Based on my experience last night, using a cassette recorder seems to be my
only workable approach.

At my previous location, the electrical noise was so bad that when I used my
laptop near the radio I didn't notice any change in the noise level. In this
quieter location, it's a totally different story.

I set things up last night. I used a patch cable with a ferrite core, as you
suggested, to connect the radio to the laptop. The arrangement worked fine
when I began my tests, using a good strong 19-meter station (probably VOA).
Things were different, though, when I tried to tune in weaker stations. I
encountered serious electrical noise.

And the noise was coming from the laptop's AC power adaptor, not from the
laptop. I powered down and disconnected the laptop, leaving the AC adaptor
plugged into the wall. The noise was just as strong as before. As soon as I
unplugged the AC adaptor from the wall, the QRM vanished. I tried using
ferrite cores at various locations on the AC adaptor cords, but none of them
made any difference at all.

I can actually use the radio-to-laptop setup if I run the laptop on its
internal batteries, but that would give me less than 90 minutes of useful
time (at least that's what my laptop's manual gives for the average time
between charges). That's not acceptable, since I'll want to spend more time
than that at the radio when reception is right.

I guess I'm back to using an old-fashioned cassette recorder for now.

--Larry