In article . net,
says...
You might consider getting a portable "reel" antenna.
23 ft, plugs into the radio or attaches to the whip.
A clip at the far end can be used to attach it to a window
frame, etc.
Sangean ANT-60

I bought one of those to go with my DX-398, mostly just to avoid having
to figure out how the external antenna connection was supposed to be
wired. Unless you have a funky antenna connector on the radio, I'd say
just get a small spool of wire and attach it to the whip antenna. Most
people probably have something laying around the house that would work
fine. The fancy, wind-up spool thing really isn't worth the money.

$12.95 plus shipping at
http://www.universal-radio.com/catalog/sw_ant/3184.html
(possibly slow to ship, people have different experiences buying from
Universal. I've had good service from them)

That's where I got my ANT-60. They shipped almost immediately, and that
was during the Christmas season.

-- Jay