suggestions for setting up a dosimeter charging system...

[Juan S]

I am in the process of trying to set up a reliable dosimeter charger
system for a relative. The type of dosimeter I\'m speaking of are the
pen looking devices that are zeroed after exposure to radiation so that
they can be reused over and over agin. There are a couple of types of
\"chargers\" used for this process:

https://pim-resources.coleparmer.com/item/l/radiation-alert-the-charger-radiation-dosimeter-charger-8192200.jpg

https://i.ebayimg.com/images/g/9X0AAOSwcm5fNxcf/s-l1600.jpg

I personally own the first type above (the coleparmer unit). It doesn\'t
need power, and uses a piezoelectric element that is pressured to
produce charging, then can be bled off until the dosimeter is zeroed.
However, I got mine in a trade deal with a bunch of other equipment, so
it was essentially free. What I like most about it is that it doesn\'t
need any kind of power source for charging dosimeters unlike the second
yellow one above that needs a 1.5V battery.

It is the type I own that I had hope to obtain for a relative too, but
at the prices I see them go for, it is out of the question! So, that
leaves the yellow ones that use a 1.5V battery. I do happen to own a
couple of those, but find them much harder to use than the trigger
charger. I was considering modifying it so that it wouldn\'t have to use
a 1.5V battery. Only a bendix 643 (CDV 750 model 1) used a pump charger
that must have been similar to the trigger charger I use, but I have yet
to see one in the used marker. How would you go about modifying an
existing charger so no battery would be needed?

Thanks in advance for your help.

 

[Peter W.]

https://www.amazon.com/Jordan-Radiological-Dosimeter-Chargers-Bendix/dp/B076746ZG8 I actually have this set (only four pens, however). It came as a set with a geiger-counter that I snagged at a flea.

If you want to make the charger stationary, it is simply a matter of delivering the proper DC voltage - which I dimly remember is supplied by one D-sized cell in the container. And as these were based on conventional Leclanche cells, that would be 1.56 volts DC. That should not be too difficult. But, of course, you would need some power from some source. That, sadly, is the nature of those beasts.

Peter Wieck
Melrose Park, PA

 

[Jeff Layman]

On 17/01/2022 14:34, Juan S wrote:

I am in the process of trying to set up a reliable dosimeter charger
system for a relative. The type of dosimeter I\'m speaking of are the
pen looking devices that are zeroed after exposure to radiation so that
they can be reused over and over agin. There are a couple of types of
\"chargers\" used for this process:

https://pim-resources.coleparmer.com/item/l/radiation-alert-the-charger-radiation-dosimeter-charger-8192200.jpg

https://i.ebayimg.com/images/g/9X0AAOSwcm5fNxcf/s-l1600.jpg

I personally own the first type above (the coleparmer unit). It doesn\'t
need power, and uses a piezoelectric element that is pressured to
produce charging, then can be bled off until the dosimeter is zeroed.
However, I got mine in a trade deal with a bunch of other equipment, so
it was essentially free. What I like most about it is that it doesn\'t
need any kind of power source for charging dosimeters unlike the second
yellow one above that needs a 1.5V battery.

It is the type I own that I had hope to obtain for a relative too, but
at the prices I see them go for, it is out of the question! So, that
leaves the yellow ones that use a 1.5V battery. I do happen to own a
couple of those, but find them much harder to use than the trigger
charger. I was considering modifying it so that it wouldn\'t have to use
a 1.5V battery. Only a bendix 643 (CDV 750 model 1) used a pump charger
that must have been similar to the trigger charger I use, but I have yet
to see one in the used marker. How would you go about modifying an
existing charger so no battery would be needed?

Thanks in advance for your help.

Totally off-the-wall suggestion. Is there any way that a piezoelectric
gas lighter could be used or modified to charge the dosimeter? No
batteries required and only a dollar or two to buy.

--

Jeff

 

[Peter W.]

Totally off-the-wall suggestion. Is there any way that a piezoelectric
gas lighter could be used or modified to charge the dosimeter? No
batteries required and only a dollar or two to buy.

With that in mind, how about one of those anti-static devices for records?

https://www.amazon.com/Zerostat-Anti-Static-Instrument/dp/B074XLBNDD

Bit pricey, however.

Peter Wieck
Melrose Park, PA

 

[Juan S]

On 1/17/22 10:50 AM, Peter W. wrote:

https://www.amazon.com/Jordan-Radiological-Dosimeter-Chargers-Bendix/dp/B076746ZG8 I actually have this set (only four pens, however). It came as a set with a geiger-counter that I snagged at a flea.

