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Do I have a faulty aerial or is it a booster?

Discussion in 'Audio Visual' started by JOEPUBLI, 2 Mar 2013.

  1. JOEPUBLI

    JOEPUBLI

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    I moved into a house which has a no of TV points - in bedrooms, kitchen etc. The SKY feed comes into the lounge and the dining room - each has two sky cables for the sky box. The previous owners had a sky box in both. I just have sky box in the lounge.

    When I bought the house I was told that on TV CH 6 I could receive SKY in the bedrooms. I have never managed to get that to work. I cant work out how the sky would get distributed round the house.

    Secondly, The bedroom and the kitchen TVs worked fine as did the lounge TV (both on aerial and on SKY box). However recently the TVs connected to the aerial socket don't work - sometimes there is a very pixilated picture with intermittent sound on BBC1 and BBC2. I first thought it was the TV on the blink but that's not the case.

    Near the loft, there is a "Clapham Junction" of wires connecting to three boxes which I guess distributes the aerial signal to the various aerial sockets round the house?

    . I attach a picture. I'd be grateful for any explanation of the set up:

    For example:
    1. is the top cable the aerial signal coming in?
    2. This cable then goes into the top white box which is powered - the socket marked TV has a splitter attached with a cable going into the middle black box and the other going off somewhere - what's the function of these boxes?
    3. There are a no of cables coming out of the black box going into the bottom box - again, what does this box do?

    How do I work out whether my aerial needs replacing or whether its one of the boxes by the loft? and secondly, how do I get sky in the other rooms?

    Any help/explanation appreciated as I'd like to understand the set up and hopefully get it working.

    If I get someone in to look at it, what should I expect to pay?

    Thanks Again[wiki][/wiki]
     
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  3. OwainDIYer

    OwainDIYer

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    The UHF output from the Sky box must get sent from the Sky box back up to the distribution somehow, possibly through the white Y-thing on the top Labgear box. This may be through a socket marked 'return' in the lounge. It might not be on TV CH6 unless your Sky box and TV is tuned the same way as the previous occupants' which is unlikely.

    However whoever installed that lash-up has used TV aerial cable, not satellite, as far as I can see, which a combination of amplification and attenuation, poor cable layout and tightly bent cables, unnecessary coupler etc.

    Try asking on news:uk.tech.digital-tv
    http://groups.google.com/group/uk.tech.digital-tv/topics?lnk
    and hopefully Bill Wright will reply
     
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  4. JOEPUBLI

    JOEPUBLI

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    Thanks OwainDIYer. Just about everything is that way in this house!
    Thanks to the clues, I now know that the top box is an amplifier. Don't know what the other two boxes are but one of them must be a distributor - it must be the black box in the middle as it has a no of connections coming out of it. What then is the bottom box made by Taldis - it would seem to be a distributor but it has only two cables going into it apart from power.

    I have taken pictures of the sockets in the two lounge rooms downstairs. As you say, the UHF signal from the skybox must get fed back to distribution box somehow - well one room has just ONE aerial type socket (plus 2 sky cables).
    The other room has two panels with two sockets each - None of them have any markings on them.
    Any further pointers appreciated.

    Thanks for the suggestion for the other forum. I will wait to see if anyone here can help first.
     
  5. ChrisFrost

    ChrisFrost

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    I can tell you what most of this gear is, and how it would normally be used. Your Heath Robinson lash-up might not follow the rules though, so be prepared to do a little cable detective work rather than taking the following as gospel for your installation. Here we go....

    The top white Labgear box is a power supply. I would expect to see one of these where there is a masthead aerial amplifier (i.e. a booster box attached to the aerial mast). The IN would be the feed from the aerial via the masthead amp. The same cable carries power back up to the masthead amp. This is called phantom powering.

    The OUT from the Labgear box looks like it goes to a two-way splitter My best guess is that one of those outputs feeds a nearby socket. The other looks like it goes to the left-most input on the black box.

    The black box closely resembles an Antiference masthead amp. The things that look like spark plug covers on the cables haven't been used on your install, hence the minor difference in the images. The power for this is usually phantom supplied up one of the output leads. This would explain the presence of the "Taldis" box. It is the phantom power supply for the Antiference amp/splitter.


    Your Sky box RF2 feed has been introduced some way in to that system. Generally we would take the aerial feed (with any amplification if necessary) and feed that in to the Sky RF input. Then take RF2 out and put that in to a powered splitter. If you would like to control the Sky box using Sky IR eyes then the splitter must have "DC Pass".
     
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  6. JOEPUBLI

    JOEPUBLI

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    Thanks ChrisFrost. The answers here have solved the not getting SKY round the house issue. It needed connecting up the skybox in the other room and setting RF2 on skybox to On.

    I still have the issue of not getting clear picture or sound on the aerial channels - the picture is very pixilated and the sound is disturbed/skippy. Someime BBC1 works OK for a while on upstairs TV. On downstairs TV I get no channels - it says no signal.

    So it seems I am getting some signal upstairs and nothing downstairs from the aerial. This was working fine until a few weeks ago when suddenly started getting this.

