If I have the dual output DirecTV dish which is 18 inches in diameter, can I get the ST in HD? Also, if I have the Phase III dish, but only have the possibility of three RG6 cables running to it, can I get the ST in HD?
Yes you will be fine. I had one hooked up with only three cables and I have one hooked up in Myrtle Beach using only 2. Because of the built in multi switch it won't make a difference which port is left empty.