WTF?

After a highly productive hour on 15m this afternoon, I turned to some SSB 'CQ'ing on 14MHz.

Hmm!  Something odd.  When I transmitted, I could hear some splatter, a bit like adjacent channel QRM coming through the FT-450's internal speaker!

What on earth was this?  When I pressed transmit and didn't speak, the power output meter on the rig was going up and down, as though I was saying something, with the strange 'QRM' coming out the speaker again.

Arrgghh!!!

After a moment of wondering what was happening, I pulled out and replaced the microphone connector (I have a cheap, but very good Behringer studio mic on a boom, with a handheld PTT switch).  The same problem.  I then pulled out the jack plug that connects the microphone to the input/PTT socket.

That was it!  Seemed like the connection in that jack plug had gone a little dirty or lightly corroded, or just a weak physical connection somewhere.

Quite a few audio checks later, the problem had vanished - hopefully, for good!