Radio and Television Today (Jan-Nov 1941)

RADIO PARTS IN DEFENSE A powerful sound system has a loud voice in commissioning the U.S.S. Bristol at Brooklyn, N. Y. Atlas speakers (circled, upper right) were clearly heard by officers, crew, workers, etc. Speeding up of the National Defense Program has brought into use hundreds of applications of radio tubes and electronic devices. These are being multiplied under the whip of war preparation, on a scale never before achieved. And out of these applications are coming new developments which will eventually be used for future peace uses. From time to time, these Defense applications of radio and radio tubes are reviewed during the weekly "Radio Magic" periods on the NBC Blue network, which are conducted by Editor Caldwell of Radio Today. These programs originate in the studios of key station WJZ in Radio City, New York, at 7:15 EST (6:15 CST). Following are notes on Defense uses of radio tubes and photo-tubes, discussed during recent "Radio Magic" programs. PHOTO-TUBE MAKES STEEL Take the manufacturer of steel, most vital of defense materials. The phototube or electric-eye — which never suffers from squint, strain or hangover — is now bringing back to the hardpressed steel industry the famous Bessemer process, which was dropped at the turn of the century in favor of the Jobber on guard! Arthur L. Dunn of Radio Equipment Corp., Meissner distributor at Omaha, whose picture arrived too late to join group opposite. slower but more accurate open-hearth furnace. The Government recently asked steel companies to consider construction of Bessemer converters as a means of speeding up the manufacture of steel and as a result several are now being built. The Bessemer process is the fastest way to make steel. Also, it is the most spectacular, for roaring flames rise 30 feet in the air as it turns a melt of iron into steel. The Bessemer process was dropped years ago when the open-hearth method was found to give more accurate control. For the Bessemer's difficulty was the fact that its successful operation depended solely upon the skill of its human operator. This expert with a trained color sense — called the "blower"— controlled the flaming, blasting converter by sight, judging what to do by the color and appearance of the flame. But sometimes the "blower" would be suffering from a hangover, to the detriment of his eyesight and of the steel he was making. A little bleary, his eyes might not note a change of color at exactly the right moment — and away to the scrap heap would go a charge of steel. SPEEDS PRODUCTION. HARDENS STEEL Now, however, a photoelectric cell, which never has hangovers and never sleeps, can take over the duty of watching the "blow" and deciding when to increase or decrease it. And so for Defense, there are now made available the Bessemer converter's advantages, for it can make steel faster, it can make it entirely from pigiron — thus conserving inadequate stocks of scrap — and it can be used in a speed-up process known as duplexing. For the Bessemer does its work in about half an hour, while the open hearth takes 12 to 18 hours to produce a heat. Meanwhile, the new Radio Magic process of surface hardening steel by means of induced radio waves, has made it possible to use relatively cheap and plentiful steel for shells, instead of special steel costing five times as much. The hardening process has thus expanded the available materials for shell production many fold. PE TUBE IN NIGHT SNAPSHOTS Another use of the photo cell is in taking night airplane pictures of enemy territory. This American method of photographing cities, dockyards and other strategic positions by night has recently been used with brilliant success by the Royal Air Force. With engines cut off, the reconnoitering plane drops to an altitude of a mile and releases a flash bomb containing from twenty to forty pounds of magnesium powder, which enormous amount is touched off by a time fuse. The momentary blinding glare causes a photoelectric cell to trip the shutter of a camera in the airplane on high. As each bomb is thus exploded a terrain of about five square miles is photographed. Also, the film is automatically shifted to bring a new frame in line after each flash. VIBRATION TESTS Radio tubes now also test basic raw materials such as steel. Every day in the testing laboratories of steel plants, turning out vast quantities of defense material, a continual fatigue-strength test of steel goes on. The Rayflex fatigue-testing machine meets industry's demand for the most scientific procedure to accurately conduct these tests. The Rayflex machine vibrates a specimen bar of steel by the means of electro-magnets actuated from an oscillator-amplifier combination with frequencies varying from 6,000 to 18,000 cycles, condensing all the wear of years into a matter of minutes! The control apparatus, which must not fail under the exacting conditions of these essential tests, uses standard radio tubes. The many instruments required on the control boards of modern airplanes, must be given severe vibration tests, to make sure they will stand up under the terrific vibration of planes in flight. Formerly the instruments were put on a motor-driven rattling table and given a good shaking. But this is (Continued on page 58) NOVEMBER, 7947 35