Very selective problem w/ HD7694P

[jim_mpls]

I have HD7694P on roof, 25' from ground, 40' of RG6, going to one TV, and a maddening problem with one station--unfortunately the one my family most wants to see. From here in SW Minneapolis, there is a cluster of 7 broadcasters all about 13 miles away, all between 44 and 47 degrees. My PBS station is on phys ch 34 (593MHz) and acc to both tvfool and antennaweb it should have as good a signal as the rest. ALL the others come in with no problem, but the four channels of KTCA (2.1-4) all lock up and pixellate much of the time. All other channels show signal strength of 80-92, with one occasionally dropping to 52 but no recep problem. The problem one's strength is sometimes around 40 but often drops to nothing. The SNR for all the good ones ranges from 24 to 29, but the problem one never gets above 14 and frequently drops to zero. That one can show errors jumping around from zero to 6672; the others never show any. Sometimes the signal seems to be a little more fragile when we're in flight path, or when there's a bit of weather, but no other station is ever affected by either.

Sorry for going on so long, but this station should be in the middle of the pack, but it's uniquely bad. It can't be the antenna, unless this one frequency might be uniquely sensitive to echoes, height, whatever. Any suggestions about how to troubleshoot this thing? Thx

[winegard]

Good morning jim_mpls,

Since the problem is with only one channels try raising the antenna 5 feet or so to see if there is an improvement in the signal level for real channel 34 (2.1). There could be a problem with surrounding trees affecting the 34 signal and you need to find a stronger signal level.

[TomV]

Raising or lowering your antenna may not be practical. However, rotating you antenna from the ideal direction you probably have it at may help out. Since you are so close to the antenna farm, you can be pointing 45 deg away and still get good reception. This could help if you are running into reflection problems from local buildings or the ground. Heck, you may even have an overload issue with your TV since you have so many close-range stations feeding you area.

[jim_mpls]

I can start by rotating and seeing if being off the direct 45 helps. Raising will be harder/more work since it's mounted on a 5' mast supported by a gable end mount. Going up means getting a longer mast, but I could do it if that were the necessary step. I'll try the de-centering off the signal first.

If there were overload, wouldn't I see that in the signal strength or S/NR? Those are both lower for that one broadcaster, but great for all the rest.

The weirdest thing happened last night--don't know if it tells anything. Bad storm with lots of rain, and we were watching different channels for severe weather. In the middle of that, I started checking signals from various broadcasters. All the normally good ones were even higher than usual, some showing SigStrength of "Maximum" and S/NR even a bit higher than usual (32 vs 29). Then, checking my problem station, I found a rock steady picture, Signal Strength of 53, S/NR of 22. In the middle of the rain, everything was better! Weather mostly cleared this morning, and SigStr slightly down but still okay at 48 and S/NR at 17-18 and good picture. Any clues there?

Thanks to both of you for above suggestions. It gives me a couple of avenues to try.

[TomV]

If you state that your reception improved with a heavy rain, that tells me that overload is something that cannot be ruled out. As I suggested earlier, rotate the antenna away from ideal to reduce the signal into the TV. This may replicate the rain condition that attenuates UHF signals.