Office Of Civil Defense
Item Number CD V-781

Complete Set Out Of Box
Nuclear-Chicago CD V-781 Model 1

Serial Number: 541

From CPG 2-6.2.3  Handbook For Aerial Radiological Monitors

April 1983
In operation, the CD V-781 Aerial Survey Meter is an instrument system comprising the necessary
elements to detect radiation, process the information, provide readout to the operator, and permit
recording of observations for evaluation at the end of the survey mission. If required, the system can
be operated by the pilot alone, but two-man operation (pilot and monitor) is recommended.

The system is designed to resist the shock and vibration associated with normal aircraft operation,
operate at altitudes up to 20,000 feet, and withstand temperature variations from -20º F to 110º F
with a relative humidity of up to 95%. This system can be calibrated to an accuracy within 10% of the
true exposure level for Cs-137 gamma radiation incident to the bottom of the detector case. After
over-exposure to radiation intensity as high as 1,000 R/hr, the system recovers within 1 minute.
These environmental extremes are cited to define the limitations of the system and not as a guide
to operation.

Government price in 1969: $748.41
Government Procurement Fiscal Year 1955 - 1985 1,250

Metering Unit
Metering Unit with Accessories
Mounting Brackets - Headphones - Manuals - Power Jack
Size: 10" wide by 4 1/4" high by 3 3/8" deep.

Metering Unit
Front of Metering Unit

Readout of 0 - 10 Roentgens / Hour
Measurement is done in the detector unit by 3 Geiger Müller tubes.
Meter Scales  -  Left to Right:
0 - 0.1 Roentgens / hour
0 - 1 Roentgens / hour
0 - 10 Roentgens / hour
As the radiation reaches 85% of full scale, the next meter to the right starts to react.
The indicator lights over the right two meters come on when the meter below
 them reaches 85% of full scale, but only when using aircraft supplied power.
Audio output to headphones rises from 250 hertz to 2 kilohertz over the 3 scales.

Inside Metering
Inside Metering Unit

This part gets it's power from the detector unit or simulator unit.
Case is made of aluminum. Schematics are glued to inside of cover.

Detector Unit
Front and back of Detector

Size: 9 " wide by 4 5/8 " high by 7" deep

Inside The Detector
Inside the Detector

This part requires 9 "D" size 1½ volt batteries,
and / or connection to 12 VDC supply from aircraft.

3 Geiger Müller tubes are mounted on a removable board.
If both power sources are used, they are selectable by a switch on the metering unit.
Case is made of aluminum. Schematics are glued to inside of cover.

Front and back of Simulator

Size: 9 " wide by 4 5/8 " high by 7½" deep

Inside Simulator
Inside the Simulator

This part requires 8 "D" size 1½ volt batteries.
This unit is hooked to the metering unit to provide training for the pilot or monitor.
Case is made of aluminum. Schematics are glued to inside of cover.

Recorder Set
Sound Recorder - Reproducer With Accessories

Webcor Inc. Microcorder 300  (Missing Throat Microphone)

Webcor Microcorder 300

The recorder uses 6 "D" size 1½ volt batteries, there is no provision
for connection to 12 VDC supply from aircraft.
Used to provide an audio record of  time, position, altimeter readings and radiation levels.

Additional Items To Be Carried On Aerial Monitoring Missions

According to the Office Of Civil Defense Publication FG-E-5.9.1 (July 1966)
Handbook For Aerial Radiological Monitors

The above instruments are also required for any Aerial Monitoring Mission.
Victoreen CD V-715 Model 1B Survey Meter ***
Left to Right:
(2) Bendix CD V-138 Dosimeters
(2) Landsverk CD V-730 Dosimeters
(2) Bendix CD V-740 Dosimeters

*** Note: a CD V-710 is also acceptable.

According to the FEMA Publication CPG 2-6.2.3 (April 1983)
Handbook For Aerial Radiological Monitors

An aerial radiological monitoring equipment set consists of:
 CD V-781 Aerial Survey Meter
2 each CD V-138  0 - 200 mR Dosimeters
2 each CD V-730 0 - 20 R Dosimeters
2 each  0 - 200 R Dosimeters (this would be CD V-742)

According to:
List of Military and Civil Defense Radiac Devices
August 1969

There was a Nuclear-Chicago CD V-781 Mark II
It would utilize a recycling ion chamber and have a digital readout.
Measurement range :  0-5 mR/hr to 0-25 R/hr
Anybody ever seen one?
The Civil Defense Technical Bulletin (TB-11-20) - Dated 1959
Stated that an aerial/ground high range monitor, identified as the CD V-780, was under development
and that this instrument was to use a scintillator as the detecting element.
 Although the 780 was never produced, a similar instrument for aerial surveys did go into production:
the CD V-781 which employed multiple GM detectors.

FG-E-5.9 (April 1963) FG-E-5.9.1  (July 1966) CPG 2-6.2.3 (April 1983)

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