First off Welcome!!
Your cable coax feeds to the same wall connector as your on the roof ant. The key is make sure your "power boost" is turned off. The power boost switch should be on the wall plate, sm. button. I would also check to make sure the connections are tight behind the wall plate. The people who put the things together do not really tighten them up.
Dish does work, you do not need to look at that system. There are the other systems that will mount on the ladder for around 500.
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