My RG6 cable runs from the roof 80 feet down and unions to another cable that runs to my main room 80 feet of cable away. Maybe it is even longer as I didn't wire the building myself. The 622 sees the dish antenna just fine over this setup, but when I try to diplex an outdoor HDTV OTA antenna in to the Dish Network stream and back out I get zero signal for OTA. Any suggestions? When testing from the roof I can get 90db signal strength, even with a couple of diplexers in and out of some short cable lengths. If I haul the antenna down next to the 622, I get strong signal, but the walls are so thick that the tall buildings create a very different directional signal path for each station. Not to mention that the antenna is too big for the room. I have tried a 10db amplifier by the tv (which I was glad didn't mess up the Dish Network) but it doesn't improve the OTA either. I thought about trying a 25db amp, or moving the amp to the junction halfway between the dish and the receiver or even on the roof. Is there an easier way to debug this? What are the possible causes of signal loss? This isn't a specific to the 622. None of my devices can see the diplexed OTA signal.