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Civil Defense Geiger Counters
Most Civil Defense Geiger Counters were issued by the United States Civil Defense during the 1960s in the midst of the Cold War in an effort to help prepare citizens for a nuclear attack. Although referred to as geiger counters, most CD devices were radiological survey meters capable of measuring only high levels of radiation that would be present after a nuclear event.
Additional recommended knowledge
CD meters were produced by a number of different firms under contract. Victoreen, Lionel, Electro Neutronics, Nuclear Measurements, Chatham Electronics, International Pump and Machine Works, Universal Atomics, Anton Electronic Laboratories; Landers, Frary, & Clark; El Tronics, Jordan, and Nuclear Chicago are among many of the manufacturers contracted. Regardless of producer, all counters exhibit the same basic characteristics, albeit with slight variations between some production runs: a yellow case with black knobs and meter bezels. All meters had a "CD" sticker on the side of the case.
CD Counters came in a variety of different models, each with specific capabilities:
The CDV-700 also came with a "check source", a bit of a radioactive isotope under a sticker on the side of the unit. The isotope varied with the maker; depleted or natural uranium was common. This produces about 1-2 mR/hr adjacent to the source, a value which is clearly visible on the analog meter as well as audible via the headphones that accompanied the units. This is about 100 x background levels of radiation, and similar to the near-field from an red (uranium oxide glazed) Fiestaware saucer.
The CDV-700, as a true Geiger Counter, is capable of measuring these ambient environmental levels; the ionization-chamber detectors listed below will not register any activity unless a major radiological incident (e.g., nuclear fallout, spent (but not new) reactor fuel-rods, industrial radiography source leakage) occurs.
The CDV-700 came in 7 models: CD V-700 Model 1, CD V-700 Model 2, CD V-700 Model 3, CD V-700 Model 4, CD V-700 Model 6, CD V-700 Model 6A, and CD V-700 Model 6B
Another meter of note is the Kearny Fallout Meter. The plans for this meter were published in Appendix C of Nuclear War Survival Skills by Cresson Kearny from research performed at Oak Ridge National Laboratory. It was designed to be able to be constructed from household materials by someone with moderate mechanical ability on the eve of an attack. The plans are presented in a newspaper printable format.
The United States manufactured approximately 500,000 geiger counters. Britain manufactured about 20,000 of each of its major types, and is second after the U.S. Some instruments were also manufactured by other countries in smaller numbers.
British civil defense instruments: The American instruments dating from the Kennedy administration era were designed to use low voltage transistor electronics, and the batteries are still available today. However, most British civil defense instruments retained until 1982 or later were manufactured from 1953-7, and required high voltage batteries which became obsolete after portable valve radios were superseded by transistor ones. All British Civil Defense instruments were jointly designed by the Home Office and the Ministry of Defense, and were also a military issue. The first large scale British civil defense issue was the geiger counter 'Contamination Meter No. 1', of 1953 . It had 0 - 10 mR/hour range with external probe and headphones. This was designed to use two 120 volt batteries, although those retained until the 1980s had an inverter and used two 1.5 volt standard batteries or a mains electricity supply. The British 'Radiac Survey Meter', No. 1  and 2  date from 1953-6, and require obsolete 15 and 30 volt batteries in addition to a 1.5 volt standard cell (which powers the valve heaters and light bulb). These were favored as they had been tested on fallout in Australia after Operation Buffalo nuclear tests, and were retained until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries. In 1982 the British PDRM82 was issued for civil defense. This 'Tricorder'-design PDRM82  is lightweight with an LCD display and a plastic case and has all the electronics including miniature geiger tube (shielded against beta particles) on a single, EMP-hardened, PCB. It was designed by Plessey to use three standard 1.5 volt cells, and is microprocessor controlled with digital readout. The 1958-9 'Quartz Fibre Dosimeter Chargers, No. 1 and 2' were retained until the early 1990s as they do not require batteries at all (they incorporate a simple handle-driven generator). A later British civil defence dosimeter charger was developed by R. A. Stephen Ltd and manufactured from 1967-88, and uses a single 1.5 volt cell. It is similar to American dosimeter chargers.
Info on instruments for civil defense (Italian)
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Civil_Defense_Geiger_Counters". A list of authors is available in Wikipedia.|