On the Covers Two halves of a composite four-tube photo, from the De Forest Radio Co. A 10-1/2 X 19-1/2 print of this image turned up in the recent Boyer Estate auction conducted by the CC-AWA group. This is quasi-historic stuff: spired article in Raadio News, May, 1930. In this issue
On the Cover A reproduction of De Forest catalog art: images of the 500 and 504A triodes. The artist’s originals can be yours, via the CC-AWA auction planned for March. See p. 1 for details. In this issue
On the Cover The Eimac X-4 developmental triode of June, 1942; one of many versions that finally led to the 527 radar tube. The anode is from the 250T. Filament drain is 7.5v@30A. In this issue
On the Cover A Western Electric 240A with the radiator and anode cut away to show internal construction. Note that the water inlet and oulet fittings are displaced from each other, presumably to induce a spiral flow of the colling water. Photo from the late Bell Labs Historical Museum. In this issue
On the Cover The Eimac X-O from early 1942, first of a numbered line of “X” developmenta types that eventually ran into the low thousands, and one of the umpteen possibilities that eventually yielded the 527 radar triode. It appears to use th eduel stacked anode assembly and grids from the VT-158 Zahl tube, in...
On the Cover A bit of De Forest Radio Co. art from ca. 1931. It appears to be allegorical: the young Lee De Forest, being inspired to invent his Flame Audion, and the resulting, perfected S-bulbed triode. Of course, this month marks the 100th anniversary of successful tests of the first vacuum audions. In this...
On the Cover This appears to be British Post Office “Valve Amplifing No. 1,” made by BTH, as discussed in Keith Thrower’s British Radio Valves – The Vintage Years; 1904-1925. The photo is of a sample in the long-abolished tube museum at Bell Laboratories. Photo: Bell Labs, courtesy of Jerry Vanicek. In this issue
Removing sealed-off tubes from a small Sealex machine at the De Forest Radio Co. plant in Passaic, NJ, about 1931. In this issue
On the Cover One version of the George Clark receiving tube, Fig. 1 of Bill Condon’s article that starts on Page 2. In this issue
Lee De Forest jollies-up with Roy Weagant, namesake of a family of external-controlled tubes of ca. 1919. The picture was taken in the officees of Sheffield and Betts, patent attorneys in New York. The origianal caption was “When Grid and Gridless Meet. Phot: Jerry Vanicek. In this issue