It's not so far out of a suggestion. One of my Zenith console
radios has some remote control solenoid mounted inside a metal
box that's lined with rubber.

The sand is a pretty good thermal conductor (compared to air),
better than epoxy. In fact they fill the cheaper type of epoxy
potting material with coarse quartzite or powdered limestone
to improve its the thermal conductivity. It's the air trapped
between the grains of sand that provide some thermal insulation.
Mixing sand with epoxy or oil fills the interstaces which would
otherwise be filled with air.

Some one mentioned coating the laminations with nail polish as you
stack them up to glue them together. Either that or little varnish
would most likely have prevented any buzzing laminations.

Not taking the laminations off is a good suggestion too if it's
possible. For instance microwave oven transformers just chisel
off the secondary and wind a new one. Though for smaller
transformers that often isn't possible.




Stray Dog wrote in
.org:


This might be a little "far-out" but, besides just buying more epoxy
and just doing it right, maybe you could find a can or metal box, put
the transformer into the box, and fill the box up with enough sand
that you have 1-2 inches all around the transformer, and that might
muffle the buzz. You'll need to worry about heat dissipation through
that sand which will act like an insulator, but if you are on the air
only a couple of hours per day, it should not get dangerously hot
(however, many of the old hermetically sealed transformers were
burried in a waxy-tar that was quite hard at room temperature).

Your other option is to figure out some clamping arrangement so that
the laminations are held close and tight.

Re-winding transformers is fun, but next time you want some off-beat
voltage, maybe scrounge up higher voltages (eg. car battery chargers)
and use either a variac or power resistor (with sufficient heat
dissipation) to bring the voltage down to where you want it and save
yourself the headaches and earaches. Or, don't take the laminations
apart but feed the wire (stranded) through the holes that are left.

Or, other kludge-cheapskate approaches.

Good luck.