This is a fairly common practice that I see as a Aerial Fitters Preston. Often people will do some DIY on the coax cable and attempt to split the single cable coming in into more than one feed. There are plenty of coax splitters available for coax inputs that are very easy to put together. Sometimes, depending on the strength and quality of the signal this can be a quick and cheap way of bringing in more TV points into the home, although you are often left with the problem of hiding the cable going from one room to the other.
This method hits problems when the quality and strength of the signal is not too strong and is barely enough for one TV let alone 2 or more. There are few ways of gauging the signal strength with out using a meter of some kind. I use a spectrum analyzer that can measure the strength and the quality of each of the transponders or multiplexes being picked up by TV Aerials. I recently was called out to a house in Preston where the owner had done exactly as has been described. She said that they never had a great signal from it but it did work OK with occasional picture fracture and glitch.
The main reason why she’d called was not for the poor aerial signal quality but for an aerial repair service due to the aerial mast falling off the bracket on the chimney. Once I had replaced the old chimney bracket with a new one and mounted the mast on it I went inside to test the signal. Its there that I noticed the diy splitter going to 2 TV’s and I wondered whether or not there would be enough of signal for the 2 TV’s. I tested the signal in which read around 58 – 60db coming in. but once it was split the signal going to the 2 TV’s went down to between 44 – 36db, which would cause a picture break up, fracture and glitch, particularly when the weather is poor.
The best way to split the signal is as near to the digital aerial head as you can, which is usually around the base of the mast. It’s also the easiest place for the splitter to be fixed. When the signal is split nearest the TV Aerial, then there is a lot less of a loss than when it is split further down the cable where the signal is already feeling a loss. However, due to this customer living in rented accommodation she didn’t want to spend too much, so the other solution and also the easiest is to put the cable into the property straight into a distribution amp or aerial booster. This then splits the signal at no loss to the out puts. She went for this solution and once installed was happy that not only were her TV’s back up and running, but they were no longer suffering with picture break up.