Short Wave Radio

RADIO'S FOREMOST MAGAZINE RAIN IO NEWS AND litiAltH, 25g SHORT WAVE RADIO

NEW SIGNALGENERATOR

A Publication Devoted to Progress in Radio Service Work Set Building Television Engineering Short Waves Electronics Experiments DX Reception Broadcasting Measurements Amateur Activity Applications www.americanradiohistory.com APPROVED RADIO AX`EY PRODUCTS meet the are designed to . re- most exacting radio SiX made Gontro,s quirements and are 1f1 -_ and last- Vorn Moreha to give reliable ing service. All parts Service fully guaranteed Recel: s Yax1eY Yax1eY Co. Co. ' Manuactutin4 ' of Manuiacturine Division of P.R. Mv.Uory Division Inc üa. tl. Si A. p. R. mmory tndlanapo U.S. A. Indianapolis.

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www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 529

WI L TRAIN YOU AT HOME

IN SPARE TIME FOR A

GOOD RADIO JO B

J. E. SMITH, Pres. National Radio Institute TELLS FREE BOOK MAIL COUPON

Act today for better pay. Act to break away from a low pay, no- future job. Act to get away from having to skimp, scrape to pay your bills. Mail coupon for my free 64 -page book, It tells you how I will train you at home in your spare Good Position Station time to be a Radio Expert; about my training WSMK that has doubled and tripled the pay of many. "1 have a good job, make a nice salary. Many Radio Experts Make $40, $60, $75 a Week and all my success is due to N.R.I. I am Consider these facts -think of the good jobs they stand operator of Station for. Over 17,000,000 Radio sets in use, over 600 broad- WSMK. I highly casting stations, over 40 large manufacturers of Radio recommend the N.R.I. sets, over 3,000 manufacturers of parts, over 100 Police Course. It enabled me Radio SAVE MONEY -LEARN to pass the Govern- Departments equipped, airplanes and airports AT HOME ment examination for Radio equipped. Thousands of ships touching every sea. an operator's license." port of the world are Radio equipped. Over 35,000 Special Equipment Gives You JOHN HAJDUx, Jr., 21 Gerard stores selling sets and parts, about 2,000,000 autos Avenue, Southern Hills, Dayton, Radio equipped and about 20,000,000 unequipped. Loud Practical Experience Ohio. speaker systems wherever people gather, indoors and $18 a Week in Spare Time outdoors. Commercial Radio stations dotting our coast Hold your job. No need to leave home and spend a "Although I am do- lines. Radio a big industry -is grooving bigger fast. A lot of money to be a Radio Expert. I'll train you ing only spare time few hundred $40, $60, $75 a week jobs have grown to quickly and inexpensively right at home in your Radio work, I have thousands. spare time. You don't need a high school or college averaged $13 a week. education. Many of my successful graduates didn't I recommend N.R.I. Get Ready Now finish grade school. My practical 50 -50 method of training. It is cer- for Jobs Like These training -half with lessons, half with Radio equip- tainly a complete A spare or full Course. In a short time time service shop; installing, main- ment -gives you broad practical experience -makes time, it will take a taining, operating -broadcast, aviation, commercial, learning at home easy, fascinating, practical and man, give him a ship, television and police stations. A Radio retail busi- rapid. There is opportunity for you in Radio, Old sound fundamental ness of your own. Installing, maintaining, servicing, jobs are becoming more complicated -many need training in Radio theory, prac- loud speaker systems. A service or sales job with a better trained men. New developments are making tice and design." STEPHEN J. store or jobber. I'll train you for good jobs in new DRAPCHATY, 407 Wunderlich every jobs. Short waves, loud speaker systems, police branch of Radio. Radio, auto Radio, aviation Radio, television Ave., Barberton, Ohio. Radio's - Nets about $50 a Week newest uses are covered by my training. Many Make $5, $10, $15 a Week Extra Here's a field that's growing. It is where you find besides Sales growth that you find o"I' have been getting in Spare Time While Learning opportunity. along fine. I aver- Every neighborhood can use a good part age ten calls a week, time service- which nets me about man. I'll start giving you special instruction material, $50, not counting plans, ideas, the day you enroll, for making money in profits on sales. I spare time. Get my book -read how many of my stu- have serviced almost dents make $200 to $1,000 in their spare time while every make of set and learning. have earned more Stanley Tulk, 2705 Hector Street, Montreal, than I ever expected. Canada, I have I owe my success to writes -"I have been doing so much service work I doubled the N.S.J. and its wonderful haven't had time to study. In two months, I made about Course." BERNARD COSTA, $200 in spare time." Lloyd V. Sternberg, 217 Fourth 150 Franklin St Brooklyn, New Avenue, Willmar, Minn., tells me -"I earned enough in and York. spare time to pay for my Course. In one month I tripled earned $125 in spare time." Yes, my training pays! FREE: Your Money Back if Not Satisfied the salaries Radio Servicing Tips I'll make this agreement with you. If you are not en- Let me PROVE that my Course is tirely satisfied with my Lesson and Instruction Service clear, easy to understand and fas- when you finish, I'll refund your tuition. of many cinating to study. Send the coupon for a free lesson, "Tenable Shoot- Find Out What Radio Offers ing in D.C., A.C., and Battery Sets." This interesting lesson Mail the coupon. My book of information on gives 132 ways to correct common Radio's spare time and full time opportunities Radio troubles. I am willing to is free to any ambitious fellow over 15. Read send this book to prove that you what Radio offers you. Read about the train- too can master Radio-lust as ing I offer you. Read letters from graduates thousands of other fellows have what they are doing and snaking. - J. E. SMITH, President done. Many of them, without even There's no Radio a grammar school education, and obligation. Mail coupon in an envelope or National Institute, Department SCR no Radio or technical experience, paste it on a postal card -NOW. Washington, D. C. have become Radio experts and now earn two or three times their for- Dear dere lliail the coupon now. J. E. SMITH, President llr. Smith: I want to take advantage of your Spe- pay. cial Offer. Send me your two books, "Trouble Shooting in National Radio Institute, Dept. 5CR D.C., A.C., and Battery Sets" and "Rich Rewards in Radio." I understand this does not obligate me. (Please Washington, D. C. plainly.) print

NAME AGE BETTER PAY ADDRESS Wa to CITY TheTesfied Y STATE i f f l

www.americanradiohistory.com Edited by LAURENCE M. COCKADAY

S. GORDON TAYLOR WILLIAM C. DORF Vol. XVI Managing Editor Associate Tech. Editor No. 9 JOHN M. BORST SAMUEL KAUFMAN Technical Editor Broadcast Editor

EVERETT M. WALKER JOSEPH F. ODENBACH Associate Editor Art Editor March, 1935

Reading Guide 1 Dots and Dashes 532 2 Radio Facts and Oddities 534 By H. T. Elmo to this Issue 3 Radio Set Building 535 Editorial As a matter of convenience for those hav- 4 Home -Built "High- Fidelity" Receiver 536 ing specialized interests in the radio field, By John M. Borst the following lists the articles and features 5 in this issue, classified under 14 heads. The How to Build the Browning '35 538 numbers correspond with the article numbers By Glenn H. Browning in the Table of Contents on this page: 6 Designing Saturable Reactors 540 By .Boron Brozon Amateurs -6, 8, 11, 12, 13, 15, 16, 23, 26. J. Broadcast Fans -4, 5, 7, 10, 12, 21, 22, 23, 7 The "All- Star" Junior All -Wave Receiver 542 24, 26. By Laurence M. Cockaday Dealers-3, 5, 7, 15, 16, 17, 23, 25, 26. 8 Experiments with Multiple Regeneration 544 Designers -6, 8, 16, 18, 19, 23, 26. By J. Plebanski DX Fans -5, 7, 8, 9, 10, 12, 13, 14, 15, 21, 9 Capt. Hall's Short -Wave Page 546 22, 23, 26. By Capt. Horace L. Hall Engineers -6, 16, 18, 19, 23, 26. 10 13-550 Meter Superheterodyne Receiver 547 Experimenters -4, 5, 6, 7, 8, 11, 12, 13, 15, By S. Gordon. Taylor 16, 18, 21, 22, 23, 25, 26, 27. 11 The "Ham" Shack 548 Manufacturers-16, 23, 26. By Everett M. Walker Operators -11, 23, 26, 28. 12 Short -Wave Converter Design 549 Servicemen -4, 5, 7, 12, 14, 15, 16, 17, 19, By S. Gordon Taylor 20, 23, 25, 26, 27. 13 Improving Your Regenerative Receiver 549 Set Builders-3, 4, 5, 7, 8, 12, 13, 16, 19, By Robert Hertzberg 23, 25, 26. 14 The DX Corner for Short Waves 550 Short -Wave Fans -5, 7, 9, 10, 12, 13, 14, By Laurence M. Cockaday 15, 23, 26. 15 World Short -Wave -Table Students 8, 13, 18, 19, 20, 23, 25, 26, 27. Time 553 -6, Compiled by The Editors Technicians -4, 5, 7, 13, 17, 20, 23, 25, 26. 16 New Type of Carbon Resistor 556 17 A New Rack-and -Panel Amplifier (Part 2) 557 By B. J. Montyn ext cnConth 18 First Aid to Inventors (Part 5) 558 By E. E. Free, Phd. The April issue will provide a wealth of 19 An All -Wave Signal Generator (Part 2) 560 helpful information for the short -wave fan By John H. Potts on receiver design and construction, shortwave antennas, new commercial receivers, a 20 Radio in Aircraft (Part 4) 562 new world- distance map, a complete wave- By Henry 11'. Roberts length- frequency conversion chart, etc., in 21 Sunset to Sunrise with Foreign DX (Part 2) 563 addition to the regular Short -Wave DX By R. H. Tomlinson Corner and World -Wide Short -Wave Time 22 The DX Corner for the Broadcast Band 564 Table. By S. Gordon Taylor For the Experimenter: Short -wave coil 23 The Technical Review design, information on inventions and pat- 568 ents, and applications of the new 12A7 tube. 24 Backstage in Broadcasting 570 For the Amateur: A new "Ham" crystal 25 The Service Bench 572 superheterodyne receiver, the "Ham" shack. 26 What's New in Radio 574 For the Serviceman: Profits in group hear- 27 Students' Radio Physics Course ing aids, controlled high- fidelity, interference 576 eliminating antennas, new receivers, etc. 28 ORD P 578

Published Monthly by Teck Publications, Inc., Washington and South Avenues, Dunellen, N. J. Lee Ellmaker EDITORIAL AND EXECUTIVE OFFICES and Treas. 461 AVENUE, NEW YORK CITY, N. Y. President EIGHTH 25c a Copy, $2.50 a year, B. Holcepl Entered as second class matter at the Post Office at Dunellen, $3.00 in Canada, $3.50 in Secretary N. J., under the act of March 3, 1879. Copyright, 1935, by Teck Publications, Inc. in U. S. and Canada. All rights Foreign Countries. Sub- H. D. Crippen W. P. Jeffery reserved. scribers are notified Management Registration of title of this publication as a trade mark applied that Advertising for in United States Patent Office. Printed in the United States change of address must reach Virgil Malcher of America. The contents of this magazine must not be repro- us five weeks in advance of 205 W. Wacker Dr., Chicago duced without permission. We cannot be responsible for lost the next date of issue. Wcstcrn Representative manuscripts, although every care is taken for their safety. 530

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 531 'LL LET MASTERPIECE OWNERS TELL YOU THE STORY! CERTAINLY NO ONE KNOWS BETTER WHETHER THIS IS ACTUALLY THE FINEST RADIO OF ALL TIME None can contradict that "the proof of the pudding They've all owned a great many receivers. They is in the eating." So, the value of a particular radio selected the MASTERPIECE after long experience, may well be gauged by what a number of owners get thorough investigation, test and comparison. They from it. The owners who report below know radio. expected much. You judge whether they got it! Ifr]rurdn cu, 4 Quiet Operation Reaches Out- Easy to Tune "The first thing that strikes a prospect is the quiet "The tone is best I have heard (including the so operation, for with a carrier above noise level. the called hi- fidelity sets) ...The ability of the MASTER- stations ear can detect no indication of action when no PIECE to reach out and pull in foreign with tone and hold them is beyond signal is being received ... the next is the clear and such volume and Ine...also very quiet on short waves. The band - brilliant tone. " -F. J. Reese. 78 Main St., Hacketts- spread dial is great and makes short wave stations town, New Jersey. easier to tune than long waves on some sets. - Tuned in almost everything including Japan." - Perfect Reproduction Gene Morris, 5022 Bienville, New Orleans, Louisiana. time and "Since 1,119. I have spent endless energy, money in my search for perfect mechanical repro- 10 K.C. Selectivity Plus! duction of sound.-For several years, I have been MASTERPIECE III to speak of mine as a radio, because it. Now, at last you have pro- "Impossible rather hopeless about With new Watch Dial -new Bandspread- it is not all like the instruments we have come to with PERFECT at vided PERFECT RECEPTION doss A Prime Audio - Single Channel know as radios. -Music reproduced is smooth. REPRODUCTION.-Music is my profession and soothing, fully rounded, has great depth and you what it Selectivity - Fractional Microvolt Sensi- pleasure ... I am sure you cannot know tivity, controllable for all locations and hear all the treble and bass notes. -None can means to me to have here at my command the match the low noise level and wonderful sensitivity. conditions. local symphony concerts of the world; flooding the house, Selectivity? Only one I've found to cut out antenna is mile away! and volume, sans distortion, sans apology, (toler- \VBZ, 990 KC, whose 34' in full 1000 KC without with straight line amplification Stands the "Third Degree" bring in WOC, Des Moines, ances, compromises; cross talk. " -Wm. L. Riley, Jr., to the highest slightest bit of curve. from the 32 foot pedal octave of Expert Scientists, Too Belmont Hotel, Springfield, Mass. violin harmonics. and beyond; consequently with realism. full dynamic values and all the That this is no ordinary radio is eloquently absolute widespread choice and unstinted 10,000 Miles -No Noise! thrilling dramatic qualities which arc so sadly proven by its praise by acknowledged experts. Major Glen, foreign sta- flattened out in ordinary reception. " -Horace "Getting most consistent reception of British scientist, after testing 47 of the world's every day, Admiral Middleton. The Firs, South Milhrook, New York. tions-England and Germany "best" allwave receivers chose the MASTER- Byrd direct, Australia clear as a bell with absolutely PIECE alone as capable for his exacting re- no noise. Impossible to talk merits of the MAS- World -Wide Reception search in transmission phenomena . . . Dr. TERPIECE-it just has to be demonstrated." - Wm. C. Bostwick of Ithaca, N. Y., after ex- Jas. F. Overton, 924 Pizer Ave., Houston, Texas "For workmanship, material. tone and reproduction haustive tests brands the MASTERPIECE as the best by far" (He now of programs. it is ... incomparable . . . Paramount sound techni- Speaks includes a short wave reception log showing all cians sought a receiver proficient enough to An Ohioan North Americans, Bolivia, Paris, Berlin, London, produce performance results so startling as "I put up my RCA antenna and tried for distant chose Canada, Japan, Argentina, Madrid, Portugal, to be NEWS. Thus they MASTERPIECE stations. Picked up from West Coast: KHQ, KGW, Brazil, Cuba, Colombia, III for Bing Crosby and Richard Arlen who KFI, KPO, XEBC, KGO, KGA, KNX, KEE Switzerland, Australia, DX reception records. Africa, Russia, Vatican and have now smashed all (7797 KC) ... very good this time of year. On Ecuador, Venezuela, Columbia Broadcasting System uses DJD, GSD, identified, and observes short waves my quick log covers: many others not definitely MASTERPIECE III in their New York Studios GSB, PRF5, COH, TIEP, Oregon') H. Bohn, CJRX, EAQ, IRM, that "this is good for -F. to bring Europe into the heart of New York's PRADO, HJ IABB, CJRO, YV3BC, VE9GW, GSA, Box 542, Klamath Falls, Oregon. business district . . . Chosen as a result of DJC, COC, XEBT. "-H. G. Eichorst, 2535 Burnet comparative tests made by Navy officers, Ave., Cincinnati. Ohio. South Pole in Colorado MASTERPIECE III now serves aboard Uncle Sam's flagship U. S. S. Pennyslvania, most In Peruvian Desert "Upon my return from a meeting last night, Mrs. completely radio equipped ship in the U. S. Finch reported receiving KFZ (Little America) Navy ... In all radio history, no receivers were "It is a splendid radio and the entertainment re- as made by direct ... Reception clear and free from background ever given such gruelling tests that ceived over it, as well as world news, is a source of Admiral Byrd's radio adviser in selecting the and my wife, here on a noise ... England, Germany and Spain are daily keen enjoyment to me MASTERPIECE for use on the greatest of all desert.' -John D. Hall, Negritos, occurrences with us to amazement of our friends. - Peruvian Antarctic expeditions ... Mr. Cyril Mockridge, Peru, S. A. One former radio dealer remarked 'the first one I famous musical authority, creator of many ever heard here that could deliver short wave immortal musical backgrounds for Fox Films, AVC reception which didn't sound like a bucket of coal selected MASTERPIECE for its musical supe- No Fading -Real falling downstairs!'-I am mildly insane over the riority ... Can you go wrong in following the "No trick to tune GSB, GSA, DJC, DJB, FYA, set."- Donald F. Finch, 764 Gilpin St., Denver, lead of these known authorities, when you 2R0 and EAQ with tremendous volume almost receiver? Why deny yourself Colorado. select your allwave every day, no fading. Heard Byrd direct several this kind of radio performance? occasions. Broadcast dial is a peach -KFI, KPO, Foreigners Clear as Locals KSL and others too numerous to mention come in like locals in the evening." -Louis Ilausottcr, for its Mo. "I am greatly pleased with my new receiver 1 SOOA Destrahan St., St. Louis, fine tone and selectivity. -Foreign stations are free from distortion, no fading and as clear as local broadcast." -Henry D. Hannah, Mansfield, Conn. 10 DAY FREE TRIAL Send now for the "Blue Book of Radio" and abun- 1---MAIL COUPON-- the finest radio Alabama Casts Its Vote dant proof that this is really of all SILVER, INC. how I let the receiver itself do its own McMURDO time. Learn A. "I have now had my MASTERPIECE 11I about selling job with you, through a 10 days' test right 3352C N. Paulina Street, Chicago, U.S. two months and although I am using a makeshift in your own home. Also a Questionnaire covering Send me full particulars and specifications 30-foot, one wire antenna, 1 am getting any and your location for advice as to proper installation. of MASTERPIECE Ill. everything."-J. M. Reed, Bay Minette, Alabama. All is FREE, no obligation. Mail the coupon today! Name.. MSMURDO SILVER, INC. Street Town_. .. State.. 3352C No. Paulina Street. Chicago, U. S. A.

www.americanradiohistory.com 532 RADIO NEWS FOR MARCH, 1935

DOTS .. and LIMB NM DASHES PACIFIC TELEPHONE LINK Short The three pictures above illustrate the but Interest- new Tokio -Dixon Trans -Pacific radio- ing Items from the telephone recently inaugurated. At Month's Radio News left is the speech "garbler" panel for insuring secrecy. Center: The receiv- the World Over ing station at Komuro, and at right Sales of Radio Sets Attain All - Chiduko Kashiwagi, the Japanese tele- Time High During 1934 phone operator who will handle all calls office. In another demonstration Dr. C. C. NEW YORK-After fifteen years of Clark, in charge of the Science Department, brain of a cat. They made a noise resem- radio broadcasting we find this era of ether spoke to the class from his home on a bling machine -gun fire. The experiment transmission so deeply entrenched in all the similar set. The short -wave instruments was made by Dr. Detlev W. Bronk, Direc- ramifications of modern life that few pause employed were National transceivers. tor of the Eldridge Reeves Johnson Foun- to realize that it was only in 1919 that the dation for Medical Physics at the U. of P. first broadcasting station started to operate. Marconi and Alexanderson Standard vacuum -tube amplifiers were From even the last few years of economic Honored used. difficulties the industry has emerged with Two Great American interest in its products at a new high pitch SCHENECTADY, NEW YORK - Dr. and manufacturers have proved their versa- E. F. W. Alexanderson, Consulting Engi- Companies Combined tility and resourcefulness by rising above neer of General Electric Company, noted the adverse circumstances encountered. CAMDEN, NEW JERSEY-Consolida- for his contributions to radio, and the tion of the RCA Radiotron Company with During the past year there was an almost famous inventor, Senatore Marconi, have uninterrupted month -to -month gain in RCA Victor Company into a single organ- been elected to membership in the Royal ization to be known as the RCA Manu- sales, with the demand for all -wave re- Academy of Science of Sweden. ceivers impervious to the usual period of facturing Company, Inc., was announced summer dullness. Automobile, motorboat Doctors Hear Nervous System recently by Mr. E. T. Cunningham, Presi- and portable sets tended to help create this Broadcast dent of the new company. situation and the introduction of all -wave sets at prices within the reach of the mul- NEW YORK -Three hundred astonished President's Cabinet Makes titude has been one of the outstanding physicians attending the annual meeting of New Record contributions. Radio sales for the whole the Association for Research in Nervous and Mental Diseases held here recently WASHINGTON, D. C. -The Roosevelt country averaged 40 percent larger than administration made new records in broad- for 1933 bringing total sales to 5,350,000 heard sounds amplified from the nervous impulses sent out from the lungs to the casting in 1934 according to the NBC. The for 1934 as compared to the previous peak President made 23 broadcasts during that of 4,438,000 for 1929. ULTRA SHORT WAVES IN year. The Vice -President made one radio EDUCATION speech and each member of the Cabinet Ultra Short Waves Help Studies In recent experiments at New York spoke at least once, or a total of 78 ap- NEW YORK- Recent experiments with University, Dr. C. C. Clark addressed pearances on the air. Postmaster General Farley spoke 22 times during this 5 -meter transceivers made at the School classes holding a two -way conversa- period. of Commerce, New York University, tion and lecture between his home and demonstrated the feasibility of using the classroom in the School of Com- Long Distance Records Broken ultra- short -wave sets for inter -classroom merce. Photo at left shows the scene CHATHAM, MASSACHUSETTS - communication for lectures and two -way in the classroom. Photo at right shows Spoken greetings flashed across 8905 miles communications. During recent demonstra- Dr. Clark reading lecture. (Another of space last week when a British mail tions Assistant Dean Edward Kilduff lec- photo appears in the DX Corner for pilot flying over Persia exchanged greet - tured to assembled classes direct from his Short Waves.) (Continued on page 568)

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935

TI-16 ONE MAN IN 100 H CAN SERVICE MODGRN RADIO EC .. :

RADIO SERVICE WO12.IC. NOW OFFERS GREATEST OPPORTLINITIES SINCE RADIO BEGAN Radical changes have taken place in radio receiver design during the past year. Circuits and construction are very different from the receivers with which the radio service industry has had its greatest experience. Even more sensational developments with further complications are coming next season. Who will service these receivers? Cer- tainly not the "old timer" who knows nothing about modern receivers! He THIS CIRCUIT ANALYZER can't do it. That is why, right now, AND POINT -TO -POINT for reliable RESISTANCE TESTER. there is an urgent demand INCLUDED service men with up -to -the- minute knowl- F/2EE- OF EXTRA CHARGE edge of modern radio receivers. Such .4- >LSc3r men can step right out and earn up to FOUR- LARGE KITS $3 an hour doing nothing but pleasant Of HOME PRACTICE service work in the better homes around EQUIPMENT town. No Past Experience Needed TNIS counts for little IT'S JUST AS SIMIL-I AS Past experience actually NOW THE SET at this time, because the swift changes in OF COURSE SOUNDS GREA --f (MADE - $,18 TWO OTHER MEN ! HAVE TRIEDTO' TO -DAY receiver construction have made knowl- I CAN FIX IT BUT THERE'S NOBODY --.. t equipment practically useless. COULDNT 00 IT edge of old FIX IV_ ELSE IN TOWN },,1Ì know one tube Even though you may not CAN FIX WHO,- i/ from another today . . . still, you can THESE NEW -- take R.T.A. training and make more SETS money servicing modern radios than most of the "old timers" are making. R.T.A. graduates are doing it every day. Many of them are making more money 'i/t as R.T.A. Certified Radio Technicians R.T.A. Membership Keeps You Ahead of Competition With your course of training, and without extra cost, you get a valuable lifetime lives ! than they ever made in their before membership in R.T.A. This gives you a big advantage over ordinary service men Be An R. T. A. Man and You'll Be . because we constantly furnish advanced information to our members ... informa- the One Man in 1000 tion that puts money in your pocket while the other fellow is stumbling around in R.T.A. training will equip you to give fast, the dark. complete service to any radio receiver built. To Start You Making Money Right Away The jobs that puzzle and sometimes baffle the Quickly following your enrollment for training with R.T.A. you get, without extra usual service man will be simple as "A.B.C." cost, the R.T.A. Set Analyzer and Resistance Tester ... the handiest piece of portable to you . . . when you become an R.T.A. Cer- service equipment ever de- tified Radio Technician. It is very possible that vised. Instantly helps you SEND COUPON you will be the only service man in your local- locate the trouble in any A. G. Mohaupt, Engineer ity able to quickly diagnose and quickly repair type of receiver, old or Radio Training Assn. of America the new types of radio receivers. Be the one new, and shows you pre- Dept. RN -53, 4513 Ravenswood Ave., Chicago, III. man in 1000! You can. cisely what to do about it. Dear. Mr. Mohaupt: Please send me your free book of facts about radio opportunities and how I can make big money Quickly. Also tell me how I can obtain your Set Analyzer and four big experi- RADIO TRAINING mental outfits-FREE OF EXTRA CHARGE. Name ASSOCIATION of AMERICA Address.-.. City State 4513 Ravenswood Avenue CHICAGO, ILLINOIS J

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www.americanradiohistory.com March, 1935 7CADIO SET -BUILDING (The Editor-To You) Most Americans really enjoy doing things with their own hands and co- ordinating their workmanship with their own individual brain power. That is why Americans have always been interested in radio construction. Recently set -building has been growing in popularity, in leaps and bounds; at least, that is how it is with RADIO NEWS readers

SET building as a hobby seems to have engaged the their attention. They want the latest development in interest of more radio fans recently than at any circuits and in construction, incorporating the new multi- time since the popular home -construction days of purpose tubes, automatic volume control, beat -frequency 1924. People, young and old, are turning to set building oscillators, band -pass filters, distortionless demodulators at home to enable them to listen in to short -wave trans- and amplifiers. They want a simple but good -quality missions from all over the world. It is true that the output circuit. They require the use of good loudspeakers increase of activity on the short waves has had a lot to to give good reproduction. They want the latest and do with this revival of interest, but it is also true that most efficient methods of noise reduction, along with good people want to build not only short -wave sets, but sets sensitivity, in their antenna equipment. that will bring in the regular broadcast -band trans- Realizing these needs of a large number of radio ex- missions. perimenters who have been "steady customers" in the Today's increasing group of set builders are better in- more experienced set building field as well as the thou- formed than they were ten years ago. They do not build sands of new recruits who have been turning to set build- any old circuit that comes along, but seem to have ing during the past year, RADIO NEWS has specialized learned how to tell when a really good set is brought to in the better designs (Continued on page 567) THE THRILL THAT COMES FROM TUNING IN DISTANT STATIONS Some experimenters go in for 1, 2 or 3 -tube sets exclusively. Others have felt the urge to build and operate larger sets up to 4, 5, 6 and even 7 or 8 tubes. But whether it be 2 tubes or 10, the accomplishment lies in getting results and in tuning in hard -to -get stations on the other side of the world with an instrument you have built with your own hands

535

www.americanradiohistory.com 536 RADIO NEWS FOR MARCH, 1935 A HOME BUILT RECEIVER "HIGH -FI DELITY" The receiver illustrated and described RADIO NEWS, whose primary interest of receiving apparatus for the lifelike John M.

Above then, are the requirements the former. After several others were tried receiver had to meet. Let us see now this one was found to give the most how the problem was solved. For high even response at frequencies between fidelity it is undesirable to have too much 550 and 1500 kc. selectivity, and therefore no attempt The triode section of the 55 tube was made reach LOUDSPEAKER MOUNTING to any greater degree serves as the first audio amplifier. It of selectivity than was necessary for works at a fixed The speaker is bias and is coupled to mounted on a small adequate separation of "local" stations. the output stage wooden base which is bolted to a rub- by an Amertran D21 ber pad. This pad Thus, a superheterodyne was out of the input transformer. The transformer in turn is clamped question, to the top of the large wooden block. since even the broadest of its primary does not carry the plate cur- kind cut sidebands. Also, the fre- rent; a shunt feed arrangement being quency conversion causes some noise. employed. Note that INDIVIDUALS differ in their idea of the cathode cir- So it was decided to employ a t.r.f. cuit is bypassed by a 10 the "perfect" receiver. Some want mfd condenser circuit, a diode detector and as few and that resistance -capacity filters are the best of quality and never listen audio stages possible to anything as with an output employed in grid and plate circuit. farther away than 50 miles stage of Class A triodes in while others push -pull When the phonograph is used, it is want to receive stations (See Figure 1) The r.f. section consists necessary from the Antipodes regardless to cut in an extra audio of qual- of three tuned stages employing the 58 stage. This is ity. The owner, builder accomplished by SW2 and designer of type tubes. Sensitivity is controlled (Figure 1). The switch the set illustrated here is Mr. W. W. is a four -pole- both in the antenna and in the cathode double -throw Yaxley switch. Kuhlman of Woodcliff, N. J. It was It changes circuit of the first two stages. It is es- the input and output of the 56 stage Mr. Kuhlmann's idea to build a receiver sential that a good potentiometer be and also turns on the 56 filament. which would have the best tone quality There used here in order to avoid noise. All is then a second switch to change possible within a price range of ap- over plate, screen and cathode circuits are from radio to phonograph (SW1). Since proximately $100. Incidental require- filtered. ments the volume of radio programs is regu- were attractive appearance and Since the diode detector places lated by ease of quite a control in the r.f. amplifier, a operation. a load on the circuit, the selectivity second volume Most people of control is incorporated do not like to get up out this stage is usually so poor that an un- in this second a.f. of a comfortable chair stage. With this sys- to change the tuned circuit can logically be employed. tem of switches it is possible tuning of the receiver or to add one adjust the The three previous stages give satisfac- a.f. stage when receiving radio programs volume control. Although it is possible tory selectivity to receive the best local -by moving SW2 only -but this is not to have a remote control conveniently station and more was not needed. placed, required. this system has its complica- There have been receivers which used The output tions. stage is quite conven- It was therefore decided to sepa- untuned stages and some of the trans- tional except rate the loudspeaker that the bias resistor is from the set, to formers can still be picked up. The adjustable so place the receiver one can set it for mini- where it would be transformer employed in this receiver mum harmonic distortion. The convenient to tune, and locate the loud output was a DeForest D2 iron core r.f. trans - transformer is a Jensen, the one speaker where it sounded best. This that arrangement also eliminates one source REAR VIEW OF RECEIVER of microphonism. MOUNTING DETAILS DETAIL OF BAFFLE Figure 3. Speaker is mounted on a rubber pad, which in turn is bolted to Figure 2. The baffle is made of four a wooden block, thereby insulating pieces of the Celotex cemented together. speaker from the cabinet. Spaces be- The edge of the center hole is beveled, tween speaker, pad and improving the wood block appearance. (See pho- are shown exaggerated for the sake of tograph) clarity

BOLT TH RU SPEAKER BASE, WOOD BLOCK, RUBBER PAD AND SPEAKER STEEL STRIP WOOD BLOCK STEEL RUBBER STRIP_ I..Iq AR THICK

GROOVE IN BLOCK

BOLT HOLDING RUBBER PAD CABINET TO WOOD BLOCK FLOOR AND TO CABINET FIG. 3

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 537 DESIGNED FOR RECEP' l'IO\ here is one constructed by a reader of in radio experimentation is the design reproduction of local radio programs Borst

comes with the speaker. It is mounted order to effectively inside the set, and 20 foot leads run to hear low notes the A the voice coil. size of the baffle RECEIVER -AMPLIFIER CHASSIS The power pack is also quite conven- would have to be tional. The power transformer is an large, / wavelength Amertran WA321, the chokes are across, and this would mean 11 feet at a square box but the opening at the Thordarson and the condensers are 50 cycles. The best solution seemed to back is much wider than at the front. made by Aerovox. However, other use some kind of a cabinet, which makes The speaker itself was bolted to a makes of good quality can be substi- it possible to have more baffle area in piece of wood having the proper slant to tuted. less space, but precautions must be fit against °the inclined baffle. This wood The radio cabinet was made to order taken to avoid cabinet resonance. The rests on a sponge rubber mat which in by a cabinet maker but the panel was construction of this baffle and speaker turn is fastened to the wooden blocks made by Mr. Kuhlmann himself and is cabinet are unique and contribute a below. The speaker itself is thereby stained a dark mahogany. great deal to the excellent quality. mechanically insulated from the cab- The construction of the set itself as Cabinet resonance, so Mr. Kuhlmann inet. This is shown in Figure 3. shown in the photographs includes some reasoned, is caused by sound reflecting The cabinet was made to order by a noteworthy ideas. The chassis carries from parallel surfaces or from double cabinet maker; it is constructed of ap- a pair of steel brackets on top. These reflections at right -angled surfaces. The proximately 3A-inch oak. It is 48 inches serve as a stand when the set is turned idea then is to avoid right angles and wide at the rear, 34 inches wide in front, upside down so that one can work on parallel surfaces in the cabinet. Fur- 32/ inches high and 18 inches deep. it without hunting for supports to fit thermore, the speaker and the baffle had The special baffle was cut to order and the irregular height of various parts to be mounted in such a way as to pre- cemented by the dealer in celotex. The above the chassis. vent the transmission of vibration from cabinet was finished in black and the It will be noticed in the rear view speaker to cabinet. celotex was given a coat of gold paint. that the power tubes and rectifier hang Figures 2, 3 and the photographs show The writer went to Mr. Kuhlmann's upside down. This was done to keep how this was accomplished. The speaker home to listen to this set. Several pro- the heat of the tubes away from the has been mounted in an inclined posi- grams on the larger local stations were electrolytic condensers and yet have the tion and the baffle consists of four tuned in and also programs on the connections short. pieces of celotex, cemented together. smaller stations. It was found that the The speaker is a Jensen type M -10 The odd angles are clearly shown in speaker will reproduce at full volume auditorium speaker with an a.c. field. Figure 2 and in the illustrations. This without a trace of cabinet resonance. It This speaker had to be supplied with a celotex baffle was placed into a wooden has apparently a wide frequency range, baffle large enough and yet reasonably cabinet, but insulated from it by strips for the lower bass -viol notes and organ good looking. It is well known that in of sponge rubber. The cabinet is not notes -those (Continued on page 567)

M.25 FD. 58 58 58 T4 55 56 45 Ti T2

O Ijrá 5O0,000 HMS X X { ,{ÇX X Y MFD MFD ÓÓ.4 500,00 0 20,000 300 20,000 600 OHMS OHMS OHM' OHMS 5 OHMS OHMS R.F. C. RFC -,2 { 401 M FD. MFD. s 2 5 MFD. a MED. 30,000 i RADIO- 3 OHMS , 'sw{ {00,0 2 {0,000 20,000 50,000 MED. .02 .' i OHMS OHMS OHMS OHMS MFD PROUO 20,000 0 NOT USED. {O {O M ED. ' MED. 00 111 111 111 20 FEET TO LSO LOUDSPEAKER TO 84 4PDT SWITCH ISOLATE 56 TUBE. 5Z3 A 7 +13.5 1 MEG. SW. '-20,000 G MFD EACH OHMS O 2 MFD. 45'S PLATE ;PICK -UP Y ={000 ',CURRENT LEADS X OHMS JACK.

{ 20 V. TO 60^, LOUDSP'KER 1_ 20,000 50Q000 X FIG. 4 OHMS OHMS

www.americanradiohistory.com 538 RADIO NEws FOR MARCH, 1935 The "HOW TO BROWNING

(By Glenn H. Browning)

Here is the latest creation of the Drake receiver. A brand new set principles. The Editors feel that in forming a distinct service to all Radio FRONT PANEL LAYOUT Post This view of the Browning 35 shows the neat and efficient tening Observers to whom high layout of the front panel, with a new type tuning dial that should prove to be a DX'er's paradise Part

AFEW years ago all -wave receivers THE writer has, for the last year, noted from the wiring diagram in Figure which were designed for maximum felt that there was a demand for 1 a stage of tuned -radio -frequency am- efficiency all used plug -in coils. Today, an all -wave kit so designed that plification precedes the detector on all no wave selec- however, equal efficiency may be obtained the average set builder would have -bands, thus giving added easily image frequen- by carefully designed switching arrange- difficulty in putting it together tivity which eliminates ments, and in the years to come the and in obtaining good results. It is also cies and harmonics, as well as materi- re- writer ventures to predict that coil switch- believed that most experimenters and alIy adding to the sensitivity of the welcome an efficient coil - ceiver. This will be especially appre- is the only method that will be used amateurs will ing unit. With that object ciated by those who have used short- where more than one band is frequently switching tuning in view was started on the set to wave receivers consisting of only a The reason work used in the same receiver. be described in this series of articles. tuned detector and oscillator. for this is obvious. In a plug -in arrange- It is not within the scope of this article In order to obtain greater selectivity ment there are two wiping contacts for to give the details of the design difficul- and at the same time finer quality, a each coil, while in coil switching one ties which were encountered. It suf- band -pass "filter" intermediate stage is contact per coil is all that has to be fices to say that all were finally over- used between the 2A7 and the 58. This changed. True, the other coils that are come and that the final model is one band -pass filter consists essentially of not being used at that time should be that I can give my honest O. K. three separate tuned circuits. Each of short -circuited, but advance switch de- The superheterodyne circuit I have the three inductances are tuned, and in sign has solved that problem for the engi- evolved incorporates several features turn made up of three individual "pies ". neer. Other considerations that must be I think worth mentioning. As will be The effect of the "pie" construction gives a much sharper tuning coil than observed for high efficiency are low losses may be obtained by a lumped induc- itself. NEAT AND SELECTIVE and low capacitances in the switch tance of the same value. The gain in These points have been given serious B rear view of the receiver, showing selectivity obtained by this construction consideration and today switches are avail- the center unit, which is furnished alone is about 16%. The use of "pies ", able with silver contacts, insulated with complete. Figure 2, at right, is a -pass inter- together with the three tuned circuits, low materials mechanically de- comparison of the band -loss and mediate-frequency amplifier selectivity results in a resonance curve for the in- signed to have low capacities between and an ordinary i.f. amplifier using termediate stage which has a band their various conducting elements. high-0 tuning circuits width of only 25 KC at 100 times input voltage, and a band width of 5.5 KC at 2 times input voltage.

