10 Ft. BUD and KU FTA

[hecter]

Hello to all testers,
I have a 10 ft. BUD (Prime Focus Dish) and want to mount an Invacom QPH-031 LNB (Linear and Circular).
Does anyone know of an adapter that will let me do this without a lot of modification to the arm?
If someone has done this any suggestions would be appreciated. Also has anyone used the QPH-031 on this big a dish? There are differing opinions on this. Thanks in advance.

 

[Lak7]

Are you going to replace your C Band feed, or looking to strap the QPH to the existing setup?
Here is one that replaces...
C Ku Prime Focus Dishes LNBF Holder

 

[pendragon]

The most critical parameter is the f/D of you BUD. The QPH-031 is designed for offset dishes that have much larger f/Ds than prime focus dishes. If you have a very shallow BUD, it should give acceptable results. However a very deep dish may disappoint you because the Invacom will only 'see' a small part of the dish. Invacom makes Ku LNBs and a feed designed for prime focus antennas.

The other performance consideration is whether the dish is solid, perf or mesh. The latter two can have reduced Ku performance because of surface irregularities, and in rarer cases, holes that are too large.

 

[hecter]

Lak7
I am going to replace the “C” band feed. I am trying to get linear KU and circular KU with one dish and LNB if possible. I already have a motor and controller for the BUD.
Thanks for your help.

 

[hecter]

pendragon
The F/D ratio of the dish is .40. It is a fiberglass dish and is approximately 18 inches deep. The Focal point with the LNB I am using to test with right now measures approx. 48 inches Thanks for your help. Please tell me what you think with this new information.

 

[pendragon]

I've got good news and bad news. The good news is a fiberglass dish should perform well on Ku. The bad news is you're going to lose a fair amount of gain with the f/D mismatch. I'm calculating a loss of about 3.5 dB, which means your 10' dish will be performing like a 6.7' dish for the combination you asked about.

If you want to get the full potential out of your dish with the same functional capability, you'll need to look at something like the Invacom QPF-031 LNB coupled with their ADF-120 feed. However you may not need a ton of gain on the circular Ku, unless you're trying for out-of-footprint reception. Invacom also makes the QDF-031 & QTF-031 that are universal LNBs, linear only.

 

[Lak7]

I am going to replace the “C” band feed. I am trying to get linear KU and circular KU with one dish and LNB if possible. I already have a motor and controller for the BUD.

For best results, I would get a proper Ku Dish with Motor.

 

[pendragon]

For best results, I would get a proper Ku Dish with Motor.

Since OP already has a BUD, motor and controller, getting a prime-focus Ku LNB and feed will likely be a lot less expensive than buying a dedicated Ku dish with the same trimmings. And given the specs, the Ku BUD should be able to dig a lot deeper into the noise.

 

[Lak7]

Since OP already has a BUD, motor and controller.....

I would not sacrifice C Band for only Ku.

 

[tvropro]

I would not sacrifice C Band for only Ku.

Me either, C band is a #1 priority then comes ku.

 

[phlatwound]

Do we even know if that fiberglass dish will even perform on Ku (embedded mesh size)?

 

[hecter]

To all,
I have never tried it on KU. Think what I will do is buy a reasonable KU lnb ( can sell it on ebay if it will not work for me) and try it on Galaxy 18 at 123 degrees and go from there. That will tell me whether to sink any more money into this project or to purchase another dish and setup. Will post back when I find out if the dish will receive Ku band and strength and quality. Thanks to all who have helped out on this.

 

[Anole]

sounds familiar:

Somewhere around here, we had a discussion (or maybe a review) of a Ku LNB suitable for a prime focus dish.
May have been the SL1P GeoSatPro from SatelliteAV, or something similar from Sadoun or WSI.
It performed pretty well in the tests, and isn't so expensive.

If someone remembers or finds the thread, post it here for further discussion.
Might be just what the OP needs.
The Invacom combination would be great for a serious use, but at over $100, it's too expensive to try on a whim.

 

[truckracer]

I would keep the big dish c band and just get a 90cm solid ku dish with a diseqc motor in his situation. you can have your cake and eat it too. Too much on c band to lose in my opinion.

 

[White Cobra]

Hello to all testers,
I have a 10 ft. BUD (Prime Focus Dish) and want to mount an Invacom QPH-031 LNB (Linear and Circular).
Does anyone know of an adapter that will let me do this without a lot of modification to the arm?
If someone has done this any suggestions would be appreciated. Also has anyone used the QPH-031 on this big a dish? There are differing opinions on this. Thanks in advance.

I have a 10' Ku mesh dish and I have only a QPH-031 LNB mounted on it and I love the way it works. I removed the c-band feed horn, the took the plastic case of the Invacom apart(voids warranty), worked 1/2 of case and metal part of LNB and worked through hole in the scalar ring, then worked other part of case through(it will fit, just work slow), snapped case back together. I rapped black tape around neck of Invacom until it was same size as hole in scalar ring. Pulled back on LNB so eye of LNB was against scalar ring and tightened set screw. I would hold but could move by hand so, I cut a piece of hardwood in a circle same size as hole in scalar ring, drilled a hole in middle same size a neck of Invacom, cut piece in 1/2. Installed both " C " shaped pieces, pulled back on LNB so it was all the way against scaler ring then tightened set screw. Worked better! Just make sure LNB is straight up & down while dish is aimed at your true south!!!

Hope this give you a cheaper idea. No need to spend more money just for adapters or new LNBs and adapters!