Ok first off I happen to agree with avdude and wonder why 120. However instead of trying diagnose the result do yourself a favor and isolate the cause. Leave the system as it currently is and take the cable feed out of the system. More than likely you will see the distributed Sat signal immediately get better. I would assume that there is digital cable in the area you are which means even though you may not be using a set top cable the channels are actually still in use or reserved. Either way you say you are using a filter for Ch116 is that a choke for 116 and above? Isolate its actual trap frequencies and go from there channel vision has good documentation to help you there. Ok other possible areas of concern would be the way you have this setup at the head end this is based on what I think you are saying. Anyway the cable signal coming in at the board lets say for sake of argument is 15db which trust me it isn't. Then you are modulating a Sat to 120 running at 25-30db trust me it is then on top of that you are amplifying it once again after it comes back out of the combiner. Try either using an attenuator possibly in the sat signal or maybe combine the sat signal after the amps. Best thing I can off is start at the beginning rahter than the end because that is where the problem is. Hope this helps and if I am way the hell off all I can say is I need more info!