Ok Ive finally decided to install My antenna/preamp/rotor.

I live in zip code 61115. My question is do I need a FM trap? Should I set this to in or out on y CM 7777?

You only need it on if you have interface from locally strong FM stations.

Ok Ive finally decided to install My antenna/preamp/rotor.

I live in zip code 61115. My question is do I need a FM trap? Should I set this to in or out on y CM 7777?
If there are any FM radio signals that are rather strong as compared to the TV signals you are wanting to view, set it to in. If the FM radio signals are coming from the same locality and you want them, set it to out.

If you're not sure, set it to out and check your TV channels. If they re fine, leave it as is. If you see garbage in the pictures, set it to in and take another look at pictures.

Ok I will give it a whirl at in. If I do not like the results Should I rescan the channels after the switch?

you are rather close to the towers for a cm7777. the cm 7777 will most likely have too much gain for your setup. the fm switch will not do much good if the gain is too high.

how to tell if you have overload...try the setup first without the amp and get a signal level reading. if the level drops aimed at the towers and goes up as you aim away you are experiencing overload.

* yellow - uhf WTVO-DT 17.1 ABC ROCKFORD IL 236° 8.2 16
* yellow - uhf WQRF-DT 39.1 FOX ROCKFORD IL 236° 8.2 42
* yellow - uhf WREX-DT 13.1 NBC ROCKFORD IL 250° 11.0 54
* yellow - uhf WIFR-DT 23.1 CBS FREEPORT IL 240° 7.9 41

the cm7777 is generally not suggest with towers coded yellow and less than 30 or so miles away. you may want to exchange the unit for an winegard hdp269 preamp (if you actually need one there) which is more appropriate for your situation.

Look at reception of the analog channels, especially in the VHF range (2-13). If you see "herringbone interference" (lots of dancing chevrons...the kind like on an army uniform, not the gas station), that moves to the beat like music or voices, that's FM interference.

All it might do to the Digitals, is make them intermittent, or un-find-able.

Hey thanks for the advice. The reason for the Preamp was to recieve Chicago and Madison channels...not Rockford. Of course I dont really want to sacrifice Rockford if I dont have to. I think Im going to tackle this job tomorrow. I will let you know what I find.

If you get overload it will actually affect the distant channels more than the local ones. As pointed out above it will make digital channels intermittent or not receivable. So even for the more distant channels you will most likely be better off with no preamp or the lower gain preamp.
John