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Posted by DoN. Nichols on April 11, 2008, 6:24 pm
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> On Thu, 10 Apr 2008 21:10:08 -0700 (PDT), Fred the Red Shirt
>
[ ... ]
>>> 1274 dosimeter used to measure exposure to nuclear radiation. The charging
>>> unit is missing.
[ ... ]
>>Yes. It is based on the Leydon jar or electroscope. The device is an
>>air-spaced capacitor, and the rate at which it loses charge depends on
>>the electrical conductivity of the gas inside.
[ ... ]
>>They were still used as late as the 1980s as they could be directly
>>read without any processing unlike a film badge or crystal dosimeter.
>>
>>I should say they were still used in the US. The Soviets pretty much
>>never used them which is why the lost as many people a they did
>>at Chernobyl. $10.00 each, dirt simple technology to save a life.
>
>
> I have several sets of these, along with other rad detectors, which I
> keep in working shape.
I've got a couple of related ones. They have the HV friction
charger built-in. One holds a charge nicely, the other leaks down
fairly quickly.
Enjoy,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Posted by Gunner on April 12, 2008, 12:02 am
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wrote:
>> On Thu, 10 Apr 2008 21:10:08 -0700 (PDT), Fred the Red Shirt
>>
>
> [ ... ]
>
>>>> 1274 dosimeter used to measure exposure to nuclear radiation. The charging
>>>> unit is missing.
>
> [ ... ]
>
>>>Yes. It is based on the Leydon jar or electroscope. The device is an
>>>air-spaced capacitor, and the rate at which it loses charge depends on
>>>the electrical conductivity of the gas inside.
>
> [ ... ]
>
>>>They were still used as late as the 1980s as they could be directly
>>>read without any processing unlike a film badge or crystal dosimeter.
>>>
>>>I should say they were still used in the US. The Soviets pretty much
>>>never used them which is why the lost as many people a they did
>>>at Chernobyl. $10.00 each, dirt simple technology to save a life.
>>
>>
>> I have several sets of these, along with other rad detectors, which I
>> keep in working shape.
>
> I've got a couple of related ones. They have the HV friction
>charger built-in. One holds a charge nicely, the other leaks down
>fairly quickly.
>
> Enjoy,
> DoN.
Friction Charger? Ive never seen one of those
Gunner
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Posted by azotic on April 12, 2008, 1:18 am
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> wrote:
>
>>> On Thu, 10 Apr 2008 21:10:08 -0700 (PDT), Fred the Red Shirt
>>>
>>
>> [ ... ]
>>
>>>>> 1274 dosimeter used to measure exposure to nuclear radiation. The
>>>>> charging
>>>>> unit is missing.
>>
>> [ ... ]
>>
>>>>Yes. It is based on the Leydon jar or electroscope. The device is an
>>>>air-spaced capacitor, and the rate at which it loses charge depends on
>>>>the electrical conductivity of the gas inside.
>>
>> [ ... ]
>>
>>>>They were still used as late as the 1980s as they could be directly
>>>>read without any processing unlike a film badge or crystal dosimeter.
>>>>
>>>>I should say they were still used in the US. The Soviets pretty much
>>>>never used them which is why the lost as many people a they did
>>>>at Chernobyl. $10.00 each, dirt simple technology to save a life.
>>>
>>>
>>> I have several sets of these, along with other rad detectors, which I
>>> keep in working shape.
>>
>> I've got a couple of related ones. They have the HV friction
>>charger built-in. One holds a charge nicely, the other leaks down
>>fairly quickly.
>>
>> Enjoy,
>> DoN.
>
> Friction Charger? Ive never seen one of those
>
> Gunner
>
I have seen the piezo charger but never seen one with a buit-in charger.
Could you post a pix of your unit don ? I would really like to see what one
looks like.
If anyones intrested heres a link to what the hand held piezo charger looks
like,
it the one with the handle you squeeze.
http://www.civildefensemuseum.com/cdmuseum2/radkits/cdv750/cdv750s.jpg
Best Regards
Tom.
