[Elecraft] HELP! KPA-500 HV is 10 Volts

[Andy Durbin]

"When I powered-up the unit and tapped "HV" I get numbers between 9 and 11 
volts (expecting ~ 65 or 70 Volts)."

I'd suggest measuring the actual HV rail at the PA input spade terminal.  That will tell you if you have a real low voltage problem or a voltage sensing problem.  The interlock switch will need to be defeated which is not difficult but I leave that to your ingenuity.

If the voltage really is low then (switch off) disconnect the 60 V bus from the PA module (switch on) and measure again.  My HV supply is 80 V unloaded.

The interlock switch is there to stop you doing this so don't defeat it without considering the risks and taking appropriate precautions.  

73,
Andy, k3wyc