Amperex Model 90NB GM Tube (1950s)
The Model 90 NB cylindrical (side window) GM tube was manufactured by the Amperex Electronic Corporation of Brooklyn, New York. Like many thin walled GM tubes, the Model 90 NB is ribbed for additional strength. Its main use would be in survey instruments.
I believe that the N in the model number refers to the use of a neon fill gas and that the B refers to the four pin base.
Size: 5.625" long and 0.625" in diameter
Cathode wall: Stainless steel, 30 to 40 mg/cm²
Dead time: ca. 100 usec.
Gas: Neon, halogen quenched
Operating voltage: 900 volts
- Atomic Energy Commission Radiation Instrument Catalog No. 2. Part 1, 1950. Page BG-2B10A.
- Atomic Energy Commission Radiation Instrument Catalog No. 3, 1952. Page BG-2B10A.
- Amperex Nuclear Products catalog of radiation tubes. 1981.