I never tried a ball. But I know on 160m mobile, corona is
very common if you run the juice. The ones I talked to used
metal balls for that...I didn't know a non conductive ball would
work...Maybe it will, but I never tried it...I used to talk to a guy
across town that worked 160m mobile every morning. He ran a
KW, and he used to say his antenna glowed a kind of blue color
most of the time around the top. MK