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agi62
Italy
5 Posts |
 Posted - 08/03/2013 : 08:59:05
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Hello, I apologize for the bad English,
I have recently purchased the GMC-300 and using it with his probe counts well the CPM but I has replaced his probe with a more sensitive and the calculation it is wrong.
The impulses that enter the GMC-300 are 150 CPMs but the counter visualizes more than 600 CPMs.
For the first 20 seconds after turn ON it visualizes well the impulses, it quickly increases later the number of the impulses.
I have verified the inpulses in entry to the GMC with digital scope and they are correct but the GMC visualizes a wrong number
It seems that:
1) the software mistakes the average for minute (CPM)
or
2) the hardware, over a certain number of impulses, reads badly.
Does the way to resolve the problem?
Thanks. |
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| Reply #1
agi62
Italy
5 Posts |
Posted - 08/04/2013 : 02:10:25
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Is there someone who has verified this issue?
Thanks. |
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| Reply #2
agi62
Italy
5 Posts |
Posted - 08/04/2013 : 13:27:12
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| I have resolved the issue, the management of the input signal is not perfect, now works fine. |
Edited by - agi62 on 08/04/2013 13:28:09 |
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| Reply #3
geny
3 Posts |
Posted - 08/04/2013 : 16:34:07
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I have same issue with a brand new GMC-300 V. 2.38 with original tube. When it go up to 70-80 CPM it displays about the double of correct amount of impulses and takes sometime even more that 15min to go back to background value...
Have you modified the board or software to fix the issue? |
Edited by - geny on 08/05/2013 01:18:58 |
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| Reply #4
agi62
Italy
5 Posts |
Posted - 08/05/2013 : 04:15:58
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quote:
Originally posted by geny
I have same issue with a brand new GMC-300 V. 2.38 with original tube. When it go up to 70-80 CPM it displays about the double of correct amount of impulses and takes sometime even more that 15min to go back to background value...
Have you modified the board or software to fix the issue?
Hello, I have added a 100pF ceramic condenser among the pin 7 and the pin 4 of the U6 (LM393).
Image Insert:
104.33�KB
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Edited by - agi62 on 08/05/2013 04:20:54 |
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| Reply #5
agi62
Italy
5 Posts |
Posted - 08/06/2013 : 01:17:19
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quote:
Originally posted by geny
I have same issue with a brand new GMC-300 V. 2.38 with original tube. When it go up to 70-80 CPM it displays about the double of correct amount of impulses and takes sometime even more that 15min to go back to background value...
Have you modified the board or software to fix the issue?
Hi,
I have not succeeded inserting the photos of the condenser, I send you to this link where I have explained everything:
h**p://radioactivity.forumcommunity.net/?t=50191071&st=60 |
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GMC-300 counter 
