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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I bought a G-M tube type CV2886 from an ebay seller for £5, without data of any kind.
It is a glass tube in an armoured rubber jacket, with an end cap secured to the body with a keeper chain, so I would guess it to be a beta-gamma type, perhaps designed to have liquids poured into it.
It is identical to the one pictured here:
Vt is noted on the label in indian ink as 350V. I have it running on a test rig on the bench right now - the 350V coming from a Bertan 313A variable PSU, to the usual voltage divider in the anode circuit (20M and 2M7) with 40pf silver mica taking the signal to a MC34119P IC audio amp lash-up on a bread board.
It is popping away at about 40 cpm from the background - though perhaps half of that is the tube's own intrinsic activity as is often the way with more sensitive types
An oddity: with the room lights off, small mauve or purple flashes are visible in the tube with each event, so I suppose it must have neon in it,
Does anyone have any further data about this tube that they could share with me please?
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
No real data on this tube I`m afaraid, except that it is vintage (1950`s), and of UK origin. Valves and tubes bearing the CV numbers are ex MOD, and are difficult to find data for.
I`m guessing that the base of the tube looks something like this:
o)| o
2 pins seperated by a bakelite `key`?
If so, it will almost certainly fit the 1950s MOD geiger counter: `Indicating Unit No. 6665-110118`
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Yes, Sulaiman, although the tube is obviously quite ancient - from the 1950s I'd guess from the antique handwritten label - the relatively low working voltage suggests it has a halogen quench gas, such as bromine rather than ethanol or butane and so on, which you find used as quench in some ancient tubes with working voltages of 1kV or so.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
plazmatron wrote ...
No real data on this tube I`m afaraid, except that it is vintage (1950`s), and of UK origin. Valves and tubes bearing the CV numbers are ex MOD, and are difficult to find data for.
I`m guessing that the base of the tube looks something like this:
o)| o
2 pins seperated by a bakelite `key`?
It is just that sort of socket, and I have it set up in one, though I can't for the life of me remember what it is called.
My other glass tubes - B12N, B12H, and B6H - all have international octal bases, which are easily found, and in porcelain too. The 2-pin base I am using with the CV2886 test rig originally came with a Mullard MX168 [Centronic ZP1481] which I bought on ebay.
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G-M Tube CV2886
