Confusion on where the focal point is.. Help a girl out..

[AmyGrendel]

Ok I have read countless postings over the years on where the focal point should be
in relation to the feed horn. Now I have a BUD.. Im confused on just where I should
set the scalar/LNB. I have seen that the focal point should be about 1/4 inch inside
the throat. I have also found that it should be 1/4 inch inside the face of the scalar
rings. Which one is it? Here are two pics to explain what I mean.. Is it A or B?

Thanks guys.. Amy.

 

[T4Runner]

The correct answer is "yes". )

Or A

If you have gone through the calculations to determine the focal length, it should be measured to 1/4" inside the throat of the LNBF, but... That,s a starting point.

 

[Lone Cloud]

Even if you have the manual, some of those old dishes still needed tweaking.

The only real way to do it is trial and error. The scalar itself should be pretty much determined by the struts that support it. Putting the lnb one quarter inch in, with its vertical probe in line with the polar mount axle is the right place to start.

 

[truckracer]

it will still need tweaked. On Big Dishes, when installing there is no "set it and forget it" formula. it always seems that i can squeeze more signal out of it by tweaking.

 

[Lone Cloud]

When I was running a BSC 621 on my Birdview, I hooked up a half inch plastic pipe which attached to the inside of the BSC and extended out the hole in the center of the dish.

With my trusty wireless headphones and my receiver set to "beep", I was able to get it pretty well peaked. I slowly moved the lnb in and out and turned it very gently on a few different satellites until I got the best "beep". I put a very small c clamp in the hole, and when I got the best position, I wired the plastic pole tightly to it. Then I motored the dish so I could get access to the scalar, where I tightened the lnb in with the set screw. Then I disconnected the plastic pipe, clamp and wire.

For me, this was easier than a complete trial and error, tweak it and try it process.