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Old 17-04-2009, 13:03
chris higgin
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I have just replaced a single L.N.B with a quad L.N.B on my Freesat dish, the old L.N.B was circular the new one is oval,
this was to take advantage of the twin inputs on a new Humax P.V.R

Does it matter which way the L.N.B faces the dish, ie at the moment the oval is upright. The picture quality is as good as before as well as signal strengh, any advice would be appreciated.

Thanks Chris
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Old 17-04-2009, 13:15
froxfieldrover
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I have just replaced a single L.N.B with a quad L.N.B on my Freesat dish, the old L.N.B was circular the new one is oval,
this was to take advantage of the twin inputs on a new Humax P.V.R

Does it matter which way the L.N.B faces the dish, ie at the moment the oval is upright. The picture quality is as good as before as well as signal strengh, any advice would be appreciated.

Thanks Chris
Well when I swapped my single lnb for a quad lnb I got no picture at all and the signal strength was virtually zero. I was really upset until after about 2 hours I realised that the way the old lnb slotted in was entirely the opposite direction to that of the new. I turned it round and then got a 95% signal strength and brilliant image. My thought would be if it's working then it's the right way round and you must have it right anyway! Although it does seem odd to me, my oblong lnb hangs downwards from the sat arm - as I say that is the opposite to before.
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Old 17-04-2009, 16:03
chris higgin
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Sorry perhaps I did not explain myself properly, the L.N.B is facing the centre of the dish as before, I was wondering whether the oval l.n.b should be vertical as it was supplied or horizontal.

chris higgin
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Old 17-04-2009, 16:09
BBMF
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The picture quality is as good as before as well as signal strengh, any advice would be appreciated.
if it aint broke......
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Old 17-04-2009, 17:08
mk-donald
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For Astra satellites as I understand it for southern England the LNB is usually specified as being skewed at -13.2 degrees (eg see the www.dishpointer.com site "LNB Skew" ).

ie When looking from the back of the dish rotate -13.2 degrees from its default straight down position.

Mirror image: when looking from the front/dish side: the lnb should be slightly clockwise, ie if it was the HOUR arm on your watch, it should be angled at 6:30 position rather than position straight down at 6:00 - which could/should give you a better Strength/Quality.

From my little informed position as I understand it the signals from the satellite are sent in both HORIZONTAL and VERTICAL polarised - ie your dish is receiving overall signals in a "+" pattern, but because the satellite isn't 100% square on to the dish, that cross tends to twist round a bit towards "x" and hence rather than perfectly vertical "+" the LNB twisted round those 13 degrees towards "x" means it better in-line with those offset/twisted horizontal/verticals.

MKD
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Old 18-04-2009, 08:52
chris higgin
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Thanks for the replies I think I will leave well alone.


Chris
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Old 22-04-2009, 09:58
edbanga
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I have just replaced a single L.N.B with a quad L.N.B on my Freesat dish, the old L.N.B was circular the new one is oval, . . .

Thanks Chris
I may be wrong but I think the reason you new LNB is oval is because it's specifically designed for a Sky dish, which is elliptical with its major axis in the horizontal. Conventional dishes are also elliptical but have their major axis in the vertical. The fact that you are getting an acceptable signal strength is most likely because you either have a Sky dish or one that’s somewhat larger than the 60mm Sky dish. Skew angles as previously mentioned still apply, but as they say if it ain’t broke . . .
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