The CD V-700 (often written as "CDV-700") is a Geiger counter that uses probes equipped with Geiger-MÃÆ'¼ller tubes, manufactured by several companies under contract to the US federal civil defense agency Union. in the 1950s and 1960s. While all models adhere to the same size, shape, coloring and form factor, there is a huge difference between the various models and producers over the years CD V-700 is being produced. Many of the earlier units required the use of high-voltage batteries that were outdated, and expressed obsolete in the late 1970s. Then the model uses between two and six of the standard D size batteries.
Tens of thousands of these units are distributed to civil defense agencies of the US state. Although large quantities have been sold as surplus to civilian users, many are still used with first responders and state emergency management agencies today.
Video CD V-700
Characteristics
Cases and Contents
Most of the V-700 CD models are built using two-piece boxes made of cast aluminum and stamped with distinctive yellow paint and the Civil Defense "CD" sticker. The top, die-cast of the box contains a groove around the outer edge for O-ring rubber that makes the case watertight. It often worsens over the years but can be replaced with parts of rubber beads such as those used for installation of household screen windows within their frames. This section also contains a meter, printed circuit board and holder for batteries between two and six D sizes. Attached to the top of the top casing is a carry handle where the probe clip for storage, headphone connector and control knob.
The inside of the unit contains high voltage electronics up to 900 volts, so care is recommended when operating with an open case. This unit weighs about 2.2 kg with 4 D-cell batteries. Models that use other battery quantities will vary according to their weight. At the bottom, the aluminum section stamped in this section is a printed diagram that corresponds to the brand and model of the unit sent in lowercase. In the decades since these units were created, it is common to find the basics of letters transferred between different brands and models, so the diagram may not match the actual mechanical and electrical properties of the unit.
Power is supplied by 2-6 batteries at low voltage, each 1.5 volts, type D, cylindrical shape and estimated to last about 100 hours. The battery has a weight of 150 g. The most commonly used cells are basic primary batteries which are common but rechargeable batteries can also be used. The common alkaline batteries have the most likely disadvantages of corrosive fluid leak when the unit is placed into storage for a long time, so it is advisable to remove the battery for storage.
The units are shipped with a package containing silicone gel to absorb water in the container and maintain the electronic components of the device. This package should be replaced or regenerated in an oven every year.
Unlike many newer devices of this type, CD v-700 is not equipped with visual or sound alarms for too high radiation levels.
Probe
The thin sidewall of a Geiger-Mueller tube that is enclosed in a brass probe body detects beta radiation and gamma radiation with an open detection probe beta shield, or gammas only when the shield is closed. The body of the brass probe has an energy compensation effect on the readings taken from the probe, reducing the over-reporting of events from low energy gamma radiation as can be found with non-compensated GM probes.
In the case of the common Victoreen 6A model, the tubes used in the probe are EON 62l0, metal construction and halogen-quenched. It is sensitive to gamma radiation and hard beta. The tube is about 90 mm. long, has a diameter of 8.5 mm and operates at a relatively high voltage of 900 volts. This tube option is intended to balance between sensitivity and roughness and detect gamma radiation at energy levels between 20 and 1000 Kev. Analog dial is calibrated in millirads per hour and Counts Per Minute (CPM). When new and in calibration, these units can be expected to provide an accuracy of up to /- 10%. There are 3 possible reading sizes: 1 to 1 scale, from 0 to 0.5 mR/h from 0 to 300 C/m; scale from 1 to 10, from 0 to 5 mR/I 0 to 3,000 C/m scale of 1 to 100, from 0 to 50 mR/I 0 to 30,000 C/m.
Near the key is a good rotary switch to turn it on and off to change the scale of use. Apart from the OFF position, the operator is given a choice of 3 possible scales, X100 or X10 or X1 for different radiation levels as mentioned above.
A small number of CD V-700 modified with the addition of a much larger end-window probe to detect alpha radiation other than beta and gammas and which operate at much lower voltages, causing changes in high voltage electronics. These units are redesigned as CDV-700M and are issued on the basis of six units per state emergency management agency. Its primary use is to detect and clean low-level radioactive contamination in the state's RADEF calibration laboratory, although they can be used to detect alpha radiation in the field, if necessary.
Value
CD V-700 is used to detect low radiation levels, 0 mR/h to 50 mR/hr. High radiation fields can saturate Geiger tubes, causing meters to read very low levels of radiation (close to 0 R/h), thus encouraging users to mistakenly believe that conditions are safe when not.
Test
The V-700 CD is also equipped with a "check source", a bit of radioactive isotope under a sticker on the side of the unit. Isotopes vary with maker; depleted or natural uranium is common, although Maintenance Instructions and Guidelines for the Lionel 6B model show that "Radium D E beta source" with an estimated half-life of 22 years is present under the nameplate. This is generated, at the time of mounting on the machine, about 1-2 mR/hr adjacent to the source, a value clearly visible on the analog meter as well as audible through the headphones that accompany the unit. Measured with the probe beta window found and the probe directly in contact with the operational checking source, this is about 100 times the normal sea level background of the radiation, and is similar to the near field of the glass Fiesta-red glass uranium disk. The rate drops back to the background level a few meters from the source. Because the beaks from different sources of different operational checks used vary and since all CD V-700 was made before 1964 and is now approaching half a century, the amount of radiation emitted from the source may be much lower than when the unit was initially removed. Therefore, accurate calibration through the source can not be guaranteed.
