I have a commercial UHF/VHF Yagi designed for TV reception, also used for 2 meter reception, that has been installed for years but seems lately there's increasing amounts of signal disruption.
I have a grounding block on the antenna coax near entrance to the structure as recommended. The ground wire for the block runs to the service panel, where it is connected to a ground point for the structure. I estimate this ground wire run is at least 30 feet. The mast is also grounded by a separate ground wire going to same service panel.
Is this grounding block with the long ground wire affecting my signal? I suppose all sorts of noise is on the structure ground system along with the 30 feet of wire acting as another antenna. My understanding is my antenna has a built-in balun, but I don't know the specifics of what kind of balun this is (if it matters). Do I need to worry about common mode currents on the outer shield of the coax, or does it not matter because of the balun? If I do need to worry, could a ferrite bead on the coax at some point help? If yes, what would the recommended placement be in relation to antenna feedpoint and the grounding block?
This is for the Winegard HD7694P antenna with a preamp installed on the mast. (Yes, it occurs to me the preamp could also be going bad, but that's not my question here.)