K3HVG wrote:
I've been going through some transformers to see what to keep and what
to lighten the load, so to speak. I found one that I can't quite figure
out. The thing is about the size we'd see on a 60's TV set. Nice piece
of iron and useful. The issue is this: There are four sets of windings.
The B+ set is easy, color and resistance are consistent with the
winding. There are 3 other windings. One is identifiable as the 5v
filament winding, another as the 6.3v winding, leaving what I believe is
the primary (blinding glimpse of the obvious?). There are 3 wires left
over for (what I believe is the primary. One black lead that pairs with
another dark color wire. They ohm out as would a primary winding; that
is, low resistance but an obvious inductive reactance. The bug is that
there's yet a third wire associated with this pair and the resistance is
several hundreds of ohms in relation to the other two. Any ideas? It
can't be a CT, of course, and its way too high resistance to be a 220v
tap. Also, the wire size of the "primary" is #16 and this outrider is
maybe #18 or #20. I didn't just fall off the turnip wagon but this is a
poser?

Apply 6.3VAC to the 6.3V winding, from a filament transformer. Now
measure the voltages on the other leads and see what they are.

Yes, the unloaded voltage will be higher than the loaded voltage. Yes,
if you energize the secondary, the measured primary voltage will be
lower than normal since the transformer ratio is set up to account for
resistive losses and you now have the resistive losses PLUS the reverse
of that step-up. The two errors more or less cancel one another out,
and you wind up pretty close to the right value.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."