1000

B A A + B 100

O Q E ül 0

CURVE A CURVE B BAND-PASS HIGH -Q INTERMEDIATE INTERMEDIATE

A- - -A 465 KC MG. 2 NTERMEDIATE FREQUENCY -25 -20 -15 -10 -5 0 +5 +10 +15 +20 +25 KC OFF RESONANCE

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 539 BUILD" 35! designer of the famous Browning- inavrporating a startling array of new publishing this series they are per - Experimenters and Short -Wave Lis - DURING AN ALL -NIGHT TEST signal -to -noise ratio is important Seated at the control is the designer, with an operator and "ear- witness" at the Westchester Listening Post. This test One started at 6 p.m. and lasted until 2 p.m. the next day

The ordinary high -Q intermediate the best conditions when atmospheric Coupling from the oscillator to the in- stage has a band width of 36 KC at 100 static is exceptionally light. termediate- frequency stage is obtained times input voltage and 3.3 KC wide at A 2A7 is used as a mixer and oscilla- through the suppressor grid of the 58 2 times input voltage. It will be noted tor. As is well known this tube elec- tube. A switch in the plate of the 56 from the figures just given that not tronically couples the incoming signal tube oscillator turns off heterodyning only does the band -pass intermediate with the oscillators signal without in- frequency. A semi -variable condenser stage have greater selectivity but also teraction between the tuned -detector is used to tune this oscillatory circuit. will give better quality as the "nose" input and the tuned -oscillator circuit. For maximum signal strength this cir- of the curve is broader, thus passing the As used in this set, the second grid cuit should be tuned about 1000 cycles, higher modulating frequencies readily. (anode grid) is parallel fed through a above or below the intermediate fre- Figure 2 gives a graphical representa- resistance of 20,000 ohms. This allows quency. The intermediate frequency is tion of these facts. the switch arm on the oscillator tickler 456 KC, which was chosen after a Automatic volume control is ob- coil to be at low d.c. potential and at great deal of experimenting with the tained by the use of a 2A6 tube for the the same time "evens out" the voltage band -pass filter design. detector amplifier. A switch is arranged delivered by the oscillator over the The heart of the set is really the so that the AVC may be turned off at bands covered. Tobe Tuner which is essentially a will. An auxiliary volume control (on A beat -frequency oscillator is in- "catacomb" in which the twelve tuning the cathode of the 58 tube), when re- cluded as an integral part of the set so and oscillator coils are mounted. For tarded, precludes any possibility of that CW signals may be received. each of the four bands there are three this tube over -loading and causing sets of coils, one for the tuned - antenna cross modulation even under the sever- THE FUNDAMENTAL CIRCUIT circuit, one for the tuned -radio fre- est conditions. quency amplifier, and one for the os- The receiver has a sensitivity of well Figure 1. The fundamental circuit cillator circuit. These coil sets are all under one microvolt (over its entire application for the new receiver. The shielded from each other so that the Guilder, however, has to wire only a range which is 23 of one will in no way react on from megacycles to part of this, as the tuner section comes tuning 550 kilocycles) so that in practice this completely mounted and wired, requir- the others. In each of the three com- additional volume control on the 58 RF ing only seven connections to the rest partments there are four coils, that is, tube can he well- retarded except under of the set the oscillator (Continued on page 546)

58 2A7 BLUE GREEN B GREEN 2A II Ti T2 A5 tfi7i MFD

I IMO WÓ X X Lag L4 X x X X .0004 X x RED LYELLOW BLACK RED ELLOW MED. 5 * BLACK M EG 50,000 .05 / Ilc MFD OHMS II- T.02 m=oi MFD. .05 A / MFD. W .05 25 400 .4 ->. ; . EG OHMS M EG MFD. M SW .05 .i t { MFD. FD. .0004 .25 -10,000 M FD M F D. OHMS 400 M EG I OHMS .1 20,000 , 1000 _ .05 '40 MEG. OHMS OHMS Yaw: M FD M FD M EG RESISTORS 25,000 5000 ALL Y4 WATT OHMS OHMS UNLESS OTHERWISE c i SPECIFIED 50,000 2A5 05 FIELD OH FDM r____ GREEN 56 005 i 50 000 SW MFD. NUS &IMS 80 FOUR SW THE TUNER CONSISTS OF SETS OF COILS L4,L2,L3,L4,L5 LE, X I-0002 WITH ÁE TUNING 'AND TRIMMER X R8 T OHMS X X/(T CONDENSERS AND CHANGEOVER X MFD SWITCH FOR THE FOUR BANDS -MAW- A { ALL MOUNTED WITHIN ONE SPEAKER 400 1 M FD. ORÁNGE CONTAINER,pp! POINTS WHERE OHMS L X BLACK NE COILS ARE SWITCHED FIG. { W.

www.americanradiohistory.com 540 RADIO NEWS FOR MARCH, 1935 The Design of SATURABL E REACTORS Minute vacuum -tube regulation of heavy a.c. loads is made possible by this device THE MODELS Here are shown two reactors each of which when actu- ated by a type 45 tube is capable of controlling a 60- Myron J. Brown watt load

THE unlimited number of applica- lighting loads in theatres. Vacuum tubes 3. The d.c. flux magnetizes the iron and tions that can use the delicate and and grid glow tubes furnish the direct makes it less receptive for additional sensitive control offered by current. Another application employs magnetic flux from the a.c. coils, hence vacuum tubes has always been a fas- the reactor as a control for a neon lamp the a.c. impedance is lowered and more cinating study for experimenters and tuning indicator on automatic volume current will flow through the a.c. circuit. designers. control sets. A.C. impedance can be reduced to 10 or A radio impulse, a beam of light, a It is possible to control the tempera- 20 percent of its maximum value by sound wave, or a change in temperature ture of quartz crystal ovens by vacuum saturating the reactor with d.c. flux. Re- when transformed into electrical energy, tubes if the saturable reactor is used to actors can be built to handle any amount is capable of energizing the grid of a adjust the current through the heating of power from a few watts to many vacuum tube. Many applications of coils. Thermocouples would be used in kilowatts. vacuum tube circuits controlled by these the grid circuit, biasing the tube so as Vacuum tubes with high plate cur- physical quantities can be made when to raise or lower the oven current as rent will be found to have the best the output of the tube circuit controlled needed. Numerous other applications characteristics for operation with satur- is great enough to be used to regulate come to mind, such as radio controlled able reactors. Radio tubes such as the lights, motors, electric ovens, generators, lights, varying in brilliancy with the 45, 50, 71A, can be used. Industrial or the action of other electrical devices. strength of signal received; line voltage tubes are used with the larger reactors. The designer is often thwarted in de- regulators; generator voltage regulators; Grid glow tubes, thyratrons, externally veloping new uses for vacuum tubes and photo electrically controlled devices. controlled vapor rectifiers, and power when he finds that the amount of power amplifiers such as the RJ563, and available from easily procured tubes is The Principles of Operation DRJ 564 are suitable. inadequate for the direct operation of A schematic diagram of a saturable A wiring diagram of a simple reactor the device that he wishes to control. reactor is shown in Figure 2. Two a.c. circuit is shown in Figure 4 where a If a simple off and on operation is coils, having an equal number of turns, small direct current from a battery is sufficient, magnetic contactors (relays) are mounted on the outer legs of the used to control the brilliancy of lamps operated by the plate current of the reactor core. They are connected in in a large a.c. lighting load. Since the tube are suitable. But in cases where series. The inner leg is wound with a reactor is a series impedance there is a gradual gradation of the current ap- d.c. coil. very little power lost in it. Hence this plied to an electrical device is desired, With no current flowing in the d.c. circuit is far more efficient than one in some other means of current amplifica- coil, the a.c. windings form a closed core which the brilliancy of the lamps is tion is necessary. In this case, provided reactor whose impedance is roughly de- controlled by a series resistance. For a the circuits to be controlled are a.c. termined by the number of a.c. turns one kilowatt lamp load only ten watts circuits, saturable reactors have been and the amount of iron in the magnetic is required of the battery. A vacuum found very satisfactory. A saturable circuit. The a.c. magnetic circuit of the tube applied to the same circuit is shown reactor is a closed core reactor that can reactor is indicated by the solid line in in Figure 5. be magnetically saturated by the d.c. Figure 3. Under the condition where The first step in the design of a re- output of a vacuum tube. About 100 there is no d.c. flux the impedance of actor is to find the requirements of the times the power output of the tube can the a.c. circuit is high and the amount a.c. load being controlled. For an ex- be controlled. Thus a 2 watt radio tube of current passed will be low. ample let us consider a one hundred can control a 200 watt load. When a current is passed through the watt lamp load such as indicated in Commercial applications use the satur- d.c. coil a flux is set up in the paths Figures 4 and 5. About 10 volts through able reactor as a control for the large indicated by the dotted lines of figure a tungsten filament lamp will cause the

www.americanradiohistory.com RADIO NEws FOR MARCH, 1935 5-11

=n=oNo LAMPS VACUUM TUBE ozo=n= LAMPS 45 A.C. LIN E A.C. LINE

A.C. 3 / A.C. A.C. COIL COIL COIL A.C. COI L D.C. ^ D.C. COIL COIL POTENTIOMETER Á T. BAT SATURABLE REACTOR FIG.4 111100 111010 FIG. 5 C` BATT. B BATT

filament to be just visibly red. Hence The a.c. Coils and Core value. When the a.c. ampere -turns per this value could be considered as an The volts per turn will vary with the inch of length of the a.c. magnetic path ample minimum voltage for the lamp size of the reactor being designed. through the iron exceeds a certain value load. maximum Its voltage will be the A good value for this can be found the iron becomes saturated without the lamp rating, 115 volts. It is preferable to from the law: action of the d.c. coil. Hence the d.c. deal with current so we find the lamp coil has less effect than it would have current corresponding to these two volt- Volts per turn on an unsaturated core. The ampere ages. At 10 volts the current is about = .0034 X y'Maximum load wattage turns per inch are found by the follow- 18% of its 115 volt value. The decrease Apply this law to the 100 watt re- ing formulae (the letters "d ", "e ", and in resistance of the filament with a de- actor design: "a" refer to the stamping dimensions of crease in temperature explains why the Figure 6) : current is not proportional to voltage. Volts per turn = .034 X x/100 = .340 The full load and minimum load cur- The number of a.c. coil turns will be Ampere turns per inch = [(Total a.c. turns max. rents will be found as follows: found from the equation: X alternating current) - (60 X number of joints in a.c. flux Full load current Maximum patch)] divided by (2d +2c -4a) Lamp wattage Voltage on a.c. coils A.C. Turns While it is general practice to alter- Lamp voltage Volts per turn nate the stampings in a shell core assembly so that the joints first 100 watts This come on gives 132/.340 = 388 turns. one side of the coils and then on the = .870 ampere The sectional cross area of the core other, there is still a joint or air gap 115 volts in each outer leg is found from the between the "e" piece and the straight equation: Minimum load current stamping that must be considered. Applying = .18 X Full load current 375 X volts per turn this formula to our 100 watt reactor, using = .18 X .87 = .157 ampere Area (sq. in.) = a stamping of the follow- a.c. frequency ing dimensions, The line voltage will be the sum of the lamp voltage and the reactor voltage 375 X .340 v. p. t. a =ia inch; b =1/ inch; d =7 inches; e inches; drop at full load. Assume that the line Area = = 2.12 sq. in. =5% inch thick: voltage will be 15% higher than the 60 cycles Ampere -turns per inch= lamp voltage. Therefore it will be 132 A core is sketched in Figure 6. The [ (388 turns X .87 amperes) -(60 X 2)] volts for 115 volt lamps. number of core sizes which will give a For design purposes it is well to certain core area is unlimited, however 1 neglect the voltage across the lamps at there is only a certain range of sizes X minimum load and assume that the which gives desirable designs. No 14+10%-3g. total line voltage is across the re- definite law can be set down for select- 388 -120 218 ampere actors. ing a stamping so the usual method is = 9.5 turns Summarizing the requirements for a trial and error selection from the 2034 20.75 per in. dimming a 100 watt 115 volt lamp, we types available. Generally a core stack Values up to 10 ampere -turns per inch find that we need a reactor capable of ( "c" dimension in Figure 6) of 2 to 6 will be satisfactory. Above this point it changing a lamp load current from .157 times the width of the outer leg ( "a" in is well to increase the volts per turn and amperes to .870 amperes. The maximum Figure 3) is suitable. recalculate the design for the corres- voltage across the a.c. windings will be In selecting core dimensions a check ponding number of turns and core area. 132 volts. must be made on the a.c. saturation Having (Continued on page 583)

4.2 zw w

a .0

z .8 w cc cc .6 U .4 FIG.7 ó .2

o 20 40 60 SO 700 D.C. COIL MILLIAMPERES SATURABLE REACTOR CHARACTERISTICS

www.americanradiohistory.com i.9 RADIO NEWS FOR MARCH, 1935 Build the "A L L-S TA R"

Here is a simplified design for a home - constructed receiver for all -wave reception, from 10 to 550 meters. The design was produced to work efficiently with standard LOUDSPEAKER RECOMMENDED parts, available through radio dealers This is the small but efficient speaker recommended for use with the new All -Star Junior. Laurence M. Cockaday

j IKE its predecessor, the All -Star new i.f. coils, with the shielding spaced losses which would otherwise be pres- Junior receiver is completely band- far enough from the electro-magnetic 1 ent at 370 k.c. Each i.f. transformer spread for all frequency bands fields of the coils to have negligible employs a tuned primary and tuned sec- between 30 megacycles and 545 kilo- damping effect. This added spacing ondary, the impedance of which is cycles. Each band may be selected eliminates most of the eddy- current matched to the characteristics of the with the two knobs which operate the 6F7 and the 77 tube. The choice of the tank condensers; thereafter the tuning i.f. band for the receiver was the result is accomplished with the master airplane of extensive experiments, greater gain type dial. Its pointer travels over a You Will Need and reduced harmonics and image fre- 270° arc, thus spreading out the tun- quencies being secured at this range. ing of each range and spacing the Complete Instructions Six pairs of coils are recommended, closely -grouped trans -oceanic stations for Building This Set for complete coverage of the 10 to 550 far enough apart to permit accurate meter range. Each pair of coils con- logging. ADESCRIPTIVE folder on the sists of one antenna and one oscillator A new circuit, much easier to wire new All -Star Junior superhet- coil. The frequency coverage of each than that employed in the previous erodyne receiver is waiting for you, pair slightly overlaps the range of the model, uses new high -gain coils and i.f. following pair to help you build this set more of coils to assure com- transformers. The amplification se- plete coverage without skips. The pin - cured by the 6A7 tube and the 6F7 accurately and more easily. Simply plugs on the base of the antenna coil tube with the 77 pentode detector is address your requests for this in- fit a standard 4 -hole tube socket, while practically the same as that obtained the oscillator coil has five pins which fit formative literature to RADIO News, with the first four tubes of the original a standard 5 -hole tube socket. These All -Star set. A desirable feature is the Blueprint Department, 461 Eighth coils may be inserted with no more diffi- manner in which the tank condensers Avenue, New York City. The culty than putting sugar in your coffee. eliminate the need for an oscillator No shielding is employed on these folder will contain a schematic dia- coils, padding condenser. This, with the pre - due to the high losses which shielding tuned i.f. coils, makes special adjust- gram, three pictorial wiring dia- introduces in the field of high- frequency ments unnecessary. The Junior receiver grams, a parts list, as well as com- coils. The All -Star Junior is a receiver is ready to operate when the last wire designed for the short -wave plete assembly wiring and tuning fan who is soldered in place. The power -pack builds his own and who wants world- contains a "brute- force" type filter sys- instructions. These will be sent to wide reception and broadcast on the tem which effectually eliminates a.c. our readers free of charge. Send same set. hum from the reception. A standard Construction plans for the Junior your requests in early, as there is type 80 rectifier tube is employed. have been simplified by the use of three The intermediate- frequency amplifica- sure to be a long waiting list! pictorial wiring layouts, each showing tion is extremely high, due to the use of a successive portion of the wiring.

DET COIL 6A7 INPUT I.F. 6 F7 OUTPUT I.F. 77 42 G RFC 1 - - -, CB SPEAKS ° CA 1 o r ó ° X X X X C9 711111 R7 C2 4R/* R3 3 RS C2 o R2 CB m f P 1000 CA." C -OHMS G L L H 'u1=t* R6 C4- R7-4r X 111E

a 3 R4 ¡T C4 O rc G3 m 00600. 110V BLUE.; (bly019 60^"

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 543 JUNIO

When the constructor has completed dial will be found the these three projects in the wiring pro- beat frequency oscil- gram, the set is ready for its tubes and lator switch. The an- coils. No technical knowledge is neces- tenna tank condenser sary to assemble this receiver. A screw- is next, and it is not driver, soldering iron and pliers are all particularly critical in the tools required. A radio serviceman adjustment. The extreme right -hand FRONT PANEL VIEW could wire the receiver in four or five control is the volume regulator and a.c. Here is the new layout for the receiver. hours; a novice in radio might require power switch. The main center dial is the band - a couple of evenings on the kitchen The operation of the Junior receiver spread control. The lower controls table. If the instructions and plans are is very similar to the routine prescribed are explained in the text. In the lab- carefully followed, the results in either in the October issue of RADIO NEWS in oratory model the beat -frequency oscil- case will be the same-amazing per- 1934. With the power turned on, a lator switch and the local -distance first turn of the good antenna and ground or doublet switch were placed in reversed posi- formance with the tions. In the models these will connected, and a pair of coils (desig- regular switch. be as shown in the folder. The loudspeaker recommended for nated for the same band) in place, ad- use with the set employs a 1000 -ohm just the volume control full on. Set field with an inductive hum bucking de- the oscillator tank condenser at zero, for the station. This is particularly val- vice built in the field coil. The speaker with the condenser plates entirely out uable for DX reception, as often the comes equipped with a 24 -inch connect- of mesh. Adjust the antenna tank con- announcements are several minutes ing cord and a 4 -prong plug. The out- denser until a hissing sound can be heard apart and only the carrier wave of the put transformer is mounted on the at its loudest point. Then tune with the station can be detected with the aid of speaker and is designed to match the main airplane dial. When a station is the beat -frequency oscillator. Type 42 power tube to the speaker's heard, back off the volume control until From our experience with the previ- voice coil. The voice coil is so sup- the signal is clear. ous All -Star set and with the Junior, ported that warping of the cone will not For extreme distance reception, the we can highly recommend the doublet throw the coil out of alignment. A beat- frequency oscillator will be found type of aerial. It will eliminate the 6 -inch cone size is recommended for all most helpful. Flip the BFO switch major portion of the noises picked up ordinary requirements. An 8 or 12 -inch "open" and tune in a near -by station. in the high frequency wave bands. The speaker of the same type will reproduce A canary -like whistle will be heard as plain antenna and ground will prove the lower tones with greater fidelity. the main dial is tuned. The pitch of quite efficient on distant reception, but The controls on the receiver, from the whistle will first be very high and is often subject to interference from left to right in the front view of the will gradually deepen until it can't be passing cars and electrical disturbances. panel are: A local- distance switch heard; then raise in pitch as the dial is The new receiver, although much changing the C bias on the i.f. tube turned further. The exact point of res- simpler to construct than the earlier when the set is used with broadcast onance with the station is the spot where model, will prove to be an equally good coils. This arrangement makes the tun- the whistle has the lowest pitch. After performer, bringing in stations from all ing exceptionally sharp for broadcast tuning to this position, turn the switch over the world. The much lower cost of reception and prevents overloading of "off" or to the closed position and listen parts should now enable many more the detector tube on strong nearby sig- thousands of fans to build it. The whole nals. The second control from the left secret of its success lies in a careful de- is the oscillator tank condenser which SUB -BASE VIEWS sign using multi -purpose tubes so that do of will be found very sensitive to varia- Here are two views taken underneath few the work many! tions. Its position should be logged ac- the sub -base, to show the left end of When completed this little receiver curately for every important frequency the set and the right end, respectively, has the advantage of commercial ap- band. Under the main airplane tuning in greater detail. (Continued on page 581)

www.americanradiohistory.com 544 RADIO NEWS FOR MARCH, 1935 Experiments With MULTIPLA B.0 ' CH REGENRATION .../ R i Nothing intrigues the experimenter as does an = FIG.4 untried regenerative circuit. The author, a Polish experimenter, who has carried on extensive investigations of multiple regeneration, describes the methods employed and the results = - a T B.C. - - J. Plebanski

R TO date the application of the re- complicated and more expensive. Theo- generative principle has been lim- retically the special regenerative tube ited largely to the detector circuit. could be omitted and reaction taken FIG 2 It is quite clear that if controlled re- from the detecting tube. I tried such generation could be employed in more schemes; the results, however, were not than one circuit, the amplification would good, particularly as the set becomes be far greater and the selectivity con- very unstable. siderably improved. I searched for a more simple solution .: Take, for instance, a set with two and finally found out that taking the screen -grid tubes and three tuned cir- feed -back, not from the anode side of Lr cuits. If the input circuit is made regen- the tube. but from the cathode, particu- erative, for instance, by means of a larly with indirectly heated tubes, won- special tube, the grid of which is in derful results could be obtained. See parallel with the control grid of the Figures 1, 2 and 3. Such reaction can first radio- frequency tube, considerable be used with any tube, radio- frequency, improvement should be observed in detector, low- frequency screen -grid tube, amplification, selectivity, with inter - ordinary triode, pentode, etc., giving FIG. 3 modulation and amplitude distortion less absolutely stable conditions with prac- severe. This scheme is, however, more tically any circuit. First of all, I tried the circuit shown in Figure 1. The r.f. choke, CH, must have an inductance such that it re- sponds to a wavelength greater than the longest wavelength to be received. Many of the radio -frequency chokes used at present are suitable for such purposes. The grid -bias resistance, R. for the average screen -grid tube, must be about 600 -1000 ohms. The reactive windings, Lr, must be something from 5 to 15 turns, closely coupled to the grid winding. The regeneration control condenser, Cr, should be about .0005 mfd. The choke, Ch, and condenser, Cr, can be omitted if the reaction turns, Lr, are wound on a variable coupling member enabling adjustment of the coupling between tuning coil and reaction coil.

va L.S

I-3 B+ C- B+

FI G.4

www.americanradiohistory.com 545 RADIO NEws FOR MARCH, 1935

is of Such arrangements are shown in Figures cutting must be severe. That a certain extent. 2 and 3. course true, but only to reaction is really not critical, if For the short -wave range 10 to 100 Such 200 to the plate is connected direct to B+. meters and even for the range however, there are always 600 meters the reaction can be pushed In practice, -band subsequent tuned stages, and where such very far before appreciable side case regeneration cannot be cutting occurs. is the meters pushed to maximum, for if it is the set For the range of 1000 to 2000 starts to oscillate. It is interesting to the side -band cutting is more noticeable, note that in such a case the set oscil- but even in this range satisfactory con- only at one frequency, the first ditions can be found. While experi- lates I stage driving the next ones, whether menting with the set in Figure 4 they too are regenerative or not. There found, for instance, that upon strongly is, however, no need to push the re- regenerating both circuits I could reaction too far. Even slight regenera- ceive with adequate quality speech and tion will give much greater gain. music from Koenigswusterhausen (1600 In a set using one r.f. stage and a meters) while the local (Warsaw, Po- regenerative detector, the amplification land) station, only 12 miles distant, improved from 10 to 100 times worked with full power of 120 kilowatts, has been tuned circuits, such results are and the selectivity greatly increased by highly modulated on a wavelength of only two in the r.f. tube 1414 meters. From the point of view entirely impo3sible. introducing regeneration the above rein Figure 4. Cathode of selectivity, this is an excellent per- For superheterodynes circuit, as shown system (Continued on page 577) regeneration in the detector may be formance. Using any other set with action adjusted by means of a variable condenser Cr or by variable coupling between the tickler and grid coils. The cathode regeneration in the r.f. circuit is also adjustable and feeds back into the input circuit. It has been observed that an aerial connected direct to the tuning circuit gives the best results, and only a 5- or 10 -foot aerial can be used. The earth connection of the set makes practically no difference and can be omitted. Of course a larger antenna may be used if coupled inductively to the input circuit. However, this does not improve the selectivity. Using an indoor aerial of 10 feet or less, practically all stations can be heard with full volume, and selectivity is excellent. I tried also the diagram shown in Figure 5. The two reactions are taken from the same tube, V2. In this case it was found that the two reactions are not independent, as in Figure 4. As a result, if reaction is pushed too far in the detector circuit, then lowering reaction in the r.f. circuit will stop oscillation and vice versa. The two reactions can, however, be so adjusted as to regenerate both circuits adequately. It E means both circuits can be made sharp in tuning, or, if desired, one can be made to regenerate more than the other. However, the scheme in Fig- ure 5 seems to be inferior to that of Figure 4, which gives better selectivity, more amplification and is easier to adjust. One may say that with such a system of multiple regeneration the side -band

www.americanradiohistory.com 546 RADIO NEWS FOR MARCH, 1935

Into the lives of every short -wave fan there always comes one experience that makes him literally scratch his head and wonder. Well, the writer is not above such an experience and as it is really laugh- able we will recount it here. There was a special broadcast sent from CT2AJ, Azores, for the International DXers Affiance. We tuned for it and, although reception was far below par, we did manage to pull in this station and log over 23 minutes of the musical selections. The station signed off in code and we eventually sent them our reception report telling them the truth, i.e., how poorly we had received it. In the course of time we received this letter from the station's director. Quote: "We wish to thank you for your report dated Novem- ber 9th; it is rather difficult for us to posi- tively verify your report because such a report might easily refer to the transmissions of another station but it looks like you did pick us up. We quite agree with you about the interference on the frequency which we use and we shortly expect to be working either slightly above or below the 3500 -4000 kc. amateur band." Hi! Hi! -WAVE To SHORT PAGE which we might also - add, if they had kept an accurate log they surely would have known at least the time they signed off which according to our log was 9:08 RECEPTION conditions this winter east. The glass may be falling. This in- P.M., E.S.T. The part which says "looks have been the worst and most erratic dicates the', wind will shift to the north- like you did pick us up" has left us won- of any the writer has ever experienced west and be clear. If you note, with the dering. I know many a fan has received in all his years of "dial twirling." We rainy condition, the glass has not fallen, just such a letter as this from a station, have had wonderful DX days and then but raised a little, the stormy weather will and I sympathize with them. For my own an entire week of "almost nothing." We continue. Barometer readings range from part I would have preferred CT2AJ to have accounted for this condition by the about 28.30 to 31 in this hemisphere. If have said, "No, you did not hear us," or fact that the weather, here in the eastern your glass fell below 27, you would be "Yes, you did hear our transmissions." part of the United States, was just as blown off the earth, and there is no telling This station is on the air every Wednesday undependable as the signals from abroad. what would happen if a reading went and Saturday from 5 to 7 P.M., E.S.T., One day we were going out with a spring above 31. Nothing short of complete and gives their call -letters as "Aquo, Say, overcoat and the next imploring the su- evaporation would be the result! Again I Tay, Doix, Ah, Jhota. Now operating on perintendent of our apartment to "send repeat, the use of the barometer is a seri- 3500 kc. with .05 kw. power." They call up more steam" ! Two days later we ous study and when I see barometers in themselves "The Voice of the Atlantic ". would have the windows wide open and pictures of radio shacks I often wonder if The second paragraph in CT2AJ's letter the next the papers would be head- the fan knows what it is all about. My is very interesting. They say "Here are lining disasters at sea caused by gales of barometer has made many a trip around the two hot tips for you, Captain Hall: Sta- wind and waves, mountain high. - world with me and I know it thoroughly tion CTIGO, the short -wave transmitter of but if I neglect to keep a record of the the Radio Club of Portugal, in Parede, WE, in all our lack of knowledge of readings and weather conditions for at Lisbon, are now testing practically every just how radio waves are ruled, least two days, I am lost when it comes to night on 6196 kc. with about 2 kw., also, know that if the strongest thing on foretelling what weather we will have. the Emmissora Nacional, of Portugal, on earth, sea water, can be whipped to fury South American stations are everywhere 6207 kc., is testing with .500 watts. Both by the changing winds we can easily sur- but although their programs are sometimes these stations have been heard in these mise the disastrous effect these same winds very pleasing from an entertainment stand- islands during the last week at exceptional might have on the atmosphere that carries point, they lose many listener's interest strength and there is no reason why you all radio signals from over seas. I know because they talk so rapidly and rarely if should not get them well in New York. what that old North Atlantic can do ever identify themselves in any other Again thanking you for your letter, we (when she gets angry). Many a time I language but their own. I doubt very shall notify the management of your Club have left the bridge of my ship, every- much if even the thousands of Spanish - when we change frequency." thing fine. Wind mild, sea quiet. Within speaking, short -wave fans, here in the a few hours all hands would be on deck States can "make them out." I doff my getting ready to fight a raging sea, putting hat to the fan who can distinguish the on extra tarpaulins and battening down various call letters, especially the ones of hatches and watching the barometer for six variations. Is it a good old Spanish sudden highs or lows or keeping a lookout custom to send hours of musical selections for shifting of wind. These terrific dis- and then go off the air without giving call turbances are often experienced over the letters? Time and again I have written The Browning 35 North Atlantic and it is over this same page after page of a South American pro- sea that signals from Europe have to gram, into my log book, only to have the (Continued from page 539) come in order to reach us. announcer sign off with "Good night every- Speaking of barometers, reminds me that body". coils for each of the four bands are many of my short -wave fan friends have More International Reply Coupons are mounted in one compartment, the antenna just bought barometers. I have had nu- sent to South American stations, without coils in the second compartment and the merous requests about the use of one as results being obtained than any other coun- r.f. stage coils in the third compartment. it has been my life's companion. The try throughout the world. I do not think Each compartment also contains the asso- barometer is useless to anyone who does I am alone when I say, "I am thoroughly ciated switches. These switches have silver - not thoroughly understand it as well as the disgusted with the stations bordering on plated contacts, low losses and low capaci- directions of winds, movements of clouds the equator." Some exceptions are made, ties, and are so designed that all coils that which should be noted at least every four and to these stations we certainly should are not used are short -circuited. This elim- hours. Just looking at a barometer and be thankful. HC2RL, PRADO, HCJB, inates any resonance effects in the larger taking a reading means nothing. The let- both the Caracas stations and HJ4ABB all coils when the set is operating on the tering on the glass, i.e., Dry, Fair, Change, verify correct reception reports but as for higher- frequency bands. A great deal of etc., does not mean a thing, it is only there the rest it is almost a waste of energy to thought was put into the mechanical as for decoration. write to them. My mail is overflowing well as electrical design of the tuner, and I will give you one example of the action with complaints about the South Amer- as a result, all leads are exceptionally short. of a barometer. Let us say that it is ican stations that "wander" on the ether To reduce losses to a minimum, bare wire raining in the morning. The first thing to waves and defy identification and even if is used in making all connections. The do is note the direction of the wind. The identified, ignore all letters addressed to high- frequency -band coils are "space - wind will be either south, south -east or them. (Continued on page 579)

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 547

Informal rests on a 13 -550 MET ER "SUPLRHET (Scott All-Wave 15) S. Gordon Taylor

6 RUNNING back over receiver designs of the past ten years em- phasizes the tremendous advan- A HOME INSTALLATION tages offered by present -day receivers. A wide variety of consoles is available for housing this receiver. Or, because of Naturally, improvements were to be the beautiful appearance of the chromium- plated chassis, it can be exposed to expected, but it is extremely doubtful view, as in the installation shown here that anyone, ten years ago, could have been optimistic enough to vision many each of its four positions the dot color noise reduction but also less sensitivity of the refinements which are now an indicates the scale in use. than the middle position. accomplished fact. This was brought All tuning is accomplished by means In addition to these controls, there is to mind quite forcibly during the tests of a single knob with no auxiliary tun- a continuously -variable bass -control of the Scott "All -Wave Fifteen" re- ing controls of any kind. The tuning knob at the rear of the chassis. This ceiver which was recently put through indicator line takes the form of a permits a variation in tone to meet in- its paces by the RADIO NEws staff. shadow thrown across the scales them- dividual taste and is also further help- As its name implies, this receiver em- selves and is therefore not subject to ful in reducing the effect of local elec- ploys 15 tubes which provide one r.f. parallax. The shadow of the tuning trical interference. stage, tuned in all wave ranges by one meter needle is also thrown on the cali- Automatic volume control is, of section of the single -control gang con- brated scales so that the receiver may course, a feature of the receiver, and denser; separate tubes for first detec- be tuned to resonance (as indicated by that the system employed is highly ef- tor and oscillator; three i. f. stages; the tuning meter) without taking one's fective is evident from the fact that type -55 second detector; three audio eyes off the scale calibration. This tun- stations near and far are tuned in with stages, utilizing a 56 tube in the first ing meter, incidentally, is a vast im- approximately equal loudspeaker vol- stage, 56's in the second stage and provement over most of those in use ume without readjustment of the push -pull 2A3's in the power out- today, inasmuch as an unusually wide manual volume control knob. put stage; a beat -frequency oscillator deflection is obtained. In actual opera- As is the Scott custom, the chassis which is cut in and out by a push -but- tion in New York City, the shadow of and power unit are both finished in ton immediately below the wave -band this needle deflects more than an inch chromium throughout. The equipment switch on the front panel; and a 56 on local stations and up to a half -inch may, therefore, be left exposed to view tube used as a tuning meter amplifier, or more on stations 2000 -3000 miles dis- and, unlike some present -day receiver its purpose being to exaggerate the tant. In effect, it was found that any chasses, presents a pleasing appearance. swing of the tuning indicator needle so station strong enough to be heard There are, however, a wide variety of that it will properly indicate resonance above the local noise level results in a console cabinets available for use with even on weak signals. A 5Z3 rectifier is sizable movement of this needle. The this equipment for those who prefer employed. result is that even the most distant DX this type of installation. The loudspeaker and the power pack - stations can be tuned in with the vol- So much for the general description power amplifier are separate units which ume control set at zero, then the of the receiver. It was put through are interconnected by means of a plug volume turned up as desired. Thus it comprehensive tests by the RADIO NEWS and cable. Another cable connects the is possible to accomplish DX tuning in staff and was found to be exceptional tuner chassis to the power unit. This complete silence -a decided asset to in many respects. On the broadcast power unit includes the power supply those who do their DXing late at night. band the sensitivity is really amazing for the entire receiver, the field supply The only other controls on the front -and by sensitivity is meant the usable for the speaker, and the push -pull panel are the audio volume control, sensitivity. The actual high sensitivity power output stage. This power stage which provides for any desired varia- of the receiver is only one factor, the provides a rated output of 11 watts of tion of output from zero to the full 11 other being the unusually favorable undistorted power. The speaker em- watt capacity; and a 3- position switch signal -to -noise ratio. The over -all re- ployed is a new type which has an for noise control. In the right -hand sult is that during the heart of the excellent response characteristic to bet- position of this switch, high- fidelity re- early evening stations 2000 miles dis- ter than 8000 cycles. production is provided for use in tun- tant can be tuned in with real program The receiver continuously covers a ing local stations. In the center posi- value, night after night, even in a range from 13 -550 meters, in four tion a high degree of sensitivity is pro- mediocre location. bands. The desired band is selected by vided but a considerable amount of Perhaps the best illustration of this means of a range -selector switch and noise reduction is obtained. In other feature is found in the fact that it was the tuning dial is calibrated in kilo- words, in this position the signal -to- possible to tune in three European sta- cycles (or megacycles) for each range. noise ratio is excellent and this positions (on the broadcast band) in one Each calibration shows up on a strip of tion is used for DX tuning where high - of the New York City Listening Posts different color and the wave -change fidelity is not imperative. The left - where it had never before been possible switch has four colored dots so that in hand position provides still further to tune in (Continued on page 585)

www.americanradiohistory.com 548 RADIO NEWS FOR MARCH, 1935

W2DLG, WORLD'S HIGHEST

"HAM" . STATION Inside the Garden City Radio Club's "Shack" on the 41st floor of the Hotel New Yorker. Starting at the left, the equipment includes a home -made power supply, the Lynch Airod, a National 5 -meter Superhet- converter, a Federated Microphone Control Box, a telegraph key, and a National audio oscillator. Directly above this hangs the speaker. To the right of Arthur H. Lynch, who is shown on the job, is a National SRR 5 -meter receiver; next, a Federated No. 196 speech amplifier, and, above, a 2 -stage pre -amplifier (used with a crystal microphone at the operator's right hand). At the extreme right is the complete 28 -watt, 5 -meter transmitter

of parallel rods, each 42 inches long, provide the sole means of tuning the transmitter. Two are used to tune the plate cir- SHACK cuit; two to tune the grid. The rods them- THE "HAM" selves are % -inch hard -drawn copper tub- CQ CQ CQ ing and are mounted vertically. The plate circuit rods are arranged so their centers are 1 inch apart and parallel. The grid circuit rods are arranged in a similar man- THE amateur has conquered another The station has been set up in a corner ner, but are placed about 6 inches from problem. The problem is that of of the elevator control room on the 41st the plate rods so when mounted, the four floor operating on ultra -short wavelengths and of the building, through the kindness rods form a rigid four -legged table with a of the hotel's management maintaining reliable communication over and the efforts 6 -inch by 1 -inch top and 42 -inch legs. This distances beyond those anticipated by of Eli M. Lurie, chief radio engineer for facilitates mounting the tubes and compo- the pioneer experimenters who first all of the hotels under the management of nent parts in a symmetrical arrangement delved into the possibilities of these fre- Ralph Hitz. The club negotiated the ar- between the tuning circuits, thus providing rangements quencies as long ago as 1928, and in some with the New Yorker through the shortest possible leads. The high volt - instances before that. Early experiments Arthur H. Lynch, W2DKJ, who needs no (Continued from page .573) indicated that frequencies of the order of introduction to short -wave experimenters. twenty -eight megacycles and higher had The transmitter was designed by Stanley characteristics similar to light and, for P. McMinn, W2WD ; was constructed by z--- that reason, could not be transmitted Edward Ruth, W2GYL, and belongs to much farther than the range of vision. Lynch. The call letters are W2DLG. More 14'-w than 100 contacts, some over a distance of WITH the pioneering work done and 60 miles, have been made. Thus far the the evolving of a more or less ade- complete plan of the Atlantic Coast net- quate means of communication on work has not been realized, but it is be- the ultra- short -wave channels (although lieved further experiments and tests with i there is still a vast amount of room for im- directive antennas will bring the group i/ provement) others, with a little less of the nearer to its goal. pioneering spirit but nevertheless with an The station itself is not much unlike the adequate supply of experimental intuition, average 5 -meter "ham" installation. The ' --FEEDERS MAY BE have followed. Within the last three or transmitter consists of a pair of Sylvania. ANY CONVENIENT four years there has been a tremendous in- 801 tubes in a push -pull oscillator circuit LENGTH crease in activity on 5 meters (sixty mega- with a so- called "long lines" tuning ar- cycles). Increased activity has made pos- rangement. This arrangement is a radical TO TRANSMITTER sible further experimentation and has departure from the conventional coil sys- greatly facilitated the work of the pioneer- tem of tuning and is gaining wide favor W2DLG'S ANTENNA ing group who are still seeking to probe among 5 -meter experimenters. Two sets further into the possibilities of the ultra- high frequencies. Much interest now is TO ANT. centering in the possibility of transmitting iZ 801 5 -meter signals beyond the line of vision, with the result stations have been erected at the highest possible locations, including 15.000 mountain tops and tall buildings; experi- OHMS mentation has progressed with types of antennas that concentrate a signal in a given 0- 50,000 OHMS, direction with greater field strength and VARIABLE carrying power. MICROPHONE One of the most interesting experiments along this line has been conducted by the Garden City Radio Club, of Garden City, o Long Island. This organization is exceed- ingly active on 5 meters, 2% meters as well as on 1/- meter tests that have at- 25.000 ,2MFD. tracted wide attention. Their latest inter- OHMS est has been to participate in an attempt to 25 MA organize a "network" of stations linking 2000 OHMS Boston with Washington, D. C., with relay NMI points at Hartford, New York, Philadel- phia and Baltimore. The Garden City group engineered the erection of a 5 -meter station atop of the Hotel New Yorker, a 42 -story building not far from the Hudson River that commands a line of sight of 60 with practically no ob- close to miles, 750 r structions in north, south or westerly di- OHMS" Y SMOOTHING INPUT z - 1í0V. rections. The towering Empire State build- CHOKE CHOKE ing is to the east. A;C.

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 549 `adio News Laboratory SHORTWAVE CONVERTER S. Gordon Taylor

AST month a brief discussion of then found highly short wave converters was pre - impractical to spe- J sented in which it was pointed cify homemade out that possessors of good broadcast coils for the con- band receivers could obtain excellent verter because it short wave results through the use of a was found utterly THE ORIGINAL CONVERTER MODEL converter. It was fur- impossible to ex- properly designed It is expected that the Tinal model will be more compact than ther stated that such a converter was actly duplicate the this unit, but capable of equally good results. in process of development in the Radio originals. The re- News Laboratories, and would, it was sulting variations hoped, be completed in time to be de- would either make alignment of the rather complicated series of "cut -and- of a scribed in the present issue. three circuits impossible throughout the try" adjustments in which the use The development model was com- entire band, or the band width would signal generator and output meter were pleted and proved to be eminently satis- be reduced, chopping off some of the practically essential. factory until attempts were made to du- 49 meter stations or some of the 19 After extensive investigation along plicate by hand the original homemade meter stations. The only way of over- these lines it was concluded that the coils employed in this model. It was coming the difficulty was through a most practical (Continued on page 586)

