated As their time's ahead, Address I wish they'd say, Who'll win the 3:33. 230 Fifth Ave., New York, N. Y. City State -Arthur Wolffendale.

www.americanradiohistory.com Radio News for July, 1928 83

the pulley in much the same manner. An Radio Wrinkles examination of the illustration shows how the resistor operates. As the condenser (Continued from page 47) shaft is turned, the resistor turns and the pulley is turned by the rubber band. The the resistor, which is mounted on the con- turning of the resistor unit causes more and denser shaft is varied in resistance, pro- more of the resistance wire to be short- portionately to the capacity of the con- circuited by the flexible wire. denser. When the condenser is set at mini - The arrangement illustrated in the picture mum, the entire resistance is in the circuit may be varied and simplified in Many ways. and, at its maximum capacity, the resistor In the case of condensers which have a re- is entirely short- circuited. movable shaft, the resistor unit may be The value of a device of this kind may mounted on the rear of the condenser, thus be appreciated better when it is known simplifying the construction and avoiding that the average receiver is much more effi- the necessity of removing plates from the cient on the short wavelengths than it is on condenser. Also, with this system, a slider the higher wavelengths. Because of the contact may be used, thus making possible increased efficiency on short waves, one of the construction of a potentiometer. two conditions usually exists; either the op- eration of the receiver is unstable, and there is a tendency for the R.F. stages to oscil- late on the short waves, or the receiver is inefficient on high wavelengths and recep- A Highly- Insulated Lead -In tion is comparatively poor. can he con- It is the purpose of a device of the type AN efficient lead -in insulator described here to increase the stability of structed from two glass funnels, such as are used in laboratory experiments. the receiver automatically as the wavelength TH E SECRET OF TH of the set is decreased. This is accom- These can be purchased at most drug stores plished by introducing resistance into some and, together with a long brass rod threaded STApURbD part of the circuit. Therefore, with a re- at each end, four brass nuts to fit the rod, UEfir[]In Gi.lECM ceiver using this type of unit, the circuits and two small rubber washers such as plum- the material needed to may be adjusted so that maximum efficiency bers use, complete The use of Ionised i i, limn gives assemble the insulator. The completed de- to the Raytheon "BI I" Tube a is obtained on the high waves; and then, superior ruggedness a far longer as the wavelength of the set is reduced, the vice is shown in the diagram. life and a sustained voltage. Be A hole, slightly larger than the brass sure you get a Raytheon "BH" for resistance introduced into the circuit will your eliminator when the tube be sufficient to prevent the R.F. circuits rod, is made in the wall or window through needs replacing which is generally from becoming unstable. which it is desired to bring the lead -in; every nine to twelve months. There are a number of ways in which and after one of the funnels has been placed case this unit may he connected, but in each 141 a different value of resistance is required. H it is so desired, the unit may be em- WINOOW L()rG 111E itEt:TíPYNl., TUBE.: ployed to introduce resistance into the fila- \ GLASS l GLASS ment circuit of the R.F. tubes and, in this FUNNELS case, a resistor unit having a low resist- used. Secondly, it may be ance value is OOO[[0000000000000000000/M000/MOOOOOOO/I0a0000000000000(1/5 used to vary the value of the grid bias on BeYou r Own Broadcaster FROM FROM the R.F. tubes and, for this purpose, a AERIAL SET resistor unit of intermediate value would be J needed. Thirdly, it may be used to intro- duce resistance into the plate circuit of the R.F. tubes, and a high- resistance unit will r

be required in this case. 1 method of using two glass funnels as a lead - It is impossible to give complete direc- in insulator. The threaoded brass rod which clamps the fin nels in place serves also as part ds tions for building a unit of this type, as of the ieaatu Toirc. each make of variable condenser will pre- A New Idea for a Radio Party! a slightly different problem to the on each side as shown, the rod is passed Tba afyatfe HOME BROADCASTER fe attached sent to any radio set in a jiffy. No skill Ruircd. Stretch long extension cord, hide in other room constructor. However, the drawing shows through them and one of the rubber washers or closet karma the witch button on the micro - which automatically cuts off radio tecep- the method used by the writer, and a some- is placed on either end, followed by a nut phone-rou then BEGIN TO BROADCAST. SING-JOXE- PLAY -THE SKY IS THE LIMIT! what similar arrangement may be used for which should be screwed firmly in place. A Release the button and radio reception comes Waugh once Slip a Home Broadcaster second nut is then on ion pocket when you o to the next radio other makes of condensers. placed each end of tO enpocket hat happens SEND NOeMONEY. l'oy tman $4.95 sos In order to adopt the resistor unit to the the rod, for the purpose of holding the postage for a HOME BROADCASTER OUT IT, censiating of Microphone, Special tension variable condenser illustrated, it was neces- connecting wire in place. Cord and adaptor plug. State whether Set Uses I or 5 Prong iDetector Tubes. Money back guar- sary to remove six plates (three stationary In order to install the insulator on the anteed. Elba Products Mfg. Co. _7_26 Atlantic Avenue, Brooklyn, N. Y. Dept. Z and three rotor) from the rear of the con- window it will be necessary to drill through denser to make room for the resistor unit. the glass pane a hole slightly larger than The resistor unit was made from the re- the rod. This can be clone with a small sistor strip of an old rheostat and mounted rat -tail file and a little turpentine. 'l'he on the rear of the condenser shaft. Below file should be placed in a small hand -drill the resistor unit, a pulley having a diameter and the end of the file broken off with a to of the resistor unit was pair of pliers. This leaves a equal that sharp, ragged TOBE A FILTER with any good two ampere mounted on the condenser frame, in such a edge which should be placed firmly against charger eliminates the A BATTERY way that it would rotate with the condenser the glass and turned slowly. At the same TOBE DEUTSCHMANN CO. Cambridge, Maas. shaft. time the surface is kept wet with the E C. A. "A" Eliminator, 60 cycle, 110V., output 2 3 am ,f Next, a flexible wire and a rubber band turpentine. Care should be taken not to BV SILENT-No Battery $16.00. "B" Eliminators. 150 volts. 40 mills, 4 taps, with 1180 bulb. $10.00. Model KW, 180 were required. The wire is used to short - apply too much pressure to the drill, and bulb, Has power tube. ABCEliminator, ne unit, 2 amñ 6V L"A'Qsidë circuit the resistance wire, and the rubber to see that the glass pane is laid on a a80 volts, 5 tape, 60 mills, -B," complete, $20.00. 2- ampere ^7," Metal Electrolytic Charger -Edison Electrolyte, 56.75. band is employed to keep the wire tight perfectly smooth, firm surface. Agents wanted. Catalog. Interference Eliminators, Under- wire and rub- ground Aerials. and to turn the pulley. The This insulator is satisfactory for either ELECTRO- CHEMICAL COMPANY OF AMERICA ber band are both fastened to the resistance transmitting or receiving aerials; the same Indianapolis, Ind. unit, at the point where the winding starts, plan of construction may be followed when with the machine screw which serves also it is desired to pass the lead -in wire EVERYTHING IN RADIO AT ATTRACTIVE PRICES. SETS OR PARTS. as a terminal of the resistor. Both the through the wall of a building. -M. M. Orders shipped exactly as ordered. Prompt Service. to Write for Prices. Mail Order Only. Send Your Address. wire and rubber band are also attached Dohrnlo. ALL RAOiO COMPANY, 417 North Clark St.. Chicago

www.americanradiohistory.com 84 Radio News for July, 1928

Television Demonstrations Through WRNY (Continued from vane 211 after it has undergone thorough tests both in the laboratory and in practical service, OPERATION The television transmitter is made mostly of wood, and stands about five feet high, three feet wide, and about four feet deep. 'l'he legs are fitted with casters, so that the whole machine may readily be moved from place to place. As a subject pre- pares to be "televised," he or she merely sits down in front of the "illuminator," shown on page 20. It is a square box fitted with twelve 50 -watt lamps and a highly - polished reflector. Directly behind an open- ing about six inches square in the latter is a very "fast" lens (f. 1.5) which concen- trates the image of the subject on the re- volving disc behind it, which is pictured separately at the lower right. The disc's For Real Scientifiction driving motor, which is not shown, will be placed on the baseboard in the immediate foreground. READ Behind the perforated disc is a small box containing a photo- electric cell and a three - tube amplifier. As the disc revolves and RS, allows the reflected light from the subject's uO face to pass through the small holes, one at a time, into the cell, the latter translates the light impulses into electrical impulses, which are led to the broadcast transmitter. (A close -up of the photo- electric cell unit appears in the panel above; the cell is the large round bulb at the left; the square opening in the steel can allows the light rays to affect cell in "Scientifiction " -fiction with a plausible scientific the the proper manner.) background -is the popular reading of the day. In his next article, the writer will dis- Tales of other worlds, of the future, of strange cuss his television transmitter, the amplifier happenings and weird people -this is scientifiction. and the exact method of putting the images And, in AMAZING STORIES, there is, each "on the air." month, a new big collection of this popular form of (On the very closing day of this number reading that has taken the country by storm. of Ramo NEWS, an announcement Rice was made Tales by world- famous authors: Edgar by the General Burroughs, Jules Verne, Earl L. Bell, H. G. Wells, Electric Company that sta- Miles J. Breuer, M. D.- stories by one or more tion TVGY, transmitting on its regular 380 - of these famous authors you will find each month meter wave, would commence broadcasting in this remarkable magazine. television programs on a regular schedule. The pictures will be sent from the IVOY laboratories in Schenectady, N. Y., on Tues- Amazing Stories Monthly-is a large size maga- day, Thursday and Friday each week, be- zine. Each issue is profusely illustrated. Over 100 pages. Many hours of priceless enjoyment. tween 1.30 and 2.00 p. ni., Eastern Standard Time. Only the faces of men talking, laughing or smoking will be broadcast, the announce- ment said; no elaborate effects are planned THE 25e COPY at this early stage. The regular schedule of transmission is AT ALL NEWSSTANDS OR WRITE DIRECT designed primarily to assist engineers in the development of a reliable and complete television system; but, since the signals may EXPERIMENTER PUBLISHING CO be picked up with ordinary broadcast re- 230 Fifth Ave., New York, N. Y. ceivers, amateur experiments may readily use them for the testing of television ap- paratus of their own construction. As heard from the loud speaker, the television signals have an intermittent, high - pitched whirr; the pitch varying with the action before the transmitter. This descrip- tion is contained in the announcement. The television transmitting apparatus is a . modification of the Alexander,son machine

