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 2.GQ Geiger Muller Counter
 Showing No counts with GMC 300.. what to do??
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United Kingdom
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Posted - 04/03/2018 :  01:52:01  Show Profile  Reply with Quote
I had GMC 300 for the past many years. It used to work fine. But Now it has been sitting in a drawer for years with no battery in it.
Recently I decided to see what was happening with it, and installed a new battery. After it came to life I noticd the right hand side of the display incl the battery level meter display is faded..but more important is zero clicks.
Also i tried to contact [url=h**p://]Toshiba Support UK[/url] for more support.
While testing.. I noted it will count clicks when I touch the Multimeter probes.. I can make it count up to the alarm level of 100 and the alarm goes off. This actually shows the device is working.. but maybe the tube is not. Its had very little use..??
Is it likely its working and I really do have a zero BG radiation??
Also, visit [url=h**p://]Windows Installation Support[/url] for more issues related to your windows.
Reply #1


417 Posts

Posted - 04/07/2018 :  07:51:30  Show Profile  Reply with Quote
It will certainly be wrong if you have zero counts. Expect something beyond 10 CPM, most likely less than 30CPM (if you lived in an area with higher background, you would probably know)

There are may ways these Geiger counters can fail. Since this happened after a longer time of no use, and the batteries are ok (?), chances are the tube is broken. Open the case (careful, high voltage at the tube contacts!) and look at the tube: there should be a faint rainbow shine inside the glass tube (from a vaporized metal deposit). If this is absent, in particular when you see a powdery appearance instead, then most likely the tube is cracked, air came into the tube, and the metal vapor deposit became oxidized. A new tube is needed.

If that is ok, electronic defects are the likely cause; repair is needed.

Edited by - ullix on 04/07/2018 07:52:32
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