LI La r How to Improve Your REUENERATIVE

FIG 4 RECEIVER PHONES

- A+ A- B+ Br 22V 90-435V. Robert Hertzberg L2 C.IMFD .5MFO LEMENTARY short -wave receiv- if a screen -grid detector is used). In ers of the straight regenerative 1928 RADIO NEWS featured a set using F type continue to be highly popu- this identical circuit under the name lar in spite of the advanced state of "The Junk Box Receiver ", and more of it were dis- TI superheterodyne development, because than 75,000 blueprints .. and If the present mail is any in- MFD they are cheap and easy to build tributed. 400 of pulling in dication, this set is still in very wide OHMS because they are capable on the short -wave service. FIG.2 RI most everything bands. An a.c. version, also very popular, is B- Be 435V Be 250v However, there are two little features shown in Figure 2. The essential radio - L L2 of straight regenerator operation that frequency portion is the same as before, 58 pentode and C4, 03 arouse a steady stream of inquiries but V1 is usually a type TI These V2 either a 56 or a 2A5, and regenera- I v1 from otherwise satisfied users. are irregular feed -back and lack of se- tion is controlled by a screen potentio- lectivity. The first trouble can be meter Rl. T2 is merely a plate choke. cured by a little revamping of the cir- A separate power pack furnishes 2.5 C5 R2 cuit, but the second is a real problem. volts a.c. for the heaters of the tubes A- A+ The circuit of Figure 1 represents in and 135 to 250 volts d.c. for the plates C6 .OI MFO a general way thousands of little sets and screens. complete REST OF that have been exploited under dozens Irregular feed -back and 67V 435V FIG.3 in most cases to an- UNCHANGED of different names, and will serve our dead spots are due Most of these sets tenna absorption. Adjustment of the V3 LI L2 purpose for analysis. are dry -battery operated, V1 being a 30 antenna coupling condenser C3 may help 4 C2 or 32 and V2 another 30 or possibly a to relieve this on one coil but not on 33 pentode. Invariably Ll is a two - another. The dead spots may disappear, winding plug -in coil, Cl a 100 or 140 but sometimes the signals go with them. mmfd. tuning condenser, C2 a similar In Figure 2, different value at C2 may condenser for regeneration control, C3 help also. a "postage stamp" trimmer for antenna By far the best thing to do is to add RI coupling, C4 a .0001 mf. mica conden- another tube as an untuned r.f. ampli- .OI 3 4. This MFD, R1 a filament rheostat, R2 a 2 to 5 fier, as shown in Figures and 75 000 ser, OHMS leak, L2 a small r.f. choke and thoroughly isolates the sensitive regen- 300 FI G.4 B+ megohm OHMS Tl a small audio transformer (or choke erative circuit (Continued on page 567)

www.americanradiohistory.com 550 RADIO NEWS FOR MARCH, 1935

S.W. PIONEERS Official RADIO NEWS Listen- ing Post Observers below by States are the Official LISTEDRADIO NEWS Short-Wave Listening Post Observers who are serving conscientiously in logging stations for the DX Corner: United States of America: Alabama, J. E. Brooks ; Arkansas, Don Pryor, Jas. G. Moore ; Arizona, Geo. Pasquale ; California, E. G. De- Haven, C. H. Canning, O. I. Noda, E. S. Allen, A. E. Berger, Ralph Leavitt, Geo. C. Sholin, Wesley W. Loudon; Colorado, Wm. J. Vette, F. Erich Bruhn ; Connecticut, Phillip Swanson, Geo. A. Smith, H. Kemp; District of Columbia Douglas S. Catchim; Florida, Geo. H. Fletcher, E. 'M. Law, James F. Dechert; Georgia, James L. Davis, C. H. Armstrong, Guy R. Bigbee, John McCarley ; Idaho, Bernard D. Starr, Lawrence Swenson; Illinois, Phillip Simmons, E. Bergeman, Robert L. S. W. TIME SCHEDULE Weber, Floyd Waters, Chas. A. Morri- son; Indiana Freeman C. Balph, J. R. LAURENCE M. COCKADAY Flannigan, Henry Spearing; Iowa, J. Harold Lindblom ; Kansas, C. W. Bourne, Wm. Schumacher ; Kentucky, Charles Miller, Wm. A. McAlister, Geo. THE 24th installment of the DX Cor- tional DX'ers Alliance, President, Charles Krebs ; Louisiana, Roy W. Peyton ; ner for Short Waves features a new A. Morrison; Newark News Radio Club, Maine, R. I. Keeler ; Maryland, Howard method of presentation Adams, Jr., James W. Smith, J. F. for the World Irving R. Potts, President, A. W. Oppel, Fritsch ; Massachusetts, Armand A. Short -Wave Time -Table for 24 -hour use Executive Secretary ; Society of Wireless Boussy, J. Walter Bunnell, Harold K. all over the world. The list starts at Pioneers, M. Mickelson, Vice- President; Miller, Donald Smith, Elmer F. Orne, 01 G.M.T. and runs 24 hours through 00 U. S. Radio DX Club, Arthur Hamilton, Roy Sanders ; Michi- Geo. E. Deering, Jr., gan, Stewart R. Ruple ; Minnesota, Dr. G.M.T., right around the clock! This President ; the Radio Club Venezolano of G. W. Twomey, M. Mickelson; Missis- new Time -Table contains a List of Short - Caracas, Venezuela, President, Alberto Lo- sippi, Dr. J. P. Watson, Mrs. L. R. Wave Stations, logged the last pez. Any Ledbetter; Missouri, C. H. Long; during DX fan wishing to join any one Montana, Henry Dobrovalny Nebraska, month in the RADIO NEWS Westchester of these Clubs or Associations may write P. H. Clete, G. W. Renish, Jr., Harold Listening Post (in our Editor's home), for information to the Short -Wave DX Hansen ; New Hampshire, P. C. At- wood, A. J. Mannix; New Jersey, Wil- as well as at our official RADIO NEWS Editor, and his letter will be sent to the liam Dixon, R. H. Schiller, Wm. F. Short -Wave Listening Posts throughout organization in question. Other Clubs who Buhl ; New Mexico, G. K. Harrison; the world. It provides an hour -to -hour wish to become affiliated should make their New York, Joseph M. Malast, Capt. Horace L. Hall, S. G. Taylor, John M. guide to short -wave fans, whether experi- application to the Short -Wave DX Editor. Borst, Wm. C. Dorf, R. Wright, I. H. enced or inexperienced. The new type Clubs associated with the DX Corner have Kattell, Donald E. Bame, Albert J. of Time -Table shows the Call Letters, the privilege of sending in Club Notes for Wm. Koehnlein, Edmore Leonhardt, Station Locations, Wavelength and Fre- publication in RADIO NEWS. Melanson, H. S. Bradley ; Nevada. Don H. Townsend, Jr. ; North Carolina, H. quency in the middle column. The col- O. Murdoch, Jr., W. C. Couch, E. umn at the left gives the times of Trans- Your DX Logs Welcome Payson Mallard ; Ohio, Oker Radio & Electric Shop, R. W Evans, C. H. mission, in G.M.T. a.m., and the column Please keep on sending in information Skatzes, Donald W. Shields, Albert E. at the right gives the Times of Trans- on any stations and Best Bets that you Emerson, Samuel J. Emerson, Clarence mission, in G.M.T. p.m. The correspond- D. Hall; Oklahoma, H. L. Pribble, hear during the coming month, getting Robert Woods; Oregon, Virgil C. ing time in E.S.T. is also given and space them in to the short -wave DX Editor, by Tramp, James Haley, (Geo. R. Johnson; has been left for filling in your own Local the 20th of the month. In this way you Ned Smith ; Pennsylvania, Edward C. Time The time, E.S.T., in the U. S. Lips, K. A. Staats, C. T. Sheaks, share your "Best Catches" with other George Lilley, John A. Leininger, F. L. would be 8 p.m., E.S.T., for 01 G.M.T., readers and they, in turn, share with you Stitzmger, Hen. F. Polm, Chas. Nick; as there is a five -hour difference. The making for improved general knowledge on Rhode Island, Joseph V. Trzuskowski; time E.S.T. for 13 G.M.T. would, there- South Carolina, Ben F. Goodlett, Edw. short -wave reception. Our Editors are 8 E.S.T. fea- F. Bahan ; South Dakota, Paul J. Mraz ; fore, be a.m., These two doing the same thing, working with you Tennessee, Charles D. Moss, Adrian tures can be seen at the beginning of day and night, to bring you the best and Smith; Texas, Heinie Johnson, Bryan each outside column in the new Time - Scott, John Stewart ; Utah, Harold D. most reliable short -wave information. Nordeen; Vermont, Joseph M. Kelley, Table. The times, C.S.T., for these two Your logs are welcome and are sincerely Eddie H. Davenport ; Virginia, Gor- corresponding hours would be 7 p.m., invited. don L. Rich, G. Hampton Allison, D. C.S.T. and 7 a.m., C.S.T. The times, W. Parsons ; Washington, A. D. Golden, Glenn E. Dubbe, Chas. G. M.S.T., for the corresponding hours would Listening Post Observers and Payne; West Virginia, Kenneth Boord, be 6 p.m., M.S.T., and 6 a.m., M.S.T. Other Fans Please Notice! R. E. Sumner ; Wisconsin, Willard M. The times, P.S.T., for corresponding hours Harden, Walter A. Jasiorkowski; Wyo- Listed below is this month's partial in- ming, Dr. F. C. Naegeli. would be 5 p.m. and 5 a.m., P.S.T. In Applications for Official Observers in this way American listeners can easily formation regarding short -wave stations, the remaining States should be sent in heard and reported by our World -Wide immediately to the DX Corner. fill in their own Local Times at the top of the columns. Foreign listeners would Listening Posts. Each item in the listing probably prefer to use G.M.T., anyway, is credited with the Observer's surname. S.W. LISTENING POSTS or, if not, can compute the time differ- This will allow our readers to note who Summer listening post ence from G.M.T. and fill in their Local obtained the information given. If any of "shack" of our readers can supply actual Time Sched- Senor Eduardo Hiero. He is the offi- Time in each column head. We earnestly cial announcer of Station HJIJIBG, request our readers to give us their opin- ules, actual Wavelengths, correct Fre of Barranquilla ions of the new Time -Table, as we think quencies, or any other Important Informa- it is simpler and saves turning over four tion regarding these items, the DX Corner readers pages to find out the schedule of a par- Editor and its will be glad to get ticular station at a particular time of day. the information. There are some hard in listings, At the end of the Time -Table is a List stations to pull in these but we of Symbols, covering the various irregu- urge our Listening Posts and other readers larities of transmission, schedules, etc. to try their skill in logging the stations and We believe our readers will find this new getting correct information about them. you system a superior one when they have When are satisfied that you have this become familiar with it. information correct, send it in to the editor; or if you have received a "veri" from Affiliated DX Clubs any of the hard -to -get stations, send in a copy of the "veri" so that the whole short- We are hereby placing a standing in- wave fraternity may benefit. The list vitation to reliable DX Clubs to become follows: affiliated with the DX Corner as Associate 12R0, Rome, Italy, was reported (also Members, acting as advisers on short -wave as IRA) 49.2 meters with a program in activities, in promoting short -wave popu- English from 5:15 -7:30 p.m., E.S.T. Some larity and reception efficiency. A list of other listeners reported him as on 49.05 associate organizations follows: Interna- meters, on 6115 kc., and on 6120 kc. From

www.americanradiohistory.com 551 RADIO NEWS FOR MARCH, 1935

S.W. PIONEERS Official RADIO NEWS Listen- ing Post Observers LISTED below by countries are the Official RADIO NEws Short-Wave Listening Post Observers who are serving conscientiously in logging stations for the DX Corner: Argentina, J. F. Edbrooke. Australia, C. N. R. Richardson. C. Arthur Matthews, A. H. Garth, A. E. Fanti. Bermuda, Thursten Clarke. Brazil, W. \\ . Enete, Louis Rogers Gray. British Guiana, E. S. Christiani, Jr. British West Indies, E. G. Derrick, N. Hood - Daniel, Edela Rosa. Canada, J. F. Atkinson, Jack Hews. H. Fraser, Charles Armstrong Robert Eakins, W. Courtesy C. H. E. Roy, A. G. Taggert, Douglas Wood, INTERIOR OF STATION PRADO, AT RIO BAMBA A. B. Baadsgaard. THE Canal Zone, Bertram Baker. igt Ecuadorian, South American, station, showing the trans- Island, Manuel Davin. This is a view of the Canary Tatum. and the control desk with two well -known receivers for monitoring Central America, R. Wilder mitter panels Chile, Jorge Izquierdo. China, Baron P. D. N. von Hoynin- gen- Huene. measurements at the Westchester free, Potts, Herren, Hall, Fritsch) Colombia, Lowe, Italo Amore. our own H Dr. Evelio 'w we believe it is about 6085 Prado, Riobamba, reported heard on Cubauba, Franknak H. Kyd, Listening Post, Villar. kc. Exact frequency is requested. (Re- 6200 kc. Denmark, Hans W. Priwin. C. D. Hall, Frame, Lawton, An experimental short -wave station was Dutch East Indies, A. den Breems. ported by R. J. van Om- Potts, Fritsch, Vassallo, Edge, Maugeri, heard testing in Cienfuegas, Cuba, on 6180 Dutch West Indies, York meren. Kalmback, Spaulding, W. T. Thompson, kc., 8 -9 p.m., E.S.T., calling New England, Alan Barber, Donald Burns, and COH, and playing music, etc. (Spaul- Leslie H. Colburn, C. L. Davies, Fred- Spearing, Oker and Robinson) W. P. B. W. I., 7000 kc., ding) erick W. Gunn, R. S. Houghton, VP6TB, Barbados, Kempster, R. Lawton, John J. Mating, reported as an Amateur doing broadcasting. CM6XS, Tuinucucu, Cuba, 36.28 meters, Norman Nattall, L. H. Plunkett - 8.25 megacycles, reported sending music, Harold J. Self, N. C. Smith (Rosa) Checkemian, L. C. Nicaragua, 20.7 meters, etc., afternoons and evenings irregularly. and John Parkinson, R. Stevens, YNA, Managua, Styles, C. L. Wright, John Gordon 14485 kc. (Pasquale) (McCarley) Hampshire. CT2AJ, 83.5 meters, 3600 kc., reported HI4D, La Voz de Quisqueya, San Do- France, J. C. Meillon, Jr. Azores. mingo, D. R., 46.25 meters, 6482 kc., heard Germany, Herbert Lennartz. as being San Miguel, (Pasquale) Hawaii O. F. Sternemann. OAX4C, Radio Dusa, Lima, Peru, re- 11:55 a.m. to 1:40 p.m., E.S.T., and from India, b. R. D. Wadio. ported heard 7 -10 p.m., E.S.T., on 6230 4:40 -7:40 p.m., E.S.T., except Sundays. Italy, Dr. Guglielmo Tixy. well as (Hall, Armstrong, Malast, McCarley) Japan, Masall Satow. kc., also reported on 51 meters as Malta, Edgar J. Vassallo. 13,000 kc. Also reported on the air VUB, Bombay, India, 31.36 meters heard Mexico, Felipe L. Saldana. E.S.T. Other listeners report with special Armistice morning program New Zealand, Dr. G. Campbell Mac - 9 -11:30 p.m., Moffatt. still 5 -7:30 a.m., in Ponoka, Canada. (Baads- diarmid, Kenneth H. this station as OAX4D, as OAX4B; Norway, Per Torp. others say it is OA4AD and OA4D. (Sal - gaard, FB OM, Ed.) Philippine Islands, Victorino Leonen. dana, Tobler, Baker, Skatzes, D. Smith, TFK, Reykjavik, Iceland, heard on 9050 Portugal, Jose Fernandes Patrae, Jr. H. kc. (Sholin, Armstrong) Scotland, Duncan T. Donaldson. Wright, McCarley, G. R. Johnson, South Africa, Mike Kruger, C. Mc- Johnson, Armstrong, Miller) VK15, 6425 kc., heard 2 -3 p.m., E.S.T. Cormick. CT1GO, Parede, Portugal, heard on 48.4 (Twomey) Spain, Jose Ma. Maranges. HI7G, San Domingo, D.R., reported Switzerland, Dr. Max Hausdorff, Ed. meters and on 24.2 meters testing. (S. J. J. de Lopez. Emerson, Vassalo, Lawton, Styles, D. T. heard. (Spaulding) Turkey, Hermann Freiss. Donaldson) HBJ, Switzerland, 20.6 meters, 14.60 kc., Venezuela, Francisco Fossa Ander- heard 1 -3 p.m., irregularly (Mc- son. HP5B, Panama City, 6040 kc., 49.75 reported Applications for Official Observers in meters, heard on the air 6 -10 p.m., E.S.T. Carley) the remaining countries should be sent (S. J. Emerson, Arms, Malast, Saldana, CT1CT, Lisbon, Portugal, 24.83 meters in immediately to the DX Corner. Twomey, Miller, D. Smith, Skatzes). Also now reported on the air with an extra pro- heard testing on 25 meters. (Baker) gram 14 -16 G.M.T. Sundays and 20 -21 Jose, Costa Rica, G.M.T. Thursday. (Styles) TGTH, Almatica, San OBSERVER FOR 52 meters, 7:20 p.m., LCL, Jeloy, Norway, reported heard OFFICIAL heard on 5760 kc., SCOTLAND E.S.T. ( Saldana) again on 48.9 meters. (Lawton) Rome- was reported testing on 49.5 HB9B, Switzerland (Basle Radio Club) Duncan T. Donaldson, of Kelty, Fife, meters at 15 G.M.T. (Smith) 42.14 meters, reported heard 21 -21:30 Scotland, seated in his DX corner Radio L.L., Paris, may be heard testing G.M.T. (Lawton) showing some of the verification cards. 3 days a week on 80 meters, 3.7 megacycles, EA4AQ, Madrid, Spain, 43 meters, re- It isn't necessary to say what magazine with 200 watts. (Meillon) ported heard 20 -22:10 G.M.T. (N. C. he reads y IRM, Rome, Italy, 9820 kc., heard Smith) 3 -4:30 p.m., E.S.T. (Eisler, N. C. Smith, VE9CS, Vancouver, B. C., is reported to Daboll, Oker) be transmitting with only 2 watts of power. I2R0, Rome, Italy, heard testing on its Anyone hearing him is doing some real DX regular wavelength of 25.4 meters. (Gunn, work. (Fletcher) Haley, Westchester Listening Post). Some XEBT now seems to be transmitting on other tests by I2R0 were reported as 42.3S less than 6010 kc. (may be about 6000 kc.) meters from 5 -5:15 p.m., E.S.T. 36.7 meters and is interfering less with COC. (Fletcher) 2:40 -5:30 p.m., E.S.T. 31.25 meters, 3 -5 HJ2ABA, Tunja, Colombia is reported to p.m., E.S.T. (These special tests were re- be now on about 48.6 meters instead of 50.4 ported by C. H. Armstrong. FB OM, Ed.) meters. Who knows its exact frequency? IRS, Rome, Italy, reported on about 37 (Armstrong) meters, also on 42 meters. (D. Smith, PSK now reported on the 49 -meter band. Oker, S. J. Emerson) Who else has heard them? (T. Clarke) HIH, La Voz del Hieuamo, San Pedro KBJ, Manila, P. I., reported heard on 22 de Macoris, D. T., 44 meters, 6814 kc., meters, 09 -11 G.M.T., sending musical and 75 watts. 12:30 -2 p.m., 7 -8 p.m., daily special programs to Japan. (Matthews) E.S.T. An extra program on Sunday, CJRX, 11,720 kc.; CJRO, 6150 kc.; 4:30 -5 -30 p.m., E.S.T. (Armstrong) VEGGW, 6095 kc.; VE9DN, 6005 kc., are COH are the correct call letters of the all reported as transmitting news, messages, new Cuban station on 31 meters (John- etc., to trappers, nurses, mounted police, son, Clarkson, Swanson, Catchim, Kemp, etc., until the middle of the month of Skatzes, Baadsgaard, Peters, Eisler, Smith, May, every Saturday night at 11:30 p.m., Dank, Adams, Curtis, Bower, Trzuskowski, E.S.T. (Fletcher) Naegel, Noda, Frame, Oker, Baker, Win- COH, Havana, Cuba, reported testing on

www.americanradiohistory.com 552 RADIO NEWS FOR MARCH, 1935

sic, the Malkin Conservatory of Music, and the Boston Conservatory of Music. Fac- ulty members from Harvard University, Columbia University, Massachusetts Insti- tute of Technology, Wellesley College, Am- herst College, and the Boston Museum of Fine Arts are providing cultural material. VK3LR Transmissions An official communication from the Post- master General's department at Melbourne, Australia, states that Broadcasting Station 3LR is on the air on week days from 04:15 7jt'E_,RE1:': to 08:30 G.M.T. The station transmits on a frequency of 9850 kc. with a power of 600 watts. The station is now regularly utilized for relaying programs of the Na- tional Broadcasting Service. OFFICI. \I, 1::tyDIG NEW'S CT2AJ Transmissions L1S'7 ENINC ; POST 'OBSERVER An official communication from the sta- i tion director of CT2AJ, at San Miguel, SHORT WAVES j ,, ÌL¡jLIN(JIS Azores, states that they will be on the air every Wednesday and Saturday night from VanL;a.T7G 1935 5 to 7 p.m., E.S.T. At present they are transmitting on 3612 kc. which may be C;:re.:nr.... me U?: CORNER.. RADIO NEW,.: changed to 3500 kc. soon. The power is 50 watts. Announcements are made in Portuguese and the station announcement sounds like "Aqui Say Dois Ah Jhota em Ponta Delgada, Açores." KDKA Transmissions NEW CERTIFICATES FOR OFFICIAL OBSERVERS Here are the new 1935 certificates An official communication from the now being mailed out to Official RADIO NEWS Westinghouse Radio Short -Wave Listening Post Observers who Stations states that are serving this year in helping keep the schedule of station up the high standard of DX news and the Time W8XK is still the -Table for this department same as it has been for the Iast two years, but that a special program was transmitted on Thanksgiving 6220 kc., from 6 -6:30 p.m., irregularly. Day in order to broad- (Malast) German Transmissions cast the Royal Wedding from England. A TGW will soon be on the An official communication change in schedule is to be made in the air on 5940 from the near future. kc., and on 11880 kc., with 200 watts. Reichsrundfunkgesellschaft states that the (Skatzes) German short -wave stations will be on the W2XAD Transmissions DJM, Zeeson, Germany, 49.35 meters air according to the schedule shown in this reported heard the same times month's table. A new station An official communication from the Gen- as DJC. has been eral Electric (Vassallo) added to the group, Station DJQ, which Company states that Station HCK, Quito, Ecuador, 5830 works on 19.63 meters transmitting W2XAD can sometimes be heard on the kc., 51.4 a pro- air at other times than meters, reported heard 8 -11:30 p.m., E.S.T. gram directed to East Asia. the regular pro- (Armstrong) gram. Special tests are conducted with stations in Australia and South America. CGA4, Canada, 9330 kc., heard testing 3 W1XAL Transmissions p.m., E.S.T. (Spaulding) XGW, Shanghai, China, reported heard An official communication from the PCJ Transmissions on 28.70 meters, 10420 kc. (Pasquale) World -Wide Broadcasting Corporation, in An official communication from Philips Boston, CE ?, a station on about 6610 kc., states that short -wave station Radio, at Eindhoven, Holland, states that thought to be Santiago, Chile. (Saldana) W1XAL transmits three educational broad- the old time short -wave station, PCJ, has VK3LR is reported not to be leaving the casts per week. Each broadcast is of ap- resumed its activities. It can be heard on air but rather increasing power. They have proximately two hours' duration beginning the air on 15220 kc., 19.71 meters. During been testing under the call VK3XX and Sundays at .5 p.m. and Tuesdays and the month of December, for instance, the in the future will drop the prefix VK on Thursdays at 7:30 p.m. The programs station was on the air on December 18 the air, using only the call 3LR. They consist of music through the cooperation from 0 to 8 G.M.T., on December 19 from of the New have been heard on the air as early as 12 England Conservatory of Mu- (Continued on page 582) midnight E.S.T. (Sholin) HJIADC, Baranquilla, Colombia, heard LECTURES contacting "Hams" 11 p.m., E.S.T. (Sal - TO CLASSES BY ULTRA SHORT WAVES dana) In a series of experiments at the School of Commerce, New York University, Dean XGBD, Shanghai, China, reported heard Edward Kilduff delivers a lecture to a general science class from his office via on 31.2 meters, 9580 kc. (Pasquale) 5 -meter radio equipment JZI, Japan, heard testing on about 17.3 meters and talking with California. (Baier) CT1AA, Lisbon, Portugal, heard on 31.25 meters, 9600 kc., on Tuesdays and Fri- days, and lately also on Saturdays, 21:30 -00 G.M.T. (Shields, Self, S. J. Emer- son). This station also reported testing on 19.6 meters with songs and music. (Smith) KZRM, Manila, P. I., heard testing on 31.55 meters, 9510 kc. (Pasquale) OCJ, Peru, reported on 15.82 megacycles. (Kemp) I2R0 Transmissions An official communication from the Ente Italiano Audizioni Radiofoniche states that the new short wave station of Prato Smeraldo transmits the American hour from Rome on Monday, Wednesday, and. Friday from 6 to 7:30 p.m., E.S.T., on a wavelength of 49.2 meters.

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 553

WORLD SHORT WAVE TIME -TABLE

Compiled by Laurence M. Cockaday Hours of transmission for the World's Short Wave Broadcast Stations

FILL IN LOCAL TIME 70 17 N 1 2 3 4 5 6 8 9 10 41 M 1 2 3 4 5 6 7 EASTERN STANDARD TIME 8 9 19 20 27 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 GREENWICH MEAN TIME 13 14 15 76 17 18 Wave- length Call Frequency City HOURS OF TRANSMISSION HOURS OF TRANSMISSION Meters Letters Kc Country D 13.9+ W8XK 21540 Pittsburgh, Pa. D D D D O D 13.9+ GSH 21470 Daventry, England 14.2+ LSN 21020 Buenos Aires, Argen. i I I I I I I L 15.2+ IRW 19700 Rome. Italy I I 15.9+ PLE 18830 Bandoeng, Java I /I T. 16.5 LSY 18115 Buenos Aires, Argen. I 16.8+ GSG 17790 Daventry, England I I 16.8+ W3XAL 17780 Bound Brook, N. J. I D D D O D O D P 16.8+ PHI 17775 Huizen, Holland p p PP r 16.8+ DJE 17760 Zeesen, Germany I I I I 17.2+ JIAA? 17380 Kemikawa- Cho.,Jap. 17.3+ W3XL 17300 Bound Brook, N. J. I I I I I I 19.4 PRADO 15440 Riobamba, Ecuador U U U U

19.5 W2XAD 15330 Schenectady. N. V. - O D D 19.6+ CP7 15300 La Paz, Bolivia i l t It 19.6+ DJQ 15283 Zeesen, Germany no 19.6+ W2XE 15270 New York, N. Y. D O D D D 19.6+ FYA 15243 Pontoise, France D D D D D ß 19.6+ PCJ 15220 Huizen, Holland a oil p 19.7 W8XK 15210 Pittsburgh, Pa. I D O D D D D 0 D O D D 8 19.7 DJB 15200 Zeesen, Germany D O XS B 19.8 GSF 15140 Daventry, England D AS 19.8 HVJ 15123 Vatican City I 19.9+ RKI 15040 Moscow, U. S. S. R. L I I 22.0 JYK 13610 Kemikawa -Cho., Jag. 22.3+ TIEP 13420 $an Jose, Costa Rica S S S 22.7+ ORP 13200 Ruysselede, Belg. D D $ 23.3 CNR 12830 Rabat, Morocco C J S 24.2 CT1GO 12396 Paredo, Portugal , MAIM J S 24.8+ CT1CT 12082 Lisbon, Portugal S S S Th XS X5 5 I 5 24.9+ RW59 12000 Moscow, U. S. S. R. S SS 5 25.2 FYA 11900 Pontoise, France D DO DD b D OD 25.2 W8XK 11870 Pittsburgh, Pa. DODD SS AS- D 25.2+ GSE 11860 Daventry, England D p D 1 j 25.3+ W2XE 11830 New York, N. Y. D OD 25.4 I2R0 11810 Rome, Italy II I it 25.4 WIXAL 11790 Boston, Mass. 25.5 DJD 11760 Zeesen, Germany D D D D D D O D D 25.5 GSD 11750 Daventry, England D E I D D D 25.5+ PHI 11730 Huizen, Holland e e I. e p D _ D 25.6 FVA 11720 Pontoise, France 1111411111111411111 P D D D 25.6 CJRX 11720 Winnipeg, Canada I I I D D 26.0 XGR 11530 Shanghai, China D D 27.9+ JVM 10740 Nazaki, Jap. iiiiiO D 28.1 CEC 10670 Santiago, Chile I I I I I I I I 28.1+ JVN 10660 Nazaki, Japan AN 28.3+ FYB 10578 Paris, France AO I I 28.9+ LSX 10350 Buenos Aires, Argen. I I 29.0+ ZFD r 10335 Hamilton, Bermuda I I I 29.0- ORK ' 10330 Ruysselede, Belgium D D D 30.0 KAZ 9990 Manila, P. I. 30.4 EAQ 9860 Madrid, Spain Wi7l11MI 30.4- JYS 9840 Kemikawa -Cho, IJap. iiiiii 30.5+ IRM 9820 Rome, Italy 30.6+ GCW 9790 Rugby, England iiiiNOle 30.7- I2R0 9760 Rome, Italy iiifiiI O D D 31.1+ CT1AA 9600 Lisbon, Portugal AI AI AZ A 31.2+ W3XAU 9590 Philadelphia, Pa. D D O D O D O D S S S S 31.2+ VK2ME 9590 Sydney, Australia S S S SS 31.3 HBL 9580 Geneva, Switzerland Sa Se AF X6 xs xs:xS XS xs AS AS AS 31.3 VK3LR 9580 Lyndhurst, Victoria Australia 31.3 GSC 9575 Daventry, England D D D O D D O OD 31.3+ W1XAZ 9570 Springfield, Mass. O D D D O D O O D O O P 31.3+ VUB 9565 Bombay, India Y Y op II 31.3+ DJA 9560 Zeesen, Germany D O D D ODD D 0 D D D D D D 31.4+ DJN 9540 Zeesen, Germany D O D D 1 0 0 0 S S S I I 31.4+ LKJ1 9540 Jeloy, Norway I I I I, I I I I I D D D 31.4+ W2XAF 9530 Schenectady, N. Y. D O D L. L 31.5 VK3ME 9510 Melbourne, Australia DO D 31.5 GSB 9510 Daventry, England D DO D D D O D 31.5+ PRF5 9505 Rio de Janeiro, Braz. D D I O D 31.7+ COH 9428 Havana, Cuba D Th Th SS_ S D p D 31.8 PLV 9415 Bandoeng, Java D XA I I 32.8 CP6 9120 La Paz, Bolivia I .36 6+ PSK 8185 Rio de Janeiro, Braz' 37.3 CNR - 8035 Rabat, Morocco S S 37.3+ IRS 8020 Rome, Italy I I D D 37.5 HC2JSB 8000 Guayaquil, Ecuador I I I I I I I 38.0+ JYR 7880 Kemikawa -Cho. Jap. 38.3 OA4AC 7820 Lima, Peru 38.4+ HBP 7790 Geneva, Switzerland Sa S8 AF 38 5 YNLF 7 788 Managua, Nicaragua D D D D 40.5+ HJ3ABD 7402 Bogota, Colombia XS XS DD O 40.5+ EA8AB 7403 Teneriffe, C. I. D 41.8 CR6AA 7177 Lobito, Angola, L L L Port. West Africa D 2 O 42.0 HJ4ABB 7138 Manizales, Col. XA S SS XA 2 43 0+ EA4AQ 6976 Madrid, Spain 43.8+ HAS 6840 Budapest, Hungary ; I S I I 6814 San D. R. D 44.0 HIH I Pedro, DD SS D P o p p O D D 44.5+ JVT 6750 Nazaki, Japan o p t I 44.6-1- TIEP 6710 San Jose, Costa Rica I DD T T T T 45.0+ HC2RL 6668 Guayaquil, Ecuador S S 5

www.americanradiohistory.com 55,1 RADIO NEWS FOR MARCH, 1935

(Continued from the Previous Page) Hours of transmission for the World's Short Wave Broadcast Stations

FILL IN LOCAL TIME 8 9 10 11 M I 2 3 4 5 6 7 EASTERN STANDARD TIME 8 9 10 11 N í 2 3 4 5 6 7 01 02 03 04 05 06 07 08 09 10 i1 12 GREENWICH MEAN TIME 13 14 i5 16 17 18 19 20 21 22 23 00 Wave- HOURS OF TRANSMISSION lé th Call Frequency City HOURS OF TRANSMISSION Meters Letters Kc Country Th Th Th 45.3 PRADO 6616 Riobamba, Ecuador 45.3+ RW72 6611 Moscow. U. S. S. R I D D 46.1 HJ5ABD 6504 Cali, Colombia D D D 46.2+ HI4D 6482 San Domingo, D. R. D I 46.6 -{- ! 6447 Bound Col. p 46.6 I Y I W3XL 6425 Bound Brook. N. J. : I I I D O D 47.0+ YV4RC 6375 Caracas, Venez. D D Sa Sa Sa 47.5 HIZ 6315 San Domingo, D. R. XS Xs D 47.8 HJ3ABF 6275 Bogota, Colombia X H 48.4 CT1G0 6198 Paredo, Portugal µr D D I I I 48.4 HI1A 6188 Santiago de Los LIILr4ItxMIMINED_MLll Caballeros, R. - M ES Et `-1 48.7+ HJ2ABA 6150 Tunja, Colombia N D D D 48.7+ Winnipeg, Manitoba D D 487 YV3RC 6150 Caracas, Venezuela D 48.7 O1R1t7t7 VE9CL 6150 Winnipeg, Man. D D D D D 48.8+ W8XK 6140 Pittsburgh, Pa. D D D D 48.9+ ZGE 6130 Kuala Lumpur, o 00 F. M. S. wII i` S:1 48.9+ ZTJ 6122 Johannesburg, Africa {.-11F-43.-flt .! I 49.0+ W2XE 6120 New York. N. Y. 49.0+ 6116 Bandoeng, Java p p 5 49.0+ VDA 6126 Java D D D 49.0+ YV2RC 6112 Caracas, Ven. . MINH . . iii 49.0+ VE9HX 6110 Halifax, N. S. Ff.117.113aiL73107i77PF1t7 O 49.0+ VUC 6109 Calcutta, India î14I L'Sa - AL- 49.1+ W3XAL 6100 Bound Brook, N. J. 11111111M1111111116W/LVIIr /( ALTIMA - 49.1+ W9XF 6100 Chicago, Ill. 1111111I a [ E % X5 X5 - 49.1+ VE9GW 6096 Bowmanville, Can. 111M1111011RIIIIAIMWAIMIIMEMZIFII 49.2+ I 6085 Rome, Italy ID D I 49.3+ CPS 6080 La Paz, Bolivia D D D 49.3+ W9XAA 6080 Chicago, Ill. K K 49.3+ CQN 6073 Macao, Asia MMMMMN-IM D 49.3+ OER2 6072 Vienna, Austria D D rThilF7auo[-zii F'1IMI-M7:Stli - 49.3+ VE9CS 6070 Vancouver, B. C. =1MICIIIIWill IF-y1I7 IMMIll 49.4+ VQ7LO 6060 Nairobi, Kenya, Afr E40:1J lt-11=11= womm.T ttmI! ' 49.4+ W8XAL 6060 Cincinnati, Ohio Y1I7f]r1 tilf7 D D D 49.4+ W3XAU 6060 Philadelphia, Pa. IMMMMMMM=IMMMMI 49.4+ OXY 6060 Skamlebaek, Den. IINIMMí =7]I0..Ml 49.5 GSA 6050 Daventry, England DD D D O D D D D D 49.6+ HJ1ABG 6042 Barranquilla, Col. D D E E 49.6+ W1XAL 6040 Boston, Mass. D S S E D D D 49.7+ HP5B 6030 Panama City, Pan. D D D D D O 49.8 DJC 6020 Zees n, Germany D D D D D O D D s S AA, Ale N NN 49.8+ ZHI 6012 Singapore, Malaya N S S AA I I I Sa Sa - 49.8+ COC 6010 Havana. Cuba DO D P I I D O D D -p 49.8+ XEBT 6010 Mexico City, Mex. D D D D D D D D D D Sa 49.9+ VE9DN 6005 Montreal, Quebec D D -D Sa. Sa - $ 49.9+ HIX 6000 San Domingo, D. R. DD I )(G 49.9+ RW59 6000 Moscow, U. S. S. R. OD B I S D 49.9+ FIQA 6000 Tananarive, Madag. XS L XS AS X$ AS 50.1 TGX 5984 Guatemala City XS X$ XS XS --- S 50.2+ HVJ 5969 Vatican City D G G G 50.6+ HJ4ABE 5860 Medellin, Colombia XS X, T G G D D D - 51.2+ YV5RMO 5850 Maracaibo, Venez, D DO D pp 51.4+ HJ2ABC 5824 Cucuta. Colombia D DO I I I I - 51.9 OAX4D 5820 Lima, Peru D D I I 51.9+ TIX 5795 San Jose. Costa Rica 52.0 TGTH Almatices, San Jose Costa Rica O D D 52.9+ XQAJ 5660 Shanghai, China I j I 64.5+ HC2EP 4650 Guayaquil, Ecuador 69.4 G6RX 4320 Rugby, England IT 69.5 YNLE 4316 Managua, Nicaragua I D D D D D O 70.2 RW15 4273 Khabarovsk, Siberia D D XM XM î3+í XM 73.0 HCJB 4107 Quito, Ecuador X XM 80.0 CT1CT 3750 Lisbon, Portugal S 8o o+ Radio LL 3 700 Paris, France 8.3.0 CT2AJ 3612 San Miguel, Azores WS WS 84.6+ CR7AA 3543 Lourenzo Marques, AG AC AC

I Mozambique KEY TO TIME TABLE SYMBOLS A- Sunday Winter only P- Except Tuesday, Wednesday, Summer only AE- Except Monday, Wednesday, Friday B- Sunday, 7.1fonday, Wednesday, Frid 0-Except Tuesday, Wednesday AF- Saturday irregularly C- Monday, Wednesday, Friday _R- Thursday, Friday, Saturday AG- Tuesday, Sunday D -Daily at hours indicated S- Sunday AFI-Time at 7 :30 G. AI. T. E- Tuesday, Thursday T- Tuesday AI- Tuesday, Friday, Saturday F Friday TH--Thursday SA- Saturday G- Tuesday, Thursday, Saturday L -Sunday, Summer only XA- Except Saturday, Sunday H \VednesrIa -, Friday, Sunday -Wednesday-, Sunday XE- Except Friday I- Irregularly \W- Wednesday- XG- Except Tuesday, Thursday, Saturday J-- Thursday, Saturday 1- Monday, Wednesday, Saturday X\I- Except Monday IC- Monday. Friday 7 Tuesclay, Friday XS- Except Sunday L- Wednesday, Saturday AA- Saturday, Sunday XSa- Except Saturday DI- Monday AB- Except Monday, Tuesday, Wednesday XT- Except Tuesday N- Monday, Wednesday. Thursday AC-Monday, Tuesday, Saturday XTh- Except Thursday 0-Tuesday, Friday, Sunday AD -Time at 20 G.M.T. X\V- Except Wednesday

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 555

...but because we PROVE it in this sensational way! You must be satisfied that the SCOTT All -Wave XV is truly "The World's Finest All -Wave Receiver." To convince you, we make this offer: Get a SCOTT All -Wave XV from the laboratory where it is custom built. Install it in your home anywhere in U. S. A. and test it competitively against any other radio in the world during a 30 -day trial period. If it does not bring in more stations, from greater distances, with more volume and better tone, on both the short waves and JO" g g the broadcast band, it may be returned used in the construction of the SCOTT All -Wave XV The reputation of this receiver has (except tubes) is guaran- been won in the toughest kind of teed for five years. The service to the most discriminating Console illustrated is in the Waverley - one type of buyers. Scott capability of a complete line distance- getting-in dependability -in of beautiful Scott gloriously rich, true tone ... comes from Cabinets. finer methods of building- custom -construction in which every operation is held to the closest limitations known in radio manufacture. E. H. SCOTT RADIO LABORATORIES, INC. 4440 Ravenswood Avenue, Dept. 5C5, Chicago, Illinois Inquiries may be addressed direct to the laboratories, or the foreign office nearest you. AZORES, Rua da Misericordia, 2, 4, 6, Ponta Delgada; BRITISH WEST INDIES, 10 -12 Port Royal St., Kingston, Jamaica; COLOMBIA, Apartado 621, Bogota; ENGLAND, Ethelburga House, 91 -93 Bishopsgate, London; GREECE, 8 Rue Canaris,Athenes;MEXICO, Independencia 100, Mexico City, D. F. ; Calle Diaz Miron 40, Ote. Tampico, Tamps., Mexico; NEW ZEALAND, 9 -11 Pacific Bldg., Auckland; PERU, Casilla 1915, Lima; PUERTO RICO, 7 Jefferson St., San Three; SPAIN, Alameda Recalde 46, Bilbao; Paz 14, Valencia; SOUTH AFRICA, Beckett's Bldg., President St., Johannesburg; STRAITS SETTLEMENT, 96 N. Bridge Rd., Singapore; VENEZUELA, Caracas. xn cour E. H. Scott Radio Laboratories, Inc. 4440 Ravenswood Ave., Dept. 5C5, Chicago, Ill. Please send full particulars about the Scott All -Wave XV, including technical data, rscoîî performance proofs, etc., and details of your 30 -day trial offer anywhere in the U. S. A. Name Auwnve x Address City State

www.americanradiohistory.com 556 RADIO NEWS FOR MARCH, 1935

' New Type of CARBON RESISTOR

After extensive research the chemists have developed a new type of carbon resistor which offers some attractive advantages for radio applications

THE innocent looking carbon re- CARE Iii COLOR CODING developed by Lynch Mfg. Co. which sistor has been subjected to in- Great care is fed in clearly coding consists of a more uniform mass and tensive study and painstaking re- each of these new resistors to avoid hence has an even distribution of cur- search in order to improve its quality. confusion in determining values rent density. The new resistor con- In general, there are two kinds of car- sists of a basic resistance material-in- bon resistors. The first is the carbon stead of insulating material -and an- coated type and the second is the well ally used today and consists of a mix- other resistance material of higher con- known carbon composition moulded ture of some conducting material, car- ductivity. The two are mixed in va- type. bon and an insulating material. This rious proportions to make the different The carbon coated type consists of a mixture is moulded under relatively resistance values. The mixture is glass tube or rod with a thin film of low pressure. Mixing several ingre- formed into rods under very high pres- conducting material on its external sur- dients may make the composition uni- sure. face. In order 'to make the various re- form to the naked eye, but in many The uniformity of the material in- sistance values, the thickness of this cases when a sufficiently powerful mi- sures that the entire cross -section car- film is varied but at most it is extremely croscope is used, the mixture will still ries current and the high pressure elimi- thin. This delicate exposed film is of consist of three distinct substances each nates the point contacts. Such a resis- course liable to be damaged easily and of which is present in the form of "peb- tor has a uniform current distribution also, because the cross -sectional area is bles." These pebbles touch each other and the tests do not show any "light so small, the current density is small, at one point generally, and besides, the points" as they did in the old type. A causing overheating. mass is porous, having comparatively microphotograph (SO power) of this The second type is the most gener- large "open spaces." This can be seen new type (Continued on page 581) in the microphotograph of Figure 1. The picture was taken through a micro- AN ORDINARY RESISTOR scope of 80 power and shows the cross - THE NEW RESISTOR Figure 1. A cross section photographed section of an ordinary carbon resistor. Figure 2. Photographed under the through an 80- power microscope. Note The foregoing should make plain that same enlargement as Figure 1, the the coarse, porous appearance in con- the usual carbon resistor is not uniform close -grained texture of the new re- trast to that of Figure 2 in composition. At certain places there sistors is evident may be more conducting material than at others and the distribution of current will also be irregular. So it might happen that nearly all the current has to pass through a comparatively small part of the cross -sectional area and in any case it must pass through the point - contacts between individual particles with resulting high current density at these points. This theory has been checked experimentally by placing such a resistor under a higher load than its rating and it was observed by the use of microscopes that some points became hot enough to emit light. Under these conditions it is likely that the resistance value of the resistor will vary. The presence of relatively large voids also causes variations of resistance because the unit will absorb moisture. Furthermore, mechanical strains will have the same effect. A new type of carbon resistor was

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 557

QA New KACK and PANEL AMYLIl'I ER (Pre -Amplifier Unit)

The pre -amplifier described here offers relatively high gain with substantially complete freedom from hum. It is operated from the power supply of the main amplifier and is adaptable to either rack or table mounting B. J. Montyn Part Two

IAST month the main amplifier and volts; Amplification factor, 20; mutual power pack of this public address conductance, 2000 micromhos; ; plate system were discussed. This month resistance, 10,500 ohms; load resist- THE COMPLETE AMPLIFIER the description is completed by the addi- ance, 15,000 ohms; power output, 300 tion of a -amplifier. milliwatts. The top panel is the pre -amplifier and pre the third panel down is the main am- From all reports received, many Great care has been taken to minimize plifier. The power supply panel is at readers are having difficulty with pre - noises and hum in this unit. Two extra the bottom of the rack. Below are amplifiers. The writer has listened to filter sections have been placed in the shown close -ups of the pre -amplifier this preamplifier connected ahead of power supply and the tube sockets are unit which is discussed in this article the main amplifier, using phones and mounted in sockets using non- micro- having everything turned up full. The phonic springs. The pre -amplifier is, hum is noticeable, of course, but re- of course, completely shielded and so CRYSTAL markably low. The total gain of the are all the cables leading to it. MICROPHONE two amplifiers is 130 db. A limit of gain The input transformer has a tapped must be reached, dué to thermal agita- primary with an impedance of 500 tion. ohms with provisions to accommodate 5 The pre -amplifier consists of two 333, 200, 125 and 50 ohms. Nearly all M EG .04 transformer coupled stages using 77 or velocity microphones now have a trans- MFD 6C6 tubes as triodes as shown in the former in the base which will match the circuit of Figure 1. It has been found input of the preamplifier. Those who SHIELDED LOW .5 that connecting the screen and sup- wish to use a crystal microphone should CAPACITY 1200 MFD pressor of a 77 or 6C6 CABLE FROM s OHMS to the plate con- employ the resistance -coupled input as MICROPHONE verts it into an efficient triode. This con- in 2. 400,000 shown Figure OHM S nection provides a mu of 20 and a rela- The output transformer accommo- FIG.2 tively low plate resistance. The char- dates 500, 200, and 50 ohm lines. acteristics for this connection were The construction of the preamplifier measured in the laboratory of the Con- is similar to that of the main amplifier. necticut State College and are given It can be had for rack -mounting or for herewith: Plate voltage, 250 volts; table- mounting, and the same chassis plate current, 7 volts; grid voltage, -8 serves for both. (Continued on page 586)

THE PRE -AMPLIFIER CIRCUIT

T 77 oR 6C6 T2 77 OR 6C6 T3 a ó 1 C1 o .5 C2 Ô C4 a MED. 5 Ñ .5 X X MFD. MFD. o 400 V. 400V. 400v

R4 R5 RS.,- 400,000 4200 40,000 400,000 5 200 40,000 OHMS OHMS OHMS OHMS MFD. OHMS OH-IMS W 1/2 -'r- 2W. 2W. Y2 W. 400V 2W. 2W. 1 4 5, 000 C7, 1 4 M F D. C8 - . OHMS 200 AND i 2W. V. C9 ARE 8+ ÓÒ 6ZS6Ò X IN 6 POWER R7 L4 C8i 6.3 V.A.0 SUPPLY 46 4 + C6 I y 1'^T MFD. C7 MFD MED. C5 T C 9 450V.'T 400VT 400VT X FIG..1 g-o

www.americanradiohistory.com 558 RADIO NEWS FOR MARCH, 1935 FIRST AID TO INVENTORS SM4LING your INVENTION

This is the fifth of the series of articles written exclusively for RADIO NEWS readers explaining little - known facts about patents. The subject this month is "How to Obtain Financial Recognition on Your Invention" YOUR PATENT IS FILED HERE Some of the cabinets for filing patents are shown in these E. E. Free, Ph.D. balconies of the Patent Office. But that does not get you any return for your work. fl patent must be sold and Part Five used to bring a return to the inventor

