30-07-2020, 11:18 AM
It's not for substitution, Trevor. There are no shortage of cheap NOS ECH81 (The ECH83 is marketing ploy, same valve exactly), including Russian equivalents. I'd be mad to do that!
The only "AC" valve (which started as a battery radio valve) I'd replace with a Rod Pentode is the PX family triodes, they have direct filaments anyway and certainly 2 x 1p24b in parallel, with filaments in series / parallel and ballast resistors will replace the earlier ones.
It's purely for research as it's the most common mixer/oscillator in non-USA sets since it's introduction till the end.
Later I shall compare DC90, DF97, EC90, ECC85, EF80, ECF82 and Rod Pentodes, triodised, as self-oscillating mixers. Maybe PC88 or PC86 too as I think I have a NOS one.
The only "AC" valve (which started as a battery radio valve) I'd replace with a Rod Pentode is the PX family triodes, they have direct filaments anyway and certainly 2 x 1p24b in parallel, with filaments in series / parallel and ballast resistors will replace the earlier ones.
It's purely for research as it's the most common mixer/oscillator in non-USA sets since it's introduction till the end.
Later I shall compare DC90, DF97, EC90, ECC85, EF80, ECF82 and Rod Pentodes, triodised, as self-oscillating mixers. Maybe PC88 or PC86 too as I think I have a NOS one.
