Radio broadcast .. (1922-30)

RADIO BROADCAST ADVERTISER 395 pad, you would not find either device even mentioned. The author makes no bones about this. "As in the previous edition," he writes in the new preface, "no pretense is made that the book is a treatise on radio practice; in general, only the principles involved in the operation of radio apparatus have received attention. What- ever radio apparatus is discussed is dealt with only to illustrate those principles the text is in- tended to elucidate." But those principles, by diagram, mathematical and physical analysis, oscillogram, and every other resource of tech- nical instruction, it does clarify. The chapter on vacuum tubes alone runs to 240 pages, a book in itself, and after you have mastered it you know something about tubes. You may burn out the next one you put into a socket anyway, but at least you will not concoct any idiotic theories about it. If you believe that there is a dividing line between principles and practice, and that life is too short to include both, you will, of course, find no use for such a course as Morecroft offers. You had best go out and sell bonds, in that case. But if you are a radio engineer, or want to become one in the only genuine sense of the word, then Morecroft's textbook will be worth more than $7.50 to you. In a work of this size there are inevitably sections over which other engineers may disagree with the author. The treatment of " Elimination of Strays," pages 340-343, may be cited. In Fig. 16, "one of the early attempts to eliminate 'strays,'" ascribed to De Groot, is shown. This scheme is a neutralization system—one antenna tuned to the desired signal, the other aperiodic, etc. It will not work, which Professor Morecroft knows as well as anyone, but he does not tell the reader that the scheme is worthless, and why. The ingenious and useful wave antenna of Beverage, Rice, and Kellogg, which deserves mention in this section if anything does, is omitted without a word. Roy A. Weagant's name is twice misspelled. But such defects, which might be serious in a lesser work, are overshadowed by the high virtues of Morecroft's imposing con- tribution to radio science. CARL DREHER. USE THIS COUPON FOR KITS RADIO BROADCAST SERVICE DEPARTMENT Garden City, New York. Please send me information about the following kits in- dicated by number: Name... Address (Number) (Street) (City) (State) ORDER BY NUMBER ONLY. This coupon must accompany each order. RB 3-28 USE THIS COUPON FOR COMPLETE SETS RADIO BROADCAST SERVICE DEPARTMENT RADIO BROADCAST, Garden City, New York. Please send me information about the following manu- factured receivers indicated by number; Name... Address (Number) (Street) (City) (Stale) ORDER BY NUMBER ONLY This coupon must accompany each order. RB 3-28 A. C. OPERATION Type 440-A Transformer Price J10.00 The Type 44O-A Transformer illustrated is designed for use on 105-125 V (50-60 cycle) A. C. and is rated at 65 watts. The following voltages and currents are available. 2 Volts 10 Amperes 3-5 " 5 " S " 2-5 " 7-5 " 2 " The use of this transformer together with the new A. C. tubes and a dependable plate supply unit such as the General Radio type 445 Plate Supply and grid Bias unit makes the conversion of a battery operated receiver into one operated from the light socket very simple. If you do not care to undertake this change yourself go to your community set builder. He is well qualified to serve you. GENERAL RADIO Co. Manufacturers of Radio and Electrical Laboratory Apparatus 30 STATE STREET CAMBRIDGE, MASS. HEATER TYPE STANDARD SOCKET A-C Reception Can Be Yours A COMPLETE change to A-C power will make your set apparently 100 per cent more pow- erful. Be up to date—enjoy full, rich, clear toned reception brought in by Sovereign A-C Tubes. Only simple changes required in your set. Free yourself of all bother and cost of "A" Batteries — "A" Battery Eliminators — with Sovereign A-C Tubes on the job. Just plug into any light socket. No hum. No noises or microphonics. Tubes will not paralyze when collage changes. A treatise on A-C reception is yours for the asking. Write for copy. Sovereign Electric & Mfg. Co. 127 N. Sangamon St., Chicago, III. RADIO DEALERS Send for our catalog illustrating the prod- ucts of over 100 radio manufacturers. WHOLESALE ONLY! F. D. PITTS COMPANY 219-223 Columbus Ave. BOSTON, MASS., U. S. A. Established 1919