| T O P I C R E V I E W |
| Shonky |
Posted - 09/21/2025 : 05:34:03
Hi I'm new here, great forum.
I just bought my first geiger counter, a second hand GMC-300s from fleabay and there's something going on which doesn't make sense.
I'm getting background readings mostly between 25 and 35 CPM but 0.00 on the microsieverts/h and the mR/h.
Even with a handful of old thorium mantles, which got the thing clicking away quite merrily, there were only zeros from the dosage settings after an hour.
I think it's a dud but just wanted to check whether I'm missing anything?
Many thanks |
| 2 L A T E S T R E P L I E S (Newest First) |
| 3z_phoenix |
Posted - 09/22/2025 : 04:16:09
yes, i do RTFM :)
pls. open main menue there u find "Init Setup" select this
there u find "Factory Reset"
pls. select this, it should load back all manufacturer defaults
check again with your radio-sources
if still stay the same problem
over this "Factory Reset" u see "Calibration" for check the Values
there not have to be Zero-Values...
in hardware description i found:
High sensitivity tube M4011 installed (user can remove this tube install other tube if needed)
its the same Tube, like my GMC500+ use,
i can give u my calibration values :)
i only worry abit about "a User can remove this tube and install other" bcs. as u wrote your device had a pre-owner...
...hopefully we can get this device back into complete running...
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| 3z_phoenix |
Posted - 09/22/2025 : 03:01:11
hi Shonky,
for me, this sounds like "lost" calibration-data, bcs.
some math is used to convert the CPM-value into microSivert per hour.
please have a look into "initional settings", if you can find something
like "Tube calibration" the value there must exist and no Zero-value.
sorry, i only have a GQ-GMC-500+ and i am not sure what Tube are used
at your device...
but sure our EmfDev will take-over so he read about your problem...
meanwhile i try to study the hardware details about your device...
kind regards, 3z_phoenix |
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