I just installed diplexers so that I could tie in my newly purchased antenna (which is on the roof next to the Dish receiver) and have the OTA signals join the Dish signals in one coax cable. One diplexer is on the roof and combines the antenna and Dish signals into one. Then another diplexer inside splits the signals so that I can route to the Dish tuner and to my HDTV's antenna slot. The antenna is working great because I get crisp, clear OTA channels. But when I use my remote to switch over to satellite to view Dish channels, I do not get any channels - the tuner is searching for satellites to get a signal. But as soon as I disconnect the RG9 cable from my HDTV's antenna slot, Dish channels work. So it seems Dish won't work as long as the HDTV is connected to the antenna. Has anyone heard of this before? Do I have a faulty diplexer? Any help/advice would be appreciated. I can't imagine the usefullness of manually connecting and unconnecting the RG9 cable to my HDTV's antenna slot to switch from Dish to OTA. - Thanks. Paul.