I seem to be getting more people writing me and telling me that they got a good deal on a brand new, in the box, surplus Geiger counter. When they try it out they get no response, not even background readings. Then they ask "why?"
Here's why.
Unless they have a seperate "PROBE" they are NOT Geiger counters.
Radiation detectors like the CD V715 were issued for Civil Defense use.
They were called Survey Meters and were ION Chamber detectors intended to be used in case of an
atomic bomb attack. They figured that after an attack people would have to
stay in shelters until the radiation levels were safe. So because in the
40's and 50's the opinion was that 30 rems a day exposure was all right the
meters were made to detect levels that were considered dangerous. If you
check, you will find that these meters have ranges from 1 R/Hr to X100 R/Hr or
more. Times have changed and today the safe ranges are very much lower.
2Rem/year.
The reason why the surplus meters will not detect background radiation is that background radiation is only about 200 mRem/yr. (A mRem is 1000th of a Rem) if you calculate it to an hourly rate it is only .022 mRems/hr. With a meter that is calibrated to read 1 Rem/hr, you can see that it would look like the meter is not working.
So if your buying a surplus meter to read radiation around the house,DON'T.
BE AWARE OF OLDER Precision 106 and 107 counters bought at auction. Many have bad Geiger tubes damaged by air pressure from being stored in a trunk of a car. They are expensive to replace. About $55.00.
If you think thats bad wait untill you buy one of those fancy
"GUN" type Scintillators and find that the crystal looks like
this:
This will cost you more than $200.00 to get replaced. If the counter is in
good condition otherwise, it could still be a good buy. Don't forget to add
about $70.00 for batteries.
If you want some interesting links about different sources of radiation E-mail me and ask for Radiation Links.agoshy@e-mtech.com