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Pcriged
USA
10 Posts |
 Posted - 10/16/2021 : 16:50:21
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What's the default tube voltage for the Gmc-600+. Mine came from the factory set for like 570v and it caused the unit to "runaway" lock up and give unrealistic readings untill rebooted. Started playing with setting and noticed the voltage was cranked set voltage to 400v is this recommended? It solved my issues but not sure how that effects the sensitivity?
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Ethan |
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GBG12
Canada
101 Posts |
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Damien68
France
780 Posts |
Posted - 10/17/2021 : 02:11:54
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inside the GMC-600 +, there is a tube LND7317, in principle it works from 475v to 675v
https://www.lndinc.com/products/geiger-mueller-tubes/7317/
the best is to keep the factory settings or to do a factory reset if you have modified them because the voltages indicated by the GMC-600+ are not very precise.
if you have a too low voltage (under 475v), the tube no longer detects particles in the right way,
if you have a too high voltage (over 675v), parasitic avalanche phenomena will occur in the tube and it will cause a lot of falses detections.
between these two values you are on the geiger plateau
https://en.wikipedia.org/wiki/Geiger%E2%80%93M%C3%BCller_tube
if you have incorrect measurements with the factory settings, take measurements outside to check that it is not due to contamination in your home
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Mastery is acquired by studying, with it everything becomes simple |
Edited by - Damien68 on 10/17/2021 02:16:15 |
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Pcriged
USA
10 Posts |
Posted - 10/17/2021 : 06:25:59
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| I'm having a different issue. The counter hits 20k or so counts and the counts countinue to go up after the source is removed. The counts go up 100x what the source is rated for and will not return untill the unit is powered off. The speaker also goes out too and the light stays steady red. I feel the unit may be defective. |
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Damien68
France
780 Posts |
Posted - 10/17/2021 : 07:01:19
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| maybe it's only a software version problem, it's EmfDev from GQ who can tell you more on Monday. |
Mastery is acquired by studying, with it everything becomes simple |
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Pcriged
USA
10 Posts |
Posted - 10/17/2021 : 08:19:10
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| Sounds good as I would rather not exchange the unit as I have a started a long term survey tuned to this unit so all the tube settings need to stay the same as well. I just reset the device again so setting are back to default and the error is still present. |
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EmfDev
2250 Posts |
Posted - 10/18/2021 : 10:03:58
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| It takes about 1 minute to get to lower readings after exposing the device to high radiation unless you are using fast estimate time. |
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Pcriged
USA
10 Posts |
Posted - 10/18/2021 : 13:05:27
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| @emfdev it's not that the fast estimate is taking to long too to adjust it's becoming overloaded. I can also hear what I assume is the high frequency high voltage generator struggling to keep up. The voltage display shows an increasing percentage up to 100% and an eventual voltage drop to ~489v. I have some prior experience with Tesla coils and it seems like a voltage leak. I'm making a huge assumption here but it seems like the tube may be allowing a permanent arc instead of the regular pulses. I could certainly be incorrect but I am certain that regular operation should not jump to several hundred thousand cpm from a regular cheep NORM test sample. 2.2k on a gq gmc-500plus. Until recently I've previously noted ~20k activity with the 600+ so while it's a pretty hot sample it's not going to break a tube. |
Edited by - Pcriged on 10/18/2021 13:51:29 |
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Pcriged
USA
10 Posts |
Posted - 10/18/2021 : 14:00:03
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| I figured why explain it if I can show you. https://youtu.be/S4oZpYgNcpg If I could draw your attention to a specific point when normal operation ceases and the malfunction starts, you will notice a change in sound and the led goes solid. Apologies for my background noise. |
Edited by - Pcriged on 10/18/2021 14:07:08 |
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EmfDev
2250 Posts |
Posted - 10/18/2021 : 14:48:41
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| There maybe is a noise caused by the high voltage circuit (maybe EF). Do you want to test a firmware with no auto voltage feature? If yes please email me your serial number and I can generate a firmware for your device. |
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Pcriged
USA
10 Posts |
Posted - 10/18/2021 : 15:25:26
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| Thank you for the prompt support Email sent. |
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| Reply #11
EmfDev
2250 Posts |
Posted - 11/08/2021 : 17:23:14
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| We have received the device and our engineers tested it and it was a tube issue. |
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Pcriged
USA
10 Posts |
Posted - 11/09/2021 : 15:44:35
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I suspected as much. I love electronics <3. Did they specifically say what was defective about the tube? I'm seriously curious about weather it was a runaway high voltage cascade. If you happen upon the information I would love to know. Also if you ever want to have someone test any alternative tubes in a 500+ or 600+ unit please contact me as I have a growing number of Geiger and scintillation units and will most likely be adding custom tubes to my 500+ workhorse pending a verification that this wouldn't void the remaining warranty.
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EmfDev
2250 Posts |
Posted - 11/09/2021 : 16:41:25
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| The test done was to simply take a new working unit which passed the test of high CPM (not cascading with pulses). Then swap the tubes. The one with defective tube still didn't pass the high cpm test that is why it was a tube issue and not the voltage or the main board. |
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| Reply #14
Damien68
France
780 Posts |
Posted - 11/09/2021 : 23:46:21
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certainly the gas from the tube was badly purged during its manufacture, or else the tube is not completely airtight and air has entered into it. normally in the tube there should only be alogen gases.
I have already seen exactly the same problem (detection burst around 1000 CPS or more from time to time) after having tinkered with an old SBM-20 tube to transform it into SBM-20-1 (ie remove the two end caps) when of my first attempt I corrupted the tube and let in a little air.
my second attempt was good, it still runs 24 hours a day. |
Mastery is acquired by studying, with it everything becomes simple |
Edited by - Damien68 on 11/10/2021 00:13:35 |
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600plus voltage
