Hi Mike,
Tried DB-9 COM 1 of control RCC in place of using the USB and found no change. All Expert remote control functions work, except power on. I eliminated the amp as a problem buy unplugging the serial cable from Radio RCC and using a 9 Volt battery from pin 5- to pin 8+ and after a couple seconds the amp powers up. It seems that 9 volts is just enough and any less will not cause the expert amp to power up. What voltage should be seen on pin 8 of radio RCC to power up the expert? Is pin 8 to be 5 volts normally when radio link is established and then rise, to say, 12 VDC to cause startup of amp? I guess I can try COM2 using the same cables to see if the amp will power?
73,
James HK3AVR / K3AVR