I am currently in a temporary rental and I can't run extra coax wire where I would like and I need to solve an OTA input problem. I have done quite a bit of reading on other posts and didn't quite find my answer. I would like to diplex in an OTA HD signal to connect to the antenna input on the back of my HR20-700 for local HD stations (and even to the ant input on my plasma). I only have one RF-6 coax running from a central location (this location has both the Directv coax and the available OTA signals) to my tv & receiver. At the inside where the TV is is a PI-21 power inserter, on the roof is a new slimline dish. I would think I could buy 2 diplexers and install them inline on the main coax? But I don't know exactly where to put them. One diplexer after the PI-21 or before? Second diplexer at my central location? Could someone explain exactly where to go with them.... Thanks in advance!