[Elecraft] KPA500...standby vs. operate

[Andy Durbin]

"It all depends on where it is measured. It is switched after the measure point, so you will see a proper reading in both STBY and OPER.
It is not applied to the PA in STBY, though."

Yes indeed.  In the PA module PA voltage and current are measured before K4 which is controlled by "60V ENABLE".  60 V to the PA module is controlled in the power supply by K1 which is labeled "60 volt enable" and driven by "60V ENBL" from the interlock switch.  At a casual glance one might think "60V ENABLE" and 60V ENBL"  were the same signal but it seems they are not.  "60V ENABLE" seems to trace to "EN60V", then "EN60VA", and then "EN60A" from the MCU.  

The connector numbering and signal names used in the KPA500 always make signal tracing an "interesting" challenge.  I had to look because I often leave my KPA500 in OPER for hours when I'm not using it.  Still can't see why that would a problem though. 

73,
Andy, k3wyc