on 06-12-2011 05:40 PM
Good Evening All
After Digital Switch Over (in this region on 17 Aug.) I set up my system to supply a Sky feed via RF2 to two other TVs in different rooms and got a good result. The details were as follows:-
1) Sky+ box SD - Amstrad approx. 2years old.
2) RF2 output reset to Channel 50 and RF power turned ON.
3) Distribution in loft (bungalow) via Globalcom F140 Professional 4 way amplifier.
4) Two accessory TVs tuned to analogue Channel 50 connected by heavy duty co-ax cable each about 15 metres from main lounge TV/Sky box.
This system worked very well until about ten days ago when the pictures on the two accessory TVs deteriorated suddenly and became very "snowy" and poor quality compared to previously. Pictures direct from the roof aerial to both these TVs are just fine.
I have checked all connections and nothing has changed as well as checking the Sky installer menu settings - still OK.
The only thing that might have changed is that we have had a "COM power-up" in this area on 23.11.11 from the Belmont transmitter (Channels 22,25,28,30,53,60) but I suppose the two things happening around the same date could be coincidence.
I then changed the RF2 output to Channel 49 and have now got an improvement,but still not as good as it was originally. The pictures are OK in "still" mode eg.when looking at a newsreader or Sky Guide/Planner lists,but suffer
from a washed-out appearance with 'ghosting' and 'image drag' when movement is going on as in a rugby match and even a golf event - the ball can have a "tail" when flying through the air (bit like a comet).
Has anybody got any ideas as to what I can do to improve things from here? Or am I trying to achieve the unachievable and will have to put up with it as it is?
Sorry this is such a long rambling story and thanks to anyone who has stayed with me to this stage!! Hope someone can help me.
Solved! Go to the solution
on 06-12-2011 10:45 PM
I think Arqiva 'A' and 'B' both powered up to the full 100Kw ( from 4Kw ) per mux, and these, I believe, are on Chs 53 and 60. I'd probably go much lower than Ch 49 on the Sky box. Remember to re-scan each tv as you change RF Channel Numbers ( also save each new channel number in the Sky menu by pressing green ).
on 07-12-2011 02:31 PM
Good Afternoon Kenneth
I have spent time this morning altering my RF output channels trying to find a better one,but with very little success. All the much lower ones in the 20's and 30's were much worse and quite snowy. Eventually I settled on Ch 45 as being very slightly better than Ch 49 but still not giving the same quality of picture as the main TV.
The worst results are seen on sports programs where there is a lot of player movement resulting in the ghosting images and image "drag" on movement. There is also a background "speckled" appearance on block colours even on relatively static programs like newscasts. I also feel that playback of recorded programs seems to be more affected than live ones,but that may just be my perception - these are mainly sports programs ,so would follow the movement criteria anyway. Have you any thoughts on that?
The instructions with my amplifier say that there should be no wallplates between the RF2 output and the extended TVs which may stop the direct current from getting through. What do you think about that suggestion?
Is there anything more I can do now?
07-12-2011 03:43 PM - edited 07-12-2011 03:47 PM
Your problem is probably to do with a strong signal now being emitted from Belmont. Presumably the terrestrial aerial is being routed through the Sky box. There may be some kind of leakage from the RF modulator in the box, so, if possible, try a different box, pre-tuned to the same RF Channel Number as on the current box. Also, try disconnecting the rooftop aerial from the Sky digibox Aerial In at the back of the box. The snowy effect may disappear. If so, the problem will be from the RF modulator in the Sky box, through your system, to the second tv.
Your chosen RF Channel number looks OK.
Strong Freeview signals sometimes need to be attenuated ( weakened ) in order to reduce or eliminate TVI ( TV Interference ). See this useful article for more.
Wallplates should be fully screened and DC-coupled ( for passing back remote IR signals to the digibox ), and any co-axial cable should be of good quality and double-screened.
Diagnosing this kind of interference can be hard, especially when a number of ancilliary devices with the potential for shielding/leakage problems are in use. You may need to consult qualified people locally, as your problem may not just be confined to your-good-self, and they may already have encountered similar customer problems with Belmont, post-switchover.
Hopefully, some other member here can suggest other things to try, otherwise have a go on AV Forums where considerably more of this kind of problem is dealt with.
on 08-12-2011 11:26 AM
Good Morning Kenneth
Thankyou for such a comprehensive and useful reply. I have certainly got plenty to go on there.
Where would I look for the fully screened and DC-coupled wallplates? I'm sure the ones that are on now don't fulfil those requirements!
Is it a quick workround to just take the coax feed out of the wallplate,fit a plug and go straight into the TV? That would then be a direct feed from the amplifier box to the TV without any joins. I can easily do that on one of the TVs,but not on the other.
If the modulator in the box appears to be the problem,is it then necessary to call in Sky?
08-12-2011 11:55 AM - edited 08-12-2011 11:58 AM
You can buy fully-screened wallplates locally, eg Maplins. Take the old one with you and consult the staff there as to what you need. Make sure everything is disconnected from the wallplate before you unscrew it, also remember where each cable behind it goes, eg SAT1 etc.
