Toroidal transformers cause very little acoustic hum, unless the core
is not tightly wound or the copper wire windings are loose!
If you have to tighten the mounting bolt with a torque wrench
to get the transformer quiet, something is wrong!
Bert VE3NR
On 2020-10-19 19:59, Jim Spikes N4KH wrote:
Looking for details from anyone who resolved issues with excessive
transformer hum during transmit on a KPA-500.
I have a hum mitigation application note sent from Elecraft tech support.
But the procedure recommended is pretty involved - removing front/side
panels, un-plugging connections, removing the transformer, changing
positions of the rubber discs, and putting it back together. Possibly more
than once, depending on the results.
There is a risk of breaking something, and I'm not sure its going to solve
the problem if I'm successful. This is a new out of the box KPA500 kit.
If anybody has any lessons learned I would appreciate hearing them.
Jim, N4KH
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