Forgive the stupid question but I'm connecting my panasonic GT30 for freeview and see from the manual that I need to use the rf adapter supplied between the rf cable and the tv.My question is why? What does it do? It simply has a standard rf male connector and one end and a female one at the other and so doesn't change the connection. Why not just plug the rf cable directly into the tv?Am I missing something simple here? Any help appreciated.