Radio Broadcast (May-Oct 1924)

The March of Radio paratus at the two ends of the wire (or radio channel) stay in synchronism, and if no interfering currents step in to blur the picture, the reproduction is really quite truthful, and a reasonable reward for the great efforts which have been expended on this problem. Transmission by wires, it seems, is somewhat more reliable than by radio as the disturbing currents can be better controlled. The Matin seems overenthusiastic about this scheme of Belin; its editor at once jumps to the conclusion that teleview, or long distance seeing, will soon be accomplished. To those who know how the picture transmission is carried out, however, long distance seeing is still far from a solution and apparently not to be attained by the methods at present used, if at all. " Building Your Own" Requires Care 4T THE request of one of our friends we L \ throw out a word of caution to those 1 V radio enthusiasts who spend most of the time formerly devoted to the theatre, cards, and billiards in dabbling with radio apparatus. It is really very instructive and satisfying to build a good radio set and the fewer the parts bought "ready made" the greater is the satisfaction — if it works. There are radio experimenters who want a "push -pull" amplifier to operate their loud speaker. This unit requires special transformers. These special transformers are not legitimately on the' market, we are informed, as they apparently infringe patent rights of the American Telephone & Telegraph Co. You can buy them from the company— providing you buy the rest of the amplifier unit. As the transformers are practically the whole thing in the amplifier it is quite in line for the enthusiast to try and wind his own. So this experimenter with another devotee, decided to build his own push-pull transformers and thereby acquired experience — of a sort. To wind a suitable transformer it is advisable to use wire insulated with enamel only. Silk or cotton insulation takes up so much room in these small sizes of wire that a compact transformer with silk insulated wire is impossible. Many thousands of turns are required on a transformer. After calculating the design of the transformer in the proper way, they wound them, using up several afternoons which, it turned out afterward, might have been spent on the golf links to much better advantage. For after finishing the tedious winding job, the transformer wouldn't work. Tests showed that many turns were short-circuited — evidently due to weak spots in the enamel insulation and somewhat careless winding. If, during the winding operation, one turn of such a transformer is pulled so tightly that it imbeds itself deeply in the winding already on the core, a short circuit is probable. And so we received the suggestion, "Tell your readers of my experience. They had better make layer-wound coils if they are going to wind thousands of turns of small enamel covered wire." WGY Finishes Its Dramatic Season T HE Schenectady station of the General Electric Co. can well claim the distinction of being the pioneer among dramatic broadcasters. This type of radio % ^ ■ CARL W. MITMAN Curator of Engineering, of the National Museum at Washington, holding what is believed to be the first radio tube. It was made in 1898 by D. McFarlan Moore of New York. Waves from this tube were used to blow up a miniature of the battleship Maine