Why on earth are you using coax for SNES? I would upgrade to composite at least and many composite cables include S-Video, which is even better if your TV will support it.
The main reason I used coax was that the previous tv only had two sets of RCA inputs that were taken up by a PS3 (back inputs) and either a PS2 or a 360 (front inputs) so I was already sick of popping cables constantly plus the SNES I purchased came with the old RF adapter so I just plugged it in and decided not to care. I already plan to get a different input since the flatscreen is much easier for me to work with physically (that CRT was a beast, far and away the heaviest tv I ever handled) and I can actually get at back inputs without trying the break the stand.

In all honesty, the whole thing was not something I had planned, some crap happened in my personal life and I came out the other side with some stuff that I wasn't planning on acquiring for a while yet but couldn't turn away since it was free and I felt I earned it for my troubles, but the upside is that I didn't plan all this out and learn what I needed to know before I swapped tvs and the 'old' tv did not survive the process (nothing deliberate, the thing decided that it wanted to jump off the dolly I wound up using to move it something like three times, even with straps). So I'm mostly feeling around in the dark like an idiot.