+1 on the drop isolator recommended by @jea48
I don’t have the Jensen, but I do have an Extreme. When I traced a hum to my cable line, the cable company (Cablevision, Long Island) installed an Extreme drop isolator http://www.extreme-broadband.com/hardware.html and the hum was completely gone.
Edit: My cable company provided the part and installed it free. Also, I was told there is no degradation of the picture/sound quality, nor did I detect any degradation. I think this is one of those "can't hurt and can only help" kind of parts.
I don’t have the Jensen, but I do have an Extreme. When I traced a hum to my cable line, the cable company (Cablevision, Long Island) installed an Extreme drop isolator http://www.extreme-broadband.com/hardware.html and the hum was completely gone.
Edit: My cable company provided the part and installed it free. Also, I was told there is no degradation of the picture/sound quality, nor did I detect any degradation. I think this is one of those "can't hurt and can only help" kind of parts.