LNB Skew

dave branson

Regular Member
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My Location
Florence Italy
#1
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

Specialist Contributor
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#2
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

Regular Member
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My Location
Florence Italy
#3
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

Specialist Contributor
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224
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My Satellite Setup
4 systems. In Scotland Freesat with Humax Foxsat recorder. In Algarve 1.5 fixed Inv Quad LNB with 3 Pace 2600C1 and 1 Amstrad HD DRX780UK also 80cm dish with Inverto 0.2db monoblock LNB (19.2E/26E) feeding Technomate 5000CI+ usb.
My Location
Scotlandl and Algarve
#4
Is the angle given at this site (mine is -35.86) as viewed from the dish or towards the dish?
 

rolfw

Believe it when I see it Admin.
Staff member
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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
#5
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

aka Skyman
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My Satellite Setup
3m(28.2E),1.5m(19.2E.13E,10E),1m (4W ,7W)1m (?).diseqc 10,sky plus,VU+,telergy iptv.
Satlook nit colour + Horizon hdsm.
My Location
Limassol, Sunny Cyprus
#6
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

Regular Member
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My Location
Florence Italy
#7
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

Guest
#8
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

Guest
#9
@ 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

Guest
#10
@ 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

aka Skyman
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My Satellite Setup
3m(28.2E),1.5m(19.2E.13E,10E),1m (4W ,7W)1m (?).diseqc 10,sky plus,VU+,telergy iptv.
Satlook nit colour + Horizon hdsm.
My Location
Limassol, Sunny Cyprus
#11
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

Guest
#12
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

Specialist Contributor
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3.0m Motorised Channel Master + 4 fixed dish Amstrad_DRX890C
DM7020s,DM800se
UNOHM EP314 PROMAX TV Explorer
My Location
Kyrenia - NORTH CYPRUS
#13
For those who dont already have it in their favorites list this is a usefull relevant site.
http://www.satellite-calculations.com/

iceman
 

devonbrown

Specialist Contributor
Messages
224
Likes
1
My Satellite Setup
4 systems. In Scotland Freesat with Humax Foxsat recorder. In Algarve 1.5 fixed Inv Quad LNB with 3 Pace 2600C1 and 1 Amstrad HD DRX780UK also 80cm dish with Inverto 0.2db monoblock LNB (19.2E/26E) feeding Technomate 5000CI+ usb.
My Location
Scotlandl and Algarve
#14
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

Guest
#15
@ 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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