C band multi lnb arm

[dssnosher]

Greetings,

In the process of setting up a 300 cm mesh to receive Intelsat 17 @ 66E but also interested to receive Intelsat 20 @ 68.5E on the same dish.

Now the multi-lnb set up is quite easy with the KU band but for C based on my research it's a bit different. First two things that come into unknown is where to get the C band arm to attach a second lnb and what is the best practice setting up multi-lnb for C band.

Any insight and help would me very appreciated.

 

[Vipersan]

On such a big dish something like this would be useful ..though finding a supplier might be tricky ..
China or India is yer best bet ..
They come in dual ..triple or quad flavours ..
rgds
VS

 

[Terryl]

The big problems with a standard "C" band dish in trying to setup multiple LNB's on it is the fact that they don't have very good side to side reception.

An LNB mounted to the right or left of dead center may have signal problems, as the dishes focal area is round, (like the dish) and not elliptical, the dish would need to be shaped like a big radar dish (somewhat) to get usable signals to the side mounted LNB's, and I haven't seen one like that around for many many years.

This is why most are motorized to pan left or right.

Now I'm not saying that it may or may not work, you would have to test this by moving the dish ever so slightly left or right to see how far down your signal drops, take note of how far it can be moved to see how large a focal area you have with that dish, you may need to remove the Scala ring (if you can) to see this. as that is for side rejection of unwanted signals.

This may be why the setup posted by Vipersan does not have one.

 

[Terryl]

One other thing, I don't know if you can get the two "C" band LNB's close enough together to get two satellites spaced only 2.5 degrees apart, there may be some cutting of the sides of the LNB involved.

 

[Vipersan]

...As Terry says ..this is a problem with side by side grouping of C band lnbs at the focus of a PF dish ..
All is compromise ..
I built my own with cut scalar rings ...such that both lnbs could be as close as practical or possible ...
Neither occupies the 'sweet spot' ..but indeed ..share the focus ...which is actually between the 2 lnbs ...
Thus both lnbs are about 2 degrees off focus...
That's _my_ compromise..
cest la vie.