Radiac Set
IM-74C/PDR-27C
IM-74C/PDR-27C
Measures 0 - 500 milliroentgens Per Hour / 4 Range Scales
The scales are color coded and change using a chain between the control knob and the meter face.
0 - 500 mR = Yellow / 0 - 50 mR = White / 0 -5 mR = Green / 0 -.5 mR = Blue
Measures Gamma, Detects Beta. / Uses 2 Geiger Mueller Tubes
One tube (JAN-5980) is mounted inside, and one (JAN-5979) is external.
The JAN-5979 tube is carried in a holder behind the handle as shown above, and is used for the
two lower ranges of 0 - 5 m/R and 0 - .5 m/R per hour. The external tube is a mica window, which
is covered by a movable sheild. The mica is 0.0005 inches thick.
External probe is marked DT-101/PDR-27F.
Manufactured By: Admiral Corporation / Serial Number: 281
Close-up of meter face with scale set at 0 - 500 Milliroentgens per hour, and battery box.
This model uses (2) BA-401/U 1½ volt dry cells, (1) BA-416/U battery pack,
and (1) BA-413/U battery pack.
Bottom inside view, the internal JAN 5980 Geiger Mueller tube is mounted to the far left side.
The JAN-5980 is used on the 0 - 500 and 0 - 50 mR/hr ranges.
The component layout is glued to the right side.
Inside views, left and right sides.
This unit is complete but un-tested.
Government cost in 1969: $147.75
Note: The AN/PDR-27 series has been replaced by the AN/VDR-2.