Q: Calibrating a 1962 CD Radiation Meter

[Norm Dresner]

Among the stuff in my father-in-law's basement I found a '1962 "Radiological
Survey Meter" which the manual says is only sensitive to gamma radiation.
"It is designed to be used by radiological Civil Defense personnel
in determining radioactive contamination levels that may result from an
enemy attack or other nuclear disasters."

It's claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".
After changing the battery -- astoundingly for that era it's a single
pentode hybrid vacuum tube & single transistor circuit that runs on a
single D-cell -- it passed it's built in self-check which, according to the
schematic, just assures that the electronic circuitry is working close to
its design point. Since I'm not in a university and don't have any "radium
or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
method of determining if this thing still works. I'd appreciate suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of gamma radiation.

TIA
Norm

 

[Robert Baer]

Norm Dresner wrote:

Among the stuff in my father-in-law's basement I found a '1962 "Radiological
Survey Meter" which the manual says is only sensitive to gamma radiation.
"It is designed to be used by radiological Civil Defense personnel
in determining radioactive contamination levels that may result from an
enemy attack or other nuclear disasters."

It's claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".
After changing the battery -- astoundingly for that era it's a single
pentode hybrid vacuum tube & single transistor circuit that runs on a
single D-cell -- it passed it's built in self-check which, according to the
schematic, just assures that the electronic circuitry is working close to
its design point. Since I'm not in a university and don't have any "radium
or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
method of determining if this thing still works. I'd appreciate suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of gamma radiation.

TIA
Norm

Your best bet would seem to go to a university "nearby" after calling
to be sure they have sources for the sensitivity check.
As long as the GM tube is still OK, the instrument should be fairly
close.
This could be considered a type of collectors item; keep it!

 

[Liui Ganishiapu]

You can buy some items from ebay to test with. If you are getting a click or
two per min, it is picking up background radiation, which means it is
working good. Many meters back then were for post necular war, which means
they only regester very high levels of radiation, which you don't want to be
around anyway. Do you have a make and model # on it?

"Norm Dresner" <ndrez@att.net> wrote in message
news:gB%Bc.17018$OB3.13478@bgtnsc05-news.ops.worldnet.att.net...

Among the stuff in my father-in-law's basement I found a '1962
"Radiological
Survey Meter" which the manual says is only sensitive to gamma radiation.
"It is designed to be used by radiological Civil Defense personnel
in determining radioactive contamination levels that may result from an
enemy attack or other nuclear disasters."

It's claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".
After changing the battery -- astoundingly for that era it's a single
pentode hybrid vacuum tube & single transistor circuit that runs on a
single D-cell -- it passed it's built in self-check which, according to
the
schematic, just assures that the electronic circuitry is working close to
its design point. Since I'm not in a university and don't have any
"radium
or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
method of determining if this thing still works. I'd appreciate
suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of gamma radiation.

TIA
Norm

 

[Jon Elson]

Norm Dresner wrote:

Among the stuff in my father-in-law's basement I found a '1962 "Radiological
Survey Meter" which the manual says is only sensitive to gamma radiation.
"It is designed to be used by radiological Civil Defense personnel
in determining radioactive contamination levels that may result from an
enemy attack or other nuclear disasters."

It's claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".
After changing the battery -- astoundingly for that era it's a single
pentode hybrid vacuum tube & single transistor circuit that runs on a
single D-cell -- it passed it's built in self-check which, according to the
schematic, just assures that the electronic circuitry is working close to
its design point. Since I'm not in a university and don't have any "radium
or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
method of determining if this thing still works. I'd appreciate suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of gamma radiation.


I'm guessing, from the description, that this is an ionization chamber,

not a
Geiger-Muller tube detector. There were dinner plates made in the 70's with
a VERY bright orange glaze made from Uranium. They were recalled, but
some people have kept them around. If you can find one of these at a flea
market, even a small chip will easily trigger a Geiger counter. A whole
plate should be able to give a reading on even a poor ionization chamber
detector.

