Radio Broadcast (May 1929-Apr 1930)

The principal technical features to be found in our receivers are a.c. screen-grid tubes for increased distance and stability, band-selector tuning for improved selectivity and the diminution of sideband cutting, a.c. screen-grid power detector for increased power output and improved fidelity, push-pull power output stage with new 245-type tubes to provide ample undistorted output, dynamic loud speaker of unproved high-frequency response, elimination of usual antenna installation which is replaced by a small antenna contained in the console housing the set and loud speaker, and automatic regulation of fluctuating power fine voltages. In S-M receivers will be found an "overtone switch," which cuts down the response to high tones at will. Two models are available, one a lowboy, at §169.00 list, and the second a highboy with sliding doors, at $195.00 fist. Both are of simple, semiSheraton design. Striped walnut, finished in gloss lacquer, is used in both models. STROMBERG-CARLSON TELEPHONE MANUFACTURING COMPANY Ray M anson, Vice President and Chief Engineer: Trends in radio receiver con struction point to detailed improvements only, and not to any radical changes in fundamental design. The worth-while trends center around improvements that make for better reproduction, as prospective purchasers of new radio receivers now realize that in the last analysis, the only object in owning a radio receiver is to obtain accurate and natural reproduction of what is going on before a distant microphone. One of the means for obtaining improved reproduction is the use of the new uy-224 a.c. screen-grid tube and the new ux-245 power tube. Three of these new a.c. screen-grid tubes used with four tuning stages increase the amplification possible up to the detector circuit, allowing for improved detector action, such as linear power detection with automatic grid bias. This year there are four new Stromberg-Carlson receivers, each of which makes use of three of the new a.c. screen-grid tubes. All of these models use the new linear power detection with automatic grid bias, working directly into a power output system employing the new ux-245 tubes. VICTOR TALKING MACHINE COMPANY H. C. Grubbs, Vice President: Victor has waited until 1929 to introduce its own radio receiver because we desired to give the public an instrument which would be as close to perfection as engineering ability could devise. Victor Radio and Radio with Electrola is unique in design, appearance, and performance. It is not an assembled set in any respect. A cabinet of exceptional beauty is made of rich walnut veneer. The receiver is a power-operated, completely shielded, tuse(] radio frequency set of the antenna type, utilizing ten Ray H. Manson, chief engineer, Stromberg-Carlson . C. Gmbb den t vice presi Victor. tubes. A mechanical system of micrometer adjustment, which we call "Micro-Synchronism," is employed and this feature permits a precision alignment of the chassis and a high degree of sensitivity and selectivity. Tuning is accomplished with a super-automatic device operating over a full-vision illuminated dial calibrated in kilocycles. The power amplifier employs a balanced push-pull circuit with two 245-type tubes. There is a harmonic modulator which allows the owner to get more or less emphasis on bass notes as he prefers. The dynamic loud speaker is of greatly improved design. The combination radio-instrument is equipped with an improved Electrola, induction disc motor, 12-inch turntable, and a newly designed electric pick-up unit. Victor Radio is very easy to service ; it is made up of four individual units any one of which may be disconnected instantly. THE ZENITH RADIO CORPORATION Thomas H. Endicott, Zenith Radio Corporation: The introduction of the new Zenith models which will make their appearance at the Chicago trade show will feature, foremost, the popularizing in the price of several Zenith receivers. This is made possible because of the increased manufacturing faculties brought about by the overwhelming demand of the public for high-grade radio receivers. The Zenith Corporation now makes all of the parts and also the cabinets used for their receivers. Our new cabinet plant is equipped with especially designed automatic machinery of entirely different construction from the type used in the average furniture factory. The newest design in screen-grid tube circuits will be incorporated in all of the new models for 1929-1930. Improved "Automatic Tuning," will also be found on all models. COLUMBIA PHONOGRAPH CO., INC. Harry A. Summers, Research Division : The trend in radio receivers for the 1929-30 season is in the direction of reduction of cost by means of simplification as far as it may be carried without sacrifice of performance. Coupled with this is a reduction in the number of tubes used, which gives simplicity in service and manufacture, resulting in lower cost on both these items. Our receivers for 1929 respond to these trends, being moderately priced and highly compact. These sets employ 327-type tubes in all sockets except the power stage which uses two 345-type tubes in push pull. In this way we obtain a power output equal to a pair of 210 tubes without the use of high voltages and with resulting economy of parts. The new dynamic loud speakers which we use in these sets do not over accentuate the low frequencies and high frequencies are reproduced at more nearly normal levels. This has been accomplished by redesigning the motor and by the use of a Burtex diaphragm. Thomas II. Endicott, Zenith Radio Corp. 7 6 • • JUNE • 1929