General Electric Radiator Tube (ca. early 1920s) |
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This is a fairly early version of a radiator tube that was produced by
General Electric. I am guessing that it dates from the early 1920s
because the patent dates on the cathode arm range from 1911
to 1919. There is no model number, but it does have "30 MA" etched
on the glass, i.e., it is rated at 30 milliamps.
The design characteristics that distinguish this tube from the later radiator tubes in the collection include its use of a focal cup (see photo to right), and the fact that the cathode has a 45 degree angle. The filament takes the form of a concentric spiral, just like that of the "Universal" tube, but the discoloration of the bulb makes it difficult to see. The anode employs a tungsten target embedded in a copper head.
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The deposition of tungsten on the inside of the tube envelope is so great that the glass on the cathode half of the bulb (the right side in the photo above right) has a mirror finish. This excessive deposition of tungsten indicates that the tube was operated beyond its rated capacity. The glass also has a radiation-induced purple color to it. Size: ca. 14 1/2" long (excluding rod for radiator fins), 3 3/4" bulb diameter Donated by the University of Kansas courtesy of Michael Lemon |
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