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From: tm on 25 Apr 2010 15:23
Did you read the information in this link? Scroll down to the
discussion on the regulator tube.

http://www.dvq.com/geiger/heath_rc1.pdf

The 900 volt regulator tube operates in three regions; corona,
glow, and arc. It is sensitive to the high voltage supply conditions,
i.e. ripple can cause it to oscillate between the modes. Also, it is
sensitive to the filter capacitance.






From: Jeff Liebermann on 25 Apr 2010 17:13
On Sun, 25 Apr 2010 17:28:31 +0100, Baron
<baron.nospam(a)linuxmaniac.nospam.net> wrote:

>Hey Jeff,

You rang?

>I've several old valves (Tubes) that are marked as containing "Radio
>Active Material" with a "Do not Break Glass" and a yellow sticker on
>them. CV number marking. Any ideas ?

Tubes are what you roll the toilet paper upon. Valves are what
controls the flushing. What more do you need to know?

>They are stored in a box somewhere. If I can find them I'll come back
>with the CV numbers.

My guess(tm) is a gas filled thyratron or regulator
tube/valve/whatever, where the gas is slightly radioactive to decrease
the ionization voltage. The cathodes were also made with thorium:
<http://www.angelfire.com/electronic/cwillis/rad/tubes.html>
<http://www.tubecollector.org/documents/radioactive.htm>
The 5841 voltage regulator is one of those that is filled with some
radioactive gas. The differences between the various versions, which
breakdown at different voltages, is the amount and type of radioactive
gas or material.


--
Jeff Liebermann jeffl(a)cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
From: Chris F. on 6 May 2010 19:20
I finally got this working, at least to the point where it's now usable. The
trick was to filter the B+ supply between the three tubes, with a
filter+inductor+filter combination, to prevent stray oscillation. It still
generates about 1 stray pulse every 5 seconds or so (not counting normal
background readings), but this may straighten out with some tweaking. Even
if not, the detector is now suitable for measuring above-background levels
of radiation, up to about 20 mr/hr. Should come in handy if the nearby
nuclear power plant ever blows....
Thanks to all for the advice.
"Chris F." <zappyman(a)hotmail.com> wrote in message
news:4bd08a44$0$12419$9a566e8b(a)news.aliant.net...
> I recently bought an old Detectron model DG-7 geiger counter. This is
> from the early 50's and has three 1U5 tubes inside. Power requirements are
> 90 volts for the B+, two "D" cells for the tube filaments, and a 4.5 volt
> bias supply.
> I went over the unit, replacing a selenium rectifier and testing the
> tubes. The unit powers up, but generates a steady stream of pulses on it's
> own, even with the probe detached. The frequency of the oscillation varies
> with the range selector knob. The probe is working - when brought near a
> source (a bunch of vaseline marbles) it will produce extra clicks in
> addition to the stray ones generated by the unit.
> I've checked all the other components - resistors, capacitors, etc. The
> only thing I couldn't check is a very small tube, which looks like a
> cold-cathode rectifier of some kind. I've also tried varying the B+ and
> bias voltages. And I can't find a schematic, which makes matters worse.
> I'm not sure what to do next. Any ideas?
>


From: N_Cook on 7 May 2010 03:32
Chris F. <zappyman(a)hotmail.com> wrote in message
news:4be34ede$0$12426$9a566e8b(a)news.aliant.net...
> I finally got this working, at least to the point where it's now usable.
The
> trick was to filter the B+ supply between the three tubes, with a
> filter+inductor+filter combination, to prevent stray oscillation. It still
> generates about 1 stray pulse every 5 seconds or so (not counting normal
> background readings), but this may straighten out with some tweaking. Even
> if not, the detector is now suitable for measuring above-background levels
> of radiation, up to about 20 mr/hr. Should come in handy if the nearby
> nuclear power plant ever blows....
> Thanks to all for the advice.
> "Chris F." <zappyman(a)hotmail.com> wrote in message
> news:4bd08a44$0$12419$9a566e8b(a)news.aliant.net...
> > I recently bought an old Detectron model DG-7 geiger counter. This is
> > from the early 50's and has three 1U5 tubes inside. Power requirements
are
> > 90 volts for the B+, two "D" cells for the tube filaments, and a 4.5
volt
> > bias supply.
> > I went over the unit, replacing a selenium rectifier and testing the
> > tubes. The unit powers up, but generates a steady stream of pulses on
it's
> > own, even with the probe detached. The frequency of the oscillation
varies
> > with the range selector knob. The probe is working - when brought near a
> > source (a bunch of vaseline marbles) it will produce extra clicks in
> > addition to the stray ones generated by the unit.
> > I've checked all the other components - resistors, capacitors, etc. The
> > only thing I couldn't check is a very small tube, which looks like a
> > cold-cathode rectifier of some kind. I've also tried varying the B+ and
> > bias voltages. And I can't find a schematic, which makes matters worse.
> > I'm not sure what to do next. Any ideas?
> >
>
>

So what have you found for a long-term test source , high enough emitter at
a
repeatable distance, to say give a count at least 5 times more than
background?
I've managed to lose my old broken gas-lighting mantle I had retained for
this purpose




From: Jeffrey D Angus on 7 May 2010 10:35
Chris F. wrote:
> Should come in handy if the nearby
> nuclear power plant ever blows....

Homer Simpson laughing at the "Run for the hills" alert level
on the warning sign at the power plant. "That will never happen."
Lenny asks him if he thought the power plant was safe. "No, if
the plant blows up, there won't be any electricity to power the
sign."

Jeff


--
�Egotism is the anesthetic that dulls the pain of stupidity.�
Frank Leahy, Head coach, Notre Dame 1941-1954

http://www.stay-connect.com
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