Mark is on the right track.The ground loop is caused by two seperate grounding points,one for the cable and or satellite and one for your electric.They should both be ground to a common ground stake.If you use a cheater plug and the hum stops you then know it if from the way your cable is grounded.Do not use the tab on the adapter,what you want to do is float the ground.

Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud