Radio Broadcast (May 1928-Apr 1929)

DEC 31 ffi6 RADIO BROADCAST JANUARY, 1929 Keith Henney Director of the Laboratory Willis Kingsley Wing, Editor Edgar H. Felix Contributing Editor Howard E. Rhodes Technical Editor Vol. XIV. No. 3 QOWEHTS Cover Design * ' ' From a Design by Harvey Hop\ins Dunn Frontispiece A Kite Antenna Used in Early Radio Experiments Unscrambling Television Boyd Phelps All About the Dynamic Loud Speaker ' Joseph Morgan Book Review Carl Dreher The March of Radio Wgy's Attack on the Allocation Plan Ira E. Robinson Stands Firm The Regenerative Decision ' An Editorial Interpretation With the Broadcasting Stations Commercial Radio Telegraphy With the Radio Manufacturer A Few Radio Questions Answered ' Measuring a Receiver's Performance "Strays" from the Laboratory ' How Much Power Is Needed? What is a Dynamic Speaker Some Interesting Formulas Obtaining C Bias The Task of Editing Empirical Rules and Formulas A Loop-Operated Browning'Drake Receiver ' /. H. Goc\el A Simple A.C. Operated Tube Tester ' The Laboratory Staff The Isotone Screen-Grid "Super" Dudley Walford "Radio Broadcast's" Service Data Sheets No. 15. The Bremer-Tully 8-20 Receiver No. 16. The Freshman Model Q Receiver Servicing Home-Made Radio Receivers B. B. Alcorn The Service Man's Corner Sound Motion Pictures ........ Carl Dreher "Radio Broadcast's" Home Study Sheets No. i}. Calibrating a Radio Wavemeter No. 14. Plotting Power Tube Characteristics As the Broadcaster Sees It Carl Dreher An Inexpensive Audio Oscillator Edward Stan\o A Chart for Making DX Measurements Armchair Chats on Short-Wave Subjects "Our Readers Suggest — -" New Apparatus and Its Applications More Data on the Sargent-Rayment Manufacturer's Booklets "Radio Broadcast's" Laboratory Information Sheets James B. Friauf Robert S. Kruse Howard Barclay No. 249. A Resistance-Coupled Amplifier No. 250. A Resistance-Coupled Amplifier No. 2?i. Moving-Coil Loud Speakers No. 252. Audio Amplifiers No. 253. Shielding No. 254. A.C. Tubes No. 255. Band-Pass Circuits No. 256. Power Output I56 157 159 l62 163 ' 166 Kenneth W. Jarvis 167 Keith Henney 169 171 173 174 177 179 181 182 183 185 186 188 189 192 194 197 199 202 The contents of this magazine is indexed in The Readers' Guide to Periodical Literature, which is on file at all public libraries. AMONG OTHER THIK[GS. . . THE next — the February — issue of Radio Broadcast will appear figuratively in new clothes. A famous designer is at work on an attractive new cover which will make Radio Broadcast more easily recognizable when you try to pick it out of the mass of others on the newsstands. The text will be set in a type which is easier to read and which presents a more attractive appearance than the type we now use. For those who are interested in such things, the present type face is Cadmus and the new Radio Broadcast will be set in Bodoni. Bodom is a decorative type also notable because it is "easy on the eyes." The contents is in for some improving at the same time and we shall ask you to await the February issue for a complete announcement of that. TELEVISION occupies a good part of radio discussion these days and we want to be sure that our attitude on the subject is clear. "Television," unfortunately,, means one thing to one man and something altogether different to the next. Television, like radio broadcasting, may be considered experimentally or in respect to its entertainment value — something the general public will find satisfactory. Television of entertainment value is certainly not here and is not in prospect for some little time. Articles in this magazine have outlined the difficulties to be overcome before "program television" can be attained. On the other hand, experimental television is here. What most people mean when they say the word now is merely experimental television. We do not intend to fill this magazine with articles on the subject when there isn't much to say, but we shall not fail to give those who are interested in experimenting with it as much useful information as we can. We certainly do not discourage experimenting, but in television it should be made perfectly clear that such it now is, and that on a limited scale. NO NEW feature we have added to Radio Broadcast in the six years of its history has created anything like the favorable response that the special pages for the radio service man have produced. Many interesting manuscripts have been received and we hope that others who also have ideas which should be set down on paper and sent on for our consideration will become suddenly ambitious and send us their contributions. THE present issue contains a wide selection of articles of interest: Boyd Phelps on "Unscrambling Television," Joseph Morgan on dynamic speakers, K. W. Jarvis on receiver performance, the Laboratory Staff on an a.c. operated tube tester, "The Service Man's Corner," Carl Dreher on "Sound Motion Pictures," and "Photographic Data for Broadcasters," Kruse on short-wave topics, the push-pull a.c. P. A. amplifier, are some of the most important. We are proud to offer these articles for they are all exclusive, interesting, and accurate to the last degree. FEBRUARY Radio Broadcast will contain, among other things, an article by Dr. L. M. Hull on "Overall Measurements on Broadcast Receivers," a striking story by Boyd Phelps on how amateur television has been accomplished, a remarkable story by the Labaratory on the value of filtering in audio amplifiers, several valuable experimental articles on short-wave work and — a host of other features. — Willis Kingsley Wing. VOU BLED AT, VORAK & QOMPAHT, INC., Garden Qity, Hew Tor\ MAGAZINES Country Life World's Work The American Home Radio Broadcast Short Stories Le Petit Journal El Eco Frontier Stories West The American Sketch BOOK SHOPS {Books of all Publishers) Lord & Taylor; James McCreery & Company Pennsylvania Terminal and 166 West 32ND St. New York:-^ 848 Madison Ave. and 51 East 44th Street 1 420 and 526 and 819 Lexington Avenue Grand Central Terminal and 38 Wall Street Chicago: 75 East Adams Street St. Louis: 223 N. 8th St. and 4914 Maryland Ave. Kansas City: 920 Grand Ave. and 206 West 47TH St. Cleveland: Higbee Company Springfield, Mass: Meekins, Packard & Wheat OFFICES Garden City, N. Y. New York: 244 Madison Avenue Boston: Park Square Building Chicago: Peoples Gas Building Santa Barbara, Cal. London: Wm. Heinemann, Ltd. Toronto: Doubleday. Doran & Gundy, Ltd. OFFICERS F. N. Doubleday, Chairman of the Board Nelson Doubleday, President George H. Doran, Vice-President S. A. Everitt, Vice-President Russell Doubleday, Secretary John J. Hessian, Treasurer Lillian A. Comstock, Asst't Secretary L. J. McNaughton, Asst't Treasurer Copyright, 1929, in the United States, Newfoundland, Great Britain, Canada, and other countries by Doubkdaj, Doran & Company Inc. All rights reserved. TERMS: $4.00 a year; single copief 35 cents. 154