You were spot on that it was not the PA. ?The power supply actually handles it all fine, what failed was not anything with the PA, as you surmised (well done), but the Droc buck converter I was using for almost a year to supply the QCX + with 12 volts from the 21 volt power supply to the PA. ? Has worked fine for a year but something in the buck converter failed. ?When you key the QCX + as soon as it pulls current from the buck converter, the converter voltage drops from 12 vdc to around 0.5 vdc….way too low for the QCX+ to operate. ? ? Thank you. ? ?All running fine now with PA off the power supply and QCX+ off a battery.

Will try to fix the buck converter…. will also build my own using Hans’ advise to use a 7812 regulator in TO-220 pkg with heat sink and a couple capacitors to provide 12 vdc at 1.5 amp (max).

Cheers

Eric?