Xku lnb vs ku lnb

[denada]

What is the difference between xku lnb and ku lnb? Is xku lnb only for smaller dishes or is there xku lnb's for 3.8M dishes? How do you get 4 transponder connections? Is there a lnb for that?

 

[mikekohl]

What is the difference between xku lnb and ku lnb? Is xku lnb only for smaller dishes or is there xku lnb's for 3.8M dishes? How do you get 4 transponder connections? Is there a lnb for that?

Technically both of these LNBFs were used on Shaw Direct Ku band systems. The Shaw Direct device was a customized product that was designed to get the unique frequencies used on Anik G1 at 107.3 West, while also picking up normal Ku-band frequencies from Anik F2 at 111.1 West.

They are called LNBs (terminology has been dumbed down by Shaw Direct, but technically we should know the difference between an LNB and an LNBF. An LNBF combines an LNB for frequency conversion with a Feed device to focus on the signal.) Shaw Direct provided a matched set with four independent outputs to allow use of four separate receivers from both horizontal and vertical polarities of two satellites (Anik G1 and previously Anik F2). Now that Anik G1 will be the only satellite in use, these LNBs or LNBFs only need to receive one satellite (G1).

As originally designed, the XKu device from Shaw Direct was sold in a matched set with either a 60E (60 cm) or 75E (75 cm) antenna. An LNBF for a 60E antenna will not perform properly on a 75E (or any other size) antenna because its focus for two satellites will at best only provide adequate service from one satellite due to the mismatch of focal point distances when the 75E and 60E antenna are compared. An XKu LNBF shipped with a 75E antenna will also be mismatched when attempted to be used on a 60E antenna. I suppose you could now put one of these onto a larger antenna, and tweak it in and out for hottest signal from Anik G1, and optimize the polarity as well as elevation and azimuth. The second satellite function will not matter, so you could experiment.

You need to come to a close match on the f/d ratio of whatever antenna you choose. These are for elliptical offset antennas with a typical f/d ratio between 0.6 and 0.7. If you are trying to use a huge solid prime focus dish (3.8m for example), its f/d will be typically between 0.3 and 0.4. Another mismatch issue because you are trying to do something with an LNBF that does not properly illuminate your dish. If you had a well tuned 2.4m offset Ku-band antenna, you would have much better luck. Resulting signal on a 2.4m offset will almost always be better than a 3.8m prime focus when things are done this way.

There really is not an out of the box solution that works well, because the frequencies found on Anik G1 are outside of the 11.7 to 12.2 GHz used on normal Ku-band reception in North America. Ideally if you had a perfect feedhorn for your large prime focus dish, and a separate LNB did exist to pick up Shaw Direct service from Anik G1, things would be different. But we do not have those options. You've got to make the best use of the stock Xku LNBF from Shaw Direct, have a spectrum analyzer to see exactly what you are doing, preferably attempting this with a large Offset Ku-band antenna of solid construction. Very few people are available in the U.S. that might have the knowledge or test equipment to pull this out of a hat. It needs to be approached scientifically step by step, so you are not wasting time going down rabbit holes, and have previous experience from similar signal finding to get it all right without billing lots of hours in an attempt to get it right. I wish you luck!