I have to start at 120 these days, i can't get a worth while picture when combining with cable lower than that. Plus I hate to have to go rearrange the modulated channels when the cable company decides to change their ordering. I then have to modify the modulator settings, reprogram remotes, and reteach clients. Sometimes I do get older tv's that can't go that high, i just show the client what it would look like if I place the signal on channel 80 or so and they agree, put it on 120 and they will get a new tv.

As for the origin of this thread, I find most modulator picture problems come from over amplified signals, they get juiced up in the modulator, then sent through amps, then run thirty feet and are way to hot. Try hooking the ouput directly to one RG6 directly to the tv, see if you have a decent picture, and then add you cable signal, amps etc, until you discover which piece is causing the problem.