Radio Age 2707- 2708.Pdf
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July J'lu&ust . 192 7 ryou Can't Ca a Load of>1lay on barrow ~ (EITHER can you obtain good musical per J " formance from your receiver unless your audio amplifier can carry the full load of rich tones and overtones. Wherever tone quality is paramount you will find Thordarson Amplifying Transformers. Over thirty manufacturers of leading quality receivers use them as standard equipment. Follow the lead of the leaders. Whether buy ing or building a receiver-if you enjoy music -insist on Thordarson Amplification. You don't have to be water boy THORDARSON THORDARSON R-200 to the PQwer Compact Amplifying Tramformet: THORDARSON The only complete founda A transformer designed for BATTERY tion unit for home-built the musical epicure. The large CHARGER power amplifiers. Contains core of finest silicon steel and power supply transfonner, 2 the high inductance primary 30-henry choke coils, 2 buffer DRY-As dry a.s they make them. I n fact th e winding combine to give this rectifying element is contained in a moisture condensers and center tapped instrument the most perfect proof cartridge. filament supply-all in one transformer reproduction ob SILEN T - N a vibrating parts. Current is rec' compound filled case. Sup tainable_ Has a remarkably plied in two types: R-I71 for tified through a patented electro'chemical wide range of amplification. process. Raytheon rectifier and UX- SAFE - T here is no hazard to rugs or wood 171 power tube, and R-210 Ideal for use with cone type work for there is no acid to spill. T he tubes of for UX-216 B rectifier and speakers. Designed for both the set are safe, even if turned on when the UX-210 power tube. first and second stage ampli charger is in operation. fication. Weight, 2 lbs. COMPACT-Fits into battery compartment Type R-I71, $15.00 easily. Only 214/1 wide, 514" long and 41'4" Type R-2lO, 20.00 Price $8.00 high, overall. EFFICIENT-This charger is always ready for service. No overhauling required. Rectifying element is held in spring clips and can be re placed in thirty seconds. LON G LIFE -The RaytheQn rectifying unit used in this charger is guaranteed by its manu' facturer for 750 hours of full load operation, o r approximately one year's service. The transformer will last indefinitely. Supreme in Musical Performance! CHARGING RATE-2 am peres. TIIORDARSON ELECTRIC MANUFACTURING CO. Tnmsforml!Y S/JI!ClallSis Slnel! 1895 WORLD'S OWEST AND LARGEST EXCLUSIVE TRANSFORMER MAKERS Chicaco. U.S.A. 35" Please lI.Jcntion Radio Aal'l l¥hen 'Writing to Advel·tise1's. RADIO AGE for July-August. 1927 Fetzer Says "You Made My Success Possible" Dear Mr: Smith: I am now Chief Eng ineer of Station W E MC, which I desig ne d a n d built myself from the g round Up . Six m onths were required for the \'i"o rk , and the equipment was designed for 5,000 watts. Prerlous to bu ildin g , his F you're making a penny less than $50 a statIo n I hat! des1iw e ll and built tlVO others. one a 500 , week, clip coupon now for FREE BOOK lI'att stllti(ln. I visited all the Important R adio sta tions or Eur()pe and the eastern haH af the United " ' that tells you about big money opportun St:ltes. with all my expenses paid, before deslgn!n !: O~ ities in RADIO. Better conditions NOW WEi\IC. in order 10 g*, l a.1\ the b.lest ideas. I am vHy happy in my work. f ee l thai I ha'l"e "ar than ever before, in this wonderful new rive d" in the llauio prMession. and I give your industry. The reason is: television accomplished, tranSM thorough tram ing the {'redl!. Atlantic Radio telephony now in use, many other Cordially yours. wonderful advances and inventions constantly widening JOH);, E. FETZER. Station W E:-.rC. the field of Radio- opPortunity. Radio needs trained m en R~rrl~n ~prings, :'I1 ch. NOW! And you can get the necessary training easily and quickly-AT HOME-through new, practical, tested methods that already have helped hundreds g ain s uccess in the Radio field. Yes, right at home in your spare hours, you can get all the knowledge you need for success in Radio--Big Free Book contains all the proof-send for it today! FindOutFREEHowFetzer. Extra Dollars For You Almost at Once Think of earning $15, $20, $30 extra "on the side" every ChambersondHundredsof week without interfering with your regular job, beginning only a few weeks after you start this training! You can my Radio training course is world-famous as the "Training That Pays For Itself." My thoroug h, practical usable train OthersHaveGoined Successin ing methods show YOU how to pick UP t his extra cas h in your spare hours, while all the time you're preparing for the