I don't see virtual channel 19.1 on your TVFOOL report. Is it WOIO on real channel 24?
http://www.rabbitears.info/search.ph...pe=dBm&height=
That's a very weak 2Edge signal with a Noise Margin of -15.1 dB with co-channel interference from WSFJ with a NM of -24.6 dB; only 9.5 dB weaker. At least they are not in the same direction.
Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html
-20 to -10dB
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These stations are extremely weak to receive and even the best antenna system cannot guarantee reception but they're not quite as hopeless as the Impossibly Weak category. TV Fool usually shows these stations as "2 edge" which means the signal has to refract over 2 hills or mountains. These paths are easily affected by temperature inversions that make for large swings in signal strength. TV Fool is most inaccurate with weak signals and it may be possible to receive these stations. Reception is not likely to be 100% of the time and in general you should not count on these stations for recording. A low noise preamp is required for any chance of reception. A distribution amp should be used if more than 1 TV will be connected to the antenna.
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A signal must have a NM of 0 or more to be received. You can add the antenna gain to increase the -15.1 NM, that probably doesn't quite give you a positive NM. You can also add the gain of a preamp, but must subtract the Noise Figure of the amp because it adds its own noise that degrades the SNR of your weak signal. But, as you found out, a preamp will be overloaded by your strong signals. The overload creates spurious signals within the preamp itself that harm the weakest signals.
The problem is too much difference between the strength of your strongest signals and your weak desired signal, which is called the Dynamic Range.
If you don't have enough gain for 19.1 without a preamp, but too much with a preamp, it is sometimes possible to find a happy medium by inserting an attenuator between the antenna and the preamp input. The preamp used should have a high resistance to overload.
If that doesn't work, you have to resort to exotic measures (expensive) to even have a chance. An example would be a separate antenna, preamp, and custom bandpass filter for real channel 24. How badly do you want it?
Do you have your antenna aimed at 80 degrees magnetic when trying for 19.1?
You have some strong local FM signals that might interfere with TV reception. You should insert an FM filter in the coax when not using a preamp. If you use a preamp, it might have an internal FM filter. See attachment 2.
