Lionel CD V-700 Model-6b Geiger Counter
and the
CD V777-1 Radiation Detector Kit
This geiger counter is a Civil Defense meter from the 1960's, and is part of the CD V777-1 Radiation Detector Kit. It's a highly sensitive meter capable of measuring both gamma and beta radiation and has three ranges from 0 - 0.5, 0 - 5, and 0 - 50 mR/h. I read that some of these model 6b meters are still in use by emergency agencies to this day. I found this kit ten or more years ago.
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The complete CD V777-1 kit. The most useful items in the kit are the CD V700, its manual, and the headphones. There's a hand written note on the box that says it was last inspected in 1983.
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The CD V700 is in good physical condition. It has its share of nicks in the paint from use, but nothing major. It wasn't working when I got it and I ended up replacing the PCB. At the time spare boards were readily available, but not sure if they still are now days.
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The radioactive check source is under the label on the side of the case, and according to the manual would originally have measured between 1.5 - 2.5 mR/hr with an average of ~2 mR/hr with the beta shield open. The manual says the source is Ra D&E and has a half-life of ~22 years.
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The source on this meter in 2021 reads at ~1.5mR/hr, which makes me wonder if this check source is really Ra D&E, or has been replaced. I don't know how accurate the meter is, but regardless, after nearly 60 years it should read very low. However, there is a typed corrective note in the manual for paragraph 4.2 that refers to the check source as uranium. I would assume that means depleted uranium. I read online that some of these CD V-700 meters had their check sources replaced back in the 1980's, so I think this check source is uranium like the note says.
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This USAF sticker is on the bottom of the meter.
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A side view with the case removed. Looks like something out of Star Trek. The probe on top contains the 6993 GM tube.
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One nice thing about this meter is that it uses only two "D" cell batteries for power. No "B" batteries here.
I found some info online that claimed using modern alkaline batteries, with their steel shells, risked shorting a battery with the metal retainer installed. To be safe I wrapped the retainer to prevent an accident. |
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The PCB contains all the electronics for the meter, except of course the GM tube.
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Other Items in the Kit
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This is the other detector in the kit, a CD V715 Model 1B. It has a casting piece that's broken where the strap attaches, plus the usual paint chips, but otherwise is in good condition. This meter uses one "D" cell and works, but is no where near as sensitive as the CD V700, and if you need this thing to measure radiation levels you're probably in deep do-do.
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Also in the box were these Bendix CD V-742 personal dosimeters and the CD V-750 Model 5b charger for them. These could be worn in a shirt pocket like a pen and were used to track how much radiation someone was exposed to over a period of time. I was able to charge them and zero the meter inside, so the pens and charger are still functional.
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These are the manuals and a later 1984 booklet that were in the box. Looks like the only things missing are the straps for the radiation detectors, assuming they came in the kit.
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Page created 4/22/2021
Last updated 4/23/2021
Last updated 4/23/2021
