Hi

My set up at home is this:

TV aerial -> Masthead amp (poor signal area) -> youview box -> RF out -> RF modulator IN (youview uses modulator to send round the house -> Modulator rf out to Sky aerial in -> rf 2 to global amp then down to 3 other tvs.

I'm picking up a huge amount of interference on all rf channels except 21 (which my sky box uses) but i cant seem to find one for the modulated youview signal to use. I tried removing the aerial in from the rf modulator to isolate the tv signal and all the interference stops so its clearly coming from the antenna on the roof. I'm assuming the mast head is picking up channels from distant transmitters as my youview box and tv's are full of channels in the 800's. I'm limited to what hardware i can use as i don't have power in the loft.

Can anyone suggest any ideas to let me send the sky channel, youview channel and also freeview round to all my tv's without this issue.

I hope that makes sense.
My transmitter is Waltham.
Ben

Hmmm. If you are in a poor signal area that needs a masthead amplifier to get a usable signal then that would suggest you should not be getting loads of distant transmitters at any sort of level to be received by your TVs etc. Usually a masthead amplifier is used where the main transmitter is marginal and you need a bit of a boost to overcome losses in the cabling etc which should mean any even weaker signals from more distant transmitters should be down in the noise.

How easy would it be to bypass the masthead if only for testing? That should eliminate any possibility of distant transmitters causing interference.

Also try setting the RF modulator to a channel over 60. There are no TV services broadcast in that range now so there should be less chance of interference. However the TVs should still tune in to anything up to channel 69.

Bypassing the masthead would be as easy as just joining two bits of coax so I will give that a try. Over 60 don't I have the issue of 4g to contend with though?

Only if there is a 4G 800MHz band transmitter somewhere within range of your aerial. Not all 4G is 800Mhz so you can't always rely on a 4G mobile indicating it's got a 4G signal as meaning there is a potential for interference.

And if there was a high power 4G 800MHz band transmitter nearby then there is a very real chance it could be causing you problems already. if the signal were strong enough it could cause overloading in the masthead amp leading to problems receiving the Freeview services cleanly.

If your problems with reception have only started recently i.e since last summer then before you go cutting up bits of cable, I'd investigate the 4G angle a bit.

If you've got a 4G transmitter in your line of site then it could well be causing the issue - you can look at the at800 website for more info.

This week I finally put 2 & 2 together with regard to some problems we'd been having with some channels - when I contacted at800 they confirmed there was a 4G transmitter in the locality which was likely to be causing the problem and are sending a filter out - if you can't be bothered with that - then you can pick up a 4G filter from a well known auction site for £ 5.

If you decide 4G isn't the likely problem then you'll need to work through it logically..

One observation, you say you've got a masthead amp - which presumably is powered? Is that power source the same as the global amp or is it something else? If it's something else, then effectively you've got more than one amp in the 'circuit' which may also be causing you a problem.

The global amp is for the magic eyes in the sky box and is powered by the rf2 output in the back of the sky box. The mast head is powered by a psu in the lounge. As for 4g the only operators in my area offerin 4g is EE and Three. I have an ee mast about 300ft away but as far as I know that's not offering 4g at the moment but can't be sure. There is a Vodafone one behind my house (about 600-800m away) but that's not offering 4g at present as far as I know.

A quick check shows only 1800 and 2100 MHz transmitters in my location.

As I posted 4G is only an issue if it is in the former 800MHz TV band. There are other frequency bands it could be using.

Can you just clarify something? You say you get interference on all UHF channels. Just exactly what do you mean by this? Do you mean that no matter what channel you tune the UHF modulator on the YouView box to the resulting signal has some sort of interference on it? And only the YouView modulator is affected by this interference. Or that you get interference even on Freeview channels?

If it is only the YouView modulator that is suffering interference then it is less likely to be anything like 4G. That would blatt out anything and everything including Freeview.

what I mean no matter what channel I set the sky box to output an rf signal to or no matter what channel I have the rf modulator outputting to the analogue picture is poor ion every extra tv. Remove the freeview signal from the setup and everything is perfectly clear on every channel

You may be overloading the modulator input, if the amp is variable try turning down the gain. If not fit a variable signal attenuator. to the modulator input

http://www.screwfix.com/p/vhf-uhf-va...questid=224119

Where would that be placed?
Thanks for your help guys by the way

You just plug it into the modulator input socket at one end and the aerial in to the other socket on the attenuator. It will only fit one way.

Perfect, turned down the gain on the mast head right to the bottom so it's only just on and bingo works perfectly. Thanks a lot guys

You place the attenuator on the output of the masthead amp power supply before it plugs into any of your kit.

Though for the time being you can get a very similar effect simply by bypassing the masthead amp. That would tell you if the problem is excessive aerial signal or not. Plus if you continue to get perfect Freeview signals with the masthead bypassed you could take the amp out of circuit permanently.

Though check the signal strength on the TVs. If it is below 50% and especially if it is 30-40% without the amp then you may have problems with noise interference. If so then maybe try a lower gain amp or the attenuator.

If the signal is over 50% then you might get by without the amp at all.

Edit.

See you've more or less done the above. But I would still check signal strength on the TVs just to be on the safe side.

The signal on my youview with the gain on low is 50% goes up to 65 with gain on mid to high. The other TVs are showing 46%. Quality on all sits at 100%

I used to get 45-50% signal on Freeview at one time and didn't have any real issues. But at least you may have a bit of gain in hand if you need it. Just have to suck it and see how it works over the next few days and tweak as necessary.

Yeh I'll monitor it, mainly watch the ip channels anyway. Again thanks for all your help.

Just did a rescan now the gain has been reduced and helpfully it has also cleared out the 800 channels