Problem disturbing analogue TV around house

dominoman

I am having a problem disturbing analogue TV around my house. I have the following equipment (See attached picture)

Roof aerial with masthead amplifier
Power supply for masthead amplifier.
TV Cable down to main room from power supply for masthead amplifier.
Cable from aerial to FTA satellite box
Cable from FTA box to SKY+
Cable from rf2 on SKY+ to SLX8b distribution amplifier


The problem I have is that the analogue TV works fine downstairs from either RF1 or RF2 on sky+ but I cannot watch any channels on the other TVs when the aerial is connected there is some sort of picture but with 90% interference.

If I disconnect the aerial lead I can watch SKY+ and the FTA satellite with a perfect picture in all rooms. I reckon when the aerial is connected the SLX8B over amplifies the signal from the TV and is blocking all channels. What do I need to correct this???

marclt

dominoman wrote: »

I am having a problem disturbing analogue TV around my house. I have the following equipment (See attached picture)

Roof aerial with masthead amplifier
Power supply for masthead amplifier.
TV Cable down to main room from power supply for masthead amplifier.
Cable from aerial to FTA satellite box
Cable from FTA box to SKY+
Cable from rf2 on SKY+ to SLX8b distribution amplifier


The problem I have is that the analogue TV works fine downstairs from either RF1 or RF2 on sky+ but I cannot watch any channels on the other TVs when the aerial is connected there is some sort of picture but with 90% interference.

If I disconnect the aerial lead I can watch SKY+ and the FTA satellite with a perfect picture in all rooms. I reckon when the aerial is connected the SLX8B over amplifies the signal from the TV and is blocking all channels. What do I need to correct this???

Sounds to me as though your signals are being overloaded. As you already have a masthead amp, this will be amplifiying the signal - then when you put it through the distribution amp you are boosting those signals even more! In order to counteract these problems you'll have to get an attenuator. Quite a little and relatively cheap device to fit. It should reduce any problems you have and you can get adjustable ones also to reduce the gain.

By the way, what channels do you need the masthead amp for?
If you can screen grab (or take a photo of) the interference then it might help diagnose the problem. Overloading causes an image to be overlaid onto the one you're watching with a rolling effect...

dominoman

HI marclt,
Not an expert but without the masthead amp powered on I get no analogue pictures. With it I get BBC1, BBC2, ITV,CH4 and the 4 irish stations. I will see if I can post a picture of the interfrence.

If I get an attenuator would I fit it before the satellite boxes or after leaving the SKY+ box.

marclt

dominoman wrote: »

HI marclt,
Not an expert but without the masthead amp powered on I get no analogue pictures. With it I get BBC1, BBC2, ITV,CH4 and the 4 irish stations. I will see if I can post a picture of the interfrence.

If I get an attenuator would I fit it before the satellite boxes or after leaving the SKY+ box.

If your signal going into the sky box is clean, then i would fit it just before the distribution amp. If you connected one of your other tvs directly to the rf out on the sat box, and the signal is good, that will isolate your problem to the amplifier box.

Then an attenuator would be your best bet. I'm presuming that you have two aerials one for UHF UK Tv, the other for UHF Irish tv? If you have a combiner it may be possible to adjust the level of signal going into the combiner for the Irish channels - as these are more than likely causing the overloading, given that you are closer to the Irish transmitter than the UK one.

Let me know how you get on?

maxg

It looks more like dominoman broke the 1-5-9 rule for analogue channels with setting the rf output channels of the receivers to the wrong uhf channels.

Antenna

How many TVs is the distribution amplifier feeding? If just 2 or 3 try using a passive splitter instead of the distribution amplifier (good quality one - metal not plastic).
You might have plenty signal on the RF2 out and no need for a distribution amplifier anyway?

It could well be that there could be non-TV signals - such as a very near 900MHz mobile phone base station overloading and swamping the distribution amplifier too!

marclt

1-5-9 Rule.. in some places you just can't help but use any free space you can get...

I agree with you antenna... if the signals are strong enough then a good quality splitter would work also.

byte

Those SLX amps can be rather fussy alright, and don't like too high levels going in. As it's an SLX8B, I presume it's needed to power "Sky eyes" TVlinks too.

As already mentioned, a variable attenuator should do the trick with little expense.

maxg

marclt wrote: »

1-5-9 Rule.. in some places you just can't help but use any free space you can get...

Some times you have to switch on your brain.
http://www.kat5.tv/taboo.html

http://www.automatedhome.co.uk/TV/Taboo-Channel-Calculator.html

Antenna

the OP says ALL his channels are bad. The taboo channel issue would only affect certain channels.
That www.kat5.tv website you link to is a seller of a AV distribution system and it seems like it is doing all it can to put people off using RF modulators!
5 channel separation is unlikely to cause problems with modern TVs, but that page says it definitely will!
9 channel separation will hardly cause problems if the higher channel is about the same strength, or weaker than the lower channel.

The OP hasn't said what happens if he disables the 2 modulators? Is there still a problem with the terrestrials through the distribution amp?

maxg

The OP wrote he get no channels without his masthead amp.
If the distribution amp is able to overload the signal the masthead amp must be 30db or 40db.

dominoman

Hi Folks. An attenuator has sorted the problem. All channels now coming through clear. I needed to fit it before the sky+ as it will not let the return signal pass back from sky eyes to the Sky+ box.
marclt. I only have one aerial as it picks up all the channels fine and maxg I already had the channels separated out correctly as I could view them before going through the SLX8b.
Anyway thanks for all the help and suggestions folks.

maxg

In such a case you didn't write all facts.
I guess you only unplugged your masthead amp and didn't try it without.