[brian-armstrong]

It's easy to think this is something dramatic and mysterious, but it's much more likely that it's actually quite mundane.

Building a dead man's switch that operates over shortwave is a pretty iffy proposition. People might jam you just for fun. You could experience prolonged channel degradation. Also, your transmitter could just plain break. If it were that kind of device, operating continuously since the 1980s, I'd be surprised if it hadn't triggered accidentally already.

[S_A_P]

Oh I totally agree- I was more just saying that is what I picture in my mind when I read about these "mysterious" transmissions. Seem like a subplot to a movie.