[Elecraft] Nasty spurs on RX with new KPA500

[Andy Durbin]

Nothing heard or seen on 10 m with my kit built KPA500.

I'd suggest disconnecting the RX from the KPA500 and connecting it directly to the antenna.   Does the problem go away?
If not, connect the RX directly to the dummy load.  Does the problem go away?
If not,  disconnect everything else from the KPA500 except the power cord.  Does the problem go away?
If not, connect the KPA500 to an outlet on a different circuit.  Does the problem go away?

Hopefully, one of these steps will give some information on the source of the problem.

73,
Andy, k3wyc