If you want to make the charger stationary, it is simply a matter of delivering the proper DC voltage - which I dimly remember is supplied by one D-sized cell in the container. And as these were based on conventional Leclanche cells, that would be 1.56 volts DC. That should not be too difficult. But, of course, you would need some power from some source. That, sadly, is the nature of those beasts.

Peter Wieck
Melrose Park, PA

No, I\'m trying to get away from having to use the battery. Something
like a crank generator. The original Bendix model from the 50\'s had
such a generator built in. It is 1.5VDC, yes and a single D cell.

 

[Juan S]

On 1/17/22 12:37 PM, Peter W. wrote:

Totally off-the-wall suggestion. Is there any way that a piezoelectric
gas lighter could be used or modified to charge the dosimeter? No
batteries required and only a dollar or two to buy.

With that in mind, how about one of those anti-static devices for records?

https://www.amazon.com/Zerostat-Anti-Static-Instrument/dp/B074XLBNDD

Bit pricey, however.

Peter Wieck
Melrose Park, PA

I believe my hand trigger charger has such an element in it. It\'s not
like a lighter that has an instant trigger mechanism, but more like the
Zerostat unit, so a gradual charging, depending on how fast or slow the
trigger is pulled.

I wish such a piezo element was available as a part somewhere, but I
have been unable to locate one. When I was a kid, I actually had a unit
like the Zerostat that my dad picked up for me at a surplus place. It
must have been thrown out years ago because I haven\'t see it since
adulthood.

 

[Chris Jones]

On 18/01/2022 01:34, Juan S wrote:

I am in the process of trying to set up a reliable dosimeter charger
system for a relative.  The type of dosimeter I\'m speaking of are the
pen looking devices that are zeroed after exposure to radiation so that
they can be reused over and over agin.  There are a couple of types of
\"chargers\" used for this process:

https://pim-resources.coleparmer.com/item/l/radiation-alert-the-charger-radiation-dosimeter-charger-8192200.jpg


https://i.ebayimg.com/images/g/9X0AAOSwcm5fNxcf/s-l1600.jpg

I personally own the first type above (the coleparmer unit).  It doesn\'t
need power, and uses a piezoelectric element that is pressured to
produce charging, then can be bled off until the dosimeter is zeroed.
However, I got mine in a trade deal with a bunch of other equipment, so
it was essentially free.  What I like most about it is that it doesn\'t
need any kind of power source for charging dosimeters unlike the second
yellow one above that needs a 1.5V battery.

It is the type I own that I had hope to obtain for a relative too, but
at the prices I see them go for, it is out of the question!  So, that
leaves the yellow ones that use a 1.5V battery.  I do happen to own a
couple of those, but find them much harder to use than the trigger
charger.  I was considering modifying it so that it wouldn\'t have to use
a 1.5V battery.  Only a bendix 643 (CDV 750 model 1) used a pump charger
that must have been similar to the trigger charger I use, but I have yet
to see one in the used marker.  How would you go about modifying an
existing charger so no battery would be needed?

Thanks in advance for your help.

I don\'t have a suggestion, but I am curious - what use has your relative
found for the dosimeters? I have one without a charger, but it was
charged when I received it and has barely discharged in the many years
that I have owned it, and I hope it never will (or not when I am near it
anyway!) Its full-scale reading is a fairly decent fraction of a lethal
dose IIRC.

 

[Juan S]

On 1/18/22 12:36 AM, Chris Jones wrote:

I don\'t have a suggestion, but I am curious - what use has your relative
found for the dosimeters? I have one without a charger, but it was
charged when I received it and has barely discharged in the many years
that I have owned it, and I hope it never will (or not when I am near it
anyway!) Its full-scale reading is a fairly decent fraction of a lethal
dose IIRC.

It\'s ok, I\'ve been asked that before. Well, with things being what they
are in the world lately, I\'ve been trying to set up not only myself, but
a relative or two as well with some radiation monitoring systems. The
idea with the pens and chargers is that, in the awful event a large
scale nuclear event occurs, that we might increase our chances of
survival. As I write I doubt that our odds would be that get to even
get to the point of monitoring (we are all within 50 miles of major
cities and military bases), but just as a precaution. I have seen all
of this CD equipment for years and decided to go with a bunch of the
pens and chargers in a trade. Something high level is definitely needed
because most \"geiger counters\" would be useless after such an event. We
all have geiger counters, but I doubt any of them would even survive an
EMP. I have some low range pens as well, only up to the 200 mR range
that might come in handy for less severe events, such as atomic plant
incidents. Oh well, these are just some ideas and precautions that have
cost next to nothing to try implementing. I don\'t really trust that
batteries would be all that reliable after a crisis, which was why I was
looking for a non-powered way to allow the 1.5V chargers to still work.