/ described in the April, 1928 number of ` . RADIO NEws. No information on the con- struction of receivers suitable for the re- production of the broadcast images was \Ç Vv%11°. available at the time this number of RADIO

%,_44101 News closed; but, as soon as the data can be presented in useful form, RADIO NEWS \ will publish them.-EDITOR.

www.americanradiohistory.com Radio News for July, 1928

very noticeable; but the average radio bugs The Listener Speaks care more for a combination joke book, (Continued from page 18) movie magazine and so forth than they would for a purely technical radio maga- grovel, remainder of the Dominion, the whole of it, zine. I have also noticed the entries in the goes to maintain the federal radio depart- "wrinkles" contest; they are, many of them, ment. Thus, the people who use the radio ideas which have been in use for years but Positive pay for its regulation. The Dominion gov- are necessary for the beginner. Voltage Control ernment maintains in most of the large I base my opinions on observation, as cities interference cars to locate noises both an operator and an occasional B. C. L., for Radio Power Units which interfere with reception, and I believe and not on what so- called experts say or work. This also is paid The new Centralab Heavy-Duty Po- they are doing good think. Lf my opinion, Mr. Chambers had tentiometer is all wire wound and will for out of the dollar license fee. It will is about; for it carry the entire output of any "B" better know what be talking high a lot to convince me that Manitoba is power device with an unusually take amounts to tither foolishness or superlative margin of safety. not as near a radio paradise as can be found imagination to say that "the N. B. C. has Resistance re- on the North American continent. to $20 a year." mains constant at the crust to ask us to pay $3 any knob setting, W. C. TRE1tLETT, This alone should be enough to show what a so that panel or his biased argu- knob can be Suite 1, Carlyle Apts., Broadway, foundation he is building marked in volts. Winnipeg, Manitoba, Canada. ments on. Yours for the best in radio. A single turn of JOHN M. THOMIPSON, 8AWG, the knob will give full varia- Canandaigua, New York. tion. II a s sufficient current carrying capacity to permit shunting a low resistance value across the "B" power unit to obtain constant Business is Business Nobody Loves a Soprano voltage regulation. A sufficient cur- rent load is maintained throughout the the rectifier volt- Editor, RADIO NEWS: (By Radio) resistances to reduce age to workable pressure, even though magazine dat- Editor, RADIO NEWS: set is not connected-an insurance I have on file copies of this against filter condenser breakdown. ing back to January, 1920. If Mr. D. V. Kindly keep the girls off the front cover. folder giving details Chambers has been a reader as far back as is bad enough to listen to sopranos over Write for It this circuit. that, he should know something about the air without seeing them on the cover of of code, as RADIO NEWS was the operator's my favorite radio magazine. Resistances: 2.000, 3,000, 5,000, 8,000, be- 10,000, 15,000, 20,000, 50,000. Price, $2.00, bible in those days before broadcasting \1'lly don't you put pictures of Marconi, at your dealer's, or C. O. D. cahie so popular. If he knew half as touch de Forest, Armstrong, Edison, Hertz and as he claims, he would realize hunt 99.9% of Fleming on the front cover? If the B. C. I,.s commercial broadcast is strictly business, don't like them, they can throw theist into < CENTRAL RADIO LABORATORIES Wis. and of more importance than the broadcast- the ashcan. 'These men made radio; but < 19 Keefe Avenue, Milwaukee, ing of programs of music, prize tights, ami where are their pictures? The only place so forth. Even if he is bothered 1w com- I can find most of then) is in the N. It. 1. mercial code work, why should he blame the lesson hooks that I am studying now. poor operators? They are not responsible D. 1). BARTHOLOMEW, for the sometimes -antique transmitting out- 221 So. 'Third Ave., Bozeman, Mont. fits which they have to use. Rather lay the T blame at the doors of the owners who sup- DEPENDABLE "B " BATTERY POWER plied the apparatus and do not care to re- Chain Program place it with modern equipment. International Of course, the change in RAUIo NEWS in Europe which J. E. Kitchin mentioned has been Editor, RADIO NEws: At last, Germany, Belgium and England are linked up by land line, and it was rather fascinating to hear time German an- IN OUR /` JULY ISSUE nouncer at Cologne say last night, at the conclusion of an act of The Marriage of Vandals from the Moon, by steamship imitates Figaro, "Hier die Sender Aachen, Münster, 100 Volt Edison Element. Marius. The Non Destructive, Rechargeable "B" Battery with the fish in its manner Of loco- Küin, I.angenberg, der Deutschlandsender charger. Shipped dry with solution. SI ?. 140 Volt with motion, the airplane imitates the charger. $17. 180 Volt Power Unit with Trickle bird; but no engineer scents ever l:ünigswusterhausen, und die Sender Daven- Charger, $24.00. Free sample cell. See how it have thought of duplicating operates. to i ry, London hind Brüssel " -rather a mouth- for propelling heavy SEND NO MONEY -PAY EXPRESSMAN he snake's motion till Write for our Free Illustrated 24 -page Booklet bodies. Yet it is perfectly plausible. and ful for the first such stunt. Wait SEE JA Y BATTER Y CO., 915 Brook A ve., New York the author of this story may prove to be Stamboul, Paris and Budapest, etc., are all a prophet some day. It is certainly an interesting and original idea and furnishes linked 111. 'lime whole "do" was quite slit' - excellent material in a unique interplanetary tessful. EARN. CODE talc, this time dealing with the moon people E. T. SOMERSET, :el, a Teleplez. the remarkable instrument that who visit our planet. reproduces salmi sending. uses perforated The Invisible Man, by H. C. Wells. Part Inholmes Park, Burgess hill, Get the rapes-principle similar to player-piano. Ex- this I pert operators send you messages, radiograms 1L In the conducting chapters "i Sussex, England. TH R L L regular code trame. Slow at first. Tben they story, the harassed and harassing invisible .need you up. Complete rese.ic Morse or wlre- man finally reaches an old scientist friend of te.st The lessons are In the record tapes. You of his, to whom he relates his experiment-. REIL "listen and learn... Easy, quick, thorough. his success and his subsequent Teleplex endorsed by U. S. Navy. Remember unexpected only code brings you the thrill of real DX experiences. But you don't need to be a A Listener's Directory DX Write for booklet NR7. dyed -in- the-wool scientist to become thor- oughly absorbed in the story of their sub- I:tlital-, RADIO NEWS: TELEPLEX CO.. 76 Cortlandt St., New York. N. Y. sequent experiences. Baron Münchhausen's Scientific Adven- Mr. Woodruff continents on Chicago an- tures, by Hugo Gernsback. (Conclusion). nouncers "dedicating" selections to "So -and- ages from RADIO SCHOOL \Vhat will our descendants do So" at Kansas City during daylight hours, now. when their air supply dwindles down Send for Catalogue to nothing? According to our very remark- %Then, as he says: "I am sure that there the Baron, the Martians have able friend, %vas a chance that the lady MASSACHUSETTS RADIO and already solved this problem by their marvel- not ghost of a ous invention of air plants. with which they heard even the carrier wave." TELEGRAPH SCHOOL generate their own air. The Baron tells us Now, I ani not a fabulous DX hound, 18 Boylston St. Boston, Mass. also, how the Martian canals were built. and, lest we think them always serions and but I receive stations WGN, and KYW and scientific, we are permitted a glimpse into its sister station KFXF daily during day- their lighter moments. A-C FILAMENT TRANSFORMER light hours, with a good loud -speaker vol- Just Around the Corner, by Raymond Supplies stepped down current from ONLY $47 Knight. We offer this interesting playlet, ume. It is now 11 a. m., January 27, with 110 volt 50-60 cycle lines for six type which in a sense is based on science, as a the sun brightly shining, and I have just 226 tubes, two type 227 tubes, and two type 171 novelty to our readers. tubes. Guaranteed. Only $4.87. Order today. Money And others. had WGN, KFXF, and WMAC, with good hack If not satisfied. W. volume. Illinois Transformer CO. Dept Chicago

www.americanradiohistory.com 86 Radio News for July, 1928

Recently, I brought in WLW, WSAI, WJR, WWJ, WJZ, and WEAF in the afternoon, at 4 o'clock, when the sun was shining here. Since then, I have had WJZ during the afternoon. KMOX, 200, and Davenport, 275 miles, arc regular daylight features, as are some twenty other stations within a 200-mile radius. I have a combination set, which consists of a "Penetrola" as first R.F. stage. 'l'hen a six -tube Atwater Kent, No. 30. Last 1 have a power unit, 180 volts, making eight tubes in all. I have an underground an- tenna running into the Penetrola. Between the Penetrola (first stage) and the A.K. (second stage) I have inserted a light - socket antenna, through an adjustable con- denser. It is only since I introduced the second antenna that I have succeeded in obtain- ing the daylight DX, and I cannot do it without it. What has occurred, I don't know; I accidentally stumbled on the hook- up. W. H. HEYSER, 3340 Montgall Ave., Kansas City, Mo. The funniest comic in America 'Smatter Pop? will keep you in stitches 'from the moment you open it until you have read Where It Comes From and reread every . page time and time Editor, RADIO NEWS: again. Fifty full -page comics in this edition of 'Smatter PopP- Hundreds of I ant sending you a solution to some of real laughs. C. M. Payne sure knows the mysteries; I have read of an experi- how to get under your skin and bring menter who can bring in music without out every laugh in your system. aerial, speaker or phones, but who cannot explain it. I can go him one better; any set using an output filter to protect the windings of the speaker will do the same. You can remove the diaphragm from the Meet "Pop," "Desperate Ambrose," and Pop's little phones, and hear the music in them. 'l'hey family. They can make you laugh when everything have a winding with an iron core -and so else has failed. Ask your newsdealer or, if he can't has the output choke. If a diaphragm supply you, fill in the coupon and mail to us. The were attached to the choke, you would funniest comic ever written. Don't miss it ! Get your have volume as from your speaker. copy now ! Barrels of FUN ! I have also received telephone messages from my radio and loud speaker, and spent two days figuring it out. If anyone would like to have the solution, I will give it on request. EXPERIMENTER PUB. CO. 230 FIFTH AVE. WM. J. Bsooxs, NEW YORK CITY 112 Warren Ave., Milwaukee, Wis.

