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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
radhoo wrote ...
A geiger tube for liquids, the VAZ431:
More here:
I have a Centronic M2H, which has very similar glass-work, but comes complete with a rubber jacket and an end cap tethered with a short chain, so you can't lose it. I have never had any radioactive liquid to put in it, but it works fine as a general purpose gamma detector. In a dark room, you can see tiny red neon flashes in the tube from background radiation impacts. I guess you could work with these light pulses using a PIN photodiode, and so avoid hanging any coupling capacitance on the circuit.
I couldn't think what number system VAZ431 belonged to, and then I saw 'Dresden' on the label - so East German/DDR. I believe they manufactured some interesting GM tubes. I don't know much about them, but eBay pictures I have seen show good quality modern engineering.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 699
Proud Mary wrote ...
SI-29BG - It's very convenient, being single ended. You could mould a plug onto the end with epoxy, so you would have a plug in tube.
I totally agree! I never knew it was actually so small, until I got the box.. Now I'm looking forward to finishing the PCB for it and see how it performs on the long term.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
radhoo wrote ...
Proud Mary wrote ...
SI-29BG - It's very convenient, being single ended. You could mould a plug onto the end with epoxy, so you would have a plug in tube.
I totally agree! I never knew it was actually so small, until I got the box.. Now I'm looking forward to finishing the PCB for it and see how it performs on the long term.
Single-ended is also good for probe applications - in liquid sampling, for example.
Registered Member #8120
Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94
GMI-90 (ГМИ-90), a pulse modulation tetrode from some sort of a radar. 33KV anode voltage, 40A pulse current, over a megawatt pulse power, 200W of filament heating. All in one of the prettiest tubes out there.
Gold-plated grids inside:
It glows in reds and blues when on, a nice warm sight:
The blue of the plasma is not very visible in the light of the heaters, but with the heat off it is still hot enough to work for some time And there you can see the plasma of the current flowing. Only a few mA, and the colour is hard to get on camera. When pulsed at a few A it lights up in brilliant blue, but it's damn near impossible to capture.
As the cathodes cool down, the plasma becomes purple-red, and much denser:
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What are the most interesting vacuum tubes in your collection?