PROBLEMS discussed in previous ar- tent to which the invention is used. using an invention himself or of financ- ticles of this series, protecting your The third source of cash from an in- ing a company inventor's rights, embodying to do so will be discussed these rights vention is to use it yourself in some next month. in a patent and the rest of them, mean profitable nothing in themselves. They merely are way, and the fourth is to Outright sale of an invention is the preliminaries to the last and most im- raise money, organize a company and simplest and in many ways the best portant step, which is to turn the patent then use the invention for the profit of method of making money from an in- into money! that company's stockholders. This vention, if it is possible at a price upon article discusses the first two of these which seller and buyer can agree. A WITH rare exceptions there are possibilities. The inventor's chances of sale involves no possibility of later ar- only four ways of realizing a guments about mutual WHAT IS THIS PATENT WORTH? rights, for there profit out of an invention. One are none. All rights pass at once to the is by outright sale of the invention for The newest invention of the German buyer. There are no complicated con- a sum of money. The second is by scientist, Carl von Dreger, that he tracts to be drawn and interpreted. royalty, which means that the pur- calls a physiological instrument for The transaction is over and done with agrees testing musicians, may be worth a chaser to pay the inventor speci- fortune, unless at once, like a purchase over the fied but it is sold and comes sums for each article manufac- into wide usage it will not bring a counter of a store. tured under the invention, or some very large financial return to the The difficulty is that outright sale other payment proportional to the ex- inventor seldom is possible. In the nature o_ f the case, the commercial value of a new invention usually is unproved and problematical. The inventor naturally considers it immensely valuable. Pros- pective buyers, on the other hand, are more likely to remember the many slips which happen between financial cups and lips and to be unwilling to pay a cash sum which the seller considers adequate. Even if the inventor sets his price for an invention on the basis of what it cost him to develop it, the same difficulty is likely to arise. If the invention is really valuable it will be worth many times its cost of development. If it meets no commercial success its value may not equal even a fraction of these costs. Sometimes the probable commercial value can be assessed with some accuracy, especially if the invention is one for which a clearly determined market already exists and if its practical working and its engineering features have been established by sufficient tests. In my experience this very

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 559 seldom is the case. Long and expensive extent to which the invention is used. commercial trials usually are necessary Such licenses may be either exclusive before anybody can say with certainty to one purchaser or may be non- exclu- whether an invention is worth a million sive, permitting the inventor to make dollars, a thousand dollars, or nothing. similar licenses with other purchasers Think of de Forest's invention of the if he can and if he so desires. three -element vacuum tube. When that Details of these three general plans, device was invented radio broadcasting outright sale, royalty and license, may was undreamt of. Need for a telephone be almost as varied as the inventions repeater was appreciated but there was they cover. An invention protected by no assurance that the vacuum tube a patent is legally a piece of property, would be useful for this purpose; in- like a diamond ring or a house and lot. deed, the first vacuum tubes developed It may be sold, mortgaged, rented, by Dr. de Forest were not good re- given away or lent, much as can be peaters. Even aside from legal ques- done with any other kind of property. tions of breadth and validity, who could AN IMPORTANT INVENTION In all such transactions the inventor have said what the vacuum tube patent The instruments in back of this panel will be well advised to have the aid and really was worth? It then was valued, are proving their worth as important advice of a competent lawyer; not I understand, at $40,000. It turned out and remunerative inventions. All the necessarily an expert patent lawyer but to be worth many times that sum. It pilot has to do in this plane is to press a general lawyer familiar with business might have turned out to be worth al- buttons for the plane's operation. It dealings. It is impossible to say cate- most nothing. will take off to the elevation you pick gorically that either outright sale, Just as inventors as a class are too out on the board, will keep to a set royalty or license is the best way to likely to suspect everyone of trying to course, will straighten out of a wind individual patent into cash. pocket, and in fact will completely fly turn any steal their inventions, so it has been my the plane Everything depends on the circum- experience that they tend to regard all stances. It is my belief, however, that business men as crooks trying to buy some royalty or other basis of making their inventions for a fraction of the wait for his returns until the inven- the total payment depend on the in- real value and to make enormous for- tion has proved its utility and its money vention's commercial value as later de- tunes by doing so. This is nonsensical. value. veloped is likely to be fairer and more Naturally, everyone buying an inven- A royalty contract may be on either satisfactory all around than a basis of tion wants to get it for as little money of two different bases; what might be outright sale. as possible. The inventor himself, if he called a sale basis and what is called a There exists, however, one serious is even moderately sensible, does ex- license basis. The first is legally simi- objection to many royalty contracts, actly the same thing with everything lar to an outright sale. Ownership of the possibility that the invention may he buys, from the food that he eats to the invention passes to the purchaser, be purchased not with any idea of us- the parts he needs to work out new in- who merely pays for it slowly and in ing it but with the idea of preventing ventions. In actuality, I am convinced proportion to its use and value instead anyone from using it. This sometimes that the price at which inventions are of paying immediately. The alternative is called "pocketing" an invention. sold averages too high rather than too license arrangement leaves the owner- Suppose that an independent inventor low. For every patent, like the vacuum ship of the patent with the inventor. has perfected something which might tube one, which is sold at what later The purchaser merely obtains a license replace a device sold or used by a large proves to be below its real value, there to use the invention, under specified and powerful business organization. It certainly are hundreds, probably thou- terms and conditions and for specified may be good business for that organiza- sands, which are sold for much . more payments, usually depending upon the tion to buy the patent with the idea of than they later turn out to be worth. keeping it off the market, so that the This is not saying to the individual existing business situation will not be inventor that he must sell his inven- WHOSE INVENTION IS THIS? upset. Suppose, for example, that some tion "cheap." What it does say is that one invented an entirely new and is a new radio -receiving set for is an unfair and Here radio waves. outright sale usually use on Washington's Police motor- cheaper way of producing unsatisfactory way to dispose of an cycles. The device certainly shows It might be well worth -while for ex- untried invention, both for the seller originality and possibly a number of in- isting radio interests to buy this pa- and for the buyer. Both necessarily ventions were employed in its make -up tent, put it (Continued on page 588) must take gamblers' chances. One or the other often loses money or potential profits, and feels disgruntled. That is why the royalty contract, with all its disadvantages, usually is a fairer way to transfer an inventor's rights. The simplest royalty contract provides merely that the buyer shall have the right to use the invention (exclusively or otherwise as may be specified) and shall pay to the inventor a certain sum of money for every one of the invented articles that is made. Other royalty contracts may specify payment of a percentage of the sale price, a percentage of profits, or sums fixed in still other ways. The essence of the plan is merely that the payment to the inventor is made to depend upon the value which the invention proves to have for the buyer, not upon the value which anyone imagines that the invention will have. Naturally, the total price which a buyer will give for an invention on a royalty basis is much larger than on a basis of outright sale. On the other hand, the inventor gets little or no immediate cash, but must

www.americanradiohistory.com 560 RADIO NEWS FOR MARCH, 1935 RADIO NEWS SERVICE INSTRUMENTS -No. 4

QA- 100-22,000 kc. SIGNAL GENERATOR This article provides the constructional details of a new service unit developed in the RADIO NEWS Laboratory. The schematic diagram appeared last month John H. Potts Part Two

IN spite of its compactness, the con- dipped in coil dope and the entire coil struction of the signal generator de- thoroughly impregnated with this same scribed in last month's issue of moisture -resistant dope. The coils RADIO NEws will not be found difficult should then be assembled on the mount- if the assembly procedure to be outlined ing panel which is constructed accord- is carefully followed. It is recom- ing to the specifications of figure 3, The mended that the cabinet and oscillator individual coil assemblies have their ter- coils be purchased unless the construc- minals brought out to thin bakelite ter- tor is equipped to do this type of work. minal panels for convenience in wiring. For those who wish to make the cab- Flat head brass wood screws are used to inet, specifications are given in Figure 1. fasten the dowel forms to the assembly The flange of the cabinet and the por- panel. The complete assembly is shown tion of the back of the front panel mak- in figure 4. ing contact with the flange should be The line filter coils may be conveni- gone over with emery cloth to remove ently constructed by following the all traces of enamel and assure good specifications shown in Figure 5. The SUB-PANEL LAYOUT electrical contact when the instrument mounting for these coils consists of thin is assembled. sheet copper with partitions soldered to - ; 2%R j`-!1 z/e ' + s The oscillator coils are wound in im- the mounting to shield the coils from ----;_a , Im I pregnated wooden dowels according to each other. The can in which the filter 23'a--' 9J,__D0.iLi-ó- /e the specifications given in Figure 2. coil assembly is installed may consist of DRILL 4 O* -5/J2 f 1 116 3,6 l' Coil number 1 must be carefully con- a discarded shield from an i.f. trans- iola ! 6 2 HIOÉ MOLE. wIRE 5 structed if oscillation over the entire former. 5 -If6 tuning range is to be achieved. The The oscillator coil assembly and the 2 tickler winding must start as closely as line filter apparatus should not be HOLE 1 16 /9 o 1. possible to the secondary winding. After mounted on the sub -panel until the 3 I-..l4' '532DRILL 3 ROLES ¡L, n !' construction, the leads should be another parts have been assembled and I ,5 e chored in place with strips of fabric in FIG.4C thin wired to the circuit. This method of

FRONT PANEL LAYOUT . TYPE A TYPE B F 1014 746 DRILL % 532 Lops, DR/ILL 4/6 5/32' DRILL,_ ',kb DRILL DRILL SIB' -1-6. I DRILL 3/e BAKELITE B+ ' 24 DRILL FI G.2 NOTE-ADJUSTABLE COUPLING DRILL 72 5/32 -ko m DRILL r COIL 4 DRILL w NO. 2 3 4 5 6' SIZE 36 ENAM 36ENAM 36ENAM 34ENAM 34ENAM. NOTEA PLATE TURNS 42 48 45 75 150 NOTEA I 7/16 DRILL 3" SIZE 2$ O.C.C. 28 D.C.G. SOENAM 30 SSE SO SSE NOTE A RILL N GRID TURNS 5 20 65 440 300 NOTEA

2 DRILL 22 9.7 3.5 4580 K.C. 600 KC. 250 KC 4sNlm RANGE TO TO TO TO TO TO 9 MC. 2.9 MC. 4.49 MC. 570 KC. 220 KC. 400 KG. DRILL x DRILLL koi`3/$DRILL FORM OF WINDING A A A B B B SPACEWINDINGSEEN Tp V4 6 T046 THAN 4 X32 4/32 8 4B NOTE A- DATA ON MANUFACTURED COIL NOT AVAILABLE AT TIME OF WRITING; CAN BE MADE FROM 445 KC. I.F. TRANS. COIL

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 561 assembly will leave plenty of room to work around in. After the panel and N0.5 N0.2 N0.1 sub -panel wiring have been completed as far as possible, the oscillator coil assembly may be temporarily mounted in position and a few bus -bar leads, insulated with spaghetti tubing. soldered to the range switch. These leads will serve to support the gang switch which may now be removed from the panel and the wiring from the coil assembly to the switch terminals completed without difficulty. When this is done, the switch and coil assembly may be installed as a unit in the signal generator circuit. The line filter assembly is handled in like manner. When the line filter is per- manently installed care should be taken that its shield does not touch the signal generator shield. The line filter condensers should be installed last of all. The output tip jacks are both carefully insulated from the panel. The lead from C11 to the moving arm of the attenuator is shielded and the shielding is insulated from the signal generator, which may be done by taping it or minia- with a large diameter piece of insulat- Incidentally, these are the only COIL MOUNTING PANEL to the writer's ing tubing. This shielding is connected ture neon lamps available, 3Z DRILL knowledge that are sufficiently stable 2 NOLE5 3/4-.4-r/8- 4`I 1 , to J2. 4G in electrical organs <' The variable condenser is mounted for use experimental 2 with the isolantite stator support per- and other audio oscillator applications. T -4% pendicular to the sub -panel to afford These lamps. known as the type room for the pilot light assembly. The may be obtained by individuals or deal - named con- stator lead to Sw 3 should be as short ers direct from the above o (I)* as possible and passes to the switch cern. wiring have through a hole in the sub -panel. The When the assembly and usual single -hole mounting is rein- been completed, the oscillator coils may I- 33'4' DRILL AND COUNTERSINK- -- * HOLES checked for operation forced by drilling and tapping the rotor be conveniently TO FIT NO. 8 W000 SCREW by connecting a 1 ma. meter in series support so that a 6/32 screw may be USED. with the grid -leak, R 13. The reading y8 BAKELITE passed through the front panel and a DRILL secured will be proportional to the HOLES 4 AND 2 ARE %2" spacing bushing to the condenser frame FIG.3 and thereby relieve strain on the single - strength of oscillation. A less sensitive hole mounting, which otherwise might method is to connect a 5 ma, meter in loosen causing the condenser to shift series with the output plate circuit and in current when position and ruin the calibration. note the change plate COIL MOUNTING PANEL The modulation frequency control is the variable condenser stator is touched mounted at the right above the filter with a moistened finger. Since the choke and the percentage modulation change produced at the low frequency control in a corresponding position at end of coil No. 1 is very small, this lat- the left. The associated condensers and ter method, though more convenient is resistors are wired in as closely as pos- not quite as reliable. If oscillation is sible to these controls. The condenser not secured on all coil bands. the connections to either grid or plate should leads from the variable condenser rotor B+ should be kept as short as possible. C18 be reversed. Do not reverse both wind- wound in the should be installed beneath the sub - ings. All coils must be panel, close to the oscillator coil as- same direction. Otherwise oscillation sembly, likewise the voltage divider re- may be secured over a portion of the sistors, R8 and R9. hand only, or none at all. Coils must FIG.4 The neon tube employed as the modu- be assembled in the rotation shown in Figure 4 or absorption effects will be lator is a special miniature type made NUMBERS REFER TO COIL RANGES indicated by abrupt peaks in the curves. ALL TERMINALS MARKED 5+ TO BE JOINED by the General Electric Vapor Lamp .. ., ., F . " Company, Hoboken, N. J. It is sup- They should (Continued on page 584) plied without a base and is wired directly into the circuit by its pigtail lead is indicated by LINE FILTER COILS leads. The positive COIL LEADS a red dot. The lamp is located beside the modulation frequency control potentiometer, Rl. tIN This lamp should not be confused with the miniature neon lamps (known THIS as the watt type) generally available. END / OPEN -N- These standard lamps will not work satisfactorily as audio -frequency oscillators because they are not sufficiently stable 13 in their frequency characteristics. Also SHIELD FOR LINE FILTER. BAKELIT the presence of a base on a lamp of this 2 %4 COILS MOUNTING type introduces leakage, and it is for STRIP FOR. ALL CO LS WOUND WITH 400 TURNS SHIELD that reason that the special type speci- NO 26 DSC (SCRAMB!.E-WOUND) FIG.5 fied here is supplied without a base.

www.americanradiohistory.com 562 RADIO NEWS FOR MARCH, 1935 RADIO

AIRCRAFT (Servicing Accessories) Henry W. Roberts Part Four

bench, starting at slow speed (not over 500 r.p.m.), and gradually speed- IN the last installment of this series GOOD SERVICE IS ESSENTIAL ing up during the last fifteen minutes the author dealt with the servicing of until the rated speed is reached; then aircraft In aviation radio no slip -shod service radio receivers and transmitters. methods can reinstall on the engine, taking Now he discusses be tolerated, for the safety care to checking over genera- of the passengers and pilot, see that the generator drive is tors and other accessory jobs. today, rest shaft mainly with perfectly working appa- properly aligned, the flexible coupling ratus secured, and all bolts WITH the "safetied" with set proper out of the wire. way from a service standpoint Air -driven generators, the next job is to inspect although more the disassembled, washed in gasoline, and expensive and less reliable, auxiliary equipment, starting with the are still oc- dried before reassembly. In reassem- casionally found. The servicing pro- generator. Generators, while strictly bling, care should be taken that the cedure remains the same, except for speaking a part of the engine, are usu- brushes are "seated" properly on the the very troublesome ally left to be item of the serviced by the radio commutators, making full contact along single -bladed air propeller. mechanics; and since generator servic- Check the their entire length. If it is necessary to generator shaft carefully against side ing is seldom encountered in ordinary reseat the brushes, insert a strip of play in all positions of the blade, radio work, we will describe briefly the sandpaper as between the commutator this may unbalance the propeller to more essential features of the operation. and the brush, and draw the sandpaper such an extent that it As the brushes wear will break (or down, fine car- against the direction of rotation of the break the shaft). See bon dust accumulates that the retain- inside the gen- armature, repeating the operation un- ing lock -nut on the propeller erator, mixes with lubricant, shaft is and forms til the brush is seated properly. The tight, or the propeller may back a sticky paste which interferes with up the sanded side is held against the brush; shaft and fly off. The operation, particularly speed of the with the move- never sandpaper generator commuta- propeller may be increased ment of the brushes. These by turning deposits tors (unless extremely rough), nor re- the adjustment screw in must be cleaned the propeller out, and the brushes move the dark surface film normally boss, opposite the blade root, found in the on the commutator surfaces. Be clockwise direction; or reduced, by sure to clean out or blow out all sand turning the screw anti -clockwise. The particles. Chipped or worn brushes armature should rotate without hum- should be replaced. ming at the cruising speed of Repack the air- all bearings with high melt- plane; reduce the generator r.p.m. if ing -point grease, oil where necessary, humming develops. Damaged blades and replace worn oil -seal washers. Give can sometimes be straightened out in the generator an hour's run -in on a the shop, but unless the damage is very slight, it is better to install a new blade; it is still better to install an en- POWER GENERATORS gine- driven generator. At the left is shown the wind -driven The generator control box will sel- electric generator for use on aircraft. dom cause any trouble, Below is the newer but its interior and tiny but pow- must be maintained scrupulously erful type of generator preferred for clean, modern aviation radio installations. to prevent oxidation of contacts. When .ds brushes wear down, as bearings rough, the contacts should be smoothed need oiling, the serviceman must make off, using a piece of canvas or very the necessary checks and repairs fine crocus cloth. Do not change the factory setting of the cut -out, or increase the charging rate. The battery requires more frequent inspection than every 20 hours, and is normally cared for by the ship's me- chanic; nevertheless, satisfy yourself that it is being properly maintained, that the spill -proof caps are tight, and that none of the acid found its way into the shielding box containing the battery. The dynamotor will not require any servicing except lubrication, and occa- sional repacking of bearings. How- ever, if the (Continued on page 579)

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 563 SUNSET TO SUNRISE with FOREIGN DX R. H. Tomlinson Part Two

before 1:00 a. m., well heard. Their announcements sound due to interference like this : "Ach- toong, here vest -doy- from locals. tcher Roondfoonk." Transmissions be- Slightly better gin at 12 :30 a. m., but due to inter- signals can be ob- ference from WEAF, it is well to wait tained by using di- until after 1. Berlin on 841 starting at rective antennas, 12 :30 a. m. with gym class is perhaps but with the mod- the easiest of the German to identify. ern supers I can Their announcements are "Ach- toong, find little important here Bear- leen ". Between announce- advantage gained ments you may hear a few notes from through their use. a music box. Budapest is another well Successful broad- heard here. Transmissions begin at cast band DX'ing 12 :45 a. m. and can be identified by the to the extent men- lady announcing, "Allo, here Budapest ". HAMBURG, 904 KC., 100 KW. tioned, depends on Budapest leaves the air at 1:15 a. m. 1140, is This is one of the stations logged by the author. The several factors. You Turin Italy, IiTO, on the best 450 -foot tower is unique in that it is built entirely of wood must know where of the Italians, with announcements to look for the sta- starting off something like this, "e -yahh tions, what time rah -de -o nord e- tal -eya Tor -ino ". IN the previous article the reception they start transmission and how they The easiest of all Europeans to iden- of European broadcast -band sta- are identified. If a few words of the tify and the best heard, is Poste Pari- tions was discussed. Now, what language of each country is not known, sien in Paris, on 959 kc. Their trans- about Australia? Here we find a dif- then you must at least know what their mission begins at 2:10 a. m. each week ferent story. Both short and long announcements sound like. For the day. At 2:10 sharp, you will first wave DX'ers must rise at 5:00 a. m. to benefit of those wishing to try their hear a bugle blowing reveille. This is log these stations, so I am up again luck on long wave DX'ing, I will list repeated twice, with drums coming in after two hours sleep. I then proceed a few of the better heard Europeans, on the third time. Our announcement to tune in more Australians on the regu- giving the time they start and how they follows, always by a man: "Allo, allo, lar broadcast band than the short wave announce. Poste Pare -ree- sun." One more of the listener can hope to log. Space doesn't At midnight tune to 904 kc. and wait Europeans and we will have finished permit a description of all these nor for Hamburg to begin. A man will an- with them. This is Prague on 638 kc., was any attempt made to copy any of nounce first, "Ach- toong, ach- toong, who comes on at midnight. Their an- the transmissions. My aim at this time here Hamboerg." This station can be nouncements are simply: "Here Praha ". was to log and identify as many as heard until as late as 2:30 a.m. Col- For those wishing South American possible. ogne, Germany on 658 kc. is another reception a (Continued on page 586) At 5 :02 a. m. my first station was 2BL, Sydney on 855 kc., giving time an- 740 KC., 100 KW. nouncements as 5 minutes after 8 p. m., AN INDOOR STUDIO AT MUNICH, Sydney time. Then in rapid order, be- Broadcasting House, Munich, has five studios, the largest of which is shown here tween 5:05 and 6:00 a. m. the following were logged and identified: Rock- hampton, 4RK, on 910 kc., Brisbane 4QG 760 kc., Sydney 2FC 665 kc., Wellington N. Z. 2YA on 570 kc, Perth 6WF on 690 kc., Crystalbrook 5CK on 635, Corowa 2C0 on 560, Sydney 2GB on 949, and Adelaide 5CL on 730. Christchurch 3YA on 720 is the second from New Zealand. Another in Ade- laide 5DN on 960, one more in Sydney, 2UE on 1025. Then to top off the morning's reception I proceeded to tune in 4BC on 1145 kc., in Brisbane, using a power of 800 watts. My total is one dozen Australians and two in New Zealand. Is there any short wave DX'er that can find fault with that log? Is it necessary for the listener to have special receivers and aerials for this long wave reception? Absolutely not. Two standard receivers were used in tuning all the stations I mention, one a late model super and the other a five year old t.r.f. 8 tuber. A super is of course needed to receive Europeans

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935

Official RADIO NEWS Broad- cast Band Listening Post

Observers . United States California: Randolph Hunt, Warren E. Winkley Connecticut: Fred Burleigh, James A. Dunigan, R. L. Pelkey Illinois: Herbert H. Diedrich, Ray E. Everly, D. Floyd Smith Indiana: E.' R. Roberts Iowa: Lee F. Blodgett, Ernest Byers Maine: Steadman O. Fountain Maryland : William Rank, Henry Wil- kinson, Jr. Massachusetts : William W. Beal, Jr., Russell Foss, Evan B. Roberts Michigan : John DeMyer, Howard W. Eck Minnesota: F. L. Biss THE DX CORNER Missouri : T. E. Gootee, C. H. Long Montana : R. W. Schofield (For Broadcast Waves) New Jersey: Jack B. Schneider, Alan B. Walker S. GORDON TAYLOR New York : Jacob Altner, Edward F. Goss, Robert Hough, John C. Kalm- bach, Jr., Harry E. Kentzel, Maynard J. Lonis, R. H. Tomlinson North Carolina: Marvin D. Dixon THE list of Official RADIO NEWS 1240 XEFB Monterrey, N. L. 100 Ohio : Donald W. Shields, Richard J. Broadcast Band Listening Post Ob- 1240 XEAI Mexico, D. F. 250 Southward - 1270 XFB Jalapa, Ver. 250 Pennsylvania : Joseph Stokes servers is constantly growing, but addi- 1310 XFA Aguascalientes, Ags. 5 Texas: E. L. Kimmons tional applications for appointment are 1310 XEZ Monterrey, N. L. 50 Wyoming: J. H. Woodhead 1310 XECW Mexico, D. F. 10 invited from all regular DX'ers who care 1310 XEFC Merida, Yucatan 100 Foreign to function in this capacity, and who, if 1310 XEFW Tampico, Tams. 250 Australia: Albert E. Faull, Victoria; are to submit monthly 1310 XETB Torreon, Coah. 125 F. Ingle, New Wales appointed, willing 1370 XEFE Nuevo Laredo, Tamps. 100 George South reports to this department covering their 1370 XEFZ Mexico, D. F. 50 Canada: William H. Ansell, Saskatche- wan ; C. R. Caraven, Vancouver ; C. DX achievements. Each Official Observer 1370 XEZZ San Luis Potosi, S. L. P. 100 1370 XEL Saltillo, Coah. 100 Holmes, British Columbia; Philip H. will receive a formal certificate like that 1370 XEI Morelia, Mich. 125 Robinson, Nova Scotia pictured on the opposite page. England: R. T. Coales, Hants ; F. R. Crowder, Yorkshire ; George Ellis, N. In the effort to make this DX Corner Stockport. best serve the interests of DX listeners, Cuban DX Programs Newfoundland: A. L. Hynes, Caren- the editor will be more than glad to have Following is a list of DX transmissions ville New Zealand : L. W. Mathie, Hawke's the comments and suggestions of readers. to be put on by Cuban stations over a Bay ; R. H. Shepherd, Christchurch; period of three months. Arrangements for Eric W. Watson, Christchurch. RADIO NEWS DX Broadcast these South Africa : A. C. Lyell, Johannes- broadcasts were made by the National burg Station WSVS, the Seneca Vocational High Radio Club of York, Pennsylvania, the of- Sweden : John S. Bohm, Malung of New York, will dedicate ficers of which deserve great credit for Switzerland : Dr. Max Hausdorff, Vi- School Buffalo, ganello their F. C. C. monitor period of March 6 working out such an excellent array of to RADIO NEWS. This broadcast will con- programs. Readers of RADIO NEWS are tinue twenty minutes, beginning at 3:30 urged, to show their appreciation by sending reports to such of these stations as a.m., E.S.T., on that date. We hope all 565 10 TGW Guatemala City, Guatemala readers hearing this broadcast will drop a they succeed in logging. All hours are 570 5 2YA Wellington, New Zealand line of acknowledgment to this station. a.m., Eastern Standard Time. 574 100 Stuttgart Germany 580 1 7ZL Hobart, Tasm., Australia Observer Kalmbach arranged for this Date Time Call Kc. Location) 590 10 JOAK -2 Tokyo, Japan broadcast. Feb. 5 2 -3 CMJP 1360 Moron 592 120 Vienna Austria 6 12 -4 CMHW 910 Cienfuegos 601 6.5 Rabat Morocco 9 1 -2 CMW 910 Havana 609 20 Florence Italy Stations in Mexico 10 2 -3 CMBS 775 Havana 610 10 JODK -1 Keijo, Korea, Japan Through the good offices of Felipe L. 13 1 -5 CMOX 1325 Havana 610 4.5 3AR Melbourne, Viet., Australia 16 2 -3 CMOK 1250 Havana 618.5 50 KZRM Manila, Philippine Islands. Saldana, the following list of Mexican sta- 20 12 -4 CMHW 910 Cienfuegos 620 .5 4ZP Invercargill, New Zealand tions is presented: 22 1 -2 CMCA 1230 Havana 625 5 JOTK Matsuye, Japan 25 2 -3 CMJP 1360 Moron 629 15 Lisbon Portugal Kc. Call Location Watts 27 12-4 CMHW 910 Cienfuegos 630 4.5 LS3 Buenos Aires, Argentina 560 XEAO Mexicali, B. C. 250 27 2 -3 CMBS 775 Havana 630 .1 CKOV Kelowna, B. C., Canada 590 XEPN Piedras Negras, Coali. 50000 Mar. 5 2 -3 CMJP 1360 Moron 635 .5 JODG Hamamatsu, Japan 610 XFX Mexico, D. F. 1000 6 12-4 CMHW 910 Cienfuegos 635 7.5 5CK Crystal Brook, Australia 630 XEZ Merida, Yucatan 500 9 1 -2 CMW 910 Havana 638 120 Prague Czechoslovakia 660 XEOX Saltillo, Coah. 1000 10 2 -3 CMBS 775 Havana 645 .5 JQAK Dairen, Japan 690 XET Monterrey, N. L. 500 13 1 -5 CMOX 1325 Havana 645 .3 JOUK Akita, Japan 710 XEN Mexico, D. F. 1000 13 12 -4 CMHW 910 Cienfuegos 648 15 Lyons France 720 XEFI Chihuahua, Chih. 250 20 12-4 CMHW 910 Cienfuegos 650 .5 1YA Auckland, New Zealand 750 XEMC Merida, Yuc. 250 24 2 -3 CMBS 775 Havana 655 .3 JOCG Asahogawa, Japan 760 XEBC Aguacaliente, B. C. 5000 25 2-3 CMJP 1360 Moron 658 100 Cologne Germany 780 XEYZ Mexico, D. F. 10000 27 12-4 CMHW 910 Cienfuegos 658 100 Langenburg Germany 810 XFC Aguascalientes, Ags. 350 29 2 -3 CMCA 1230 Havana 660 75 XGOA Nanking, China 820 XETW Mexico, D. F. Apr. 4 12 -4 CMHW 910 Cienfuegos 665 3.5 - 2FC Sydney, N. S. W., Australia (Off for some time) 500 5 2 -3 CMJP 1360 Moron 668 50 No. Regional Great Britain 850 XETZ Mexico, D. F. 500 6 1 -2 CMW 910 Havana 670 10 JFAK Taihoku, Formosa, Japan 860 XEMO Tijuana, B. C. 2500 7 2 -3 CMBS 775 Havana 675 YV6RV Valencia, Venezuela 890 XEW Mexico, D. F. 50000 11 12 -4 CMHW 910 Cienfuegos 677 25 Softens Switzerland 920 XEOK Tijuana, B. C. 2500 13 1 -5 CMOX 1325 Havana 680 .5 JOVK Hakodate, Japan 940 XEFO Mexico, D. F. 5000 18 12 -4 CMHW 910 Cienfuegos 681 1 HJN Bogota, Columbia 960 XEAW Reynosa, Tamps. 10000 21 2 -3 CMBS 775 Havana 690 3.5 6WF Perth, W. Austr., Australia 970 XEP Mixcoac, D. F. 500 25 2 -3 CMJP 1360 Moron 695 7 PTT Paris, France 970 XES Tampico, Tams. 250 28 12 -4 CMHW 910 Cienfuegos 700 .5 JOKE Okayama, Japan 980 XEU Veracruz, Ver. 100 704 55 Stockholm Sweden 980 XEAE Tijuana, B. C. 250 710 3 303K Kanazawa, Japan 1020 XEJ Cidad. Juarez, Chih. 250 Foreign Station Locations 713 50 1IRO Rome, Italy 1030 XEB Mexico, D. F. 10000 720 1 JFBK Tainan, Formosa, Japan 1040 XEFG Mexico, D. F. 250 This list provides the call, location, fre- 720 .5 JORK Kochi, Japan 1060 XEA Guadalajara, Jal. 125 quency and power of each foreign station 720 2.5 3YA Christchurch, New Zealand 730 2 5CL Adelaide, Australia 1080 XEAF Nogales, Son. 250 in U. S. Decem- 1100 XEK Mexico, D. F. 100 reported heard the during 735 1 JOSE Kokura, Japan 1120 XENT Nuevo Laredo, Tams. 150000 ber by Official L.P.O.'s. See the "Consoli- 740 100 Munich Germany 1150 XEWZ Mexico, D. F. 100 dated `Best Bets'" list elsewhere on these 750 10 JOBK -1 Osaka, Japan 1150 XEH Monterrey, N. L. 250 750 2.5 KGU Honolulu, Hawaii 1150 XEY Merida, Yucatan 10 pages for a record of foreign stations heard 760 2.5 4QG Brisbane, Qnsld, Australia 1160 XED Guadalajara, Jal. 500 in your part of the U. S. (or Canada). 767 25 Mid.RegionalGreat Britain 1210 XEFV Ciudad Juarez, Chih. 100 770 10 JOHK Sendai, Japan 1210 XEFJ Monterrey, N. L. 100 Kc. Kw. Call Location 780 .5 JOPK Shizuoka, Japan 1210 XEMZ Tijuana, B. C. 30 546 120 Budapest Hungary 780 .25 KFQD Anchorage, Alaska 1210 XETH Puebla, Pue. 100 556 100 Beromiinster Switzerland 785 120 Leipzig Germany 1210 XEE Durango, Dgo. 50 560 7.5 2CB Corowa, N.S.W., Australia 790 10 JOGK Kumamoto, Japan 1210 XEAB Nuevo Laredo, Tamps. 7 560 7.5 2C0 Corowa, N.S.W., Australia 790 8 LR10 Buenos Aires, Argentina 1240 XEAZ Leon, Gto. 7 564 60 Athlone Irish Free State 790 .5 4YA Dunedin, New Zealand

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 565

795 5 Barcelona Spain 800 5 3LO Melbourne, Viet., Australia 804 50 Scottish Reg. Great Britain 810 10 JOCK -1 Nagoya, Japan 814 50 Milan Italy OFFICIAL 315 .25 PRA6 Rio de Janeiro, Brazil 820 .065 2ZH Napier. New Zealand L. P. O. 830 16 LR5 Buenos Aires, Argentina 830 10 JOIK Sapporo, Japan CERTIFICATE 832 100 RW39 Moscow IV, U.S.S.R. 840 .2 2YC Wellington, New Zealand A reproduction of 840 .34 CMQ Havana, Cuba the certificate which 840 .4 VOGY St. Johns, Newfoundland is 841 100 Berlin Germany issued annually 845 2 ZBW Hong Kong, China to each Official RA- B. 850 1.5 Valencia Spain DIO NEWS Broadcast 850 10 JOFK Hiroshima, Japan 855 3 2BL Sydney, N.S.W., Australia Band Listening Post 859 15 Strasbourg France Observer. Framed \[)!O Nh`W'ti 870 2.1 LR6 Buenos Aires, Argentina and lazing over the 870 10 JOAK -1 Tokyo, Japan : Í":; )iì';-..a:\'::ì' 877 50 London Reg. Great Britain DX receiver this 880 .15 1YX Auckland, New Zealand should lend an in- fK9:pvAs` _z,.',.U J ìvzì:4; ACY=,,;Tâ 900 10 JODK -2 Keijo, Korea, Japan teresting touch to 900 .5 KGBU Ketchikan, Alaska 904 100 Hamburg Germany the listening post 910 6 LR2 Buenos Aires, Argentina 910 2 4RK Rockhampton, Australia 913 60 Toulouse France 920 .5 JOQK Niigata, Japan 920 1 1111K Port-au- Prince, Haiti 922 32 OKB Brno, Czechoslovakia 930 .4 3UZ Melbourne, Australia 930 .5 JOAG Nagasaki, Japan 940 .5 JONK Nangano, Japan ner, Brooklyn; R. H. Tomlinson, Port 830 LR5 O 1 9 - 830 JOIK - - - - - 941 10 Goteborg Sweden E. Kentzel, Rensselaer * 950 17 Breslau Germany Chester; Harry 832 RW39 950 12 LR3 Buenos Aires, Argentina County. Column 2 (Connecticut) -Fred 840 VOGY 841 Berlin 950 1 2GB Sydney, N.S.W., Australia Burleigh, Meriden; James A. Dunigan, New 959 100 ParisienFrance 850 JOFK Poste 3 960 10 XEAW Reynosa, Mexico Britain Column (Montana -Wyoming) 855 2BL - * 3 * 6 960 .3 5DN Adelaide, Australia -R. W. Schofield, Missoula, Montana; 870 LR6 * 11 960 .3 JOOK Kyoto, Japan J. H. Woodhead, Monarch, Wyoming. 870 JOAK -1 5 960 5 YV1RC Caracas, Venzuela 877 London Regional 4 Atkins, 111, ti 968 15 Grenoble France Column (Missouri) -Dudley 900 JODK -2 * 970 .5 JOBG Maehashi, Japan Kansas City; T. E. Gootee, Springfield. 900 KGBU Hamburg 1 * - 2 2 977 50 W. Regional Great Britain B. 904 - - - Column 5 (Michigan- Ohio) -Ralph 910 LR2 6 - - - 978 1 XGOD Hangchow, China * [980 .5 JOXK Tokushima, Japan Baldwin, Ann Arbor, Michigan; Howard 910 4RK 913 Toulouse 4 5 - 5 985 1 CE98 Santiago, Chile W. Eck, E. Lansing, Michigan; Richard - - - - 920 JOQK 2 986 10 Genoa Italy J. Southward, Toledo, Ohio. Column 6 990 .3 JOFG Fukui, Japan 920 HHK (Nova Scotia, Canada) -Phil Robinson, 922 OKB, Brno 990 12 LR4 Buenos Aires, Argentina * 7 930 JOAG 995 20 Hilversum Holland Shelburne. Column (Saskatchewan, Can- a: .05 4GR Toowoomba,Qnsld., Australia 940 JONK 1000 ada)- William H. Ansell, Regina. Column Breslau 1004 13.5 OKR Bratislava, Czechoslovakia 950 8 Dixon, 950 LR3 1010 .3 3HA Hamilton, Viet., Australia (North Carolina)- Marvin D. 950 2GB 1013 50 N. National Great Britain Shelby. 959 Poste Parisien * 2 - - 2 5 - 2 1025 1 2UE Sydney, N.S.W., Australia Listeners living in the general vicinity of 960 JOOK * 1030 5 LR9 Buenos Aires, Argentina 960 o _ 1040 2" 5PI Crystal Brook, Australia any of these observers, by following down YV1RC - 5 968 1040 10 CP4 La Paz, Bolivia the corresponding column, can determine Grenoble 970 JOBG * 1031 60 Konigsberg Germany the foreign stations actually being heard in 977 West 6 1050 50 Scottish Nat'lGreat Britain Regional 980 JOXK * 1059 20 Bari Italy his locality. If none of the observers is 986 Genoa * 1077 12 Bordeaux France near you, the column or columns repre- 990 JOFG 1085 10 JOBK -2 Osaka, Japan senting the section of the country closest 990 LR4 1104 1.5 Naples Italy aid in searching for foreign 995 Hilversum * 1120 1 CHSJ St. Johns, New Brunswick to you will you 1004 OKR Bratislava 1 1125 1 2UW Sydney, N.S.W., Australia stations. 1010 3HA 1131 10 Horby Sweden The locations and power of all stations 1013 North Regional 6 - 7 Turin Italy 1140 1025 2UE 1145 .75 4BC Brisbane, Qnsld., Australia will be found in the "Foreign Station Lo- 1030 Liés * 50 W. National Great Britain in these pages. 1149 cations" list 1040 CP4 10 _ x 5 LR8 Buenos Aires, Argentina - * - - 1150 1031 Konigsberg 1158 2.6 OKM Kosice, Czechoslovakia Kc. Call 1 2 3 4 5 6 7 8 1077 Bordeaux * 1175 10 JOCK -2 Nagoya, Japan 3 - 2 - - - 1085 JOBK -2 * 1176 10 Copenhagen Denmark 560 2C0 1104 Naples 2 1180 .4 3DB Melbourne, Australia 565 TGW * - s° 2 * - * * 1125 2UW 1190 .01 VE9EK Montmagny, Quebec, Canada 570 2YA * - 1131 Horby 1190 5 LS2 Buenos Aires, Argentina 574 Stuttgart 1 - - - 2 - - - 1140 Turin 2 O - - 2 1 - 1195 17 Frankfurt Germany 609 Florence * - - - - 1 - - * 1145 4BC 1 2CH Sydney, N.S.W., Australia 610 3AR 1210 1149 West Regional 6 10 Trieste Italy 618.5 KZRM 1222 * 1150 LR8 * 1230 2 LS8 Buenos Aires, Argentina 625 JOTK 635 JODG 1158 OKM Kosice 1230 . CPX La Paz, Bolivia - 635 5CK 3 3 * 1175 JOCK -2 1240 1 WKAQ San Juan, Puerto Rico - - - - 638 Prague 5 * 1176 Copenhagen 1 - - - 2 1 - 1245 2 2NC New Castle, N.S.W., Aust'l k 645 JQAK 1190 VE9EK 1258 3 San SebastianSpain k s: 1190 LS2 * 9 - _ 1267 2 Ntirnburg Germany 645 JOUK 648 Lyons 2 1195 Frankfurt 1 2 - - 2 1270 1 2SM Sydney, N.S.W., Australia 650 1YA 6 1222 Trieste 2 - 2 1 - 1270 1 HIX Santo Domingo, Dominican * Republic 655 JOCG 1230 LS8 WNEL San Juan, Puerto Rico 658 Cologne - 2 1230 CPX 1290 .5 1240 WKAQ 1320 .25 KGMB Honolulu, Hawaii 658 Langenburg 1 660 XGOA 5 1267 Nurnburg - - - - 2 - - - 1456 10 Radio------668 North Regional 1270 HIX - - - 7 Normandie Fécamp, France * _ 2 * 670 JFAK * 1290 WNEL - - 1474 1 Bournem'th Great Britain 675 YV6RV * 1320 KGMB 680 JOVK * 1456 Radio-Normandie 2 681 HJN Consolidated Foreign "Best 700 JOKK Bets" 710 JOJK Canadian Monitor Schedules 720 JORK Following is a list of the foreign stations 720 3YA Through the teamwork of Gordon S. 735 JOSK Brighton, Massachusetts; William reported heard by Official Observers in dif- 740 Munich 1 0 - - 2 Wallace, ferent sections of the U. S. and Canada. 750 JOBK -1 - - 5 T. Turvey, Fredericton, N. B., Canada; 750 KGU - - 1 4 Wherever either an asterisk ( *) or a num- and C. Stillwell, Fredericton, N. B., Can- 760 4QG * * 3 - Eastern ber appears in a column it indicates that 767 Midland Regional * ada, the following schedule for the station has been heard in the section 770 JOHK - - '2 - Canadian stations is presented. These trans- represented by that column. Where a 780 JOPK - - - - missions take place on the 19th and 20th 780 KFQD month during the early morning number appears it represents the approxi- 785 Leipzig 1 * - - of each mate local time when the station is heard. 790 JOGK hours indicated. 790 LR10 Heavy numbers represent p.m. and light 790 4YA E. S. T. Freq. Call Location Watts numbers a.m. 800 3L0 1:11-1:19 930 CHNS Halifax 1000 This list is made up from observers' re- 804 Scottish Regional 6 1:21-1:29 630 CFCY Charlottetown 1000 810 JOCK -1 1:31-1:39 1310 CJLS Yarmouth 100 ports as follows: Column 1 (New York) - 814 Milan 1:41-1:49 950 CRCS Chicoutimi 100 Robert Hough, New Rochelle; Jacob Alt- 815 PRA6 1:51-1:59 1120 CHSJ Saint John 100

