In reference to the hum problem caused by the cable system I did an internet search and found a suggestion of putting in a 75 ohm >300 ohm > 75 ohm interconnect in the cable between the wall where the cable comes in and the cable box and guess what? The hum disappeared.

This may not be an ideal solution according to the suggested solution because there is limited band width and if I go to HDTV in the future it may cause a problem but for now the hum is gone.

John