I had a situation at home where a bad coax signal splitter was introducing a lot of noise to a TV. You might have something similar and it is fairly easy to check. If all your TVs are about the same, check close to where the cable enters your house.
I've had good luck with the "Ideal" brand at Lowes.
HTH a little. Good luck.
(Who lived in a place where the phone would go out whenever it rained. It took over a year for them to fix the wiring on the pole for that, so he feels your pain.)