[genewitch]

Even very expensive linear supplies will have Vpp of a few millivolts or microvolts "ripple". Vpp is voltage peak to peak, which you wouldn't expect on a DC device, but there you go.

i didn't read the article and i don't know the expertise of the author, but depending on the type of antenna you use, you may have to choke literally every wire in the "shack", KB/mouse, power, speakers, ethernet, etc. Although, funny enough, this is for the inverse case - the radio messing with the computer!

I wonder if an RF choke (AKA a 1:1 Current Balun) directly attached to the UHF port on the back of the radio would help in this circumstance - the feedline is probably coupling with the USB cable!