[Elecraft] KPA500 Hum when off?

[Scott Manthe]

Jim,
My first KPA500 did that occasionally, so I don't  think it's an issue. 
I'd guess it has to do with line voltage variances.

73,
Scott, N9AA


On 6/11/13 10:51 AM, Jim Miller wrote:
> I leave my KPA500 back panel switch in the ON position most of the time and
> use the front panel switch to bring it to life.
>
> However in even when in the "Front panel off/Back panel on" state the
> KPA500 will occasionally hum for a few seconds.
>
> Is this normal? Any suggested causes to worry about?
>
> Thanks
>
> jim ab3cv
>