Multi LNB setup

[wazm]

OK, after a lot of thought and looking at fairly large dishes, I got this one only with out the multi LNB setup as I have already bought one.

The dish is 85cm and wide! Can anyone tell me the theory behind the multi LNB. I have the pictures of LeyroyPatrol's but that doesn't tell me a couple of things. Do the extra LNB's point to the same place on the dish as the original positioned one? Also, I have jury rigged the multi setup like in the pictures only a bit more temporary.

How do I find D2? I have the main on C1. Is there a quick way? I just spent 30 frustrating mins moving the lnb round and round to get no movement in signal. Is there a short cut like if the sat is higher the lnb is higher sit the lnb higher than the original etc? Can anyone save my sanity? lol

Cheers,

Warren

[mtv]

OK, after a lot of thought and looking at fairly large dishes, I got this one only with out the multi LNB setup as I have already bought one.

The dish is 85cm and wide! Can anyone tell me the theory behind the multi LNB. I have the pictures of LeyroyPatrol's but that doesn't tell me a couple of things. Do the extra LNB's point to the same place on the dish as the original positioned one? Also, I have jury rigged the multi setup like in the pictures only a bit more temporary.

How do I find D2? I have the main on C1. Is there a quick way? I just spent 30 frustrating mins moving the lnb round and round to get no movement in signal. Is there a short cut like if the sat is higher the lnb is higher sit the lnb higher than the original etc? Can anyone save my sanity? lol

Cheers,

Warren

The best dish for multi LNB use, is a toroidal dish, as it's designed specifically for the purpose, however, multi LNB setups can be done with standard dishes.

You first need to learn the position of the satellites, so you know where you need to be pointing a dish/LNB.

D2 is a little higher and a little to the west (to the left) of C1/D3 when viewed from behind the dish.

The LNB's need to 'cross over' and be angled for both azimuth and elevation.

The diagram from beer4life illustrates this concept well.




Perhaps before attempting multi LNB's... try finding the various sats with a single LNB, that way you'll get the feel for where they are in relation to your location.

[LeroyPatrol]

The best dish for multi LNB use, is a toroidal dish, as it's designed specifically for the purpose, however, multi LNB setups can be done with standard dishes.

MTV, That's actually a Jonsa multi lnb dish not a std 85cm dish. Leroy

[mtv]

MTV, That's actually a Jonsa multi lnb dish not a std 85cm dish. Leroy

Yep.. it has a wider angle than 'standard' dishes, but essentially a conventional design, compared to a toroidal dish, which has a sub-reflector.

[wazm]

Thanks for the quick reply mtv. I have that diagram printed out and had it out in the yard with me while I was playing with the dish but didn't help me so I guess I am a bit thick . I have found all of the sats using a single lnb without probs. I am still a bit thick remember lol. Does the signal reflect from the center of the dish for every lnb or off to different angles and positions on the dish for each lnb?

[beer4life]

OK, after a lot of thought and looking at fairly large dishes, I got this one only with out the multi LNB setup as I have already bought one.

The dish is 85cm and wide! Can anyone tell me the theory behind the multi LNB. I have the pictures of LeyroyPatrol's but that doesn't tell me a couple of things. Do the extra LNB's point to the same place on the dish as the original positioned one? Also, I have jury rigged the multi setup like in the pictures only a bit more temporary.

How do I find D2? I have the main on C1. Is there a quick way? I just spent 30 frustrating mins moving the lnb round and round to get no movement in signal. Is there a short cut like if the sat is higher the lnb is higher sit the lnb higher than the original etc? Can anyone save my sanity? lol

Cheers,

Warren

G'Day Warren,
Methinks this should help you understand the principle.


As well as that, they also need to cross over vertical as viewed from your location.
If the Satellite is higher elevation than another, it must sit lower in the bracket. All LNBs should aim at the centre of the dish, with elevation crossovers. For closely spaced Satellites, this is a small difference.
The actual crossovers will vary whether you are in NZ or WA.
Without Knowing your location, hard to advise, but this should clear up the mystery.
The Clarke Belt appears as a parabola from your location with the peak at Due True North from your longitude location.

Kindest Regards, " The Druid ".

[wazm]

Without Knowing your location, hard to advise, but this should clear up the mystery.

Hi, I am in Bathurst NSW.

[dam0]

ive got the same dish and took me a while to figure it out. i found it best to set up c1/d3 in the centre get that tuned and go from there.


Uploaded with

[mtv]

Does the signal reflect from the center of the dish for every lnb or off to different angles and positions on the dish for each lnb?

Only the centre LNB receives signals reflected from the centre of the dish, but being an offset dish, even that one is at an angle upwards.

All the other LNB's either side of the centre one will be angled across and upwards. The amount of angle will depend on which satellite it's looking at.

That diagram doesn't show one LNB in the centre, but 4 spaced LNB's.

