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What are the most interesting vacuum tubes in your collection?

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radhoo

Tue Sept 11 2012, 11:44AM

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

That is a valuable piece of information, thank you, Stella.
My Sinometer VC2000 unfortunately stops at 2.4GHz, making my work in this area a bit more difficult. Perhaps I will get back to some of my other tubes, that can work at a smaller frequency, such as some of the Klystron tubes that are still waiting for some of my time.

Here are some of my hottest tubes:

Of course, being hot refers to the radiation emitted as most of these are radionuclide enhanced ionization tubes.
I've recorded a few videos showing the dose, I just need to put them together and will be posting them here.
From right to the left:

1. JAN4C35A, this is a Hydrogen Thyratron for radar modulation applications. 8KV peak, 100mA average, 90A peak anode current. The top seal uses Uranium Glass, making it radioactive. 0.90uSv/h right near the uranium glass.

2. JAN8370, another Hydrogen Thyratron, dating back to 1924. Again the top glass is Uranium glass. 0.80uSv/h

3. 313CD, Cold cathode neon triode, from 1952. 200V, 25mA. Kr-85 activator . No longer radioactive, at least not detectable outside the tube. Probably due to krypton's short life.

4. JAN346B, Cold cathode neon triode relay from 1924. 225V, 30mA; Average life 10Hours. One of the hottest tubes, thanks to the Radium Bromide (RaBr ) it contains. Datasheet here:

2.40uSv/h

5. 1B26, TR Switch tube, the smaller variant of the 1B24. K-band 23.6 to 24.6GHz, integral cavity, tunable TR switch.
This tube was developed by Westinghouse under the guide of C. W. Zabel of the MIT Radiation Lab.
Details on TR Switches here:

. Contains RaBr. 3.0uSv/h

6. Eii-43-100 Spark gap radioactive tube, Cs137, still very active 3.5uSv/h

7. 11TN40 , not showing any detectable outside emissions. I am looking for some info on this tube, if anyone has anything..

8. TG-77 Signalite Spark gap radioactive tube, Cs137, 1.7uSv/h

9. MA340F TR Switch, it was probably using Cobalt 60, so not radioactive anymore.

10. 1B22. Argon-Hydrogen filled spark gap, for use as radar modulator. Corona trigger electrode inside the cathode, to start the firing. Aluminum cathode, nickel or iron anode. By design the tube must be operated with the cathode opening downward; the aluminum eroded by sparks is mostly transferred to anode, leaving approximately constant the electrode spacing through the useful life.
2.7KV per gap firing voltage, 75A peak, 75mA average, 1100pps max.
Introduced by WE during WWII. Registered in 1948, when already discontinued. Third issue of datasheet dated 1943.
Some sources indicate it contained up to 3uCi of Ra226, probably as RaBr.

Proud Mary

Tue Sept 11 2012, 06:46PM

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

I've got two 4C35A thyratrons, but I never knew about the U glass in the top seal! I shall have to take a measurement of it when I have finished painting my house.

radhoo

Tue Sept 11 2012, 09:00PM

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

Proud Mary wrote ...

I've got two 4C35A thyratrons, but I never knew about the U glass in the top seal! I shall have to take a measurement of it when I have finished painting my house.

Yes and it's quite active, at least when compared to other uranium glass samples I tested. I didn't have the time to finish the video featuring these tubes, but regarding the two thyratrons, here is how they look under UV:

Left picture: 4C35A Right:JAN8370

The uranium glass green fluorescence under UV, is clearly visible.

radhoo

Wed Sept 12 2012, 07:37AM

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

I found a fragment of 11TN40 's datasheet. But I still don't know what radionuclide was used in this tube.

Long time ago, I got in contact with several similar tubes. Russian or Czech, I don't know. I remember they were same format and size, except the little protuberance at one end, they looked like fuses, and were painted red or green, having the trefoil on the side. Despite the tick case, I managed to open a few. Now I'm trying to find out what was inside.

radhoo

Wed Sept 12 2012, 08:23AM

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

I found the device in which the 11TN40 was used. Named BS2, of Czech origin. But I still don't know what's inside that tube.

VEDENI means "LED"
PRISTOJ means "Standing Position"

Proud Mary

Wed Sept 12 2012, 09:19AM

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

I'd say that 11TN40 was a mains supply anti-surge/spike suppressors with the radionuclide added to create pre-ionisation conditions to speed up the switching action.

Working voltage 250V
Ignition (clamping) voltage 400V
Drop out voltage 200V
Peak surge voltage maximum 1000V for 50Î¼s
Maximum conduction current 40A for 0.25 seconds.

So it will ignite (zÃ¡pal) at 400V and conduct until the voltage falls to 200V.

I'd guess that the radionuclide would be an alpha or beta emitter, as these can cause strong local ionization in the gap without being able to escape from the envelope in much quantity, if at all. Any gamma emission will be an unwanted by-product.

(I use a small piece of pitchblende - uraninite - as my test source, as this is not controlled by the UK Government due to the Geological Specimens Exemption Order 1962 and so does not have to be registered under the Radioactive Substances Act 1993.)

Proud Mary

Wed Sept 12 2012, 09:21AM

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

radhoo wrote ...

Proud Mary wrote ...

I've got two 4C35A thyratrons, but I never knew about the U glass in the top seal! I shall have to take a measurement of it when I have finished painting my house.

Left picture: 4C35A Right:JAN8370

The uranium glass green fluorescence under UV, is clearly visible.

I never stopped to think why the top of the envelope was a strange colour! I will put up a photo and measure the activity of mine when I have got through with the house decorating.

Steve Conner

Wed Sept 12 2012, 10:05AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

The "BS2" device looks like a surge suppressor for a phone line. "Vedeni" probably means "line" and "Pristroj" "apparatus".

Maybe it was a Cold War-era gadget to protect military field telephones from EMP. Using radioactive things to protect against other radioactive things, FTW.

radhoo

Wed Sept 19 2012, 08:43AM

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

A 3.5KW Monster, the GU-5B triode.
This nice tube was kindly donated to me by Vasil, together with 3 tesla coil full assemblies (transformers, high voltage caps, and everything else). When one gives out of his most precious belongings, is probably the best case of magnanimity. Thanks Vasil.
The GU-5B was used in his GU5Bzilla, that I will reassemble soon:

Datasheet:

radhoo

Sun Dec 30 2012, 08:21PM

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

There are some electronic tubes that contain small quantities of radioactive materials to enhance the internal ionization processes. Such tubes have been used in the 20th century mostly in radar technology. Using a Geiger dosimeter, I have created a top of the tubes in my collection, based on their measured activity:

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