[Elecraft] KPA 500 Hum

[Tom]

Just received a KPA 500 and KAT 500 yesterday.  Using them with my Icom
7300.  I know the manual says to expect some hum from the KPA 500 but I
believe mine is more than a hum.  When I send CW I don't need to monitor
the radio side tone.  I just have to listen to the amp. :-)  Anyone else
experience this?

My HV voltage is 75 at idle.  I am using 120V power.  When I key down it
drops to around 58.  Manual says 60+ is best.  Don't know if this has
anything to do with the hum?

I have not contacted Elecraft yet.  I wanted to hear what folks say first.

73,
Tom
KQ5S