You can join satellite cables together, but you'll need 2 new F-connectors (M ) and a F-barrel ( F/F ) connector to do the job ( same idea for ordinary tv co-ax ). Speak to someone knowledgeable instore.
Getting a new wallplate may or may not solve the problem. As I said before, diagnosing these issues ( especially on a forum!! ) is often not straightforward.
Trying a different box before you buy anything is always a good idea if possible. Also, phoning a decent tv/satellite installation outfit locally may produce the answers you need, including a recommended RF Channel Number for local use. You may not be the only one with this particular problem post switchover.
If the Sky digibox ends up eventually being the culprit , a new box will be required, although if you live near Buxton in Derbyshire, Digifix ( Google it ) repair these boxes. Whether it's economic to do so is another matter.
on 09-12-2011 11:15 AM
Good Morning Kenneth
The wallplates involved here only carry the single extension co-ax cable to each extra TV - that is why I thought to just bypass one of them straight into the back of the set. The other one doesn't have enough free cable to do that,so I will go into Maplins and investigate a replacement for that one.
Unfortunately I have no chance to try another Sky box,but I do plan to do the experiment of removing the roof Aerial In this afternoon and see what happens there.
I am a bit wary of local installers. They have just seemed in the past to want to provide a new "digital" aerial -as if there was such a thing- and charge the appropriate high rate. All my Freeview programs are perfect so I don't see how I need a new aerial - it's just the distribution on Sky which is lately the problem and we use that quite a lot on a daily basis. I'll try ringing around a few more here in Lincoln and see if I can get a bit more sensible interest from someone.
If I do get a solution to this problem I will post back both to let you know how I have fared as well as maybe helping anyone else who is following this thread.
Thanks again for your help
on 11-12-2011 11:19 AM
Good Morning Kenneth
I am just posting back to report - SUCCESS !!!
Removal of the terrestrial aerial from "aerial in" on the Sky box resulted in perfect pictures on both extended TVs - in fact better pictures than we have ever had one one of them.
I called Sky to ask if this indicated a problem with the box,but was told no and that it was more likely to be an aerial/cabling problem. I thus followed some of your links more fully - eg to KLS Technical Portal and then to Garex (Spectrum Communications) where a phone call confirmed that it was probably overpowering of the Freeview signal and that this could be improved by fitting an "aerial attenuator" in-line prior to the Sky box.
I purchased one of these - at 12dB- for £5 from the local TV shop who said they were not convinced it would solve the problem,fitted it in-line and Bingo!! the pictures were perfect again. I also have the full range of Freeview programs on all TVs.
So,the answer is -fit an aerial attenuator when the transmitter signal is powered up and causes problems.
Hope this might help others faced with the same difficulties. The attenuators are also avaiilable from Maplins online or from store.
Once again,Kenneth,huge thanks for your interest and help in this. I don't think I could have solved it without your assistance. The local professionals weren't much use - in fact, the aerial installer and the TV shop still didn't accept that it was the Belmont power-up that was causing the problem!! Doh!- my brain hurts!! The solution has proved them wrong.
on 25-10-2012 04:11 PM
on 23-11-2012 10:38 AM
I have just purchased an attenuator in the hope it will fix the signal. Did you just put the attenuator directly into the sky box where the RF aerial cable goes and then put the aerial directly into the attenuator?
on 06-02-2013 03:56 PM
Hi guys/gals.... Glad i came accross this post.. here is my set up and problem
the set up is here in clifden, galway, ireland - The new Digital Saorview channels comin on channel 26
Equipment, but we are not using Saorview so there is no Rf aerial going into the sky boxes. we are only using Sky.
1 x Sky HD record-able box ( Has RF2 out)
1 x Sky HD Multi room NON record-able box ( Doesn't have RF2 Out )
1 x Trilink RF Modulator ( To get RF 2 off the 2nd sky box above)
1 x SPCF4 Combiner
1 x 4 Way Woolsey RF Amplifier
3 x TVs
3 x Sky EYES..
The Set up
RF 2 out of the first sky box ( on RF channel 68 ) into port "0" on the SPCF4
Scart out of the 2nd sky box into the Trilink RF modulator and RF2 out of the Trilink( Channel 36 ) into PORT "1" of the SPCF4
Coax out ( all coaxs are crimped with compression F Type plugs) of the SPCF4 in to the UHF on the 4 way woolsey. Then out of the Woolsey to the 3 TVs...
and im getting a ghosting image on the screens... can anyone help or have seen this before..?
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on 06-02-2013 03:58 PM
sorry.. forgot to ask... there is a gain switch on the Trilink modulator which i will turn down... but if i was inserting an attenuator, where would i put it in the mix? ( the coax out of the SPCF4 and going into the Woolsey amp...?)
22-03-2013 10:03 AM - edited 22-03-2013 10:14 AM
The attenuator mentioned in this thread is only used the reduce the incoming UHF signals.
While you may need to reduce the level coming out of the 3rd party modulator, an easier way to see if they are interfering with each other is to unplug the connection going into port 1 on the SPC4F.
Incidentally, have you turned on the RF2 power supply and the SPC4F has a lit red LED?