Claybuster, what 300ohm said is not a particular negative about +17dBi antennas per se, just a nod to the practical reality of how weak an inherent signal would be if only a +17dBi antenna was capable of picking it up at a given location on a given frequency while no lower performing antenna could. Personally I would never count on such a signal to be stable or reliable, even with such a superantenna, because that +17dBi rig is working on pulling in a signal that is so weak that it is at the very margins of what is possible in the real world. Darn those atmospheric and geographic effects on OTA signals! So, as a wise man once said:
if the signal ain't there, it just ain't there.
As for you particular reception situation, we won't dig into it in this thread since it is already covered in the other thread: http://www.digitalhome.ca/forum/showthread.php?t=200545