Metropoulos Forum

Anyone know how the "sag" or power drop is measured on a power transformer?

D. Friedman says the sag at the power supply secondary winding is a sag in the current, so you'd have to find a way to measure that. Same issue as measuring mA of current when biasing tubes. Possibly you could measure the voltage & then use ohm's Law to compute the current by plugging in the resistance load value & the voltage value, then doing the math?

Maybe the good old-fashioned osciliscope/dummy load/frequency generator setup would help or be neccesary? Dave?

measure plate voltage at idle and at full distortion. should drop around 90v

So I guess its not so much what the PT does by itself , but more of what the rest of the amp is doing to cause it to.

its about how the PT interacts with the rest yes