www.americanradiohistory.com 566'- RADIO NEWS FOR MARCH, 1935

2:01 -2:09 550 CFNB Fredericton 500 3:30 1370 WQDM St. Albans, Vt. 100 First Wednesday of Each 2:11 -2:19 580 CHRC Quebec 100 1210 WKOK Sunbury, Pa. 100 Month 2:21 -2:29 930 CFCH North Bay 100 3:40 1310 WMBO Auburn, N. Y. 100 2:00 1310 WEBR Buffalo, N. Y. 100 2:31 -2:39 730 CFPL London 100 3:50 1370 WABY Albany, N. Y. 100 2:10 920 WPEN Philadelphia, Pa. 1250 2:41 -2:49 1310 CJKL Kirkland Lake 100 1210 WBAX Wilkes- Barre, Pa. 100 2:20 1310 WSAJ Grove City, Pa. 100 2:51 -2:59 580 CKCL Toronto 100 4:00 1220 WCAD Canton, N. Y. 500 2:30 1410 WHIS Bluefield, W. Va. 250 3:01 -3:09 1200 CKTB Port Dalhousie 100 1200 KOOS Marshfield, Ore. 100 2:40 1310 WFBG Altoona, Pa. 100 3:11 -3:19 1210 CHNC New Carlisle 100 4:10 1370 WRDO Augusta, Maine 100 2:50 1200 WPHR Petersburg, Va. 100 3:21 -3:29 1420 CKNC Toronto 100 1210 WBBL Richmond, Va. 100 3:00 1370 WDAS Philadelphia 3:31 -3:39 600 CFCO Chatham 100 900 KGBU Ketchikan, Alaska 500 1500 WKBB East Dubuque, Ill. 100 3:10 1410 Va. 250 4:20 1290 WNBZ Saranac Lake, N. Y. 1 50 WRBX Roanoke, 1310 WBRE Wilkes- Barre, Pa. j 100 1200 WHBC Canton, Ohio 100 Report from Great Britain 1200 KGVO Missoula, Mont. 100 1420 KGIW Trinidad, Colo. 100 R. T. Coales, Official L.P.O., reports the 4:30 1200 WNBO Silverhaven, Pa. 100 3:20 1210 WMBG Richmond, Va. 100 1500 KPQ Wenatchee, Wash. 100 1310 WTRC Elkhart, Ind. 50 following stations heard: 4:40 1310 WRAW Reading, Pa. 100 1370 KICA Clovis, N. Mex. 100 Kc. Call Location Kw. 1210 KGY Olympia, Wash. 100 3:30 1370 WSVS Buffalo, N. Y. 50 4:50 940 WAAT Jersey City, N. J. 500 1410 WBCM Bay City, Mich. 500 590 WEEI Boston, Mass. 1 1370 KRKO Everett, Wash. 150 1200 KGHI Little Rock, Ark. 100 620 Cairo, Egypt 20 5:00 570 WSYR -WSYU Syracuse, N. Y. f50 3:40 1310 WGH Newport News, Va. 100 650 WSM Nashville, Tenn. 50 1200 KFXD Nampa, Idaho 100 630 WGBF Evansville, Ind. 500 660 WEAF New York, N. Y. 50 5:10 1370 KVL Seattle, Wash. 100 1420 KIDW Lamar Colo. 100 680 KPO San Francisco, Calif 50 5:20 1310 KGEZ Kalispell, Mont. 100 3:50 1210 WOCL Jamestown, N. Y. 50 700 WLW Cincinnati, Ohio 500 5:30 1370 KUJ Walla Walla, Wash. 100 1410 WROK Rockford, Ill. 500 710 WOR Newark, N. J. 5 5:40 1310 KGCX Wolf Point, Mont. 100 1200 KBTM Paragould, Ark. 100 730 CKAC Montreal, Quebec 5 5:50 780 KGQD Anchorage, Alaska 250 4:00 880 WQAN Scranton, Pa. 250 740 WSB Atlanta, Georgia 50 6:00 890 KSEI Pocatello, Idaho 1310 WBOW Terre Haute, Ind. 100 760 WJZ New York, N. Y. 50 6:10 1200 KVOS Bellingham, Wash., 100 1280 KFBB Great Falls, Mont. 1000 790 WGY Schenectady, N. Y. 50 6:20 1310 KIT Yakima, Wash 100 4:10 1430 WHEC Rochester, N. Y. 500 820 WHAS Louisville, Ky. 50 6:30 1120 KRSC Seattle, Wash. 100 570 WOSU Columbus, Ohio 750 830 KOA Denver, Colo. 50 1370 KGFL Roswell, N. Mex. 100 860 WABC New York, N. Y. 50 4:20 1190 WSAZ Huntington, W. Va.. 1000 870 LR6 Buenos Aires, Arg., S. A. 2.1 1310 WBEO Marquette, Mich 100 890 XEW Mexico City, Mexico 50 1200 KADA Ada, Okla. 100 900 WJAX Jacksonville, Fla. 1 4:30 1500 WGAL Lancaster, Pa. 100 910 LR2 Buenos Aires, Arg., S. A. 6 570 WKBN Youngstown, Ohio 500 950 LR3 Buenos Aires, Arg., S. A. 12 1250 WCAL Northfield, Minn. 1000 980 KDKA Pittsburgh, Pa. 50 4:40 1070 WCAZ Carthage, Ill. 100 990 LR4 Buenos Aires, Arg., S. A. 12 1200 KFJB Marshalltown, Iowa 100 990 WBZ Springfield, Mass. 50 4:50 1400 WKBF Indianapolis, Ind. 500 1000 WHO Des Moines, Iowa 50 1420 WACO Waco, Texas 100 1020 KYW Philadelphia, Pa. 10 5:00 1070 WDZ Tuscola, Ill. 100 1040 WTIC Hartford, Conn. 50 1200 KGDE Fergus Falls, Minn. F100 1060 WBAL Baltimore, Md. 10 5:10 900 WLBL Stevens Point, Wisc. 2500 1070 WTAM Cleveland, Ohio 50 1250 WLB Minneapolis, Minn. 1000 1080 WBT Charlotte, N. C. 50 5:20 1400 WBAA West Lafayette, Ind. 1090 KMOX St. Louis, Mo. 50 1200 WIL St. Louis, Mo. 100 1100 WLWL New York, N. Y. 5 5:30 1440 WTAD Quincy, Ill. 500 1100 WPG Atlantic City, N. J. 5 1320 KGHF Pueblo, Colo 500 1110 WRVA Richmond, Va. 5 5:40 1240 WXYZ Detroit, Mich. 1000 1130 KSL Salt Lake City, Utah 50 1140 KV00 Tulsa, Okla. 25 1150 WHAM Rochester, N. Y. 50 First Thursday of Each Month 1170 WCAU Philadelphia, Pa. 50 2:00 1210 WSOC Charlotte, N. Car. 100 1190 WOAI San Antonio, Texas 50 2:10 1420 WSPA Spartansburg, S. Car. 100 1190 LS2 Buenos Aires, Arg., S. A. 5 2:30 1310 WSGN Birmingham, Ala. 100 1230 WNAC Boston, Mass. 1 2:40 1420 WJBO (CPonly) Baton Rouge, La. 100 1230 LS8 Buenos Aires, Arg., S. A. 2 2:50 1210 WGCM Miss. City, Miss. 100 1260 WTOC Savannah, Ga. 1 3:00 1500 WRDW Augusta, Ga. 100 1300 WBBR Brooklyn, N. Y. 1 1200 WHBY Green Bay, Wise. 100 1330 WDRC Hartford, Conn. 1 1310 WDAH El Paso, Texas 100 1410 WAAB Boston, Mass. .5 3:10 1240 WKAQ San Juan, P. R. 1000 1470 WLAC Nashville, Tenn. 5 1420 WJMS Ironwood, Mich. 100 1480 WKBW Buffalo, N. Y. 5 1370 KLUF Galveston, Texas 100 1490 WCKY Covington, Ky. 5 3:20 1360 WCSC Charleston, S. Car. 500 1210 WEDC Chicago, Ill. 100 Courtesy- Observer Tomlinson 1310 KTSM El Paso, Texas 100 Report from Switzerland 3:30 1440 WBIG Greensboro, N. Car. 500 THE BERLIN TRANSMITTER 1370 KGKL San Angelo, Texas 100 Official L.P.O. Hausdorff reports the f ol- (841 KC., 100 KW.) 3:40 1340 WCOA Pensacola, Fla. 500 lowing DX stations well heard at his lis- 1210 WSBC Chicago, Ill. 100 tening post in the Swiss mountains: Here are shown the transmitter house 1310 KFPM Greenville, Texas 15 and antenna of the new German sta- 3:50 1360 WQBC Vicksburg, Miss. 500 Kc. Call Location Kw. 1420 KFIZ Fond du Lac, Wise. 100 tion, located at Tegel, a suburb of 1370 KMAC San Antonio, Texas 100 175 Moscow, U.S.S.R. 500 Berlin 4:00 580 WDBO Orlando, Fla. 250 Aires, Arg., S. A. 16 830 Lßá. Buenos 1210 WEBQ Harrisburg, Ill. 100 York, N. Y. 50 860 WABC New 1310 KFYO Lubbock, Texas 100 Buenos Aires, Arg , S. A. 870 LR6 2.1 4:10 1430 WNBR Memphis, Tenn. 500 10 6:40 1310 KXRO Aberdeen, Wash. 100 1060 WBAL Baltimore, Md. 1200 WMPC Lapeer, Mich. 100 50 6:50 1120 KFIO Spokane, Wash. 100 1170 WCAU Philadelphia, Pa. 1370 KONO San Antonio, Texas 100 220 WCAD Canton, N. Y. .5 7:00 1210 KFJI Klamath Falls, Ore. 100 7:10 1310 KMED Medford, Ore. 100 4:20 560 WQAM Miami, Fla. 1000 7:20 1420 KORE Eugene, Ore. 100 1210 WHBF Rock Island, Ill. 100 F. C. C. Monitor Schedule 4:30 1220 WDAE Tampa, Fla. 1000 1500 WKBZ Ludington, Mich. 100 The following is the monitor schedule of First Tuesday of Each Month 1370 KFJM Grand Forks, N. Dak. 100 the Federal Communications Commission, 2:00 1210 WQDX Thomasville, Ga. 100 4:40 1210 WCBS Springfield, Ill. 100 2:10 1200 WBHS Huntsville, Ala. 100 4:50 880 WCOC Meridian, Miss. 500 corrected to December 19, 1934. These sta- 2:20 1370 WHBQ Memphis, Tenn. 100 1500 WKBV Richmond, Ind. 100 tions are on the air twenty minutes each, 2:30 1420 WEED Rocky Mount, N. Car. 100 5:00 1300 WIOD Miami, Fla. 1000 beginning with the time shown. During 2:40 1500 WOPI Bristol, Tenn. 100 1210 WTAX Springfield, Bl. 100 2:50 1320 WSMB New Orleans, La. 500 1310 KGBX Springfield, Mo. 100 these transmissions these stations operate 3:00 1370 WMBR Tampa, Fla. 100 5:10 1260 WTOC Savannah, Ga. 1000 on cleared channels and each station an- 3:10 1420 WNRA Muscle Shoals, Ala. 100 1370 WHBD Mt. Orab, Ohio 100 nounces its call letters at three -minute in- 3:20 1310 WSJS Winston- Salem, N. Car. 100 1420 KCMC Texarkana, Ark. 100 3:30 1500 WHEF Kosciusko, Miss. 100 5:20 1210 WHBU Anderson, Ind. 100 tervals. This list enables DX'ers to log 3:40 1200 KMLB Monroe, La. 100 5:30 1370 WIBM Jackson, Mich. 100 these low -power stations, most of which 3:50 1370 WAGF Dothan, Ala. 100 . 1420 KGFF Shawnee, Okla. 100 normally be heard at a distance be- 4:00 1290 WNEL San Juan, P. R. 500 5:40 1210 WOMT Manitowoc, Wisc. 100 cannot 1200 KWG Stockton, Calif. 100 1500 KNOW Austin, Texas 100 cause of numerous other stations operating 4:10 1310 WTJS Jackson, Tenn. 100 on the same frequencies. 1500 KPJM Prescott, Ariz. 100 First Friday of Each Month 4:20 1370 WPFB Hattiesburg, Miss. 100 1370 KERN Bakersfield, Calif. 100 3:00 1210 WJW Akron, Ohio 100 First Monday of Each Month 4:30 1420 WGPC Albany, Ga. 100 1310 KRMD Shreveport, La. 100 E.S.T.Freq. Call Location Watts 1500 KXO El Centro, Calif. 100 3:10 1420 WPAD Paducah, Ky. 100 a.m. 4:40 1200 WBNO New Orleans, La. 100 1500 KOTN Pine Bluff, Ark. 100 2:00 1500 WCNW Brooklyn 100 1210 KIEM Eureka, Calif. 100 3:20 1210 WCOL Columbus, Ohio 100 1310 WJAC Johnstown, Pa. 100 4:50 1310 KROL Knoxville, Tenn. 100 1310 KFXR Oklahoma City, Okla. 100 2:10 1210 WFAS White Plains 100 1440 KLS Oakland, Calif. 250 3:30 1420 WELL Battle Creek, Mich. 50 1370 WRAK Williamsport, Pa. 100 5:00 1500 WDNC Durham, N. Car. 100 1200 KGEK Yuma, Colo. 100 1210 Zanesville, 2:20 1500 WNBFJ Binghamton, N. Y. 100 1420 KGIX { Las Vegas, Nev. 100 3:40 WALR Ohio 100 580 WCHS Charleston, W. Va. 500 5:10 1200 WJBW New Orleans, La. 100 1310 KFPL Dublin, Texas 100 2:30 1420 WAGM Presque Isle, Maine 100 1320 KGMB Honolulu, Hawaii 250 3:50 1420 WMBC Detroit, Mich. 100 1370 WBTM Danville, Va. 100 5:20 1310 WAML Laurel, Miss. 100 1200 WCAT Rapid City, S. Dak. 100 2:40 1200 WLVA Lynchburg, Va. 100 1370 KRE Berkeley, Calif. 100 4:00 1310 WFDF Flint, Mich. 100 2:50 1420 WHDL Tupper Lake, N. Y. 100 5:30 1210 WSIX Springfield, Tenn. 100 1240 KGCU Mandan, N. Dak. 250 1310 WHAT Philadelphia, Pa. 100 750 KGU Honolulu, Hawaii 2500 4:10 1200 WFBE Cincinnati, Ohio 100 3:00 1200 WCAX Burlington, Vt. 100 5:40 1370 KGAR Tucson, Ariz. 100 1370 KWYO Sheridan, Wyo. 100 3:10 1500 WSYB Rutland, Vt. loo 5:50 1310 KCRJ Jerome, Ariz. loo 4:20 1450 WGAR Cleveland, Ohio 500 1310 WTEL Philadelphia, Pa 100 6:00 1100 KGDM Stockton, Calif. 250 1240 KLPM Minot, N. Dak. 250 3:20 1200 WIBX Utica, N. Y. 100 6:10 1200 KSUN Lowell, Ariz. 100 4:30 1200 WCLO Janesville, Wisc. 100 1280 WCAM Camden, N. J. 500 6:20 740 KTRB Modesto, Calif. 250 (Continued on page 586)

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 567

was hard to judge by ear alone. Due to that the user may have to remove a turn the absence of heterodyne squeals of 10 kc., or two from the tickler windings, particu- we must conclude that the audio amplifier larly if the detector is a tetrode or a pen- or speaker does not reproduce this fre- tode. quency. On the other hand, the crispness When we approach the subject of selec- of speech and the natural reproduction of tivity we have to do a little rationalizing. certain instruments gave evidence of fre- Regenerative receivers have an artificial quencies higher than 5000. sort of selectivity when they are on the One of the noteworthy results was that brink of oscillation, but we might say that some small stations which never sound ac- their "rejectivity" is poor. With the cir- ceptable on ordinary receivers sounded cuit tuned to one frequency, a strong sta- much better on this outfit, although the tion on a nearby frequency may readily difference in quality from different stations ride through. If the feed -back action is is marked. stepped down even a little, the artificial Since this set was made and designed selectivity disappears and the set is ex- without the help of engineering measure- tremely broad, as any set with only a ments or the benefits of response curves, single tuned stage will be. these results seem to be all one could The only way to increase the real selec- hope for. tivity is to add more tuned stages. This sounds easy, but with an existing small straight regenerative receiver the necessity for thorough shielding makes the under- Improving Your taking impracticable from the start. In the long run it is easier and cheaper to Receiver build or buy a whole new receiver than to attempt the addition of a tuned r.f. stage (Continued from page 549) to a straight regenerator. While many small regenerative receivers from the pesky antenna and eliminates compare favorably with superheterodynes dead spots on all coil ranges. No addi- in the matter of usable sensitivity, their -Fidelity Reception tional controls of any kind are required, comparatively poor selectivity is the price High and the extra tube can be accommodated you pay for their simplicity, economy and (Continued from page 537) without trouble on most chassis. reliability. Recently the writer made a The circuit of Figure 1 is changed as the feet over well. side -by -side test between a five -tube t.r.f.- operated with -came indicated in Figure 3 if dry -cell operation The extent of the high- frequency response regenerative receiver and an eight -tube su- is to be retained. The new tube, V3, is a perheterodyne, both of well -known make. type 34 pentode, with its filament merely While the former brought in everything the bridged across to the existing filament cir- latter did, frequently with less noise, the cuit for control by the same rheostat. super cleanly separated bunched stations Now the ideal method of coupling the that sounded like so much hash in the other plate of V3 to the input of Vl is by means set. If you own a regenerative receiver, of a primary co;' next to but not connected you simply must recognize these facts. conductively to the grid winding of Ll. Since it is altogether impracticable to arrange such a primary on a four -prong coil, and since there is no sense in buying a new set of three- winding, six -prong coils, Set Building we can use direct coupling with the aid of a simple blocking condenser, C5. This (Continued from page 535) should be a good mica condenser of ábout .01 mfd. Also, the grid leak R2 is shifted incorporating these latest principles. Our across the grid filament, where it works technical staff maintains steady contact just as well as across the grid condenser. with America's foremost designers in the The d.c. plate supply for V3 now flows "How to Build" field. through the grid coil of Ll, without affect- This month we are giving to our read- THE UNIQUE BAFFLE ing the latter's radio -frequency operation ers a number of designs in different fields, This construction provides ample baffle in the slightest. It cannot bias the detector some simple and some more complicated. area for reproduction of the "lows ", grid because the grid condenser C4 is in The Editors feel that these designs are the yet is reasonably compact. It will be the way, and it cannot short itself back to finest that have been put before the set - noted that parallel surfaces and right filament because C5 is in the way. The building public for some time and that angles are studiously avoided, thus reactance of C5 to signal currents is so low they offer the set -builder the chance he obtaining freedom from cabinet reso- that it practically doesn't exist, while its has been waiting for to build a receiver nance capacity is so large in relation to the tuning really worth while and one that will pro - condenser Cl that it has no appreciable duce results in both distance reception and detuning effect even though it is in series in high quality of reproduction. with Ll and Cl. Other articles in this issue also give im- R3 in Figures 3 and 4 is indicated as a portant information to the set -builder in fixed resistor. This is not critical in value; helping him to design his own circuits. anything between 10,000 and 25,000 ohms Many of the set -builders who are our read- being acceptable. A 2.5 -, 5- or 8-millihenry ers prefer to lay out their own sets, relying r.f. choke may also be used in this posi- on RADIO NEWS articles for a description tion. It is well to try both resistors and of new principles that they can incorporate chokes here. into their experimental designs. So our With an a.c. receiver, the changes are advice to the set -building fraternity is, to shown as in Figure 4. The new tube, V3, read every article in this and the coming is now a 58 (or 6D6) and is provided with two numbers, as there will be found a a 300 -ohm cathode resistor for grid bias wealth of experimental material, any one and a 75,000 -ohm screen resistor so that item of which might contain just the nec- screen voltage can be taken off the 250 - essary information they have been looking volt plate lead. for to complete their new sets. Of course, An untuned r.f. stage of the kind de- the sets that we are describing are complete scribed furnishes appreciable amplification, in all details and the reader should follow but its slight cost would be worth while each article in the series. anyhow for its stabilizing effect on the RADIO NEws' policy of putting out blue- regenerative detector. Furthermore, it pre- prints of its main designs will also be found vents the latter, when oscillating, from to be a help to set constructors, and as the shocking the antenna into oscillation and list of available blueprints grows, the radiating energy on its own accord. Def- Editors promise that efficient receivers for inite logging of stations becomes easier with any kind of use and fitting any pocketbook the antenna thus removed from the tuned will be adequately covered. Follow RADIO circuit. Feed -back is more certain than NEWS designs in your experimental set - go far before ; in fact, it may be so much better building, and you cannot wrong!

www.americanradiohistory.com 568 RADIO NEWS FOR MARCH, -1935 HOW TO BUILD, TEST AND REPAIR RADIO SETS

Radio Construction Library Including Television, Short -Wave Receivers and Auto THE TECHNICAL 3 51/4x8 REVIEW Radios, Volumes, -1177 pages, 561 Illustrations. This practical Library includes: PRACTICAL RADIO JOSEPH CALCATERRA -The fundamental principles of radio, presented in an understandable manner. Illustrated with working diagrams. PRACTICAL RADIO CONSTRUCTION AND REPAIR -Methods of locating trouble and reception Perpetual Trouble Shooter's faults and making workmanlike repairs. Discusses mod- Manual, Readers who are interested in any one ern Short -Wave Receivers and installation of automobile . Volume V, by John F. Rider, published by of the above subjects will find radios fully. RADIO RECEIVING TUBES -Principles John F. Rider. some valu- underlying the operation of all vacuum tubes and their This new manual is a con- able information in the book. The section use in reception, remote control and precision measure- tinuation of the earlier manuals, ments. Volumes on propagation of waves discusses observa- Helps you to understand modern type receiving sets - I, II, III, and IV, and begins where Volume tions of the height of the ionosphere, full of construction data and practical kinks for the IV left the experimenter. off. It contains diagrams and ser- angle of incidence of the arriving vice information waves, Io Days Free Examination on numerous receivers, their apparent direction, polarisation, the Easy Terms most of which were released during the study of echoes, etc. The section on past year. There direc- is no duplication of dia- tional wireless shows several improved di- grams in Volume V and any of the previ- rection finders which use the cathode -ray FREE EXAMINATION COUPON ous volumes. tube as the indicator. For those who might not yet be familiar McGraw -Hill Book Company, Inc. with Mr. Rider's Manuals let us explain "Who's Who" in Amateur Radio, Edition 330 West 42nd Street, New York that they now contain some 5150 pages of B, Radio Amateurs Publishers, Send me the new RADIO CONSTRUCTION 1935. The LIBRARY, three volumes for 10 days' free examin- diagrams and information on commercially sub -title of the book approximately de- ation. If satisfactory I will send $1.50 in ten made receiving sets. The diagrams now scribes its purpose: "The days, and $2.00 a month until $7.50 has been paid. Radio Amateur's If not wanted I will return the books postpaid. practically all contain resistor and con- Directory of Operators, Stations, and Name denser values and the other information Schedules." This is mostly a collection of Home Address may consist of socket- layout chart, picture - short descriptions of amateur stations and City and State wiring diagram, voltage readings (at sock- their owners. Sometimes it includes pic- Position ets) and instructions for aligning. Any or tures of the owners and a part of their Name of Company RN-3-35 all of these may be shown depending on biography. Of course it does not contain whether the material was available to the information on all amateurs as yet, but author. The trend seems to be towards there seem to be more than in the previous more information per receiver. There are editions. Besides the "Who's Who" pages, n! models described in Volume V which oc- there is some information, useful to ama- 5 ERVICEmp cupy several pages of aligning and adjust- teurs: the Q- signals,'a list of abbreviations, ing instructions. For instance, the new schedules of weather and press stations and Atwater-Kent "Tune- O- Matic" receiver, a few short articles by well -known ama- which can tune itself and changes its tuning teurs. after each program by means of a clock - yourself to and-switch arrangement, can be found in The Wireless World Diary and experi- this volume. The reader can find the prin- menter's Handbook 1935, published by GREATER ciple of operation as well as the necessary Iliffe and Sons, Ltd. A- pocket diary which adjustments and how to make them. There at the same time contains useful data for are several more new and famous receivers the radio experimenter. The table of con- PROFITS included in Volume V. For instance: the tents this year is quite imposing. There Magic- Brain; a Howard nineteen tube set; are: Receiving License Regulations, a list There's no doubt about it. I can help ANY the Midwest 16; the Hammerlund Pro of European Broadcast stations and prin- serviceman who is willing to invest a little with a.v.c., etc. cipal s.w. stations, electrical interference, time and study with the aim of winning better symbols in common use; jobs and greater profits. And I can do it at a A new index has been prepared which thin comes the low price which will amaze you. comes with the volume. It contains all diary. This is followed by more technical data, useful Sprayberry's Practical Mechanics of Radio the receivers shown in all five volumes ar- formulae, 12 pages of align- Service will help you in a hundred ways - ranged by the name of the manufacturer ment chart for quickly solving these equa- just as it has helped countless others, many of and shows the volume and page number tions, wire tables, diagrams, some practical whom found ordinary courses too costly, too hints and elementary or impractical for their needs. where information on a given model can a list of tubes with their char- Certainly you owe it to yourself to investigate be found. acteristics. (These are European tubes.) -immediately! The diary itself even contains notes and Report of the Radio Research Board for hints on radio. NEWS FLASH I Several new lessons the period of January 1st, 1932 to Septem- on the use of the CATHODE-RAY TUBE ber 30th, 1933. Published by His Majesty's A Thermionic -Tube Measuring Instru- or OSCILLOGRAPH have just been added Stationery Office, 1934. This book can be ment, by Tom B. Wagner; Electrical En- fo the Sprayberry course -at no increase purchased from the British Library of In- gineering, December 1934. This paper in cost. Don't miss them! formation, 270 Madison Avenue, New describes a new type of tube meter em- York.. The cathode -ray tube figures prom- ploying a Wunderlich tube. It can be used inently in the work of the Radio Re- 2548 F. University N.W. L. SPRAYBERRY C. search Board. This report records the findings of the Board Without obligation on my part, please send during the period details of your system. Also tell me how I can mentioned and discusses the methods used Dots and Dashes get the new Sprayberry DATA SHEETS and the instruments employed. (worth $3) at no additional cost. The book (Continued from page 532) contains 137 pages and is devoted to re- Name searches on the propagation of waves, di- ings with an operator at the Radio Marine Full Address rectional wireless, atmospherics, electron Corporation station on Cape Cod. Both oscillation giving rise to centimeter waves, operators stated that the reception RN-3-35 was ex- radio- frequency standards, electrical mea- cellent. The previous record was a conver- surements at radio frequencies, interference sation from the same Cape Cod station to SPRAYBERRY'S PRACTICAL and receiver selectivity, a new wireless a plane carrying the Lindberghs while fly- transmitting station, time bases for use ing MECHANICS RA IO SERVICE over the southern Pacific at a distance with the cathode -ray oscillograph. of 5,000 miles.

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 569 as an ammeter, a voltmeter, a wattmeter or a power- factor meter and is claimed to be accurate to 2 per cent for frequencies from 100 to 3000 cycles. For higher frequencies, proper shielding and other refinements are necessary. Review of Articles in the De- cember, 1934 Issue of the Pro- ceedings of the Institute of Radio Engineers Generation and Utilization of Ultra - Short Waves in Radio Communication, by Frederick A. Kolster. Deals with the generation and utilization of ultra -short waves, below ten meters. Describes a novel circuit used to obtain a high degree of frequency stabilization, without resorting to frequency doubling or crystal control. ALL-WAVE A Lapel Microphone of the Velocity Type, by Harry F. Olson and Richard W. Carlisle. Discusses the requirements which must be met by lapel microphones and de- SUPERHETERODYNE designed to ac- scribes a new type of unit F. complish the required results. For World- Wide Reception Control of Radiating Properties of An- tennas, by C. A. Nickle, R. B. Dome, and W. W. Brown. Describes a system of tun- 10 -550 Meters, or 540 K.C. to 30 M.C. ing by which the current distribution and therefore the radiating properties of an antenna, may be varied over an extremely wide range. Easy to Build- Splendid Performance An Electron Oscillator with Plane Elec- trodes, by B. J. Thompson and P. D. Sponsored by Describes a new type of thermi- Zottu. BELDEN MFG. COMPANY HAMMARLUND MFG. COMPANY onic tube, capable of producing ultra -high 4647 W. Van Buren St., Chicago, III. 424 W. 33rd St., New York, N. Y. frequencies by means of electron oscilla- CORNELL- DUBILIER CORP. OAK MFG. COMPANY tions, using plane electrodes. 4377 Bronx Blvd., New York, N. Y. 711 W. Lake St., Chicago, III. Theory of the Electron Gun, by I. G. CROWE NAME PLATE MFG. COMPANY OHMITE MFG.!COMPANY Maloff and D. W. Epstein. Describes the 1749 Grace St., Chicago, Ill. 636 N. Albany Ave., Chicago, III. theory governing the use of the electron ELECTRAD, INC. OXFORD RADIO CORP. gun or cathode -ray tube to generate, con- 175 Varick St., New York, N. Y. 350 W. Huron St., Chicago, III. centrate, control and focus an electron ERIE CAN COMPANY MEISSNER MFG. COMPANY beam to a spot of a desired size. Design 816 W. Erie St., Chicago, III. 2815 West 19th St., Chicago, III. data on the construction of such guns is THORDARSON ELECTRIC MFG. CO. given. 500 W. Huron St., Chicago, III. Review of Contemporary AMAZING PERFORMANCE! SENSATIONAL DESIGN! Literature Distant stations in foreign lands come in Equal to the finest professional type communication on the ALL -STAR JUNIOR with splendid receivers, yet you can build it yourself without special The Voice -Operated Compandor, by N. volume and clarity. The regular American tools or test equipment. A soldering iron, screw- driver, Bell Laboratories Record, De- broadcasts are available when you desire and pliers are all you need to build the ALL -STAR C. Norman, conventional entertainment. Thrill your JUNIOR. cember, 1934. Description of the prin- family and friends with this receiver. system CONTINUOUS BAND SPREAD -over the entire tun- ciples of operation of a new control ing range makes possible the separation of hun- designed to automatically compress the dreds of stations that are jammed together at a intensity range of speech before transmit- single spot on the ordinary receiver dial. ting it and to expand it to its original in- BEAT -NOTE OSCILLATOR -using the new 6177 tube, range after it has traversed the brings in DX carrier waves inaudible on any other tensity short wave receiver. transmission medium. SUPERHETERODYNE CIRCUIT-Five tubes in the lat- Spot Welding, by Lawrence Ferguson. est design; does the work of 7 tubes! Bell Laboratories Record, December, 1934. PRE -ADJUSTED I. F. COILS -Tuned at the factory A chart showing approximately 250 differ- to 370 k.c. No adjustment required. ent combinations of metals which can be ALL ELECTRIC -For 110 -120 volts, 60 cycle, stand- spot welded with varying degrees of suc- ard A.C. house current. cess is given, together with information results in spot weld- STANDARD PARTS -Ask your radio dealer or jobber on how to obtain best for the ALL -STAR JUNIOR Foundation Unit that ing different metals. includes drilled sub and front panels, enlarged drawings of wiring and pictorial diagrams, three - An Improved Volume Indicator, by R. step assembly, and all instructions. Start with the E. Kuebler. Bell Laboratories Record, De- Foundation Unit. Buy the remaining parts as 1934. The circuit and design of you need them. For further information, fill out cember, coupon below. the new 700A volume indicator developed by the research department of the Bell Laboratories are given. The Operation of Several Transmitters on the Same Wavelength. The Wireless Engineer and Experimental Wireless, De- cember, 1934. An explanation of the va- hITAR rious factors which must be taken into -fir consideration when several transmitters are ALL-WAVE Superheterodyne * to be operated simultaneously on the same ALL -STAR HEADQUARTERS wavelength. 360 N. Michigan Ave., Chicago, III. "Radio Service" -Its Causes, Cures and Suggestions for Reduction in Service Costs, Free circuit diagram, parts list, and all information on the ALL -STAR JUNIOR. by R. C. Lawes. The Proceedings of the Institute of Wireless Technology, January - NAME March, 1935. An of approximately analysis ADDRESS 100 service cases with a chart showing (Continued on page 580) CITY STATE

www.americanradiohistory.com 570 RADIO NEWS FOR MARCH, 1935

PEG LA CENTRA

GERALDINE FARRAR LEFT: DOROTHY MORTON DOWNEY PAGE

BACKSTAGE in Chatty Bits on Radio BROADCASTING Personalities

ORTON DOWNEY, the noted radio Samuel Kaufman a bee -hive, through the "sound micro- J tenor who had been absent from the scope," was made to sound like the roar of air for a period while filling personal officials chose this word) of the Satur- Niagara Falls. A fishworm and a goldfish appearance engagements, has returned to day afternoon full -length opera programs were matched against each other to de- NBC Sunday afternoons and Tuesday direct from the Metropolitan Opera House termine which makes the most noise. Sub- nights in a new series sponsored by Carls- stage. Listerine is being ballyhooed this sequent broadcast tests revealed that many bad Sprudel Salts. NBC executives tell us year on the elaborate operatic presenta- "ghostly" noises are merely due to changes that Downey draws $6,000 per week on tions. Milton J. Cross continues to pre- of temperature or moisture in the ma- this program and thus ranks with the high- sent the action description. Miss Farrar terials of buildings. The sounds of cities est paid stars in broadcasting. Downey is presents human interest stories and anec- and voices were following subjects of radio accompanied on his semi -weekly programs dotes concerning the personalities con- programs based on the findings of the by Ray Sinatra's orchestra. nected with the day's performance. She "sound microscope." also interprets important passages, illus- THE cry for original musical comedy on trating them with piano and voice. KATE SMITH, who had been going the networks is still being heeded by along sponsorless for some time, now the program moguls. The Gibson Family IRENE BEASLEY, known to many radio once again heads the cast of a commercial (NBC), "Hollywood Hotel" (CBS), and fans as "the long, tall gal from Dixie," series. Sponsored by the Hudson Motor numerous other chain features with a dra- and Dorothy Page, one of the prettiest Car Company, Kate Smith's New -Star Re- matico- musical theme have been gaining girls in radio, have been designated as al- vue is heard Mondays over CBS. As the sufficient listener attention to warrant more ternate vocal soloists on Jesse Crawford's name of the program indicates, the broad- features of the type. "Gigantic Pictures, NBC pipe organ programs: Miss Beasley casts will embody a search for new talent Inc.," is a new NBC musical comedy fea- is presented on Crawford's Monday and -an idea that many programs seem to be ture presented by Tastyeast Sunday after- Friday programs while Miss Page is heard using these days. Kate plans to travel to The noons. program features Sam Hearn, with the organist's Sunday and Thursday a different municipality each Friday as comedian, and music by Johnny Blue's renditions. presiding judge in the final selection of the orchestra. Alice Frost, character actress, two "most talented" auditionists and the has also been cast in this series. While on DR. E. E. FREE, prominent sound ex- chosen ones will make their network debuts the subject of musical comedy, we might pert, recently, presented a novel scien- on her following Monday broadcast. Jack mention that Owen Davis, veteran play- tific series over CBS which attracted wide Miller's Orchestra and the Three Ambassa- wright, is now librettist for "The Gibson attention. The network's microphones dors, male trio, will be heard on the entire Family" feature. were brought right into the E. E. Free series. Laboratories, in New York, where a GERALDINE FARRAR, Metropolitan "sound microscope" was utilized to bring A NEW CBS Friday Opera Company star of more than a some very strange types series, "The of din to air lis- O'Flynn," is based on the decade ago, has returned to the scene of teners. A weevil running novel and around inside a the Broadway musical drama of her great triumphs as raconteuse (NBC grain of wheat was heard on the same the air with name. The program, sponsored by Esso, a bang and clatter. The humming inside differs from ALICE FROST the majority of current dra- KATE SMITH DR. C. C. CLARK AND DR. E. E. FREE

www.americanradiohistory.com RAmo NEWS FOR MARCH, 1935 571 STILL AHEAD in Performance!

AUTOMATIC VOLUME CONTROL

!-`YJ _ CRYSTAL FILTER

CO M ET 13 RO/' 11,012W STANDARD 1/' STANDARD + A.V.C. CRYSTAL CRYSTAL + A.V.C. EaECiEevER Operating on MILTON WATSON Battery, D.C., TWO YEARS ago, the Hammarlund COMET All models include the or A.C. in all matico -musical series in that its action is "PRO" Superheterodyne assumed instant distinctive features of single - Voltages and Cycles of the seventeenth century instead of the leadership because it met the exacting demands control band -spread tuning of professional operators and advanced amateurs, at all frequencies, without present. Viola Philo, a soprano- with con- interested in both phone and code reception be- extra coils -plus all other siderable radio experience, and Milton tween 15 and 250 meters. It still holds its eminence refinements one would expect in so advanced a sing the leading rôles. by virtue of conspicuous performance. r eceiver. Watson, baritone, and amateur 'phone Nathaniel Shilkret conducts a thirty -piece The Hammarlund files bulge with praise from The crystal model, for CW "PRO" users- amateurs, professionals, work, employs an improved crystal circuit (patent orchestra while David Ross is the an- air and steamship lines, broadcasting applied for). nouncer. The large dramatic cast is headed networks, police and armies and navies M R -in every corner of the world, who by Ray Collins, Lucille Wall, Jack Smart ex- HAMMARLUND MANUFACTURING CO., chose this amazing receiver after 424 -438 W. 33rd Street, New York, N. Y. and Leigh Lovell. The series had a pre- haustive competitive tests. tentious start and seemed headed toward Check here for FREE information on the Comet "Pro" Receiver. ID Cheek here for FREE new 1935 the hit classification. General Catalog. D Check here and attach 10c for 16 -page Hammarlund 1935 Short -Wave Manual, illus- radio dance trating and describing most popular S -W circuits of HARRY RESER, veteran Sot. tal7arr. T3ndia past year, with schematic and picture diagrams and orchestra conductor, has returned to parts list. the air on a new series sponsored by Wrig- jammarlundACC {SION Name ley's Spearmint Toothpaste. The program PRODUCTS Address heard on NBC Sunday afternoons also fea- RN-3 tures Peg La Centra, contralto, and Ray Hcatherton, baritone. Reser gained radio fame as conductor and banjoist of the old Clicquot Club Eskimos feature. Miss La PORTABLE SOUND SYSTEMS AMERTRAN announced over a Boston sta- Centra once UNITS tion and has appeared in both singing and ELECTRO DYNAMIC TRANSFORMERS dramatic rôles on NBC. Heatherton, who was once a boy soloist with the noted CARBON MICROPHONES For Quality Amplification Paulist Choristers, has had considerable NBC experience. AMPLIFIERS THE RCA Radiotron Company, spon- 4, 5 & 6 FT. ALL ALUMINUM sors of the Radio City Party programs TRUMPETS presented Saturday nights over NBC, have put an interesting twist into the broadcasts. FIELD EXCITERS Instead of dedicating the programs to outstanding established radio stars, as at the AIR COLUMN HORNS start of the series, the periods are being (Continued on page 576) LOW AND HIGH FREQUENCY UNITS FOR WIDE RANGE HARRY RESER THEATRE USE ACCEPT OUR SEND FOR NEW 32 PAGE CATALOGUE 5 Day This bulletin contains the most complete listing avail- FREE able of transformers and reactors for audio amplifica- TRIAL tion and transmission. It fully describes and illus- You can try any trates five complete lines, Toledo P.A. Equipment you need 5 days the Standard DeLuxe, Mini- under any and all conditions absolutely ature DeLuxe, Precision without cost or obligation. Accept this DeLuxe, SilCor and trans- challenge to duplicate Toledo's amazing mitting lines. Standard performance and absolute dependabili- offered for every ty at any price. Write for folder giving types are complete details of free trial offer, requirement and in three prices and descriptions of Toledo's sen- different price classes. sational, advanced 1935 equipment. Ask for Bulletin 1002 TOLEDO SOUND EQUIPMENT LABORATORIES AMERICAN TRANSFORMER Formerly Bud Speaker Co. COMPANY 1134 JACKSON STREET TOLEDO, OHIO, U.S.A. 177 EMMET ST. NEWARK, N. J.

www.americanradiohistory.com 572 RADIO NEWS FOR MARCH, 1935

Po,

A C R R.1 1 3 6 COMMUNICATIONS RECEIVER THE SERVICE BENCH ZEH BOUCK

THE DAY'S WORK is also caused by a defective 6Y5 tube. If the set draws excessive Starting off this month with current, and plate the meat of voltage is low, one the service business -notes from the field of these difficulties is invariably the cause. The set should -we have the following data on the Ma- show a reading of 7 jestic 500: amperes at 230 volts when properly adjusted. When testing for `B' Service Notes on the Majestic 500 voltages, the bottom cover of the set need Morris Chernow, New York City, sends not be removed. Simply put the positive The ideal receiver for the Amateur and therDX us the following data on side of the meter to - Short Wave (and Broadcast Band) listener! The the above re- the i.f. trimmer con ACR -136 is a seven tube All -Wave Superhet ceiver: "There are three common ailments denser terminal on top of set. covering 15 -550 meters (540 -18,000 K.C.). peculiar to this model set. Two of them "If the receiver sounds okay with the It is packed with attractive features but low in are quite baffling when first encountered, cover off, but becomes distorted upon re- price. Features Pre-selection, true A.V.C., as all voltages read normal on test. If the placing, especially on low volume, tap the Front panel band- switching, mechanical band- set suddenly stops when a light is metal spider of the speaker lightly spread system, and separate ri. and turned down- ai. gain on or off in wards, recentering controls. Has low image- frequency response, the apartment, and is brought cone. The pressure of and high signal -to -noise ratio. Exceptional for back into operation by shutting off the the top cover causes the speaker to strain tonal fidelity and for unusual selectivity. Has power switch for a moment, the remedy out of center. New sets come that way separate beat oscillator switch For copying code is to short out the a -v -c resistor in the grid from the factory because the sets are tested signals. Speaker is built -in and jack is pro- return circuit of the 6A7 tube. Short - with the cover off and then packed im- vided on front panel for phones, automatically circuiting this resistor has no effect on the mediately. muting speaker. Circuit is built around the operation "Another famous RCA "Magic Brain." Easy to tune. of the set, and it appears to be speaker trouble is due to wet- Comes complete with built -in power supply and the only remedy for overcoming the ting of the set. Water seeps to the voice tubes at an outstanding low price. Write for paralysis. In later models this resistor is coil connections on the cone, and eventu- FREE descriptive bulletin and quotation. eliminated. It seems that the sudden ally causes corrosion by electrolytic action turning on and off of adjacent electrical (similar to the action on the `B' choke) apparatus causes a current surge which and a test with an ohmmeter shows either FREERòs eading biases the control grid of the 6A7 tube so a complete open or high resistance reading Cadi as to paralyse it completely -until the of a few thousand ohms Resolder the ATALLOG switch is opened and the charge allowed affected lead, and coat with Duco cement Send for your copy of the complete 1935 to leak off. When the set does nothing for waterproofing. ALLIED Radio Catalog -the most valuable book in Radio. Packed with Set- Building Kits; Short but motorboat, although all voltages are "Another chronic trouble, when the set Wave Transmitting and Receiving gear; All - okay, it is due to a primary to a secondary seems alive from the grid of the 6C7 Wave, Dual Wave and Short Wave sets; Sound tube Equipment; Test Apparatus; thousands of parts, short -circuit in the 3rd i.f. transformer. only, but dead from all the preceding etc. Write now! A 20,000 -ohm resistor between the two tubes, is the opening of the 2nd i.f. trans- windings prevents this showing up as a former secondary. Z11. DTARIR voltage discrepancy. The only remedy is "Trouble from squeals and oscillations * ALL-WAVE Superheterodyne * to replace the transformer. The third on lower wavelengths -generally from 1100 Build the new lower- priced ALL -STAR ALL - k.c. up. common source of failure is the opening Change to a tested 6A7 . tube. WAVE JR. Tunes 10.550 meters. A great 5 tube Superhet that can be assembled at an amaz- of the audio coupling condenser going to Some of these tubes when they age seem ing low price. Features Band- spread tuning, the grid of the 42 output tube from to give this trouble. The defective world -wide reception, preadjusted coils, beat - the tube note oscillator, excellent tone quality, etc. Easy triode plate of the 6F7. This is of the will not show up in a tube tester." to build. ALLIED is first with the Foundation Kit at $2.25. Send for our FREE ALL -STAR tubular type, .05 mfd. capacity, located at JR. Wiring Diagram and Parts List. the rear of the chassis under the voltage Continuing with some more-. divider resistor!' Mr. Chernow continues with dope on the - «i E ® RADIO Auto Service Notes I C O R P O R A T I O N Majestic 66 Auto Sets Harry Greenberg of Troy, N. Y., ran "Failure to operate after everything into trouble with the Ford -Zenith when 833 W. JACKSON BLVD., CHICAGO, ILL seems to check okay is invariably due to he attempted to service the receiver in ac- Dept. M open grid return condensers across the cordance wtih the manufacturer's diagram. 300,000 ohm a.v.e. resistors. Please send me: These are of Several hours were wasted before he dis- the small tubular type, (.03 mf.) hanging I FREE RCA -ACR 136 Bulletin. covered that the diagram shows the grid cl FREE ALL -STAR JR. Diagram and Parts across the first two r.f. coils. They open leads to the 6F7 detector -oscillator and the List. due to vibration and of course do not affect 6D7 i.f. tube reversed! CI FREE 1935 ALLIED CATALOG. any of the operating voltages; yet cause "Reception with the Majestic 66 (early) failure in Name operation. When vibrator adjust- and the Arvin models 255 and 160 can be ment is 1 found to be hopelessly difficult, be- improved by installing a switch short - Address cause of excessive sparking at contacts and circuiting the extra bias resistor for DX general erratic behavior (even though it reception. The late 66's have this switch. 1 City State may be a new one or just cleaned and ad- Arvin also will supply more detailed infor- justed), it is probably due to a defective mation on its installation to any service- !YI-t1ffff11- MIME ----MIMI glo -bar resistor connected across the plates man requesting it."- Charles Borden, One- of the 6Y5 rectifier tube. Similar trouble onta, N. Y.

