I recently posted a thread in GQ about poor TV reception. Yesterday I examined the antenna connections and found that the “matching transformer”–connected to the aerial at one end with wing nuts and to the coaxial cable at the other end–was badly corroded. (This was only ten months after I had bought and installed it.) I replaced the corroded connectors and remounted the antenna to the shed wall. The TV reception on all the channels is excellent now. 
What I want to know is: Why would this make the reception poor on only one or two channels, and not affect it on others? (Last week Channels 2 and 9 had been bad; this week, before I replaced the corroded parts, only Channel 2 was bad.) The salesman at Radio Shack, where I had bought the matching transformer both times (the same store, in fact), had no clue. :rolleyes:
Generally, it has to do with the relative strength of each station’s signal at your house. Due to things like transmitter location, output power, frequency of the signal. orientation of the antenna and other factors, some signals are stronger than others. I’m betting that if you completely disconnected your antenna and turned on the TV you would get passable picture and sound on some channels, and weaker signal on others (probably 2 and 9).
Fat Bald Guy probably has it right.
I don’t know what the relative strengths of the signals are at your place, but when you start to attenuate the signals by having corroded connections, you’ll lose the weakest signals first. If those were 2 and 9, there’s the answer. There’s probably no way for you to work out independently which ones were the weakest, though.
Last week, when 2 and 9 were bad, was it by chance wetter than this week, when only 2 was bad?
No rain at all. It’s likely to rain maybe later today, or tomorrow, although it rarely rains around here after April 20.
You can use a special gel to protect the connections or just plain vaseline. That will make a big difference. I also use it to protect bolts and other metal parts.