 

[Peter W.]

OK - Let us address each concern in turn:

Battery reliability: Solar cells come immediately to mind. It would not take many, and you could set up for the current you need. Install with a rechargeable, and you are all set.

EMP: Those little CD Geiger counters are both incredibly simple and designed for survival. The mil-spec. ones are even better that way. A larger concern would be whether the counter could give you meaningful readings for Alpha and Beta particles - mostly harmful only if the producing materials were ingested or inhaled. Gamma radiation can be detected in any number of simple ways, no batteries needed.
https://www.google.com/search?q=electroscope&oq=electroscope&aqs=chrome..69i57j0i512l9.5040j0j7&sourceid=chrome&ie=UTF-8 Note that Plutonium is primarily an Alpha emitter - and the basis for most nuclear weapons these days.

Dosimeters: Those dosimeters will be useful only if you *know* there is a danger, and therefore pay attention to them, not so much that they indicate (they will), but the period of time it takes them to indicate. Note that they are useless for Alpha and Beta particles, as they are too well shielded.. A piece of heavy aluminum foil is sufficient shielding for either - but for the inhalation issue.

50 miles of an \'target\': That would apply to most of us. And if one is within several hundred miles, but east of a detonation, the radioactive products will catch up to you in any case, unless you choose to not breathe.

Survival: No modern medication, including statins, blood pressure medicine, epi-pens, antibiotics, vaccinations, nor any other infrastructure-dependent materials after the immediately existing supply is used up. Note that these materials have a relatively short shelf-life, so stockpiling is impractical. Then it gets down to supermarkets, transportation, human predators and the other wonders associated with a collapsed civilization. If your survival is based on a FBO, you will be subject to siege - and that is 100% a losing battle, 100% of the time. History has proven that over and over. And if you are nomads, fuel (vehicles) or food (animals) become a serious issue. As well as being highly visible and high-value targets.

Best to work towards preventing Armageddon, rather than preparing for it. Spend that energy on something more joyful than the collapse of civilization..

Nuclear Plant Accidents: See electroscope above. If there is enough ionizing radiation released to do you harm, that little device will indicate pretty much instantly. Meaning that you will have to \'get out\' along with everyone else, and have somewhere to go. At which point, only a Chernobyl-level event is any real threat outside of that \'magic\' 10-mile perimeter, or 20 miles +/- downwind.

NOTE: We keep a mil.-spec. Geiger counter, as in the past, my wife was fond of Fiesta Ware, some colors of which are radioactive. Not so as to be harmful, but one does not wish to eat from them. And before the hospital I work beside closed down in 2019, the radiation-safety people wore dosimeters routinely as they worked around radioactive materials used for cancer treatments.

Peter Wieck
Melrose Park, PA

 

[Jeff Liebermann]

On Mon, 17 Jan 2022 15:32:20 -0500, Juan S <none@anytime.net> wrote:

No, I\'m trying to get away from having to use the battery. Something
like a crank generator. The original Bendix model from the 50\'s had
such a generator built in. It is 1.5VDC, yes and a single D cell.

If a hand clank generator is acceptable, then a hand crank cell phone
charger should be a good starting point. Plenty to choose from:
<https://www.ebay.com/sch/i.html?_nkw=hand+crank+dynamo+charger>
These will deliver 5.0VDC at about 0.5A. To use it in place of a
battery, you need some way to reduce the voltage to 1.5VDC. This is
called a \"buck inverter\" (as opposed to a \"boost inverter\"). These
should work:
<https://www.ebay.com/itm/122361481012>
<https://www.ebay.com/itm/175088753307>
<https://www.ebay.com/itm/401752426156>
To avoid having to simultaneously crank the generator while taking a
reading, I suggest you add a large value capacitor to the 5V input to
retain some charge while the generator is idle. I\'m not sure of a
good value but something like a 3300uF 16V electrolytic capacitor
should be adequate. If it doesn\'t run the dosimeter reader long
enough, increase the capacitance or add some additional capacitors in
parallel.

