You have no need to use the External Link feature.
The DMR-EX85 has a built-in Freeview tuner, so just highlight the program you want to record in the Guide (big green button on the remote) and set the timer by following the on-screen instructions.
Then you can forget the DMR-EX85, just turn your Goodmans digibox on and select a different channel on that.
External Link on the DMR-EX85 (and similarly the DMR-EX75) is more for use in conjunction with a Sky box, since the Sky channels are not built into the DVD / HDD recorder.
Hope that helps.

__________________