I once had a hum bar that I could not get rid of no matter how much I fiddled with the ground. Put new fittings on at the ground block, and away it went. I figure some previous tech must have cut off all the braid when prepping one of the connectors.
Another time had very, VERY faint hum bars, could barely see them except when very dark background. That one also stumped me for an hour or so. Finally noticed that the tap wasn't bonded, so twisted together 3 pieces of ground wire and used that to bond the tap in the ped, and presto! no more hum bar. Referred to maintenance to come out and put the heavy copper on it, which they wouldn't give me to go back out and do it myself. Year later I'm in that doghouse for a call at the neighbors, and my bond is still there. Knocked on the other sub's door to ask if hum bar ever cam back and he said No, it's been great, lol.
