One Dish, Same Satellite, Two LNBs

[Jake_E]

This is my first post (not counting the Introduction), and most of the questions I have regarding setting up an FTA system have been answered. I have quite a few, but the biggest one for the moment is whether it is possible to set up two LNBs on one dish that will pick up the same satellite.

The reason I ask is that I would like to get linear & circular polarization Ku feeds, easy enough to do with the QPH-031. But since I'm going with a (motorized) 120cm dish, I'd like to mess around with C band as well.

So in order for me to get Ku band linear & circular AND C band, no matter what combination of LNBs I use, I still need to use two LNBs (either QPH-031 and C band, or a C/Ku LNB and a circular Ku). Ideally I would like it so that both LNBs are receiving from the same satellite.

Any ideas?

 

[Mr Tony]

I would do a C/KU in one and add a DBS offset. Since DBS is much stronger, there is more room for error. Yes it will be off by 5 degrees or so (so if you are aimed at 89 the DBS LNB will be at 94) but the C/KU in one might be the best bet

 

[Jake_E]

I would do a C/KU in one and add a DBS offset. Since DBS is much stronger, there is more room for error. Yes it will be off by 5 degrees or so (so if you are aimed at 89 the DBS LNB will be at 94) but the C/KU in one might be the best bet

That's pretty much what I thought the answer would be, but I was hoping for a different one (i.e. and obscure C/Ku linear & circular LNB that I hadn't found yet, or a way to split one beam to two LNBs, but that would require much greater knowledge of satellite tech than I possess).

Would it be better to mount the second LNB off to the side (making it 5 deg E-W)? Or above (5 deg N-S)?

If it makes a difference, I'm at 79 deg W, 35 deg N.

 

[Anole]

The motor only moves your aim along the arc.
So, if you put an LNB to look 5º up, it wouldn't be looking at the arc at all.

Plus, if you use one of the C/Ku LNBs, I don't think you can get a standard circular LNB close enough to the throat to make the 5º on the side.
Kinda depends on the dish, focal length, and the scaler on the C-band LNB.
There are some pencil-necked LNBs (no pun intended) that might be mounted through the C-band scalar to get closer to the center, but that's out of my league.

Personally, I subscribe to circular service, so swinging a circular LNB around isn't very interesting to me.

 

[Jake_E]

Well, after looking at the BSC 621-2 C/Ku-band LNBF, it says in the installation guide that it can also receive circular signals as well by taking off the end cap and inserting the dielectric material between the throat guides.

Now, is that only for C band, or both C & Ku? (the picture it shows looks like the C band portion. With it in, will you only be able to receive circular, or will it receive circular and linear at the same time?

The other thing I noticed when looking at the manual is that it appears to be a C-band front with a Ku-band LNB bolted to the back end, with the Ku-band LNBF having a separate feed (straight out the back) going into a switch on the C-band portion (the front). So if I can figure out a way to remove the Ku-band portion on the rear and attach the QPH-031 instead, It may just work....

Off to do more research.

 

[Tron]

Now, is that only for C band, or both C & Ku? (the picture it shows looks like the C band portion. With it in, will you only be able to receive circular, or will it receive circular and linear at the same time?

I believe this refers only to the C band portion. "Ku" band circular would actually be DBS, which is at a different, slightly higher and overlapped frequency range.