Help with Dish Elevation w/ Stab

[gcgst1]

I have a FC90U mounted on the roof with a Stab HH-100. I'm having trouble getting it to track properly.

My mast is plumb, and my motor is adjusted right on the scale at 36 degrees (my latitude). The dish is mounted to the motor in line with the reference, as best as I can eyeball it.

According to the calculator, my P = 48.1 for AMC-5 (my southern-most bird), which means my elevation should be 48.1 - (60 - 36.1) = 24.2. The scale is very rough on the FC90U, but I put it as close to 24 as I could (the scale is only every 5 degrees, and there is much slop in the adjustment).

My question is, is there a way to determine what the angle should be if I were to stick a universal protractor on the dish itself to get a more accurate measurement?

Using the calulator if I had no motor, the dish elevation is equal to P, 48.1, but that is the elevation of the bird, not the angle of the reflector, correct? If the dish was parabolic, the two would be the same, but these are eliptical, and I don't remember the math to figure it out (getting old).

Any help would be appreciated.

[ZeroBeat]

Hi gcgst1,
Sorry I can't really answer your question. I do not have a technical backround. Sounds interesting though.
What are your settings (eg dish elevation) with AMC-5 peaked, quality wise?
My latitude is 36.4N. Mine are:
dish elevation "18" instead of the calculated value of "24" and the motor "37" instead of "36". I am getting everything. I don't know what the elevation number is, I assumed it's just an empirical guide.

[Anonymous]

Hi gcgst1

The scale on my FC90U was off by 8 degrees. Here is my method.
The motor elevation must be at the lattitude of your location. Then -->
calculate the angle for the face of the dish.
Using Sadoun dish caculator find your look angle for the southern satellite.
Satellite look elevation minus the dish offset equals the angle the dish face
should be at. Example: 45 - 26.4 = 20.4

I put the angle finder dead center of the bolt pattern to set dish face.
Also because the hardware of the dish is so sloppy, you need to start
the elevation adjustment high set some tension on the bolts then pull
down on the dish untill you hit your target elevation. Lock the bolts tight.
This works every time for me!
If you are using the mounting pole that came with the dish kit.
Be careful, its easy to collapse the tube because of the large u-bolts on
the motor. I had to replace my mounting pole.

[gcgst1]

Thanks lintond. This is what I was looking for.

For "dish offset" in your calculation, do you mean the number calculated for dish elevation using the Stab formula?

Look elevation - (60 - Lat) ?

Ex. 48.1 - (60 - 36.1) = 24.2

[gcgst1]

Nevermind, I found the offset is a constant 24.62 for the FC90U. Sorry, brain cramp. Let me try it out.

With this calculation I was off about 7 degrees also.

[gcgst1]

Finally! Tracking the belt o.k. now. I need to tweak it a little. Getting 89-91 quality on the AMC[356] birds, but only 40 on T5 and G10R. I think I'm off a little still. What is a good number for G10R for somone on the east coast (79.9W)?

Thanks for your help.

[Anonymous]

The next step is to check mechanical alignment. You want to verify that
the dish tracking arc matches the arc of the satellites. Pick two satellites
one at 30 to 40 degrees east of your zero reference satellite and one at
30 to 40 degrees west. You should see quality bar readings between
60% and 80% at both locations, all though you may have to hunt
thru the active transponders. If the two locations are not close to each
other signal wise you will have to do some mechanical adjustment.