On Oct 25, 12:25 pm, raypsi wrote:
Hey all:

I tore down a transformer I got from ebay it was a Zenith TV power
transformer from days gone by. Re wound it with 17AWG wire on the
secondary and primary. It powers up my 4-1000A filament nicely with
7.25VAC from 120VAC mains. I used a penta-filar winding on the
secondary. Shimmed the bobbin in the core window with some 1/8 thick
virgin teflon. Epoxied the windings to the bobbin. This was a 240VA
transformer and now is a 83watt buzzer / 157watt filament transformer.

So what is the cheapest I can gits away with sealing these laminations
from buzzing, I used up all my epoxy sealing the windings.

73

n8zu

I finally got around to clamping the transformer down with grade 8,
1/4inch bolts and nuts That didn't help, luckily I found my 3 hour
epoxy, ran the transformer for 3 hours straight to heat it up, took
the bolts out and with a putty knife slapped on some microwave heated
epoxy on the lams. That took the buzz down to below the level of the
fan noise. In dead silence you can still hear it. Nowhere can you feel
the buzz.

73

n8zu