I had a very similar thing happen to me when we first got the trailer.
To make a very long story short.
One of the cables had come loose in the wall.
We have a Selector wall plate with a bunch of switches on it.
On my rig it's the same spot the antenna amplifier is located.
Here is a picture of what I am talking about. http://i284.photobucket.com/albums/l...2/IMG_2036.jpg
(This view is from the backside due to a remodel I was doing)
I removed the two screws and was able to pull the whole unit out about 4-5".
Here is where I found the problem.
Whoever crimped the connectors onto the coax did a poor job and the cable had completly pulled away and was just dangling there.
To get to the other end of the cable I had to remove the TV and then remove the box directly behind it that houses the Power, Audio, & Video connections that the TV plugs into. (your model may be different)
Every one of the connections was lose and poorly crimped.
A trip to radio shack for some new connectors and coax solved the problem.
If you have to go to this extreme, you might as well replace the cheapo splitter while you're at it.
I haven't had a problem since.
I hope this is helpful.