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 Some “unborn” Kellogg AC tubes. As Alan Douglass describes them: A Friend just presented me with a cigar box containing these four specimens, along with poop sheets for the McCullough and Kellogg tubes. Evidently someone toured the plant and fished souvenirs from the scrap barrel. These look earlier than any finished tubes...
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 Cover The Eitel-McCullough X-7 triode of mid-1942, one of many exploratory designs that eventually yielded the 527 radar tube. 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