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 Shhh! Shhh! QUIET

/ndiuidua/ /yTESTED wfor NOISE It Banishes Noise For Life! ELECTRAD FIGURE 3 New QUIET THIS MONTH'S SERVICE to substitute 45s for the 182s, 182 -Bs and 183s -all 5 -volt tubes. All that is neces- VOLUME CONTROL SHOP sary is to wire the two output -tube fila- The photograph in this month's heading is particularly interesting-not only because it shows an efficient collection of servicing equipment, but also because it is the shop of a brother serviceman from across the briny- Enrico Costa, of Naples, Italy. We have no data on the instruments shown, but by the quantity, we'd venture Standard Re- placement Unit a guess that the usual oscillators, testers with Power- and analyzers are present if in a somewhat Switch at- unfamiliar form. tached. THIS MONTH'S SALES TIP "Kodak as you go" is a nationally known before was such uncanny might well be applied to the NEVERquietness made possible in a slogan that volume control. A photographic rec- It required a radi- radio service business. cally new engineering principle and individual testing at the factory to assure its amazingly smooth, noiseless operation, which actually improves with use. Current is evenly dis- tributed over the flat outer rim of a rigid Bakelite ring, upon which gently glides a special alloy floating contact shoe. Molded Bakelite case, when mounted, Resis- extends tance ele- only % inch back -panel. m e n t New -type power switch baked on fat outer (approved by underwriters) rim of may be instantly attached Bakelite ring. FIGURE 1 or removed by a single screw. Long, easy -to- ments in series, leaving the hum -control cut aluminum shaft. All standard re- resistor out of the circuit. The bias replacement values. sistor should be changed to 1000 ohms. This helps a lot up here in Canada where Cardon tubes are both expensive and diffi- Mail Coupon for FREE cult to obtain." Descriptive Folder, and 1935 General Floating contact shoe glides over re Catalog of Resistors ststance element The "Ham" Shack for Every Purpose. in straight path. (Continued from page 548) FIGURE 2 %- ord of your big jobs -P.A. installations, etc. age for the tube plates is fed through a -make the finest sort of a sales argument radio -frequency choke coil, attached to a RESISTOR in soliciting similar work. (And you might strap bridging the two plate rods. The send them in to the Service Bench. We'll grid return, with grid leak, is attached to pay for 'em !) The photos of Figures 1, the grid rods by means of a similar strap. 2 and 3, as well as the photo in our head- Tuning such a transmitter is extremely ing this month, help Scribner Brothers, of simple. The plate bridging strap is moved ELECTRAD Schoharie, N. Y., in building up a larger up or down on the rods until the desired ELECTRAD. and more profitable business. And at the frequency is attained. The strap on the Inc. grid circuit is moved up same time cameras sell easily in summer. or down on the 175 Varick St.. We know a number making a. good profit rods until minimum plate current without New York. N. Y. in cameras as a sideline! antenna load is obtained. This indicates Plesee send o 1935 Roeietor Catalog. Chock here for folder on new Cardon Tube Replacements resonance of the grid circuit in respect to QUIET Volume Control. the plate circuit. Under such conditions Name From C. W. Dynes, of Toronto, Canada, the transmitter will operate at maximum sends additional data on replacing Cardon efficiency. Address tubes in Sparton receivers with the more Coupling the antenna to the plate- tuning RN -3 conventional types -"I make it a practice (Continued on page 586)

www.americanradiohistory.com 574 RADIO NEWS FOR MARCH, 1935

II HENYON PRODUCTS . ó lì'll WHAT'S NEW IN RADI© Low Priced WILLIAM C. DORF Signal Generator Universal Receiver tality Radio dealers, servicemen and radio fans The outstanding feature of the new In- will be glad to know of the new Triumph ternational Kadette Jewel four -tube a.c.- ..: model 100 universal signal generator. It d.c. receiver is its striking appearance. The features a continuously variable .. _ r.f. and jewel -like case which encloses the receiver :'." r>'`! i.f. output with a four -step ladder attenu- and speaker is made of bakelite and plaskon ator in conjunction with a multiplier switch

` M , ,;_ . Oil Ingenious design ... wise choice of materials ... large demand ... mass production ... low price consistent witht high quality -that's the story of KENYON All Purpose Amplifier Components. Unapproachable for overall quality in material of this price range. Uniform appearance. Silver - finished cases. Ideal for radio receivers and public address systems when price and quality count. material is Complete line -input and output, class A and available in a wide variety and B; mixing-matching transformers; power of colors. Its appearance is further en- and filament transformers; stepdown trans- hanced by the contrasted grille insets, formers; filter reactors. re- producing semi -precious stones such as agate, moonstone, etc. The set utilizes the and variable control to permit the use of 12A7 type combination rectifier and S:7111001101100111 one of the audio any four continuously variable pentode power tube. It is equipped Ask your Dealer for Catalog describing ranges of output from practically zero to with complete lines. If he cannot supply a built -in antenna and a 5 -inch balanced write us on your business letterhead giv- either 50, 500, 5000 or 50,000 microvolts. armature magnetic type ing his name. The instrument speaker. The cabi- employs fundamental fre- net measures inches high by inches quencies from 100 kc. to 10,000 kc.; 5/ 7/ low long and weighs 33/4 pounds. KenyonTran sform er Co., Inc. harmonics of fundamental frequencies in the fifth frequency band permit operation High -Gain Amplifier to 50,000 kc. It is a.c.- operated and when 840 Barry Street Sound Systems, Inc., introduces a new packed. for shipment weighs 12 pounds line of public address systems which are New and measures 11/ inches by 10 inches by York City 9/ inches. WI DO OUR PURI Amateur Receiver The outstanding features of the new National Company model HRO amateur receiver are: ganged plug -in coils with each coil individually shielded, precision Mr. E. H. Rietzke, President of ganged CREI, and originator of the first thorough course in Practical Radio Engineering. Did You Get Your "Cut" Back Get a Real Raise? known as the series "S ". These power -or amplifiers are available in a number of Of course, it's nice to get back your full different sizes providing from 4/ to 90 salary .... but isn't it a real occasion to re- watts of undistorted power output, to meet ceive a RAISE? Radio business is GOOD .. practically every public address require- and if you're not getting anywhere it's ment. The model PA -100 shown in the your own fault! There's quite a difference accompanying illustration employs three between "just getting along" and working push -pull stages using two 53 type tubes, toward a goal. two 45's and one 80 type rectifier. It is designed to have an overall gain of 78 db CREI Will Help You Get Ahead - condensers with a 'new micrometer dial, and a power output of 4/ watts plus single-signal (crystal filter) as standard 28 db. Its frequency range is 30 to 8000 The foremost engineers in the profession equipment, two pre -selector stages, vacuum - cycles with plus or minus 2 db. The di- will tell you that TECHNICAL TRAIN- tube voltmeter with the instrument cali- mensions of the chassis are 17 inches by is who ING a necessity for those men want brated in R scale of carrier intensity, elec- 774 inches by 6/ inches and it weighs 47 to get the big jobs and the salaries that go tron- coupled, air -padded oscillators, beat - pounds. with them. The man who isn't capable of frequency oscillator and two i.f. stages with better performance than his job requires, Litz wound coils and air -condenser tuned. Midget Equalizing Condenser will never get a chance at more important Nine tubes are employed and the set is The new Hammarlund midget equalizing duties. CREI is no "diploma mill ". Each available with either 2- or 6 -volt a.c. type condenser, measuring only % by % inch student receives individual, conscientious tubes and also in a battery model. is so small and light in instruction. weight that it can be conveniently mounted and supported di- Our courses in Practical Radio Engineering are rectly on the connecting wires. With its available in home- study, residence or both. Your inquiries are invited. 44 -Page Illustrated Booklet will be sent on request

CAPITOL RADIO ENGINEERING INST. Isolantite base, special mica dielectric and Dept. R. N. 3 phosphor bronze spring plates it makes a 141h and Park Road -Washington, D. C. desirable r.f. trimmer condenser and is ap- plicable to numerous other similar purposes.

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 575

Crystal High- Frequency Speaker The Brush Development Company intro- "Here's what I think duces the type T51 piezo -electric "tweeter." The reproduction of the speaker begins at about NATIONAL UNION RADIO TUBES" says Fred D. Kerridge of Minneapolis, Minn.

"So far this year (1934), I have used about 800 of them, and to date, have replaced only two tubes, which is about 400 percent better than any other tube I have ever used. "I am personally SOLD on National Union tubes and I am selling only National Union. a point in the frequency range where the response of the standard dynamic type re- "I have taken advantage of five of your shop producer starts to fall off, and continues equipment offers, and they have certainly upward to approximately 8000 cycles. The been a great help in my work ... thanks to model T51 is intended for use with radio National Union." receivers, where it may be connected across the primary side of the present output Thousands of alert ag- transformer. The "tweeter" measures only gressive Service Dealers 41a inches in diameter by inches deep, have joined the National and it is suggested that where large -size Union plan for better dynamic speakers are used it may be con- service business. Why veniently suspended within the dynamic not you? cone. SEND COUPON TODAY Controls Constant Impedance National Union Radio Corp. of N. Y. RN -335 Broadcast and public -address engineers 400 Madison Avenue, New York City will be interested in the new line of Cen- NATICiNAI. I Tell me about the National Union plan for merchan- tralab "Series II" sound projection con- dising radio service, and free shop equipment. trols which includes constant -impedance RADIO TUBES Name RADIO Street \t t,eAAtNTEFD City State

FREE Parts List - Data - Schematic 1935 RADIO SENSATION! BUILD TARJRYOUR OWM -k ALL-WAVE Superheterodyne ?f A 5 -tube superheterodyne, all-wave re-

T -pad . attenuators, T -pad faders, L -pad ceiver capable of world -wide radio recep- attenuators, gain controls and straight tion. Its range is from 10 to 550 meters. faders. The outstanding characteristics of these new controls are: straight -line atten- Sponsored by 11 world-famous manu- uation over a wide frequency range, con- facturers of radio equipment. stant impedance for the entire rotation, permanent freedom from noise without Send for 1935 184 Page Radio Catalog frequent cleansing and long life. 50 Kit of Parts... . 27 TRY -MO RADIO CO., INC. A New D.C. -A.C. Inverter Oxford 6" Speaker $2.50 The E. D. Nunn Company offers a new Sylvania Tubes $3.95 85R Cortland 5t. New York City d.c. -a.c. inverter operating from 115 volts i d.c. lighting lines and furnishing 115 volts TO a.c. output. This power supply is designed HOW R New C "RCP" - to have a maximum load capacity of 150 LEARN CODE in P ANALYZERS watts at continuous duty and 250 watts Thousands of operators intermittent service. It is easily installed agree no, system of printed sheets can teach LEAD IN VALUE! and requires no adjustments. The vibrator the Cd TELE- R provides 2500 hours of service PLEX hasotaught Code ordinarily to more operators in C MODEL and is easily replaced. The inverter is es- past 10 years than P 5414 all other methods com- pecially adapted to the operation of a.c. bined. YOU can learn radio sets in 110 -volt direct -current dis- Code -or step up your w.p.m. amazingly -this R Complete tricts. surer way. No experience needed. Beginners, amateurs, experienced ops get ahead faster with Teleplex. C $28.95 It doesn't merely "show" you code-it IS Code! P A New Dynamic Type You actually HEAR dots -dashes any speed you want. Sends you practice messages and SENDS BACK KIT Reproducer your own key work, which no other system can do. For quicker license find out about this better way R $24.50 The Rola model F6B 8 -inch dynamic used by U. S. Army, Navy, R. C. A., A. T. & T. and many others. We give you complete course, lend all C type loudspeaker has been redesigned to personal service MONEY -BACK ACCURACY, completeness, fine appearance - equipment, give on P plus convenience and provision for future needs - be economical in price and at the same time GUARANTEE. Low cost, easy terms. Without alt at the lowest cost! What more could any analyser provide obligation write for booklet R. N. 27. to make your radio testing and servicing more satisfactory meet exacting speaker requirements. The s to your customers and more profitable to you? Write Dept. overall diameter of the speaker is 8- inches TELEPLEX COMPANY R RN -s for 1985 Catalog of complete testing equipment. and overall depth 4 inches and net weight 76 Cortland` Street New York, N. Y. C RADIO CITY PRODUCTS CO. 3% pounds. The field coil resistance and P Dept. RN -3. 28 -30 W. Broadway. N. Y. transformer size are optional.

www.americanradiohistory.com 576 RADIO NEWS FOR MARCH, 1935 A. C. power for RADIO PHYSICS COURSE Efficient Radio Operation ALFRED A. GHIRARDI

in D. C. districts Lesson 38. Capacity of Condensers T has been found experimentally by be used in condensers are given in the table actually inserting similar size sheets of on the following page. different materials between the plates of The variations between the low and high a given condenser, that the capacitance limits given in this table are due to pos- of a condenser also depends on the kind of sible differences between the grades and material used for the dielectric. Thus if qualities of representative samples. The the plates of a simple two -plate condenser dielectric constant also changes with the are separated by air and the capacitance is frequency if the measurement is made with say i microfarad, the capacitance will be alternating current. increased to about 2 or 3 mfd. by simply The reason for the fact that various ma- filling the space in between the plates with terials affect the capacitance of a con- a dielectric of paraffined or waxed paper. denser differently when used as the dielec- If the paper is taken out and sheet mica is tric, lies in the structure of their atoms. "e NUNN substituted, the capacitance will increase to The dielectric constant depends on the from 3 to 7 mfd. The ratio of the capaci- number of electrons which can be displaced tance of a condenser of given size having out of their normal positions when under INVERTER some particular material for the dielectric, the influence of an external electric force. CHANGES D. C. voltage to A. C., neces- to the capacitance which theisame condenser It thus depends on the material, for all sary for best radio operation, particularly would have with dry air as the dielectric, materials have different atom and electron with short wave reception. - is called the dielectric constant, specific in- arrangements. Type XR -115 (shown above) Line voltage, 115 volts ductive capacity, or relative permittivity We have learned that the capacitance of D.C. Output voltage, 115 volts A.C. Maximum load, of that material. These names are all used a condenser or capacitor is directly pro- 150 watts, continuous. As high as 250 watts may be used intermittently. Efficiency 80 %. Special to represent this constant, but the first is portional to the total area of the plates models available for other voltages. probably the most popular. Since air has which is exposed to the dielectric, is in- the lowest dielectric constant of the va- versely proportional to the distance between Quiet -Efficient- Warranted rious common insulating materials, it is the plates (thickness of the dielectric) and Simple, convenient, quiet -operating. May be in- taken as stalled easily without extra wiring, expense or dif- the standard and has the arbi- directly proportional to the dielectric con- ficulty. Never requires oiling, adjustment, or service trary value of 1. The dielectric constants stant "k," which depends upon the dielec- attention common to former systems. Fully warranted for one year. Vibration switch, specially de- of several insulating materials which may tric material (see table). veloped for this service, is the only wearing part .. . and it is long -lived and trouble -free, warranted for 90 days -and delivering 2500 hours of service in TABLE OF DIELECTRIC CONSTANTS (k) OF VARIOUS MATERIALS ordinary use-easily replaceable by anyone, at cost of only $3.00. Dielectric Material Material There is a big field for dealers and service engineers Constant Dielectric Constant with this new, truly efficient, trouble -free unit. Air (taken as standard) 1.0 Oil, petroleum 2.0 to 2.2 LIST PRICE-MODEL XR -115 Alcohol 15.0 to 26.0 sperm 3.0 to 3.2 If your dealer does not yet stock it, $ Bakelite, C 4.0 to 8.5 transformer 2.2 to 2.7 order direct, sending dealer's name dielectro 5.0 to 7.5 turpentine 2.1 to 2.3 and address. Dealers -write for dis- micarta 4.5 to 6.0 Paper, insulating, 1.6 2.5 counts. Terms to non -rated concerns or untreated to individuals, C.O.D. Beeswax 3.0 to 3.2 oiled or waxed 2.0 to 3.2 Celluloid 4.0 to 6.0 cardboard, pressboard 3.0 Ceresin Wax 2.5 blotting, porous 5.0 Collodion 3.7 to 4.0 Parafine wax (solid) 2.0 to 2.5 Cloth, oil or varnished 3.0 to 5.0 Phenol composition, moulded 5 0 to 7.5 E. D. N U N N Ebonite (see Rubber, hard) Porcelain 4.0 to 6.0 CO. Fibre, uncolored 5.5 Quartz 4.5 to 5.0 Makers of high voltage inverters for black 7.5 Resin 2.5 Neon Sign Service and Laboratory use. red 5.0 to 8.0 Rubber, gum 2.3

Film, photographic 6.8 soft, vulcanized - 2.0 to 3.0 512 W. Huron St., Dept. 11 Gelatine 4.0 to 6.0 hard 2.0 to 3.5 Glass, window 7.5 to 8.0 Shellac 3.0 to 3.6 CHICAGO, ILL. plate 3 0 to 7.0 Silk 4.6. heat resisting (Pyrex) 5.0 to 6.0 Slate, electrical 6.0 to 7.0 Gutta, percha 3.0 to 5.0 Sulphur 2.5 to 4.0 One of the Isolantite 3.6 Varnish 4.5 to 5.5 SUPREME Marble 9.5 to 11.5 varnished cambric 4.0 Mica, sheet 3.0 to 7.0 Vaseline FIDELITY built up 5.0 to 7.0 2.0 AMPLIFIERS Oil, castor 4.5 to 4.8 Water, distilled 81.0 cottonseed 3.0 to 3.3 Wood: bass, cypress, fir 2.0 to 3.0 High 30 Oil, neatsfoot 3.0 3.2 maple 2.5 to 4.5 Gain Watts to Class olive 3.0 to 3.3 oak 3.0 to 6.1 $36.50 Push- less Pull 250 tubes The capacitance of a condenser having t = separation of the plates in SEND FOR A COPY Uses 2 -56, 2 -57, 2 -50 and 2 -81 tubes any number of plates can be calculated inches (thickness of the dielec- OF OUR NEW PUB- Tapped Inputs and Outputs from the equation: tric between any two adjacent LIC ADDRESS Tone Control and Gain SALES MANUAL Control 2235 X A X k X (N -1) plates). AND GENERAL Mike -phono input switch C = (13) N = total number of plates. CATALOG s Mike Current Supply Built-in mike and phono 1010Xt Example: What is the capacitance of a Hoot No external transformers where C = capacitance in microfarads condenser having 51 plates each 5 by 5 (mfd.) inches? They have a of .1 WHOLESALE MERCHANDISERS, separation inch Inc., k dielectric constant (or specific with air between. 626 Broadway, Dept. N, New = York City inductive capacity) of dielec- 2235 XAXkX (N-1) tric (see table above). Solution: C = _ A = the area of one side of one 1010Xt free I- plate. This is the area actually 2235 X 25 X 1 X (51 -1) exposed to the dielectric (square _ .00279 mfd. 100% SHORT -WAVES inches). 101° X .1 Ans. 52 Pages-50 Hookups ALL ABOUT: Xmitting and Receiving Antennas, Bandapreadiug, Receiving and includes such additional distinguished Foreign Stations, Xmitting Backstage tubes. HOW TO BUILD names as Paul Whiteman, Jessica Drago- "19" Twinplex, 5 and 10 Meter Xmitter, "203 -A" (Çontinued from page 571) nette, Gladys Swarthout and Frank Black. Xmitter, BandepreadDoerle A specially designed trophy known as the Set. How To Get Started in Short Waves, etc., etc. used to search for microphone stars of the Radio City Award, an RCA -Victor re- Send 6c (T. 9. eoin or stamps) for future. Eighteen young performers Ponape. Treatise cent by return will be cording contract and other prizes will go heard over a period of thirteen weeks and to the lucky winning pair. Frank Black's RADIO TRADING CO. Hudson two winners will be chosen. The judges orchestra and John B. Kennedy, the mas- New York I committee is headed by Lawrence Tibbett ter of ceremonies, continue on.

www.americanradiohistory.com 577 RADIO NEWS FOR MARCH, 1935 Multiple Regeneration (Continued from page 545)

image - can be used and in this way frequency interference can be greatly di- minished and perhaps one circuit and one tube saved in the intermediate or low - frequency amplifiers. ilteatasfeete The above reaction systems can, of course, be used also to regenerate low - frequency circuits, for instance, as shown Reistdciak, I used in Figure 6. In this experiment tsseKti an ordinary a.f. transformer, connecting the primary between cathode and ground connections. The resistance, Ra, in parallel to the primary served to control the re- Xew l7c*e action. This arrangement has the follow- the transformers have ing disadvantage: 11=1111111M111111! generally a d.c. primary resistance of 1000 or 2000 ohms. With an anode current of of 1 or 2 The Serviceman's Book of Knowledge 1 ma. it gives a negative bias volts. But varying the resistance Ra va- bias. This, however, can be OP ries this avoided by using a higher series resistance R and giving to the grid a plus bias. Thus the higher negative bias through resistance R and transformer with its shunt Ra, in on combination with a suitable plus bias is required operating What it the grid, will give the Here's what The only com- point of the tube characteristic and will not you get: plete book of its materially by adjustment of SERVICING kind ever pub- be affected descrip- lished. the resistance Ra. Complete by ALFRED A. GH1RARDI the sug- tions and illustra- Covers every I mentioned above that with tions of latest 1935 and BERTRAM M. FREED phase of servicing gested regenerative systems the reaction is testing instru- as it is practised In order to provide ments and ser- and Greafly Enlarged today. Written in not entirely smooth. vicing methods (2nd Revised simple clear, easy - for smoother reaction I tried putting resis- (including cath- Edifion of "Radio Servicing Course ") to- understand tance between the grid and the tuned cir- ode -ray). language. cuits, or between the tuned circuit and the by No radio men are The dif- Trouble - shoot- Supplemented better qualified to common minus, as in Figure 6. ing table of write such a book however, has not been worth Symptoms and than A. A. Ghir- ference, Remedies for over while. FIELD SERVICE DATA ardi, author of simultaneous 500 different com- the famous Radio According to the above, mon receivers, Physics Course, reaction at both a high and a low fre- listed by manu- AND ANSWER BOOK and B. M. Freed. may be possible. facturer and quency in the same tube model number. It's really amazing -the way Ghirardi and Contains the two -tube circuit so much into combined experi- In this way an efficient Freed have managed to pack ence of some of used, as suggested in Figure 7. How to install one convenient book and a supplement. might be service auto is true -they do give you all the es- the biggest and from the results of the experi- and For it modern most successful Judging radios (1935 mod- sential facts you need to know about organiza- ments and research set forth above, it els) complete servicing practice. They've done something service - ever been able to do. They tions. must be also possible to use the cathode with ignition nobody else has illus- by in- wiring diagrams. went out in the field -direct to successful Profusely reaction with directly heated tubes servicemen. They found out what methods trated with dia- serting suitable chokes in the filament Data on quick were good and what were bad -what were grams and photo- lead and elim- what were slow -what were profitable, graphs. circuits, as in Figure 8, either in one location quick, invaluable be very ination of elec- what were unprofitable. Gives or in both. Such a system might trical noises and And after months of investigation, tapping charts and tables useful for portable sets where the weight interference in every source of information available, they for reference. all - entire mass of material to give of must be kept down. broadcast and digested the the No knowledge the wave receivers to you just the dope you want to have, mathematics nec- Another possibility might be to use and in auto radios sort that will help you make more money essary - numer- reaction systems in connection (for every make out of your business -and make it quicker. ical problems are suggested of out for with the so- called band -pass circuits. In and model How to cash in on the new technique worked more car). you. this case, obviously, there are always MODERN RADIO SERVICING will show Everything in it circuits than tubes, but according to the Complete table you how to be a more successful serviceman is practical -you than one circuit can be re- of intermediate than you are today. no matter if you're just can put it to above, more frequencies for beginning or if you're an old hand at the work right away! generated from the same tube. all makes and game. Mr. L. E. T. Branch, in Wireless World, models of super- This is a book you will really have to own. the band width bets, new and It will add hundreds of new tricks to your January 28, 1931, gives old. (Essential in trade and put hundreds of new dollars in formula: alignment work). your pocket. We can't begin to give you the y2 r2 whole story here-but we have a circular that Thorough ex- will. It shows you just exactly what is in this bw = planation of all remarkable new book. And it's free! So tear 2;AL forms of AVC and out the coupon-or drop us a postcard - impedance (for in- Q A V C circuits today now before you forget! This TO: where Y is the coupling -right forward you have ®\, Y wM, for capacity and their servic- may be the biggest step ductive coupling = ing problems. ever taken. Radio & 1 ®P Technical Y , r the resistance of coupling = -) The Supplement, Publishing Co., C,,,w MODERN RADIO 45 Astor Place, the SERVICING tells FIELD SERVICE each coil, assuming both coils having you all about DATA gives you Send for 44Z. New York, N. Y. and the invaluable in- same resistance. constructing fre- free cir- Dept. RN -3 this formula it is apparent that in operating all types termediate From of radio test quency tables and cular '4cQ regenerating one or both circuits the double equipment ac- the unique Please send me your free hump will not be lost. Moreover, the cording to latest trouble - shooting odescriptive circular on MOD- curve may perhaps drop methods; how to dope, together ERN RADIO SERVICING. middle of the handle special with other useful considerably. Of course this question must servicing prob- tables, and an- Name still be investigated, but, anyhow, reacting lems (auto, all - swers to prob- t``Q. tuned circuits may be wave, marine, lems in MOD- Address only one of the two etc.); how to sell ERN RADIO 4 useful, as suggested in Figure 9. your service; etc. S ERVICING. I think the above investigations and re- promising and open a rela- sults are very -If- tively virgin and wide field for experi- A( T T T4`? -* T T T T T T T menters and constructors.

www.americanradiohistory.com 578 aur AR J R * %LL-WAVE Superheterodyne A GREATER SENSATION THAN THE FIRST "ALL- STAR" * ALLIED * LEADS AGAIN -FIRST WITH FOUNDATION KITS I

Build the lower zi' *_I*.:a

www.americanradiohistory.com RADIO--NEWB FOR MARCH, ,1935 579 change in orders which now are delivered tions may readily be logged by reference to to them by a tug boat just before they the settings of the two pointers. enter a port. These orders were formerly The band -spread given by this arrange- given via radio which, of course, was ment is as follows: On the 1.4 to 3.75 quicker and cheaper. The Clevelands Cliffs megacycle band, 360 -degree rotation (100 will find that in the long run they will divisions) is the equivalent to approxi- have to accede to the nominal requests of mately .25 megacycle. On the 3.4 to 9.2 the operators because it will be to their mc. band, 360 -degree rotation is equiva- best advantage to do so. Also, ships after lent to approximately .5 mc., while on the T- leaving Duluth, are not heard from again 8.5 to 23 mc. band. 360 -degree rotation is ROUBLE until they reach their next port of call and equivalent to approximately 1 mc. are quite often overdue because when Lake In the next issue constructional details Superior gets rough they have to hide be- and performance curves will be given. SPOTS hind Whitefish Point. We hope that the owners will not "bite off their noses to spite their faces." The illustration in our heading this Radio in Aircraft month shows the 50 -watt Gamewell -West- inghouse police transmitter WPHI operat- (Continued from page 562) ing on 2490 kc. under Sgt. T. A. Bird. 73 from C. R. The mail man brings airplane is to operate in extremely cold Thompson, who hails from Toppenish, temperatures, the lubricant should be Wash., and although he has a heavy load changed to the lightest grade available, to on his chest, we sincerely believe that avoid congealing, which may render the brighter days are ahead for the radio op. unit inoperable. For constant operation The term, "radio operator" does not neces- in sub -zero temperatures, a vibration type sarily mean that the average operator will "B" eliminator may be preferred, in spite die with a key in his hand. Some opera- of its inherent deficiencies. tors have made successes as radio service- Next, open up all junction and switch men, broadcast men and in the airways. boxes, and check connections; once again, We find some like Charles Vought, who critical soldered joints are touched with a whose past ex- owns a radio store and hot iron as a precaution against crystalliza- perience as an operator is aiding him tion. greatly in the amateur field and in service During the 20 -hour check it will be nec- work. So, therefore, Thompson, we would essary for the airplane mechanics to have suggest that you try these other fields until the shielding harness removed from the shipping conditions improve. . . F. Welch engine in order to get at the spark plugs. (W6LDY) sends best 73 to the gang. He The radioman should, if possible, remove is now situated at Fort Bragg, California. the shielding harness himself ; some me- . If Alfred Latimer will let me have his chanics' helpers seem to regard it as a per- UP and coming service men address, I will be glad to supply him with sonal enemy -it gets in their way. After . . . know inefficient equip- the information he desires. We also the mechanics are through with the engine, hear from Earl Phillips of Trinidad, Colo. replace the shielding harness, making sure ment means lost time, inaccurate Any time we can be of help to you, don't that it has not been damaged, and that all work and unsatisfactory results. be bashful, Phillips, just drop us a line... bonding clips are in place. The same will More and more, they are turn- Well, until next time, and with 73 ... ge apply the magneto shields, and such other ing to the Readrite No. 730 ... GY. electrical engine equipment as may have been inspected or serviced. Tester because it takes the guess Go over the entire shielding, and see that work out of servicing and en- it is not frayed or damaged. The cables ables them to quickly and ac- Browning 35 will normally last about 300 flying hours, spots. The re- curately locate trouble when the harness should be completely The No. 730 -To -Point Tester or replaced, if Point (Continued from page 546) strung, if manifold type, is designed especially for speedy and individual -lead type. Only damaged parts efficient servicing. It is extremely wound" with silver -plated wire which has need be replaced in the meanwhile. flexible. Voltage can easily be checked about 5% lower resistance than copper. The bonding check should be made by in any tube circuit. Also measures The various trimmers and padding or "lag" either of the two methods recommended resistance, capacity and continuity. condensers are also mounted in their rein the preceding installment (ammeter or Tester socket terminals are arranged spective compartments. On top of the buzzer). In addition, touch a hot iron to according to RMA standards. It is "catacomb" is mounted the 3 -gang tuning all soldered joints, especially at the control unnecessary to remove chassis from condenser. surface bonding connections. cabinet when localizing defects. The "catacomb," including the tuning Last, examine the antenna and the coun- This tester includes two meters - condenser, is completely wired, lined up, terpoise system. See that the supports and one for reading AC, the other for DC. and tracked so that the set builder has only fittings are mechanically sound, that the These meters are rugged, compact and to make seven connections to the Tuner. insulators are unbroken, and the wire is not accurate. Separate meter ranges are The unit, as a whole, is insulated from the frayed and flexes evenly; replace rubber made possible by connecting to a single chassis proper by four gum- rubber washers grommets where necessary. If an alumi- pair of jacks and using the selector through which the mounting bolts fit. num mast antenna is used, check it at switch. DC ranges are 15, 150, 300 and The Tuner is then grounded to the main both supports and at the insulation at the 600 volts. (1,000 ohms per volt). chassis at one point only when installed. fuselage. It is good practice to check it Milliamperes are 15 and 150. The AC This precludes the possibility of coupling for cracks every 50 hours or so ; this can voltmeter ranges are 10, 25, 150 and 750. to any of the tuned circuits (with chassis be done by "etching" the metal at the currents) and at the same time gives a critical points where fatigue is most likely Your Jobber Can Supply You eliminates acous- to develop. Etching is done by first clean- cushioning effect which At the dealer's microphonics. (The set ing the surface of the metal thoroughly, *;.60 tical- mechanical net price of 1 builder should take particular care not to and then brushing it with dilute hydro- $ have the front metal panel make metallic chloric acid. Incipient cracks, ordinarily READRITE METER WORKS contact with the Tuner.) The interme- invisible, will show as faint black lines, 141 College Avenue, Bluffton, Ohio ,,,, W diate transformers are also tuned and ad- and can be seen with naked eyes or through justed at the factory so that the set builder a low -power magnifying glass. MAIL COUPON FOR CATALOG will have only to line up the circuits for After the check has been completed and used. all incidental work performed, make the the tubes being Readrire Meier Works The receiver is absolutely single con- crucial test -switch on the receiver and trol, all the tuning being done by means of see how it works. 141 College Avenue, Bluffton, Ohio Send me catalog on Readrite No. 730 Tester and the 3 -gang bank of condensers. Band - The ideal to strive for in servicing air- folder proving Iteadrite leadership. spread is accomplished by a micro -vernier craft radio is to leave the set after each arrangement, the shaft of which rotates a check -up in as perfect condition as possible. Name pointer on a 360- degree dial. This pointer There is no "top" or "major" overhaul in makes 20 complete revolutions while the radio installations, repair work being done Address pointer (attached to the main shaft of the only as needed -but done promptly, and City State condensers) goes 180 degrees. Thus, sta- done thoroughly.

www.americanradiohistory.com 580 RADIO NEWS FOR MARCH, 1935

The Technical mended by set manufacturers for their re- Review ceivers. (Continued. from page 569) 26. Auto Radio Antennas, Filters and causes which required servicing with data Noise Suppressors. The line of Lynch an- on the type of receiver serviced and its age. tennas, filters and ignition noise suppres- -Wave sors especially designed for motor radio All Receiver Problems, by Murray installations. Data G. Clay. Proceedings of the Radio on how to eliminate Club motor radio noise is included. of America, October, 1934. Covers the problems of circuit design, interstage coup- 27. The Autostat Charging Rate Boos- ling systems, antenna coupling systems, coil ter. This folder describes the new Lynch switching systems, acoustic feedback, audio Autostat designed to automatically increase and high- frequency microphonics, "on reso- the charging rate of the automobile car nance" and "off resonance" howls and in- generator by five amperes every time the termediate- frequency and oscillator micro - car radio is turned on, so as to eliminate phonics involved in the design of all -wave danger of running down the car battery receivers. while the radio set is in operation. "Prett Response of the Photronic Cell to Modu- 34. Serviceman's 1935 Replacement Vol- y Soft" lated Light Flux at Audio Frequencies, by ume- Control Guide. Revised list, in alpha- John H. Roe. The Review of Scientific betical order, of all old and new receivers Not that I'm a softie ...but Instruments, December, 1934. A discussion showing model number, value of control with my new shaft of of an apparatus which can be used to study in ohms and a recommended Electrad con- aluminum you can almost and determine the audio- frequency response trol for replacement purposes. "bite" me off with a good of almost any photocell. pair of pliers ... in fact a 57. How to Build a High -Quality Con- few swipes with a file and A Brief Survey of the Characteristics of denser or Ribbon Microphone. The Am- I'm down to the required Broadcast Antennas, by H. E. Gihring and perite Microphone Kit, with which it is The new size. Dr. G. H. Brown. Broadcast News, De- possible to build, easily and quickly, a RADI- Just another refinement cember, high -quality OHM off- that makes it so much easier 1934. Discusses the importance of condenser or ribbon micro- ers smooth- to use me in a replacement careful determination of antenna charac- phone. er attenua- job. And do I work smooth? teristics and analyzes the various factors tion. 65. New 1935 Line of Testing Instru- ... ask thousands of service- which must be taken into consideration in ments. men the world over who al- its design. Information on the new 1935 line ways use CENTRALAB of Supreme testing instruments including RADIOHMS for ALL :their Band Switching for the Transmitter, by the new 5" fan -shape meter, the new jobs. Don't say "Gimme a D. A. Griffin. QST, December, 1934. Cir- Model 333 deluxe analyzer, the low- priced Volume Control." cuit diagram and constructional details of Model 333 standard analyzer and an im- Specify RADIOHMS the a band -switching transmitter proved Model 85 tube tester. next time you to simplify stock up. transmission over several bands. 66. An A.C. -D.C. Tester Which Can Be Rabb Snvie Mw Extending Volume Range. Radio Engi- Built at Home at Low Cost. Information ®ryuldóramrmbrraffhr neering, November, n.rc or 9i,uà s>.+r, aft, 1934. A discussion of about the Supreme 5" fan -shape meter, rec- the importance of suitable volume range tifier and resistor kit for the home kit for for high -fidelity transmission and reception the home construction of an inexpensive and an explanation of the compressor -ex- a.c. -d.c. tester. pander system for obtaining a wide volume range to provide faithful reproduction. 2. 1935 R.F. Parts Catalog. Specifica- tions, illustrations and prices on the new Division of to Plan Eliminate Radio Interference, by line of Hammarlund variable, midget, band - GLOBE UNION MFG. CO. Dr. Alfred N. Goldsmith. Electronics, De- spread and adjustable condensers; trim- cember, 1934. An outline of the plan of the ming and padding condensers, r.f. and RADIOHMS -RESISTORS -SUPPRESSORS R.M.A. to eliminate radio interference and an analysis of the results which have been obtained in other countries where definite March, 1935 page 585 and see the steps to eliminate interference RADIO NEWS Free Technical Special Radio News have been Subscription Offer taken. Booklet Service TURN TO 461 Eighth How to Avenue Read Selectivity and Fidelity New York, N. Y. Curves on a Cathode -Ray Oscillograph, by Kendall Clough. Radio Retailing, Decem- Gentlemen: Please send me, without charge, the booklets or folders I ero yne ber, 1934. Explains how the cathode -ray oscillograph is rapidly have filled in below: is ALL-WAV E ne * superseding many STA other test methods for checking set charac- Numbers MID -WEST Leads teristics and describes many of its more Again/ important uses in servicing. FIRST with FO UNDATIONS for Short -Wave Radio's Newest Sensation The Genemotor-Modern Power System, by G. W. Blessing. Radio Industries, My occupation or connection in radio All -Star Jr. October -November, 1934. Gives circuit and is checked off below. description of the operating principles Serviceman Operating Own Business 5 TUBE and Serviceman Employed By: characteristics of the Carter genemotor Manufacturer SUPER power . supply system for automobile radios. Jobber Dealer KIT Organization How to Get Copies of Articles Servicing Only $2.25 will D D start you build- Abstracted in This Department Jobber ing this great set. Radio Engineer For this small sum you The abstracts of articles featured in this Experimenter can order the ALL -STAR department Laboratory Technician FOUNDATION from MID- are intended to serve as a guide Professional or Amateur Set Builder WEST. Includes 1- drilled Eraydo to the most interesting and instructive Amateur front panel, 2- drilled base, 3- en- ma- Licensed larged schematic diagram, 4- enlarged terial appearing in contemporary magazines Station Operator wiring diagram, 5- pictorial diagram, 6- and reports. These Public Address Work detailed instructions for assembly, etc. Start publications may be with the FOUNDATION and-buy the remaining consulted at most of the larger public li- parts as you need them. ORDER THE ALL - braries I am a subscriber newsstand STAR JR. FOUNDATION TODAY, or send for or copies may be ordered direct reader. FREE wiring diagram and parts list. from the publishers of the magazines mentioned. I buy approximately $ of ''MID -WEST RADIO MART radio material a month. (Please 520 S. State St., Dept. R, Chicago, 111. RADIO NEWS cannot undertake to supply answer this question without exag- Enclosed YOU will you copies or not at all.) me at ALL -STAR of these articles. They are NOT in- geration TION described above. cluded in the RADIO NEWS Free Technical Send me FREE diagrams and Parts List of the Name ALL-STAR JR. Superhet. Booklet Service.. Send me FREE 68 Page Mid -West Short Wave catalog. Technical Booklets Available Address Name 6. Line Voltage Control. Characteris- City State...... Address tics and uses of a voltage regulator PLEASE USE PENCIL AND PRINT, and IN J chart showing the correct Amperite recom- FILLING IN COUPON

www.americanradiohistory.com 581 RADIO NEWS FOR MARCH, 1935 intermediate -frequency transformers, coils of 13 to 200 meters (with broadcast or 10- wave - and coil forms; sockets, shields, chokes and meter band optional), automatic miscellaneous parts for receiving and trans- change switch, continuous band -spread, GET THIS BOOK mitting. built -in monitor, speaker and power supply (or batteries), high- fidelity audio and 3. 1935 Short -Wave Manual. A circular other refinements. AND containing list of contents, excerpts and illustrations from the new 16 -page Ham - marlund Short -Wave Manual with instruc- INCREASE YOUR tions on how to obtain a copy containing constructional details, wiring diagrams and The All -Star Jr. list of parts of 12 of the most popular short -wave receivers of the year. (Continued from page 543) PROFITS 4. A New Short -Wave Superheterodyne. pearance, and it does not in any way look of the Describes the outstanding features like a "homemade" job. standard and crystal type Hammarlund Tests are now being carried on with this "Comet Pro" short -wave superheterodynes of the RADIO NEWS Listen- of receiver in one designed to meet the exacting demands ing Posts and as a result an article will YOURS professional operators and advanced ama- appear next month giving an informal re- FOR teurs for a 15- to 250 -meter code and the reception results obtained as by port of phone receiver, but which can be used as some detailed information on the police, well anyone for laboratory, newspaper, operation of the receiver. airport and steamship use. lOc 5. A 1935 Volume Control and Resistor Catalog. - Data on Electrad standard and replacement volume controls, Truvolt adjustable resistors, vitreous wire -wound fixed Carbon Resistors resistors and voltage di- and adjustable from page 556) viders, precision wire -wound non -inductive (Continued resistors, center -tapped filament resistors, resistor is shown in Figure 2. Note the high- quality attenuators, power (50 and greater density and uniformity in this re- 150 -watt) rheostats and other resistor spe- sistor. cialties. Attaching the pig -tails is another difficult 25. Noise- Reducing Antenna Systems. problem. The new Lynch resistors have a Data on the Lynch transposition type sys- fine metal coating on the ends which pro- tem for both long- and short -wave recep- vides the contact with the carbon resistor; tion and the shielded transmission line type over this the cap is placed, while the pig- system for broadcast use. Explains how tails are a part of the cap. the polycoupler system can be used to make The resistor does not get so hot, as ex- apartment -house and hotel installations at plained above, and so it can stand higher a profit. voltage than old carbon resistors of the ®Radio Service Men! This book The margin of safety is greater 60. Audio and Power Transformers and same size. will increase your profits, because because the size of resistors has not been Choke Coils. Descriptions, circuit dia- in it you will find all of the latest grams and prices of the new AmerTran reduced to take advantage of this property. Tests on this type of resistors have been technical information that is necessary for De Luxe, standard and low- priced Silcor your job how to recognize tube and and chokes for public - conducted for more than a year. The ... lines of transformers and, most important, how systems, amplifiers and radio re- tests consist of applying loads at double set troubles ... address in fine, ceivers. wattage and higher, placing the resistor to solve these problems to get sure them to heat, etc. Here Mechanics of Radio Ser- water, subjecting performance! 67. Practical are some of the results. vice. Information including cost, features The book contains 104 pages . . . and is L. Loading the resistor at double wattage and outline of lessons of the Frank change in resistance crammed with useful information. Com- radio servicing and did not cause any Sprayberry course in In one test several resistors were plete data on all tubes, including types data sheets for modern- value. list of Sprayberry subjected to overloads up to four times 15, 18, 255, 2z2, 46B1, and 182B, izing obsolete test equipment and receivers. 25Ys, the normal load and voltages of 880 volts. and complete descriptions of over 90 As a result, the maximum variation of re- types of tubes. 68. How to Modernize the Supreme sistance was 2 percent and majority of 400 -B. Data Sheet No. 4 of the Frank L. variations were fractions of 1 percent. This is Sylvania's latest service help . . . Sprayberry series of data sheets on how Several resistors were placed in water, and it's yours for 10c! Take the guess to moderize obsolete test equipment and boiling water or live steam, which did not out of tube application! You can if you receivers. impair the units. send for this handy pocket manual. 69. Case Records of Broadcast Receiver One independent laboratory subjected re- Repairs. Gives plan, contents and price of sistors to load and heat simultaneously. the Capitol Radio Research Laboratories' Resistors were heated to 135 degrees Fah- YOURS! for l0cin STAMPS loose -leaf case records of 1500 service jobs renheit and subjected to normal load for 350 hours. The actual temperature of the showing how actual troubles were cor- HYGRADE SYLVANIA CORPORATION rected. Serves as a guide in correcting unit then rose to 193 degrees, due to troubles in all types of receivers and power development of heat caused by the load. Makers of Factories supply units. No change in resistance value was observed, Sylvania Tubes Emporium, Pa. while the old type shows 4 to 10 percent Hygrade Lamps St. Mary's, Pa. 70. Data Sheet on Building an Analyzer variation. Several other temperatures and Electronic SR Salem, Mass. Adapter. Compiled by the Capitol Radio CODE Clifton, N. J. Research Laboratories to show servicemen loads were used. The old type resistors, Products subjected to 200 degrees F. 10 how any analyzer may be brought up to when and percent overload, showed a resistance va- date or how to build a complete, modern riation of 4 percent in 15 hours. this analyzer out of spare parts with a multi - In meter. test the temperature of the resistor rose to 315 degrees F. According to the available 71. Radio Parts and Sets for 1935. A data, it was shown that these resistors THE SET- TESTED RADIO TUBE new Try -Mo Radio Co., Inc., catalogue would burn out if they were subjected to © H. S. CORP. 1934 listing a wide variety of sets, chassis, stand- a temperature of 266 degrees under load. r ard, special and replacement parts, tubes, However, the new resistors were given 100 Hygrade Sylvania Corporation tools, books, public -address systems, ampli- percent overload at a temperature of 200 Emporium, Pennsylvania (A -20) fiers and other electrical equipment re- degrees Fahrenheit for 450 hours. The quired by radio dealers, servicemen, experi- Please send me the new Sylvania Technical maximum variation in this case was 3.6 Manual. I enclose 10e in stamps. menters, set builders, radio operators and percent. With normal load, at the same engineers. temperature the maximum variation was Name 72. The Skyrider Short -Wave Receivers. 2.9 percent during the same time. Describes the Skyrider tuned- radio -fre- In order to determine the presence or ab- Address quency and Super- Skyrider superhetero- sence of noise, cathode -ray tests were dyne -wave receivers designed short and made. These tests show that the new City State built by Hallicrafters, Inc. Feature range unit is practically noiseless. -.I

www.americanradiohistory.com :582 RADIO NEWS FOR MARCH, 1935 Super SKYRIDER -e'eii "

