I may have missed this in other replies, but one of the fixes for this issue with the RCI DX (SMT) radios was to remove the SSB IF filter and cut the traces under it that went to the lands for the bypass cap completely off the board, then re-install that filter and re-tune the receiver. I've done that in many of those SMT RCI's and its always helped with the white noise issue. Seems like those traces allow the receiver to pick up stray chassis garbage even if they're not in use.
