We used to run two old small cable systems, all valve equipment, and all thrown out once local relay transmitters appeared :lol:
They used line level cables and resistive tap-off boxes, both were all VHF, and only one included UHF channels, down converted to VHF.
One day we got loads of reports that one of them was down, it turned out some guy had connected himself directly to the main line, shorting it out for everyone else down stream.
We disconnected him, reconnected him properly (and got him to sign a contract!) - but he had to pay to have his TV repaired as well, the front end valves needed replacing to make it work. Presumably due to the high signal levels?.
We were so pleased when we ripped it all out :lol: it was such a pain!.