Model 109 "Professional" (1952)
The Precision Radiation
Instruments Model 109, just like the Model 107, was also known as the
“Professional.” The major
difference between the two was that the Model 109 employed an end window
Geiger Mueller detector and was intended for either laboratory work or civil
defense measurements (e.g., of food and water). There was no speaker to
provide an audible signal but there was a covered jack on the top of the
instrument for headphones. The count rate could also be estimated by
observing the small flashing neon light to the left of the meter face. A
locked adjustment on the top of the unit permitted the surveyor to adjust
the calibration. The assigned date of 1952 is based on a July 1952 date on
the instrument calibration curve (attached to the instrument case).
Detector: end window GM tube (1.4 mg/cm2), connected to the meter with a non-detachable cable
Range: 0 –0.2, 0 – 2 and 0 – 20 mR/h.
Batteries: two 1.5 volt, two 45 volt and one 22.5 volt
Dimensions: 3.5” x 4.5” x 6.5”
Price: $199.50 in 1954.
For some reason, maybe it was just a part of being in LA, Precision Radiation Instruments was also in the music business. While none of the PRI-owned labels (Craftsman, Tops, etc) were household names, they did produce records for some reasonably well known entertainers such as Mel Torme and Lena Horne. One PRI 33 1/3 record worth mentioning: "If the Bomb Falls," a primer on surviving a nuclear attack.
Atomic Energy Commission Radiation Measuring Instruments RIB (Part 2) Supplement, page SGM-58A, July 1, 1954.
Precision Instruments catalog, form 1001B, 1954 copyright;
Copyright 1999, Oak Ridge Associated Universities