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What are the most interesting vacuum tubes in your collection?

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radhoo

Sat Aug 06 2011, 09:35AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

5980 BS-2 a GM detector tube for Gamma radiation:

I have two pieces, so I can trade one for a different tube.

radhoo

Sat Aug 06 2011, 09:38AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

6390, a Klystron reflex tube, yet another candidate for my UHF experimental setup.

It features some interesting characteristics:
Output frequency: 6700 MHz -> 11050 MHz
Output power: 60 mW max.

radhoo

Sat Aug 06 2011, 09:42AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

PEK-110, mercury vapour arc lamp, a lab precision UV light source,

It works at 18V, 5.5Amps, and it requires a short HV pulse (aprox 1500V DC) to ionize the gas and start the low voltage discharge.

Proud Mary

Sat Aug 06 2011, 10:38AM

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

radhoo wrote ...

5980 BS-2 a GM detector tube for Gamma radiation:

I have two pieces, so I can trade one for a different tube.

Recommended anode resistor: 1MÎ©
Maximum starting voltage: 640V
Recommended operating voltage: 700V
Operating voltage range: 660 - 800V
Maximum plateau slope: 20%/100V
Minimum dead time: 45 Î¼s
Gamma sensitivity Co60 (cps/mr/hr): 3.5
Tube capacitance: 3pF
Weight: 10 g
Maximum background shielded inside 50mm Pb + 3mm Al: 10 cpm

radhoo

Sat Aug 06 2011, 11:23AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

A ballast tube, K80-B, from 1935:

Thanks for those details, Stella!

radhoo

Sat Aug 06 2011, 11:27AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

A neon filled tube, Philips 4378. Breakpoint between 80 and 120V .

radhoo

Sat Aug 06 2011, 11:35AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

Here is a cold cathode triode, JAN-CW-313CD painted in black to reduce ambient light photoelectric effects,

This tube originally contained a small quantity of Kr-85, a beta emitter. The half life for this isotope is of aprox. 10years. The tube doesn't present detectable radiation emissions, not a big surprise since it is from 1950 and the Kr-85 inside is long gone.

Designed for 200V, 25mA.

This last pic shows the tube being lit by the strong RF field of my GI30 VTTC.

radhoo

Sat Aug 06 2011, 11:39AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 700

GI-30, a Russian double tetrode:

And a VTTC tesla coil that uses this tube:

Schematics also available here:

Proud Mary

Sat Aug 06 2011, 06:51PM

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

radhoo wrote ...

Here is a cold cathode triode, JAN-CW-313CD painted in black to reduce ambient light photoelectric effects,

This tube originally contained a small quantity of Kr-85, a beta emitter. The half life for this isotope is of aprox. 10years. The tube doesn't present detectable radiation emissions, not a big surprise since it is from 1950 and the Kr-85 inside is long gone.

A trace of the 85Kr must remain, but with an average Î² energy of just 251 keV for the main (99.57%) disintegration mode, almost nothing will escape the glass envelope - which is why this isotope was selected in the first place. A Î² scintillator of suitable energy response and PHA could still detect the residue if the glass was removed.

85Kr is perhaps one of the most searched after isotopes in the world - searched after because tiny trace levels of 85Kr in air or water may point to undeclared or clandestine Pu production nearby.

Proud Mary

Sun Aug 07 2011, 02:41PM

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

RCA 955 "Acorn" UHF Triode

'DETECTOR, AMPLIFIER, OSCILLATOR'

"Especially for wavelengths between 0.5 meters and 5 meters"

955 was one of the first valves to be designed specifically for UHF applications in 1934. The revolutionary 'acorn' design allows the shortest possible paths to cathode, grid, and anode. Careful construction will allow oscillation up to about 1000 MHz. They are great fun for a one valve VHF/UHF super-regenerative receiver, as well as for many more serious uses.

It is possible to solder directly to the pin-outs - on a cut-out in a PCB, for example - but there is always a risk of cracking the glass seals. I was lucky to find a stash of these purpose built ceramic 'acorn' valve mountings in nasty used condition, but most of them have come out very nicely after a good wash and brush up in the kitchen sink.

Full 955 data sheet with nifty application circuits is here:

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