Freeview breaking up through RF2 sky box output.

donegaljoe

Standard Member
Hi folks,

I will try to keep this as simple as possible, I have four tv's with three being fed by the RF2 of an old type sky box.
There are 2 amplifiers/distributos boxes in loft one with aerial cable plugged in, (but at the same time I do seem to have a direct cable run from rooftop aerial to my main tv with sky box) switching that amplifer off means I have no freeview on main tv, but there doesn't seem to be any cable from that amplifier to main tv so can only assume that somehow it is powering some sort of mask head amplifier or similiar

More recently 10 years or so ago I wanted to feed the sky signal to other rooms so have another amplifier/distribution box to do that to three tv's. This box has the rf 2 cable form sky box plugged in with output cables running to three tv's, it uses the old co-axial plugs. No input on this amplifier to plug an aerial in, so at the moment I need these two amplifiers in loft.

The problem I have got is with freeview in the other three rooms, that are fed with the RF2 signal, an intermitent problem with channels break up, and squeaky sounds for want of a better word. The SKy signal is perfect.

So I am trying to troubleshoot the problem as the freewview seems ok in main tv room. The sky signal is perfect, works well with the magic eyes in all rooms, I did change the sky box RF2 channel to channel 21 to get a good picture which works but is it possible this is somehow interfering with the RF2 freeview signal?


and connectors are these any good?



I did try another old type sky box but similar problem.

Do you think this is probably a problem with the sky RF2 distribution box ?

Many thanks for any advice.
Joe
 

Rodders53

Distinguished Member
Late last year we had an unusually prolonged period of enhanced propagation that caused interference to Freeview signal in a wide area of the UK for a few weeks. So if the problem was only happening for those few weeks and is not currently happening it may have been related to that so do nothing!

If a longer term problem and still occurring, then...

A likely issue is that ch 21 on the RF modulator. Change it to another. Anything in the 61 to 68 range is no longer used by Freeview transmitters - but mobile phones may come online in the future... But that's a different bridge to cross if/when it happens.

{Location and transmitter being used matters... postcode of a nearby (<100m) shop, pub, church will help us identify transmitter(s) and frequencies to avoid using for the $ky modulator.}

Also go over all the TV plug/socket ensuring they are made off properly and fit tight rather than loose. 99% of problems are down to dodgy connections. Particularly those connected to the $ky box and 'return/RF2 cable' back to the loft.

Pictures of amplifier boxes you have or make/model numbers from them would help.

Most Freeview TVs have a signal level and quality metering system that can be interrogated. They can give an indication of problems sometimes. A small set can be taken from a kitchen or bedroom to compare results "direct to aerial" (instead of cable into $ky box RF in) and on out from RF2 of the box. After that use it in loft to check input of the distribution amp and its outputs there.
Lots of work ant time but it may well help to resolve the problem.

Your description of how it's all fed is also unclear to me ... is it:
Aerial outside,
cable from there (direct?) to number one box in loft
cable out from that down to $ky box RF in
RF1 out to TV
RF2 out to another cable to loft
that RF2 cable to 4-way distribution amp box
--- feeding 3 other TVs?

OR????? (Include any other boxes attached to aerial cables externally, on walls or poles to the aerial)?

I'd not - at this stage - be suggesting buying a new distribution amplifier. But PROception Aerial Amplifier Distribution 4 Way would be a direct replacement using Belling Lee TV plugs. Getting the correct size screw-on F-plugs for existing coaxial cables can be a nightmare!
 

donegaljoe

Standard Member
Thanks a lot for your very helpful reply, yes its a continuous problem but still a bit intermittent, might be working ok if I called someone in to fix it, but return soon afterwards.

Yes I have tried changing the SKY RF2 channel makes no difference.

The sky signal to all rooms is good and the magic eyes work perfectly. This is the postcode BT48 0LX Derry N ireland, Sheriffs Mountain Transmitter I believe.

Would I be right in assuming that if the Sky signal is fine in all rooms then there is not probably a fault along the RF2 cable where it leaves the Sky box until it reaches the loft Sky distribution amplifier and then onwards along the cables to the three other rooms, as the same fault exists in all rooms with the freeview, except in the main living room where sky box is, though that is probably a shorter run for the aerial freeview cable, and might account for no problem there?

At the moment I don't have the model names of the amplifiers but I do know the Sky one was a Maplin job.

Aerial is on roof of house, there seems to be a direct run down the roof tiles outside of cable from aerial to the aerial in connection on sky box, however there is an amplifier box in loft (not sky one) that has a cable (runs along floor of loft) connected to the UHF in, and if I switch this amp off then there is no freeview on main TV, this is confusing to me too as it seems there may well be some amplifier (masthead?) that needs the power from this amp.