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Posted by DoN. Nichols on April 12, 2008, 5:39 pm
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>> wrote:
[ ... ]
>>> I've got a couple of related ones. They have the HV friction
>>>charger built-in. One holds a charge nicely, the other leaks down
>>>fairly quickly.
>> Friction Charger? Ive never seen one of those
[ ... ]
> I have seen the piezo charger but never seen one with a buit-in charger.
> Could you post a pix of your unit don ? I would really like to see what one
> looks like.
I would be glad to -- if I could find them. Right now, they are
in the metal housing with the serious Navy surplus Geiger Counter (more
ranges than the little CD ones, and a separate hand-held probe for the
more sensitive ranges. (There is a second, smaller, tube inside the
housing just behind a dimple designed to mark its location.)
Anyway -- I'll try my hand at ASCII graphics to show what they
are like. Be sure to view with a fixed pitch font (like Courier) to
avoid image distortion.
+----------+
++----------------------------------+ |
|| | | <--- Glass/Quartz
++----------------------------------+ | Window
^ +--+| |
| +| || |
Eyepiece / +| || |
Knob----------- +--+| |
+----------+
The knob is threaded onto a flange on the housing. You unscrew it about
a turn and it pops out a short distance. Once you have done that,
turning clockwise moves the pointer towards zero, and turning counter
clockwise moves it towards full scale (500 mR IIRC). Once you have
reached zero, press in with your thumb on the raised center portion of
the knob, and turn it clockwise to thread it back onto the flange so
bumping it won't change the reading.
The whole thing is painted black, except the maker's label, and
a stainless steel spring clip to hold it in your pocket on the opposite
side of the housing at the big end.
The housing is not square when viewed from the end, but rather
two semi-circles joined with straight lines.
> If anyones intrested heres a link to what the hand held piezo charger looks
> like,
> it the one with the handle you squeeze.
>
> http://www.civildefensemuseum.com/cdmuseum2/radkits/cdv750/cdv750s.jpg
I suspect that the one at the lower-left with the pot-metal knob
and the one in the bottom middle with the black knob work in a fashion
similar to mine. But they are a lot larger. I guess that these were
for people who knew enough not to reset the one they were wearing in the
middle of an operation. :-)
Speaking of CD -- are there still CD markers on any modern AM
radio dials? :-)
Enjoy,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Posted by Bruce L. Bergman on April 13, 2008, 8:46 pm
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> Speaking of CD -- are there still CD markers on any modern AM
>radio dials? :-)
Nope - they quit that in the 70's.
We don't have to worry about a swarm of Russkie Bombers coming over
the Polar Route "DEW Line" using commercial AM Radio stations for
Radio Direction Finding to home in on our big cities and deliver us a
"Nookular Present" - they have GPS now, and even dead reckoning can be
done much better.
Synopsis: The whole idea behind "CONtrol of ELectronic RADiation"
was that ALL broadcast TV and radio stations, aircraft beacons, Ham,
Public Service and Business two-way radio would shut down. Total
Radio Silence, all bands. No fixed point signals to home in on.
And many of the larger AM radio stations would have hot TX crystal
ovens and pre-tested tower tuning points (the red-painted spots on the
loading coils and tuning knobs) for quickly switching over to either
640 or 1240 KHz non-directional.
The only radio you would hear would be the regional Civil Defense
emergency instructions as the various stations all swapped off
transmitting them round-robin every few minutes, not announcing call
signs or locations.
RDF doesn't work worth beans if they can turn off every signal you
could use, and the few that remain shift location by 25 miles or more
in a random pattern every 3 minutes.
--<< Bruce >>--
PS: Hold the flames. Yes, I realize that even back then when they
treated the Cold War seriously there is no WAY they could get 100% of
the transmitters turned off for hours - they'd have to send someone
out to the hilltop repeaters and rural translators and physically cut
the cords, and search out the saboteurs sending homing signals... But
CONELRAD was still a sound idea - /for it's time/.
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