Re: When did Valve heaters change from 4v to 6.3v
Audio amplifiers using PX4 or PX25 valves would use 2-0-2 heater windings and they were still popular after the war.
You could build a PX4 Williamson amp with 340-0-340 and use the 12 volts to run the two B65 heaters in series.
Last edited by barrymagrec; 10th Feb 2018 at 6:37 pm.
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