Hi Larry,

If you really had a shorted turn in your filament winding, the
transformer would be getting very hot, and growling at you.

If it is not getting getting really hot, and growling,
I would expect that low filament voltage is more likely
he result one of the following:

0) normal
1) primary voltage that is down around 100V, or 120V connected to
a 135V tap on primary
2) excessive filament loading
3) mistaken use of 5V filament winding for 6V filaments.
4) a bad voltmeter
and lastly,
5) an improperly wound transformer.

One thing to note, though, 5.6 V is not even 10% low in voltage. The
tube manufacturers allow that much margin.

-Chuck


Can one tell if a pwr xfmr is good or not by measuring the (unloaded)
primary current? I have a large surplus unit that I want to use for a
project. It's rated for lots of current and weighs over 11 pounds.
When I measured the pri. current, it was 0.31A at 120VAC with no load on
the transformer.

If this is not a definitive test, is there a relatively simple test that
I could do short of fully loading the secondaries and watching for
excessive temp rise?

My SET amp seems to have a shorted turn in the 6.3v winding, shows 5.6v
unloaded. It would be nice to use the "new" xfmr to rebuild this amp and
make some improvements.

Thanks for any info.

-Larry