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tcp100
2 Posts |
 Posted - 08/03/2017 : 10:56:20
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So I just received my GMC-320+ v5 yesterday. I tried it for about 5-10 minutes at a time around the house, and everything seemed normal - background radiation showing 20-30 CPM.
So today I decided to take it on my commute to work, which happens to go past Rocky Flats in Colorado - a known site with issues. Strangely enough as I drove by there, the readings were actually very low - about 15-20 CPM.
However, about 30 minutes into my commute, right as I reached Golden, CO, the numbers started continuously climbing.. First 60 CPM, then it hit 100. It all started as I got near a Starbucks in Golden, where I ordered a coffee at the drive through..
By the time I got to my office in Evergreen, CO, the GMC-320 was reading 1500 CPM! I honestly thought that Starbucks had handed me a nuclear coffee..
It didn't matter where I went with the GMC-320, it would read insane readings.. inside the car, left on the ground across the parking lot as I walked away from it.
I have it on my desk in my office now, and I left it powered down for 30 minutes. It's now reading fairly normal when first turned on, but then starts climbing after about 5 minutes of being powered on. About 70 CPM after 5 minutes, 100 CPM after 6-7 minutes.. then it starts to climb almost exponentially, hitting 1500 CPM after about 10 minutes of being on.
Is this a defect, or do I need to call the authorities? :) Kinda sorta kidding. |
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| Reply #1
tcp100
2 Posts |
Posted - 08/03/2017 : 11:17:57
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Just wanted to add, it seems to be related to how long the unit is on.
If I power it off and right back on, it jumps immediately to 200-300 CPM and keeps climbing.
If I leave it off for a while, the climb is much slower.
EDIT: If I blow on the tube through the vents, the count drops immediately and precipitously.. Like from 1400 CPM right down to a normal 30 CPM, within the course of a minute. Then it starts to climb again.
I saw someone mention this in another post, but I'm not sure what it means - the tube overheating? Overall this behavior seems overheat-related to me, and indicates a defect in the tube. Does this sound right? |
Edited by - tcp100 on 08/03/2017 11:38:33 |
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| Reply #2
ChrisLX200
United Kingdom
35 Posts |
Posted - 08/04/2017 : 00:17:49
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| If it's getting hot then there must be a high resistance, try re-seating the tube in its clips because perhaps they have oxidised a little. Power the device off first - don't touch the clips when it is running! (high voltage, and beware the caps may hold voltage for a long time even after powered off). |
GMC-300E-plus |
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| Reply #3
the_mike
Switzerland
53 Posts |
Posted - 08/04/2017 : 04:35:10
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Hey tcp100
Try to open the (turned off) device, and check if the tube is mounted correctly (there's a + - sign on the tube, it should match the to the plus-pole on the board... (attached a photo of my 320v4; the plus-pole (indicated by a picon) is on the left
(if you have to turn the tube, don't touch it with your fingers, wear some gloves)
If this is correct, i suspect the tube is getting too many volts - this would be a task for the support@gqelectronicsllc.com
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Edited by - the_mike on 08/04/2017 04:37:49 |
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| Reply #4
ZLM
1261 Posts |
Posted - 08/04/2017 : 22:09:45
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The unit seems need a new tube. The tube may be leaking.
You can write an email to support@gqelectronicsllc.com for the warranty.
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| Reply #5
Distelzombie
Germany
202 Posts |
Posted - 08/04/2017 : 23:41:37
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The high voltage on this device is not harmful. It's a little device with a small battery that runs for month. There is so little amperage that you don't even feel anything.
It's not volts that kill. |
GMC-300E+ V4.20 with sbt-11a alpha tube
My statements are "stuff-a-hobbyist-says" and not in any way professional. |
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Normal readings for 30 mins, then off the chart..