FEATURES Built-in Power Pack and Preselection Speaker No Plug-in Coils 4 Short -wave Bands Less than 3 Microvolts Exceptionally wide Band Sensitivity Speed- Spreadingactually 3 watts Power Output in 7" on 40 Meter Band the Speaker Tone Control WHERE GERMANY'S SHORT -WAVE PROGRAMS ORIGINATE Acclaimed by Short -Wave The large building in the shape of a hemisphere is the modern broadcasting house Authorities Everywhere! for long -wave transmissions. The tiny peaked -roof house at the right contains the studios and short -wave headquarters for the round -the -world transmissions It will do your heart good to read the unsolicited testimonials from these outstanding short-wave personalities: G. A. Joyce (W9RA); Robert Hertzberg, New York Sun; R. S. Kruse, technical editor of R /9; T. P. Jordan, Scranton. Pa.; Rex Munger, Minneapolis and Lt. Corn. R. H. G. Mathews, famous "Matty" of W9ZN. Nunn, Jr., Paul B. Frame, E. Boston, Mass.; The DX Corner Norman C. Smith. Sidcup, England; Radio Let us send them to you, together with complete Club Venezolano, Caracas, Venezuela; C. H. details of this custom- built. "professionally -perfect" Armstrong, Atlanta, Georgia; Bob Morrison, short -wave superheterodyne. (Short Waves) Vancouver, Canada; \V. H. Reeks, Chicago, Illinois; J. Malone, Melbourne, Australia; John W. J. Halligan, Pres. (Continued from page 552) C. Kalmbach, Jr., Buffalo, N. Y.; E. J. Vas- sallo, Hamrun, Malta; R. Lawton, Whitefield, 8 to 16 G.M.T. and on December 20, from England; J. D. Lowe, Colombia, South America; the hallicrafters, inc. C. H. Skatzes, Delaware, Ohio; L. C. Styles, 16 to 24 G.M.T. This was the first of a Ingatestone, 3001 -A Southport Ave., Chicago, U. S. A. England; M. LeFranc, Managua, series of round -the -clock tests. The man- Nicaragua; Joseph M. Malast, Buffalo, N. Y.; agement is Thomas Van Auken, Livingston, Texas; CT2AJ, of the station interested in re- S. Miguel, Azores; H. L. Zeelenberg, Eind- a hallicrafters ytocFuct ceiving as many reports as possible from hoven, Holland; Y. C. Wen, Shanghai, China; listeners -in. Address your reports to Blake H. Page, Chicago, Illinois; M. Mickel - Philips Radio, son, Minneapolis, Minn.; D. R. D. Wadia, Holland. Bombay, India; Hans Priwin, Copenhagen, Denmark; H. S. Bradley, Hamilton, N. Y.; RW59 Transmissions Stanley C. Isaacs, London, England; Ellsworth Dumas, Milledgeville, Illinois; Charles W. An- SEND An official communication from Radio derson, III, Morristown, N. J.; W. W. Enete, For Your Centre, Moscow, states that station RW59 Brazil, South America; R. NVright, Brooklyn, will N. Y.; Russell Leader, San Francisco, Calif.; FREE transmit on a wavelength of 50 meters Edda Rosa. Trinidad, B. \ \r.I.; Oriente I. Nods, NEW COPY (6000 kc.) on Sunday, Monday, Wednes- Saratoga, Calif.; Sam J. Emerson, Cleveland, day and Friday at 21 G.M.T. On Sundays Ohio; ames T. Spalding, Louisville, Ky.; TO -DAY Virgil CC. Tramp, Marshfield. Oregon; Peter 1935 three additional broadcasts take place on a D. Musnicki, Luck, Poland; Walter F. Daboll, We have MOVED wavelength of 25 meters (12000 kc.) at 03 Providence, R. to considerably I.; Frank E. Baier, El Paso, BIG G.M.T., at 11 G.M.T., and at 15 G.M.T. Texas; J. T. Atkinson, Manitoba Canada; LARGER QUAR- George Pasquale, Phoenix, Ariz.; Wheeler T. BARGAIN TERS to give The call letters for the 25 meter station Thompson, Fredericksburg, Va. Harold W. RADIO you FASTER also are RW59. Bower. Sunbury, Pa.; Donald W. Shields, Rose- - S E R V I C ! E ville, Ohio; Geo. R. Johnson, Medford, Oregon; We now occupy Baron V. Huene, Tientsin, China; Heine John- AMPLIFIER over FOUR British Empire Transmissions son, Big Spring, Texas; Taylor W. Gannett, times MORE An official communication Guayaquil, Ecuador; Douglas S. Catchim, SPACE. from the Washington, D. C.; G. W. Twomey, Fort Snell- British Broadcasting Corporation states ing, Minn.; Roland L. Robinson, Richmond, that the Empire short -wave will Ind.; George C. Sholin, San Francisco, Calif.; Entirely New from stations J. Fr' transmit a C. \leillon, Jr., Paris, France; I. V. Tobler, Cover to Cover! on schedule shown in this Fairbury, Nebraska; Felipe L. Saldana, Tlex, month's Time -Table with the provision Mexico; James L. Davis, Savannah, Georgia; Filled with Latest Design Portable. Mobile and Rack and Panel, Public Address Amplifiers, Short-Wave and All -Wave Reeeiver- that GSC may be substituted for GSB, and Henry Spearing, Indianapolis, Ind.; H. Kemp, and Convertors. Inter -Office Call Systems, Test Equipment. Re- Waterbury, Conn. Earl Wickham, Blooming- nod Aeceseories-all at Unbeat GSE may be substituted for GSD or vice oble Rock Bottom P Tubes, dale, N. j.; Paul J. Mraz, Duprie, S. D.; J. F. versa. Edbrooke, Argentina, South America; Donald IWE ARE HEADQUARTERS FORT Smith, Woburn, Mass.; H. Arthur Matthews, HC2RL Transmissions Victoria, Australia; Harold J. I PUBLIC ADDRESS SYSTEMS I Self, Beccles, England; A. B. Baadsgaard, Ponoka, Alberta, "COAST -TO- COAST" Presents a New Line of An official communication from Dr. Canada; John McCarley, Decatur, Georgia; Roberto Levi, Manager of Short -Wave Larry Eisler, Chicago. Ill.; Carl P. Peters, 1935 P.A. AMPLIFIERS Station HC2RL, "Quinta Piedad," states Troy, Ohio; Edward Hughes, Louisville, Ky.; These improvedroved Italo Amore, Bogota, South America Robert modern , that during 1935 the station will transmit Irving, Chicago, Ill.; George H. Fletcher, Y ail-steel btecpl cr on the same frequency (6668 kc.) and al- Gainesville, Florida; Thursten Clarke, Pem- finished howling broke, Bermuda; Hugo Maugeri, Brooklyn, with hg toe ways at the same hours, Sundays from ventilating 5:45 N. Y.; Howard Adams, Jr., Baltimore, Md.; lnodouvres. Available to 7:45 E.S.T., Duncan T. Donaldson, with optional and Tuesdays from 9:15 Kelty, Scotland; F. R. contained input to 11:15 E.S.T. In Curtis, Washington, D. C.; Wm. Schumacher, Miner- Feder" order to stimulate in- Ellis, Kansas; Herman Control terest in the station the management will Freiss, Istanbul, Tur- Combination Out- key; Ned Smith, Nehalem, Oregon; Phillip put. present to the Swanson, New London, Sherman Current writer of each ten thou- Conn.; Moul- NIet.r, Self Contained sandth verification letter a straw hat, made ton, Bergenfield N. JJ Wm. R. Hamilton, ]like" Current Supply, etc.. etc. Vallejo, Calif.; 'James Haley, Seaside, Oregon; Models available for operation from either a 6 in Guayaquil, popularly known as a Dr. F. C. Naegeli, Jackson, Wyo.; Joseph V. Volt Storage Battery, or 110 Volt A. C. Univer- Trzuskowski, sal Models may be operated from both 6 Volts "Panama Hat." Listeners who write for Central Falls, R. I.; Raymond D. C. and 110 Volts A. C. Portable Models, too. verifications should include an Interna- B. Edge, Buffalo, N. Y.; Harry Myers, Bar - Entire tine, ranging in audio output from 5 ranca -Bermeja, South America; Charles S. Watts to 100 Watt, completely described in our tional Reply Coupon for postage to cover Potts, Kernsville, Pa.; R. W. Winfree, Atlanta, FREE catalog shown above. the answer. Georgia; Bertram Baker Corozal, Canal Zone; Buy Direcf from fhe Manufac- Wm. Kochnlein, New York City; Charles Mil- Readers Who Helped Log ler, Covinggtton, Ky.; Wm. A. Oker Cincinnati, Curer and Pay Only One Profit! Sta- Ohio; S. P. Herren, Jr., Haskell 'Texas; Wm. COAST TO COAST tions for This Month's Report T. Arms, Rowe, Mass.; John Gordon Hamp- RADIO CORP. shire, Wimbledon, London; J. F. Fritsch, Bal- 559565 N SIXTH AVE. NEW YORK, N. Y. F. W. Gunn, Gosfield, England; Harry Lee timore, Md.; C. D. Hall, Chillicothe, Ohio.

www.americanradiohistory.com 583 RADIO NEWS FOR MARCH, 1935 . Reactors Calculated from this formula, the depth Saturable of the 194 turn coil will be: YYATllOYVAI (Continued from page 541) a.c. coil depth =.063 + .125 + (1.1 X .0466 X 3) + selected the stamping it is now required (.005 X 4) to find the number of them to be used. The =.063 + .125 + .154 + .02 = .362 in. XR -2o depth of iron to give the required core Since the window in the stamping selected area is found by dividing the area by the is 1.875 inch wide, there is (1.875 - .362) width of one leg. Thus: or 1.513 inch left for the d.c. coil depth. Area of iron COIL FORMS Depth of iron = The d.c. Coil Width of outer leg furnish flux to satu- is the actual depth as there is a The d.c. coil must This not d.c. loss. The actual depth or stack rate the reactor core. The number of stacking length of of iron is found as follows: ampere -turns depends upon the the magnetic path, the number of air gaps, 1.lXdepth of iron. the quality of the transformer iron, and Stack= by the The number of stampings is found by the amount of load being carried dividing the depth of iron by the thick- a.c. coils. The curve of Figure 7 shows how the ness of the stamping. direct of the outer leg of the stamp- alternating current increases with The width value of direct ing selected for the 100 watt reactor is current. Beyond a certain in current is inch. A depth of 1.99 inches is required. current the rise alternating IS of the curve As these stampings are .r inch thick, 12S slow and therefore that part is useful. The d.c. coil should be will give a 2 inch depth. The not very of them to the flat portion actual stack will be 2.2 inches deep. Coil designed to operate up spools should be designed to have / to of this curve. more than the stack. Enough ampere turns should be used in inch depth lines Each a.c. coil will have exactly one half the d.c. coil to produce about 90,000 of the total number of a.c. turns. In the of flux per square inch. This will require of length of 100 watt reactor being designed, about 34 ampere -turns per inch case the the iron. each coil will have 194 turns. of the d.c. magnetic path through there is a To this value must be added 90 times the If unequal coils are used cir- possibility of some of the a.c. flux passing number of joints in the d.c. magnetic d.c. am- through the d.c. leg inducing a high voltage cuit. Thus the formula for the pere -turns is: in the d.c. winding. For short -wave receiver construction is found as fol- d.c. ampere -turns = The wire area and size and experimental work when a small lows: (34Xlength of d.c. magnetic path) + (90Xnumber of joints in the d.c. coil form at a low cost will fill the Maximum magnetic path) requirements. The XR -20 Coil in The length of the d.c. magnetic path is current amperes Forms are made of Steatite, well Area of wire (sq.in.) = (d +2e-3a). 1000 The d.c. flux takes two paths, but the 1 known Low Loss National Dielectric. By referring to a wire table a size will number of joints in only one path need be They are drilled for leads and left be found having an area close to the desired considered. In Figure 6 there are two unglazed to provide a tooth for coil joints. One at the top of the center leg 1 area. dope. Diameter 11/2". Made with For a current of .870 amperes, a wire and one at the top of the outer leg. area of .00087 square inches is needed. Substituting the design figures of the 100 4, 5 or 6 prongs and fit Standard Number 20 wire has an area of .00080 and watt reactor in the above formula, the d.c. Tube -Sockets. List Price, XR -20, $.35. number 19 wire has an area of .00101 ampere -turns are found. square inches. The latter would be pre- d.c. ampere -turns , NATIONAL R -39 COIL FORMS ferable as it will give less heating. Cotton = [34 X (7 + 10% -4-1;)] + (90 X 2) Machinable and drillable because is very satisfactory + 1801 ampere- turns. covered enamel wire =1500 =680 made of R -39, outstanding exclusive for this use. Any number of combinations of current The turns per layer and number of lay- and turns can be chosen that will given the National Dielectric. Length 21/4". ers is calculated from the stamping size, desired number of ampere- turns. The 0 Diameter I1 /2 ". In 4, 5 or b prong diameter of insulated wire and the num- formula below shows that for any given types. List Price, XR -4, XR -5 or XR- of will be a corresponding number of turns. The actual diameter the current there 6, $.75 each. wire with insulation should be multiplied ber of turns. 1 by 1.1 to take care of winding space loss. d.c. ampere -turns List prices subject to 40% discount Hence: d.c. coil turns = maximum direct current when purchased through an author- "F" dimension 1 is to reach ized NATIONAL Distributor. Thus if ampere to be used 1 of stamping- saturation, 680 turns will be used. If .1 per layer Turns = ampere is used, 6800 turns are needed. USE COUPON BELOW diameter of wireX l.1 For practical purposes let us assume that 1 Turns per coil the output of a 45 is to be used to satu- Layers A plate current of 60 = rate the reactor. 1 Turns per layer milliamperes can be drawn from this tube. Thus the 194 turn coil of No. 19 wire Therefore the d.c. coil turns will be 0 wound on a stamping with a dimension F =34 inch will be calculated as follows: 680 COUPON - -- = 11,333 turns O Turns per layer = .060 3/ National Company, Inc. _ 67 turns is found the same way -= The d.c. wire size Malden, Massachusetts .0425 X 1.1 .0467 as for the a.c. coils. The area will be .060 194 amperes divided by 1000 or .00006 square Gentlemen: Layers = -- = 2.9 or 3 layers. inches. Number 30 wire has an area of Please send me your now catalogue No. mailing costs. 67 .0000636 square inches and is the size that 240. I enclose 6c to cover The winding depth of the a.c. coil should should be used. Enameled wire is suitable Name be known as it determines the available for this coil. space for the d.c. coil. Following the same procedure as for the Address a.c. coils, the turns per layer, number of a.c. coil depth = layers, and depth of winding can be found. .063 in. space between coil spool and These are respectively 293 turns per layer, core + .125 in. coil spool thickness + 30 layers, and .853 inches deep. 'There (1.1 X insulated wire diameter X will be ample clearance between the a.c. number of layers) + (thickness of coils and the d.c. coil. paper between layers X number of Stray a.c. flux that passes through the layers of paper). d.c. coil will induce a current in it. Hence

www.americanradiohistory.com 584 RADIO NEWS FOR MARCH, 1935

a 1 mfd. condenser across the d.c. coil will to the i.f. frequency, in the antenna circuit, bypass the a.c. Or a single short circuited a .00025 condenser should be placed in se- W3CAB turn of No. 14 wire around the d.c. coil ries with JI and the antenna post, since SAYS! will prevent any induced current in it. the line voltage by -pass condensers have to OSCILLATOR ON G -E Very novel effects can be obtained if the discharge to ground through the attenuator RECEIVER OK short circuited turn is of very heavy wire when the shielded lead is not used. This or if a number of bare wire turns are discharge current may be sufficient to dam- U used. This "lag loop" as such a short cir- age the trap circuit 1.E AG,. unless the small block- RÉA -J\ " a cuited coil is called, will make the action ing condenser is used. Aligning of the of the M d.c. coil very slow. more modern sets should preferably be done ?HE GRA By simple arithmetic the average length using an unmodulated signal, in accord- of turn for either the d.c. coil or the a.c. ance with the manufacturer's recommenda- Oli coil can be calculated. Multiply this by tions T¢ORyIPTIOR as given in service manuals. If mod- OF OOYIF% STOY the number of turns and the total number ulation is used, the modulation percentage REGE'"TOR ROOfy.tNTLYGODE of feet of wire needed will be found. Refer control should be kept about one -third ,iAxrs to a wire table to SE convert this to pounds. "on." The modulation frequency control M ON RRTCOR Summarizing the 100 watt reactor design, may be adjusted to give the most agreeable pç0T1.11T0R A laws the specifications are as follows: note, which will vary with the line voltage. If a double peak is noted on the modula- Core tion note, which may occur with home- i Stamping size -7" x made, universal -wound, coils, it is indica- 5 % "x tive that critical coupling between the sec- 50T" thick ondary and tickler coils has not been Outer legs of stamping $s" wide achieved. The tickler coils should be ad- G -E ALL -WAVE RADIOS are Inner leg of stamping 1/" wide justed, by varying the coupling to the sec - top-notch broadcast and short- Number of stampings-128 dary coils, until only a single peak occurs. wave receivers. Everyone Stack -2.2" A double peak on the high- frequency coils, knows that. But what will in- occurring with or without modulation, is terest the amateur or experi- Coils due to poor image- frequency ratio and is normal menter even more is that they A.C. Coils 194 turns with practically all present -day each superheterodyne receivers are also easily adaptable D.C. Coil 11,333 turns on the ultra -high for frequency bands. The proper C. W. reception. For free in- point for formation Characteristics aligning and calibration is3 the higher or on how to construct highest frequency to which the receiver can and hook up a beat oscillator, 100 watt, 115 volt load be resonated. With some types of receiv- write to .157 to .87 amperes a.c. range, controlled ers, several points may be noted at the by 0 to 60 milliamperes d.c. range. extreme high- frequency limit, due to the characteristics R -163, MERCHANDISE of the beat oscillator used. DEPT. A very weak input signal should be used in Signal such GENERAL Generator cases and the receiver adjusted at the ELECTRIC (Continued from Page 561) point of maximum response, tracking being checked Bridgeport, Conn. over many portions of the band. have an exceptionally uniform strength of The "low- output" switch on the signal oscillation except for the very high fre- generator will probably not be required quency ranges. except for the extreme high- frequency The instrument may be calibrated over bands. If sufficient attentuation is still not the broadcast ranges by setting the modu- secured with minimum output on such lation percentage control to zero and bands, an additional condenser may be -and still bringing the oscillator to zero beat with added from J2 to the 25Z5 plate and the broadcast stations of - known frequency. cathode resistor of the 6A7 may be in- more For the short -wave bands, harmonics of creased to several thousand ohms. Neither calibrations obtained on standard broad- of these changes will be necessary if the cast bands may be tuned in on an all -wave instrument is 'operating normally, but sig- Exact Duplicate receiver and, with the receiver left at the nal generators vary considerably in per- point secured, the oscillator is adjusted to formance with apparently minor differ- REPLACEMENTS a higher range and the calibration point ences in construction. secured. The first harmonic is of course To the large list of exact the fundamental, the second harmonic duplicatereplacement con- will densers contained in the be double the frequency of the fundamen- Parts List new 1935 Aerovox Catalog, tal, the third harmonic, three times the many new types have been fundamental frequency, and added. These are listed in so on. This Cl, C2-Aerovox mica condenser, type separate bulletins avail- job must be carefully done if the calibra- 1467, .002 mfd. able on request. tion is to be reliable. It is wise to spot C3, C4, C7, C8, C9, CIO, C14, C15, C16, in on the curves thus secured at the higher C17, C18- Aerovox cartridge condensers, ì frequency ranges short -wave stations of .1 mfd., 200 volts known reliable frequency. Aerovox Exact Duplicate The i.f. ranges C12, C13 (in one can) -Aerovox dual elec- Replacements are precisely can be calibrated only by harmonics in the trolytic condenser, 8 -8 mfd., type GG2, matched in container de- broadcast band, but if several harmoñics 200 volts sign and general charac- are noted for each low- teristics, to the unite frequency oscilla- C6- Aerovox mica condenser, type 1467, which they replace. Also, tion point the difference in frequency be- .0001 mfd. they provide genuine Aero- tween the harmonics will be the fundamen- Aerovox vox quality Cll- mica condenser, type 1467, and perform- tal frequency and may be obtained with a .001 mfd. ance for lasting repairs. reasonable And any type not listed degree of accuracy. CS-National type SEH335 variable con- may be supplied if you For use in aligning receivers, a shielded denser, 270 send your sample and set degrees, 335 mmfd. description. lead, with the shield connected to J2, JI, J2- Na -Ald pin jacks, with insulating should be used. A dummy antenna which, bushings u for standard broadcast bands should con- R1 -Lynch fixed resistor, 100,000 ohms, sist of an inductance, capacity and resis- watt Write for Bulletin tance in series, should be connected to the R2- Electrad type 203, taper F, volume Complete listings of exact antenna post of the set. For short -wave control, with switch, 500,000 ohms duplicate replacements, to aligning, a 400 -ohm resistor is used instead R3- Electrad type 203, taper F, volume date. Also 1935 Catalog of the standard and a sample copy of dummy antenna. While a control, 500,000 ohms monthly Research Worker. portion of the attenuator resistance be- R4 -Lynch fixed resistor, 500,000 ohms, comes a part of the dummy antenna cir- watt cuit, effect is not of consequence in service R5, R6 -Lynch fixed resistor, 100,000 work. When the receiver to be aligned is ohms, 1/4 watt very insensitive, preliminary aligning may R7 -Lynch fixed resistor, 150 ohms, be done 'with an unshielded lead from J1 watt alone to the antenna post, which will cause R8 -Lynch fixed resistor, 10,000 ohms, 1 . - CORPORATION a decided increase in the signal generator watt - voltage at the receiver. If the receiver R9 -Lynch fixed resistor, 6000 ohms, 1 78 Washington St. Brooklyn, N. Y. under test has a tuned trap circuit, adjusted watt

www.americanradiohistory.com RADIO NEWS FOR MARCh , 1935 585

R10 -Lynch fixed resistor, 500 ohms, yt Official "ALL- STAR" Cabinet watt Electrad type 272W, taper F, volume Fits ALL JUNIOR or SENIOR! Ril- -STAR control, 100 ohms R12- Ohmite power cord resistor, 268 ohms POWERFUL NEW relic R13 -Lynch fixed resistor, 25,000 ohms, jiiiiuuuuiiuiiuuuliii iuuiiuiu,1iiuNliuw, watt SW1 -(See R2) AMPLIFIERS SW2- Toggle switch, s.p.d.t. SW3- Yaxley gang switch, 2, deck- 6 -point by, Tl- General Electric special type T -41/2 neon bulb T2 -6A7 tube T3 rectifier tube Jobber -25Z5 WEB STE R Available Through Your T4 -Pilot light, 3.2 volts, .3 amp. Crowe Name Plate and Mfg. Co. 1 National velvet vernier dial, type B, for 1746 Grace St. Chicago, III. 270- degree condenser, with pilot lamp bracket THE SERIES 358 1 1 National "Radio News Signal Generator" RLEARN IN LOS ANGELES cabinet National "Radio News Signal Generator" 15 WATT CLASS ''A, adio- elevision coils (set of 6) ELECTRICITY -TALKING PICTURES 1 line plug BROADCASTING-Special Limited offer! AMPLIFIER 1 grommet, -inch GOOD JOBS WON BY TRAINED MEN rubber / R. R. coach fare allowed to L.A. Earn living while Miscellaneous screws, wire and spaghetti learning. 30,000 graduates. Latest facilities. No dummy equipment. Free employment service. Est. 30 yrs. Se d tubing pay. oiR. for FREE illustrated Catalog. Tells how to earn good 1 National small 7 -prong isolantite tube NATIONAL RADIO & ELECTRICAL SCHOOL Dept. 3 -RN, 4006 S. Figueroa Los Angeles, Calif. socket i Eby 6 -prong tube socket, base -mounting type 1 Kenyon miniature 30 -henry choke N 1 piece bakelite, 3% inches by 2% inches, / inch thick (for coil mounting) 1 piece 1% inches by 21/2 inches, FREE! bakelite, A new, flexible all- purpose Webster amplifier / inch thick (for line filter mounting) around which a variety of sound systems 1 shielded output lead may be assembled. For auditoriums, churches, schools, clubs, factory and office call systems, "23 Lessons In Radio" and for all indoor installations requiring quality reproduction at an attractive price, the Webster 358 Class "A" amplifier is the With ideal unit. Features a three stage Class "A" circuit distinguished for fidelity and for 13 -550 Meter Superhet skillful minimizing of hum level. Incor- of porates the original Webster "stabilized 5 Issues bias" feature assuring maximum undistorted (Continued from page 547) 15 watts output without the use of a separate $1 bias tube. Provides dual control system for RADIO NEWS at European stations. Poste Parisien on 959 "mixing" both phonograph and microphone, with built -in .microphone current supply. ke., for instance, was held at good loud- Equipped with tone control. Has universal speaker volume from 2:10 -3:05 a.m. one output. Completely contained in a well - We still have a very limited morning with a degree of clarity which ventilated steel case, with tubes and terminal strip easily accessible. Effectively supply of the famous book would have enabled one who was familiar fused for protection. The Webster Class "2_3 Lessons In Radio" on with French to understand every word "A" 358 Amplifier is the logical choice for further reprints spoken. Considering the location where quality installations where fidelity and hum - hand. No receiver used at the time, this repre- free operation are of prime importance. the was Write for detailed descriptive bulletin. will be made. If you want a sents a remarkable bit of reception. It was copy, we advise you to send duplicated, but with somewhat less vol- for it immediately! ume, in the case of two other French stations. CLASS4B''26 WATTS tests, the "2.3 Lessons In Radio" covers For the purpose of further receiver was loaned to two of the RADIO Where higner volume levels and wide range the fundamentals including NEWS Official Listening Post (Broadcast coverage are required, Webster offers the 26 watt Class "B" version of the 358 series. Es- elementary radio theory, Band) Observers and was set up in a sentially the same in appearance, input and output characteristics as the Class "A" unit. radio tubes, principles and suburb of New York City for an all -night Particularly suited for out -door use with mul- DX session. This resulted in a log of over tiple speaker arrangements.', There is a wide construction of receivers, market for this moderately priced powerful thirty foreign stations which included unit. Send for complete details. converters and transmitters, South America, Europe, New Zealand and standard radio symbols, the Australia-all on the broadcast band. Seven WRITE FOR CATALOG! Sound specialists, Engineers, Radio Servicemen, amateur field, and many of these (European) were tuned in be- Dealers and others who are interested in Sound tween 4 -7 p.m., and several South Ameri- installations-write for free bulletin describing other important items. the Series 358 units, as well as. for the valuable cans between 7 -10 p.m. The others were complete Webster listing of Sound Equipment. tuned in between midnight and daylight. covering all types of installation requirements, Get your copy now -it's FREE Submit your Sound problems to Webster On the short -wave ranges, suffice it to engineers for complete recommendations and with 5 issues of RADIO say that stations all over the world, in- advice at no cost to you. Write now! NEWS at $I. cluding Europe, Australia, Japan and Java, were tuned in on the loudspeaker in our tests. RADIO NEWS For the full advantage of high sensitivity WEBSTER a receiver must naturally be highly selec- CHI CAGO tive. In New York City it was found possible to tune in distant stations 10 kc. 3825 W. LAKE CHICAGO, ILL. Dept. A side of each location with no inter- ST. Radio News, Dept. 353 either (0) Please send me Free bulletin covering the ference. Unfortunately space does not per- Series 358 Webster Amplifiers. 461 Eighth Ave., New York, N. Y. mit a more detailed report on the RADIO (D) Please send me the complete Webster me Sound Catalog. I am interested in in- Enclosed find S1 For which kindly send NEWS tests, but the fact remains that had stallations as described in the letter attabhed. of RADIO NEWS and the next 5 issues 10 years ago, forecast such a re- Free copy of "23 Lessons In Radio." anyone, my been (Canada 51.45- Foreign S1.50). ceiver, he would have dubbed "highly Name visionary," to say the least. Name Address Address APRIL ISSUE City State City State Annual S.W. Number

www.americanradiohistory.com 586 RADIO NEWS FOR MARCH, 1935

WHEN S.W. Converter 800, 5CK, Crystalbrook, on 635, and 2UE, CHOOSING Sydney, on 1025, are others that are heard (Continued from page 549) well. At the present time no Japanese A RADIO SCHOOL way of saving prospective stations are being received by the writer, constructors so will not touch time and trouble was to arrange on them. RCA Institutes, with with a Comparing this to its reputation manufacturer to put out a foundation short -wave reception, firmly established by 25 kit I say there are more years ser- consisting of a three -gang condenser and thrills on the broad- vice, is an institution recognized as cast band, for the simple a set of coils to match. This plan is now reason there are an important factor in the radio under way so many new places that one can hear. industry. and it is believed by next month Every country it will be possible to publish the in Europe that has a short- complete wave station can logged constructional article with a be on the broad- Whether elementary radio prin- foundation kit cast band and in available which will consist of the r.f., addition such countries ciples or advanced subjects, sound as Hungary, Ireland, Scotland, Austria, detector and oscillator coils, a 3 -gang con- applications, mathematics or prac- Czechoslovakia, Denmark, and others. tical radio denser to match, the tunable output trans- engineering, RCA In- former stitutes is prepared to give yot the and a drilled chassis -all at a very instruction you need. reasonable price. It is believed that this converter will be capable of providing unusual results, judg- Resident Schools at New fork and Chicago ing from the reception obtained in a long The DX Corner Modern Appara,.us and Laboratory series of tests with the original model of (Continued Equipment -Conveniently Located the converter, using all sorts of broadcast from page 566) -Dai and Evening Classes receivers, ranging 1370 - from the best down to KGFG Oklahoma City, Okla. 100 Tuition Rates $3 to $10 Weekly. some of the ordinary garden variety of 4:40 1310 WCLS Joliet, Ill. 100 midgets -and including both superhetero- 1420 KABC San Antonio, Texas 100 4:50 1200 WJBL Decatur, Ill. 100 Extension courses, for home study dyne and t.r.f. receivers. 1370 KFJZ Ft. Worth, Texas 100 on convenient "no obligation" plan. Upon completion of the final model, a 5:00 1500 WJBK Detroit, Mich. 100 complete 1430 KWCR Cedar Rapids, Iowa 250 Examination and technical advisory set of full -size blueprints will be 5:10 1210 WIBU made Poynette, Wisc. 100 services. Free post -graduate prac- available to constructors who prefer 1500 KGFI Corpus Christi, Texas 100 tical training at resident school with to work from them rather than the smaller 5:20 1370 WHDF Calumet, Mich. 100 drawings in RADIO NEWS. 1420 WLBF Kansas City, Kans. 100 modern equipment under instruct- 5:30 1210 WCRW Chicago, Ill. 100 ing engineers. 1500 KGKB Tyler, Texas 100 5:40 1330 WTAQ Eau Claire, Wise. 1000 Write for Catalog. 1420 WMBH Joplin, Missouri 100 5:50 1210 WJIM Lansing, Mich. 100 P.A. Amplifier First Saturday of Each Month RCA INSTITUTES, 2:10 1210 WBRB Red Bank, N. J. 100 Inc. (Continued from page 557) 2:20 1500 W.WRL Woodside, N. Y. 100 Dept. RN -35 2:30 1210 WGNY Chester, N. Y. 100 When mounted on the rack, the panel can 2:40 1500 WMBQ Brooklyn, N. Y. 100 2:50 1210 WGBB Freeport, N. Y. 100 75 Varick Street be removed without touching the mounting 3:00 1430 WOKO Albany, N. Y. 500 NEW YORK of the chassis itself. 1200 WJBC LaSalle, Ill. 100 The illustration on page 557 shows 1330 KTRH Houston, Texas 100 all three units mounted 3:10 1370 WGL Ft. Wayne, Ind. 100 1154 Merchandise Mart on one rack. At 1210 KFPW Ft. Smith, is Ark. 100 CHICAGO A the pre -amplifier, at B the main am- 3:20 1200 WWAE Hammond, Ind. 100 plifier and at C the power 1120 WTAW College Station, Texas 500 Recognized supply. It is Standard in Radio Instruction Since 1909 desirable to place the power supply 3:30 1310 WLBC Muncie, Ind. 50 well 1210 KASA Elk City, Okla. 100 away from the amplifiers. The lower pho- 3:40 1200 WFAM South Bend, Ind. 100 * it L 1 tographs show the front and rear views 1270 KWLC Decorah, Iowa 100 HERE4 of the pre -amplifier unit. 3:50 1280 WCAP Asbury Park, N. J. 500 1310 WEXL Royal Oak, Mich. 50 It is believed that this amplifier system is 4:00 610 WJAY Cleveland, Ohio 500 Is the Place to Buy suitable for practically any public- address 1270 KGCA Decorah, Iowa 100 job. An 4:10 1280 WTNJ Trenton, N. J. 500 audience of 5000 to 7000 people 1430 * I , rat Ylne YO O WN WBNS Columbus, Ohio 500 can be covered with a 20 -watt amplifier, 1210 KFVS Cape Girardeau, Mo. 100 provided that the right speakers are used 4:20 920 WWJ Detroit, Mich. 1000 UILL and that they 780 KKQGHL Billings, Mont. 1000 TARJR are suitably placed. The 4:30 1380 Pittsburgh, ' Pa. 500 * ALL-WAVE Superheterodyne * * power will be ample for nearly all occa- 1210 KDLR Devils Lake, N. Dak. 100 sions. 4:40 1420 WLAP Lexington, Ky. 100 Here's the Little Brother 1370 WOG * to the famous The fidelity, too, will satisfy most re- Davenport, Iowa 100 ALL STAR! It costs much less to 4:50 1380 WSMK Dayton, Ohio 200 * quirements. 1200 KFXJ * build but it's a Giant in performance. Grand Junction, Colo. 100 * The total power consumption is only 150 5:00 940 WAVE Louisville, Ky. 1000 Even a novice can build it! The most 560 KFDM Beaumont, watts, which makes it possible to use the Texas 500 * amazing -WAVE 5:10 1320 WADC Tallmadge, Ohio 1000 * ALL superhet ever unit on a sound truck. Moreover, * developed for home construction. the 1210 KWTN Watertown, S. Dak. 100 separate units could be mounted in carry- 5:20 1340 WSPD Toledo, Ohio 1000 NOTE THESE FEATURES: ing cases, making the whole outfit 760 WEW St. Louis, Mo. 1000 portable. 5:30 1390 WHK Cleveland, Ohio 1000 * However, it is believed the rack -and 1210 * *Latest 5 tube circuit with multi- purpose tubes. -panel KWEA Shreveport, La. 100 mounting 5:40 880 WSUI Iowa City, Iowa * *Continuous Band Spread will be more suitable for per- 500 * manent installations. 5:50 1230 KGGM Albuquerque, N. Mex. 250 * *AII -Wave Reception from 10 -550 meters * *Pre- Adjusted Coils First Sunday of Each Month * *Beat Note Oscillator 3:00 1290 KLCN Blytheville, Ark. 100 * $eo3 3:30 1440 KXYZ Houston, Texas 500 * *Complete Kit of Parts, 3:50 1400 KTUL Tulsa, Okla 250 * less tubes and speaker 4:00 1260 KPAC Port Arthur, Texas 500 * Foreign DX 4:10 1340 KGDY Huron, S. Dak. 250 * 4:20 1260 KRGV Weslaco, Texas 500 * (Continued from page 563) 4:50 890 KARK Little Rock, Ark. 250 * 5:00 570 KGKO Wichita Falls, Texas 250 * few tips will be given of the stations that 5:20 1010 WNAD Norman, Okla. 500 * 5:40 1260 KUOA Fayetteville, Ark. 1000 * are being received right now. LS2 on 1190 * kc. is heard between 7 and 8:30 p.m. * YV 1RC * on 960 kc. is heard best at 7 p.m. * TGW on 665 kc. has a special DX trans- * mission each Sunday morning after 2 a.m. * HHK, Port au Prince, Haiti, on 920 kc., The "Ham" Shack - can be heard each Friday evening between (Continued from page 57.3) circuit diagram. 7:30 and 8:30 p.m. And last, * list and data, * LR4 on * bitseet . e. * 990 kc. when WBZ fades and LR3 on 950 is * bail5in oat arrangement simple if ..a form of datio brinca Fono- when WRC fades. is depon Unit. morn- * matched -impedance feeders used. Induc- rial layout, The Australians can front be received quite tive coupling is possible but not practical. andd sub panel, and easily during roer information. the spring and autumn If a two -wire matched impedance antenna AddressDeotpt. -85. months. To hear these the best time is system is used, the two antenna feeders from 5 a.m. WHOLESALE RADIO SERVICE until after daylight. 2BL, are attached to each of the plate rods at CO.Ic Sydney, on 855 NEW kc., is perhaps the best equal distances from the tube plates. The YORK I NEWARK ATLANTA loo heard on this coast. 3L0, Melbourne, on feeders closer Shah Ave. 219 Central Ave. I 430 w.Peo,sn-ee st.nw. are brought to the plates of

