skyQ lnb no signal on one output

fancyabrew

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grrrrrrrr. I was meant to be having Q installed today but is all gone horribly wrong! Before I explain, I can't fault the Sky installer AT ALL he was really good and spent about 3 hours trying to get it to work!
Anyway the problem seems to be with the 2nd LNB on the new Wideband LNB feed that SkyQ uses, the 1st works totally fine, the second gets NO signal, only power. Just to add I've got SkyHD and that works totally fine and with a decent signal (old non wideband LNB obviously). First thought was the cable (my cables goes to a distribution box just to confuse things). But we tested the cable BEFORE the distribution box to rule that out and it fails! Laid new cable, fails, various LNB's fails. BUT running the installers tester directly attached to the LNB WORKS! Attach a 2m length of cable to the LNB and test from that FAILS!
So rebooked with a team leader SkyQ expert next Sunday. Installer never seen anything like this before. And I must admit being in IT myself and knowing a little bit signals going down cables it is all VERY weird!
Anyone who knows anything about Satellite have any ideas!? The village has a TV relay + mobile dishes on the mast very close to the LOS, could it be some interference only effecting wideband (as normal Sky works fine) from this? If so we're probably snookered! Not sure if its the Horizontal or Vertical polarisation that's got the issue, not really sure if Sky splits the polarisation ie LNB output 1 is one polarisation and the 2nd the other.
 

smoggy07

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I know you say he tried new cable and LNB(s) but....... Did he try a new receiver or power supply?
 

fancyabrew

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he tried a new LNB and a new run of cable. If he connected his tester to the LNF directly it worked if he connected it to the end of the run of cable one feed work the other failed, no signal! Really, really odd!
 

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It almost sounds like the LNB was sending/receiving a very weak signal that gets attenuated too much by a run of cable. Very odd though as even a 2m short bit of cable shouldn't make that much difference!
 

rolfw

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Unfortunately there's not enough practical information available about the Sky wholeband LNB at present, as it's only the Sky installers who have access to them.
 
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fancyabrew

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I thought the same sounds like attenuation. It really is very weird going to have to wait till Sunday and hope we can get it sorted by moving the dish
 

PaulR

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Please let us know what the problem was when/if it gets sorted.

As Rolf says, there's little known about these wideband LNBs yet but my gut feeling is that it's faulty LNB or batch of LNBs.
 

fancyabrew

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"hopefully" I'll get it sorted on Sunday!
 
A

Archive4

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It almost sounds like the LNB was sending/receiving a very weak signal that gets attenuated too much by a run of cable. Very odd though as even a 2m short bit of cable shouldn't make that much difference!
Not too unusual, I´ve had the same thing in Spain with " cheap " cable causing massive attenuation, extend the cable and the signal improves. Must be caused by unbalanced signal reflection cancelling out the intended signal by being 180 degree out of phase. Correction with balancing or attenuators should improve this.
That said, one working , one not is very strange, but never having met this " beast " in the flesh, it is very difficult to work out the problem. If only we had one to dissect!
 

timo_w2s

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Not too unusual, I´ve had the same thing in Spain with " cheap " cable causing massive attenuation, extend the cable and the signal improves. Must be caused by unbalanced signal reflection cancelling out the intended signal by being 180 degree out of phase. Correction with balancing or attenuators should improve this.
That said, one working , one not is very strange, but never having met this " beast " in the flesh, it is very difficult to work out the problem. If only we had one to dissect!
Yes, RF is a black art but I would assume the Sky installer was using cable that would be approved for SkyQ use, but then they do say you should never assume....
 

Topper

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Perhaps a god can " edit " the words!


Gods control many things our amorphous tentacles reach far and wide but we certainly have no power to edit a Youtube video:eek:
 
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I apologise unreservedly for my lack on knowledge in relation to the " forum Gods "
There was stupid little me thinking the " Gods " were all powerful and totally omnipotent in relation to us mere mortals, guess it´s " Q´s " day off!
 

Channel Hopper

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Unfortunately there's not enough practical information available about the Sky wholeband LNB at present, as it's only the Sky installers who have access to them.

There is however a plethora of older information on the site on dual tuner failures out of the box and/or within warranty period on older Sky systems, plus chronic power supply 'anomalies'.
 

rolfw

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There is however a plethora of older information on the site on dual tuner failures out of the box and/or within warranty period on older Sky systems, plus chronic power supply 'anomalies'.
Not much of that is relevant, as the same problem was experienced with the installer's meter, so unlikely to be the Sky Q box and there is little or no information on the performance of the Sky wholeband LNBs.
 

fancyabrew

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yep its NOT the SkyQ box as the installers test kit also failed (works at the dish not when attached to a length of cable!)

GRRRRRRRRRRRRRR
 

PaulR

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What meter is now used by $ly for the wholeband LNBs? Does anyone have an idea?
 

Channel Hopper

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Not much of that is relevant, as the same problem was experienced with the installer's meter, so unlikely to be the Sky Q box and there is little or no information on the performance of the Sky wholeband LNBs.

Not quite, a Q LNB is (from my limited knowledge) a two port LNB combining both low and high frequencies from one polarity into a seamless range by shifting the upper local oscillator down to 10.4GHz . The second port does the same with the opposite polarity.


BUT running the installers tester directly attached to the LNB WORKS! Attach a 2m length of cable to the LNB and test from that FAILS!


There is a greater chance that the installer did not select the correct transponder group on the meter when checking the second port, as opposed to the LNB itself being low output on one , or both polarities.

Additionally a distribution box is mentioned within the mix of new and legacy equipment conected on site. Quite how a dual band LNB can be used on a four port distribution box without a Q type expander to convert back to the four port requirement is anybody's guess based on the o/p's initial post. Was one installed before changing out the LNB on the roof ?
 
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Thanks CH for your " limited knowledge " which is vastly superior to my non existent knowledge.
From what I can assimilate from your post, it acts a bit like a quattro lnb with a wizzy bit that puts both high and low on one port, thus only requiring two ports instead of four to cover the entire spectrum?

The thing I want to know, did the sky installer attach his test " box " direct to the lnb, or via a test cable? If via a test cable, what is the difference between the test cable and the 2m cable that did not work?
 

PaulR

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I don't think there's anything wizzy that adds the low and high bands together. It's more a case of the oscillator mixing with the incoming frequencies and moving the whole lot down in one continuous block. The lowest frequencies are in what is currently terrestrial TV area and the highest frequencies are well above the high frequency of a standard LNB.

With regards to anything else I'm learning as I go along following this thread.
 
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