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Old 18th Jan 2020, 1:01 pm   #10
David Simpson
Nonode
 
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,838
Default Re: DE5 valves plus others, of any interest?

Hello Duncan, please put my name in the hat. Its no secret that I've a keen interest in DEV valves(See Marconi DEV Type Valves - 24th Sept 2017, & "Testing DEV Valves on AVO MK3" - 30th Oct 2017).
These valves started to appear just after the 1stWW & were in use well into the 1920's. B4 Base, 2V filament, anything from 60 to 130V HT usually, low Ia, some only worked at very low -ve Vg, and Gm in the region of 0.4 to 1.5mA/V was common.
Working & in good condition, they can be worth a few quid, I have to be quite honest. Although heating up well enough with 2V Vf, they often(due to their age) exhibit low or negligible Ia, hence are only good for display purposes(often in valuable old Marconi sets with exposed valves).
However,again being quite honest, the "Cruciform" (cross-shaped with big brass side connections) Bright Emitter & Dull Emitter valves are worth "Rocking Horse Manure" prices if(& its a big if) they still work OK. (I've built a B4 adaptor rig).
These valves, being nigh-on 100 years old, can be very easily phooked. Best bet would be to ask an experienced valve testing Forum member nearby, who has tested them(preferably on an AVO VCM) in the past, to see what state they are in.
Like your friend thinks, I wouldn't give them away unless the recipients agree to the caveat - Not To Be Flogged on Ebay ! Otherwise, take them along to the next nearest BVWS Swapmeet & ask Mike Barker to auction them & the funds going to the R & TV Museum.

Regards, David
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