[ADTech]

Before doing anything else, perform the simple test I gave you by adding some insertion loss to the input of the tuner.

The difference in gain between the C4 and the 91XG at channel 33 is around 3 dB. Cooling the incoming signal from the 91XG down by 3.5-4 dB will be enough to tell if the extra gain of the 91XG is causing the problem or not.

You can expect that filter to run somewhere around $125-150. Therefore, it behooves you to do some preliminary testing to see if it's needed or if you have other issues that first must be resolved. I've hate for you to drop that much cash only to find out later that you need to do something different.

Keep in mind that the 91XG is far, far more directional than a C4 with about half the beamwidth. Aim that was "good enough" for a C4 may or may not be good enough for a 91XG.