If you want to add an extra television aerial outlet for a set in another room, the esasiest way is to use a splitter on the main aerial where it comes into the house. Some signal loss can occur with these, so you may wish to consider an amplifier model instead. These will split the signal to two or more outputs and amplify the signal at the same time. Generally these are powered by a 13amp plug so you will need to locate it near a socket outlet.
Routing the coaxial cable
Lay a new coaxial cable from the point where you intend to position the new splitter or amplifier to the location of the new outlet. The cable can be run externally or internally depending upon the layout and position opf the two points.
To run the cable externally, for example from the living room to a bedroom above, drill a hole through the wall near the main point and pass the cable through. Run the cable up the wall and use cable clips to hold it firmly in place. The holes can then be sealed around the cable to prevent any draughts.
To run cable internally, use a similar method to that used for laying power and lighting cables under a floor. This will make the finished job more discreet but will require floorboards to be lifted to gain access. Alternatively, coaxial cable may be surface mounted and the tidiest way to do this is usually to run it along the top edge of the skirting board neatly fastened with cable clips.
Prepare the new television aerial outlet
This may be either a surface mounted or a flush television aerial outlet. For flush mounted boxes, the process of installing is similar to that of Socket Outlets - Fitting Flush Metal Box article. Prepare and fit the mounting box as detailed there. Surface mounted aerial points can simply be fixed to the wall at a suitable place once the coaxial cable has been connected.
For flush mounted outlets, feed the cable into the mounting box through the hole making sure that this is protected with a grommet to prevent damage to the cable.
Connecting the coaxial cable
Trim back the outer sheath of the coaxial cable. This may be done by slitting the sheath with a sharp knife, folding it back, and trimming. Alternatively make a shallow cut right around the sheath 25mm from the end and pull the end piece off. Push the outer coaxial wire mesh back from the inner core leaving around 20mm exposed. Now cut into the inner core insulation in the same way to leave 15mm or so of the central coductor exposed.
Feed the cable end through the retaining clamp and insert the conductor into the terminal. Tighten the terminal screw. Make sure that the outer mesh is not touching the inner conductor at all as this will interfere with the signal. Push the mesh back if needs be and secure this with the cable in the retaining clamp.
Fix the surface mounted outlet back to the wall using the fixings provided. In the case of flush mounted, carefully push the faceplate back against the mounting box ensuring that the cable isn't trapped or snagged and then fasten with the screws.
At the splitter or amplifier end, fit a coaxial plug to the new supply cable and insert into the appropriate outlet. Remove the aerial signal input lead from the main televison and connect this to the splitter input socket. Connect the television with an aerial lead to the appropriate outlet on the splitter.