Raytheon Model CK 1020 and 1021 GM Tubes  (ca. early 1950s)

The Models CK 1020 and 1021 are nearly identical thin wall beta-gamma GM tubes manufactured by Raytheon Manufacturing Company of Newton Massachusetts. The only difference between the two is size: the 1020 is 3/4" longer than the 1021. In the photo, the tubes on the left and in the center are Model 1020s. The tube on the right is a 1021. Because the tubes are light sensitive, they are painted black.  For fun, I removed the paint from the top end of the tube in the center of the photograph.  As such, the end of the cathode, a thin coating of aquadag on the inside of the glass, is visible. 

Size:  CK 1020  6" long,  3/4" diameter

          CK 1021  5 1/4" long,  21/32" diameter

Wall: glass, 35 mg/cm2

Cathode: Inner surface of glass wall coated with aquadag (3" for 1020 and 2.5" for 1021) 

Operating voltage:  850 - 950 volts

Gas: organic quenched



AEC Radiation Instrument Catalog, page date July 1, 1950

Nucleonics May 1949, page 96.

Nucleonics April 1954, back cover.

Raytheon technical specifications sheet. 



Donated by Ron Kathren

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Last updated: 07/25/07
Copyright 1999, Oak Ridge Associated Universities