Multiple LNBF on BUD

[equant]

A few weeks ago I decided to try and add a Ku Band LNBF to my C Band bud. I climbed up on a ladder, and tried to find a signal that was 2 degrees west, and then east... Then 4 degrees, but never got a beep from my receiver.

Is this fool-hardy? Can anyone give me any tips? I have a fixed Cband dish, and would love to get Ku from satellites on either side of the prime focus.

Thanks.

 

[truckracer]

I have seen it done where people would drill their scalar ring and affix a ku lnbf. I don't think it works very well being "off axis" on a prime focus dish. I would think you should get something. It may be that if your next to your scalar ring, you are more than 4 degrees off.

I would mount it someway and then bump your dish east and west and see if you lock any ku signals from neighboring sats.

 

[pendragon]

Prime-focus dishes should do better than FTA offset dishes when going after off-axis signals. At 4 degrees off-axis you should only be down around 0.5 dB on gain. There could be several factors to consider:

1. What is the focal length of the dish? This will determine where 2 or 4 degrees off-axis is. It is very likely inside the scalar rings, maybe worse.

2. Some C-band dishes do horrible on Ku. Surface imperfections can make a big difference at higher frequencies.

3. Ku LNBFs are designed for high f/Ds. They will invariably under-illuminate a BUD.

4. I would use a meter for this kind of experiment instead of a receiver.

 

[equant]

4. I would use a meter for this kind of experiment instead of a receiver.

I have a cheapy analog meter; the kind that come in the diy install kits with a crap compass. Would that be worth using?

 

[equant]

I would mount it someway and then bump your dish east and west and see if you lock any ku signals from neighboring sats.

That's an interesting idea, I could bump the dish 1/2 between two sats and then search for a 4 degree sat. If If I find one, that would let me know that a 4 degree sat lies inside the scalar ring.

So if 4 degrees is within the scalar ring area, is it futile to search further out? 6 degrees? 8 degrees? Or am I doomed if I try going that far out.

 

[pendragon]

I have a cheapy analog meter; the kind that come in the diy install kits with a crap compass. Would that be worth using?

That should work just fine.

So if 4 degrees is within the scalar ring area, is it futile to search further out? 6 degrees? 8 degrees? Or am I doomed if I try going that far out.

Measure and post your focal length and we can calculate how far off-center 4 degrees will be. I don't see why you shouldn't be able to find signals well beyond 4 degrees, as long as the other points I raised are accounted for.

 

[ebo]

I have a ku lnbf mounted beside the feedhorn. It is mounted closer than the scalar and about 8 degrees off center. Works fairly well on 7.5' mesh dish. I can pull in RTV at 65 - 70 Q on a coolsat 4000 pro.