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Dascha
Switzerland
2 Posts |
 Posted - 11/21/2025 : 00:42:46
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Hello,
I have a GMC 320 that I wanted to take to my trip to Japan to check levels in Nagasaki. My trip was on a cruise ship. Out of fun I tried it on the Pacific ocean, but it scared the hell out of me.
Between Los Angeles and Hawai, the meter went crazy.
So my question: Does the counter work properly on the sea with high humidity. Or does the salt in the air alter the measurements?
Also, the meter starts counting upwards until around 63 and then it jumps to 280. During 2 days in the Pacific, by measuring on the balcony of my cabin, it even went up to 12234 cpm.
In Nagasaki it "only" measured around 3000 cpm.
Thank you for your feedback. Anybody experienced something similar?
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Dascha P. |
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| Reply #1
ullix
Germany
1235 Posts |
Posted - 11/21/2025 : 01:33:14
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Oh, they forgot to tell you the ship has a nuclear reactor? ;-)
I had been out on the ocean on a little sailboat, and the background you measure is typically less of what you get over land, because there isn't all this radiating stuff from soil. Most of that is K-40, perhaps some Uranium and its daughters.
First step to take: search in the counter's menu whether it has a "FET" setting, and switch it Off. It is Off when set to 60 (sec). Please, also look up what firmware version your device has, and post it.
My guess is you should see an average of CPM=10...15 when on the balcony, and even less when inside, because of shielding from cosmic rays by the big iron around you.
If FET is off and you still see such monster readings your counter is defect and needs service.
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| Reply #2
Dascha
Switzerland
2 Posts |
Posted - 11/26/2025 : 01:36:31
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Hi, thanks for your answer. Your are right, I am a russian spy and was on a nuclear ship. Ahaha..
The counter doesn't have a FET setting (or I didn't find it). The model I have is a GMC-320 Plus, +V4 (whatever that means). Revision 4.25, Serial F488017A82F13A. That is all the information I can find on the device.
At home the device seems to be working fine ( around 19-25 CPM).
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Dascha P. |
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| Reply #3
ullix
Germany
1235 Posts |
Posted - 11/27/2025 : 02:57:19
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According to my docs this model does indeed NOT have a FET setting, which is a good thing!
So, the puzzle remains, where do these very high counts come from.
Your land counts are a weeny touch on the high side, but higher altitude plus lots of granite around you might explain that. So far looks ok.
On the ship it could be electromagnetic interference (elevators, ...). Try wrapping the counter fully in aluminum foil. Any improvement?
But you also saw too high counts in Nagasaki - to be sure: away from ship and marina? Not likely to also be due to EMF.
Open the counter's back. Anything unusual? Any whitish powder (like salt)? Wiggle the tube in its sockets, perhaps it has bad contact?
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| Reply #4
EmfDev
2369 Posts |
Posted - 11/28/2025 : 18:02:17
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Another possibility is UV light sensitivity from the sun when you are measuring outside. Did you happen to place the device directly under the sunlight?
If it is light sensitivity, you can put a black shrink wrap around the tube to shield it from UV light.
Your device seems to be an older version and the tube may be at the end of its lifetime. |
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| Reply #5
ihab17
Italy
237 Posts |
Posted - 12/01/2025 : 02:20:12
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quote:
Originally posted by Dascha
Hi, thanks for your answer. Your are right, I am a russian spy and was on a nuclear ship. Ahaha..
The counter doesn't have a FET setting (or I didn't find it). The model I have is a GMC-320 Plus, +V4 (whatever that means). Revision 4.25, Serial F488017A82F13A. That is all the information I can find on the device.
At home the device seems to be working fine ( around 19-25 CPM).
I have few questions for you.
1: When you took those counts where was the counter positioned?
2: If you move the counter to a different location and in contact with different material, did the reading remain the same or it changed?
3: Are you sure you did not have a radioactive source near the counter?
4: I see the counter against a gray (chair?), what is this? Did you move the counter somewhere else and then take different readings?
5: Why is the counter reporting Feb 14 2024?
6: When was the last time you used the counter and which matter/material did you check?
7: Are you sure you did not touch/deal with radioactive material on this ship?
The number does not make sense if none of the above it true |
Edited by - ihab17 on 12/01/2025 02:22:08 |
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Readings on ships
