MOSLAVINA

Hi all,

New member , frst post.

I have recently re-aquired foxtel. i bought my home with an existing dish(seems original) i have confirmed it's foxtel although the lnb was damaged in hail storms so i went to hotchip and got a new sharp ku lnb.

i neglectyed to take dfown the lnb skew setting priot to removal and with the new lnb i dont know what it should be on and which direction to turn the lnb as i am facing the dish! i have set it to 45 degrees turning the lnb to the left so the pointer is 7 notches to the right from centre.

is this right? what should it be?

do i need t re-align my dish or is it ok as it hasn't moved from original spot from day 1?


appreciate any help

John.

reply to group or
e_llusion82@hotmail.com

LeroyPatrol

I don't know what it should be but start with the connector pointing to around 7 o'clock when looking into the dish. With your sat reciever on the signal strength screen, watch happens when you turn the lnb and adjust it for maximum signal and quality.
While you are at it you could check to see if you dish is well aligned. While watch ing the signal strength screen push on the top, bottom, lhs and rhs of the dish to see if the signal goes up or down. If the signal goes up when you push then the dish needs to be adjusted in that direction a little. Keep doing this till you get your dish adjusted for best signal.
Have fun,
Leroy

mborkp

Hi,
should all kind of LNB be skew for C1? What about D2 (ex. B3). My signal goes around 80 and I think should be better than that ?

Thanks,
mbo

beer4life

G'day Everyone,
All current Optus Satellites have that preset skew of about +40 deg.
When looking into dish, LNB needs to be turned clockwise from normal.
With one exception. Some of the early Foxtel/Austar LNBs had that skew built in.
On these you will see a molded arrow about 40 deg C/W from the normal setting.
If you want to use one of these for other Sats, turn anti C/W until arrow is vertical.
I've attempted to show this in followimg image.
There is a bit of parallax error showing, but is 40 deg.
These may be quite rare now, but be aware that it is still possible to find them.
Kindest Regards, " The Druid ".

http://img204.imageshack.us/my.php?image=dig2001yn2.jpg

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MOSLAVINA

Thanks guys,

I had a mate inside watching the signal screen (foxtel digital/pace box) and i tried all adjustments from dish vert/horiz to lnb degrees and even lnb seat(in or out) i mean the lnb position in the holder closer to dish out further away (1 inch variation).


i found that i got a maximum 78dbu signal strength and a 3/4 signal quality. i hjave been watching foxtell on my old 65cm dish (paint peeling and all) with a new sharplnb $30 from hotchip and its good hasnt dropped out at all running YUV out into my av system via scart the yuv to my tv.

i have found that all 65cm dishes in sydney due to the size of the recieving area usually get only approx 77dbi and if i push the lnb towards the dish i get stronger signal(aligns lnb to centre of dish) if i turn it anti clockwise i get bad/no signal but clockwise anything from 5 degrees to approx 60 degrees seems to be 76 - 78 dbi. works well for me well good enuf for euro soccer anyway.

thanks for your help

beer4life

Absolutely fantastic what true fanatics will endure to watch their favorite sport.
Kindest Regards, " The Druid ".

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mborkp

beer4life,
thanks a lot for this important info!
Will have to jump on my roof tommorow and use my new gadget to play with dish setup.
Regards,
mbo

AfterHourZ

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AfterHourZ

Dreambox Nut

beer4life

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mborkp

Hi,
would be 40deg skew also valid in Perth or it is different value here?

Cheers,
mbo

biggeorge

I don't know about the skew angle or any of that stuff, but for a sharp LNB you turn it so the cable sticks out towards the east a bit and if you look at the notches in the top of the LNB the 3rd one from the end should line up with the middle of the LNB mount at the top.

This is applicable for all optus satellites with sharp LNBs.

Farmsky

Dear fellow,

I'm not sure where you have 'learnt' your extremely limited and always misleading information on satellites ....... but you are ...... simply full of it!

The 'Hills Gemini Satellite dish alignment settings' guide posted earlier by After Hour Z is spot on; as you would expect from a major industry supplier like Hills.

As I have explained elsewhere the Optus series satellites are tilted on their flight axis wrt other satellites. The actual tilt or variation from a standard skew is not 40 degrees. Rather it is 45 degrees.

Stare up at the sky and imagine the Clarke Belt spreading in an arc from east to west. Imagine a point at the apex of the arc ie due north. Now a satellite here would normally be vertical. If it is an Optus satellite it is tilted 45 degrees to the left. That's what the Optus 'mystery' is about. Of course this put's it midway between vertical and horizontal if you are aligned for a 'normal skew' satellite.

