[Elecraft] KPA500 Transformer

[Bert]

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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