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 2.GQ Geiger Muller Counter
 CPM count. Recommendation ?
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GER_aki75

Germany
16 Posts

Posted - 02/14/2019 :  11:57:37  Show Profile  Reply with Quote
Hello,
I have higher CPM readings in my home than I had before. I tested my Geiger counter GMC 320 Plus V4 in an other house where the counting was normal and everything is ok with the Geiger counter.
Here are some screenshots from my measurements:

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What would you recommend ? Should I leave my house or is this usual ?

GMC 320 Plus V4 & GMC Geiger Counter Looger Pro V 5.56
Geigermap Location: 48.348745928343035,10.899212072585215
Reply #1

EmfDev

855 Posts

Posted - 02/14/2019 :  12:46:18  Show Profile  Reply with Quote
Hi Ger_aki75, what was the your previous cpm at home? Did you test for longer time at other places? like 1day or 2?
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Reply #2

GER_aki75

Germany
16 Posts

Posted - 02/14/2019 :  13:25:44  Show Profile  Reply with Quote
Yes I tested several days in an other house and in the other house was no higher count than ca. 65 CPM but only in several single minutes, and the average in the other house was at 38 CPM.
It was about the same CPM readings like in my house before, but the last days and weeks the CPMs are getting higher in my house. I think the Geiger counter is all right.

GMC 320 Plus V4 & GMC Geiger Counter Looger Pro V 5.56
Geigermap Location: 48.348745928343035,10.899212072585215

Edited by - GER_aki75 on 02/14/2019 13:26:32
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Reply #3

EmfDev

855 Posts

Posted - 02/14/2019 :  15:08:47  Show Profile  Reply with Quote
Maybe do more testing in other houses/locations. And then do it again at your house to make sure that the readings are consistent with what you have right now. Otherwise, moving is troublesome.
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Reply #4

GBG12

Canada
59 Posts

Posted - 02/16/2019 :  07:11:00  Show Profile  Reply with Quote
I agree this requires further testing. It's possible Radon gas can leak into hour house from the surrounding earth. Test near a window for a while to get an average, then open the window to let air flow in, then see if the average drops. You can also test on the lowest floor with doors/windows closed compared to open-window values or outside values.
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Reply #5

i80386

13 Posts

Posted - 02/16/2019 :  10:58:40  Show Profile  Reply with Quote
Hello, GER_aki75, 38 cpm on average in the other house also seem as high value, though not as much as yours. In my apartment, I also see higher readings relative to external (~ 27 cpm inside, 22 out), which I think is due to building materials. What is the average CPM value outside the house and a few meters away from other buildings? It's a good idea to do at least a 20-30 minute measurement by restarting the device before the measurement to get average data only for that location.
What is the official statistics for the background radiation in this area?
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Reply #6

GER_aki75

Germany
16 Posts

Posted - 04/22/2019 :  05:54:28  Show Profile  Reply with Quote
quote:
Originally posted by EmfDev

Maybe do more testing in other houses/locations. And then do it again at your house to make sure that the readings are consistent with what you have right now. Otherwise, moving is troublesome.



quote:
Originally posted by GBG12

I agree this requires further testing. It's possible Radon gas can leak into hour house from the surrounding earth. Test near a window for a while to get an average, then open the window to let air flow in, then see if the average drops. You can also test on the lowest floor with doors/windows closed compared to open-window values or outside values.



quote:
Originally posted by i80386

Hello, GER_aki75, 38 cpm on average in the other house also seem as high value, though not as much as yours. In my apartment, I also see higher readings relative to external (~ 27 cpm inside, 22 out), which I think is due to building materials. What is the average CPM value outside the house and a few meters away from other buildings? It's a good idea to do at least a 20-30 minute measurement by restarting the device before the measurement to get average data only for that location.
What is the official statistics for the background radiation in this area?




Hallo,
I was watching my CPM counts the last weeks and month, it is getting higher and higher.
In my house I have average readings up to 200 CPM now all the time.

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And at other places outside the house I get readings up to 1000 CPM, but when I leave this area the Geigercounter gets down to 150 CPM immediately. But temperature seems to be a factor too. I put my Geigercounter in the refrigerator to test that influence, and at 5 Celsius after 15 Minutes it showed 1800 CPM.

So I really dont know what it is. I mean I live in Bavaria and we were really hit by Chernobyl quiet hard (we still cant eat wild boars because of contamination). But I dont think these readings are correct.

But what is frightening me, is that thing with that spots outside where the Geigercounter jumps up to 1000 and higher, but the Geigercounter drops down to 150 and below immediately when I leave the Area or get in a car. This cant be related to the temperature. So I really cant figure out if it is the temperature or something else.


GMC 320 Plus V4 & GMC Geiger Counter Looger Pro V 5.56
Geigermap Location: 48.348745928343035,10.899212072585215

Edited by - GER_aki75 on 04/22/2019 06:52:31
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Reply #7

EmfDev

855 Posts

Posted - 04/22/2019 :  10:25:44  Show Profile  Reply with Quote
Hi GER_aki75, I consulted our engineers and they said there are at least 3 possible reasons:

1. The readings are real. Outside and your refrigerator and your house.
2. The background radiation in your area is higher than usual. So the tube might have reached too many cumulative counts and is close to the end of its lifetime. (might need to replace the tube)
3. There are issues with the tube voltage in the unit.

