El-Tronics PR-31 Scintillation Counter (mid to late 1950s)

The PR-31 Scintillation Counter was produced in the mid to late 1950s by El-Tronics Inc., of Philadelphia. It was also marketed by Sears and the latter version is probably more frequently encountered. As you can see, the PR-31 bears a striking resemblance to the Model 111 produced by Precision Radiation Instruments of Los Angeles.

Quoting a 1955 advertisement: "Super Scintillation Counter with Pistol Type Probe.  An amazingly fine and ultrasensitive instrument that is more than 100 times as sensitive as a geiger counter! Used by U.S. Atomic Energy Commission. No special training needed to operate. Just set  -  aim  -  and read meter! Detects even .001 mr/hr radiation charge. Equipped with meter, range switch, calibration control, high-low time constant switch and zero adjustment. Powered by three batteries. Probe measures 3 1/2 inches, tapering to 2 1/2 inches in diameter by 12 inches long. Battery box measures 3 1/2 x 6 x 6 1/2 inches. Weight 10 pounds, 12 ounces  -  balances perfectly in hand when aimed. Uses massive 1" x 1 1/2" sodium iodide crystal. Probe clips to battery box. Furnished with shoulder strap. Model PR-31  -  $499.95."

Detector:  1"  x  1 1/2" NaI crystal 

Range:  0 - 0.006, 0 - 0.02, 0 - 0.06, 0 - 0.2, 0 - 0.6, 0 - 2.0, 0 - 6.0, and 0 - 20 mR/hr

Size:  ca. 4"  x  9"  x  12"

Output:  No speaker but it has a phone jack

Batteries: one 1.5 volt, two 67.5 volt 

Other Controls:  Fast/Slow response; background Zero, On/Off switch.

References  

Advertisement. Saturday Evening Post. July 16,1955. Page 87.

Schematic for El-Tronics PR-31

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Last updated: 05/10/11
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