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What are the most interesting vacuum tubes in your collection?

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Marko

Wed Dec 21 2011, 11:52PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

GMI-32b: Pulse tetrode, Pa 2kW, Vap 40kV, Iap 100A, cooling: forced air, indirect heating. With cooling "chimney".

Woah Jan, where do you get this kind of stuff? For some of my newest and most evil plans, I'd almost give a leg for one...

Marko

Dr. Dark Current

Tue Jan 10 2012, 11:25AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

SRS 326: Power triode, 250 watt plate dissipation.

Proud Mary

Sun Jan 15 2012, 03:10PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Centronic B12H glass beta-gamma GM detector

1326661602 543 FT0 Centronic B12h C Second Go

The tube with the clear glass was manufactured when Centronic was still called 20th Century Electronics. It can only be used in darkness, as UV photons will cause erratic firing, but it is ideal for measurement immersed in fluids.

The later version of B12H produced under the Centronic brand has an opaque coating, but even this thin layer causes some loss of beta sensitivity.

Both types have an International Octal 8-pin base.

1326639028 543 FT0 Centronic Glass Gm Tubes

I understand Centronic recently stopped supplying B12H, but its 50 year track record gives some idea of the the quality and usefulness of this outstanding detector.

EDIT: Whoops, I may have got that one wrong! B12H is still in the Centronic catalogue of standard detectors, though now with a nifty bright blue base, an old horse shod with new shoes. It is the similar, but higher voltage, B12N glass beta-gamma detector that has been phased out.

Proud Mary

Tue Jan 17 2012, 02:01PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Here is a B12N, which I refer to in the post above...

Centronic B12N beta-gamma GM detector

B12N is very slightly less sensitive than B12H, operates best at 675V, and its cathode is a conductive film deposited on the inside of the glass. The flash has made this fluoresce, so it is more apparent here than to the naked eye in natural daylight.

B12N uses Ne/halogen fill gas, and its LND near equivalent is 72514

Proud Mary

Thu Jan 19 2012, 09:12PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Centronics M2H (UK MOD CV2886) glass beta-gamma detector for sampling liquids
Another member of the Centronics glass beta-gamma detector family

This rubbery old horror was designed as an accessory for Meter, Contamination, No. 1 set, in 1953, so it's a bit of a surprise to find it still in the Centronics product guide.

M2H was intended for liquid sampling in Cold War doomsday applications. The end cap was removed while worried soldiers dribbled the suspect liquid into the space between the clear plastic container and the glass tube.

The base plugs into the ancient and absurdly expensive B2 (British 2-pin) socket, still widely used for GM tubes, whilst long obsolete everywhere else.

In the open end view below we can see the helical structure of the M2H cathode - as with B12H above - perhaps explaining the 'H' suffix. It looks as if it would be impossible to thoroughly decontaminate the sampling chamber after exposure to the highly radioactive liquids consequent upon a 1950s "A-bomb" blast, a shortcoming which also limits the use of M2H for accurate scientific work.

Of course, when using M2H as a general purpose gamma-only detector, there's no reason at all to remove the rubber cap.

1327006206 543 FT0 Cv2886 Interior End View Cap Off

The fill gas is Ne/Br, and when viewed in darkness, flashes of reddish light can be seen with each Townsend avalanche - an opportunity perhaps to take off the signal with a PIN photodiode, when good use could be made of the opaque black rubber jacket to exclude all ambient liqht.

radhoo

Thu Jan 26 2012, 05:14PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

A huge GM tube, containing 10 detectors and a mica window, here is the russian SBT-10A . The A model comes with several improvements over the original non-A design.

The tube runs at 390 V. Datasheet here:

radhoo

Thu Jan 26 2012, 05:41PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Here are three VFD tubes (Vacuum fluorescent display),

Some details here:

Proud Mary

Thu Jan 26 2012, 09:32PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

radhoo wrote ...

A huge GM tube, containing 10 detectors and a mica window, here is the russian SBT-10A . The A model comes with several improvements over the original non-A design.

The tube runs at 390 V. Datasheet here:

What a wonderful device! You can switch from coincidence to anti-coincidence counting, run both modes at the same time, or just run the ten devices in parallel to increase the aperture or capture area. ! I've heard about these but never seen one before. Thank you for posting it!

1n5ane

Tue Feb 07 2012, 10:36PM

Registered Member #3283 Joined: Wed Oct 06 2010, 11:03PM
Location: Toronto, Canada
Posts: 29

Here's part of my power tube collection:

4-1000A: Transmitter tetrode, Pa=1kW
DSCN0003

4-250A: Transmitter tetrode, Pa=250W
DSCN0004

4-125A: Transmitter tetrode, Pa=125W
DSCN0005

4-65A: Transmitter tetrode, Pa=65W
DSCN0006

Family photo:
DSCN0001

All the tubes are functional. I haven't been able to find a 4-400A(cheap enough) to complete to family.

[Edit: Size]

Proud Mary

Wed Feb 08 2012, 12:27AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Dave: a beautiful collection in lovely condition.

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