Remember, cap. I/P filters are voltage rich and current poor, while choke I/P filters are current rich and voltage poor.
Because of the I2R heating associated with filter charging pulses, the full RMS current rating of a rectifier winding is not available as B+, when cap. I/P filtration is employed. A conservative rule of thumb that's particularly important when SS diodes and large 1st capacitances are selected is that 50% of the AC RMS current will be available as B+. Regardless of whether tubes or SS are being "fed", overheating the power transformer must be avoided.
Because of the I2R heating associated with filter charging pulses, the full RMS current rating of a rectifier winding is not available as B+, when cap. I/P filtration is employed. A conservative rule of thumb that's particularly important when SS diodes and large 1st capacitances are selected is that 50% of the AC RMS current will be available as B+. Regardless of whether tubes or SS are being "fed", overheating the power transformer must be avoided.
1. calculate filament power required, make a tally of all your tubes, with filament volts vs. filament current, tabulate them to get the total required..
2, calculate the plate power anticipated, if class A that is simple, if class AB there is a standby plate power and full power plate power...so in this case i use the full power plate power needed...
3. add the two together and you have the dc power asked for from the psu..
4. know your psu configuration, if tubed then filament power needed to be added, for plate power about 10 watts is a good figure...
5. once you get them all figured out, then you should have the dc power required,
6. if the total power is reckoned with, i introduce a factor of 0.6 to get the primary volt amperes....
this is how i design for my power traffos, and always, i tend to build bigger than what was originally required.....
YMMV.....
Keith Fenner's "better to be looking at it than looking for it" applies in this hobby, along with the machine shop. A cool running, unstressed, power trafo will not fail.
Heat is THE mortal enemy of all things electronic.
