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paul
United Kingdom
54 Posts |
 Posted - 05/25/2019 : 07:48:47
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I'm curious as to why I am reading such high background levels.
I have a new 600+ with a LND 7317 tube, Rev. is 2.07
I'm staying on the west coast of Scotland at the moment.
You can see the "72" on your map,data is open to read.
My readings seem to be 2 or 3 times higher than most others.
I checked the village and it fluctuates from 30 to 85.
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| Reply #1
ZLM
1261 Posts |
Posted - 05/25/2019 : 21:30:34
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Different tube should have different CPM reading on same level of radiation. The LND 7317 is a high sensitive tube. The CPM reading should be 2-3 time higher than M4011 tube.
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| Reply #2
paul
United Kingdom
54 Posts |
Posted - 05/30/2019 : 09:05:13
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More observations than questions,perhaps the community wish to comment.
I still find my readings in uSv/h ,50% to 100% or more,higher than the
readings of the official EU monitoring sites ,available here -
h**ps://remap.jrc.ec.europa.eu/GammaDoseRates.aspx
The nearest EU reading stations are at least 50 miles away ,North,East
and South over rugged terrain.West is in the Atlantic ocean.
This area is on the edge of a relatively high Radon area,map here -
h**ps://www.ukradon.org/information/ukmaps
My 600+ LND 7317 also seems to be a lot more sensitive than the official
readings on the graphs at the first link,which vary little over time.
My readings vary a lot over time,as my GQ map data shows.
Are the EU official readings to be trusted ?
(Are any officials to be trusted ?)
Online,various commentators express doubt as to the accuracy of
Japanese official readings.
Perhaps the Japanese officials are wishing not to spook the herd.
GQ map readings show surprisingly low readings in Japan,although there
are few counters,and none close to Fukushima prefecture.
I understand,after reading the excellent work of stargazer 40 and ikerrg at
this amazing thread -
https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=5554
that this is a complex field of research,and no longer expect straight definitive
answers.
It is not even clear exactly what I am measuring.
Background indeed. |
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| Reply #3
EmfDev
2250 Posts |
Posted - 05/30/2019 : 12:31:50
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| We don't really know why readings from government or official readings are lower. They're usually lower in most countries compared to readings from the public. |
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| Reply #4
paul
United Kingdom
54 Posts |
Posted - 05/30/2019 : 13:17:24
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| As I said,don't spook the herd. |
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| Reply #5
ullix
Germany
1171 Posts |
Posted - 06/04/2019 : 01:21:14
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@paul:
given what kamilw has found, and what I have basically confirmed, here http://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=7149
can you take a look around your counter and check for any possible sources for interference?
Sources could be: phones, WiFi, router,radio, elevators, air conditioning, microwave ovens, workshop equipment, etc, etc!
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| Reply #6
paul
United Kingdom
54 Posts |
Posted - 06/04/2019 : 10:17:15
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Yes,I saw with interest kamilw's post.
And I have discovered under floor wiring that does have
RF spikes on it,which I can see with my EMF390.
So I have put my 600+ on the floor in a space that has no
RF according to the EMF390,and have put it on the Map just now.
First 5 minuets it looks the same,0.200 uSv/h already.
II'l leave it on for a while,lets see. |
Edited by - paul on 06/04/2019 15:23:55 |
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| Reply #7
paul
United Kingdom
54 Posts |
Posted - 06/04/2019 : 12:00:11
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That's well over an hour and my readings are the same.
I don't think my device is reacting to stray EMF.
Its in a cold spot,no Voltage,RF,mG,nothing.
I think its working OK.
Just a sensitive tube in a slightly higher Radiation zone I guess.
Glad I bought it. |
Edited by - paul on 06/04/2019 12:32:33 |
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| Reply #8
bc10
8 Posts |
Posted - 08/14/2019 : 12:48:18
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If the high reading is not because of your actual environment, is it possible your device is contaminated somehow?
Perhaps cleaning the surface may help? I'd probably prefer to clean the detector's mica window too but I'd be afraid of damaging it.
I just got my GMC 600+ and the first thing I did was tape up the openings of the new device including the detector opening so dust particles can't contaminate it over time when not actively attempting to measure alpha readings.
My background is high too. 50 CPM indoors, but works out to be within range of annual dosage for my area provided the Raw-to-dose conversion factor is correct. Currently my CPM to uSv/h conversion factor is set at 350 from the factory. I don't have a calibration source to test, tune and verify accuracy of the conversion readings though. |
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| Reply #9
EmfDev
2250 Posts |
Posted - 08/14/2019 : 13:04:32
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| bc10, you might be blocking the alpha particles by taping your device. |
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| Reply #10
bc10
8 Posts |
Posted - 08/14/2019 : 13:22:07
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quote:
Originally posted by EmfDev
bc10, you might be blocking the alpha particles by taping your device.
Yeah I know. I am using it for environmental monitoring so it's ok to just detect beta + gamma. I was gonna buy the cheaper GMC500+ but decided to go for the better GMC600+ which detects alpha too and an added bonus.
I'll expose the detector again if there was a desire to measure alpha. Otherwise I like the idea of keeping the internals clean so I can wipe down the surface if need be.
My nightmare scenario is if some dust contaminated the detector over time, which will ramp up the background measurement over time due to the contamination's constant contribution to the CPM. |
Edited by - bc10 on 08/14/2019 13:24:21 |
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| Reply #11
EmfDev
2250 Posts |
Posted - 08/14/2019 : 13:31:57
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| I see, it's good keeping it clean. However if you think the CPM has increased, then you can still change the CPM to uSv/h conversion on the unit. |
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| Reply #12
paul
United Kingdom
54 Posts |
Posted - 08/14/2019 : 13:52:48
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bc10 (If the high reading is not because of your actual environment)
Actually I think the high reading IS because of the environment.
The Radon map link above shows that I am on the edge of an area of
slightly elevated Radon gas levels.
Contamination is unlikely.
The device is relatively new and is used indoors.
Mainly it is kept in the bag.
I would leave it on more,but I've read that the tubes wear out over time
I would rather keep it for when it may be needed..... |
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| Reply #13
cypher
USA
10 Posts |
Posted - 05/09/2020 : 03:04:39
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| I I have a 600+, I run it 24/7 I keep it indoors. I didn’t know the baggy thing. Is it. Good idea to keep it in the baggy? |
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| Reply #14
paul
United Kingdom
54 Posts |
Posted - 05/09/2020 : 11:29:26
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| Probably not if it is ON. |
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Topic |
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High Background
