I would not use 'usual' coax connectors because satellite and cable boxes use a connector called an F connector. This is partly because Satellite systems have power running down the coax. Next if you wire the extrension wrong you can blow your Sky box. So I recommend that you ignore the previous post and and go to Homebase. There you can get a prewired extension cable that can be used extend your Sky Cable. Make sure that you get the SATELLITE version NOT the 'usual' one.
Terry
October 2006