[Elecraft] KPA 500 voltage drop on key down

[Matt Murphy]

I just set up my KPA 500 and the HV on standby is 72.5 volts.  On key down,
however, it drops to 48 volts and the lights in the shack noticeably
flicker a bit.

Would changing a the tap on the transformer potentially help things? Or is
the real issue the voltage drop between the pole and the wall socket?

Suggestions/ideas would be much appreciated, as well as tips for debugging
any issues with the household wiring.

Per the KPA 500 manual, the amp may fault if the voltage under load gets
below 60VDC, so running in it with reduced drive may be necessary. While
doing that wouldn't be the end of the world, I'd like to address the root
cause if possible.

73,
Matt NQ6N