LISSEN - -- 'SMATTER POP IS WHAT I'M (The composite nature of the core of the LOOKING FOR . SMATTER POP I SAY! SO filter choke -very thin insulated sheets - DONT HOLD ME UP. DON'T HOLD ME UP will magnify this effect if they are in the MAIL MY COPY NOW - - NOW I SAY--- - slightest degree loose. For a like reason, HERES MY TWENTY - 60 -cycle hum may often be heard from a FIVE CENTS SO RUSH . transformer. Suitable mechanical clamp- NAME ing of the core will very largely overcome ADDRESS this. The choke is not meant, however, to CITY. STATE be a rival of the loud speaker, but by its APOiDG.ES T°C PAyNE high impedance to drive as mulch as pos- sible of the music back into the loud speaker. A similar letter has been received RADIO also front Mr. J. Millman, of Denver, Colo. THE SOUL OF -EnIras.) GOLDEN BEAR SPEAKERS embody the most advanced t9ealeVe, iVgÉÁKÉR principle of air column con- struction. They reproduce both music and voice with full and natural tone Return Card Attached values. They afford greater amplification without distortion and have the full Editor, RADIO NEWS: being very compact, range of reproduction. Made especially for manufacturers, I wish to take exception to Mr. Dun - for catalogue. Manufactured by with long tone travel. Write can's complaint in March RADIO NEWS, Los Angeles St., Los Angeles, Calif. M. J. CARLS, 1929 South that he gets no answer to his letters sent to broadcast stations. I do not think this is fair to the stations, as I have written to The for Free Catalo 78 of them and have received to date 72 SendAirplane Cloth Speaker answers. Perhaps it is because I have "Research Worker" Also contains many bargains in all types always enclosed a two -cent stamp for a of Cone Speakers, Units, complete parts to le a free monthly folder that will keep you abreast of the build all types of cone speakers. Also the reply. I realize that stations receive thou- latest developments in Radio. latest parts of the New AIRPLANE Cone sands of letters each day, and for them on the mailing list on request. Your name will be placed Speaker. Accessories. to answer each one and pay the postage ACCUSTI-CONE, 1 No. 7th St., Phila., Pa. AEROVOX WIRELESS CORP. would be prohibitive. I think I have proved 68 Washington St Brooklyn. N. Y.

www.americanradiohistory.com Radio News for July, 1928 my point that the stations will more than 8:06 A. M. -KFRC, San Francisco. Frank verification if you Black and orchestra playing "Ricket Rackety meet your request for Shack," and "Together We Two." will enclose the pos tage. 8:10 A. M. -KPO, San Francisco. Wilhelm Cox Improves .l. M. DILLox, playing on the pipe organ, fállowed by "second 412 No. 18 St., Richmond, Ind. class in exercises." 5:17 -KMA, Shenandoah. Giving a recipe on A-C reception "How to make a Hawaiian pie." Editor, RADIO NEWS: 8:20 A. M. -KNX. Exercises. -saves tubes! a list of stations that I 8:26 A. M. -KSL, Salt Lake. Staging a dog I am enclosing fight with WNAX (same wavelength and power), This small and inexpensive de- logged between ,January 21st and February but manage to distinguish KSL singing "Sweet 21st, and you can see what results I had. Rosie O'Grady." vice makes tubes last longer. 8:28 A. KTATI, Lady There is a total of 216 stations; and 1 got M.- Oakland. singing, Eliminates extraneous tube followed by a talk of healthful breathing. 199 noises. Does away with most, buy card or a stamp from of them- 8:38- KMf1C, Kansas City. Playing old -time which is, I think, very good. stuff. including "Casey Jones," followed by wild if not all, of the noises that I used a double (stamped) post card jazz. come over your house current on the return card. I re- 8:43 A. M. -KFWI, Frisco. Man telling us with my address where to take an old felt hat and for three dollars line. The ceived 165 of my cards back, 27 letters, have it made into a fine hat; also a talk on Edge- 4 stamps-and three wanted a dime before worth tobacco, how to get a free package cigarettes, Wirt A -C Voltage Regulator they would send a verification. I think etc. adds perfection to an already satis- 8:50 A. M. -KFYR, Bismarck. Hawaiian everyone would have better luck if they music, followed by lady singing "Home Sweet factory set. It permanently safe- enclosed a return stamped envelope or card, Home." guards condensers, tubes, etc., and self-addressed, with each communication. 8:55 A. M. -Des Moines. Back to WHO again; prolongs their life. Ask your deal- this time a man telling us how to make a steamed It. H. SUMMERS, cherry pudding. er to show 54 Fairwood Ave., Pleasant Ridge, Mich. At 11:35 A. M. I sneaked away for ten minutes you the new Easy to install and got: "A -C Volt- WIRT WHO, Des Moines. Orchestra playing "Sun- age Regula- AC VOLTAGE (Of time 17 stations from which Mr. Sum- rise." tor, No. 211 ". REGULATOR replies, about half KGW, Portland. Piano INDICATOR mers failed to receive and violin playing "O If he cannot were Canadian whom the postage sent Solo Mio." -to KFNF, supply you, The reply cards which are Shenandoah. Henry selling the farmers t.us useless. clover seed and telling them about seed inocula- get real A -C good within the United States cost only tion. WCCO, satisfaction two cents -one cent each way -at any post- Minneapolis. Man telling us about mail by sending things much easier for received from many states and reading a letter office, and make from a listener iu Montana. your dealer's the stations. To the correspondent of only PINS TO KO. \, Denver. Giving us weather and market name and TVRN THIS CONVENIENCE ordinary activity, it would come as a sur- reports. RING TO -OUTLET $2.2 5 direct CONTROL prise to be in any office where hundreds I find that, after about three o'clock to VOLTAGE and thousands of letters are received daily; p. in., in winter time, stations come in good appreciation of the task quite often. I can almost always pick up a WIRT COMPANY and bring a better Pa. which would be involved in answering few stations, during the middle of the day, 5221 Greene St., Philadelphia, of a ' and "Dim -a- lamp" ihenm. RADIO NEws receives an ea0r'nlous a thousand miles distant but too much am- Makers "Dim- -lite atnaber of letters daily; and, interesting plified noise to make the stuff worth listen- 'though many of theta are, several times the ing to. All right, now, "you" are next, and present staff would be required to answer come on with your proof. all of them at length and chattily, as we B. C. HAZLETT, would like to do.- EDITOR.) Box 379, Livingston, Montana.

What a Listener Hears 400 Miles from a Local ?.tcd.l Editor, RADIO NEWS: IIaving read, with interest, reports from Editor, RADIO NEWS: w....a...... - Used in Anent your readers on daylight reception, I de- the much -talked -about daylight re- Every High Grade Circuit cided this morning to tune in a few and set ception of broadcast programs, I would like to put in a word or two. A glance at a or Receiver Today! up a mark for the boys to shoot at. MODEL "N" VARIO- DENSER-Micrometer ad- I am something of an old -timer in the neap will show anyone that, here in Kirk- lustment easily made, assures exert rscWatlon eentrol. land Lake, we quick, easy tun- gaine, having had my first set, a three - are more than four hundred ing, more volume. »miles from our "local" we clearness and Sta- tuber, the winter of 1922. I now use a stations; and yet han)*. CapacltY Bremer -Tully six -tube Counterphase, 110 receive all kinds of broadcast programs micro-micro-range 1.8 to 20 feet of antenna, including lead -in. I ant throughout the day. farads. Price 31.00 showing Mountain Standard time. Every- Beginning with the time we get up, I have Mode! (; listened in to four different stations Made in 3 oasiatw capacity caneea; trite, 51.511. thing out here is DX, and I and giving proof broad- dfoagoms FREE alll of reception by mentioning something from casting setting -up exercises. I have fre- ofg leading ccirrcuits..°Write today . each station. I picked up vsl'iat,S other sta- quently listened to WCCO broadcasting tions but they refused to identify them- phonograph music, for as much as two hours selves and I had only a limited amount of at a time. We have had beauty hints from XI-Radio Laboratories time. a station in Toronto at 11:00 a. m. We have Dept. A, 1221 Belmont Ave., Chicago, 111. 4, Practically all the stations I am listing are often set our clocks by WLS or KYW at a thousand or more miles distant, several 1:00 E.S.T. WOC often comes in fairly being round twelve hundred, and Fort loud in daylight. ANEW and WEAF have NEW WAY TO PROVE frequently been heard in mid- afternoon. DX RECEPTION Worth, I believe, about fifteen hundred 'Seeing is believingK." What All this has been with a Sparton 6 -tnhc DX FANS you SAY about DX recep- miles distant. The volume by no means tion is never as convincing as tuned- radio -frequency receiver, with a sixty - what you can SHOW. Get a bigger "kick" from your long enough to jar the rafters, but about equal distance success by using the new RADIO DX MAP and I no kick foot, two-wire "T" antenna; and a poor VISIBLY record every station In U. S., Canada, and Mexico. to conversation. get particular On heavy mat board. 13'x19'. almost S4' thick. Complete. out of daytime reception unless it is some- (comparatively) ground connection. There is with 250 colored markers. 52.00 postpaid: C.O.D. 32.23. thing very special, because the signals being very little earth here soft enough to put in a RADIO MAP CO., 210 J W 14th St., Los Angeles. Calif. naturally very weak must be highly ampli- good ground; it is all solid rock. fied and, in doing this, the local noises, Just by the way, this same receiver has broken every local record for distance. static, etc., come in abort as loud as the i\ KFI has been received with a volume of MERSHON1* broadcasting. I use a 201A detector. CONDENSERS about R5. Our list includes WBAP, KGW, For full Intormat on address Department RN. (Mountain Standard Time) THE AMRAO CORPORATION \ TSB, KFRC, KEST), CFCN, KRLD, KPO, Medford Hillside Massachusetts 7:55 A. M. -WHO, Des Moines. Orchestra playing "We." KWKII, CKY, KHQ, KVOO, KJR, KOA, 5:00 A. M.-KMTR, Hollywood. Setting -up ex- CKCK, KOMO, WIOD, and several dozen ercises. of others. I have picked up \VBAP and P nDUCTS 8:04 A. M. -WRAP, Ft. Worth. Announcing KOA within an hour after sunset. The for- 10 points higher; New Orleans cotton market 8 to was while ON SALE EVERYWHERE market closed account Mardi Gras celebration. mer picked up WEAF was

