| T O P I C R E V I E W |
| pinello |
Posted - 10/18/2022 : 12:08:22
Hello everyone. I have bought a GMC 500 plus some weeks ago, I though that i was happy with it, but recently I just discovered that , enabling the CPM1 and CPM2 display on the main large font screen (and when both tubes are enabled) only CPM1 is counting. CPM2 is stuck to 0 all the time. If i do factory reset, then CPM1 and CPM2 are updated (with cpm2 about 10% of the cpm1 reading), but as soon i power-off and power-on , the CPM2 remains stuck to 0 , like it frozen or disabled. I understood reading the threds that this is not the right behavior, am I correct? does some of you noticed the same issue? many many thanks.
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| 2 L A T E S T R E P L I E S (Newest First) |
| pinello |
Posted - 10/19/2022 : 05:14:17
quote:
Originally posted by ullix
Your counter might still be ok.
The second tube in this counter is some 70 times less sensitive than the first tube. So when the first tube counts background at near CPM=20, you are getting on average of 1 count every 3...4 seconds. The 2nd tube would then show 1 count every 210...280 seconds.
You can only verify proper function with a stronger source, like Uranium sample, Thorium sample, or Potassium sample. The latter can use things already in your house, see "Potty Training" here: https://sourceforge.net/projects/geigerlog/files/Articles/
You may have to open the counter for full exposure of the tubes to your sample.
Thanks Ullix for the tips. i will try to get stronger source and see if CPM2 will rise. Thanks! |
| ullix |
Posted - 10/18/2022 : 22:38:33
Your counter might still be ok.
The second tube in this counter is some 70 times less sensitive than the first tube. So when the first tube counts background at near CPM=20, you are getting on average of 1 count every 3...4 seconds. The 2nd tube would then show 1 count every 210...280 seconds.
You can only verify proper function with a stronger source, like Uranium sample, Thorium sample, or Potassium sample. The latter can use things already in your house, see "Potty Training" here: https://sourceforge.net/projects/geigerlog/files/Articles/
You may have to open the counter for full exposure of the tubes to your sample.
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