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RADIO BROADCAST ARTHUR H. LYNCH. Editor APRIL, 1926 WILLIS K. WING, Managing Editor JOHN B. BRENNAN, Technical Editor Vol. VIII, No. 6 EDITORIAL SCENES H. MARRIOTT is one of the "old men of ROBERTradio" in the United States and his articles about "How ' - Radio Grew Up" seem to please both old and new radio folk. Cover Design From a Painting by Fred J. Edgars The first article in the series he is writing for RADIO BROADCAST appeared in December, 1925. However much we may marvel - - at Frontispiece Listening-in Petyn 642 now at the accomplishments of the amateur in throwing a faint short-wave signal half way around the world with his simple How Radio Grew Robert H. Marriott 643 apparatus, there is still much of the remarkable in the accom- Up plishments of the early radio workers, and there is no one better able to tell about it than Mr. Marriott. There are other arti- What Happened During the 1926 International Tests cles to follow by him. Willis K. 647 Wing A LTHOUGH the International Tests are considerably be- /!. hind us in this rapidly moving radio world, the corres- The March of Radio -J. H. Morecroft 652 pondence from radio listeners all over the United States and from foreign countries still continues to bombard the office. For those who listened in vain for a peep on a foreign wave- The Short'Wave Receiver Contest < 657 $500 length, the review of the results of the Tests on page 647 of this issue should attract attention. A letter just received from The Tube and Its Best Uses Keith Henney 658 a woman in Iowa is especially interesting. "To settle an ar- gument with my husband," she writes, "will you please tell me whether or not the came from The "Aristocrat" Receiver - 664 following program any foreign station?" The program in question came from Bournemouth, and since that station was added to the list at the last minute, Radio Sets for Light Keepers - - - 666 she, among many listeners, did not know they were on. We settled the argument. - - The Listeners' Point of View John Wallace 667 third in the series of Keith Henney's valuable articles THEon tubes appears in this number. The previous two ap- As the Broadcaster Sees It - Carl Dreher 672 peared in the December and February issues of RADIO BROAD- CAST. "The Tube and Its Best Uses" is specially designed to F. F. Drawings by Stratford answer all sorts of questions on the practical use of the tube in radio circuits, and it was written in a large measure to answer definite which came to our office. How a Portable B Battery Transmitter Works inquiries By the Laboratory Staff 678 /DOMING numbers of RADIO BROADCAST will have much of \J interest to every sort of reader. One wishes that space did not us from in this issue some of the Filament Resistance B. Brennan 682 limitations prevent including The Use John of these articles which have been omitted for that reason. In an early number, there will be another of the home laboratory arti- - - - Cutting out the Locals - H. E. Rhodes 686 cles, describing a very useful wavemeter wit,, complete instruc- tions on how to use this valuable device in the home laboratory. is article H. E. Rhodes on de- The Grid and Answers 696 Then there another by wavetraps, Questions scribing a number of valuable types, which will be a great help Coil Dimensions for the "Universal" Receiver to those who are having their own difficulties with a receiver Eliminating the Reflex in the Roberts Circuit which is not selective There will be more informa- How to Calculate Capacity in Series or Parallel enough. A Three-Tube R. F. Circuit with Impedance Amplification tion on short-wave transmitters that subject which has proved widely popular with our readers. Edgar H. Felix has article on how to learn the code which "Now, I Have Found" - - - - 702 written a very helpful many a mystified struggler with the Continental dots and in Cone Speakers Improving Reproduction dashes will find of value. The article C. How to Provide a Counterpoise System great by J. Jensen 4 ' "Can We Forecast Radio from The Silver "Model 1926 Receiver 1 in the April number, Reception A Coil Winder for Diamondweave Coils the Weather?" has stirred up no end of interest and discussion. A Battery Throw-over Switch after the the Associated Press car- Economical Sub'panel Brackets Shortly magazine appeared, ried a story about Mr. Jensen's conclusions. Mr. Jensen's other in the same field to tell Short Wave Stations of the World 708 article has inspired investigators us of their work and we hope soon to print the conclusions of some of these men. A Key to Recent Radio Articles E. G. Shaltyiauser 710 on the $500 short-wave receiver contest MANUSCRIPTSare piling into the office, and those who have not yet What Our Readers Write Us 716 become actively interested in the problem should turn at