LNB skew setting - motorised installation - Techwatch Support Forums: Digital & Satellite TV, FTA, Cable, Computers, Mobile Phones, Apple and General Tech Forums

ferrymanr · 02-08-07, 09:46 AM

Just to clarify my position: I have not played with satellites for 15 years or so. I had a system with two LNBs on a polarisation splitter (one LNB for vertical and one for horizontal) and a polarotor to adjust skew, that way polarisation adjustment was a wheeze. I still have the old (analogue) receiver with a current feed for the polarotor!

My new system is a 90cm offset dish on a small motor with cranked arm and DiSEqC control. I have an LNB set at zero degrees skew as I assumed the dish movement would retain the correct skew for all satellites. However this does not seem to be quite correct. I also read that the Astra birds have a slightly different polarisation to other birds.

So what is the best way to set up my LNB?

Thanks
Richard

Jimdefruit · 02-08-07, 09:56 AM

Welcome to the forum ferrymanr.

Have you got the dish/motor/receiver to see all satellites that are line of sight available?

If you have set up the dish/motor correctly with the high point on your south most satellite then there should not be a problem with skew.

If you are not getting a good signal and you know you are traversing the satellite arc, then by all means try adjusting the skew but normally it should not be necessary.

ferrymanr · 02-08-07, 10:29 AM

Thanks jimdefruit.
I have horizon to horizon coverage that works well to at least +/- 50 degrees.
Although the skew seems a little different for Astra I get a massive signal anyway. I might just as well leave the LNB at my original setting (I checked that on the bird at 1W, being nearest South).
Richard

Jimdefruit · 02-08-07, 11:09 AM

That sounds fine. The skew automatically changes as the dish moves around the arc.

BGonaSTICK · 02-08-07, 09:44 PM

I've not heard anything about the skew being slightly different for Astra sats? :? I'm interested - do you have a source for that info?

Polarotors are not in common use today as you've probably found out. The latest satellites are so powerful you could find them on a saucepan lid underwater.

madrat · 06-08-07, 12:32 AM

Quote:

The latest satellites are so powerful you could find them on a saucepan lid underwater

A prize will be awarded to the fist member to achieve this :roflmao:

02-08-07, 09:46 AM	#1 (permalink)
ferrymanr Junior Member Join Date: Jul 2007 Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	LNB skew setting - motorised installation Just to clarify my position: I have not played with satellites for 15 years or so. I had a system with two LNBs on a polarisation splitter (one LNB for vertical and one for horizontal) and a polarotor to adjust skew, that way polarisation adjustment was a wheeze. I still have the old (analogue) receiver with a current feed for the polarotor! My new system is a 90cm offset dish on a small motor with cranked arm and DiSEqC control. I have an LNB set at zero degrees skew as I assumed the dish movement would retain the correct skew for all satellites. However this does not seem to be quite correct. I also read that the Astra birds have a slightly different polarisation to other birds. So what is the best way to set up my LNB? Thanks Richard

02-08-07, 09:56 AM	#2 (permalink)
Jimdefruit Super Moderator Join Date: Jan 2006 Posts: 2,858 Thanks: 20 Thanked 221 Times in 187 Posts	Re: LNB skew setting - motorised installation Welcome to the forum ferrymanr. Have you got the dish/motor/receiver to see all satellites that are line of sight available? If you have set up the dish/motor correctly with the high point on your south most satellite then there should not be a problem with skew. If you are not getting a good signal and you know you are traversing the satellite arc, then by all means try adjusting the skew but normally it should not be necessary. __________________ Dreambox 800 HD; Dreambox 7000s + VBox + Channel Master 1.2 with 36v actuator CM120 feedhorn and Invacom .3 LNB Skystar 2 PCI card with links to my Dreamboxes If you like what you see here, tell your friends.

02-08-07, 10:29 AM	#3 (permalink)
ferrymanr Junior Member Join Date: Jul 2007 Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	Re: LNB skew setting - motorised installation Thanks jimdefruit. I have horizon to horizon coverage that works well to at least +/- 50 degrees. Although the skew seems a little different for Astra I get a massive signal anyway. I might just as well leave the LNB at my original setting (I checked that on the bird at 1W, being nearest South). Richard

02-08-07, 11:09 AM	#4 (permalink)
Jimdefruit Super Moderator Join Date: Jan 2006 Posts: 2,858 Thanks: 20 Thanked 221 Times in 187 Posts	Re: LNB skew setting - motorised installation That sounds fine. The skew automatically changes as the dish moves around the arc. __________________ Dreambox 800 HD; Dreambox 7000s + VBox + Channel Master 1.2 with 36v actuator CM120 feedhorn and Invacom .3 LNB Skystar 2 PCI card with links to my Dreamboxes If you like what you see here, tell your friends.

02-08-07, 09:44 PM	#5 (permalink)
BGonaSTICK Dodgy Geezer Join Date: Nov 2005 Location: Brighton Posts: 9,718 Thanks: 3 Thanked 166 Times in 60 Posts	Re: LNB skew setting - motorised installation I've not heard anything about the skew being slightly different for Astra sats? :? I'm interested - do you have a source for that info? Polarotors are not in common use today as you've probably found out. The latest satellites are so powerful you could find them on a saucepan lid underwater. __________________ Dreambox 7000, Skystar2 PCI, Skystar USB, Fibo 90cm on Moteck SG2100, Triax TD110 multi-LNB. Sky + ART cards. 45.0°E - 58.0°W