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Evening picture break-up


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Only happens here when there is heavy rain falling between our dish and the sat'. Some channels are weaker than others and in our case True Movies 2 is the first to go. At the moment our Sky box shows, using the Services, System setup and Signal test buttons, Signal Strength up to the K in O.K., quality just to the right of the 2 in network ID 0002 . Lower than this might suggest dish is not well aligned. It is raining here just now but not heavy...................................................JR
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Better you arrange to see the TV as you play with the dish if possible. There is sometimes a slight time lag between moving the dish and the response on the screen. I have done it with two people where this was not possible. Make very small movements and marking the start position with a felt tip pen can be helpful if you loose the signal altogether. Depending what sort of dish you have you may be able to rotate the LNB as its position can be almost as important as the dish alignment. Don't think this is possible on a Sky minidish. I would adjust the dish position to get maximum signal quality and strength and then adjust the LNB if possible. It would be better not to have any trees or vegetation close to and in front of the dish and between it and the sat'.............................................JR
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You can get a cheap sat signal strength meter from ebay which makes getting the dish position right a lot easier if you can't see the screen. Not fantastically accurate but I found it helped al lot. I agree with JohnRoss, rotating the LNB makes all the difference. but relying on someone else watching and shouting up the delayed result of your tiniest change is very difficult, particularly as even the smallest flex in the dish makes quite a difference.
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[quote user="plod"]May seem obvious but does somebody watch the tv and somebody twiddle the dish?[/quote]

I take an extension lead, the digibox, a portable TV, and a short length of co axial cable outside. So far I have been lucky and have always been able to mount the Dish about 8 feet off the ground. It is a bit harder if it is 15 metres in the air. You then need a trusted person to watch the TV and shout BETTER or WORSE like a demented Golden Shot candidate.

At a guess the symptons may be an LNB towards the end of its life. Try aiming a garden hose and cooling it down. If that clears the problem a new LNB rather than alignment may be the answer.

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We brought a mini-dish with us but most folk around here seem to have the circular 80cm dish. We did have the LNB suffer from overheating and the polarization switch packed up and we had to switch it on the remote until a replacement arrived. I think the dish should be matt black as light colours must reflect and focus heat onto the LNB at some point as the sun tracks across the sky..........................JR
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That's an interesting point JohnRoss,

I am intending to lightly spray my dish to camouflage it against the stone wall. I take on board your thought but the LNB is black and will absorb far more heat than would be reflected by the dish. Maybe painting the LNB white will keep it cooler?

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Ok well when we got here I stupidly sprayed the dish a light yellow to match the crepi on the house wall and a few months later the LNB went wrong as described, coincidence? I think not. Don't know about the colour of the LNB, the circular ones seem to have a white front but I don't think I would risk painting them as the RF properties at Gigahertz of the paint may be unknown. If I remember rightly our minidish and LNB were dark green when new................................................JR

PS A lot of the techie forums say you should not paint the dish with metalic paints and never with gloss (reflective) paints and never paint the end of the LNB facing the dish.

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Never paint the LNB - You can buy transparent plastic dishes which disappear pretty well - Form practical experience we acheived a perfectly satisfactory signal quality of 70 to 80 % with a Sky minidish a bit further south than your instalation. Using the same digibox and  100 kilometres further South I reached between 95 and 100 % with an 80 cm dish.
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I am not silly enough (yet at least) to paint the working end of the LNB but the remainder of the cover......I wonder? Got a couple of LNB's so may experiment with one.

I get roughly an 80% signal using 60cm mini dish but it may also have something to do with neighbours honey suckle which is growing to riduculous height now. On the one I installed for the family I did get an almost perfect 100% signal and quality, just dropped back as I did the final tighten of the bolts.

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