Radio broadcast .. (1922-30)

RADIO BROADCAST APRIL, 1928 WILLIS KINGSLEY WING, Editor KEITH HENNEY EDGAR H. FELIX Director of the Laboratory . Contributing Editor Vol. XII, No. 6 <» No. 177. Characteristics of Speech No. 178. The Exponential Horn No. 179. A Problem in Audio Amplification No. 180. B Power Unit Characteristics No. 181. R. F. vs. A. F. Amplification No. i8». Filter Condensers No. 183. The Type 280 and »8i Tube* No. 184. Tuning 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. . . THE issue before you contains a variety of articles appealing to all tastes. For the short-wave enthusiast there is the constructional article on the code and telephone transmitter on page 410. For experimentes, we offer many articles, such as those on a two-tube, screen-grid receiver, measurements on the "Lab" circuit receiver, the circuit and description of a non- motor-boating resistance amplifier, the technical editorials, "Strays from the Laboratory," descriptions of tests on B- power units for hum characteristics, how to operate the Ham- marlund-Roberts "Hi-Q" set on a.c., and the story on how to convert many standard receivers for a.c. operation. Of more general interest, there are the reviews of new phonograph records. "The Listeners' Point of View," the editorial section, "The March-of Radio," the invaluable "As the Broadcaster Sees It," the article by Sylvan Harris describing modern me- thods of phonograph record making, and many others. /'"AWING to causes which were beyond our control, we are \^J unable at the last moment to present the article on a new tube for B-supply units, promised in the announcement on our cover. This article will appear as soon as it is finally released by the manufacturer. THE May RADIO BROADCAST will be full of features which will make it one of the most important issues we have had in many months. Lloyd T. Goldsmith of M. I. T. has writ- ten a description of a short-wave receiver, and an intermediate- frequency amplifier using the screen-grid tube. This receiver, especially when used for code reception, provides efficiency heretofore impossible before the advent of the screen-grid tube. There will also appear in the May issue a most accurate list of international short-wave stations. Many readers have asked for a description of a power supply circuit for use in direct- current districts and an article describing a practical circuit for this purpose will appear in May. THE problems of synchronizing broadcasting stations and, in general, of accurate frequency control for radio sta- tions, has assumed great importance in the past year. Edgar H. Felix has prepared an accurate report of what has been ac- complished to date and an analysis of the immediate possibilities in an interesting article scheduled for the May number. For radio constructors, Hugh S. Knowles is writing a description of an a.c. operated "Lab" circuit receiver which has many interesting features, besides its efficiency and flexibility of use, to commend it. This story is also scheduled for May. CEVERAL additional regular features are being planned •^ for the coming numbers of RADIO BROADCAST and it is hoped to start the first of them with the May issue. Each of these features will appeal in a very practical way to a large number of the radio fraternity. . . . Those interested in infor- mation about the Cooley Rayfoto system of picture reception who desire to be placed in touch with the manufacturers may address their letters to the undersigned who will forward them. — WILLIS KINGSLEY WING. DOUBLEDAT, OORAJi & COMPACT, IXC., Garden Qity, New Tor\ MAGAZINES COUNTRY LIFE WORLD'S WORK GARDEN & HOME BUILDER RADIO BROADCAST SHORT STORIES EDUCATIONAL REVIEW LE PETIT JOURNAL EL Eco FRONTIER STORIES WF.ST THE AMERICAN SKETCH BOOK SHOPS (Books of all Publishers) I LORD & TAYLOR; JAMES McCREERY & COMPANY \ PENNSYLVANIA TERMINAL AND 166 WEST 32ND ST. NEW YORK: < 848 MADISON AVE. AND 51 EAST 44™ STREET j 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 SPRINOHELD, 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: OXFORD UNIVERSITY PRESS OFFICERS F. N. DOUBLEDAY, Chairman of the Board NELSON DOUBLEDAY, President (piuKt.i- H. DORAN, V ice-President S. A. EVERITT. Vice-President ki SM l.L DOUBLEDAY, Secretary JOHN J. HESSIAN, TREASURER 1.11 I.IAN A. COMSTOCK, Asst't Secretary L. J. McNAUGHToN, Asst't Treasurer Copjrighl, 1928, in the United Statei, Keivfoundland, Great Britain, Canada, and other countries by Doubleday, Dorai TERMS: $4.00 a year; single copies 55 cents. 400 • Company, Inc. All r.ghts reserved.