Radio won't stop playing Christmas music

Interesting, that. I also had a Knight Kit FM receiver of that vintage. El Centro, California was a deep fringe area at that time and radio frequency interference from KGEI was a real nuisance. The detector used some crazy feedback circuit to make a narrow-band IF strip track the wide-band broadcast signal. (Oh, if I had known then what I know now.) I always figured the signal on the 25 meter was getting into the IF but maybe the tall antenna and feedline were resonating at 6 MHz.

Electrostatic loudspeaker perhaps? It's the wrong shape and size, but it might be possible with sufficiently thin gold leaf. The problem is that it would be really fragile, and not suitable for dragging across the desert.

The traditional inscription on the ark was translated to: "No User Serviceable Parts Inside".

Ever since touching the arc electrocuted and killed Uzzah, inumerable safety organizations have gone on a rampage producing draconian safety rules and regulations. Because of the obvious high voltage, the boom box ark was probably based on tubes, not semiconductors.