I have set of 4 dosimeters and a CD V-750 reader. I made the mistake
of storing them with D size alkaline cells installed. The alkaline
cells all leaked and did quite a bit of damage. Anything you can do
to eliminate alkaline cells is probably a good idea. For the matching
CD-V500 Geiger counter, I simply installed a 14500 LiIon cell (with a
1N4007 diode in series to drop the voltage slightly) in place of the
two D cells in series and a AA to D size adapter.
<https://www.ebay.com/itm/362743539090>
For charging, I installed a charging connector in the case and use an
external charger.

Doing something similar for the dosimeter reader is more difficult
because of the lack of LSD (low self discharge) 1.5V cells. I\'ll
probably need to build a LiIon 7.4v (two cells) to 1.5V buck inverter.
Currently, I\'m using a single Lithium cell:
<https://www.amazon.com/Energizer-Ultimate-Lithium-AA-Batteries/dp/B008OII4TY>
and a AA to D size adapter. It\'s been stored in the reader for about
1.5 years so far. No leaks and no loss of open circuit cell voltage.

One more hint. If you\'re really preparing for a full blown nuclear
disaster, make sure that your equipment can operate in very high
levels of radiation. Most equipment does not do well, will overload
easily, and produce either no reading or a useless reading.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Chris Jones]

On 19/01/2022 00:54, Juan S wrote:

On 1/18/22 12:36 AM, Chris Jones wrote:


I don\'t have a suggestion, but I am curious - what use has your
relative found for the dosimeters? I have one without a charger, but
it was charged when I received it and has barely discharged in the
many years that I have owned it, and I hope it never will (or not when
I am near it anyway!) Its full-scale reading is a fairly decent
fraction of a lethal dose IIRC.


It\'s ok, I\'ve been asked that before.  Well, with things being what they
are in the world lately, I\'ve been trying to set up not only myself, but
a relative or two as well with some radiation monitoring systems.  The
idea with the pens and chargers is that, in the awful event a large
scale nuclear event occurs, that we might increase our chances of
survival.  As I write I doubt that our odds would be that get to even
get to the point of monitoring (we are all within 50 miles of major
cities and military bases), but just as a precaution.  I have seen all
of this CD equipment for years and decided to go with a bunch of the
pens and chargers in a trade.  Something high level is definitely needed
because most \"geiger counters\" would be useless after such an event.  We
all have geiger counters, but I doubt any of them would even survive an
EMP.  I have some low range pens as well, only up to the 200 mR range
that might come in handy for less severe events, such as atomic plant
incidents.  Oh well, these are just some ideas and precautions that have
cost next to nothing to try implementing.  I don\'t really trust that
batteries would be all that reliable after a crisis, which was why I was
looking for a non-powered way to allow the 1.5V chargers to still work.

Thanks, fair enough.

I think you could rely on some Eneloop cells if you swap them for a
freshly charged one every year or two. Check that the voltage is
sufficient if the device was designed for 1.5V. Alkalikes would also do
if you could find good ones, but ones made in the last few years seem to
leak.

 

[danny burstein]

In <anfeugpj7a2pdsg1m2tr3kp333kb04p6gc@4ax.com> Jeff Liebermann <jeffl@cruzio.com> writes:

[snip]

One more hint. If you\'re really preparing for a full blown nuclear
disaster, make sure that your equipment can operate in very high
levels of radiation. Most equipment does not do well, will overload
easily, and produce either no reading or a useless reading.

People, too...



--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]

 

[Dave Platt]

In article <anfeugpj7a2pdsg1m2tr3kp333kb04p6gc@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:

One more hint. If you\'re really preparing for a full blown nuclear
disaster, make sure that your equipment can operate in very high
levels of radiation. Most equipment does not do well, will overload
easily, and produce either no reading or a useless reading.

As I understand it, that\'s the reason that most of the radiation
survey meters in the old Civil Defense kits were ionization-chamber
types. They cover ranges of radiation which are actually harmful or
lethal to humans in a relatively short amount of time (minutes to
weeks). They\'re \"no, you really don\'t want to be here, get the hell
away\" devices, just like the dosimeters.

They don\'t respond well to low levels of radiation (background, NORM,
uranium glass, Fiesta ware, etc.).

Their biggest disadvantage is that they operate at such high
impedances (to measure leakage in the ionization chamber) that they\'re
very sensitive to moisture. As I recall, they\'re supposed to be
\"baked\" periodically to make sure they\'re dry, and then stored sealed
in plastic with a dessicant pack.

