On the Cover “Life tests on continous evacuation of 304TL / March 8, 1943” Shows impromptu test rig at Eimac’s Salt Lake City plant. Subject: 304TL triode is at upper center of photo, attached to a vacuum manifold atop an oil diffusion pump. An ion-guage tube is on the same manifold, to the left. A...
On the Cover The “Liberty Valve” as once sold by the Radio Apparatus Co. of Pottstown, Pa In this issue
On the Cover A pre-prototype leading to the Eimac 304T, from an affidavit filed by Ronald H. Gordon, laboratory glassblower. He certified having made the tube “before1940.” The objective was to contest, successfully, a claim of inventing a “plurality of grids in an envelope” in a patent application by Harold Zahl of the Signal Corps....
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 base-branding machine in the De Forest Radio Co. plant, ca. 1929. The five-pin basses rotate into contact with the branding die – the white object at lower center above the pipe elbow. Heated by a gas flame just below, it burns the De Forest script logo into the base. In this...
The Western Electric 7C22, a packaged push-pull radar oscilator. See story on p. 16 In this issue
Daniel Stocks, Australian microwave-tube expert, left visits Ron Lawrence and his “Radio Heaven” display in North Carolina. Photo: Robert Lozier. In this issue
On the Cover The Eimac X272 developmental tetrode from 1944 – a 4-125A with three radial pins added to reduce lead inductance. In this issue