Can anyone decipher what is going on?

[Daft Doctor]

We are having huge problems with the installation of the satellite TV system at our new house, hopefully in time the technicians will get it right, but at the moment we not only have only one satellite feed working. We have a sky box with a card to receive free to air channels only, but the pattern of channels receivable/not receivable at the moment has got me truly baffled. We are in the alps and have upgraded to an 85cm dish, even though our 60cm dish was coping ok after the recent tightening of the UK beam except in bad weather. The single feed signal strength is 80% and quality is 90%. I wonder if anyone with technical knowledge (including but not exclusively Martin and Jako) can shed some light on why the following pattern is the way it is?

A sample what we CAN receive is as follows (in order of apprearance on the Sky TV guide): ITV1, 2, 3 & 4, Channel 4+1, E4, E4+1, More4, 4seven, BBC1HD, BBC2HD, ITVHD, ITV3+1, True Drama, True Ent, Propeller, Channel 4HD, some regional BBC1 channels.

A sample of what we CAN'T receive is as follows: BBC2, Channel 4, Channel 5, BBC3, BBC4, ITV+1, More4+1, Channel 5HD, Channel 5+24, Channel 5+1, ITV2+1, ITV4 Plus, ITV4+1, ITV2HD, ITV3HD, BBC3HD, BBC4HD, ITV4HD, More4HD, some regional BBC1 channels.

Could it be something to do with polarity or the frequency range of the LNB or something completely unrelated? If anyone can help solve the puzzle I'd be truly grateful.

[Pierre ZFP]

A quick look at Lyngsat shows you seem to be getting all the Vertical polarised channels but not the Horizontal ones.

This could be because your Sat box is set to only scan for vertical polarity or maybe the LNB isn't correctly orientated in the holder. For instance, my LNB needs to be rotated 45 degrees with an impossibly small arrow pointing 'up'

[Jako]

Yes Daft Doctor appears to receive the vertical polarised channels only. This could be due to a wrong LNB skew (rotation of the lnb around its own axis) or a malfunction of either the  LNB or the receiver . However, as a vertical polarisation requires a higher voltage (18v) than a horizontal polarisation (13v) , a malfunction is less likely.

[Daft Doctor]

As you've both already been helpful and knowledgable, I'll expand a bit on the global problem we're having to see if you can give me some ideas to feed the technician when he next comes back.

The new house has a communications box in the sous sol. 4 input cables come into that from the 85cm dish and quattro LNB, along with a cable from a UHF ariel. These all input into a Sedea Mini Switch 659805 with 5 entry ports and 8 exit ports, 6 of which are used to carry signals (supposedly from all sat & UHF inputs) to each of the 6 TV/Sat/Radio sockets around the house. The idea is that for Sky+ HD for instance, with the miniswitch working, each of the 2 tuners on the sky box is connected to a separate satellite socket in the lounge and each should be able to receive an independant and comprehensive satellite signal enabling normal (happy) viewing/recording/playback.

Problem is that it doesn't seem to work. Our trusty Sky HD box didn't work when we moved in, refused to even initialise and couldn't receive a signal in either tuner. Innocently I thought the box had gone kaput during the short journey across town, but I've tried 2 Humax boxes and another Sky box (which was borrowed from a friend of mine and works perfectly chez-lui) with the same result.

The technicians came out after my initial attempt with our sky box and claimed that signals were indeed available at all the sockets and the problem must be with the decoder. As this clearly wasn't the case, at the weekend, having deduced which of the outputs from the miniswitch served which sockets, I tried bypassing the miniswitch altogether, testing the 4 LNB outputs individually. Despite doing this I was only able to get any signal at all from one LNB output cable, so only from one lounge socket, but even then, within minutes the one 'live' output changed to being from a different one of the 4 LNB outputs before disappearing altogether soon afterwards.

The technician was here this morning, was up on the roof checking the connections, then pronounced that he thought the miniswitch was faulty, but had managed to get what sounds like vertical polarity only channels to one output from the miniswitch. He is coming back when the replacement switch has arrived.

I'm not saying he doesn't know what he is talking about, but it's true that the very experienced guy who installed the equipment only 4 weeks ago has retired and passed on his customers and mobile to a 3rd party. I'd be interested in anyone's thoughts on diagnosis/corrective measures here. I should say that the miniswitch is the type which is powered up by the decoder when that is switched on, and in all cases this powering up of the switch seems to work normally (green light illuminated on the switch). Finally, I will also say that when I had a live feed on Saturday, I switched it to all 3 lounge sat sockets sequentially and they all worked normally.

Sorry for the essay and the imposition, hope you all haven't fallen asleep whilst reading!

[Daft Doctor]

Now I'm reading more about Quattro vs Quad LNBs I'm starting to understand why my attempts at direct connections didn't work, I didn't realise that with a quattro the 4 outputs aren't universal but each carries specific polarity and voltage ranges. It is only the miniswitch which can unite everything then pump it out to the sockets, is that right? If so it probably is the miniswitch which is faulty!

[AnOther]

You're right about how the quattro works but why on earth did you go for such a system ?

As you are discovering quads and quattros are completely different devices with quattros intended for medium or large scale distribution systems not domestic situations.

FYI the 4 outputs from a quattro are:

Low band Horizontal

Low band Vertical

Hi band Horizontal

Hi band Vertical

The receivers you hang onto the multiswitch select which of those they want according to the channel you set them to, or in other words the multiswitch looks to the receiver like an LNB.

[Daft Doctor]

Hi, fact is we have a new house of 180sqm and the constructor advised that for future proofing it was the best way to go. Lets hope it will work well once the miniswitch is replaced

[richard51]

Zzzzz, from your previous post . You are obviously very aware and knowledgeable about the system installed. However, as you are probably already acutely aware, whenever there are multiple people involved things take a little while to get right.

[richard51]

NB: I've been, in the past, convince that a problem can be rectified by doing X, Y or Z by talking to experts, but in the end the problem has been solved by something totally unexpected.