General Electric KR-3 Kenotron Tube (ca. 1930s) |
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Quoting Grigg's Trail of the Invisible Light: "In 1914, at GE's
Research Lab in Schenectady, [Saul] Dushman developed the hot cathode valve
tube. This [referring to a photo of the KR-3] is the first commercial model
(KR-3). Its long life stemmed, in part, from the fact that the anode
surrounded the cathode, thus preventing erratic voltage drops from charges
developed on the inner surface of the glass."
The label on the stem identifies it as a "Coolidge" tube, but it came to be known as a "kenotron." Size: 20" long, 5" in diameter (bulb) The photo to the right show the spiral cathode inside the tubular, open-ended anode. |
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| The KR-3 was air cooled
(the KR-4 was oil cooled). References E.R.N. Grigg. Trail of the Invisible Light. Charles C Thomas. 1965. General Electric X-ray Corporation. Coolidge X-ray Tubes - Kenotrons. Bulletin No. 293. 1934. Donated by the University of Kansas courtesy of Michael Lemon |
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