Adam sounds like he has it spot on.
The original poster sounds like he is using a Dish receiver which offers a modulated (channel 3) output of the content. This can be played back on any television which has a built in NTSC tuner, as most still do.
If that's the case, then the OP should look to see if the TV he is feeding that signal to has audio outputs. Many TVs do, and that could be fed to his new A/V receiver.
If the TV does not have audio outputs, then something as simple as an old school NTSC tuner may do the trick for him.
Certainly, if this is a nice room, with a nice TV, and decent surround sound, then an additional Dish receiver makes a lot more sense.
I'm struggling to figure out how he properly got a coax feed from the main unit to a secondary location. That's not 'normal' wiring for coax in a home.