www.americanradiohistory.com SS Radio News for July, 1928

broadcasting; the latter was not interfered with by either KDKA or WBZ. So much for selectivity, is merely an appetizer. Here's sonic wore -I find it easy to listen POPULAR in to either WIP or WLS without inter- ference from the other. I have also been able to enjoy the evening chime program MODERN from WOC while WGY was going strong. I have found, though, that it is almost im- possible to get WIOD while WOK or MOVIE WMBB is on the air; they also prevent me from hearing KTNT and they even hetero- dyne with WFIW. NOVELS I don't think that there is another set re- tailing for less than $150 ($200 in Canada) that can duplicate this record from this lo- GREATEST OFFER EVER MADE cation. There are about ten other makes of radio sets used and sold here, including a couple of superhets, and they all have to Take Advantage of Titles of This An Addition To admit that a 1 -dial, 6 -tube Sparton can run This Amazing Tremendous Bargain Offer Your Library rings around them. Guess what kind of Bargain radio I'm agent for!! 1. New York will Thank you, Mr. Editor, for an audience. size These books Eight full books 2. The Campus Flirt I like RADIO NEWS; and think it is the one dollar. Never be a worthwhile best for 3. magazine in its before has an offer of Almost a Lady addition to your field. 10. Sensation Seekers TIIOarAS C. RUDIN EY, this kind been made. You will Only quantity produc- 11. The Rambling Rangers library, Kirkland Lake, Ontario (Canada). tion permits us to make 12. Don't Tell the Wife find many hours this astounding offer of truly enjoyable now. Take advantage 14. Tracked by the Police of it while you have 15. Tell It to the Marines reading in each Sun -Maid Reception the opportunity. Need- 19. Irresistible Lovers beautiful volume. Editor, 11 Arno NEWS: less to say these mod- 20. The Cohens and Kellys Printed on fine pa- Having read Mr. Woodruff em up-to -date movie 's article in hits cannot last long In Paris per with large clear the February RAnro NEWS issue and his at this tremendous bar- 21. The Divine Woman type. Beautiful doubts about distant daylight reception, I wish to give gain price. Each book 22. Jazz Mad colored covers of my experience with a three - contains at least two 23. The Crimson City tube set I just recently constructed from color "stills" of an flexible durable ma- an old copy- of RADIO NEWS, 24. You Can't Beat the Law December 1926. actual scene from the terial. These books ('l'he Universal All -Circuit Set, by 25. Tillie's Punctured Joseph photoplay. Don't hesi- are undoubtedly Riley.) tate. Mail this coupon Romance While writing this letter I am listening now. Every one of the greatest story 26. Forbidden Hours to a Columbia Orthophonie concert based on an actual values ever offered from moving picture tri- Salt Lake City, Utah. They just finished umph. The greatest 8 BOOKS FOR $1.00 at this amazingly playing "Cavalleria Rusticana" and "Laugh- book bargain of the Your Choice low price. inn Charlie." It is now 4:30 P. M. and the age. sun is shining bright in Fresno, California. At night I play WBBM at Chicago, KOA, Write Now ! Don't Wait ! Titis bargain cannot last long at this price Denver, WCCO, Minn., CNRV, British Col- umbia. One night I picked up WFIW, Hopkinsville, Ky. The set has very little CONSRAD COMPANY, INC. body capacity for a blooper and by careful 230 FIFTH AVENUE NEW YORK, N. Y. handling I can operate it all evening with- out making it squeal. G. E. GRAY, CONSRAD COMPANY, INC., 230 Fifth Avenue, New York, N. Y. 2939 El Monte Way, Gentlemen: Enclosed find $1.00. Kindly send me the books listed by number herewith: Fresno, California. Numbers Name Under Heavy Fire, But Not Address Cool City State Editor, 'Unto NEWS: -! After suffering every possible and impossible criticism, broadsides from the Navy, gentle pokes it la Dempsey from South, North, East and West, gentle hints A REAL SPECIAL OFFER! to buy a better set, delicate suggestions NEW KATHANODE AUTOMATIC that Ì ought to be thankful for living so RADIO "A" POWER GOULD UNIPOWER far from so- called local stations - The New and Improved Gould by nished Gould. Its high capacity Now, folks ! Let's see what we have here. Kathanode Unipower type AC -6K makes its especially adaptable to (6 volt). Automatic "A" Power heavilÿ worked or power tube sets. In the first place, I have a four -tube "Dya- -in dyne," Unit with built relay. Throws Equipped with a noiseless Balk - sensitive, "detective" enough to get the charger on and off and controls ite Charging Unit, which has four New York and the Pacific coast and Can- a "B" Battery Eliminator if one is graduated charging rates, and in adian stations, with volume enough to han- to be used. addition one booster rate (IM Fundamentally different from amps.), which always keeps the dle a three -foot cone speaker; selective any other automatic charging "A" battery fully charged. enough to separate KDKA from KFA13, power device on the market. Its Kathanode construction insures Operates on IIO -120 volt, 6o KMOX from KSL. But what it cannot do longer life and is an exclusive cycle A. C. is to separate stations when they bombard patented feature, being used by the Send P. O. M. O., or will ship it from north, east, south and west on the LIST PRICE $39.50 U. S. Government in their sub- upon receipt of 20 per cent of saine wavelengths. Imagine a receiver suf- marine batteries which are fur price, balance C. O. D. EXTRA SPECIAL $15.50 fering the bombardment of 700 stations. AMERICAN SALES CO. 19.21 WARREN ST., N. Y. C. LOUIS MARQUARDT, "A Listener," Hague, North Dakota.

