I got the following from rec.audio.tubes:
"Such transformer primaries have very large and NON LINEAR impedances
when tested with low and medium frequencies. Non linear in the sense
that the impedance is a function of the actual level of the test signal
used."
He also said that since I found both to draw the same current from the
mains when run with no load, that would indicate there's no problem at
the low frequencies. Perhaps I'm lucky and there is really nothing
wrong. As for the buzzing, there's less of it when I connect the other
primary taps, and I can live with the somewhat lower output voltage.
Tom W8JI wrote:
> 1.) There should not be a conductive path between laminations.
There isn't. I put the core together with nail polish (I don't have
shellac or transformer epoxy), and that's a good insulator. The bolts
use insulating spacers, and pulling them out didn't do anything anyway.
> from side to side. I've seen people actually drill into laminations to
> mount components!
Ever seen microwave oven transformers? They usually have welds across
the core...
> 2.) Run the transformers full voltage ( be SURE they are in a grounded
> enclosure when powered up) with no load.
I had tested them at full voltage, and both draw the same current from
mains. But why should I have them in a grounded enclosure, do you mean
for safety?
I guess I'll try running them overnight on a fused circuit and see what
happens.
> A single shorted turn will behave much like you descibe, and evetually
> make the transformer fail.
The problem I'm having with the shorted turn theory is that this should
reduce output voltage, but I get normal voltages on all secondaries.
Unless, of course, it's the electrostatic shield. Maybe I should stick
a thermocouple in the foil see if it gets unusually warm.
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|