I have seen portable radios that would automatically switch to
'headphone-antenna-mode' when I plugged headphones in. This was
usually only on FM, but I'm guessing that is what's happening here.
Somehow it's switching the whip antenna off when headphones are
plugged in, so that you could use the radio in a coat-pocket, etc and
still get some FM reception. Obviously it shouldn't do it for SW, but
it could be a design oversight?


--
Neil Goldstein
http://www.neilgoldstein.com