Winding a transformer

[j-po]

Here's a tricky question for you gearheads:
Can I wind on any secondary to an existing primary + iron or does the spec (inductance?) of the primary vary with what is on the secondary.
Would like to make a power trans out of an old solid state PT.

Your input is much appreciated.

[txbluesboy]

On a power transformer you can change the secondary to any voltage(s) you want without affecting the primary. Your wattage is limited to what it was before, of course, by the wire size and number of turns, and by the core dimensions. Just calculate the turns ratio and multiply by the new output voltage wanted. The wire size should change in reverse proportion to the change in turn count.

[Ears]

I imagine things change will change unexpectedly and non-linearly if you overwind to the extent where magnetic saturation of core occurs.

[txbluesboy]

If you leave the primary alone, the only way to saturate the iron would be to apply a higher voltage to the primary winding than what was on it originally. The secondary wont affect it. However as I said before you can't increase the rated wattage.

[j-po]

Thanks, that's what I wanted to hear. I think wattage will be sufficient, the iron is pretty big and it used to power a fair amount of watts out of some home hifi. All I want is 2x6V6 anyway.
I'll pot the trans with varnish. Possibly by brushing it on while winding.

A lot of trouble to save pretty much nothing. Homebrewing at its best, that is.