Another common radiation source is a gas mantle, as in yard lamps and
Coleman lanterns. They have thorium in them. Thoriated Tungsten TIG
electrodes are also radioactive. (I can't remember if this is a Gamma
source or not, though.)

Even household bricks are weak radiation sources, but I suspect way too
weak for such a detector to pick up.

The Geiger-tube detectors usually have a small label on the side marked
"test detector here", which has a suitable source for checking the detector.
The ion chamber units are usually one-piece, so a test source would be
hard to provide, but you might look around and see if there is such a
label present.

Jon

 

"Norm Dresner" <ndrez@att.net> wrote in message news:<gB%Bc.17018$OB3.13478@bgtnsc05-news.ops.worldnet.att.net>...

Among the stuff in my father-in-law's basement I found a '1962 "Radiological
Survey Meter" which the manual says is only sensitive to gamma radiation.
"It is designed to be used by radiological Civil Defense personnel
in determining radioactive contamination levels that may result from an
enemy attack or other nuclear disasters."

It's claimed sensitivity runs from around 0.2 to 500 "roentgens per hour".
After changing the battery -- astoundingly for that era it's a single
pentode hybrid vacuum tube & single transistor circuit that runs on a
single D-cell -- it passed it's built in self-check which, according to the
schematic, just assures that the electronic circuitry is working close to
its design point. Since I'm not in a university and don't have any "radium
or Cobalt 60" laying around the house (AFAIK), I'm stumped as to finding a
method of determining if this thing still works. I'd appreciate suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of gamma radiation.

TIA
Norm

Your meter is not the low level training type. It is the actual
usage kind.

Calibration is expensive. A few hundred dollars at a commercial laboratory
I would guess.

If you live near a nuclar power plant you could run after
a radioactive waste hauling truck and try to get it calibrated to the
trucks postings???? Stay cool looking when you do this though, beccause
you just might be mistaken for a bad guy.

Anyways, nothing in common use in the consumer realm is radioactive
enough to give an indication. You are just out of luck.

 

[Bart Wessel]

On Sun, 27 Jun 2004 23:02:25 +0000 (UTC), "Norm Dresner"
<ndrez@att.net> wrote:

I'd appreciate suggestions
for either a Q&D function-test or a real calibration with a safe source of
around 4 r/hr of gamma radiation.
No need to buy your own radioactive source.

Pay your local fire department a friendly visit. They have meters and
a source to check them. If they are not out on a job, they'll probably
welcome the distraction from daily duties and take the oportunity to
restudy the subject.
Well, that's what happened to me when I visited the guys here... Had a
very interesting lecture on the subject from the Chief! And yes, my
meter worked almost perfectly.

BartW.
Bart.

There may be a 'NOSPAM.' (mind the dot!) in front of my E-mail address.
It is there to fool machines, not people. Please remove it when you want to reply to me personally.

 

[Jim Adney]

On Tue, 29 Jun 2004 22:58:04 +0000 (UTC) Jon Elson
<jmelson@artsci.wustl.edu> wrote:

I'm guessing, from the description, that this is an ionization chamber,
not a Geiger-Muller tube detector.

What's the difference between the two? I thought the G-M tube WAS an
ionization chamber.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Norm Dresner]

"ping" <daniel_thorn@mac.com> wrote in message
news:17beea79.0406302147.4587876f@posting.google.com...

The Roentgen (R) is a unit used to measure a quantity called exposure.
This can only be used to describe an amount of gamma and X-rays, and
only in air. One roentgen is equal to depositing in dry air enough
energy to cause 2.58E-4 coulombs per kg. It is a measure of the
ionizations of the molecules in a mass of air. The main advantage of
this unit is that it is easy to measure directly, but it is limited
because it is only for deposition in air, and only for gamma and x
rays.

What's the probability that X-Rays from a dentist's equipment would possess
enough energy to register in the detector?

Norm