[tobych]

There's a little more detail about the Apollo situation on a post [1] by Neal Strickberger on Candlepower Forum:

"Chicken wire! Turns out this was added for the Apollo program, when they used the TVS-3s to light the pad. A 20kW short-arc fed with 400Hz 3phase fullwave rectified unfiltered power produces lots of RFI at 1200Hz harmonics, and when nice and focused with a reflector it was enough to shut down the capsule. So they made a Faraday cage."

[1] https://www.candlepowerforums.com/vb/showthread.php?348441-A...

[VLM]

Optical people are rolling their eyes at the size of reflector required for 1200 Hz.

BEST hope possible to make the story true would be clear glass semiconductors can detect incoming light so MAYBE germanium glass tube diodes hanging out in the air could get confused, although why a moon rocket would have bare unprotected glass semiconductors on the outside is a mystery.

[zbrozek]

_harmonics_ means more than just the first odd harmonic.

With 20 kilowatts flowing it's very believable that the comb reaches quite a ways up the spectrum. And the radiator doesn't have to be tremendously efficient or focused with that kind of input power to produce significant effects in unintentional receivers. Also remember that wiring harnesses in spacecraft are probably very long, so will be good receivers at many frequencies reaching quite low.