IM-179 Miniature Ratemeter

IM-179 Miniature Ratemeter

The IM-179/PD was “a miniature gamma ratemeter for placement in aircrew survival kits” that employed a Neher-White pressurized ion chamber filled with argon. It only used two push button controls: read and test. The meter and dial are luminescent (Ra-226 radioluminescent paint). The instructions on the case are self-explanatory.

Range: 0.02 to 200 R/hr on a single non-linear scale

Size: 2.5” x 4.25” x 1.25”

Weight: ca. 9 oz.

Batteries: The commercial version of this instrument uses one 5.2 volt and one 1.34 volt

Manufacturers: Victoreen Instrument Company, Nuclear Corporation of America, Jordan Electronics, Heat Pipe Corporation of America        

Jordan (and Victoreen) sold a commercial version of this instrument known as the "Minirad." One obvious difference was that the Minirad didn't come with a color-coded scale. The Minirad came in three versions: the Model M-50 (0.005-50 R/hr), Model M-100 (0.01-100 R/hr) and the Model M-200 (0.02-200 R/hr).


  • Defense Atomic Support Agency, List of Military and Civil Defense Radiac Devices. DASA 1243 revised, 1966.
  • Defense Nuclear Agency List of Military and Civil Defense Radiac Devices HQDNA (AR) 3M Revised, August 1987.