once to page 657 and set their brains to work. W. K. W. 0*= & Co. Page & Co. Doubleday, Page Doubleday, Doubleday, Page & Co. Doubleday, Page Sr Co, MAGAZINES BOOK SHOPS LORD & TAYLOR BOOK SHOP OFFICES OFFICERS COUNTRY LIFE PENNSYLVANIA TERMINAL (2 Shops) GARDEN N. Y. NEW YORK: CITY, F. N. President WORLD'S WORK WALL ST. AND I66WEST 32NDST. DOUBLEDAY, BUILDER 38 NEW YORK: 285 MADISON AVENUE GARDEN & HOME GRAND CENTRAL TERMINAL A. W. PAGE, V ice-President RADIO BROADCAST BOSTON: TREMONT BUILDING c , I 223 NORTH STII STREET SHORT STORIES NELSON DOUBLEDAY, ^'ice-President I 4914 MARYLAND AVENUE CHICAGO: PEOPLES GAS BUILDING EDUCATIONAL REVIEW 20 GRAND AVENUE RUSSELL KANSASu'.v, . c CITY,r,. ) 9 SANTA CAL. DOUBLEDAY, Secretary LE PETIT JOURNAL SyREET BARBARA, j ^ WEST 4?TH EL Eco CLEVELAND' HIGBEE Co. LONDON: WM. HEINEMANN LTD. S. A. EVERITT, Treasurer FRONTIER THE SPRINGFIELD, MASS. MEEKINS, PACKARD^ WHEAT OXFORD UNIVERSITY PRESS Asst. Treasurer WEST TORONTO: JOHN J. HESSIAN, OOUBLEDAT, 'PAGE & COMPACT, Garden Qity, N.ew Copyright, 1926, in the United States, Newfoundland, Great Britain, Canada, and other countries by Doubleday, Page & Company. All rights reserved. TERMS: $4.00 a year; single copies 35 cents. 640 RADIO BROADCAST ADVERTISER 641 uson The Gold Standard fRadioReceivers THE "FORTY-NINERS" washed out for the A3 hidden particles of gold, so, today, the wise buyer sifting through a confusion of extravagant claims and choosing on perform- ance alone finds Ferguson, "The Gold Standard of Radio Receivers." Readily piercing through the maze of local broadcasters, the Ferguson unfailingly finds the more remote stations. Its three stages of Matched Audio give ample volume so that you may not only hear but enjoy their programs. Its life-like reproduction is true as gold. One Tuning Control Arrange with the nearest Authorized Calibrated in Meters.' Ferguson Dealer for a demonstration in own or write us. Select your program, your home, turn up its wavelength and in comes your station. In accomplish- J. B. FERGUSON, Inc. this feat in radio ing 41 East 42d Street design, there has not been the slightest NEW YORK, N. Y. sacrifice in electrical ef- ficiency. The single tuning knob revolves the shaft by all means of a split gear that eliminates back- lash. A pivot bearing gives this control its velvet- smooth ease. The Receiver is mounted upon a rigid aluminum chassis. CABINET MODEL EIGHT A Six-tube Tuned r. f. Receiver, $226 Tested and approved bv RADIO BROADCAST * American Museum of Natural History and Asia LISTENING-IN AT PEKIN most of the natives here were so for Although radio broadcasting has already made its debut in some Chinese centers, listening-in doing was sent to the the first time. The sets are those of the scientific expedition headed by Roy Chapman Andrews, which Mongolia through and Asia The shows one of the expedition cooperative efforts of the American Museum of Natural History, magazine. upper picture retainers are to a from Tientsin in the lower picture mystified by the voice in the box, while the other shown listening program RADIO BROADCAST VOLUME VIII NUMBER 6 APRIL, 1926 The Period 1872 to 1897 Hughes, Dolbear, Hertz, Branley, Lodge, Tesla, Popoff Marconi's Early Life Wireless is First Put on a Commercial Basis By ROBERT H. MARRIOTT First President, Institute ofRadio Engineers CHAPTER I of "How Radio Grew coherer method of reception and went back his invention as a mode of electric com- Up" we rapidly traced the growth of to the telephone and detector method. munication, and said in the description, radio science from its earliest stages Hughes made his demonstrations to "Communication may thus be established INfrom the time when Luigi Galvani con- fellow scientists who appeared to be bent between points certainly more than half ducted his researches in 1790, probably on discouraging him, and years later he a mile apart; but how much farther I cannot " knowing little about what he was actually said, I was so discouraged at being unable now say." doing, through the researches of De Salva, to convince them of the truth of these It looks now as though both Hughes's and of Morse, and of Maxwell. The electro- aerial electric waves that I actually re- Dolbear's devices were pretty fair radio magnetic induction experiments of Faraday fused to write a paper on the subject ." devices for that time; but apparently those were also described, and the story concluded In 1882, Professor A. E. Dolbear, of equipments were not deliberately designed with one Loomis, who, in 1872, took out a Tufts College, built a transmitter and a and operated on the basis of the now patent for a special apparatus designed to receiver, with antenna and ground, that accepted electro-magnetic wave theory of utilize electricity collected from the atmos- apparently must have operated according Maxwell.