This amp would predate the time that I got the sky distribution box and would have allowed terresterial tv to be seen in other rooms.


RF1 out to TV
RF2 out to another cable to loft
that RF2 cable to 4-way distribution amp box
--- feeding 3 other TVs? Y
Yes those above are connected this way.

To be honest I am really tempted to get a proper tv aerial man in to sort it out, but what are the chances he could well replace something + his time and still not properly diagnose the problem?

Just another little matter I did get someone in last year, as in all rooms freeview was really bad, turned out the aerial cable to sky box was water logged and bare to the wire on roof, so a new replacement run sorted that out, but the cable run was done as the old one.

On a different issue I did get a new SKY dish as well, only thing I notice about it is that the info channels 998 999 I believe, really break up often, but all other channels are working fine (I just get the free channels, no sky sub) but I was reluctant to call the chap back to realign the dish as maybe it might knock a few of the Sat channels I watch off, wise thing or to do or not I wonder?

But at the moment the main thing is to get the freeview sorted out.

Many thanks once again for your kind help.,

Joe
 

Rodders53

Distinguished Member
Sherriff's Mountain (aka Londonderry by Freeview) is about 2 miles away and should not ever require an amplifier at that postcode (a local Pharmacy) even when feeding more than one set. Passive splitting should work fine {unless a professional with a quality meter has found otherwise}.
The aerial cross rods would be vertical along the long horizontal boom arm for that transmitter and point to the SouthWest.
It transmits on 29, 31 and 37 at 2 kW - Wolfbane computes 84 dBuV/m which could overload some tuners! Only around 40 TV channels.

The other source is the main Limavady transmitter 19 miles away to the NorthEast. Horizontal cross rods. It transmits on 41, 44, 47 at 20 kW and 40, 43, 46 at 10 kW (47 and 44 dBuV/m respectively). Even that should not need amplification for a single TV. It will give more TV channels than Sherriff's as it has the 3 COMmercial multiplexes in addition the the PSBs.

21 seems a good choice for the $ky modulator at your location whichever of the two transmitters you are using. Please confirm how the TV aerial is oriented. It's possible that some TV sets have found Sherriff's first on an auto tune (via signals off the back of the aerial) rather than the more reliable Limavady (if that's where it is pointing)? It would account for intermittent reception breakup problems. Manual tuning should fix that?

You say the small unit in the loft was in use before the addition of $ky. I can see how a powered splitter-amplifier located on the masthead could be wired to two points: the main TV and the loft with the loft point powering it remotely. The output from that psu for a TV is there, but unused in the loft now. There may be other cables from the masthead device also unused? (or none as it was a 2-way unit).

So we have:
Aerial with masthead RF amplifier(#1) and splitter (2-way minimum) ->
$ky box with RF amplifier(#2) split to RF1/2 out and add in of analogue $ky picture via modulator ->
Loft box RF amplifier (#3) with IR return/magic eye feature with 4 way splitter (with only three in use).

Repeated amplification can degrade signals by adding noise or - in extremes - overload tuner inputs. But it depends on the gains involved and we don't know for sure. {This is why the TV signal meters can come in useful - checking each of the transmitter frequencies in turn.}

It all depends on how much you use the RF2 $ky feed in the other rooms, and if the magic eye feature is used and useful? If it's not used the return cable input could be connected to the aerial masthead psu box output to feed that on. Or be replaced by a passive splitter IF it's a 'too much signal' breakup issue.

First check the aerial / the transmitter it points at; then the tuned frequencies then use the signal meters; finally report back with results.

Good luck.
 

donegaljoe

Standard Member
Thank you very much Rodders for your very helpful replies and time spent doing so, really appreciated.

As we speak its all working fine, oh the joys of tech stuff, but I am sure the problem will be back. As its late here going to have a good thorough read of your reply tomorrow.

Thanks again.
Joe
 

donegaljoe

Standard Member
An update on this, got a very helpful local TV guy out and he changed an item called the diplexer or something along that name on aerial, said that it was caused by the frequencies moving more towards the A group, if I took him up correctly, and the diplexer needed to be wired differently.

Seems to have totally cured the problem.

Thanks very much as well for your help Rodders.
Joe
 

Rodders53

Distinguished Member
A diplexer is for 'combining' signals from two aerials into one downlead. I guess you may be using a transmitter across the border for Saorview as well?

4th September last year was a big retune at Londonderry (Group B to A) and Limavady (group C/D to B).

Now if all your problems started on that date you should have contacted Freeview for the free assistance they were offering. It should have been in the papers and possibly mentioned on air that retunes were needed and that it might cause problems requiring new aerials in some cases?
 

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