TRIPLETT/44t,-Syz& INSTRUMENTS /7 THIN MOLDED CASE NOTE- FULL 5,zE %Y/TM FULL 5 /ZE TR /PLE77 MECHANISM. TR /PL Err MECHAN /SM. ßl LET INSTRUMENT 44SPECS" Minimum case depth. Full standard size rigid mechanism .. no projecting base. Wider shroud strengthens face: focuses attention on scale. Simplified zero adjustment. Sapphire or equivalent jewels. All com- ponent parts finely made and of superior quality. Balanced Bridge Support. Metal Bridges at both ends. Separate Scale Mounting. / - T Doubly Supported Core. OtM[N5/ON5 OYERALL 022 f. /Yurs - O.voea Also available in metal case WITH jr ups K. S. 5789 NOTE: When space is at a premium and for all installations where space is efficiently used. Triplett INSTRUMENT CO. Thin -Line Instruments set new standard of pre. THE TRIPLETT ELECTRICAL coion performance in "condensed" space. For full BLUFFTON, OHIO. U. S. A. details write for Triplett Thin -Line Bulletin to The Instrument Bluffton. Ohio. Triplett Electrical Co ORA NN /1-1 6/-19- ^NECKED ? 5 *- yL 59/7X 1F PROVED iaRgdio WhnwtThin; It the9 know Woce w aox; t at you stetting . now a modern re of ne It you're en r alto 9airbu t Votintter of Warn of end in on your interest in Radio the suse rsgecircuits You can begin cashing olpinR ap Operator.Rodio You QUICK YOU ACT NOW! The Radio repair nevi mr- -IF my business, booming because of the shortage of new sets. baffled xtrs knowledgeaa be f promotiooa' home and auto Radios, offers more opportunities than ever to make $30, $40, $50 a week in full -time extra jobs, or $5, $10 extra a week if you hold your pres- eq r buymely saKe. ent job and fix Radio sets in spare time. Practically all branches of Radio need Technicians, Operators. Radio training can win extra rank, pay in Army, Navy. Find out how I train you at home in spare J. E. SMITH, President time for Radio's opportunities. MAIL THE COU- NATIONAL RADIO INSTITUTE PON BELOW -NOW! Established 27 years IMO He has directed the training of more men for Radio than anyone else. He has helped men already in Radio to get ahead, and men not in Radio to get into Radio and win SUCCESS. Make Me Prove I Can Train You at Home to Be a RADIO TECHNICIAN or OPERATOR CRp. tho coupon and mail lt. Cm certain I con tram pa,a Ili n.ury. ()there, in the Array or Nary. r w rig you at home i 1 your spare time to be a RadloTTechni- pi woolaxl, extra pay, because of their Radio s training. cian. I want to send you a sample lesson free; to exam- Government orders for Radio Equipment have opened new ine. read. See how clear my Course Is to understand jobs for moly In Radio Factories, while many have good EXTRA PAY IN ARMY. See how my Course is planned to help you get a good Civilian Government lobs as Radio Technicians. Open - lob In Radio, a young growing field with a future. You lors. NAVY TOO un't have to give up your present Jean- or spend a In: Of My Course Is Thorough and Practical money to become a Studio Technician. I train you at terne nights In your spare time. I give you a thorough basic training in Paolo Theory and Men likely to go Into military service, soldiers, Charles F. Helmuth. 16 Hobart Ave., Absecon, N. J.. l'ractire whleh enables yin to understood the operation sailors, marines, should mail the Coupon Nowt of every type of Radio e:qu I nnlrnt. I Send writes, "1 tertal Radio in the Marines. Later 1 took practically men got extra rank. extra G hui Learning Radio helps the N. It, 1. Course. Now 1 am my you Rig Kits of Radio Parts with which you hl own boas and get prestige, more interesting duties, much higher P.Y. lobs over other. who thought they had them. I owe Radio circuits and testing equipment. copluct tests and plenty N. It. James Peb- experiments which give you practical experience. That's Also prepares for goat Radio lobe after servire end,. ble er. Mang write., "I was working Ina why many men I train begin to make more money quick- IT'S SMART TO TRAIN FOR RADIO NOW! mirage when I enrolled with N. R. I. I am now Radio ly awi get and hold good jobs. Serviee Manager for the Furniture Co. for their four store.. M- Beginners Quickly Learn to Earn S5 to $10 a Week Extra In Spare Time MAIL THE COUPON -get my FREE Lesson anti 64-page Why Many Radio Technicians I Trained Nearly erery neighborhood offers opportunities for a good book. "Rich Rewards in Radio," at once. See what Itadh at Horne Make $30, $40. SSO a Week part-time Itadio Technician to nicke extra money fixing offers' you as a skilled Radio Technician. Learn how practical my Course really Is. head letters from more The up-to- the -minute Itadlo Technician Radio sets, I give you special