On Mon, 26 Aug 2019 19:22:35 -0700 (PDT), wrote:

A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

One triode from that era is the A415. The datasheet lists Va between 20 and
150V, saturation current of 30 mA and default anode current of 3 mA.