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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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23rd Feb 2019, 1:33 pm | #1 |
Hexode
Join Date: Feb 2008
Location: Wrexham, North Wales, UK.
Posts: 466
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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. |
23rd Feb 2019, 1:42 pm | #2 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Mystery Valve
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23rd Feb 2019, 2:02 pm | #3 |
Hexode
Join Date: Feb 2008
Location: Wrexham, North Wales, UK.
Posts: 466
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Re: Mystery Valve
Gotcha!
Many thanks G |
23rd Feb 2019, 3:48 pm | #4 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,857
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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 |
23rd Feb 2019, 5:53 pm | #5 |
Hexode
Join Date: Jun 2009
Location: Cheshire, UK.
Posts: 363
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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 |
24th Feb 2019, 3:44 pm | #6 |
Retired Dormant Member
Join Date: Feb 2019
Location: East Midlands, UK.
Posts: 36
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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). |