Description
U.S. Army Radiacmeter IM-174A/PD Gamma Survey Meter with CY-2446/PD Carrying Case
Item Overview
This U.S. Army Radiacmeter IM-174A/PD was manufactured by Nuclear Corporation of America under Contract DAAB05-69-C-0762. The photographed example is serial number 07386A and includes its marked CY-2446/PD canvas carrying case. This portable Cold War instrument was designed to measure the high gamma-radiation dose rates expected in contaminated areas following a nuclear detonation or other serious radiological event.
Identification and Features
The olive-drab metal housing has a protected analog meter, external meter-light hood, covered detector section, zero-adjustment control, function lever, battery compartment, operating-instruction plate, and immersion-leakage retrofit label. Army references identify the model under original FSN 6665-999-5145, later formatted as NSN 6665-00-999-5145.
- Model marking: “RADIACMETER IM-174A/PD”
- Photographed serial number: “07386A”
- Manufacturer: “NUCLEAR CORPORATION OF AMERICA”
- Contract marking: “CONTRACT NO. DAAB05-69-C-0762”
- Government marking: “U.S.”
- Control markings: “OFF,” “SET,” “ZERO,” and “CHECK”
- Meter-face markings: “NUCLEAR CORPORATION OF AMERICA” with visible scale values 1, 5, 10, 20, 50, 100, 200, and 500
- Detector marking: “DO NOT REMOVE CAP”
- Battery-cover marking: “BATTERIES” and “UNSCREW,” with directional arrows
- Retrofit label: “IMMERSION LEAKAGE RETROFIT APPLIED”
- Carrying-case stencil: “CASE, RADIACMETER / CY-2446/PD / US”
- Stock number: FSN 6665-999-5145; later NSN 6665-00-999-5145
Operating-Instructions Plate
The attached plate is headed “PRE-OPERATING CHECK” and gives four steps: turn the “OFF-SET” knob to “SET”; hold the lever switch at “ZERO” and turn the knob until the meter reads zero; hold the lever at “CHECK” and confirm that the needle remains steady within the check band, inserting fresh batteries if it does not; and return the knob to “OFF” when the instrument is not in use.
Radiacmeter Function
The IM-174A/PD is a portable tactical gamma survey meter with a documented range of 1 to 500 roentgens, or rad, per hour. Gamma rays pass through the housing and enter a hermetically sealed, air-filled ionization chamber. The resulting electrical signal moves the analog meter across its nonlinear scale, allowing the full range to be read without a range-selector switch. This is a high-range ionization-chamber instrument, not a low-level Geiger counter.
Documented Military Application
Army field guidance identifies the IM-174A/PD as a standalone instrument for radiological area monitoring and survey work. It was not permanently installed in a vehicle or weapon system. Survey personnel used readings from instruments of this type to measure contaminated areas, report dose rates, mark hazards, and help commanders decide where troops could move or operate after nuclear fallout.
IM-174A/PD Product History
The IM-174A/PD followed the earlier IM-174/PD and was standardized under its federal stock number in 1966. Its operator and organizational maintenance manual appeared in 1967. The “69” portion of this example’s Army contract identifies a 1969-era procurement. The later IM-174B/PD retained the same range and operating principle but moved the meter lamp inside the instrument, while the IM-174A/PD used an external lighting hood like the one photographed.
Nuclear Corporation of America History
Nuclear Corporation of America, also known as NUCOR, manufactured military and commercial radiation-detection instruments during the 1950s and 1960s. The company later shifted toward steel production and developed into the modern Nucor Corporation. This radiacmeter comes from the earlier period when radiation instruments were an important part of the company’s government work.
Associated Calibration and Support Equipment
Military maintenance facilities checked the IM-174A/PD with the AN/UDM-2 Radiac Calibrator Set. Its TS-3494/UDM-2 ratemeter assembly exposed the instrument’s detector to controlled reference fields so technicians could compare readings at established calibration points. The attached “IMMERSION LEAKAGE RETROFIT APPLIED” label records a modification intended to improve the instrument’s resistance to water entering its housing.
Cold War NBC-Defense Background
The IM-174A/PD belonged to the larger group of radiac instruments issued for nuclear, biological, and chemical defense. High-range meters measured dangerous external gamma fields, while lower-range meters checked personnel, food, and equipment and pocket dosimeters tracked accumulated exposure. Together, these instruments supported military monitoring, warning, reporting, decontamination, and fallout-survey missions during the Cold War.
History of Use
Army field instructions described the IM-174A/PD as the standard ion-chamber radiacmeter for area monitoring and survey and stated that it was normally issued at one meter per platoon-size unit. Its rugged portable housing and carrying case allowed monitoring teams to take readings while moving through suspected fallout areas. This example’s 1969 contract places it within the Vietnam-era and broader Cold War radiological-defense inventory, but no individual service history is assigned to serial 07386A.
Condition
The photographed radiacmeter retains its olive-drab finish, manufacturer plate, operating-instruction plate, controls, external meter hood, meter glass, detector cap, battery cover, and retrofit label. The housing has scratches, scuffs, edge wear, and scattered paint loss from military handling and storage. The canvas carrying case has a faded but readable stencil, creasing, surface wear, frayed edges, loose or separated stitching, and an internal snap and pocket. No current calibration label is visible, so the item is sold as a historical display instrument. All ordnance is inert.
Ideal For
This marked 1969-contract radiacmeter and carrying case fit collections focused on Cold War electronics, military radiation detection, and U.S. Army NBC-defense equipment.
- Cold War military-equipment collections
- U.S. Army Signal Corps and NBC displays
- Radiation-detection instrument collections
- Vietnam-era equipment displays
- Museums and civil-defense exhibits
- Collectors of Nuclear Corporation of America equipment
Approx length 9", Approx width 6", Approx height 5", Approx weight 3.8lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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