www.americanradiohistory.com Radio News for July, 1928 89 Letters from Home Radio Constructors (Continued frone page 53) New AERO Circuits For Either Battery the tubes in a broadcast receiver mean a good kindly write and let me know what results they bit in getting distant reception. This may help are getting? or A. C. Operation many a DX listener; but I suppose this letter will EVERETT J. RANKINE-, end like a good many of the rest, in the waste- Port Morien, Cape Breton, N. S., Canada. Proper constants for A. C. operation of the basket. improved Aero-Dyne 6 and the Aero Seven have If your set is not working the way it should, been studied out, and these excellent circuits are don't think it is a "lemon." There is always a HIS FIRST EXPERIENCE now adaptable to either A. C. or battery opera- cause for lack of selectivity and volume. The Editor, RADIO NEWS: tion. A. C. blueprints are packed in foundation first to do in like is to units. They may also be obtained by sending thing a case this take your I have completed the Peridyne Five from the to a radio dealer and have him test them. 25e for each direct to the factory. tubes RADIO News articles. I had a hard time, for it less than Test your "B" batteries; if they test was my first experience in building a set. I cer- 40 volts, it is time to discard then. Test your tainly appreciate the result, for the set is working "A" battery. wonderfully. On Friday, April 6, I tuned in three After this, I would suggest a 112 -type in the stations from California and two from Mexico. I a 112A -type in the first R.F. stage, last A.F. stage, will close with "Best of Luck." and a 200 -type as the detector. This combination Louis LIMPENS, is advisable, however, only when Sion are using 177 W. Amesbury St., Philadelphia, Pa. two "C" batteries and have 135 volts "B" available. With the above combination I have received, and AERO Universal Tuned Radio Frequency Kit have verifications from, EAj22, Salamanca. Spain; News: OAX, Lima, Peru; 2L0, London, England; 1RO. Editor. RADIO Especially designed for the Improved Aero- Rome, Italy; HHK, Haiti; C1 J, CZE, CID, Mex- t wish to congratulate you on your new hook -up, Dyne 6. Kit consists of 4 twice-matched ico City; 6ííW, PWX, 7SR, 6L0, 6XJ, Cuba: the Peridyne. I have built otte of them and find units. Adaptable to 201 -A, 199, 112, and the have brought it most satisfactory. It is very selective, has new 240 and A. C. tubes. Tuning range be- anti several Pacific Coast stations. I low 200 to above 550 meters. in Hawaii, and my log totals 410 stations with plenty of volume, and is great for DX. I enclose in selec- this combination. a log I made out on Jan. 2, which may be of This kit will make any circuit better to tivity, tone and range. Will eliminate losses The antenna is au important factor in DX recep- interest you. and give the greatest receiving efficiency. tion, but its tuning is still more important. If In addition to the stations listed on the log he- low, I have reached to PWX, IIavana, Cuba, nearly Code No. U- 16 (for .0005 Cond.) $15.00 your tuning is broad, a wavetrap will increase Code No. U -163 (for .00035 Cond.) 15.00 your selectivity and also increase the volume on every night. low -wave stations. I have experimented with sev- 11'avelcttgth, Dial Time, eral types; that I find most effective has an inner Meters Reading P.M. coil 21¡ inches in diameter. with 7 turns of No. 22 Ii\\'K, St. f.ouis (local).... 234 30 7:00 silk -covered wire (in shunt across the aerial and KFKIì, Milford, Kans...... 241 33 7:05 ground posts on the set) and an outer coil, 3 inches KTNT, Muscatine, Iowa.. 256 39 7:15 in diameter, with 78 turns of No. 22 silk -covered WBT, Charlotte, N. C 258 41 ":25 wire, tuned by a 13 -plate condenser of good quality. WPG, Atlantic City. N. J 272 46 7:40 I am using an ordinary 3 -dial, 6 -tube factory -made KMOX, St. Louis (local) 300 54 7:45 broadcast receiver. KF.\B, Lincoln, Neb 309 61 8:05 AERO Seven Tuned Radio Frequency Kit CHAS. J. ANCSTADT, KO.\, Denver, Col 326 63 8:10 Nashville. Tenn 337 66 8:14 Especially designed for the Aero 7. Iiit consists 822 N. Front St., Reading, Pa. WS\l, Coils are wound on 4 City 341 67 8:20 of 3 twice -matched units. \'IIIm. Kansas Bakelite skeleton forms, assuring a 95 per cent Ií\-00, 'Tulsa, Okla 349 70 8:24 Tuning range from below 200 to 8:29 air di- electric. BETTER ON SHORT WAVES \ \' S.\ f, Cincinnati, Ohio 361 72/ above 500 meters. Adaptable to 201 -A, 199, J J D, Moosehcart, 111 366 74 8:31 new 240 and A. C. tubes. Editor, RADIO News: \ \' 112, and the \VOC, Davenport, Iowa 375 75 8:48 There appeared in the July, 1927, number of Code No. U- 12 (for .0005 Cond.) $12.00 \V 1111M, Chicago, Ill 389 78 8:50 No. U -123 (for .00035 Cond.) 12.00 RADIO NEws, Code a blueprint and layout for an 18 -1,500 KM. \, Shenandoah, Iowa 394 80 8:53 meter receiver. I built this set, using the speci- HERO Universal Kits for use in tuned «'CCO, St. Paul. Minn 405 82 8:57 NOTE -AU fied parts. it works extremely well on the low radio frequency circuits have packed in each coil with WGN, Chicago, 111 416 84 9:03 a deed primary a Lutes matched calibration slip shcuing wavebands, up to 200 meters. But on the higher Coil \ \'JZ, New York, N. Y 454 89 9:14 reading of each fixed primary AERO Universal waves there is practically no volume at all. This at 250 and 500 meters: all Wring an accurate and similar KYW, Chicago, Ill 526 94 9:30 these slips. They're valuable set is a distance -getter on short waves. I have calibration. Be sure to keep Louis (local) 545 ipo 9:35 if You decide to add another R. F. Stage to your set. heard 5SW. England, and PCJJ, Holland, several KSD, St. times, also three California stations. The greatest I am using home -made R.P. transformers, as I A NEW SERVICE thrill I ever had in reception was when I heard have been unable to locate any manufactured ones Tomsk, however, written to the We have arranged to furnish the home set builder Siberia. in St. Louis. I have, for \\'nuld a This will un- with complete Foundation Unita the above amateurs who have constructed this set TTammarlund Company for set. named Circuits, drilled and engraved on Westing- doubtedly clear up the trouble of crowding the house Micarta. Detailed blueprints for both 11111111.111M11111411,04111101111111111111111 iiiiiiii 1111111 tttttttttttttt 1111111111110111 ...... 1111110111 lllllllll111111 llllllllllll upper half of the dial, which I am now experi- battery and A. C. operation and wiring diagram encing. for each circuit included with every foundation You will undoubtedly note this from the log. unit free. Write for information and orices. Furthermore, from 450 meters on up, the volume 40 Non -Technical diminishes greatly. How can I improve this? I You should be able to get any of the above would appreciate an answer if you can spare the Arno Coils and parts from your dealer. If he should be out of stock order time to answer this, as I can sell a few of these factory. Radio Articles sets, but do not like to, do so until I clear the direct from the of the dial. every month for the beginner, the layman upper end and those who like radio from the non- L. R. CARTIER, AERO PRODUCTS, Inc. technical side. 405 Second Street, O'Fallon, Illinois. D,-ri . 10; SCIENCE AND INVENTION, which can 1772 Wilson Ave. Chicago, Ill. be bought at any newsstand, contains the (The crowding described is due either to a low largest and most interesting section of maximum capacity of the tuning condensers used, radio articles of any non -radio magazine or to a spacing of the turns of wire on the coils in existence. greater than that on those used originally, in all probability. ifhen the spacing is too great, the in- Plenty of "How to Make It" radio arti- ductance is reduced, and therefore the readings on WILL SAVE YOUR cles and plenty of simplified hook -ups for $200 SPEAKER the layman and experimenter. The radio the dal are altered. Factory -made coils are ma- section of SCIENCE AND INVENTION chine- wound, and therefore uniform. When these The Craftsman Dollar is so good that many RADIO NEWS coils are made at home, a thread slightly smaller Speaker Filter is Guaran- readers buy it solely for this feature. than the wire should be used for spacing turns. teed to relieve your speaker .Sec RADIO NEWS for December, 1927, for construc- of the DC plate current tional details of the Peridyne Five.- Enteoa.) (up to 250 volts). It gives speaker a chance to oper- Radio Articles Appearing ate at its best. Attached in a second. Send dollar in July Science and UTOPIAN RESULTS ON FOUR TUBES bill NOWI Editor, RADIO NEWS: Invention Magazine Having for over two years been an ardent ad- CRAFTSMAN RADIO PRODUCTS mirer of Messrs. Browning and Drake's idea of 9 Orchard St. Newark, N. J. RADIO STORY OF THE "BREMEN" building an efficient receiver utilizing only two A RADIO TAXI tubes in the business end of the set, I have often ANTENNA SLEET REMOVER wondered why your magazine and others have faded more space to it than it has had. A NEW ELECTRIC SET to give ACME PARVOLT CONDENSERS (This letter Was written before the announcement SECRET RADIO TELEPHONY By -pass and Filter Condensers in all required of RADIO NEws' new policy. -EDITOR.) MFD capacities and working voltages. Filter NEW RADIO DEVICES I have a home -built set of this type that has Condensers supplied in individual units or in RADIO ORACLE anything in this section skinned a city block, re- completely wired and housed blocks for the LATEST RADIO PATENTS gardless of whether it he a T.R.F., Ncutrodyne or more important power amplifiers. Made by The ACME WIRE CO., New Haven, Conn. RADIO WRINKLES what -not. I have verification cards from KVOO, nearly six hundred miles north, for daylight re- Manufacturers of Acme Celatsite Wire- ception (noon) and I hear them any time of the high insulation value, non -inflammable.

www.americanradiohistory.com Radio News for J: iy, 1928 T

MAGAZINES O?" THE ICE

A year's subscription to these Canada and in Europe. This list two popular magazines for the of call letters is carefully checked price of Radio News -alone. If and corrected in each quarterly you were to buy Radio News and edition. Radio Listeners' Guide and Call RADIO NEWS is read each Book individually for one year month by more radio enthusiasts they would cost you $5.00. By our than any other publication in the special combination yearly sub- field. It contains the latest devel- scription rate you can get both of opments and the most modern cir- these foremost radio periodicals cuits of the radio world. Honest, at the tremendous bargain price of unbiased opinions on every sub- $3.00. In order to keep up with ject of interest-this is what the latest developments of Radio, RADIO NEWS gives you.

92 Radio News for fitly, 1928 Radio News Laboratories (Continued from paie SS

a range of 2 to 2.8 volts. This tube :.eay be used very successfully either as a detector as a radio or audio amplifier. It requires 45 volts cm the plate as a detector, and a voltage up to 1f0 as an ampli- fier. Its dynamic characteristics ;,ry with the filament and plate voltages. With a re rr.al filament voltage of 2.5, the characteristics arc :< !nllows:

.ate Voltage 45 90 130 Amplification constant (mu)...... 9.9 10.4 10.6 Plate impedance (ohms)...... 7200 5700 4900 Mutual conductance (mhos) 1400 1800 2140 A very important feature of this tube is that its time-lag is very small; unlike the indirect. heated tubes of other types, it takes very little time (a few seconds) to be brought into full operation. www.americanradiohistory.com AIVARTFT Tut' D.rsr, wrr...rc 1 A ..... ,A Radio News for July, 1928 93 I Want To Know (Continued from page 57) AMaltAN EQUALIZER long sections of the core, while the secondary wire should be soldered to each of the wires. After windings are placed on the other long section. the two coils have been completed, the core should The coils should be wound over fiber forms two be assembled. The "L" shaped pieces should be Improves the Volume and inches 'square, so that the form will fit over the butted together from opposite sides, so that they core. The primary coil consists of 600 turns of overlap as shown in the assembled core at Fig. (J. Quality of any Pick-up No. 26 enameled wire, and should he wound 2288B, reversing the arrangement of the pairs in By matching the impedance of the pick -up with the layer-fashion with thin "fish" paper (a thin, tough, alternate layers. When this method is used, the primary of the first audio transformer, the gain in each layer. and insulating paper) over Fifty turns of complete core is solid without much binding, volume and the improvement in tone quality is such wire should be placed in each layer, making a is a simple matter to construct two clamps it very that you will hardly believe that the same instru- total of 12 layers. After the coil has been com- to bind the laminations tightly in place. ment is being used. pleted, it should be carefully taped with friction tape in order to prevent moisture from entering The Choke Coils The AmerTran Equalizer, with its three taps the winding. The two choke coils are identical in construction, will almost exactly match the impedance of The secondary consists of a center -tapped wind- each being wound with 6500 turns of No. 28 D.C.C. any pick -up with the primary of good audio ing supplying a total of 440 volts, with 220 volts wire, on a core of the dimensions shown in Fig. transformers. Designed especially for use with the AmerTran De Luxe 1st. stage, but will work efficiently into the primary of any good transformer. Write for bulletin 1080, fully describing this unique device. Price each -$10.00 AmericanTransformer Co. Transformer Builders for more than 28 Years 142 Emmet St., Newark, N. J.

Specifications of a 25- cycle "B" power unit, suitable or use with a 112- or 171 -type power tube. Large chokes and condensers are required to smooth out rectified .-1.C. of such lote frequency. on each side of the center tap. The complete coil contains 2,400 turns of No. 30 enameled wire, with a tap at the 1,200th turn. This coil should be wound similar to the primary, with 100 turns on ov ro,o .qo each layer; making a total of 24 layers. The fish paper should be used also between the layers of this coil. When the winding is complete, several RADIO layers of fish paper should be placed over it; and CONVENIENCE OUTLETS over this coil is placed the filament winding for Know the greater convenience of a home the power tube, which consists of 28 turns of No. wired for radio. Every connection to 18 enameled wire with a tap at the 14th turn. loud speaker, aerial and ground, A. C. Each of the wires should be brought out through outlet and batteries taken care of in a neat, efficient way. Fit any standard insulating tubing, or a section of insulated flexible switch box. No. Loud Speaker.... $1.00 137 -For Battery Connections. 2.50 136 -For Aerial and Ground 1.00 138 -For A. C. Outlet 1.00 With Oaketlts Plates The core of the power transformer is built up, Rich satin-brown Bakelite plate, as shown, of silicon -steel strips; each alternate with beautiful markings to harmo- nite,at 25 centsextra. See illustra- layer being reversed to bind it together. tion. .4t Your Dealers Q. 2288C. -gap .025 on An air of -inch is provided, YAXLEY MFG. CO. each side of the core, to prevent saturation and Dept. N, 9 So. Clinton St. consequent lowering of the inductance. The di- Chicago, Ill. rect-current resistance of each of these chokes is about 100 ohms, and the inductance is about 20 henries, under the conditions in which they are to be used.

