I have a Plasma TV that has for input #3 PC RGB . When I hook up my Audioquest component video cable to it I get no picture. What gives?

Also has anyone upgraded their coax cable running from a Sat. dish to receiver and seen any video improvement?
That input jack is for a computer interface cable not a video line. RG6 cable is the one to have and has replaced the thinner RG59. You want the thicker cconducter cable to avoid video loss on longer runs of up to 100ft.