El-Tronics PR-3A GM Survey Meter (1952-1955)
This GM survey meter was manufactured by El-Tronics Inc. of Philadelphia sometime in the early 1950s.
As is the case for a number of El-Tronics GMs, the color-coded meter display changes scale in conjunction with a change in the range switch. The highest range (0-20 mR/hr) is red, the middle range (0-2 mR/hr) is yellow, and the most sensitive scale (0-0.2 mR/hr) is green).
Range: 0-0.2, 0-2.0, 0-20 mR/hr
Size: ca. 5" x 9.5" x 6.5"
Output: No speaker but it has a phone jack
Batteries: Two 1.5 volt, two 45 volt "B" batteries
Atomic Energy Commission. Radiation Instrument Catalog No. 3. Page Date July 1, 1953. Page SGM-18C.