Nuclear Measurements Model GS-2 GM (ca. 1955-1960)
This is a Model GS-2 GM survey meter produced by Nuclear Measurements Corporation of Indianapolis, Indiana. they describe it as "A Value Packed Quality Instrument." The schematic located inside the case is that of the Model GS-3, but the number "3" has been crossed off and replaced with a "2". Unlike the Model GS-3, which employs an external probe, this unit has two GM tubes housed inside the case. Nevertheless, it does have a plug for an auxiliary external probe for drill hole exploration.
Detector: Two glass-walled GM tubes inside bottom of case
Range: 0-500, 0-5000 and 0-50,000 cpm
Dimensions (case): 3 1/4” x 7” x 3 1/4” excluding handle
Weight: 4 3/4 lb.
Batteries: Two 1.5 volt D cells, and three miniature 45 volt B batteries
Check source: The radioactive check source (see the plate on the side of the case in the top photo) is either missing or has decayed away.
As can be seen in the above photo, there is a connection in the lower left hand corner for headphones. Although the connector is present, the rest of the headphone assembly is missing.
NMC Brochure. Geiger and Scintillation Counters. No date.