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Originally Posted by elgemcdlf
If your motor is "not landing properly" it actually is landing properly but your adjustment is off.
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This MAY be the case some times, but certainly not always.
Quote:
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Originally Posted by elgemcdlf
Dish elevation sets the shape of the arc and motor elevation sets the position in the sky.
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I keep hearing this description, and I know where it comes from, which is from some diagrams trying to show the "arc" of the Clarke belt going across the sky, then using that to show what adjustments do to cause your aim to describe a different "arc". This description is a good aid toward figuring out what different adjustments do. However this description has always seemed a bit simplistic to me, and doesn't really represent what is actually happening.
What is really happening, is that when your motor turns, if there were no declination, the aim of the dish would describe a perfectly flat plane, above the Clarke belt at all points, provided that it was parallel to that plane. When you introduce declination, the shape described by the dish aim is a CONE,not really an arc since the aim of the dish is down by around 5-7 degrees, ie a real blunt cone. If the dish were at the north pole, and could see through the earth, that cone could intercect the Clarke belt at all points. However the dish is not at the north pole, but is offset from the center of the Clarke belt. That cone can now hit the Clarke belt to the south, but will be a bit off to the east or west, because it is closer to the sat to your south. If you set your declination so that the cone hits at sats to your east or west, then it will be off to your south. So what you do, is to set the declination for the sats to your east and west, then tilt your motor elevation back a bit so that the cone intercects the sat to your south. Ie you are tilting a CONE to make it intercect the Clark belt.
Anyway, this probably confused things even more, but it has always bothered me when people talk about changing the shape of the "arc", when changing the declination is really changing the bluntness or sharpness of the CONE described by the dish aim. There really isn't any "arc" involved here, other than this imaginary picture of how the Clarke belt seems to go across the sky, which is kind of choosing some arbitrary plane that the cone intercects. I just find it easier to understand what the adjustments do by thinking of cones, rather than some arbitrary plane that the cone intercects. Unfortunately, a 3 dimensional cone isn't easy to draw.