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Old 23rd Feb 2019, 1:33 pm   #1
kestrelmusic
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Default Mystery Valve

I have a mystery valve which popped up in a job lot. It looks like a directly heated triode with a single filament stretched between the end contacts, a spiral grid and what looks like a nickel anode.

A couple of not-very-good pics attached. Can any learned person identify it for me?

Thank you.
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Old 23rd Feb 2019, 1:42 pm   #2
ms660
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Default Re: Mystery Valve

http://www.r-type.org/exhib/aae0007.htm

?

Lawrence.
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Old 23rd Feb 2019, 2:02 pm   #3
kestrelmusic
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Default Re: Mystery Valve

Gotcha!

Many thanks
G
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Old 23rd Feb 2019, 3:48 pm   #4
David Simpson
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Default Re: Mystery Valve

Hello Kestrelmusic,
If you look back through "SEARCH", you'll see that I had a couple of threads about this type of valve :-

Components & Circuits, 24th Sept 2017, "Marconi DEV Type Valves"

Test Equipment, 30th Oct 2017, "Testing Marconi DEV Valves on AVO Mk3"

I hope they might be of some help. For a nigh-on hundred year old valve, these valves are surprisingly robust, and can still work OK. Not much Gm, though.

Regards, David
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Old 23rd Feb 2019, 5:53 pm   #5
Wellington
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Thumbs up Re: Mystery Valve

1919 — wow!

Just for convenience, here are the links to David's references:

Marconi DEV Type Valves

Testing Marconi DEV Valves on AVO Mk3
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Old 24th Feb 2019, 3:44 pm   #6
Dave1000
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Default Re: Mystery Valve

Very interesting. The jacket details are not at all like "modern" valves - the leg that has been tipped (the dead-end bit of glass, right and below in the second pic'), would near certainly have been used to evacuate the valve.

The last time that I saw this type of design was in a 1950's paper which investigated emitter chemistry for discharge lamps (by Cayless??). The evacuation port/connection/leg was frozen in that example, to freeze-out carbon dioxide - an extremely simple method achieved from beautifully simple design, derived from admirable lateral thinking, to study decidedly complicated chemistry. Today, it would not take 1% the ingenuity required back then...……….. technology does make us so increasingly idle in mind and body (perhaps).
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