Multi LNB Spacing

[sharpee]

Hey Guys,
I was wondering if it's possible to to use 2 lnbs spaced 2.5 deg instead of the recommended 3 deg. I'm interested in adding a second lnb on my Telstar12 dish for reception of Atlantic Bird 1. Would that be possible??
Well, winter is just around the corner (I Hate it when its too windy and cold to get on the dish roof!) and i want to get some dish work done.
Thanks

 

[Mr Tony]

Highly unlikely. Most LNB's are 4 degree spacing if you put them right next to each other

 

[VinceT3]

Can't you buy a few 119/121 lnbs from dish .. ebay has em for a reasonable price.. you should just need to change out one of them for a non-dbs lnb..

was going to test that out with the toroidal dish at some point..

 

[sharpee]

OK Iceberg, I think I get it. So normal sized lnbs side by side would only get sats at 4 deg apart minimum.
Thanks

 

[Mr Tony]

correct

Even the itty bitty Geosat pro LNB's that SatAv sells are for 4 degree spacing

You could get some stacked LNB's...they can do 2 degree spacing due to the way they are built...see here
http://www.satelliteguys.us/1023942-post45.html

 

[Anole]

Can't you buy a few 119/121 lnbs from dish ..
you should just need to change out one of them for a non-dbs lnb..

Second picture, all the way to the right. That's the 121/119 assembly.
The horn and LNB on the right in that picture, is DBS (circular).
The right lnb needs to be changed out for FSS (linear).

Don't have that assembly to measure the spacing between them, or we could calculate if they'd be proper for your location and choice of birds.
The specs of the dish have a bearing on LNB spacing, too!
So, focal length is necessary to do any math.
But at least there's a picture of the hardware in question.

 

[Tron]

I obtained one of those Superdish 121 LNB assemblies last week. The feedhorn(s) are designed for the Superdish, so I don't know how well they would do on another size or type of dish. Unfortunately, the Superdish is somewhat undersized, especially for the harder to get transponders. Also, I'm not sure all receivers play well with stacked LNBs. Of course, one could always replace the LNBs with regular ones, they're standard C-120-flanged models.

 

[sharpee]

Interesting options! Pictures are really cool.
Thats what I like about this hobby. There are so many things that can be done.

 

[jerryt]

Second picture, all the way to the right. That's the 121/119 assembly.
The horn and LNB on the right in that picture, is DBS (circular).
The right lnb needs to be changed out for FSS (linear).

Don't have that assembly to measure the spacing between them, or we could calculate if they'd be proper for your location and choice of birds.
The specs of the dish have a bearing on LNB spacing, too!
So, focal length is necessary to do any math.
But at least there's a picture of the hardware in question.

The 119/121 superdish LNB's are of coarse 2 degrees apart, but that depends on the size of the dish (FD). The feed horns are one inch on center. On a one meter dish the LNB's will be one degree apart.

The 119/121 SD LNB's are not suitable for converting to two FSS (linear) satellites, because the 119 feed horn is designed for DBS satellites. The 119 feed horn has two flats at 1:30 and 7:30, and these flats would not allow FSS LNB's to work.

 

[Anole]

Another factor in LNB spacing, is how close the two satellites are to -your- horizon.
For a given satellite spacing . . .
If the two are near your True South, the LNBs need much more spacing than if the sats are low on the horizon.

As for the 119/121 LNB horn assembly, each has a different sized horn.
It had crossed my mind to run a band saw between the two pipes.
Not sure if there's enough meat to do that or not.
Then, you could use two of the 121 horns and pipes side by side, spaced as necessary.

I suspect... that the 119 horn and pipe is set up for circular and would need reaming to do linear, even if a FSS (linear) LNB could be mounted to it.
So, I wasn't betting the farm on that 119 hardware.

 

[jerryt]

It had crossed my mind to run a band saw between the two pipes.
Not sure if there's enough meat to do that or not.
Then, you could use two of the 121 horns and pipes side by side, spaced as necessary.

There is enough meat, you linked my pictures in this thread of the 121 halves I built (installed). Attached is a picture just before install.