OK, an update. I went by Home Depot today and got 100 ft premade spool of RCA branded RG-6 coax cable. After my wife retired for the evening, I brought the antenna out of the garage and proceeded to try some tests. Also, the coax cable going from my pre-amp to the TV is a known 3ft coax cable provided earlier by Comcast.
First, I decided to try hooking up the antenna to the analog input on my TV to see if I could bring in the stations in north Nashville at all. First, I disconnected the pre-amp from power and ran through the stations (ABC, NBC, CBS, PBS, FOX, WB and UPN). ABC and PBS came in pretty well considering how crappy analog TV looks in general on a modern HD set. Keep in mind that the CM 4228 antenna isn't even rated for VHF stations, so a VHF antenna could obviously do better. But ABC and PBS are close to me...not a hard test. NBC was looking pretty miserable. CBS was non-existant and all other Sinclair UHF stations weren't discernable either.
So I plugged in the pre-amp. At this point, NBC came in a lot better. And I learned something about multipath...it was generally bad in my house...not surprising since I live in an area surrounded by hills and fairly close homes. As I turned the antenna completely around, I discovered I got better pictures if I aimed the antenna directly at any of my neighbors homes. ABC and PBS did not benefit from the pre-amp...not surprising since their tower is so close.
Then I went to the Sinclair stations. I chose WB-58 first since it had a "picture"...and that was using the term loosely. The signal was generally crappy all around with lots of snow, but recognizable audio. Turning the antenna in different directions got similar results to aiming at Channel 4...multipath reflections could be picked up and used in analog mode, even pointing in the opposite direction of the tower where my neighbor's house sits to the south, and further beyond that the hills of Edwin Warner Park. After a while, I found directions that got a picture, but a pretty horrid one.
FOX-17 and UPN-30 were about the same...discernable with the pre-amp plugged in but generally crappy snowy picture all around...not encouraging for a digital lock. Turning the antenna got pretty much the same results as dealing with Channel 4, only that picture was a lot clearer.
One surprise was CBS. I wasn't expecting to see any results given the distance and the lack of a good VHF antenna, but the CM 4228 brought it in anyway...with better quality than the Sinclair stations, but not as good a quality as NBC. But we all know that digital CBS in Nashville is no where near the power of analog CBS, so I can't use that as a predictor.
One more experiment I tried was raising the antenna closer to the ceiling (12 ft) to recheck the interference I was seeing the other night. Sure enough, all northern channels immediately lost most of their signal, meaning I do likely have some metal in the roof of the next room of my house to the north, which is about at the level I had the antenna.
So I unplugged the antenna from the analog connection and went back to digital. I decided to try Channel 4 again. Although I could get a lock to the station, I noticed that the rotation angle that I could get the station was very limited. The range was about 15 degrees or so almost due North....strange since the station is 33 degrees to the north east. Due north is also another neighbor's home with a higher roofline...go figure. FOX, UPN, WB and CBS were all no shows regardless of the antenna direction...not surprising but disappointing.
Last I checked for hot and old spots. And again, HDTVprimer.com was right on the money. Switching back to digital Channel 4, I noticed that there were certain parts of the south side of my theater room where I would lose Channel 4, but regard it again when I walked the antenna north.
So I look forward to testing the antenna again outside to see what the gain difference is. I'm also debating about going back to Randolf and Rice to get the CM 7777 pre-amp since it can do 3 dbs better in the UHF department and .2 dbs better in the noise department than the CM pre-amp I'm using now. Given what I'm seeing, I probably need all the help I can get.
And as usual, I appreciate suggestions from the group.