Specific to your request, here is the Signal Analysis:
http://www.tvfool.com/?option=com_wr...ec12c2d759efe3
The antenna is on the roof of our single family home, unencumbered by any near-by trees or vegetation and points toward the west hills where the two main broadcast towers reside.
It is easy to do the proposed test, but sadly, only on the weekend. I do not know what a balun is. The antenna I got from Denny's is this: Denny's EZ HD TV antenna
EZ HD digital TV antenna - Antenna Type: Directional VHF/UHF/FM Digital/HD. I am willing to buy new coax and balun to run this test. (I mean rain is a given here and corrosion is a possibility I suppose.
I do see a warning on Denny's site I had not previously seen. And, as my coax run is MORE than 50 feet, I have to wonder what effect the length has. (But, why does it affect only these channels?) Also I AM splitting 3 ways. (But, all my other signals are 5 green bars - best there is.) Here's his warning:
Signal amplification requirements for the EZ HD antenna
1A. If the coax cable run from the antenna to the TV is 50 feet or less and the TV signals are all rated Digital TV antenna strong signal and a signal splitter is not in use signal amplification will likely not be required.
1B. To receive TV signals rated Digital TV antenna strong signal along with Digital TV antenna moderate signalinstall the AP 8700 preamplifier.
2A. If the coax cable run from the antenna to the TV is greater then 50 feet and or a 2 way signal splitter is in use install the AP 8700 preamplifier.
2B. If any or all TV signals are rated Digital TV antenna moderate signalinstall the AP 8780 preamplifier.
3A. If a 3, or 4 way signal splitter is in use install the AP 8700 preamplifier for signal rating Digital TV antenna strong signal .
3B. If any or all TV signals are rated Digital TV antenna moderate signalinstall the AP 8780 preamplifier.
I'll run the balun, coax substitution on Saturday. Or any other proposals listed here. Thanks for the recommendations. I am open to added ideas to try, in case corrosion is not the problem.