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 2.GQ Geiger Muller Counter
 GMC-320PLUS display reading Problem
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cobalt60

2 Posts

Posted - 05/14/2016 :  06:29:33  Show Profile  Reply with Quote
Hey there!

today i measured my uranium glas as my Geiger counter went on counting, after reaching the 1000 cpm mark, the µSv/h display jumped from somewhat of 6.xx µSv/h to 3.xx µSv/h (xx = some random values i dont remember). The CPM only display correctly goes on counting (up to 1200 cpm for this uranium glas). Whats the reason for this? is there a major defect? I ordered it 4 weeks ago.
Thank you!
Reply #1

Distelzombie

Germany
202 Posts

Posted - 05/15/2016 :  08:48:51  Show Profile  Reply with Quote
That's the same problem/question I asked in another thread month ago. Just at lower values.
Still got no satisfying answer.


Same problem as in these threads:
- Found working Android App! (No CPM limitation)
- GQ320 Plus after Chornobyl trip - question

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.

Edited by - Distelzombie on 05/15/2016 08:57:51
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Reply #2

rogerroentgen

USA
10 Posts

Posted - 05/15/2016 :  11:39:31  Show Profile  Reply with Quote
I believe this is because of the 3 calibration setpoints. The default Calibration #3 is 1000 CPM @ 5uSv/h. I'm guessing the ratio is changing the calculation once you get over 1000 CPM readings. Consider reading only using CPMs instead of uSv or mR. Maybe you have changed your calibration values for #1 and #2 but not #3 and this throws off the ratio?

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Reply #3

Distelzombie

Germany
202 Posts

Posted - 05/16/2016 :  03:33:04  Show Profile  Reply with Quote
quote:
Originally posted by rogerroentgen

I believe this is because of the 3 calibration setpoints. The default Calibration #3 is 1000 CPM @ 5uSv/h. I'm guessing the ratio is changing the calculation once you get over 1000 CPM readings. Consider reading only using CPMs instead of uSv or mR. Maybe you have changed your calibration values for #1 and #2 but not #3 and this throws off the ratio?





Did you read the thread where I experiment with this problem? :)

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.
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Reply #4

cobalt60

2 Posts

Posted - 05/16/2016 :  07:17:32  Show Profile  Reply with Quote
rogerroentgen no i haven´t changed any calibration values. And it doesnt would make sense to jump to 3 µSv/h, if the 1000 cpm mark is calibrated with 5.xx µSv/h. of course it is to some extent a non linear increase with increasing cpm, but to half the value is for sure an error and no calibration issue.
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Reply #5

Distelzombie

Germany
202 Posts

Posted - 05/16/2016 :  15:10:21  Show Profile  Reply with Quote
It is. Let's hope someone finally recognizes this problem as one. :)

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.

Edited by - Distelzombie on 05/16/2016 15:10:49
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