Category: Magazines

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...

Front Cover, Rear Cover Upper, & Rear Cover Lower Just Qvistad, LA9DL, and part of his tube collection. Various European receiving Tubes. The front row has the Lorenz DF41W at left, and a group of rare RFT (East German) miniature “gnome” types: EAA171, UCH171, UB171, etc. Rear row: three Loewe multi-unit tubes at left, two...

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

On the Cover The 6324 commutator tube. See page 3. In this issue

The rare and prestigious Western Electric/Signal Corps VT-3. Photo by Bill Condo The rare and prestigious Western Electric/Signal Corps VT-3. Photo by Bill Condon In this issue