The laminations of these chokes are also cut 1u3/i1an\\ from silicon steel .014inch thick, and each piece Shielded Grid Amplunax is shellacked in the manner described above for USING SHIELDPLATE TUBES TYPE SP122 and Different the These pieces are cut "U "- Absolutely New transformer. The fastest selling kit on the market. Has been acclaimed shaped and straight, for the outer and inner parts "America's Greatest Receiving Set" by Radio Engineers, of the core. In this case, the various laminations Designers, Editors, and Jobbers. Set Builders have been astounded by the revolutionary performance of tame are placed one directly over the other, and no receiver. Write for details or ask your dealer today. staggering is used. The straight pieces can be TYRMAN ELECTRIC CORPORATION assembled and the windings placed directly over 143 West Austin Avenue Chicago, Ill. this part of the core without the use of a fiber spool or other means of support. Several layers of insulating cloth should be wound over the core, and the winding placed directly over this core. RADIO U DE Two fiber washers should be provided, to com- FREE plete the spool for winding the coils; these should RIG NEW 1928 CATALOG -4000 Items be about 3% inches in diameter, with a hole h. Shows the latest A -C circuits, the newest ideas inch wooden In radio at startling low prices. Get the seta square cut in the center. A clamp- and parts you want here. Save money. ing arrangement should be provided for these coils, Tee best ln parts, kits, complete factory - so that the air -gap can be adjusted and fixed. built sets and supplies. Orders filled same Specifications for a 20 -henry choke coil, such as day received. Write for free copy now. regiiired Straight wooden pieces with bolts may be used to are to the 25 -cycle power unit. The Standard discounts to dealers, set builders, agents. air gap is vitally important. hold the laminations tightly in place and, by BarawikCo., 129N.Jeflerson St., Dept.807B, Chicago. U.S.A.

www.americanradiohistory.com 94 Radio News for % :;i\l, 1928

OPPÛRTVN(TY AD -LETS Follow these advertisements every month. Reliable advertisers from all over the country offer their most attractive specials :n these columns. Classified advertising rate twenty -two cents a word for each insertion. Ten per cent discount for 6 issues, 20 per cent discount for 12 issues. Names and addresses must be included at the above rate. Cash should accompany all classified advertisements unless placed by an accredited advertising agency. No advertisements for less than 10 words accepted. Objectionable or misleading advertisements not accepted. Advertisements for the September issue must reach us not later than July 1st. CIRCULATION LARGER THAN THAT OF ANY OTHER RADIO PUBLICATION EXPERIMENTER PUBLISHING CO., INC., 230 Fifth Avenue, New York, N. Y.

Agents Wanted Help Wanted Patent Attorneys (Continued)

Big Money and fast sales. Every owner buys gold National Publisher, needs agents, boys and shops to Patent Sense -Valuable book free. See ?.:,cry's ad, page blh tala for his auto. You charge $1.50; make $1.35. Ten help sell great national magazines. No ins ¡Biwa re- 71. Lacey & Lacey, 631 F. St., Wo: irgton, D. C. eiders daily easy. Write for particulars and free samples. quired. Rig mats, snare(hue work very successful. Established 1869. American Monogram Co.. Dept. 133, East Orange, N. J. Write Agency Division, Experimenter Publishing Co., 230 Fifth Avenue, New York. Patents procured at reasonable rates with time to pay.

Agents-We start you In business and help you suc- 011111111111111n1111116111111n111n11111111161101111111116m1111n1111111111111111111111a18u1m11n11111111111111111116111 1 1111 u Sales negotiated. Staff of registered attorneys and en- ceed. No capital or experience needed. Spare or full tine. gineers. A complete service for inventors. Write for You can earn $50 -$100 weekly. Write Madison Products. particulars. Inventors Service Bureau, Pea 1648, Wash- 560 Broadway, New York. Help Wanted, Instructions ington, D. C.

Guaranteed Genuine Gold Leaf Letters anyone can put on Do You Drive a Car? U. S. Government Chauffeur - store windows. Large profits, enormous demand. Free Carrier lob pays $141 -$175 month. "Dow to Qualify" Patents samples. Metallic Letter Co., 422 N. Clark. Chicago. malted free. Write, Ozment Instruction Bureau, 251, St. Louis, Mo. Inventions Commercialized. Patented rr unpatented. Sell subscriptions to magazines known the world over. ,or,111un111111611,1,11nor,,,,r,,,16n111111111,1111,1,11,11n11111111,111,11ur,,,rr,,,,11,,111111,,,,,,,11,111111111,11,111. n Write Adapt Fisher Mfg. Co., 279 Enright. St. Louis, Mo. Steady monthly income with absolutely no investment re- 1,11111, 111, n, 111, m161n111111111111nn11111n1111111111 ,1111111111111n1,nnnn,m,1111111,,. 011111n111111,1111neunu1vn1 tluired. Hundreds of selling arguments every month. Start Instruction now. Full information sent free. no obligation. Agency Printing, Engraving and Multigraphing Di,isinn, Experimenter Publishing Co.. 230 Fifth Avenue. New York. Learn Chemistry at Home. Dr. T. O'Conor Sloane. Multigraphing, two dollars thou. and. Miscellaneous noted educator and scientific authority. will teach you. Printing. Mayer Rey Corporation, M,mr,,oatb, Illinois. Our home study correspondence course fits you to take a opportunity for entire summer. $5.00 per n16,nr11ru111111,,, 1111111111111,1,,, 111 ,,,nrn11lnrnn, 11,11n1,,,,,,r,n1n1 Wonderful Position as chemist. See our full -page ad on page 07 ,,, hour Saturdays, Sunday's. Sparetiiue. No experience re- of 25 -N this issue. Chemical Institute of .Kew York, 16 E. 30tn quired. Free Booklet. Benson Camerascopc Co., Street, New York City. Radio Delancey. New York. Buy Your B. Power Devices Direct From Factory, Send big outfit free. Cash or Static Filter. Special balanced circuit. Build It your- Agents -Quick sales, profits. self. Complete details, $1.00. Raymond Odorat, Nauvon, for particulars. D. L. & G .1Ifg. S.< , .141 W. Lake, credit. Sales in every honte for our high class line of Alabama. Dept. 9, Chicago. Pure Food Products. Soaps, Perfumes, Toilet Articles,

etc. Write today for money -making plans. American III ::,nul rra: rra, 111, :::1:::::::::11111,1r,,,,,n::: 1111 :1:1:11,11,,,r,1111111,111111nn Prodnets CO., J506 Monmouth. Cincinnati, O. Aluminum cut to order for panels, I.aei-boards, shields,

N1111,1111,1111,111 111 rrr111,,, 111rn111, 111111,11,1111111161,111111oon,. cabinets. White's, 217 Wycoff Ase., Rreetlyn, N. Y. .,, 11111111111111111n11111111,11111111111111111m Male Help Wanted

Books Just o8 the Press. Thoroughly revi.cd; down to the Men -Rig pay working romantic, wealthy South Anterlea. minute with omc1, new material never putdinhed; greatly Fare, expenses paid. South American Service, 14.600 Aima, improved and enlarged; no advance in Detroit, Mich. reite. Fourth Books, Magazines, Art Publications in French, Spanish Edition, "Radio 'theory and Operating, by Mary Tex- English. Photo novelties, samples. lists. etc., 20 cents mina Loomis, President, Loomis Radio College; Member, stamps. Yillarerde Co., Dept. 211, Box 1329, Havana. institute of Radio Engineers. Nearly 900 pages. Over Cuba. 700 Illustrations, beautifully bound in Pesible red craft Miscellaneous leather. Stamped In gold. Complete teat .rod reference ,1,1,1111111111.1,1111111111111,1111111111111,r0100,11111111111111.r,1 r,1111111111n1n,11111111,1nn1,11111111111161601111111111,mm1, book on radio; special chapter on "Aircraft lladio ;' much European material added. especially British. Ever since Business Opportunities Inventions Commercialized. Patented rr ttnputenled. publication of first edition in 1923 Oils bock has been used Write Adapt Fisher Mfg. Co., 278 Farright, St. Louis. klo. as a text by practically all the leading radio schools in the United States and Canada, also many universities, Iechnical colleges and high schools, and all Government Inventions Commercialized. Parented or Unpatented. Save Money at Home. Ynu can build many home neces- radio schools. Recognized as America's standard radio Write Adam Fisher Mfg. Co., 278 Enright, St. Louis, Mo. sities yourself. such as furniture, kitchen utensils, decora- text book. Contains wealth of practical and systematically tive material, etc., thus saving many dollars. All construc- arranged information. Different from ether works on the tional information on hundreds of things given in 116 -page subject; is understandable and interesting; not just page Free Book. Start little \fail Order business, Hadwil. book "How to Make It." Price 50e. Experimenter Pub- after page or dry theory. Fills a long felt want In the 5A -74 Cortlandt Street, N. Y. lishing Co., Inc., 230 Fifth Avenue, New York. line of radio test and reference books. is a library in itself and you should have a copy, if Interested in radio. For sale at nearly all bookstores in United Stales, also in 67 Ways to Increase Income. 96 -page book "Spare - Forma to Cast Lead Soldiers, Indians. Marines. Tran - Shanghai, China; London, England; Melbourne, Australia; contains 67 practical time Money Handbook and complete ners. Anistals. 151 kinds. Send IOc for Illustrated Cata- Welli ngton. New Zealand; Calcutta, India : Honolulu, business. For everyone who plans to operate sparetime logue. A. C. Schicrcte, 1031 72nd St., Brooklyn, N. Y. T. H. ; Manila. P. I.; Yanenuver, B. C. Price $3.50. wants snore money. Price only 50e. Consrad Company. Roy of your bw,kdenler. or send rherk ar money order for Inc., 230 Fifth Avenue, New York. Big Bunch Mail. Year 15e. Catalogues, magazines. pmnzpt delherr to Loomis Publishing l'cu:p,ny, Dept. 7, Washington, D. C. wmwmllmmolmmol..mmunuu1,111111n, nuuuuumunmmminln,,,,lmmmmmuanmmmnmmr Kentucky Agency, Covington, Kentucky.

