Quote:
Originally Posted by elgemcdlf
Ok setting focal length. Forget the measurements and setup the dvb receiver and a small tv next to the dish. Now tryint your best not to block the dish slowly move the feedhorn in and out of the scalar ring until you peak signal. That shoudl solve that. I know not very scientific but it works 
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The above is probably OK, and it's pretty much what I do, but there are a couple complications.
First, you have to be dead center on the sat for this to work. If you are on the edge or on a donut shaped spot (which is what the spot tends to look like when the focal length is off), then adjusting to the proper focal length may make the signal worse. Also, moving the throat in and out of the scalar ring is actually changing the illumination of the feedhorn. Really the adjustment should be moving the whole assembly in and out, but on most feeds, there is no easy way to do this.
What I do, is peak the dish on
C-band making sure I'm dead on. There isn't much likelihood that there will be a donut shaped spot on C-band. Then I switch to Ku, and do what you say above. Recently my FL was so far off, that if centered on C-band, I could hardly pickup Ku, and to pick up Ku, I'd have to move the dish to tune on the donut. However after I did the above, now C and Ku show up at the same place, or at least a lot closer, because I didn't finish, because I was chased inside by the bugs.