Mobilization
Item Number CD V-720
CD V-720 Radiological Survey Meter
The Chatham CH-720 was designed specifically to fulfill the requirements of the Civil Defense High Range
Radiological Survey Meter CD V-720. Utilizing three ranges of 5, 50 and 500 roentgens per hour full scale,
it measures gamma and x-ray radiation fields from 0.5 to 500 roentgens per hour and detects beta particle
radiation even in the presence of such fields. An air-filled ionization chamber serves as the radiation detecting
element. The chamber has a thin window which permits the transmission of beta particles into the chamber
volume, thereby making detection possible. With the window covered by a movable shutter the instrument
responds only to gamma or x-radiation. When the shutter is placed in the open position, the beta window is
exposed and the unit also responds to beta radiation.
The accuracy of the instrument is within ± 15% of true dose rate throughout a temperature range from -20º F
to +125º F. It is also within ± 15% for photon energies from .08 MeV to 1.2 MeV with the beta shutter in
either the open or closed position. It is unaffected by altitude changes up to 25,000 feet.
Government cost in 1969: $23.30
But already obsolete in 1963 ...
Government Procurement - Fiscal Year 1955 - 1985 113,231
Inside View
Chatham Electronics
CD V-720 Model 1
Note that the ion chamber stays with the lower part of the case.
Uses 1 "D" size 1 ½ volt battery and 2 "B" size (Neda Type 215) 22 ½ volt batteries.
This unit is all cast aluminum with schematics inside the case.
Back row, middle in top photograph.
