Jim, I have put a bit of info up on your "radio's and audio thread" link hereCitroJim wrote: ↑28 Dec 2020, 08:59Neil, that's a magic bike
Not at all sure what a mercury vapour tubes in in the context of radio... The only mercury vapour tubes (valves) I know of are mercury vapour rectifiers but they were never used in small domestic radio, only in high power transmitters... Smaller ones, known as 'Tungar Rectifiers', were used in some battery chargers but I never knew of them being used in a small radio...
I must do some research Thanks for giving my brain something to do today!