    On the upstairs TV I can look at "signal information" channel by channel.
    For BBC 1: it says channel 23 , Network London, Modulation 64QAM,quality 30, Strength 91.
    on ITV3 where the picture and sound is very poor, it says:
    channel 25 , Network London, Modulation 64QAM,quality 18, Strength 91.

    So it seems the problem is with the "quality" of the signal - what is causing this. The quality figures also seems to fluctuate.


    Any thoughts welcome.
     
  7. OwainDIYer

    OwainDIYer

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    what sort of aerial do you have?

    And if you are willing to post your postcode someone can check which sort of aerial you ought to have. It may just be that terrestrial reception at your location is rubbish.
     
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  8. JOEPUBLI

    JOEPUBLI

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    OwainDYer - thanks. Haven't got a clue of what type of aerial I have but here's a picture.

    My postcode is wd18 7lb.

    But the thing is that the aerial and the TV was working fine late last year. I was away for a few weeks. So something has happened in between. We did get a new skybox but that shouldn't have affected the aerial signal.
     
  9. ChrisFrost

    ChrisFrost

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    Your diagnosis is correct. Quality is far more important than strength. You can have a rubbish quality signal due to the wrong aerial type or poor alignment or a bunch of other issues and then boost the hell out of it so you then end up with a high power rubbish signal. It does nothing for the quality.

    The thing with digital TV signals is the digital cliff. Analogue would get fuzzier as things go out of whack. You could see a progression as things got worse. Digital keeps working right up to the point where it's just not good enough, and then it really loses it.

    Start with some basic troubleshooting. Go out and have a look at the aerial. Is it still attached and pointing in the correct direction. Do all the cables look like they're still connected too? Then try connecting a TV to a point as direct to the aerial feed as possible. If you have the masthead amp as we suspect you might then you'll need to be on the TV side of the power supply. If you have good results then you know the problem is somewhere in the distribution chain.
     
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  11. JOEPUBLI

    JOEPUBLI

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    Thanks Chris

    I have had a good look at the Heath Robinson setup. Your analysis of the gear is spot on. The black box says "Antiference UF3730 UHF Combiner 21-37/39-69. The connections are as you described.

    Three cables are going downstairs - one from the splitter connected to Labgear marked TV. One from the right connector on the Antiference and one from the Output connector on the Taldis.

    The Top outlet from Labgear is marked TV and the bottom - Aerial. The cable coming from the roof is connected to the Aerial.

    The cables look OK and they were working before. I cant get onto the roof to look at the aerial.

    I think what you are saying is that I should connect up a TV to the TOP Labgear output marked "TV" and see whether I can tune in good signals? IS this correct?

    IF so, it has a screw in type connector(type F?) rather than a push in type that is in an aerial cable - how do I connect an aerial cable to it? Is there an adapter that can be bought? Apologies for the newbie questions but am keen to find it out for myself.
     
  12. ChrisFrost

    ChrisFrost

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    Yep, that is correct.

    What you'll need is a length of aerial/satellite coax cable fitted with a standard TV-type aerial plug on one end and an F connector on the other. Add an F-type to male RF coax plug like this and you'll have most angles covered.

    F connectors are becoming "standard fit" on a lot of RF distribution gear now, so learning how to fit one to a bit of cable will be useful knowledge. They're easy to do and there's plenty of How to videos on YouTube. If you can wire up a 3-pin mains plug then an F connector should pose no problem. While you are on YouTube have a look at how to fit a TV coax plug as well.





    [Note for anyone super pedantic: I haven't referred to Belling-Lee plugs simply because most noobs wouldn't have a clue that it's the correct name for what they'd know as a TV aerial plug.]
     
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  13. Sam Gangee

    Sam Gangee

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  14. JOEPUBLI

    JOEPUBLI

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    Thanks Chris.
    Connecting a TV direct to the Top Labgear output marked TV works perfectly. Looking closely, the splitter connection was actually a Belling, otherwise known as an IEC ;)

    So this means that aerial is OK. I tried with two different TVs and the signal quality improved to 91 and I could get all channels without any pixiltion or sound distortion.

    So what next? Do I now move to the black box in the middle?
     
  15. Sam Gangee

    Sam Gangee

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    I don't see the point of the "Antiference UF3730 UHF Combiner 21-37/39-69" unless it's being used as a bandpass filter. You have a UHF TV aerial and a VHF radio aerial and this "diplexer" won't handle radio. So you can safely eliminate it and connect the UHF aerial direct.
     
  16. Sam Gangee

    Sam Gangee

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    The usual cause of sudden failure is the power supply or the amplifier that it's powering. PSUs fail through overheating and/or capacitor failure. Amplifiers fail through water ingress (outside). My money is on the PSU so measure its output voltage with a multimeter.
     
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  17. JOEPUBLI

    JOEPUBLI

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    Sam - please could you explain that in terms of the cables. I think you are saying that I should take the second cable fro the top splitter and rater than it being plugged into the leftmost terminal on the black box it should be connected to something else?

    I thought may be this black box splits the signal for different outlets?

    I should also say, that downstairs there are two boxes that distribute radio and music round the house. I don't know whether that all wire up separately or could be part of this set up. There are separate wall panels for the music and speakers in the rooms.
     
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