Hi Guys, just want to chime in here and let you know I checked out some stuff. I was just so very curious so I took my little 19" Samsung TV & my DTV DVR receiver out to my rig and gave it a shot.
I plugged everything in and connected coax and RCA's appropriately & then turned on the green button.. got a nice clear picture of the error 775 and a nice graphic explaining that I most likely need the SWM box.. As previously suggested..
This is so complicated for my sleepless brain right now I think I'll call DTV in the morning and get in touch with their tech support.. they were great in the past. I found several types of said boxes but the PDF you provided indicates taking care not to use wrong box or hook up incorrectly so could damage my DTV receiver.. Don't want to do that!