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 2.GQ Geiger Muller Counter
 Is a SBT-9 Tube possible in a GMC 320+V5 ?
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Geo-Johnny

Austria
159 Posts

Posted - 06/26/2019 :  11:19:30  Show Profile  Reply with Quote
Hello irradiated friends. Has any of you already successfully installed a SBT-9 tube in a GMC 320 + V5 Geiger counter? I tested a new SBT-9 tube with no changes to the GMC 320 + V5, but it does not work that way. I think the anode resistance (R15 - 3MOhm) is too low. Unfortunately, I can not speak Russian, but I think the anode resistance should be ~ 10MOhm?

Does anyone have a tip, which changes to the hardware would be necessary to use a SBT-9 tube? If that worked, I would like to buy a second GMC 320 + V5 and leave one of the two in the original state.

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Geiger Counters: GMC320+V5 & GMC500+
Geiger Tubes: M4011; SI-3BG; SBT-9; LND712; SBM-20
Reply #1

EmfDev

948 Posts

Posted - 06/26/2019 :  12:21:52  Show Profile  Reply with Quote
There have been few discussions about sbt-9:

https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=3395&SearchTerms=sbt-9

https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=3549&SearchTerms=sbt
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Reply #2

Geo-Johnny

Austria
159 Posts

Posted - 06/26/2019 :  22:20:44  Show Profile  Reply with Quote
Thanks for the linked topics, but that does not really help. The older GMC models have a different wiring and layout. A potentiometer for adjusting the anode voltage is not available on the GMC 320 + V5. A wiring diagram of the Geiger counter in the area of #8203;#8203;the counter tube would bring more information. Maybe the difference between the M4011 and the SBT-9 tube is too big to solve in a simple way?

Geiger Counters: GMC320+V5 & GMC500+
Geiger Tubes: M4011; SI-3BG; SBT-9; LND712; SBM-20
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Reply #3

EmfDev

948 Posts

Posted - 06/28/2019 :  09:17:33  Show Profile  Reply with Quote
Sorry I have no experience with the SBT-9 tube, but our engineer said that it should work.
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Reply #4

Geo-Johnny

Austria
159 Posts

Posted - 06/28/2019 :  21:47:15  Show Profile  Reply with Quote
Is there any chance over the support to get a schematic of the GMC 320+? The area around the counter tube and the high voltage part would be enough. That would certainly help also the colleagues from Canada in the parallel thread, which is also looking for a way to realize on the new board layout a SBT-9 counter tube.

Geiger Counters: GMC320+V5 & GMC500+
Geiger Tubes: M4011; SI-3BG; SBT-9; LND712; SBM-20
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Reply #5

EmfDev

948 Posts

Posted - 07/01/2019 :  14:26:35  Show Profile  Reply with Quote
There is a part of the schematic on this thread.

https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=5461&whichpage=2
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Reply #6

Geo-Johnny

Austria
159 Posts

Posted - 07/02/2019 :  00:01:13  Show Profile  Reply with Quote
Thank you for information.
My SBT-9 Tube working now, but i have just 0,01uS/h Background.
And the GMC must have an other calibration, with ~ 0,0116 conversation.

Geiger Counters: GMC320+V5 & GMC500+
Geiger Tubes: M4011; SI-3BG; SBT-9; LND712; SBM-20
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Reply #7

EmfDev

948 Posts

Posted - 07/02/2019 :  11:27:42  Show Profile  Reply with Quote
Yes you need to re-calibrate the unit.
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Reply #8

vikisonline

Canada
3 Posts

Posted - 07/05/2019 :  18:40:04  Show Profile  Reply with Quote
What did you do to get it to work?

I finally got my SBT-9 and put it in with no modifications.

I get about 16CPM background radiation, same as with the m4011.

Which is weird. I couldn't get any higher readings with anything. Tried some stone and tritium sights. Maybe will try some smoke alarms soon.

Edited by - vikisonline on 07/05/2019 18:50:46
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Reply #9

Geo-Johnny

Austria
159 Posts

Posted - 07/05/2019 :  22:07:33  Show Profile  Reply with Quote
quote:
Originally posted by vikisonline

What did you do to get it to work?

I finally got my SBT-9 and put it in with no modifications.


I have not changed anything and the SBT-9 counter tube works. I just tested gamma radiation with a piece of Torbernite. For alpha radiation, I have no material. But I think the SBT-9 counter tube is not so sensitive as the M4011 because it hardly shows any background radiation.

Unfortunately, I still have too little experience with the whole matter. That's why I want to buy a second GMC counter to try more. Basically, I think that the M4011 tube is optimally tuned for the GMC meters and the SBT-9 could only be an addition to the measurement of alpha radiation.

I would like to buy the GMC 600+ meter. But the price and the shipping costs to Europe are too expensive for me. I hope that Amazon Germany someday offers a reasonable price for the GMC 600+.

Geiger Counters: GMC320+V5 & GMC500+
Geiger Tubes: M4011; SI-3BG; SBT-9; LND712; SBM-20
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