So the trick when using any dish pointing software is to simply 'add on' the special Optus skew (45 degrees).

The correct skew setting for Sydney OPTUS C1 is +38 degrees which is where I suspect poor old beerforlife's 40 'Sydney centric' view comes from.

But what does this mean?

Looking into the dish (Sydney), the lnb is rotated 38 degrees clockwise from vertical. ie starting with the cable exit point down (6 o'clock). 38 degrees is a bit past 7 0'clock (30 degrees) which is the common reference we generally talk about for C1 in Sydney. The lnb's manufacture's tolerance may vary this a bit, even between like lnb's.

The other main Optus birds will have slightly different skews in Sydney. e.g

Optus D2 (152 E) Skew = 44 deg
Optus C1 (156 E) Skew = 38 deg
Optus D1 (160 E) Skew = 32 deg

..... But all still pretty close to 7 o'clock

The following explanation will completely lose beerfor life; but bear with me.

An excellent dish pointing skew calculator is available at satlex. Have a look at this site and plug in various satellites and locations. You will notice how the skew changes with satellite and location. If you can get your head around it; this site and the nice graphics will also explain why the skew varies with satellite and location. It should also give you an insight as to why the skew is 'automatically adjusted' on a polar mount as you 'roll' around the Clarke Belt.

However the Satlex site (and none of the web calculators that I know of apart from the published calculators like Hills), take into account the different Optus skew.

So this is how you calculate it using a standard dish pointer.

Satlex indicates +7.1 deg for Optus C1 in Sydney. So 7 - 45 = -38 degrees (or a bit past 7 0'clock). Which by the way matches the Hills chart.

Note: +/- skew depends on how you look at the skew rotation. There does not appear to be a standard nomenclature here.

So what about Perth?

Satlex indicates +46 for Optus C1 in Perth. So 46 - 45 = 1 degree (or 6 o'clock). Which again perfectly matches the Hills chart.

And if you want it from the horse's mouth, here is Optus's neat little skew chart for Optus C1 from the 'Optus Satellite Network Designers Guide'.



And they provide them for all their orbital slots.

punjabiz

Farmsky,

Very nicely written!!...

Cheers

LeroyPatrol

I always enjoy your in depth responses to questions Farmsky.

Leroy

beer4life

You've been itching to have a crack at me since I returned to the forum.
You're expertise would be more constructive if used to help members rather than flame them with your convoluted diatribe.
Your main gripe here is misquoting me about the Optus skew.
I've used the nomenclature of Preset Skew for Optus Satellites. The figure of 40 Deg. came from an old LNB with a moulded arrow. Near enough to all intents and purposes.
Now you are inventing nomenclature for figments of your imagination that I never said or intimated.

Quote:

The correct skew setting for Sydney OPTUS C1 is +38 degrees which is where I suspect poor old beerforlife's 40 'Sydney centric' view comes from.

The preset skew is set with the dish pointing True North.There is a difference (Perth 4 W) and (Sydney 12 E) of 16 Degrees in "Magnetic Variation (Declination)".
There are places on our planet exceeding + or - 45 Deg. Magnetic Variation.

Satellite Footprints by Dish Size - Magnetic Deviation Maps - Global and North America, South America, Europe, Middle East, Orient/New Guinea, Australia/New Zealand
You do not have the faintest idea of Navigation.
I, on the other hand have been a 'Licenced Navigator' for 58 years.
To use any of the composite satellite charts for all sats, quoted skew must be taken into account as well as any "Preset Skew".


May I humbly suggest, that instead of posturing as the only GURU on the forums, that you accept help from others as it is intended, and if necessary politely and diplomatically disagree or reinforce.

Very Kindest Regards, " The Druid ".

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*fergs*

On what satellite ??

just got on the roof & looked @ my C1 & the cable exit from LNB is about 5 oclock...

if thats any help... (acer lnb i think)

Farmsky

I'll let others be the judge

beer4life

The "Preset Skew", despite the 'red herrings' is set with the Mast plumb, the motor if used, central and the azimuth at North. North True, not Magnetic.If you follow others' description(7'0Clock for exit cable),(nearer 7.30 to be precise).
The "Preset Skew" remains the same irrespective of your azimuth.
Kindest Regards, " The Druid ".

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beer4life

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punjabiz

WoW!... dude how old are you?

Nevertheless, Always good to see experienced sharing their experience/knowledge