| T O P I C R E V I E W |
| Benezi |
Posted - 05/11/2014 : 12:21:28
Hello Guys!
I bought the GMC320+ last week and now I'm a bit confused.
In the Internet it says that the M4011 counts about 30-40 CPM background radiation. But my GMC says only about 10-15.
I calibrated the GMC and it was only half sensitive as it should be refered to the settings when it came last week. My conversion factor for CS-137 now is uS/h = CPM * 0,0098.
I read that there is a pot to increase the voltage of the tube.
Do you think that this would help to increase the sensitivity of the tube?
Or is all right with my GMC?
Thank you for your help guys and sorry for my bad english,
Regards from Germany,
Benedikt |
| 8 L A T E S T R E P L I E S (Newest First) |
| Alchemy2 |
Posted - 05/29/2014 : 12:24:24
I checked the GMC-320 unit I have against a known source with a dosimeter using the same 4011 tube. both read same for me, and my background varies a bit between 10-20 mostly closer to 16-18CPM. I'm fine with mine! |
| ZLM |
Posted - 05/13/2014 : 23:45:02
http://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=3745 |
| Benezi |
Posted - 05/12/2014 : 23:06:42
Where can i find more Informationen about that?
Thanks,
Benedikt |
| ZLM |
Posted - 05/12/2014 : 22:17:12
To get accurate tube voltage reading, you need to serial a 100M resistor and then do a calculation. |
| Benezi |
Posted - 05/12/2014 : 10:45:30
Whats the maximum?
In the Internet it says that I need 380-450V but if i use my Voltmeter it just says between 0 and 200V?
Or can I just use maximum Voltage?
Regards and thank you very much,
Benedikt |
| ZLM |
Posted - 05/12/2014 : 09:15:47
For the GMC-320+, there is a blue potentiometer. Turn it clockwise increases the tube voltage. |
| Benezi |
Posted - 05/12/2014 : 03:17:37
How could I increase the tube voltage?
Regards, Benedikt |
| ZLM |
Posted - 05/11/2014 : 22:01:53
Background 10-15 CPM is normal.
The background CPM may be vary depending on the location. My GMC-320 background is 10-15 CPM too.
Higher CPM background tube does not means sensitive.
increase the tube voltage will increase the sensitivity. But it reduce the tube life. Also, you need to recalibrate the unit.
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