Amperex Models 100NB and 200NB End Window GM Tubes (ca. 1960s)

There is nothing particularly unique about these end window GM tubes manufactured by Amperex Electronic Corporation. These particular examples probably date from the 1960s (most likely, the serial number 67-32 refers to 1967), but to look at them, they could just as easily have been manufactured yesterday. 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.

Amperex 100NB 200NB End Window GM Detector
Amperex 100NB 200NB End Window GM Detector

Size: 4.344” long and 1.375” diameter

Window: 1.093" effective diameter

  • Model 100 NB 3-4 mg/cm² (beta, gamma)
  • Model 200 NB 1.4-2.0 mg/cm² (alpha, beta, gamma)

Operating voltage: 900 volts

Dead time: ca. 200 usec

Cathode: Plastic coated stainless steel

Gas: Neon, halogen quenched

Base: Four prong

Donated by Ron Kathren.


  • Ron Kathren personal communication.
  • Amperex Nuclear Products catalog of radiation tubes, 1981.