? about polarisation.

nick6470

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#1
Hi all

Here is my problem:

From astra 19 (astra 28 is prime focus) i can receive all the channels with a horizontal polarisation but i cant get the ones on the vertical pol. to remain stable ,i have a signal strength of about 65%, but the signal quality jumps around between 10% and 45% so the picture is therefore never stable. I have tried adjusting the skew and this seems to make a slight difference but not really significant, are there any other things that i can do to improve the quality of the signal (excluding increase in dish size), would maybe a new lnb help? mine is a cheap no name jobbie, should i splash out on this invacom 0.3db lnb?

Any help greatly appreciated.
 

rolfw

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#2
May be that you are not hitting the dish centrally with your offset LNB, try sliding it in slightly and tweaking to see if you get an improvement, if that doesn't work, try moving it away.
 

nick6470

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#3
Does my offset lnb have to point at centre of dish or just parallel to my main focus lnb? So what i mean is do both lnb's have to point at centre of dish?
 

rolfw

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#4
If you are using an offset bracket, rather than a preset monobloc LNB, then the primary focus sed LNb will automatically be pointing at the centre, the offset however, can be pointed well off centre and still produce passable results. To produce optimum results, it really does need to be pointing exactly at the centre and also be at the correct focal length, it is not unknown for bracket bending to be effective.
 

nick6470

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#5
Thanks Rolf, i have a preset monoblock so i guess i really need a offset bracket to get better results. Thanks again.
 

rolfw

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#6
Sorry mate, just had a thought, what type of monoblock is it? didn't think that they made a 9 degree one.
 

rolfw

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Berkshire
#8
OK Nick, that's a twin mount, it takes two lnbs, a monoblock is actually two lnbs combined in one case.

Having said that, it would appear that this twin mount is for hotbird and Astra, so this will mean that you are looking past the centre of the dish for the second satellite.
 

nick6470

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#9
Thanks for your help on this, do you have any suggestions as to how i can improve my setup? My offset lnb is not pointing at the centre of the dish and with the mounting i am using it is not possible to get it pointing at the centre.
 

Channel Hopper

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#11
Nick

If you are in the UK, the dish should be pointing squarley at the lower power satellite, in this case 19 East

You will have to reverse the feed assembly on the dish and twist the whole system round on the pole by 9 degrees
 

rolfw

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#12
Nick is in Germany CH, hence the 28.2 focus. But will never get good 9 degree secondary sat results, using a 6 degree bracket.
 

nick6470

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#13
Thanks for the suggestions but i still have not being able to resolve the situation and my sat installer has gone (AWOL )(-red ), what i fail to understand is that even with my apparent incorrect setup i can still receive most of the channels from Astra 19, but i cant get Sat1,Pro7 and Kabel1 which all have the same frequency and polarisation.. strange but i guess there is a good explanation.

I guess i need to look for a bracket that is fixed at 9deg and that points the lnb at the centre of the dish, would that be correct?
 

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#14
A problem with one frequency suggests a difficulty with the cable run rather than LNB anomaly

If you really need the channels mentioned you could always invest in an analogue receiver to ride shotgun.
 

rolfw

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Berkshire
#15
Can you get
BBC World
Fashion TV
QVC Germany
Viva Plus
CNBC Europe
N-TV
Viva
EuroNews

These are all vertical Channels.

I've found that the vertical channels seem to suffer more with a horizontally off centre focus.
 

nick6470

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#16
Hi Rolf

In can get QVC Germany,Viva Plus,Viva,N-tv,Euronews

Cant get Sky news, sat 1,pro 7,kabel 1, or dsf all these channels except sky news have the same frequency 12,480GHz and V polarisation and typically these are the channels that i really want!!

Any help as always appreciated.
 

rolfw

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My Satellite Setup
Technomate 5402 HD M2 Ci, DM7000s, Transparent 80cm Dish, Moteck SG2100 DiseqC motor, lots of legacy gear. Meters: Satlook Digital NIT, Promax HD Ranger+ spectrum analyser.
My Location
Berkshire
#17
Do you have a digital phone Nick? If you do, try turning it off and see if you get the same problems.
 
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#19
nick6470 said:
I do have a digital phone, so i will give that a go tomorrow.

Thanks
Have you found a resolution to this issue as I have the exact same issue. Everything found on 19 except DSF, ProSieben, Kabel 1, Sat 1 (12.480 V). The receiver is saying that I have a signal strength of 80% and 90% signal quality.

Darren
 

nick6470

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#20
So i tried turning off the phone but this didnt seem to help the situation, do people think it would make a huge difference if i tried one of these invacom lnb's?

Whats your setup darren? Dish size etc
 
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