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Sallet
United Kingdom
16 Posts |
 Posted - 04/12/2012 : 08:10:11
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I have fitted a SBT-9 tube to my GMC-300 and it detects alpha from my Am241 source very well, so well in fact that it gets above 32,000 CPM and then a minus sign (-) appears in front of the count and it stops rising and starts counting back down. When I remove the source, the negative number starts counting back up to about -32,000 again after which the minus sign disappears and the CPM drops slowly from 32,000 down to about 20-25 CPM at background! A bit strange!
I realise that (hopefully) one would never experience this sort of level in the environment but it does mean it is not possible to get a proper reading above this 32,000 level. I also notice the speaker gives up above about 10k.
Finally, each time I repeated this experiment , I got an isolated pulse of about 200 CPM about 30 seconds after it returned to stable background count. It did this after each high count test but is only seen once after each test.
I have reduced the voltage for this tube to its lowest level setting and still find the machine is very sensitive with the SBT-9.
Is this a firmware issue? Any opinions would be welcome! |
Nick |
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| Reply #1
RCB
1 Posts |
Posted - 04/13/2012 : 15:32:53
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| I am also getting elevated levels with the GMC-200 from 584.2 to 835.4 CPM just from background noise, but the graph seems to register nothing much above 20, I'm completely confused, does 585-835 CPM really mean 58.5 to 83.5 CPM? I am located in Utah at an elevation of around 4000 feet. |
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| Reply #2
ZLM
1261 Posts |
Posted - 04/13/2012 : 23:11:14
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The minus sign (-) is the old firmware issue. It is limited to 3200 CPM reading.
Check your firmware version. The newer GMC-300 firmware version should have upper limit of 65535 CPM. |
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| Reply #3
ZLM
1261 Posts |
Posted - 04/13/2012 : 23:12:55
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For the GMC-200, there are must be something wrong with the reading. the CPM should not have < 1 part.
The CPM is CPM. |
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| Reply #4
Sallet
United Kingdom
16 Posts |
Posted - 04/14/2012 : 01:25:07
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Hi, I have firmware revision 2.11 and have only had the machine about 2 months. I can't see where to download a newer version or how to update it. Which is the latest firmware and can you advise me?
Nick |
Nick |
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| Reply #5
Sallet
United Kingdom
16 Posts |
Posted - 04/16/2012 : 13:55:53
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Hi ZLM, sorry to ask again but is there a newer version of firmware than 2.11 and how can I update it?
Thanks |
Nick |
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| Reply #6
ZLM
1261 Posts |
Posted - 04/16/2012 : 20:24:57
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Yes. There is newer version firmware. Unfortunately, user is unable to update the firmware. The unit need to be sent back for upgrading.
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| Reply #7
Sallet
United Kingdom
16 Posts |
Posted - 04/17/2012 : 11:29:11
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Ok, but i have some questions.
Can this be sent back under warranty or do I have to pay for this? It's only about 2months old.
Do I have to pay postage in both directions?
As I currently have the SBT-9 installed, should I replace it with the supplied tube?
Does this affect warranty as I had to make a small hole in the case to allow alpha particles to reach the mica window?
Finally, what enhancements are in the new firmware?
Thanks for your help!
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Nick |
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| Reply #8
brianweber4
USA
10 Posts |
Posted - 04/17/2012 : 15:47:06
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| please post some pictures of your SBT-9 modified geiger counter! also are you using 10 megohms for the anode resister? I believe that that is the value needed. |
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| Reply #9
ZLM
1261 Posts |
Posted - 04/17/2012 : 20:40:11
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Yes. Your GMC-300 is still under warranty if you only changed the tube.
The upgrading firmware is free, you only need to pay the shipping.
You do not need to change back the original tube. You can send it with the SBT-9 tube.
Yes. You need to pay the both direction shipping.
The latest firmware changed followings:
1. adjusted the default calibration data. So that to get more accurate estimate on uSv/h and mR/h dose.
2. fixed some other small firmware bugs.
3. extended upper limit CPM to 65535.
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| Reply #10
Sallet
United Kingdom
16 Posts |
Posted - 04/18/2012 : 05:30:54
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Thank you for the information!
Do I post it to the address on the Home page?
I can deal with the postage from this end but how much and how do I send return postage payment? By PayPal ? Will you request money by PayPal when it ready to send back to me?
Finally, how long will it take? |
Nick |
Edited by - Sallet on 04/18/2012 05:34:37 |
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| Reply #11
ZLM
1261 Posts |
Posted - 04/18/2012 : 10:05:08
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please write to support@gqelectronicsllc.com for a RMA code.
The return postage you need to pay before send it back to you only. |
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Topic |
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High counts on GMC-300?
