Press Menu twice and you'll see the SysInfo, it will tell you what kind of equipment you have. For a dual tuner (625) to work with a single cable you need a DPP Twin LNB. If you have just a DP Twin or a Twin you'll need two cable runs to drive the dual tuner.
What in the world? why is my post first? Strange...
What in the world? why is my post first? Strange...