Sears Tower Model 6157 GM Meter (ca. 1954-1960)
![Sears Tower Model 6157 GM Meter (ca. 1954-1960)](../../../img/museum/survey-instruments/sears-tower-model-6157-gm-meter.jpg)
This GM survey meter was manufactured for the Sears Roebuck Company by El-Tronics Inc. of Philadelphia. A very similar instrument was sold under the El-Tronics name as the Model PR-5. The latter was described in the Atomic Energy Commission Instrument Catalog (RIB-8) as follows: "Portable beta gamma count rate meter with long life geiger tube designed for field survey work in location of radioactive ores and operating entirely from two flashlight batteries."
![Sears Tower Model 6157 GM Meter (ca. 1954-1960)](../../../img/museum/survey-instruments/sears-tower-model-6157-gm-meter-top.jpg)
The above photo shows the GM probe on the left side of the case, this would usually indicate that the individual using it was left handed.
Detector: GM tube, 30 mg/cm2 wall
Range: 0-0.2, 0-2.0 and 0-20 mR/hr
Size: ca. 4" x 8" x 4"
Weight: ca. 5.5 lbs.
Output: No speaker, but it has a phone jack and a small light that flashes according to the count rate
Batteries: Two 1 1/2 volt
Reference
Atomic Energy Commission. AEC Radiation Measuring Instruments, RIB-8 (supplement 2) July 1, 1954, page SGM-111A.