I've discovered the source of the RFI that I thought initially was an
internal R-5000 problem. It turned out to be my home computer network
LinkSys BEFSR41 router is causing the RFI with my shortwave radios on at
least one or more frequencies. The first frequency that I observed was
11955 kHz. The router and my computer, printer, scanner, and cable modem
are in the same room with the shortwave receiver. The distance between the
router and receiver is approximately ten feet across the room. I've
isolated the RFI source to the router by leaving a battery-powered receiver
on tuned to 11955 kHz and powering up and down individually the computer,
printer, scanner, cable modem, and router. Thank you all for your
suggestions.