LNB and Dish matching to the receiver

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ivorlink

2 posts

Wannabe Geek

#53866 14-Dec-2009 23:06

Hi to all - I am a new immigrant to New Zealand and trying to put a TV Sat / Freeview combination together. I have bought a DS200 receiver and am now looking to find what the pros & Cons are for the dish sets. Namely: Should I buy a single 11.300GHz LO Frequency LNB or an aluminum Ku Band LNB 1075MHz? Or anything better? I know nothing about the matching and need advice. I will be using the system in my caravan for touring NZ and will eventually want to add it to my house when I settle down afterwards.
Thanks to anyone who can steer me in the right direction.
Ivor

kiwisat

147 posts

Master Geek

#282877 15-Dec-2009 19:39

You might be interested in this auction, http://www.trademe.co.nz/Browse/Listing.aspx?id=259642165 which may suit your needs. I am the vendor in this instance so I am obviously biased but i have had positive response from all who have purchased.

allstarnz

1719 posts

Uber Geek

Trusted

#282884 15-Dec-2009 19:51

if you have a choice between a 10750 and an 11300 LNB, take the 10750, it's got better frequency range.

ivorlink

2 posts

Wannabe Geek

#282900 15-Dec-2009 20:34

Thank you for your advice. I hear that a 60cm dish is optimum for weather / rain fade?

kiwisat

147 posts

Master Geek

#282950 15-Dec-2009 22:14

I can guarantee that a 45 cm dish is more than enough for the NZ beam from Optus D1. If you take a look at this footprint map, http://www.lyngsat-maps.com/maps/optusd1_nzb.html , we should all be wearing hats, but as is indicated in the side bar, a good 45 cm dish is all that is required.

One obvious benefit is the wider beam width of the smaller dish, allowing faster acquisition of the satellite, very important for travellers.

Fine tuning to a weaker channel such as SBS guarantees no rain fade on all the NZ services.

Sometimes bigger is not necessarily better.

Jaxson

8042 posts

Uber Geek

Trusted

#283034 16-Dec-2009 09:39

kiwisat: Fine tuning to a weaker channel such as SBS guarantees no rain fade on all the NZ services.

Could you elaborate on this please?
I would have initially thought a bigger dish would catch more of the incoming signal, so would be more tolerant of a less than perfect aligment?

kiwisat

147 posts

Master Geek

#283085 16-Dec-2009 12:37

Basically the SBS signal is carried on a NZ and Australia beam of the satellite and is polarized Vertical.
Reception of this signal requires the LNB skew to be fine tuned and this in turn ensures the dish is targeting the satellite perfectly hence the NZ beam will also be perfectly aligned. Many Sky installs have not had their skew adjusted for the vertical beam hence rain fade on the larger Sky dishes.

Hope this helps.

Jaxson

8042 posts

Uber Geek

Trusted

#283089 16-Dec-2009 12:52

Sorry, crap I highlighted the wrong line. I get the use of SBS to fine tune, it's a bloody good idea given the signals are weaker than the main freeview broadcasts off D1.

No, was meaning the other bit, could you clarify this please:

One obvious benefit is the wider beam width of the smaller dish, allowing faster acquisition of the satellite, very important for travellers.

Sharesies

Trade NZ and US shares and funds with Sharesies (affiliate link).

allstarnz

1719 posts

Uber Geek

Trusted

#283092 16-Dec-2009 13:13

buy as big a dish as is practical. smaller dishes are prone to rain fade, and also have trouble picking up the weaker channels. SBS is significantly weaker than Freeview, with it dropping out for me when it's really cloudy or bucketing down.

kiwisat

147 posts

Master Geek

#283210 16-Dec-2009 20:01

"One obvious benefit is the wider beam width of the smaller dish, allowing faster acquisition of the satellite, very important for travellers".

Essentially, the bigger the dish, the narrower the beam width. The higher the frequency and the larger the antenna, the more narrow the beamwidth, so therefore a 2 metre reflector will have one half the beamwidth of a 1 metre reflector. Without wishing to confuse the issue here, it also follows that a Ku band antenna will have one third the beamwidth of a C band antenna, because the Ku band frequencies are 3 times higher.

A minimum 2 degree separation between satellites is maintained to avoid interference from one satellite to another. As it stands now, there is very little adjustment required to move from Optus D1 to Optus C1, which are 4 degrees apart.

I only lose SBS when is is bucketing down, but still hold Freeview.