After making some changes in the station, and setting up the 480 with 
the solid state amp, I found a serious RFI problem on 15 meters. 
Anything more than 60 watts of computer generated cw caused things  to 
go crazy. The rig would lock in transmit and keep repeating stuff.  30 
watts RTTY caused the same problem.   If I tried the amp, the pc would 
either lock up, or sometimes reboot.

At first I thought it was the 4 port USB to serial adapter.  It does rig 
control for 2 radios, also cw keying, and FSK keying.  After some head 
scratching and some trial and error, i  figured out it was the pc 
keyboard.  Put a split ferrite at the keyboard end of the cable and it 
resolved 80% of the problem.  Put 2 toroid doughnuts at the pc end of 
the cable, and all is well.

73, Steve KW3A