The units are calibrated in the factory, but these can drift over time and need to be recalibrated using the adjusting screw inside the casing. The procedure for this will vary from model to model and best done by someone familiar with the radiation metrology equipment and calibration. US state emergency management agencies typically maintain calibration laboratories intended to keep their own country inventory from such devices calibrated and often offer these services to the first state-of-response agencies throughout the state but generally do not offer them to the public.
Maps CD V-700
Use
The CD V-700, as a real Geiger counter, is able to measure the background levels of gamma radiation and detect the presence of beta radiation in the environment, and thus can be used to detect low levels such as radioactive artifacts such as uranium-doped marbles, Fiestaware plates and watch faces radium. This distinguishes them from other civil defense radiation meters such as CD V-715, CD V-717 and CD-V-720, which is an ion space meter that can measure gamma radiation levels far above (up to 500R/h) what CD V- 700 can (up to 50mR/h). In contrast, chamber ion units are very insensitive to low-level gamma radiation with no legally excluded source of radiation that can make them register at all.
The V-700 CD is usually packaged in various combinations with the high-end ion chamber units as listed above in the kit designated CD V-777. In their initial Cold War application, the V-700 sensitive CD will be saturated and thus useless by the expected high levels of radiation after nuclear weapons exchanges. In that setting, it will be the ion chamber unit that receives most of the usage. The main purpose of CD V-700 is as a peaceful time training instrument and to be used in checking the entry of food and shelter for low levels of contamination. Later, when the Cold War mission ended, many of the redesigned V-700 CDs were used as instruments for first responders used at radioactive spills or other incidents.
When the CD V-700 produced for the US government is now over 50 years old, they are slowly being replaced by more modern instrumentation in federal and state stockpiles and these older units are sold as government surpluses. This makes them inexpensive and very common in the US for use by uranium miners, physics teachers, radiation dispersers and others interested in detecting and measuring ionizing radiation.
CD V-700 is a relatively simple device, with a circuit board that uses several dozen electronic components, at most. Thus, CD V-700 is a common target for various upgrades and modifications that allow additional functionality. Most of the parts used are common electronic parts, but some models use transformers and other parts tailor-made only for the manufacture and specific models of the V-700 CD and this is difficult to find and replace. incident failure. Considering their age, CD V-700 is a pretty reliable device and it's usually pretty easy to keep operating from time to time.
Battery limits the temperature range at which the device works from -10 degrees C and 40 degrees C.
Related Models
Victoreen 496
Victoreen produced the Model 496 in 1980 and many were purchased by the US Department of Energy. 496 uses a modified version of the same casing as the V-700 Model 6B CD produced by Victoreen in the 1960s. If the sticker above Model 496 is removed, older civil defense tokens can be found thrown into the top cover. However, the 496 features a number of improvements over one of the older civil defense versions, including modern electronics, BNC connectors or MHV connectors for external probes, built-in speakers with on-off buttons, built-in battery test circuit, and face meter pass in Counts Per Minute for use with various probes. Other 490-series Victoreen models from the same era have similar physical characteristics but vary greatly in their features.
Ludlum "CD V-700 Model 7"
Not a Geiger Counter per se , CD V-700 Model 7 is a kit to upgrade and modernize the Lionel 6B Model, Lionel/Anton Model 6, or Electro Neutronics 6B with electronics derived from the latest version of Ludlum Model 3 Geiger counter. The package includes a new main electronic board with rotary switches, connectors for removable external probes, harness cables and switches to add new functionality and improved reliability for CD V-700 aging. This increase requires a major modification in this case. The Florida State Department of Health has modified a large number of their V-700 CDs to this standard.
Different Manufacturers List, Model and Year of Manufacture
- Nuclear Research Corporation, NRC Model 1, 1954,1955.
- Victoreen Instrument Co., CD V-700 Model 2, 1956.
- International Pump And Machine Works Inc., CD V-700 Model 3, 1957.
- Chatham Electronics, CD V-700 Model 3, 1957.
- Universal Atomics, CD V-700 Model 4, 1957,1958.
- Anton Electronics Labs Inc., CD V-700 Model 5, 1959.
- Anton Electronics Labs Inc., CD V-700 Model 6, 1960.
- Lionel Electronic Laboratories, CD V-700 Model 6, 1960.
- Victoreen Instrument Co., CD V-700 Model 6, 1960.
- Victoreen Instrument Co., CD V-700 Model 6A, 1961.
- Victoreen Instrument Co., CD V-700 Model 6B, 1962.
- Electro-Neutronics Inc., CD V-700 Model 6B, 1962.
- Lionel Electronic Laboratories, CD V-700 Model 6B, 1962.
- Victoreen Instrument Co., Model CD V-700 Model 6A Extended Range.
- Victoreen Instrument Co., CD V-700 Model 6B, Expanded Reach Model.
References
Source of the article : Wikipedia
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