Chemistry Write about our efficient power devices. NIAMEY ELEC- Musical Instruments TRIC CO., 441 E. Ferry, Buffalo, N. Y. Learn Chemistry at Home. J. T. O'Conar Sloane, Send Be the licensed radio doctor In your community. $7 -$10 noted educator and scientific authority, will teach you. Our Cornetists- Trembenists-Saseehonists- Clarinetists. spare time evenings. Our co- operative plan procures all home study carreopondeece course tits yea to take a position for "Free Pointers." Mention instrument_ V inumo ad an 67 of this School, Buffalo, 70, N. Y. the work you want. Secure franchired territory now. as chemist. See our full-page page Free Booklet. Co- operative Radio Doctors, Dept. N, 131 Issue. Chemical Institute of New York. 16 E. 30th Essex St., Salem, Mass. Street, New York City. a New Radio Logs Bargains. Brand new nationally advertised products. Courses Ralkite AR eliminators, $20.00. l'bUco AB. $27.00, Correspondence Westinghouse Iteetigan, 2 ampere All charger, $9.50. week days and on Entire chain programs at a ;donee Timmons None speaker, $7.95. Cornell R .ks C eliminator, a card board. Needed daily. Time saver. Two 121 of $19.95. school courses sold on repurchase Freshman power amplifier $22.95. Latest type Used correspondence each postpaid for 23 cents. Dullnig Printing Co., San aeroplane cloth speakers. $11.95. ltosch R eliminator, basis. Also rented and es. hanged. Money -hack guarantee. Antonio, Texas. Mountain, $23.95. Write for complete list of bargains. Parts and Catalog tree. (Courses bought). Lee Pisgah, supplies for Edison element rechargeable "R batteries. Alabama. .I. Sled, 834 -A North Randolph. Philadelphia. Pa. r 1111111111 m,11,111 woosm 111m nn nnmmllnlnnr, l r 1,111111111111 n 111 m 1111111111,11111, 111, r, ,1.,1111111111111111111,111111111 Old Money Wanted 01m1 a-,1,1,116111111 r1111,111111111,1rrrrrlrrrrrrrr1r11111n Correspondence Stationery Scenery to Rent $2 to $500 each paid for hundreds of Old or Odd Coins. 200 Lettersheets and 100 envelopes, $1.10. Postpaid. Reel' all old money. it may he very valuable. Send lite for Oberman Company, Box 12268, Chicago. World's Most Beautiful settings for operas, plays, min- New Illustrated Coln Value Rook. 4x6. Guaranteed prices. strels. Amelia Grain, Philadelphia. 1111111111,11n,111111111111111111,161,1111111111111mnn11n1111111111111:1111111..m111111111n11111111111111n1111111111111ll 111111, Get posted. We pay Cash. Clarke Coln Company, 14 Street, LeRoy, N. Y. 00000,r1111111 111000110,m1 1111110016010000,16,00000000000Inn, 1001110 1111, 11, 111111111111111111r11111111111111.11,:111r1111n1n111111. Electricity 1111, 1111111111 ISO 1111111111111111111111111 111111111111111111111111111111111u 1111 1111111111111311111111111111 .111111111111111111111111118 Telegraphy Electric Fun: Seventy stunts, 110 volts, $1. Cooperco, Patent Attorneys Campbell, Calif. Telegraphy -Both Morse and Wireless taught thoroughly. om111111616111 11111111 16,1, mu sin 11 nnnnnml,, 16no161n ,mn16nun16nnu1111111111111111161rrrr1n 11111116161r1o1.111m Pig salaries. Wonderful opportunities. Expenses low, chance to earn pert. School established fifty years. Cata- For Inventors Patents -Send for form "Evidence of Conception" to be log Ore. Dodge's Institute. Caur St., V a i,ureisa, Ind. signed and witnessed. Form. fee schedule. information tree. Inventions Commercialized. Patented or Unpatented. Lancaster and Alhvine, Registered Patent Attorneys in 278 Enright, St. Louis, Mo. United States and Canada, 269 Ouray Bldg.. Washington, Write Adam Fisher Mfg. Co., 1). C. Wanted to Buy

11 n1111111110111116,,,111111111mm11111111111r1111111111111101111111nn111m111,11111111111111 m 111111111111 n 1 m 1111111.1111 m For Sale Full Value Paid for Old Gold, Jewelry. Watches. Dia- Patents-Send drawing or model of your invention for monds, crowns, bridges, dental gold. silver. platinum. gold evanrinotlon and instntrtlons. Advice and booklet tree. or silver ore; magneto points, old false teeth. Packages re- For Sale. Radcola 28 perfect condition with tubes and Highest references. Rest results. Promptness assured. turned if nor offer is not satlsfartory. United States voltmeter, $125.00 cash. No trades rnnsidered. The Watson E. Coleman, Patent Lawyer, 724 9th Street. N.W., Smelting Works (The Old Reliable), 39 So. State 8L, Electric Shop. Wessington Springs, S. Dak. Washington, D. C. Dept. 16, Chicago. Ill.

www.americanradiohistory.com Radio News for July, 1928 95

releasing the bolts, the distance between the two As a Space- Charge -Grid Tube sections of the core can be varied. The 222 tul'e may be used in circuits requiring a tube with a high amplification factor and high Assembly of the Unit mutual conductance, such as resistance -, reactance - After the transformer and the two chokes have or transformer -coupled amplifier circuits. l'or this been constructed, the unit can he completed. The connection, the inner grid is used as a space -charge other apparatus needed for this unit is as fol- grid at a potential positive with respect to the ladio Consoles lows: filament. The normal operating conditions are: One 85 .milliampere gaseous- conduction rectifier Element Supply Voltage A new console designed for tube and I'late "13" +135 -180 RADIOLA MODEL 18 One vacuum-tube socket; Control- (Outer) Grid . -0 -1% or other receivers. either A.C. or D.C. Two 4 -mf. filter condensers, 400 -volt rating; Space -Charge (Inner) Grid "B" +22% One 8 -mf. filter condenser, 400 -volt rating; Filament "A" +3.3 Two 1 -mf. filter condensers, 200 -volt rating; *'l'he negative bias is obtained through a resistor Two 0- to- 500,000 -ohm variable resistors; or potentiometer. One baseboard, 10x12x% inches; Seven binding posts; The plate -supply voltage is not applied directly One insulating strip, 10x2x3-16 inches; to the plate in this case, but to the plate-coupling Wire, plugs, etc., etc. resistor of 100,000 to 250.000 ohms. The apparatus should be laid out with the trans- former at one end, and the filter condensers and choke coils so spaced that the wiring will he as THE "THERMIODYNE" RECEIVER short as possible. The resistors and binding posts ((2290). Mr. A. N. King, Trenton, N. J., writes: can he mounted on an insulating strip fastened to ((,1.) "I would like to obtain the diagram of one end of the baseboard. 1 it is so desired, the the 'Thermiodyne i' 6' receiver. I have one of complete unit can be enclosed in a metal case, these receivers which is not working correctly, and with the binding posts and control panel at the I would like to check the wiring if possible." front. If this is done, it will be possible to (A.) We are printing the diagram of this re- ground the metal case; this will serve to prevent ceiver in this issue; sec Fig. Q. 2290. Unfor- any interaction between the power unit and re- tunately, none of the constructional details or ceiver which might introduce a humming noise. values of the parts employed in this set are avail- The core of the transformer may also be grounded able, as its manufacturers are out of the business; to the metal case and this will tend to increase the but we trust that the diagram may be of assistance stability of the unit's operation. to you in the matter of locating the trouble in your set. Letters from Radio SCREEN -GRID CHARACTERISTICS Constructors Excello Console (2289). Mr. J. M. Kruger. San Francisco, Calif., Model R 43 writes: (Continued from page 91) (Q.) "1 \'ill you publish the operating character- I would like to exchange letters with other istics of the new screen -grid tube? This should builders of broadcast and short -wave sets, especially Receiver compartment is a sliding drawer 29 in x 93.4 in. x 12 Ample room be in. deep. in speaker compartment of interest to a number of radio fans, since those who wind their own coils. for cone speaker and eliminator. Cabinet, walnut this tube is becoming so popular." WALTER IIAWKINS, throughout, with fancy butt walnut veneer doom. (A.) We are printing the data supplied by the Box 50, R. R. No. 1, Wakarusa, bud. .4/ your Dealers, or trifle for complete catalog offull line. Radio Corporation America the of for use with EXCELs.O PRODUCTS CORP. new screen -grid tube, UX 222. "I would feel greatly indebted," writes Arthur 4832 W. 16th St., Cicero, Ill. (Suburb of Chicago) It is designed primarily as a "screen- grid" tube, Ludovichetti, of Villa Anita, Rimini, Italy, "if Pacific Coast represenlatire-Pacific Sales Corpora- 426 Larkin Street, San Calif. for use as a radio -frequency amplifier in circuits you could put me in communication with some tion, Francisco, especially designed to make use of its high ampli- young fellows to exchange ideas." fication and low feed -back capacity between plate and control grid. When used for this purpose, it I wish you could give me the full address of Mr. is not interchangeable with the ordinary three - J. C. Scott, of Plainfield, N. J., as 1 like to cor- element tubes, and cannot be used to replace them respond with radio friends if 1 can. I have in standard This tulle may also be used as letters sets. coming from both coasts each week and it is indeed FrH a "space- charge grid" tube; its extra element be- very interesting to read them, as you get very ing then operated at a positive potential to in- interesting crease mutual points of view. the conductance of the tube. It is "DUCK" useful also for other experimental purposes where BETTELON, R. R. 1, Centerville, Ohio. a double -grid, four -element tube is required. JUNIOR SET BUILDERS Tube Must Be Shielded ESTABLISHED 30 YEARS The tube is provided with the standard UX Editor, RADIO NEws: I am a boy fourteen years of age, and have base and an extra contact at the top of the glass We Have Complete Kits For All Circuits bulb. When mounted in a vertical position, the read your magazine for two years and must say I get much help from it. Recently I built Now appearing or which have appeared tube should be shielded by a metal jacket fitting a in "Radio News" and other publications. closely over the bulb, but having at the top an two -tube set, using the old Armstrong hook-up. aperture, with insulated circumference, and which This puts me right in the DX class and 1 chal- Send for Circuit Booklet lb Catalog insures clearance (not exceeding 1-16-inch) be- lenge any boy my age to construct a two-tube set, tween the metal of the jacket and the metal cap. any hook -up, that will equal mine. I have picked M. & H. Sporting Goods Co. 12 Market St. Phila , Pa. The jacket should extend clown at least to the up stations in thirteen different states: WGY, base, and should he connected to either filament \\'HAM, WCCO, \\'GN, \ \BM!, WLIB, and \ \ -SUI, I use the loud speaker on the Pacific coast terminal of the socket. ,uadfl!14 .t When the tube is used in conjunction with stations and on many Texas stations. I use an *5 °buys storage -battery tubes having five -volt filaments, a aerial 118 feet long and thirty feet high. I have in my set this famous tapped 15 -ohm resistor should he placed in series UX -199s at present and they ate very satisfactory. 'Together, the set has with the negative lead of the screen -grid tube. proved quite a success. Remember my challenge! cabinet(/' In this way, the tube can be operated troni the The Iveyline six -volt supply for the storage battery tubes. NATHANIEL MCKELVEY, Sizes range from 7x18x10 to 7x30x12. Mahogany finish, 55.50 to 604 East First St., Tucson, Arizona. 88.75. Solid Walnut, 86.50 to $10.25. F.O.B. Hickory. When used as a screen -grid radio- frequency Twelve- hour service. Write for Catalog. amplifier, the 222 tube is designed to operate under SOUTHERN TOY COMPANY, MANF'R. HICKORY,N.0 the following normal conditions. I would like to correspond with fellow experi- Element Supply Voltage menters 14 to 15 years of age. I am interested in one, two, three and five -tube sets and will Plate "B" +90 -135 RADIO PANELS exchange notes with any boys out in the \Vest or Screen - (Outer) Grid "B" +45 in foreign countries. BAKELITE -HARD RUBBER 'Control -(Inner) Grid "C" -1.1.5 Cut, drilled, and engraved to order. Send rough Filament "A" +3.3 LEO AUGUST, 510 So. 18th St., Newark, sketch for estimate. Our Complete Catalog on N. J. Panels. Tubes and Rods-all of genuine Bake- This bias may be obtained from a resistor in lite or Hard Rubber- mailed on request. the "A return. -" HIGH POWER IN JAPAN STARRETT MFG. CO. 520 S. GREEN STREET - - The control -grid biasing voltage is given with Reception of Japanese stations in the United CHICAGO respect to the negative side of the Moment. Neither States, Canada, South America and Australia, etc., the plate nor the screen -grid voltage is critical. should be greatly facilitated by the great increase The same battery can be used for both, by using in power of the leading stations. JOAK, Tokio, a tap on the battery. The control -grid bias can (345 meters) and JOIlK, Osaka, (400 meters) have be obtained from a separate dry cell, or may be been increased to 10 kilowatts: and four more sta- obtained automatically when the tube is used with tions of equal power were recently completed. They a 6 -volt supply. This bias is obtained by tapping will take the following wavelengths: JOFK, IIiro- the 15-ohm series resistor at the correct point. In shima, 353 meters; JOGK, Kumamoto, 380 me- B ig New 1928 Catalog -4000 Bargains -Latest A -C is circuits. newest Ideas to radio. at startling low prices. using this tube, it necessary to shield the con- ters; JO11:K, Sendai, 390 meters; JOIK, Sapporo, The sets and parts you want. Save money. Best parts. trol-grid circuit, including the wiring, coils and 361 meters. JOCK, Nagoya (360 meters), and kits, complete factory-built sets, supplies. Orden 1511eá condensers. A grounded metal case should be JODK. Keijo, 345 meters, remain at 1 kilowatt, same day. Write for free copy. Standard discounts to dealers, set builders. aoents. Dept. 807A. used for this purpose. as before. -S. Ifanda. B arawik Co.. 129 N. Jefferson St.. Chicago. U.S.A.