training to show you hoar or Operator must in start cashing in on these opportunities early. You get than IGO men I have trained so you can see what they have BOTH a thorough knowledge of Radio. and experi- are doing and earning. atoll Ille Coupon NOW -in an ence working with Radio parts and Radio parts and Instructions for building test equipment such as nient. for conducting experiments that you valuable envelope or paste It on a penny postal. my training gives you. That is why men I trained are give taking advantage of the booming practical wls method Itadlo re,air business with its -senxd yea, half J. E. SMITH, President, Dept. 2KX to get better jobs, to make more money In spare time, sudying my Lessens- or makes Irarn'.ng Itadio at Inner in,t rrvtü.g. fair iva ln¡;, National Radio institute to open their own Radio repair hustnenea. Others fill good -nay Jobe in many of the country's 882 Broadcasting toadied Washington, D. C. Stations, and in Aviation, Police. Commercial, yterine and Government Radio. Loud- Speaker Systems gire g MIA TRAINING MEN FOR VITAL RADIO JOBS GOOD FOR BOTH SAMPLEELE SON FREE J. E. SMITH, President, Dept. 2KX RICH National Radio institute, Washington, D. C. REWA# LN RAD30,4# Dear Mr. Smith: Mail me FREE. without obligation, your Sam- ple Lesson and 64 -page book, "Rich Rewards in Radio," which tells about Radio's spare -time and full -time opportunities and explains your 50-60 method of training men at home to be Radio Technicians. (No salesman will call. Write plainly.) (Please check.) I ) f AM doing fiadlo work. ( 1 1 sea NOT doing Radio work. Name Ago Address ..Stato 2PR RADIO -CRAFT for OCTOBER 1942 THEE IN TT SSVE , lrerv,r,rrntinr: w¡11 NEXT issue November ¡tied list HUGO GERNSBACK The diversified Editor- in- Chief contain a for of0 selected HARRY CONVISER G. ALIQUO the 1lnna 'ing Editor Circulation Manager RA010 BBEGINNER, usual o the ¡n addition Contents OCTOBER, 1942 Issue features. VOLUME XIV -- NUMBER 1 Mailbag 4 Editorial: Deadly Radio Transmission. by Hugo Gernsback 7 DEPARTMENTS, ETC. The Radio Month in Review 8 Mailbag 4 The Radio Month in Review 8 SERVICING RADIO SERVICE DATA SHEET (See Servicing) 16 Practical Transformer Design by Fred Shunaman IO Operating Notes 19 Latest Radio Apparatus 37 Analysis d Alteration of an Analyzer... by Ted Powell 12 Book Reviews 63 Tracking Down Grid Emission 14 Testing Small Power Transformers by H. R. Heap 15 RADIO & TELEVISION How to Make a 23/4"s 4" Receiver by Irving Minton 39 RADIO SERVICE DATA SHEET: Egg- Fertility Radio Tester 40 No. 326 Emerson Model 436 High - Fidelity A.C. Superheterodyne 16 II -Tube Frequency Modulation Receiver by George Francis Baptiste 42 Low -Capacitance A -C Power Supplies Getting Started in Radio by C. W. Palmer 46 by G d Mountjoy and Charles W. Finnigan 18 Which Regeneration Scheme? by M. Harvey Gernsback 43 Receiving Tube Charts 20 Radio Kinks 53 Making A Voltmeter Read Watts. by W. G. Lofstrom 22 Radio Patents Digest 63 B- and C. Battery Eliminator for Service Test Bench by Russell E. Powers 23 Transformerless Power Supplies -Part I. 24 Published by Radcraft Publications. Inc. Publication office: 29 Worthington Street, Springfield, Mass. Editorial and Advertising Offices: 25 West Broadway, New York City. Chicago Advertising Office: RADIO -CRAFT, 520 North Michigan Avenue, Chicago, Ill. RADIO INSTRUCTION RADIO -CRAFT is published monthly, on the first of the month preceding that of date; subscription price is 32.50 per year in V. S. (In foreign countries. Flight Radio School Trains Enlisted Men 26 7Sc additional per year to cover postage; Canada, 50c additional.) Entered at the post office at Springfield as secondclass matter under the act of Signal Corps Training Begun at Illinois Tech 27 March 3, 1879. All communications about subscriptions should be addressed to: 29 Worthington Street, Springfield, Mass., or Director of Circulation. 25 West Broadwa,, New York, N. Y. SOUND * Factors Contributing to Good Recording. by R. A. Lynn 28 Foreign Agents: Sound as an Aid to Navigation by Willard Moody 30 London- Gorringe's American News Agency, 9A Green St., Leicester Square. W. C. 2, England. Devices for Air Raid Warnings 30 Paris -Messageries Dawson, 4 Rue Faubourg, Poissonniere, France. Wide -Range Film Recording Developed for Home Use Melbourne -McGill's Agency, 179 Elizabeth St., Australia. by H. W. Knettell 32 Dunedin-James Johnston, Ltd., New Zealand. ENGINEERING * Text end illustrations of this magazine are copyright and must not be Radio Direction Finders by Willard Moody 34 reproduced without permission of the copyright owners.