determining PT plate currents for used TF's

[imaradiostar]

I've spent the last few nights in front of the sofa with my wife measuring the DCR, voltages, weight and dimensions of every random power transformer I've collected over the last 12 or so years. I've spent some time with Duncan's PS simulator and I'm ready to start plugging these things into a prototype chassis to determine the best use for each of them. I'm concerned for how much each PT should be loaded and what should be an acceptable voltage drop during use.

Is there a standard percentage voltage drop that's considered acceptable for a transformer? None of these PT's will end up in amps with huge numbers of tubes so I'm not that worried about filament supplies but I want to make sure I'm not overloading the plate windings. I want to have an idea of what to look for so that I can make a judgment call when I've got a prototype amp plugged into the load box and the signal generator running.

How does amp use figure into it? I assume that a class AB amp intended for power amp distortion is going to need more reserve current than a cleanish Fendery amp with large filter caps that I don't intend to push very hard. Is this so or am I confused?

jamie

[imaradiostar]

I spent HOURS last night crunching numbers and working with Duncan's power supply sim. I had transformers spread all over the kitchen table!!

I'll probably post some numbers here eventually...

jamie

[gwbdopesmoker]

umm

I don't know how accurate reverse engineering a pt
would be using raw DVM type measurements. For instance,
you certainly couldn't judge the amperage of the windings
for the heaters or even the secondary.

[Enzo]

You could make a variable load and watch voltages and see how much load it takes to bring them down some arbitrary percentage.

[imaradiostar]

sounds like a good tip- I guess what I'm looking for is that arbitrary percentage!

jamie