bigger Radio job ahead. In this way, yOU can pay for your RADIO course and put money in the bank, all through profits I teach you to make right after you start with me. And then , Mail Coupon Below For Free Book after only a few months of spare time training, you're r eady to take the bigger Radio positions 1 Send Today For 64-Page FREE "My Salary Three Times Book-Mail Coupon What It Was, Thanks To Chief Send the coupon below, and I'll send you my 64-page book-it's free. Hundreds of You," Says Chambers Engr.At pictures .and facts about the opportunities Dea r Mr. Smit h: H er ewith a p h otograph for big money in the Radio field, how I of myself in m y R adio laborat or y here at stewart help you take advantage of them, the 6 Detroit. I a m ma king a lmost t h r ee t.imes outfits of practice material I send you that what I m a de befor e taking your cou rse, and Warner yoU can build into 100 Radio circuits, and w ill r eceive a n other substantial increase ver y the other pay-raising facts you want to r ead. soon. A i YOU know, ·hl the capacity of Ratlio Engineer No previous Radio eJCperience needed to take h ~re I am iD full charge of Rauio activities apart Branch· advantage of this offer, and no special from the sales depnl'tment. :>0 far I ha'>c met with schooling is necessary. Find out all the f a ct s steady adr3ncement. and ] exped mOfe for the future. .J~IPtII~! for yourself-mail coupon today. 'f he koow lcdge I got from you enabled me to gel \'ill,ere T .lm today. aDd b,,1Iel"e me. J shnll a h~ aY5 be a booster for f our fine school. Address J., E. SMITH, President Sincer ely, E, T" CHAlrBERS. National Radio Institute, Washington, D. C. ~:I~o if.~s) li C1~e. --e -0-U- P- '0- -.. ~~~~~~~~~........ "'-J...tJ.J.: J. E. SMITH, President, National Radio Institute, Dept. G-9t, Washington, D. C. Dear Mr. Smith: Please send me your free 64-page book with all the facts about learning Radio for bigger pay. I understand this places me under no ' ob ligation. Name _._ Address Town .. ____ _ Stak .. Please 111ention Radio Age »-hen. Writing to Adve;"tisel"s . 2 RADIO AGE for July-Augnst, 1927 I I EverlJdalJ Mechanics Chats One outstanding achievement is re' corded this month in the lead article describing the new method of fre quency modulation which is expected Established March, 1922 to be a great boon to the trans mission, reception and manufacturing Volume 6 July-August, 1927 Number 6 interests of the radio industry. Another achievement, though sec CONTENTS ondary in importance, is the an nouncement of the a.c. filament tubes, FOR July-August ISSUE one suited for the Lf. and a. f. stages, Cover Design by A. P. Mehlum and the other only for the detector New Modulation Greatest Discovery.................... 3 stage. Full data on these is recorded By F. A. Hill in this issue. Do You Know What You Are Missing? ............... 4 Amateurs will find two articles cov By Armstrong Perry ering their activities. The first is by •• Building a Vacuum Tube Voltmeter .................... 7 Armstrong- Perry and shows what By K. B. Morcross you are missing if you don't pound The Froth Estate ...................................................... 9 brass (telegraph). The other is a By Joseph Balsamo description of the short wave crystal Spectrum of Radiation ................................. ~ .......... 12 controlled transmitter at 9BHX. In By Elmore B. Lyford addition there is the Amateur Radio Amateur Radio ........................................................ 13 department. Pickups and Hookups ............................................... Fiction lovers wiII revel in the Low Power Crystal Control Transmitter Springy passages to be found in (Blueprint) ........................................................ 17 Joseph Balsamo's present instalment By F. A. Hill of "The Froth Estate." Current Science ...................................................... 27 K. B. Morcross has contributed an Everyday Mechanics .............................................. 31 excellent article on the construction How Bullet-Proof Vests Stop SteeL...................... 32 of the vacuum tube voltmeter for the By Charles Lee Bryson serious-minded experimenter. Correct Broadcast Station List.. ........ 38-40-42-44-46 Both of our non-radio features, Classified Advertisements ...................................... 48 Current Science and Everyday Me chanics, are taking up a bit more space than usual due to the interest Radio Age is published monthly by RADIO AGE Inc. Member: Audit Bureau of Circulations. shown by our readers covering those Publication Office, Mount Morris, Ill. two features. \Ve shall be glad to 404 North Wesley Ave.