www.americanradiohistory.com 96 Radio News for July, 1928 NEW IMPROVEMENTS

THE UNIVERSAL TRANS- OCEANIC has now been completely redesigned to use the new 222 Screened Grid Tubes in the four stages of radio frequency amplification. The total radio frequency amplification is now approximately 810,000, compared with only 10,000 obtained with the 201A tubes. This allows increased receiving range, greater volume on distant sig- nals and without any loss in selectivity. The detector circuit has been altered to use the new 200A type detector. The audio amplifier has been further improved, a total of four stages being employed, two of these stages in a push -pull system. The push -pull power amplifier will take either two 210 or two 250 power tubes, the most power- ful audio amplifier one could desire. The undistorted output available for the loud speaker is approximately five times greater than a receiver using only one 210 or 250 power tube. The 400 /500 Volt BC Current Sup- ply has been changed to the full wave type, using two 281 rectifier tubes for increased output. Provision has been made to use a Dynamic speaker if de- sired. The addition of the Lentz "A" current supply, having a capacity of 3 amperes at 6 volts, makes the set available for all electric operation.

Present owners of Transoceanics can have the above improvements added to their receivers at a nominal cost, sending the receiver to our factory.

Write for Latest LITERATURE TODAY C. R. LEUTZ, INC. 195 PARK PLACE, ASTORIA NEW YORK

www.americanradiohistory.com mate TATIC Get Clear, Loud Distance Any time of year! Summer, Fall, Winter or Spring-lightning storm, summer heat, or blizzard -it makes little difference; distant stations come in loud and clear, and unspoiled by static when taken out of the ground with t a Rogers Underground Antenna. In all truth, this amazing new device is one of today's greatest forward steps in the perfection of Radio. It actually and positively enables you to dominate Static. The Perfected Invention of DR. J. HARRIS ROGERS ROGERS Dr. Rogers is known the world over for his sensational work of private and governmental nature, in the transmission and reception of ground Í waves. The Rogers Underground Antenna has been perfected for: home use and is manufactured and sold under Dr. Rogers' patents.

,ANTENNA - the Amazing Facts J.H.ROGERS ea When static is present in the air, its strength PATENT Rdis frequently greater than the strength of the desired radio signal. 1.90 J,730 Hence, in the air, your reception is dominated by the noise level. In 1,349,103 - 4 the ground, as Dr. Rogers proved, and as you can prove, there is a lesser amount of static. And when there is static in the ground, it 4 is never equal in strength, to the strength of the desired Radio signal. Therefore, when you use the Rogers Underground Antenna you actu ally reverse the static -signal ratio; you actually dominate static; you positively bring the distant stations in so loud and so clear that what little static there might be in the ground is barely heard, if at all. You'll be amazed when you compare reception obtained with a Rogers Under - ,t ground Antenna to the reception you have been accustomed to. TRY IT ON YOUR SET It costs nothing test the A Rogers Underground Antenna ex- cepting the five minutes time it takes to install it. Just five minutes of your time - that's all you'll be out, if you're not more than pleased. We don't ask you to pay a cent for the Rogers Underground Antenna if you don't find, after exhaus- tive test on your own set, that this great radio improvement is all we claim for it, and all Dr. Rogers proved it to be when he obtained his patents. Send the coupon now. Let us send you ALL the start- ling facts and full particulars of the FREE comparative test we want you to make. Clip the coupon. Send it today. THE UNDERGROUND ANTENNA CO. 4207 -T Cottage Grove Ave. .v .v Chicago, Illinois _- 7raiOfferau , rr- The Undefground Antenna Co., 4207.T Cottage Grove Ave., I CHICAGO, ILL. I CLEAR, STRONG GROUND WAVE I ISend me all the facts on the RogereUnderground Antenna. Also I full particulare of FREE Test Offer and GUARANTEE.

C)heI ' Name I ' Address ' I find rgrDIn ' Town State I lima min mu me ow =me -am - -m .M J jERE is an opportunity for you to be the first in your neighborhood to banish static and have almost perfect ANTEN NA radio reception. Mail this Coupon right now.

www.americanradiohistory.com 4.!.

New and Improved Model

The Ideal Way to convert your present set to an A. C. receiver

Licensed by the No change in tubes or wiring Andrews- Hantrnand Corporation, under patent 1,637,795 and applications New Featuresi-QBetter Value than ever before All the features that made Abox the outstanding Interior changes in construction give assurance success of last year are retained in this new of even longer life and better service. model. The improvements are the result of The reliability and efficiency of the standard untiring research and the experience gained D. C. tubes need not be sacrificed to enjoy the from many thousands of these devices in convenience of true electric operation. Abox actual service. changes 110 -volt 50 to 60 cycle current to For convenience, a receptacle for the "B" hum -free direct current, thus giving true A. C. unit and a control switch is now standard operation. No storage battery is used. equipment. A new design and attractive finish The Abox may also be used to supply cur- add to its trim appearance. rent for the 6 -volt dynamic speaker.

Dealers: Six million radio owners increased efficiency and the convenience vides for a full measure of protection and using storage batteries are of an electric set. The Abox name and co-operation to dealers and jobbers. prospects for Abox. They are thinking reputation are known to a multitude of Write for details. about A. C. conversion. Abox is the set owners. logical purchase for them. It requires no Do not overlook the opportunity of Visit the Abox booth No. 158 at the change in wiring -no external volume selling the idea of A. C. conversion to R. M. A. Trade Show, June 1 1-16, Stevens controls -no change i,i tubes. The set your customers. Hotel, Chicago. Sec the rien' .lbox und retains all its original good qualities plus The Abox merchandising policy pro- other products.

The ulboX Com an 215 North Michigan Avenue, Chicago, Illinois

www.americanradiohistory.com