UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Output transformer

kalee20 · 24th Aug 2019, 10:49 am

What is the output valve, triode or beam tetrode/pentode?

For beam tetrodes or pentodes, the optimum load is approx. 0.9 x Va / Ia where Va is the steady-state anode - cathode voltage (don't forget to allow for cathode bias resistor drop) and Ia is steady state anode current. Triodes are a bit more complex because generally the input signal has to be larger and you are constrained by not taking the grid positive.

For a mains output pentode, yes I agree 17k does sound high.

24th Aug 2019, 10:49 am	#5
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,081	Re: Output transformer - when needs must What is the output valve, triode or beam tetrode/pentode? For beam tetrodes or pentodes, the optimum load is approx. 0.9 x Va / Ia where Va is the steady-state anode - cathode voltage (don't forget to allow for cathode bias resistor drop) and Ia is steady state anode current. Triodes are a bit more complex because generally the input signal has to be larger and you are constrained by not taking the grid positive. For a mains output pentode, yes I agree 17k does sound high.