The “Pedoscope” Coolidge Tube
Dating probably to the thirties, this
Coolidge type line focus tube is 10” (25cms) long with a 4” (10cms) bulb. It
is fitted externally with a black-painted spool-like aluminium heat sink
fixed on the protruding anode shaft. A voltage adjusting rheostat is visible
on the cathode end of the tube, fitted to the two-prong connection of the
filament. Note the
slightly conical shape of the copper anode, and the unusual 30 degree angle
of the target surface. This angle falls half way between the 45 degree target angle in gas discharge tubes and in
early Coolidge type tubes, and the usually low, 10-15 degree angle, in the line focus tubes introduced in the Twenties. This tube bears an etching “Made in It comes most probably from the English
made “Pedoscope” shoe-fitting fluoroscopy device. Such devices came in use in
the twenties, and were still in frequent use in the fifties. But, owing to
the high risk of radiation, they were gradually banned in the sixties, and
practically disappeared in the early seventies. The “PEDOSCOPE” ( |
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