SAB Explorer - need advice on set-up

TheFrog

I have a SAB Explorer PVR twin tuner which I purchased a couple of years ago. Due to health problems I have only just got around to setting it up in place of my Sedea. I have a motorised system with two LNB's. I have connected the two cables into their correct inputs on the receiver, but cannot figure out how to use BOTH tuners. When I set the timer to record a programme, it will not allow me to change channels, so I cannot watch anything other than the channel being recorded (which is a total waste of time). The handbook (which is quite good in it's way) mentions an RF Loopthrough cable but here is where I am completely lost. Can anyone give me advice please? Most of my hair has gone, so I would like to retain what little I have left! Incidentally I live in SW France.