Receiving KU sats East and West on a moving dish

wium

Regular Member
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My Satellite Setup
C and Ku
My Location
South Africa
#1
What do i require to account for the change in skew on East and West satellites?
 

rolfw

Believe it when I see it Admin.
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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
#2
Each satellite will be different. Polarmounts and diseqC motors account for skew, but sometimes a little extra adjustment is required. What type of system are you using?
 

wium

Regular Member
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My Satellite Setup
C and Ku
My Location
South Africa
#3
At present on my fixed dish on Telstar 12,15 West, my skew is on 8 o,clock and turning the dish to Pas 10, 68.5 East my skew must be adjusted to 4 o,clock.I am setting up a motorised polarmount and wish to know how to handle the skew adjustment.
 

Topper

Amo Amas Amant Admin
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My Satellite Setup
IDD CI24 ECONO MM Penta 1.20 Galaxy II
1.2Mtr Polar MTG yes it has been on the arc for 25 years and is now fixed on 13 East using two pairs of rusty molegrips. Unlike me they never groan but always perform.
My Location
Blackburn, Lancashire
#4
Surely your polar mount takes care of any skew adjustment automatically, mine does!
 

wium

Regular Member
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My Satellite Setup
C and Ku
My Location
South Africa
#5
Thanks Topper.I have mounted my 90CM offset dish onto a polar mount and enquire how i account for the measurements as my dish has a built in offset angle of 22 degrees.Where i am my latitude is 34 with a declination of 5.
 

Topper

Amo Amas Amant Admin
Staff member
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My Satellite Setup
IDD CI24 ECONO MM Penta 1.20 Galaxy II
1.2Mtr Polar MTG yes it has been on the arc for 25 years and is now fixed on 13 East using two pairs of rusty molegrips. Unlike me they never groan but always perform.
My Location
Blackburn, Lancashire
#6
Having thought about this I am either going to make it clear what is happening here or make myself look like a complete pratt.....the latter is more probable:)
I hope I can explain this clearly and make you understand, I think I am correct in saying for you E & W would be reversed on this diagram if you are in the southern hemisphere (which I think you are?).

If you took the diagram below (reversed East and West)and put it in front of your dish this gives you the direction of rotation of the lnb for what is known as skew. Whilst obviously the arc of the geostationary satellites as viewed from earth is exaggerated for the purposes of clarity in this drawing this will give you the general idea. Thus from where you are the satellite that is directly due north of your position will have zero skew to the East the lnb rotates anticlockwise and clockwise for West. As to how that is calculated, I have not a clue, like I said my mount does it for me.
The second picture just gives you an idea of the actual angle of the signal path for an offset dish, hope this helps
 

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wium

Regular Member
Messages
147
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My Satellite Setup
C and Ku
My Location
South Africa
#7
Thanks Topper i fully understand the concept.
Is there anyone who have done a similar installation ie 90CM offset dish mounted on a polar mount and driven with an actuator who can possibly give some guidelines and direction.Being in the Southern hemisphere i assume the starting point would be to rotate the LNB for a zero skew on the most northern satellite.Will zero be when the cable connector of the LNB face downwards at 90 degrees.?
Any assistance given will be greatly appreciated.
 

Topper

Amo Amas Amant Admin
Staff member
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21,783
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My Satellite Setup
IDD CI24 ECONO MM Penta 1.20 Galaxy II
1.2Mtr Polar MTG yes it has been on the arc for 25 years and is now fixed on 13 East using two pairs of rusty molegrips. Unlike me they never groan but always perform.
My Location
Blackburn, Lancashire
#8
wium said:
Is there anyone who have done a similar installation ie 90CM offset dish mounted on a polar mount and driven with an actuator who can possibly give some guidelines and direction.
Please show a picture of your setup, after setting for your due north satellite everything else should fall into place, have you read the stickies (red dot posts) at the top of this section?

wium said:
Being in the Southern hemisphere i assume the starting point would be to rotate the LNB for a zero skew on the most northern satellite.Will zero be when the cable connector of the LNB face downwards at 90 degrees.?
Any assistance given will be greatly appreciated.
Again let us see a photo of the lnb
 

wium

Regular Member
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My Satellite Setup
C and Ku
My Location
South Africa
#9
Noted Topper.
I am not into cameras but have checked my dish with another Lnb to satisfy myself that i am receiving a picture when the dish is fixed onto a satellite.My problem is that i do not have a satellite above my true north position, the nearest being 21 degrees to the left and 27 degrees to the right(Southern Hemisphere)I dont think the stickies cover the mounting onto a polar mount (home made)There must be someone out there who has done something similar.
 
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