Interference when feeding Sky to a second TV
Question submitted online by Ken:
“I have connected a sky+ box to a second tv with quality coax and it works OK, but I am getting faint diagonal yellow/green lines on display”
Our Answer
To get the signal from a Sky box to a second TV set over aerial cabling, the Sky box does something to the signal that’s called “modulating”. The signal from a modulator that’s sent over a longish cable run is newer going to be as good as a SCART or HDMI connection, and in a lot of cases, you will notice reduced picture quality.
There are a few things that you can try to improve picture quality when sending a feed from a Sky box to a second room.
Try a different channel
The Sky box creates a new TV signal on a channel that your second TV can tune into. This is called “modulating the signal”. The Sky box uses Channel 68 by default, but if you’re setting interference, it’s worth trying a different channel, in case it’s another TV channel that’s causing the interference. Experiment with a few different channel numbers until you get one that works well.
For details of how to change the RF channel, see our question: How do I use the Sky RF Output?
Reducing interference
One of the common causes of a drop in picture quality is interference, commonly from mains electricity, or from equipment that transmits RF (radio signals). The interference makes its way into the co-ax aerial cable, and the signal is affected.
Here are some things to try:
1. Make sure the aerial cable is as far away from mains cabling as possible
2. Make sure the aerial cabling is as far away from anything that transmits radio signals as possible – such as wi-fi equipment, Bluetooth devices, baby monitors, mobile phones, cordless phones, etc
3. Make sure that the aerial connections are OK at both ends. The plugs should be correctly fitted with the shield and centre pin making a good connection
4. You’ll get best results using high-quality low-loss co-ax aerial cabling, as well as well-made co-ax aerial plugs
5. You should ideally have a single run of co-ax cable (i.e with no joins). Also, don’t have the cable any longer than is necessary
6. You could consider reducing interference by winding your aerial cable through a set of Ferrite Rings, which can reduce some types of interference. Ferrite Rings are available cheaply from Maplin.
Ferrite Rings, used to reduce interference on cables
Other Solutions
If you still have problems, there are a couple of other alternative ways of getting Sky to a second room:
1. Consider a wireless AV sender. These use radio waves to get a picture to a receiver in another room. They don’t reply on aerial cable. See the range of Wireless AV Senders at Maplin.
Pair of wireless AV senders
2. Get Sky Multiroom. Sky will fit a second Sky box, which will enable to you watch a different Sky channel in a second room, making for better viewing choice, and better picture.
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