The old Civil Defense kits tended to come with a bunch of these
ionization meters, some dosimeters and chargers for them, and one
Geiger counter. The Geiger was intended more as a training device
than as an actual \"when the bombs drop\" tool, due to the problem
you mention... in an actual fallout zone, Geiger counters and
scintillation detectors will probably saturate and read low or
zero.

 

[Peter W.]

They don\'t respond well to low levels of radiation (background, NORM,
uranium glass, Fiesta ware, etc.).

Which is why we have a mil.spec. counter with an \"alpha-detector\" window - an area of very thin material that may be exposed by twisting a cover on the head. And a small side-detector as well.

https://thumbs.worthpoint.com/zoom/images2/1/0116/22/pdr-27s-radiac-set-radiation-detector_1_11509f068d2a4a64e50f0476e7ebab00.jpg is a picture of a similar device. Picks up radium-containing glazes nicely.

Peter Wieck
Melrose Park, PA

 

[Andy Burns]

Peter W. wrote:

we have a mil.spec. counter with an \"alpha-detector\" window - an area of
very thin material that may be exposed by twisting a cover on the head. And a
small side-detector as well.

https://thumbs.worthpoint.com/zoom/images2/1/0116/22/pdr-27s-radiac-set-radiation-detector_1_11509f068d2a4a64e50f0476e7ebab00.jpg

403 forbidden
presumably it doesn\'t like direct linking to the image without having first
received cookies from the main worthpoint site, try

<https://www.worthpoint.com/worthopedia/pdr-27s-radiac-set-radiation-detector-1797223075>

> is a picture of a similar device. Picks up radium-containing glazes nicely.

 

[Jeff Liebermann]

On Tue, 18 Jan 2022 17:19:39 -0800, dplatt@coop.radagast.org (Dave
Platt) wrote:

In article <anfeugpj7a2pdsg1m2tr3kp333kb04p6gc@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:
One more hint. If you\'re really preparing for a full blown nuclear
disaster, make sure that your equipment can operate in very high
levels of radiation. Most equipment does not do well, will overload
easily, and produce either no reading or a useless reading.

As I understand it, that\'s the reason that most of the radiation
survey meters in the old Civil Defense kits were ionization-chamber
types. They cover ranges of radiation which are actually harmful or
lethal to humans in a relatively short amount of time (minutes to
weeks). They\'re \"no, you really don\'t want to be here, get the hell
away\" devices, just like the dosimeters.

There are actually two similar looking boxes in the kit. (I can
provide a photo of the kit as soon as I find the box). The C DV-700
geiger counter, which uses a Geiger-Muller tube, and the CD V-715,
which is an ionization chamber:
<https://www.ebay.com/itm/163254194417> (I paid $35 for the entire
kit at a local garage sale in 1985, before Chernobyl. Nobody believes
me today).
<http://www.civildefensemuseum.com/cdmuseum2/radkits/cdv700.html>
<http://www.civildefensemuseum.com/cdmuseum2/radkits/cdv715.html>
The photo also shows the quartz wired dosimeters and readers. The
geiger counter is for fairly low radiation levels. The ionization
chamber is for fairly high levels. I\'ve been told that if I need to
use the ionization chamber device, I\'m already dead.

They don\'t respond well to low levels of radiation (background, NORM,
uranium glass, Fiesta ware, etc.).

Yep. The entire range of the geiger counter on X100 is about 1/2 the
first division of meter on the ionization chamber.
<http://www.civildefensemuseum.com/cdmuseum2/supply/radkits.html#compare>

Their biggest disadvantage is that they operate at such high
impedances (to measure leakage in the ionization chamber) that they\'re
very sensitive to moisture. As I recall, they\'re supposed to be
\"baked\" periodically to make sure they\'re dry, and then stored sealed
in plastic with a dessicant pack.

Nope. The ionization chamber is hermetically sealed (sealed by a
hermit):
<https://www.survivalmonkey.com/resources/victoreen-cd-v-715-instruction-and-maintenance-manual.267/download?version=268>
\"The ionization chamber is hermetically sealed to eliminate changes in
sensitivity due to changes in air pressure resulting from altitude
changes, temperature changes, and moisture effects\". (Pg 3)

However, I have seen problems with the phenolic paper PCB used in most
early units. The PCB absorbs enough moisture to cause high resistance
shorts. A few minutes in a toaster oven usually solves the problem.
If I see some flux left on the PCB from a previous repair, I clean it
off with water and alcohol separately, and then coat the area with
some manner of conformal coating or high-voltage corona dope.

