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 2.GQ Geiger Muller Counter
 Light Sensitivity of M4011 Tubes (Video)

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ullix Posted - 04/09/2022 : 05:16:54

While I had mentioned it already, I think a video makes a more convincing argument.

Find the video on Youtube

What you see is: A video clip in 3 segments: The first segment shows the tube, and you hear clicks at approx CPM=15. Daylight only, no extra light.

The second segment shows a M4011 tube from 2017 being illuminated with a 405nm (visible light, not UV, of dark-blue color) Laser. It shows a strong light sensitivity, but only at the inner, very end of the cathode. The picture shows that spot on the tube illuminated, which gives highest count rates. Dimensions are difficult to determine, but I guess from gliding with the laser pointer spot over it, its size is not larger than 1 square-millimeter. On the remainder of the tube I do not get any count enhancement at all.

Third segment shows a M4011 tube from 2020. No light sensitivity whatsoever!

It remains a strange effect.

15   L A T E S T    R E P L I E S    (Newest First)
Senketsu Posted - 05/02/2022 : 15:37:01
I have a very powerful UV flashlight so I will check each one.
I also have a 500+ with a GM type M4011 meter painted with black paint and it does not react to UV.

The newer GMC-500 are also devoid of other disadvantages of my older 500 and 500+

1. Displays the voltage of the GM meter (the older ones, even on the same Re 2.29, do not have this option).

2. Image does not rotate by itself in high radiation levels

3. The screen does not turn on the backlight by itself without a reason and pressing a button

I believe that these versions will also not react to UV light, they are already very polished!

Haven't had time to check out the GeigerLog yet
ullix Posted - 05/02/2022 : 01:27:32
Maybe the black foil will finally bring a solution?

With 5 devices in your hand, there is a good chance for testing. Try with a strong white-LED flashlite, and shine along the tubes. In particulat try around the cathode end.

V2.29 seems to be a new firmware. Did you try GeigerLog with the deives? Does all work, or any problems?

Senketsu Posted - 04/29/2022 : 04:55:19
Today I got five GQ GMC-500 and each one already has a black foil inside (at first I thought it was paint). I think I have the latest series (software Re 2.29).

ullix Posted - 04/29/2022 : 00:43:27
@Senketsu: A "GM meter" should be the whole device, the case, the electronics inside, the firmware of the micro-chip, and lastly the Geiger-Müller tube, e.g. a M4011,

Only the tube is sometimes -- not always -- light sensitive.

With respect to "painted black tubes" I actually own a M4011 tube, blackened with some plastic like cover. And: it is also light sensitive! This is reported and referred to several times in this forum. And also in this case, the light sensitivity is only at the very end of the cathode inside(!) the tube. So even this completely(?) blackened tube is light sensitive.

Of course, the very ends of the tube carry the metal sleeves, which must remain uncovered as their electrical conductivity is needed.
Senketsu Posted - 04/28/2022 : 15:23:59
I wonder why the ends of this GM meter are not factory painted black
ullix Posted - 04/12/2022 : 22:29:08
Hi StevenL, yes it is M4011/J305 and it made in China.

I understand this to say that you put either a M4011 or a J305 tube into your counters. And of the J305 tubes there are at least 2 different ones available: a short one and a long one. So it is 1 out of a choice of at least 3.

Given that you have published basically no information on any tube, I suspect you don't know any?

Then, on what grounds to you decide on which tube to use? Is it as plainly as purchase cost?
StevenL Posted - 04/12/2022 : 15:23:21
Originally posted by EmfDev

Tube 2 is SI3BG.

EmfDev Posted - 04/12/2022 : 15:11:02
Tube 2 is SI3BG.
StevenL Posted - 04/12/2022 : 14:34:56
Originally posted by EmfDev

Hi StevenL, yes it is M4011/J305 and it made in China.

Perfect thx. Man, I am so excited to find GQ Electronics!!!

Do you have info on the tube No. 2 (which looks like it has Russianmarkings). Thanks! Steve
EmfDev Posted - 04/12/2022 : 12:43:43
Hi StevenL, yes it is M4011/J305 and it made in China.
StevenL Posted - 04/12/2022 : 12:27:36
Originally posted by EmfDev

We dont know exactly whats wrong but we will check with the manufacturer.

Hi EmfDev, can you confirm that the M4011 is tube no. 1 in the GMC500+? Also, is it made in China? Thx, Steven L.
EmfDev Posted - 04/12/2022 : 09:28:29
We dont know exactly whats wrong but we will check with the manufacturer.
ullix Posted - 04/11/2022 : 22:43:28
@EmfDev: So do I!

I wish I were a commercial purchaser of those tubes, because then I would know who the manufacturer is and I would inquire with the manufacturer about those results!
EmfDev Posted - 04/11/2022 : 10:22:12
I still wonder why it is not consistent with all tubes.
Damien68 Posted - 04/09/2022 : 05:48:38
nice video, it is really in the cap of the end that it is sensitive.

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