A prime focus antenna like your 8" C-Band dish is not optimal for Dish Network. First of all, Dish Network broadcasts from two different "arcs" the Eastern Arc, made up of satellites at 61.5 and 72W, and the Western Arc, consisting of satellites at 110, 119, and 129W. Your big dish would only be able to "see" one orbital slot at a time. Furthermore, it is not optimized for KU signals. You would be much better off using the standard Dish Network provided antenna with the multiple LNBFs. Or using multiple 18" or larger offset dishes. Offset antennas are usually used for KU band because they are designed to be more efficient than a prime focus antenna, like your C-Band dish, where the feed is centered in the middle of the dish. You would likely get poor performance out of your big dish, if you could even rig it to work with a circular KU band LNB that can receive the 12.2-12.7 GHz band.