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 Evansville IN 1865 CPM, What's occurring there?? 
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Joined: Wed Oct 23, 2013 4:18 pm
Posts: 15
Does anyone know why the CPM are extremely high in Evansville IN? Data charts show since Feb 27, the CPM have spiked to levels above 3000...
Is this a mistake?


Sun Mar 02, 2014 8:41 pm
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Joined: Mon Jan 28, 2013 7:40 pm
Posts: 2856
Location: Illinois
I believe the geiger tube is failing.

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MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Sun Mar 02, 2014 11:06 pm
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Joined: Sun Dec 01, 2013 12:28 pm
Posts: 8
There is something wrong with my counter. When I first turn it on, I get normal background 20 - 30 CPM. But the longer it is on, the higher the readings go. After a few days of constant operation it will be in the 1000s, and higher. If I turn it off and let it sit a while, then everything is back to normal.

I did a radon count on the house and the levels are well below concern.

I don't trust the counter anymore so I took it off line.


Mon Mar 17, 2014 7:05 am
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Joined: Thu Mar 06, 2014 1:25 pm
Posts: 182
Question...

When a GM tube fails, does it exhibit high counts? ...typically???

Is that unit mounted upon a filter element?

Has it somehow become polluted/contaminated ???

...Maybe replace with an SBM-20???

Best
rc


Mon Mar 17, 2014 12:43 pm
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Location: Illinois
timinin wrote:
There is something wrong with my counter. When I first turn it on, I get normal background 20 - 30 CPM. But the longer it is on, the higher the readings go. After a few days of constant operation it will be in the 1000s, and higher. If I turn it off and let it sit a while, then everything is back to normal.

I did a radon count on the house and the levels are well below concern.

I don't trust the counter anymore so I took it off line.


What does your geiger counter units display read during the times NETC software is showing those high readings?

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Mon Mar 17, 2014 6:47 pm
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Joined: Fri May 31, 2013 8:12 pm
Posts: 66
rustycase wrote:
Question...

When a GM tube fails, does it exhibit high counts? ...typically???

Is that unit mounted upon a filter element?

Has it somehow become polluted/contaminated ???

...Maybe replace with an SBM-20???

Best
rc


In my experience with many different GM tubes, when a tube dies it will usually count way high or not at all....but I have had a dodgy SBM 20 count normal initially only to build up a runaway cascade of counts over hours.
Also, during periods of extreem humidity it is not unusual for my gammaScouts to count like crazy - for weeks! - which makes for a pretty useless GC....
It seems to me, from reading netc forums, that there are a high proportion of faulty GMC units being sold. Just saying.

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My Station Location : http://www.netc.com/map5.php?ll=-43.1618524,147.07710599999996 - Tasmania, Australia.


Thu Mar 20, 2014 5:20 pm
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Joined: Thu Mar 06, 2014 1:25 pm
Posts: 182
Thanks, eat.

...there is SO MUCH I just don't know about!

I'm an accomplished tool junkie, but where do you stop?
Backups for backups, regular calibration?
There's just no end to it...

Thank you for your presentation.
rc


Thu Mar 20, 2014 5:26 pm
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