> Marconi DEV triode (1924). designed for low capacitance to improve high-frequency performance in short-wave radio applications
< Ediswan AR (1922), Cossor P2 (1922). Cosmos SP18 (1925). The Cossor device used an
unusual 'hat' construction to avoid infringing patents which specified tubular electrodes.
This construction can also be seen in the Cossor 610FP, right. Cossor
> GEC DET18 and Eimac 35T, very similar construction despite being made on opposite sides of the Atlantic. I've found no reference to either of these in any of my books.
This info from Manuel Carbonell : 35T: Equivalent to 3-50A4.. High mu triode,
oscilator, class-B modulator or low frequency amplifier, class-C buffer, doubler or
> Tetrode with side terminal, Philco 43 Pentode (1931)
< Two valves with angled electrode assemblies, left one unmarked, right STC 'Micromesh' R3 indirectly heated full-wave rectifier (1932).
> VT121 triode, possibly designed for telecom repeater applications, as
it's marked 'GPO' (general post office)
> Ediswan ESW20
I currently have 3 valves like the first
two of these on ebay