You might need to buy another device to confirm. Maybe from other brands.
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Reply #8

GBG12

Canada
59 Posts

Posted - 04/22/2019 :  18:27:52  Show Profile  Reply with Quote
Looking at readings from other online counters nearby (Finnig at radmon.org, Augsberg at uradmonitor.com and https://remap.jrc.ec.europa.eu/GammaDoseRates.aspx), your location should not be especially high. Increasing over time indoors, or changing rapidly without apparent reason points more to a tube problem. If it drops rapidly getting into a car, does it also react to light? It shouldn't, but some glass tubes have been shown to do this for unexplained reasons.
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Reply #9

EmfDev

855 Posts

Posted - 04/23/2019 :  09:34:39  Show Profile  Reply with Quote
Yes some tubes react to light. Did you get a black tube?
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Reply #10

GER_aki75

Germany
16 Posts

Posted - 04/24/2019 :  00:20:16  Show Profile  Reply with Quote
quote:
Originally posted by EmfDev

Hi GER_aki75, I consulted our engineers and they said there are at least 3 possible reasons:

1. The readings are real. Outside and your refrigerator and your house.
2. The background radiation in your area is higher than usual. So the tube might have reached too many cumulative counts and is close to the end of its lifetime. (might need to replace the tube)
3. There are issues with the tube voltage in the unit.

You might need to buy another device to confirm. Maybe from other brands.



Thanks for the info. Would you prefer the GMC 500+ over the GMC 320+ if I buy a GQ ?

quote:
Originally posted by GBG12

Looking at readings from other online counters nearby (Finnig at radmon.org, Augsberg at uradmonitor.com and https://remap.jrc.ec.europa.eu/GammaDoseRates.aspx), your location should not be especially high. Increasing over time indoors, or changing rapidly without apparent reason points more to a tube problem. If it drops rapidly getting into a car, does it also react to light? It shouldn't, but some glass tubes have been shown to do this for unexplained reasons.




Ok thanks. Maybe I try to get a new M4011 tube in the internet and try if it helps if I replace the old tube.

quote:
Originally posted by EmfDev

Yes some tubes react to light. Did you get a black tube?



no it is a ordinary glass tube

GMC 320 Plus V4 & GMC Geiger Counter Looger Pro V 5.56
Geigermap Location: 48.348745928343035,10.899212072585215
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Reply #11

ullix

Germany
407 Posts

Posted - 04/24/2019 :  04:52:39  Show Profile  Reply with Quote
I understand you live in Germany. There is simply no place in our country, where you would measure even CPM 54, let alone any of the higher values. See here for official data:
http://odlinfo.bfs.de/DE/themen/wo-stehen-die-sonden/messstellen-in-deutschland.html

So something is wrong with your counter, either the electronic, or the tube, or both.

The tube being defect is a good guess. Though before I'd replace it, verify the voltage at the tube. Make yourself aware of the technical issue you face measuring a high impedance circuitry with a lower impedance volt meter. This topic may be a good start:
http://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=3745

If you are measuring anything different from the range 120...150V when using a regulat 10MOhm Multimeter, the voltage setting is wrong.

If you are within that range, testing a different tube will tell you if it's the tube or something beyond. In the latter case, a repair at GQ will be needed.

Edited by - ullix on 04/24/2019 04:54:08
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Reply #12

GER_aki75

Germany
16 Posts

Posted - 04/24/2019 :  13:05:34  Show Profile  Reply with Quote
quote:
Originally posted by ullix

I understand you live in Germany. There is simply no place in our country, where you would measure even CPM 54, let alone any of the higher values. See here for official data:
h**p://odlinfo.bfs.de/DE/themen/wo-stehen-die-sonden/messstellen-in-deutschland.html



I dont think of a natural source or something like Fukushima or something, but there is a dentist in my house for example and dentists have x-ray devices. So I am "more afraid" of a artificial source in this context.


quote:
Originally posted by ullix

So something is wrong with your counter, either the electronic, or the tube, or both.




meanwhile I came to this solution too, but when it started in my house, other location had still low readings, so I didnt think that my device was broken or something

GMC 320 Plus V4 & GMC Geiger Counter Looger Pro V 5.56
Geigermap Location: 48.348745928343035,10.899212072585215
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Reply #13

EmfDev

855 Posts

Posted - 04/24/2019 :  14:02:50  Show Profile  Reply with Quote
I'd recommend the 500+. Since its m4011 tube (glass tube in 320+) is made of black glass not transparent. And it has more features.
But I think I'd prefer you buy from other trusted brands if you want to confirm the readings are true.

Yes you can also do the tube replacement since it's cheaper. If you know how to measure the voltage between the tube, you can also verify if it's in the working voltage. You can adjust it if necessary. There is a potentiometer that can be adjusted on the PCB.

Edited by - EmfDev on 04/24/2019 14:04:13
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Reply #14

GER_aki75

Germany
16 Posts

Posted - 05/06/2019 :  06:37:15  Show Profile  Reply with Quote
Ok, I think it was the potentiometer. I adjusted it with a multimeter to ca. 130-135 Volt like User Ullix recommended and the readings are back in the normal area again. Maybe the microvibrations from having the Geiger counter in my pocket for transport changed the potentiometer setting.
And the tube seems to be light sensitive.
Thanks for the help

GMC 320 Plus V4 & GMC Geiger Counter Looger Pro V 5.56
Geigermap Location: 48.348745928343035,10.899212072585215

Edited by - GER_aki75 on 05/06/2019 06:37:44
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