The old Civil Defense kits tended to come with a bunch of these
ionization meters, some dosimeters and chargers for them, and one
Geiger counter. The Geiger was intended more as a training device
than as an actual \"when the bombs drop\" tool, due to the problem
you mention... in an actual fallout zone, Geiger counters and
scintillation detectors will probably saturate and read low or
zero.

Today, methinks that some of the higher end radiation survey meters
have an PIN diode gamma ray detector for the higher doses:
<https://www.ssdi-power.com/products/special-devices/radiation-detector-pin-diode/spd9441.html>
<https://www.ssdi-power.com/media/pdf/RC0130B.PDF>
<https://www.ssdi-power.com/media/sp_pdf/AN2011-01_Radiation_PIN_Diode.pdf>
Sensitivity is marginal, but it doesn\'t saturate at higher doses. At
those high levels, it\'s use is mostly as a dosimeter, not a
disintegration counter.
<https://www.maximintegrated.com/en/design/technical-documents/app-notes/2/2236.html>
etc...


--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Dave Platt]

In article <r4kjuglg5hcoq6d508b969h1bk8rq5id5h@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:

The photo also shows the quartz wired dosimeters and readers. The
geiger counter is for fairly low radiation levels. The ionization
chamber is for fairly high levels. I\'ve been told that if I need to
use the ionization chamber device, I\'m already dead.

Yup... or, at the very least, that you\'re likely to be radiation-sick
for some time.

Their biggest disadvantage is that they operate at such high
impedances (to measure leakage in the ionization chamber) that they\'re
very sensitive to moisture. As I recall, they\'re supposed to be
\"baked\" periodically to make sure they\'re dry, and then stored sealed
in plastic with a dessicant pack.

Nope. The ionization chamber is hermetically sealed (sealed by a
hermit):
https://www.survivalmonkey.com/resources/victoreen-cd-v-715-instruction-and-maintenance-manual.267/download?version=268
\"The ionization chamber is hermetically sealed to eliminate changes in
sensitivity due to changes in air pressure resulting from altitude
changes, temperature changes, and moisture effects\". (Pg 3)

However, I have seen problems with the phenolic paper PCB used in most
early units. The PCB absorbs enough moisture to cause high resistance
shorts. A few minutes in a toaster oven usually solves the problem.
If I see some flux left on the PCB from a previous repair, I clean it
off with water and alcohol separately, and then coat the area with
some manner of conformal coating or high-voltage corona dope.

Even though the chamber itself is sealed, there can be leakage
problems if condensation builds up on the area where the probe wire
comes out through the glass seal. That insulator, and the high-megohm
resistors and the ceramic switch assembly are (according to the
manual) all part of the high-impedance circuit. Any contamination
here causes problems, and I\'ve seen condensation have that effect as
well.

I think your approach of an alcohol cleaning, and then good high-Z
conformal coating is probably just the ticket. And, yeah, phenolic-
paper PCBs are rather on the loathsome side, for a bunch of
reasons

I\'ve got an old one of these sitting around in a closet. I\'ve been
thinking of turning it into something more useful by gutting it, and
replacing the ion-chamber system with a small PMT and a plastic
scintillation crystal. It still wouldn\'t be of any real use in a
high-fallout zone but it could make a nice, sensitive survey meter
for looking for NORM of one sort or another.

 

[Jeff Liebermann]

On Thu, 20 Jan 2022 14:02:31 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

Today, methinks that some of the higher end radiation survey meters
have an PIN diode gamma ray detector for the higher doses:
https://www.ssdi-power.com/products/special-devices/radiation-detector-pin-diode/spd9441.html
https://www.ssdi-power.com/media/pdf/RC0130B.PDF
https://www.ssdi-power.com/media/sp_pdf/AN2011-01_Radiation_PIN_Diode.pdf
Sensitivity is marginal, but it doesn\'t saturate at higher doses. At
those high levels, it\'s use is mostly as a dosimeter, not a
disintegration counter.
https://www.maximintegrated.com/en/design/technical-documents/app-notes/2/2236.html
etc...

Also, you use the CMOS sensor in a smartphone as a radiation detector:
\"The suitability of smartphone camera sensors for detecting radiation\"
<https://www.nature.com/articles/s41598-021-92195-y>
Sensitivity is worse than the PIN diode, but either will work in a
high radiation environment.

You can also obtain organic plastic scintillating slabs:
<https://www.crystals.saint-gobain.com/radiation-detection-scintillators/plastic-scintillators#>
Just add a photomultiplier tube.
<https://www.hamamatsu.com/us/en/product/optical-sensors/pmt/index.html>

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Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558