Radio broadcast .. (1922-30)

RADIO BROADCAST OCTOBER, 1928 WILLIS KINGSLEY WING, Editor KEITH HENNEY EDGAR H. FELIX Director of the Laboratory Contributing Editor Vol. XIII. No. 6 Cover Design - - - From a Design by Harvey Hoptyns Dunn Frontispiece Where Radio Progress Begins 330 Television—Its Progress To-day - - - - Howard E. Rhodes 331 A Nine-Tube Screen-Grid Super - Robert Burnham 334 The March of Radio An Editorial Interpretation 337 The Low-Power Stations Plead Their Case Here and There Regulations for Television and Picture Trans- mission The "Hi-Q 29"—A Receiver with a Band-pass R.F. Amplifier D. K. Oram 341 A Short-Wave Transmitter for 1929 - Robert S. Kruse 344 "Strays" from the Laboratory - - Keith Henney 347 Two Interesting Patents Engineers as Salesmen Radio as a Scapegoat Testing for Soft Tubes A Screen-Grid Mystery Short-Wave Reception Mortality Among the A.C. Tubes The Remler A.F. Amplifying System A Two-Tube A.C. Screen-Grid Tuner - James Millen 349 As the Broadcaster Sees It - - Carl Dreher 352 Sound Motion Pictures Lord Rayleigh on Sound The Sargent-Rayment Seven Receiver - - - Howard Barclay 354 "Radio Broadcast's" Home Study Sheets ••«•>» , , , j^^ Nos. 7 and 8. Alternating Current The 222 Tube as an R.F. Amplifier (Part II) Glenn H. Browning 359 Book Review Carl Dreher 360 Coupling Methods for the R.F. Amplifier - Bert £. Smith 361 "Our Readers Suggest—" - - - . , . , jg 4 A Power Unit Voltage Divider Dynamic Speaker Field Supplied from B-Power Obtaining Screen-Grid Bias Unit Testing for Soft Tubes A Simple Audio Channel Equalizer Matching Condensers and Coils in Tandem A.C. Tube to Reduce Microphonics Tuned Circuits An Antenna Booster for Loop An Amplifier Kink An Output Filter Without a Condenser The "Vivetone 29" Receiver R. F. Goodwin 366 "Radio Broadcast's" Service Data Sheets on Manufactured Receivers - ,,,, jg^ No. 9. The Bosch Model 28 Receiver No. m. The Splitdorf "Inherently Electric" Receiver Practical 5-Meter Hints - - Robert S. Kruse 371 New Apparatus - - - Useful Information on J^ew Products 372 Radio Helps in the Coast Survey - - - D. L. Par^hurst 374 Manufacturers' Booklets 376 "Radio Broadcast's" Laboratory Information Sheets 378 No. 225. Calculating Grid Bias for A. C.Tubes No. 220. The Telephone Transmission Unit No. 126. Grid Bias Circuits for A.C. Tubes No. 130. Filters No. 227. The Audio Transformer No. 23 1. Impedance-Coupled Amplifiers No. 208. The Dynamic Loud Speaker No. 132. The Voltmeter Photo Broadcasting in England - - - William J. Brittain 384 Letters from Readers - 386 The contents of this magazine is indexed in The Readers' Guide to Periodical Literature, which is on file at all public libraries. AMONG OTHER THINGS. . . READERS who did not see our announcement in this space last month with respect to the change in our publication date and who failed to see our October issue when they ex- pected may be somewhat confused. Effective with this number, RADIO BROADCAST is on sale at all good newsstands on the first of the month. That is easy enough to remember. THE issue before you now contains an unusually wide range of material, and in the descriptions of receivers offered the constructor in kit form for the present season, is especially complete. Our November issue promises a story on present trends in radio progress, a description of a new audio amplifier system, two articles on television, the first of a series of practical articles on radio service for men actually facing the music, and a variety of constructional articles. These are in addition to our popular departments which will run as usual. A FEW of our readers who carefully classify the contents of each issue feel that each article should be classified according to the Dewey decimal system when published. At one time our excellent British contemporary, Experimental Wireless, classified their articles this way, but has since discon- tinued the practice. RADIO BROADCAST is quite willing to serve its readers, but we feel that this classification would appeal to all too few. The editor would be glad to hear from those who favor the scheme—and from those who prefer the status quo. AND here we group many miscellaneous matters; read them, but remember, you were warned!... The complete set of "R. B. Lab. Data Sheets" in book form—No. 1-190— is now available at $i per copy from the Circulation Depart- ment of this company. . . . We shall soon start a special depart- ment, along lines similar to "Our Readers Suggest—" to be made up of practical contributions from radio service men and professional set builders. Quite a few interesting contributions are already in the office and readers who desire to submit any ideas that seems to them worth while passing on are invited to do so. The same general rules hold for these contributions as for the "Readers Suggest" department. . . . How many readers are interested in the problems of series-filament connection for a.c. operation? We should like to hear from readers who have done some work along this line, or from those who would like an article devoted to the subject. ... In the past few weeks, our mail has contained a number of simple questions about radio which we are thinking of answering in a short article composed simply of the questions and their answers. We invite the sub- mission of short and particularly troublesome questions which readers would like to see treated in this way. ... A radio house in Sao Paulo, Brazil, informs us that they are expanding and desire exclusive American agencies for radio apparatus in Brazil. Manufacturers who wish to get in touch with this house may write the editor. . . . Our request in the August "Strays" for methods of testing for hard and soft tubes has brought two answers. One may be found in this number on page 348, in the "Strays" department, and the other on page 364 in the depart- ment "Our Readers Suggest—' ' I 'WO of the writers in this issue who have investigated the JL use of the screen-grid tube with various kinds of coils, arrive at conclusions which are different—but most interesting. The stories concerned are by Bert Smith and Glenn Browning. — WILLIS KINGSLEY WING. OOUBLEDAT, & COMPACT, I^Q, Garden Qity, ^.ew MAGAZINES COUNTRY LIFE WORLD'S WORK THE AMERICAN HOME RADIO BROADCAST SHORT STORIES EDUCATIONAL REVIEW LE PETIT JOURNAL EL Eco FRONTIER STORIES WEST THE AMERICAN SKETCH BOOK SHOPS (Books of all Publishers) t LORD & TAYLOR; JAMES McCREERY & COMPANY \ PENNSYLVANIA TERMINAL AND 166 WEST 32ND ST. NEW YORK:< 848 MADISON AVE. AND 51 EAST 44TH STREET I 420 AND 526 AND 819 LEXINGTON AVENUE * GRAND CENTRAL TERMINAL AND 38 WALL STREET CHICAGO: 75 EAST ADAMS STREET ST. Louis: 223 N. STH 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. OFFICERS F. N. DOUBLEDAY, Chairman of the Boar . NELSON DOUBLEDAY, President GEORGE H. DORAN, Vice-President S. A. EVERITT, rice-President RUSSELL DOUBLEDAY, Secretary JOHN J. HESSIAN, Treasurer LILLIAN A. COMSTOCK, Asst't Secretary Copyright, 1928, in the United States, Newfoundland, Great Britain, Canada, and other countries by Doubkday, Doran TERMS: $4.00 a year; single copies 35 cents. 328 TORONTO: DOUBLEDAY, DORAN & GUNDY, LTD. L. J. MCNAUGHTON, Assft Treasurer Company, Inc. All rights reserved.