Radio Broadcast (Nov. 1925-Apr 1926)

690 RADIO BROADCAST ADVERTISER tubes which are now available and which have been described in Radio Broadcast by Keith Henney. This voltage is then filtered by the necessary apparatus, so that what actually arrives at the plate of the power amplifier is clean, unvarying, noiseless power. The importance of high voltage in connection with faithful reproduction has been emphasized by Mr. George C. Crom of the American Transformer Company in the October, 1925, Radio Broadcast, and other points which are worthy of note will be published from time to time in a series of articles by engineers of the Raytheon company. They will acquaint the readers with the many interesting things that result from research in the Raytheon Laboratory, and it is believed that the intelligent application of the principles explained will result in many receivers in American homes that from the standpoint of beauty of reproduction will not be surpassed in the world. The principles upon which absolute fidelity of reproduction are founded have been explained many times in radio publications, and all that has been necessary has been the development of apparatus of the proper nature, and its distribution so that anyone could purchase and use it. The Raytheon tube in the few months it has been on the market has proved itself to be of the utmost importance in connection with power amplifiers and their necessary voltage supply. Because we are particularly careful concerning the dealers with whom we make arrangements to handle our tube, and the manufacturers of devices for use with it, and because we can honestly endorse the products of General R\dio Type 365 Rectifier Transformer Price #10 Type 366 Filter Choke Price #10 ■ * The popular topic of discussion among radio experimenters today is "B battery Elimination. ' ' Constant worry whether the "B's" are rundown — and their continual replacement will soon be a thing of the past in radio. A "B" eliminator never runs down and never has to be replaced. For a dependable plate supply unit which requires absolutely no attention other than its original installation, build a "B" eliminator of General Radio parts. Write today for full data on General Radio Rectifier Transformers and Filter Chokes, and get our circular with full instructions for building a Practical "B" Eliminator. Cambridge 39, Mass. It's a Beauty The Mayolian "B" Supply is encased in a beautiful mottled bluegray metal cabinet, 5 inches wide, 10 inches long, and q\ inches high, with a satin finish aluminum base and top, and engraved Bakelite panel. It harmonizes with any receiver and the furnishings of any room. Write for Complete Information MAYOLIAN RADIO CORPORATION, The "B" Without a Buzz Pioneers In Battery Elimination! The Mayolian "B" Supply assures to any radio set, regardless of make and under all conditions, a continuous, uninterrupted, noiseless, and uniform "B" supply direct from the light socket. Perhaps the most outstanding characteristic you will find in the trial tests of your Mayolian is that it improves the tonal quality of your receiver. This is obtained in the Mayolian "B" supply by the use of the Raytheon Rectifier plus three years of constant experimentation on the part of our own engineers. All voltages in the Mayo'.ian are variable because our engineers have found that variable voltage for the detector and radio frequency tubes is absolutely necessary to insure highest efficiency. The total amplification voltage is controlled by a three-way switch. By this means, you obtain the correct voltages, necessary to get the best results. It is possible to obtain with your Mayolian a high "B" voltage up to 180 volts. This produces great volume, sharp selectivity, and orthotone amplification. On second thought, it is but natural that the whole industry should look to Mayolian for a correct "B" Supply Unit for we are Pioneers in Battery Elimination.1* Write for complete information on the Mayolian Unit or complete list of Mayolian parts. This list of parts includes the Mayolian variable resistance for controlling detector and R. F. voltages. 1991 Broadway, New York City J V "A Better Condenser" See Page 715 of RADIO BROADCAST Advertiser, this number for official proof that the TOBE Condensers are the better condensers for use in the improved Raytheon Plate Supply Unit. Write us for full particulars and prices of separate condensers and of the new TOBE B BLOCK. To he D CORNHILL BOSTON, MASS. r RAYTHEON •fc Tested and approved by Radio Broadcast if