Look at the diagram showing the D2 LNB... it's on the left of centre when viewed from the front of the dish, so it's accepting signals reflected from the right of the dish, when viewed from the front... when viewing from behind the dish, naturally you have to reverse left/right.

Now look at the angle... it's pointing across the dish slightly and although you can't tell from the diagram, it would also have to ba angled a little higher than the C1/D3 LNB, bacause D2 is a little higher in the 'arc' of the Clarke Belt.

What are you using to locate the satellites.... a satfinder in conjunction with watching the signal scales from a decoder on a screen?

[LeroyPatrol]

Thanks for the quick reply mtv. I have that diagram printed out and had it out in the yard with me while I was playing with the dish but didn't help me so I guess I am a bit thick . I have found all of the sats using a single lnb without probs. I am still a bit thick remember lol. Does the signal reflect from the center of the dish for every lnb or off to different angles and positions on the dish for each lnb?

If you have your centre lnb on Optus C1 at 156 deg, then as you look in the sky you'll have D2 at 152 deg to the left of C1 and D1 at 160 is to the right of C1.
Looking at the Beer for boof heads diagram, if you follow the lines from the round dots that are the sats, they 'reflect' on the dish to the LNB location. The reflection will be symetrical because the sats are 4 deg apart. Also the LNB's on either side of the LNB will be angled towards the centre a little and will not be in a line but angled in the holder. It's raining so I can't check to see which way but look at the pic of my setup that you have to give you an idea.

Edit: here you can see in the second pic D2 is on the left and Is8 on the right. On my setup i centred on C1.


Leroy

[beer4life]

Hi, I am in Bathurst NSW.

G'Day Cobber,
This will be basically the same from Bathurst, with the satellites of interest to the East of you.
As you can see, the elevation of each Satellite differs with Longitude.
I hope this sorts out your mysteries.
To the best of my knowledge, that Jonsa dish was not designed for multi LNBs, but is as good as, or even better for that application.
Since all LNBs are aimed at the centre of the dish, it is immaterial.



Kindest Regards, " The Druid ".

[wazm]

What are you using to locate the satellites.... a satfinder in conjunction with watching the signal scales from a decoder on a screen?

I have a sat meter and a Satlink WS-6902. I will give it another go tomorrow. Thanks for the help.

[wazm]

ive got the same dish and took me a while to figure it out. i found it best to set up c1/d3 in the centre get that tuned and go from there.

Thanks, that picture is worth a thousand words and explains a lot. I will try and emulate it tomorrow and see how I go. I read a lot about this on the net and it gets very confusing when they stay talking about dish skew.

[beer4life]

If you have your centre lnb on Optus C1 at 156 deg, then as you look in the sky you'll have D2 at 152 deg to the left of C1 and D1 at 160 is to the right of C1.
Looking at the Beer for boof heads diagram, if you follow the lines from the round dots that are the sats, they 'reflect' on the dish to the LNB location. The reflection will be symetrical because the sats are 4 deg apart. Also the LNB's on either side of the LNB will be angled towards the centre a little and will not be in a line but angled in the holder. It's raining so I can't check to see which way but look at the pic of my setup that you have to give you an idea.

Edit: here you can see in the second pic D2 is on the left and Is8 on the right. On my setup i centred on C1.


Leroy

OOPs, seems to me you need a GPS unit to find your left and right hand.

[LeroyPatrol]

OOPs, seems to me you need a GPS unit to find your left and right hand.

It's ok, I know it's confusing. If you reread you may, may being the operative word, understand.

Leroy

[Mysterex]

the dish is aligned to C1/D3 but the C1/D3 LNB is removed as it intersects with the D1 LNB

[wazm]

the dish is aligned to C1/D3 but the C1/D3 LNB is removed as it intersects with the D1 LNB

Hi, This is exactly what I am trying to do. I have an Austar dish on the roof so I don't need to point anything at C1/D3 and the sats you are pointing at are the sats I would like to point at. I have a print out of this picture and as the dish I have looks very similar to yours and I have the same multi setup as you have, I will see if I can duplicate your setup. I have the dish pointing at C1/D3 now so that is a head start .

Thanks everyone for the help. It has all been invaluable!

Warren

[mtv]

Interesting difference in LNB skew of the D1 and D2 LNB's in the pic, Mysterex.

Is it that those two LNB's have different skew settings relevant to the output connector, or is there another reason for the difference?

[Mysterex]

updated pic from today... showing correct skew (old pic was from when i was still setting up after aligning each lnb)

yes its still looks out compared to D2 lnb but its peaked for the best signal quality - i think its probably the different lnb i used for D1 - the label is long gone but its a die-cast metal bodied lnb but doesn't match other Hills branded lnbs i've got...

[mtv]

Possibly an old Acer LNB.. 11300?

The dish has weathered badly.... wouldn't be helping reception much.