TV Aerial interference

[Delboy315]

Three storey house, with an old TV aerial which serves a ground floor TV and digibox. Newly installed cable spotlight system in the attic; when lights switched on the TV signal on ground floor is totally distorted by 'interference'.
By my logic it must be one of three things:-
1. TV aerial (located on roof) is picking up some interference from the light cable system nearby.
2. The aerial cable when passing by the lighting circuit is picking up some interference from that lighting system.
3. The digibox on the ground floor is either faulty (unlikely) or somehow picking up interference from three floors above.

Any experience of this problem would be welcomed as well as a solution please!
Delboy315

 

[electronicsuk]

My money would be on a poor quality SMPSU powering your lights (I assume they're ELV?) with sub-standard filtering that's kicking out all sorts of nasties and upsetting your TV reception. I assume there always used to be lighting in the loft, just not of this type?

 

[Delboy315]

Thanks Matthew.
Yes, ordinary 240v lighting circuit works fine and always has. I don't know what a SPMSU or whatever you called it is. Can you spell it out for a keen pensioner DIYer please?
This is for a friend who lives 100 miles away, but I presume that it has a transformer of some description. Could be the transformer all along?

Delboy315

 

[electronicsuk]

SMPSU stands for Switch Mode Power Supply, and it's the more modern equivalent to the wound transformer. They run at a high frequency and so can emit a lot of electro-magnetic interference if poorly designed, which many of the cheap units on sale today are. If you can find out the output voltage and wattage of the power supply and confirm it is indeed switch mode (pictures would help) then chances are it can be replaced by a wound toroidal transformer. These operate at 50Hz and emit a lot less electrical noise.

 

[TicklyT]

ELV (12 Volt) lights by any chance?

Have you got a TV amp / splitter in the loft that may be picking up interference from the lighting 'transformer' (actually a switch mode power supply) placed a bit too close to it?

Do you receive a good TV signal, or was the reception marginal in the first place? Most DTV boxes will give information about signal strength and quality.

Initially I would try to maximise the physical seperation between the TV coax and any other cabling, then look to either a different 'transformer' or a better quality aerial coax. The average coax TV aerial lead leaves quite a lot to be desired for DTV reception.