The Ten-Tec RX-320D Receiver requires a very
low noise PC / Lap-Top and even more important
a PC /Lap-Top AC-to-DC Power Supply that is
really Noise Free.
http://swling.com/Radios.htm#RX-320D


Actually, you don't need that quiet of a laptop/p-supply. Just use the
serial to usb with ~30ft of USB cable length. Wrap 10-15 turns of the
cable through a ft240-43 toroid. Friend had to do this with a noisy dell
.... worked great. Keep the receiver 15-20ft from the laptop. He is now
running a new Acer and the problem is non-existent. I had no problem
with just a 6ft. USB cable and no choke on an HP. I was really
impressed. My $5000+ SDR transceiver beats it, but darn, at that price
it is a steal! I would place it into the HOT category of receivers ...

Regards,
JS