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 587

the tubes to increase input, and moved MI E nearer the bridging strap to reduce the an- 7-P01 NT tenna load. FELL 20 FEET Dimensions for a typical 5 -meter matched impedance antenna are shown in the ac- ST/LL GOODAS EVER companying diagram. The advantage of ..:AND STILL NO FEEDBACK! this system is that the feeder wires do not have to be cut to any specific length, and Johnston P. A. Service, Oneonta, A SIMPLE, N. Y., writes us: "We are cer- may be several hundred feet without a tainly well pleased with your great loss of efficiency. The feeders used velocity mike (the 7 -point Mike) THIS We believe that no other mike in the New Yorker installation are 125 feet INEXPENSIVE WAY TO emu take the punishment it has and still work. One time it fell long, and connect to a vertical antenna 20 feet to the ground. And atop the highest point of the building. The BRING MOST ANALYZERS dozens of times it has seen rain. We use it in our mobile antenna itself is a piece of 1 -inch galvan- entflt, and it's just as good as ized iron pipe 8 feet 2 inches long, or ever. Also a wonderful help in r nl Mating aeconstieal feed- wavelength. The feeders are run haphaz- back." Guaranteed. Order from as may be seen your wholesaler, or write for ardly to the pipe antenna illustrated Bulletin RN -2. NOT in the picture. THIS 7tMPERITS Cs, m u-en The receiving antenna consists of a simi- 561 BROADWAY 51w YORK lar pipe about 40 feet away from the transmitting antenna. The lead -in connection /4MPERITE is made at the top of the pipe and brought VELOCITY MICROPHONE down to the "shack" on the 41st floor. The receiver is a regular National SRR super -regenerative -type set, which is the WORLD -FAMOUS most popular circuit for high- frequency INTERNATIONALDX work. Because most 5 -meter transmitters modu- The AC -DC ALL WAVE SET are self- excited oscillators, when carrier - io i t i1l5t - lated they "wobbulate" or shift n 4 - ab frequency badly. The transmitter at the 0mM d m W E S T O N Model 666 Type lA Wired, extra $1.75 New Yorker with the long -lines tuning, 6 3 Matched Tubes. 2.25 Broadcast coil...... 75 practically eliminates this fault. A 5 -meter Cabinet 1.95 SOCKET SELECTOR SET NO EXPERIENCE NECESSARY TO BUILD THEM superheterodyne receiver also is available ONE -TUBE ALL WAVE at W2DLG, but is not generally used be- There's no need for you to be handi- BABY-RADIO cause of the greater sensitivity character- with incapable of For AC -DC capped an analyzer plot° kit including- istic of this type set which is made evident analyzing all of today's radio receivers. 5óBinet. coils 40- e4.95 0M. n d diagram& by the heavy background noise from the Wired extra $1.25 A small expenditure will bring it out Electric or l elevator equipment and large neon signs- Battery Tube.'$1.00 of the obsolete class. Head Phone $1.50 all within a few feet of the antenna itself. Ask for Circular No. 160 Weston makes it possible through Experimental Radio Labs. 168 Washington St. Input to the New Yorker transmitter the improved Weston Socket Selector I New York. N.Y. usually is about 40 watts. This is modu- Set which is readily adapted to any New Yorkers can hear them at 177 Greenwich St., Blan, lated by a pair of 250 -type tubes (in Class and all analyzers. Simply attach the The Radio Man Inc. A) which gives a heavy carrier that ade- Socket Selector Unit to the analyzer quately kills the super -regeneration "rush" ...and by use of the colored adapter AUTOMOBILE COMPASS in the receiver and gives ample modulation. combinations you are set for all pres- have quite Have yon r taken the wrong road W2DLG's signals been reported ent day 4. 5. 6 and 7-prong tube re- and traveled ° many miles before dis- on a c your i take? This new AIR- stable when received superhetero- ceivers. PLANE TYPE COMPASS constantly your travel. Sticks dyne type receiver. It's a simple, inexpensive way for Bs 1 ° diamee ONLY $1.95 POSTPAID, luding At W2DLG, stations at Princeton, N. J., scope Compensator.SATISFACTION GUAR- you to broaden the of your ANTEED money refunded E a distance of more than 50 miles are present analyzer. Although, nothing ra iÉhiñSan days. worked consistently. Numerous contacts DEALERS WANTED! you can do with an old analyzer can have been had with stations in New Jersey, ever give you the dependability and HULL MFG. CO., Box 246.4 WARREN, O. New York, on Long Island and Connecti- profit -producing service that the new cut. Regular contact was made with the Weston models illustrated can give. A home stations of members of the Club. bulletin describes all. Send for copy The location has been found to be an ex- ...Weston Electrical Instrument Corp., IienUad cellent one for 5 -meter transmission and 615 Frelinghuysen Ave., Newark, N. J. reception. Occasionally the "gang" at Radio Tubes W2DLG take a transceiver on the roof DE PEN DAB LE LONG LIFE and use a portable antenna that is set on the parapet. Contacts have been made for THE KEN-RAD CORP., Inc., Owensboro, Ky. a distance of 20 to 30 miles. The output from the transceiver is only a fraction of a watt. The greatest need in ultra- short -wave B.S. Degree in Radio, Electrical, Civil, Chemical, amateur communication is the widespread Mechanical or Aeronautical Engineering in two adoption of more stable transmitters! years. Located in an Industrial center with that Engineering atmosphere. Earn board. Low tui- With the general use of arrangements such tion. Preparatory Model 665 Model 698 Department. Enter March, as the type described here, it is possible to ANALYZER June, September, December. Catalog. SELECTIVE SELECTIVE SET SEaVICER practically eliminate frequency modula- - available with ro- -a modern Weston INDIANA TECHNICAL C9LLEGE is tary switch for selec- net servicer at ex- 241 E. Washington St., Fort Wayne. Ind. tion. When this done, generally, it will a tion of ranges - or, tremely low cost. be possible to accommodate great many with pin jacks, in a The outstanding val. more stations on the ultra- high- frequency lower cost model. ue in test equipment. TEP AYEA D band. IN THE SERVICE PROFESSION WITH CASE Calls RECORDS OF BROADCAST RECEIVER REPAIRS Heard ADD 10,000 HOURS to oymm experience! ELIMINATE GUESSWORK By F. W. Gunn, Ox Yard, Gosfield, Hal- Servicing n your WESTON W- DON'T PUZZLE YOUR PROFITS AWAY! stead, Essex, England, on 20 -meter phone: Your work fa already done and recorded for CASE RECOhDN In "CASE W20Q, W3AFW, W2EDW, W2AND, elk Instruments you RECORDS ". This 9x12 leatherette binder CONTAINS 1,500 alpha- W8EOU, W3ZX, CM2MA, ZJ6A, W2ZC, betically and numerically case SUCCESSFULLYLLged COM- VP5BY, W9BGQ, W4ZF, W8FSK, PLETED SERVICE JOBS. Each W2EF, WESTON ELECTRICAL INSTRUMENT tells-symptom-parts Record CORPORATION responsible-elec. W2KR, W3MD, W9USA, SU1SG, W9DXJ, 615 tricot values-location-andl beat Frelinghuysen Avenue, Newark, N. J. placement or repair. Fastest Servicing and W5BCU. On 40 -meter phone: HB9B, Send bulletin on Weston Radio Instruments. technique known, 10S Receiver Makes - 3,000 Models. SUPPLEMENTED HB9AC, F8ZP, LA1BC, LA3G and QUARTERLY FREE for 1 year. Free Name_._..._..__._... Consultation Service. CJ1AH. On 80 -meter phone: PAODK, CAPITOL RADIO RESEARCH $4.75 Postpaid. LABORATORIES INC. PAOIDW and CT2AJ. Address_..___....._ 1503.21st. St. N. W., Wash., D. C. Kindly forward full details on "CASE RECORDS". By Norman C. Smith, Forge House, High City and State NAME Street, Foots Cray, Sidcup, Kent, England, t- ADDRESS on 80 -meter phone: VE1EI, PAOSLB,

www.americanradiohistory.com 588 RADIO NEWS FOR MARCH, 1935

HAF4A, G6NF, HB9B and LA3G. On 80 -meter C.W.: W1GOJ, PAODC, W1BH, OZ5K and RF3U. On 40 -meter C.W.: U1BL, UK3EX, YU7XA, YU7AU, GI2SP, VK3MR, LY1AA, W1HM, HB9AK, AC8AG, LY1J, WET AND DRY ELECTROLYTIC (dut U1CN, LZ9ZB, PK1B0 PAPER AND MICA CONDENSERS and SU6HL. On 40 -meter phone: LU4AB. Says the RCA RECOGNIZED FOR On 20 -meter C.W.: W4EG, W1BEQ, SUPERIOR QUALITY W1DGC, W8KTE, W1EER, WIET, IN ALL CLIMATES Noise Reducing THE WORLD OVER W8MJR, YP5TM, VE1BV, LA4J and ASK FOR LA3I. SOLD BY LEADING World -Wide Antenna JOBBERS EVERYWHERE CATALOG By Harry Lee Nunn, Jr., 227 South OF EXTREMELY To Man -Made Interference SOLAR MFG. CORP. - Church Street, Winston -Salem, N. C., 599BROADWAY COMPACT TYPES on 20 -meter phone: W5AHJ, W6CIN, NEW YORK HANDY FOR SERVICE No more need your short -wave re- W9ATP, W9DEF, W5A00, W9000, W7JW, W5AHJ, HI7G, CM2WW, CM2RA, ception be prey to every passing CM2WZ and W9KVI. Read Classified Advertising By Paul B. Frame, 118 Princeton Street, -It Pays street car- every electrical gadget in Advertisements in this section twenty East Boston, Mass., on 20 -meter phone: cents a word for each insertion. Name your building! The new RCA double - LA1G. and address must be included at the above rate. Cash should accompany all classified doublet antenna says "No !" to man- Keep on sending 'em in, you fellows ! Let's know how far we're all "getting out." advertisements unless placed by an ac- noises credited advertising agency. No advertise- made - and brings in far ments for less than 10 words accepted. Objectionable or misleading advertise- more foreign stations. ments not accepted. Advertisements for Ask your dealer service these columns should reach us not later or engi- than 3rd of 2nd month preceding issue. neer for a Certified Installation. Write Aid to Inventors TECK PUBLICATIONS, INC. 461 Eighth Ave. New York, N. Y. for booklet, "Antenna Facts ". (Continued from page 559) away, never use it, and prevent anyone RADIO A.C. Generator RF $600 else from using it, so that the existing situation in the radio industry might not TEN practical and low -cost - _. changes covering Dodge F be disturbed. 12 -V, Ford T. A., Chevrolet Delco 6 -V, generators into plus installation 100 -500 -watt capacity A. C. Generators, or into 32 -110 -V o In a perfect world, anything like this D. C. motor or generator. Dodge is 500 -W. self -excited. RCA All in one book illustrated with complete simplified in- z Parts Division might be condemned on grounds of public structions and drawings for only $1. Autopower, 410 -P Dept. N policy. In the real and imperfect world in S. Moyne Ave., Chicago. Camden, N. J. which we all must live, there can be no objection to it so long as no one is de- Agents Wanted frauded thereby. There is a chance, how- AGENTS: Stick -on- Window Sign Letters. 500% ever, that incautious inventors may be de- profit. Write today. Metallic Letter Co., 422 N. frauded, or may suffer what amounts to the Clark, Chicago same thing, through use of this policy in connection with royalty contracts. An in- Correspondence Courses ventor of my acquaintance once patented USED Correspondence Courses and Educational Books an improvement in a certain kind of auto- sold or rented. Inexpensive. Money -back guarantee. Write for Free Catalog listing 4000 bargains. Courses Bought.) motive machinery, about which it would Lee Mountain, Pisgah, Alabama. be indiscreet for me to be more specific. If Conclusively proved before- successful, this device would have displaced Electrical Supplies a line of machinery enjoying a sale of some millions of dollars a year. It was INSULATION, wire varnishes, supplies, etc. Send 3c stamp for bulletin. Autopower, 408 -C S. Rayne Ave., RIDER probable, although not certain, that the Chicago. new device would be successful. Accord- Volume Vproves it ingly, the owners of the existing line of Instruction machinery which the new device might GET A U. S. Government Job, commence $'105 -$200 AGAIN.... displace bought the patent and suppressed month. Alen, women, age 18 -53. Are you eligible for it. Nothing has been heard of since. examination? Get our Free Questionnaire -find out. No it obligations whatever. Instruction Bureau, Dept. 251, St. Had the purchasers paid a fair price for Louis, Mo. the patent, I do not think that the in- 946 Models ventor or anyone else could have offered Patent Attorneys 1200 Pages any valid objection. The inventor would have PATENTS -Advice and booklet free. Highest refer- been paid. The buyer's interests ences. Best results. Promptness assured. Watson E. 112 Mfrs. would have been protected. The point is Coleman, Patent Lawyer, 724 9th Street, Washington, that they did not pay a fair price. D. C. Far and away the They most complete and paid, in fact, no price at all. They merely PATENTS. Instruction "How to Establish Your exhaustive work of made a royalty contract, promising to pay Rights" and form, "Evidence of Conception" -sent Free! its kind . no Lancaster, Allwine & Rommel, 414 Bowen Building, service man can a certain number of dollars to the inventor Washington, D. C. afford not to have itl for every machine which they sold using his invention. In fact, they never built or Patents and Inventions sold any such machines, so they owed the INVENTIONS COMMERCIALIZED. Patented or on- All the complications of 1935 sets explained inventor nothing. No one else could build patented. Write Adam Fisher Company, 278 Enright, lucidly, with more schematics, more il- the machines, since the St. Louis, Missouri. luminating diagrams, more data on every purchasers of the VIII. phase of a service man's job than was ever patent had the exclusive right to build before compressed between two covers! them. The inventor was deprived of profit. III Radio JUDGED BY ANY STANDARD, this Man- ual exceeds anything else of its kind in the, Reformers may say that something RADIO ENGINEERING, broadcasting, aviation and world today. should be done about incidents of this kind. police radio, servicing, marine and Morse telegraphy taught thoroughly. All expenses low. Catalog free. Vol. I 1000 pages $7.50. I do not think so. I am old- fashioned Dodge's Institute, Elm St., Valparaiso, Lid. Vol. II 800 pages 6.50 enough to believe that business shrewdness Vol. III 1070 pages 7.50 should not be penalized, even when it Vol. IV 1060 pages 7.50 Salesmen Wanted Vol. V 1200 pages 7.50 works a disadvantage to persons who are Servicing Superheterodynes 1.00 careless or ill- informed. The real remedy is WANTED: County Salesman with car, to demonstrate and service for large Ohio manufacturer. First -Class job. FREE - "Successful Servicing," our that everybody who tries to do business 244 Fyr -Fyter Co., Dayton, Ohio. 8 -page monthly house organ, with should be well informed and careful. There RADIOS -23 models. World's cheapest. Catalog free. valuable data pertaining to RIDER'S is not the slightest real reason, reformers N -20th Century Co., EX., Mo. Manuals, is free to service men. Are you on our mailing list? to the contrary notwithstanding, why the state, or anybody, should protect foolish Song Poems Wanted Money -Back Guarantee people from the consequences of their WANTED: Original poems, songs. MiTM Publishers, foolishness. Protection against misfortunes Studio Building, Portland, Ore. JOHN F. RIDER, Publisher of this kind is in the hands of inventors 125 West 40th St.. New York City themselves. No inventor should sign any Wind Driven Lights kind of royalty contract which does not ELECTRIC LIGHTS -WIND DRIVEN -You buildai provide either for actual use of the inven- them. Write, Wind Motor Electric. Ridgway, Montana:

www.americanradiohistory.com RADIO NEws FoR MAIICH, 1935 589

tion to a minimium amount each year or else for definite financial payments in case the invention is not used. That is the simple and adequate provision against any kind of "pocketing." YOUR In another common question with regard to sale of inventions it usually is the inventor who is at fault, not the purchaser. INVENTION This is the matter of control. Many inventors insist that they will make no deal covering their inventions which does not leave with them control of the business to Protect aHdlNauliaKdíse ít be created. This is very nice if the inventor has his own money to exploit his You may save a great many dollars in legal invention and is willing to risk it. If this fees and perhaps hundreds more in mis- takes avoided by getting this valuable new is not the case, insistence on control usually book by Elmore B. Lyford that gives you means that the invention will not be used the "lowdown" on patents, trademarks or even tried, and that the inventor will and copyrights and "debunks" those prac- tices designed to exploit the inexperienced get nothing. In my own business we have inventor. From the very first step in pro- been required for many years to pass on tecting your idea down to the final stage of hundreds of inventions. We have two in- converting your invention into an income for yourself, Lyford gives you the true facts variable rules. The first is that we will not "straight from the shoulder," in plain, even listen to an account of an invention non -legal language. Get your copy today which has not either been patented or pro- -only $1 postpaid-or send for free descriptive circular. tected by some kind of dated memoranda which will form the basis of a patent ap- RADIO & TECHNICAL PUBLISHING CO. plication should one be decided on. The 45 Astor Place, New York. Dept.RN -3 second rule is that we will consider no in- TUBE TEST VALUES ... vention whatsoever unless the inventor is prepared, under proper terms and conditions, to give up complete control to someone else. The basis of this seemingly harsh rule is Ftl LET RADIO COURSES simple common sense. Nine inventors out of ten, perhans ten out of ten of them, are INSTRUMENT Radio Operating poor business men. Any good business Prepare for Gov't. man who contemplates putting time or license exam. money into the testing or exploitation of Portable Tube Tester, complete Radio Amateur Code an invention wants to be able to control with case, as shown it unhampered by the ideas of the inventor. Radio Servicing If he cannot, the shrewd business man Dealer's net price $24.00 Including short wave receivers. will not put in his money. I think I safely can say to any inventor who expects to control his own invention that the only HERE is the Triplett Tube Tester for which Residen+ Courses users of way to do this is to have enough money Triplett instruments have been Write for Booklet waiting. It is a of his own to exploit it by himself. MASTER TESTER in every New sense of the word. Nothing is left to be desired York YMCA Schools In addition to control, any good business 7 West ilyd Street New York Cite in either appearance or performance. Only four man who buys an invention demands one sockets used for every type of tube. One rotation other item. The value of the invention of the switch instantly indicates interelement CHOICE OF AN EXPERT must be proved ; perhaps not absolutely, shorts and leakages up to 5oo,000 ohms. The NEW POSTAL at least so far is CUSTOM BUILT '35 but as possible without ALL -WAVE RECEIV- actual commercial test. If the inventor has Tests all types of tubes. Large meter. Direct '_ ER was á \ chosen by a reading scale in two colors-RED indicating =- followed the advice outlined in previous / famous Short Wave "Bad" and GREEN indicating "Good ". Line S. n Authority es the officia articles of this series, the nearest possible ... voltage regulation. Makes all short tests, \ `Q- Ell ing Post. approach to this proof already has been cathode e n O . The Postal '35 custom leakage test and individual tests on diodes and 10 ® built for the nouer Short obtained before the patent even was ap- Aerator- nod full wave rectifiers. Easily adapted to any future Commercial plied for, as a part of the precautions ad- features. requirements. No confusion or complications . Sold with a 10 money vised to conserve the time and money of .. WRITE IMMEDIATELYI FOR 6eFREE CIRCULAR NO. no calculations. And no impairment of tube 150 WHICH COMPLETELY DESCRIBES THE POSTAL the inventor himself. SET CHOSEN BY THE FAMOU S. W E PERT values. With only four sockets for every type Next comes the vexed matter of price. of tube, you secure a true test of good and bad IDOSTAI. ©I2AIDIC This usually is a matter on which the in- condition, including the slightest leakages under 135 -J LIBERTY ST. NEW YORK. N.Y. ventor and the purchaser have difficulty in actual tube operation. 6o cycle, loo -130 volts. agreeing, not because either of them is unreasonable, but because both usually are The Master Unit No. 1210 can be furnished gambles and pay in a portable case, as shown above, for outside wirN taking neither wants to Kato LIGHT PLANTS too much for his chance of winning. In servicing or in a counter case as illustrated at are A little gas and a Kato AC plant en- these circumstances, I have found a useful right. There three other Triplett Master ables you to operate AC radios, ampli- Units, all of equal dimensions, for fiers, refrieeratore and other standard house- expedient in a method learned many years every servicing hold appliances. Sizes 300 watts and up. purpose. Write descriptive literature on ago in Nevada in the mining business, the AC `mode. ias $99.00 and up. C expedient of what used to be called a Counter -type Oak Case. Dealer's KATO ENGINEERING CO. Mankato, Minn., U. S. A. A prospector, let us Net Price, Case Only $4.00 AC Generator. 810.00. Converter. for operating AC radios from O. "working bond." say, 18, 32 and 110 volta DC 318.00. has a prospect which he hopes will prove SEE YOUR JOBBER to be a valuable mine. To follow down THE the ore in the vein and see how deep it goes TRIPLETT ELECTRICAL INSTRUMENT CO. and how much of it there is takes money 11i Main St.. Bluffton, Ohio, U. S. A. RADIO to hire miners, install machinery, buy ex- ENGINEERING, plosives and other supplies. The prospector broadcasting, aviation and police radio, servicing, has no money. He is not willing to sell his Write for FREE Folder marine radio telegraphy and telephony. Morse telegraphy and railway accounting taught thoroughly. En- unproved prospect cheaply to some other Triplett Electrical Instrument Co. gineering course of nine months' duration equivalent to Who the three years of college radio work. School established party does have money, for this 116 Main St., Bluffton, Ohio 1874. All expenses low. Catalog free. may mean that he will lose a valuable Dodge's Institute, Oak St., Valparaiso, Indiana the hand, no person Please send me data on the new Triplett mine. On other with 1210 Tester, and other units of the Master money will pay a large sum for a prospect Line BROWNING which may be valueless. UNIVERSAL So they agree on a working bond or op- Name tion. The prospector agrees to give the Address All -Wave Antenna Kit man with money six months or a year to Radio's Greatest Value explore the property. The man with money City Write for Complete In formation agrees to take certain more or less definite RIVARD MFG. CO. State 1014 Madison Ave. Toledo, Ohio steps of exploration. He has an option to buy the property at any time within the

www.americanradiohistory.com 590 RADIO NEWS FOR MARCH, 1935

term of the contract for an agreed price. N9 He can then go ahead and explore the sup- FEDERATED is the logical source posed mine, at his own expense for the ex- of supply for the new, advanced Sensational paying any- 5 ploration work but without YO - OW HETRO thing to the prospector. If the mine proves ,th to be good, he buys it at the agreed price, DE LUXE $3452 If worthless, ILL= TARJR usually considerable. it proves ALL:WAVE Superheterodyne * ALL -WAVE RADIO SPEAKER he abandons his option and no one is the * and loser, except that the prospector now Free information, diagrams and personal TUBES advice to help you build this remarkable knows that he never had the mine he new short wave receiver. Ask for your hoped for. FREE copy of the NEW 1935 CATALOG - This is of utility just released! The newest in Radios, same devin sometimes Parts, Tubes and Sound Equipment at the for uncertain patents. The inventor gives LOWEST WHOLESALE PRICES! the prospective purchaser a year or more Federated Purchaser, Inc. to test the patent's value. If it has no NEW YORK CHICAGO ATLANTA value, the option is abandoned. If it has 25 Park Pl. 1331 So. Michigan Ave. 546 Spring St., N. W. value, the inventor is paid much more Newark Bronx Jamaica Philadelphia Pittsburg than he would have obtained in the beginning by an outright sale. One final word about patent sales agents. SEND FOR YOUR COPY Hundreds of these exist in the United States. Some of them, perhaps all, must Every serviceman and make at least a little money. The idea is short wave fan should have a copy of this NEW to take an agent's contract to sell the in- catalog showing the complete line of Na -AId quality vention of a new inventor, who presum- products. 15 to ably is not equipped to self it for himself See the new and complete line of short wave product, 8 Tube 2200 This plan is not without its appeal to molded of Na -Ald Victron "AA", the material with the sensationally low power factor of 0.0002 at radio fre- Cusfombilt Super METERS common -sense. The average inventor is quencies. not a good salesman. Someone who is a Includes band spread, long wave, broadcast and short good salesman and who is in touch wave coils of all kinds. The most complete line of Amazing New Low Price! with popular priced plugs and connectors, adapters, modern probable markets might do better for him testing accessories, molded cases, switches, dials, knobs, Why be satisfied with anything less than the New analyzer plugs, cables, etc. the first than he could do for himself. Yet I am Retro 8 tube All -Wave Super now offered for Na -Ald items are widely stocked -try your regular sup - time at this truly remarkable price. Uses unique: convinced that the activities of the average plier-if he hasn't them and does not care to get the antenna, R.F. Pre -Selector, Oscillator :Coil Assembly, genuine Na -Ald products order direct from us. big Out typo speaker, and many other features found patent sales agent, admitting not a few ex- only in the highest priced receivers. ceptions, are seldom useful. ALDEN PRODUCTS CO. -AL® Dept. RN -3 715 Centre St. The sound principle is-, -I think, never to BROCKTON. MASS. 7 DAY FREE TRIAL! make an exclusive sales contract with any Convince that regular world -wide, high agent and never to close yourself this a contract recom- COLLEGE fidelity reception, need not be expensive. Try mended by an agent net in your own home for seven days free trial. without independent Degree in 2 Years Foreign Reception Guaranteed or your Money back. advice from your own general attorney, Write NOW for Details! whom you know to be both honest and Complete Radio En. competent. I see no possible disadvantage gineering course in 96 ELECTRICAL INDUSTRIES, Inc. HETRO in allowing a patent sales agent seek weeks. Bachelor of Lincoln Ave. Chicago, Ill., U. S. A. to and Science Degree. Radio 4220 present to you possible offers Cable Address "HETRO" All Codes for your in- (television, talking pic- vention, provided this costs you nothing tures and the vast and provided you have no obligation to ac- electronic field) offers unusual opportunities for cept the offers presented. If the sales agent trained radio engineers. Courses also in Civil, Electrical, Mechanical, Chemical, Aeronautical, Build Your Own does the inventor any good, he is well en- Architectural Engineering; Business Administra- titled to his commission, justly about ten tion and Accounting. Low tuition, low living costs. percent. He is not justly entitled to collect World famous for technical two -year courses. Those WHEATSTONE BRIDGE any part of this prospective commission who lack high school may make up work. Students in from all parts of the world. Located in picturesque For $41.50 advance or to bar the inventor for any hill and lake region of northern Indiana. Enter favorable sale which may come along with- September, January, March, June. Write for catalog. out the agent's assistance. A simple, rugged, wide -range 1F.3S COLLEGE AVE. ANGOLA, IND. Wheatstone Bridge for resistance measurements. Opera- INDEX OF ADVERTISERS tion identical with best labora- Aerovox Corp. 584 McGraw Hill Book Co., Inc. 568 Sensitive, Alden Products Co. 590 Mid -West Radio Mart 580 tory instruments. Allied Radio Corp. 572, 578 Midwest Radio Corp. Fourth Cover Low cost. Kit eas- All -Star Headquarters 569 accurate. American Transformer Co 571 National Company, Inc. 583 ily assembled. Amperite Corp. 587 National Radio & Electrical School 585 Amplivox Laboratories 591 National Radio Institute 529 National Union Radio Corp. 575 Birnbach Radio Co., Inc 592 New York Y.M.C.A. Schools 589 Blan The Radio Man, Inc 592 Nunn Co., E. D 576 Candler System Co., The 592 Postal Radio Corp. 589 Capitol Radio Engineering Inst. 574 Capitol Radio Research Laboratories, Inc 587 RCA Institutes, Inc. 586 Central Radio Laboratories 580 RCA Manufacturing Co. 588 Chicago Radio Apparatus Co. 591 Radio Circular Co., Inc. 592 Classified Advertisements 588 Radio City Products Co. 575 Coast -to -Coast Radio Corp. 582 Radio & Technical Publishing Co 577, 589 Cornish Wire Co., Inc. 578 Radio Trading Co. 576 Corona Hotel 591 Radio Training Association of America 533 Coyne Electrical School 591 Readrite. Meter Works 579 Crowe Name Plate & \ífg. Co 585 Rider, John F 588 Rivard Mfg Co. 589 Sdí_ILLCIáUSS .Au. 630 Nit ;I1.50 Dodges Institute 589 Assernbled $49.70 Scott Radio Labs., Inc. E. H 555 Electrad, Inc. 573 Shallcross Mfg. Co 590 Experimental Radio Labs. 587 Silver, Inc., _McMurdo 531 Mfg. Built around a highly sensitive Federated Purchaser, Inc- 590 Solar Corp 588 Sound Systems, Inc. 591 galvanometer and - Shallcross General Electric Co. 584 Sprayberry, F. L. 568 Resistors. Range .01 ohms to Goldentone Radio Mfg. Co. 592 Supreme Instruments Corp Third Cover 6c in Hallicrafters, Inc. 582 Teleplex Co. 575 11.1 megohms. Send Hammarlund Mfg. Co. 571 Toledo Sound Equipment Laboratories 571 stamps for Bulletin 630 -D. Hetro Electrical Industries 590 Trimm Radio Mfg. Co. 592 Hull Mfg. Co 5S7 Triplett Electrical Instrument Co. 589 Hygrade -Sylvania Corp. 581 Tri -State College 590 Try-Mo Radio Co., Inc. 575 MfG. COMPANY Indiana Technical College 587 HALLCROSS Instructograph Co. 591 Uron Industries, Inc. 591 ólectircaCifealwtinn Lultnntenll, International Correspondence Schools 592 Webster Co., The 585 ,anri.Áccruacte'4liitoil. Kato Engineering Co. 589 Weston Electrical Instruments Corp 587 roo MAC DAGE a Ken -Rad Corporation, Inc., The 587 Wholesale Merchandisers, Inc 576 COL LINGDALfE PA. Kenyon Transformer Co., Inc. 574 Wholesale Radio Service Co 586 Lynch, Inc., Arthur H. 592 Yaxley Mfg. Co., Inc Second Cover

www.americanradiohistory.com RADIO NEWS FOR MARCH, 1935 591

Next month, in the last of this series, we PORTABLE P.A. SPECIAL shall consider what to do if an inventor de- cides to try to exploit his invention for for DANCE BANDS himself, either with personal funds or by CRYSTAL "MIKE" raising capital. Attention Radio Amateurs The National Company just brought out this extremely interesting 12 -page transmitter booklet describing a new semi -portable, six -band, crystal- controlled phone and Iwillli.nanue 40; ;.: : c.w. transmitter with pentode output. The t wavelength ranges covered include the S- your timing' and 10 -meter ultra- short -wave bands and You can take more than a year a a; to pay me back in small monthly payments, starting 60 DAYS after your 10 weeks' training. PAC 7 as shown including cables $125.00 A Pentode Output ÇR Powerful 7 watt amplifier with tone control and tapped impedance TRANSMITTER with Six -Band Excitor switch to match 1 to 6 speakers. All Actual Shop Practice Permanent Magnet Dynamic speak- Here at Coyne you prepare i ers in large cabinets. forabig- payRadiojob byac- z ide w,rrzeSit tual shop work -under ex- New Crystal microphone utilizing la W. S.,pÿéo.,i.,.¿ pert Instructors -on a wonder- v r.aaulareQ PFy..n.... ful outlay of receivers, trans- push -pull principles. mitters,testers and otherRadio equipment. No books, re- Sound Systems, Inc. citations or useless theory. 1311 TERMINAL TOWER, CLEVELAND, O. Many Earn While Learning o I aid my students in finding a spare time job by which they can help pay their liv- NOW READY ing expenses while here. New 1935 Edition Should you need part time o URON Catalog No. 11 work. I'll do my best to get it for you. Only such book published. Invaluable as a Profit Guide to all Service Shops. Lists replacement parts for 18 Vacuum Cleaners and 42 Washing Machines. Thousands the regular 20, 40, 80 and 160 -meter Lifetime Employment Aid of items from largest existing stock. Armature supplies is complete with After you graduate you get lifetime employ- and motor servicing at lowest cost. Belts, bearings, bands. The bulletin sche- ment help and in addition to this I give you a as cogs, casters, couplings, cylinders, gears, rolls, pulleys, matic circuit diagrams, parts data and coil lifetime advisory and review service. special tools and endless material. All is best quality merchandise at immense saving. Pocket Wire Stripper specifications and ordinarily sells for ten Electric Refrigeration -Air Conditioning or Refrigeration Guide included for 25c. cents. In addition to this data there is a Training for this big new companion field to Free to the Trade circuit diagram with parts information on Radio is given you in a complete course -in- ql eluded absolutely without additional cost. Learn the U -R -O -N way, the System that has estab- the construction of a pre -amplifier for use lished so many in a safe, sound and profitable business. with a crystal, condenser or ribbon type Sensational New Plan "Imitated But Never Equaled" microphone. The transmitter is rack -and- There are no strings to my offer. You can start Manufacturers, Exporters and World's Largest Source A pair of RK -20 type at Coyne at any time -then pay for training in of its panel mounted. Sort with -grid modu- small monthly payments spread over a whole URON INDUSTRIES, INC. pentode tubes suppressor year, starting 60 days after your ten -week 1235 W. Sixth St. Cleveland, O., U. S. A. lation are employed in the final amplifier training period - Send coupon for all details. stage. H. C. LEWIS, President o Through a special arrangement, these ELECTRICAL to RADIO COYNE AND RADIO SCHOOL o RADIO CODE booklets are made available, free, 500 S. Paulina St., Dept.35 -3K, Chicago, Ill. Learn at Home with NEWS readers. Address requests to RADIO NEWS, Department N, 461 Eighth Ave., New MR. H. C. LEWIS, President York City. COYNE ELECTRICAL & RADIO SCHOOL Instructograph 500 S. Pauline St., Dept.35-3K, Chicago, Ill. CODE TEACHER IDear Mr. Lewis: Please send me your Big FREE Book, CODE STUDENTS everywhere are and details of your Pay -After-Graduation Plan. turning to Instructograpb, because there is no better way to learn radio code. No Increasing Range of experience necessary. Just "listen" and r Name imitate. Inatructograph sends perfect code. It is available any time regardless Voltmeters of schedule or interfer- IAddress tience. of Inxtruc- Probably the most widely used single test on' explains each step ACQUIRING Mist as a Instructor would do. Instructooroes. Tapes and Book of Instruction for ,ale oo root. instrument of the past ten years is the old City State Terms as month. The ss month FREE f entedr mmonths. Rental Weston Model 489, thousand -ohm -per -volt vpplied on purchase price. Rent for a nth. CODE Il Inetrnctoeraph please, you-BUY IT. Ìf not, d.c. voltmeter, reading 0 -50 and 0 -250 return it. Write for Poll details NOW! No obii tion. volts. Thousands of them must have been INSTRUCTOGRAPH COMPANY, Dept. NR -15 sold, for the writer has seen them in ser- 912 Lakeside Place Chicago, III. vice shops, experimenters' dens, amateur s_ ILL- TAR 41 radio stations and commercial laboratories * ALL-WAVE Superheterodyne * from one end of the country to the other. When it was brought out in the days WRITE of the first "electric" receivers, this meter was perfectly satisfactory because the limit CHI -RAD BUILT READY -TO- Illustrated: LYNCH of most power packs was about 220 volts. HANG-UP. LYNCH HI -FI Duplex Cage, However, FIRST! materials used exclu- G i o n t Killer lead -in with considerably higher volt- sively. For suggestions ALL WAVE Antenna ages being used for receivers, P.A. ampli- Complete and estimate; send System, complete fiers and transmitters, its application be- Foundation sketch of location. $13.75. The Kits comes somewhat limited. ALL STAR Only 227µFYltanc1St..i .IR. FOUN- $2.25 AMPLIVOX LABORATORIES Few owners of these meters seem to DATION in- realize how easy it is to increase the volt- cludes drilled base, Eraydo front panel, enlarged schematic age range to 1000 volts. The idea simply and wiring diagrams and detailed in- is to mount the meter on a small bakelite structions for building, complete, only CORONA HOTEL $2.25. Send your older to CHI -RAD for or other insulating panel, as Ste. Catherine and Guy shown in the quick action. FREE wiring diagram and parts Sts. accompanying illustrations, list. WRITE TODAY. We also have foundations and to add ad- and schematics for the ALL STAR SR. MONTREAL, CANADA ditional multiplier resistors to the 250 -volt

(Next door to His Majesty's Theatre) post. NEW NATIONAL HR O De L %e SUPER To 250 AND ALL SHORT WAVE RECEIVERS RATES: double the 0- -volt scale, use a 250,000 -ohm, 1 -watt, wire -wound resistor; Single, from $1.50 Double, from Send for FREE BULLETINS $2.00 to quadruple this scale, use a 750,000 -ohm, Suites from $4.00 RADIO APPARATUS CO. 1 -watt resistor. CHICAGO Precision resistors with an 415 S. Dearborn St. Dept. RN -7 Chicago, Ill. GEO. V. GREEN, Managing Director accuracy of 1% are required. These are

www.americanradiohistory.com 592 RADIO NEWS FOR MARCH, 1935

quite inexpensive and are an excellent in- BIRNBACH vestment. "Satisfactory Short Wave Reception A piece of ?z -inch bakelite measuring Under Worst Possible Conditions" COMPLETE ,A -Wave 4% by 6 inches is just about right. The // five tip jacks along the bottom are con- 711S. T: venient for quick connections to flexible - HI-FI - ANTENNA test cords. The meter is kept at a con- 1 11 Mls,..o ymPROVES reception. TRADE MARE REGISTERED strengthens signals, re- venient angle by means of long 6/32 ma- duces interference and (High,Fidelitr) DOise on all wavelengths. chine screws acting as inclined feet. Of Complete kit Induces ali parts -new- type coupler. (remdrine no .,ave -chance ANTENNA SYSTEMS switch). wire, Dew-tyre insulator, ac- are located on cessories and instruetione-only .55.7a "We the ground floor of an eleven story building. In this building are number of doctorsoffice MODEL 489 with X-ray equipment, etc., and within one hundred ]lifte Dept. o feet RN-5 for FREE data f us Antenna Kits. Aerial and Ifook. -up is another office building in which are over three hun- Wrrc. M ETER dred doctors with their associated electrical equipment. Standoff Insulate" , ec Reception conditions were so a that in the daytime with antenna. it was practically impossible to hear BIRNBACH RADIO CO., Inc. anytmalhing except local broadcast stations. 145 HUDSON STREET NEW YORK CITY "We have installed two 2055 foot rages and are usin one F .vour - HI -FI Coupling Kits with 240 feet f O :I Giant Killer Cable. EAQ. Madrid. now comes through beautifully, with little background noise. We have checked durmg the o day and find that even if the X -rays are ping. we are able to get sufficient decent reception df iwncililn 250,000 aoshort wave radio work satisfactorily with ao LYNCH OHMB Antenna system." (Name on Request) 75 0,000 "No Radio Can Be Better Than Its 'Aerial- DIESEL POWER OHMS So Aerial Is As Good As a LYNCH Aerial. A COMING AMERICAN INDUSTRY Full Information on Request o O o o o Arthur H. Lynch, Inc., 227 Fulton St., N. Y. 4- a 250V. ,7 50 - PIONEER OF X X t NOISE-REDUCING AERIALS The internal -com- 250 V. 250 V. TIP JACKS bustion engine represents Mfg: man's course, it is a good idea to enclose the `4o FOR supreme triumph whole instrument in a box of some kind, TN of machine power. but. this skeleton construction has sur- Diesel engineers are in great demand. Many vived a great deal of rough handling. are acquiring necessary knowledge through The fact that the top scale readings are spare -time study of this modern I. C. S. Course on Diesel engines. Free booklet] CATALOG Chock full of BARGAINS in RADIO SETS, Long and Short Wave Apparatus, ELECTRICAL ENGINEERING Servicemen's Repair and Replacement Parts, Electri- cal Applicances and hundreds -A Great Industry with a of miscellaneous Specials at TREMENDOUS SAV- INGS. Get this big new Great Future Bargain Book. It's abso- The new I. C. S. Course in Elec- lutely FREE without obligation -just send us your trical Engineering covers this Name and Address on a post card. fascinating field thoroughly. If RADIO CIRCULAR CO., INC. you are just starting or are on 225 Varick St., Dept. R.N., New York, N.Y. the way to a real paying position in this industry, this course brings the knowledge necessary for advancement. You Can Become a- Fast, Capable RADIO OPERATOR at Home MECHANICAL ENGINEERING The CANDLER SYSTEM Makes it Easy for you! If you want to learn code QUICK ask about Junior Course for beginners. If you lack speed ask about Field with a Future Advanced Course HIGH -A SPEED TELEGRAPHING. This I. C. S. Course has meant Whether Beginner, Amateur or Famous Candler op., advancement to hundreds of multiplied by such easy numbers as 2 and Com'1 tell us what ticket ambitious mechanics, you're going up for and we'll Students drafts- 4 makes the mental arithmetic quick and show you how EASY it is to get. McElroy, cham- men, blacksmiths, foundryrnen, CANDLER SYSTEM gives pion 13 years. Wat- patternmakers, apprentices, you Speed, Accuracy and ability son, WIBGL, with and mechanical engineers. You, to Copy Behind -shows you Byrd Expedition. too, will find that enrolling for how to use "mill" in copying Jean Hudson, fast stuff. WSBAK, 9 yrs. an I. C. S. Course is an invest- All questions answered. Save old. Champion of ment in a Bigger Future. Use time and money by sending for world in Class "E." the coupon' FREE BOOK today! CANDLER SYSTEM CO., Dept. N -3 AUTOMOBILE EXPERTS 6343 So. Kedrie Ave., Chicago, III. are always in demand The rapid progress in manufac- High in Quality, Small ture and service of the modern TRIMM in Size, Light in automobile brings new oppor- Neat tunities to thousands of ambi- FEATHERWEIGHT ppearance, erior in tious and forward -looking men. Our There's always a demand for EARPHONES Enneers pwill trained men. The new I. C. S. you. No obligation. Automobile Course will make TRIMM RADIO MFG. CO. you a trained mani The time 1528 Armitage Ave., Chicago, III. ¢o act is now. Use the coupon.

I935 RADIO INTERNATIONAL CORRESPONDENCE SCHOOLS CATALOG All models: Ac -Dc midgets; dual BOX 8283 -P, SCRANTON, PENNA. and world -wide all -wave, farm 30 DAY battery and car -at factory Without obligation, send me full informa- FREE TRIAI ',. prices! Write for 24- tion on SAVE the subject checked below: i page Bargain Catalog 30 GENTS Diesel Power Automobile Course SO Ye m and -DAY TRIAL y Electrical Engineering simple. Every owner of a Model 489 will plan. Prices from R IT E I Mechanical Engineering find the extra resistors very much worth $9.95 UP. hhae.^.Tr ìö ;ov GOLDENTONE RADIO CO. Architecture Drafting Accounting while. 61' Concrete Construction Good English 127 Oakman Bldg., Detroit. Mid-. Reading Shop Blueprints Salesmanship O Civil Engineering Advertising IBUY YOUR PARTS FOR THE Li Gas Engine Operating El Show Card Lettering A New Station in Finland. Radio Civil Service Refrigeration High School Subjects HELSINSKI, FINLAND new 200 - SKYSCRAPER Chemistry D Air Conditioning -A from BLAi -his 3 -tube T.R.F. Receiver miss Highway Engineering Inventing and Patenting watt station located in Sortavala has been described as tsdio News Laboratory Receiver Poultry Farming Aviation Engines in the November and December issues of Radio added to the network of Finnish stations. News. we carry a complete line of parts including Name Age It transmits on the Finnish "common" chassis at low prices. Send for quotations on anything in Radio. We have no catalogue. wave of 400.5 meters. The total number Address INC. of stations in Finland is now nine. THE RADIO MAN, BLAN 177 Greenwich St., N.Y., N.Y.

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