SBT-10 Geiger Tube

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5 years 3 months ago - 5 years 3 months ago #3082 by stdorn01
SBT-10 Geiger Tube was created by stdorn01
Does anyone have experience with the sbt-10 geiger tube. I was wondering if anyone has any idea what would cause black spots on the mica where it touches the metal inside the tube. I just received a SBT-10 and did not notice any spots on it but noticed them after running it awhile. I may have initially overlooked the spots as I was in poorly lit room and was anxious to get it wired up and test it. I did a web serarch and the only info I found on black spots was a SBT-10 for sale on ebay with black spots on it. I would like more info on this if anyone has/knows anything. Pic included.

Steve



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Last edit: 5 years 3 months ago by stdorn01.

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5 years 3 months ago - 6 months 3 weeks ago #3084 by Simomax
Replied by Simomax on topic SBM-10 Geiger Tube
Hi Steve,

I believe you have the model incorrect and is a SBT-10 or SBT-10A. Some info here: www.pocketmagic.net/tube-sbt-10a-c%D0%B1t-10a/

I too have recently bought one of these from a seller in Ukraine. Mine too has the black spots similar to yours (see below). The seller assured me mine was NOS (new-old-stock), meaning whilst it is old, it has merely been stored for the time and never used. Mine appears to be working correctly regardless of it's condition. I tested each element seperatly and each reads around the same CPM as the others so I'm assuming that whilst cosmetically nasty, the black spots appear to do no harm. What causes them I'm unsure of, but I suspect it is some kind of age related issue. Possibly some kind of reaction between the materials and the gasses used in constructing these tubes. I wish I could help you more. I too would like to know what the spots are and if they are impacting the reliability of the tube.

 

On a side note, I have found a person in Lithuania that supplies a 3D printed connector with pins or just the pins themselves here: arduino-geiger-pcb.blogspot.co.uk/2015/0...t-for-sbt-10-10.html
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Last edit: 6 months 3 weeks ago by Simomax.
The following user(s) said Thank You: Gamma-Man, stdorn01

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5 years 3 months ago #3085 by stdorn01
Replied by stdorn01 on topic SBM-10 Geiger Tube
thanks for the info. I don't know why I was thinking sbm. Anyway I fixed it now.

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6 months 3 weeks ago #5881 by Simomax
Replied by Simomax on topic SBM-10 Geiger Tube
I sort of know what the black spots are now. They are some kind of crystaline chemical or mineral that is growing on the surface of the mica.

I put my SBT-10A under my stereo microscope a few weeks ago (before I had a camera for my microscopes) and could see they were hexagonal in shape. Some were like triangles with their points cut off. They appear as arbitrary shapes and almost like little blobs and that is because some grow next to others and some grow on top of others. They appear to be very very thin, although there were a couple that I could just see had a little more length to them. I think they are being caused by some chemical in the resin leaching out and reforming as crystals.

I thought I would follow up with some microscope images of them, but I managed to destroy my tube by accident by dropping a polarizing filter from my microscope onto the tube.   So that's the second SBT-10A that has broken on me. 

Oh well, at least we can see inside one now! I'll do a separate post on that.

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