LNBF Focus Adjustment

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Thread Starter
Active SatelliteGuys Member
May 26, 2008
I'm getting ready to put my new dish up on the roof. One thing I don't see in all of the instructions I've found on the web for installing a motorized FTA dish is where to mount the LNBF along the feedhorn throat. I have an Invacom QPH031 that is currently mounted with the end of the feedhorn as close to the dish as possible, but it could be moved out away from the dish as much as 5/8 inches. Is there a known focal length setting I should put this at?
After I get the dish mounted, the LNBF will be 25' above the ground, and I don't want to mess with it there.


SatelliteGuys Master
Pub Member / Supporter
Feb 28, 2008
Near Chicago, Illinois
Usually whatever gives you the best signal. I have the same LNB, didn't see any change where it was positioned. Can you test on the ground before mounting on the roof?


SatelliteGuys Pro
Jun 23, 2005
South Florida
installing a motorized FTA dish
After I get the dish mounted, the LNBF will be 25' above the ground, and I don't want to mess with it there.

Either you are very good at setting up a motorized dish on the first attempt or you do not realize that setup takes a lot of access.


SatelliteGuys Pro
Oct 27, 2006
Southern Maine
Is there no where else on your property that will give you a line of sight to the arc? I think most people on this site agree lower is better. Ideally you should be able to reach it comfortably from the ground. I have the same dish and motor but mounted on a pole cemented in the ground.


SatelliteGuys Family
Apr 30, 2008
I second what avg1joe says about being on the ground. Setting isn't as hard as it may seem if you follow the steps exactly. I was able to get mine up and tracking in under two hours(lucky). But on a roof, no tv and STB right there.... well that would had been days of fiddling. I also have the same LNB on my motorized dish and played with sliding it back and forth, no difference seen. I would say just lock it down at zero skew and have fun.


SatelliteGuys Pro
May 1, 2007
If you can get it ground mounted. I had my dish on the roof and it was a big pain to work on, Then the winter winds worked it over so I was messing with this dish on the roof all the time. Once I moved it off the roof it made FTA much more enjoyable. I can walk right up to the system and tweak with no worries of falling off a ladder or roof. If its on the roof and you have some type of health problem pop up that keeps you for getting up on the roof your FTA days are done if the dish gets out of alignment until you can get help and then not everyone has the feel for adjusting it, happened to me. Try your hardest to get the dish on the ground if you can.
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