"Hal Rosser" wrote in message
...
--I expect the ballast is the critical component - some are magnetic, some
are electronic - its probably the culprit

Hello, Hal.

I suspected the electronic ballast in the "bad" light myself. They both use
electronic ballasts. Perhaps it's an unfiltered ballast in the "bad" light
or something like that. They both are supposedly made in the USofA so I
can't blame it on the Chinese tendency to eliminate unnecessary items like
filter capacitors to save 18 cents of the cost.

I hope you're wrong about the two lights switching places; somehow, I can't
imagine the "bad" light gradually becoming RFI-quiet over time... by what
mechanism could that happen?

I am judging the lights as they are... one is noisy, the other is quiet. It
is somewhat amazing that we are trying to make excuses for this situation
rather than accept that some lights are noisy and some are quiet! :^)