LNB Skew

dave branson

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I have just done a calculation, using the Satlex site,which indicates a skew angle of -16.93,does this mean that the LNB should be at about 11-o,clock
looking at the dish,at the moment i am at about 16-o,clock with my LNB.
Is it possible that i am the wrong way round.(if that makes sense)
 

Burnham Beech

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11-o,clock should do it.

Don't understand 16-o,clock, was that a mis-type?

This answer was wrong - sorry. I suggest you get SMWlink - this gives you a little picture of LNB skew so you don't have to worry about what the + or - means.
 

dave branson

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Burnham Beech said:
11-o,clock should do it.

Don't understand 16-o,clock, was that a mis-type?

I meant 4-00,O-clock,whilst i am getting 2D reception at this position,it would seem that I have the Skew of the LNB completely the wrong way,if i
use the calculation,ie Lat/Long.for Florence on the www.satlex.de site.
 

devonbrown

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Is the angle given at this site (mine is -35.86) as viewed from the dish or towards the dish?
 

rolfw

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I would say that for Florence it would be about quarter to seven as you look at the dish from behind the LNB. :) 18:45 for the new age thinkers :D
 

Zorba

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rolfw said:
I would say that for Florence it would be about quarter to seven as you look at the dish from behind the LNB. :) 18:45 for the new age thinkers :D

In Limassol its about five to eleven.Is that because we are 2 hours ahead of GMT? :confused :D :D
 

dave branson

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i tried the SMW link,that gives -17.5,the following is my exact lat/long
Lat 43.617,long 11.467.
Will someone please do a check calculation for me?thanks.
 
H

Happy-Buddah

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Hi dave branson

You are correct, this is only true for fixed dishes, as a motorised system takes all this into account.
A clock face has 60 minutes (time) which is 360* (angle), hence each minute (time) on the clock face is equivalent to 6 degrees (angle).
Therefore your -17.5 degrees is where the minute hand would be at approx 3 minutes past the 12 o'clock position.This is when looking into the dish from the lnb.
The negative figure is because your dish looks up at the signal from the satellite and consequently the lnb would be skewed over to be approx 3 minutes (time) before the 12 o'clock position if looking up from the rear of the dish.
To be honest it is not really worth the trouble in the UK, but for those in marginal reception areas every little helps. The ideal situation would be to cant your dish over at 17.5 degrees as this happens with a motorised system.
Hope that this has helped.
H-B
 
H

Happy-Buddah

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@ zorba

No m8, it is purely to do with your location on earth in respect to where the satellite is.
H-B
 
H

Happy-Buddah

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@ devonbrown

It would be interesting to know your rough location to come up with that figure I reckon that you must be somewhere below the horizon???
H-B
 

Zorba

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Happy-Buddah said:
@ zorba

No m8, it is purely to do with your location on earth in respect to where the satellite is.
H-B
Well I never !I was actually joking,hence the laughing emoticons after my statement. :rolleyes:
As a matter of interest,to get 28.2 over here we are just a couple of degrees of south on the compass, so if i moved down the longitude to right on the equator(somewhere in Africa I think) then my dish(prime focus) would point almost straight up to the sky.Now I know why there is a hole in the middle.to let the rain out O-Ha
 
H

Happy-Buddah

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Hi zorba

If you moved down to the equator you would miss being under the Astra cluster but the bird at 33* east could drop an egg on you m8.:D
Yes centre fed dishes as against offset tend to have a hole in the centre, it relieves some stresses during manufacture and helps drain water out when pointed high. The 90-100 ft dishes at our earth station teleports had 6 inch pipes in the centre to drain off water, as they were put on their backs for repairs/maintenance etc. Many a spanner/screwdriver/nut/bolt/washer did I loose in the past by them rolling down the "spout".
And I envyyou living in sunny Cyprus whilst I'm in snowy Suffolk (LOL ;) ;) ) or have you had a dose of bad weather over there also?
Regards
Happy-Buddah
 

iceman

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For those who dont already have it in their favorites list this is a usefull relevant site.
http://www.satellite-calculations.com/

iceman
 

devonbrown

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Happy-Buddah said:
@ devonbrown

It would be interesting to know your rough location to come up with that figure I reckon that you must be somewhere below the horizon???
H-B
I am in the Costa del Sol.
 
H

Happy-Buddah

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@ devonbrown

For that location, 6 minutes past the hour looking into the dish from the lnb, and yes you are well below the uk horizon.
regards H-B
 
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