If your HDMI cables are too short, what can you do?
A fairly common problem that arises with the advent of HDMI (High Definition Multimedia Interface) becoming the new industry standard for transmitting TV signals is how to select the correct length HDMI cable. In the old days, when everything was carried over RG6 coaxial cable, it was possible to run the signal over quite long runs and then just cut the cable to the proper length and put in a coaxial connector and just plug it into the TV. Although the RG6 cable is still used to connect the satellite dish, for example a Freesat + receiver, the output from the box to the TV will now invariably be an HDMI cable.
Another complicating factor is the popularity of hanging flat screen televisions on bare walls or over a fireplace. Obviously no one wants HDMI cables nailed down the length of the wall, so the cables are invariably buried in the wall and typically run from the TV to a nearby built-in unit that will house the satellite receiver. What causes the correct length of cable to be selected is that it is not possible to simply extend or shorten the cable. In general, there is a good selection of HDMI cables ranging from 1m to 20m, the upper limit being due to the level of signal loss that occurs in cables that are no longer than 20m.
No matter how well you plan it, there is always the possibility that the cable is too short. For example, the HDMI input on your new HD TV is in a different location than you expected, or you decide to mount the TV in a slightly different location. There are 2 options when it comes to extending an HDMI cable.
The first and simplest option is to simply use an HDMI coupler that comes with plugs on both ends into which to insert HDMI cables. This option is inexpensive, compact, and requires no power supply. However, it is only suitable for use when the combined length of the 2 cables is less than 20m.
The other option is to use an HDMI repeater, which is a powered unit that ties 2 HDMI cables together and also boosts the signal. Normally, this unit is used when combining HDMI cables where the combined length is more than 20 m. The need to have the unit plugged in and its cost are certainly problems, but this is an essential unit on very long runs.
One final note on HDMI cables is that, in general, in short runs, the difference in signal loss between a low-cost HDMI and an expensive one is quite minimal. Where it pays to spend the extra money is on long runs of cable. Most of the cost-saving HDMI vendors do not make inexpensive cables that are longer than 5m or 10m.