IM-62A/PDR-10A Alpha Survey Meter (ca. 1952-1960)
This neat looking survey meter was produced by Nuclear Instrument and Chemical Corporation for the Radiac set 10D (the company was awarded the contract in 1952). Since the Plexiglas handle could be easily broken, I can't imagine that this version was produced for very long. It was described as an operational unit in the Directory of Radiac Equipment which was printed around 1961 or so, but both the 1975 List of Radiacs in the Navy Program and the 1987 List of Military and Civil Defense Radiac Devices stated that the AN/PDR-10D was obsolete.
Radiological Defense Vol. IV which was published around 1950 describes the prototype of the AN/PDR-10 as "an improved Poppy," i.e., an air-proportional alpha counter. Since air proportional counters are sensitive to humidity, the PDR-10 has a "dehydrator assembly" (the small cylindrical projection) on the front end of the case. This dehydrator is simply a tube containing indicating silica gel. The visible end of the dehydrator consists of a perforated clear plastic plug.
The functional description from the Directory of Radiac Equipment NAVSHIPS 94200.5 (page date September 1956) reads as follows: "The AN/PDR-10A, AN/PDR-10B, AN/PDR-10C and AN/PDR-10D are portable equipments for detecting and measuring the intensity of low-level alpha radiation. Both visual and audible indications are provided by means of an internally illuminated meter and a detachable head set. Provision is made for checking the operation of the equipment. It does not respond to beta or gamma radiation, and is insensitive to light or radio interference."
The Function Switch has four settings: Charge, Off, Battery Condition, and Read. There is also a Discharge switch on the lower right corner of the meter. When the instrument is turned on, the Function Switch is set to Charge in order to charge the high voltage storage capacitor. This causes a corona discharge in the chamber that is indicated by a hissing sound in the headphones and spurious counts. The Function Switch is then set at the BATT COND position and the Discharge Switch activated so that the hissing and counts caused by the corona are eliminated.
Note the hinged metal cover that is used to protect the detector's fragile window when the instrument is not being used to make measurements.
Range: 0-10,000 dpm/150 cm2
Audio: Headphones (no speaker)
Batteries: Two 1.3 volt (RG-4), six 22.5 volt (412)
Size (case): 13" x 4 1/4” x 3 1/4"
Weight: 7.9 pounds without batteries
The AN/PDR 10 was replaced by the AN/PDR-56 alpha scintillator.
- Campbell, D.C., Radiological Defense, Vol. IV Armed Forces Special Weapons Project, Foreword dated January 1950.
- Directory of Radiac Equipment NAVSHIPS 94200.5, no date, ca. 1961-62.
- Naval Electronic Systems Command List of Radiacs in the Navy Program P-9670-1, February 1975.
- Defense Nuclear Agency List of Military and Civil Defense Radiac Devices HQDNA (AR) 3M Revised, August 1987.
- Instruction Book for Radiac Set AN/PDR-10D NAVSHIPS 92162. February 15 1954.