How To: Setting Elevation On Stationary Prime Focus Dish

[AmericanZ28]

Since I had such a hard time finding a clear answer, I thought I'd post instructions on how to set the elevation on a stationary Prime Focus Dish. Unlike the majority of people here, I was trying to set up a stationary dish, and kept getting confused when many of the posts I found kept mentioning Latitude, Southern Most Bird, True South, Declanation, and Total Elevation. If your setting up a stationary dish, FORGET ALL THAT! Assuming you've completed the preliminary steps (i.e. Plumb/Level Mount, unobstructed view of satellite) Do the following;

STEP ONE:

Go Here: Satellite Look Angles Satellite Heading Calculator Azimuth Elevation Skew Tilt LNBF Latitude and Longitude values And type in your information and desired satellite. Write down the DISH SETUP DATA, and head to your stationary dish.

STEP TWO:

Place your inclinometer (zero facing up) on a surface that is parallel with the face of your dish (Rear Support Bracket/Plate, Edge of Dish, Center Face of Dish, Scalar Surface).

STEP THREE:

Elevate dish until inclinometer reading matches that of DISH SETUP DATA for Elevation. THATS IT! You may still have to adjust a little to fine tune your signal, but this will get you in the ballpark.

PICTURE ONE: MY RESULTS FOR SATEMEX 5 ASKED FOR 49° degrees.

PICTURE 2: USING THE FLAT PART OF THE SCALAR, MY INCLINOMETER CONFIRMED MY 49° ELEVATION.

 

[truckracer]

you are doing it right but since thats a polar mount, if you try to turn the dish with the mount you are losing elevation either direction of your zenith (highest position). you will have to make sure your elevation is constantly 49 degrees (if thats correct foryour location). You azimuth heading will have to be very close then try to maintain your elevation.

It may actually be easier to use an actuator, set up the polar mount to be moveable and then just use a car battery or something to position the dish since you won't be moving it much.

just a thought to save you some money and trouble.

 

[Achebee]

Good Post

Thanks for the photos, this is helping me clarify some issues right now.
Good Post!!!

 

[nycrich]

Good article and pics. I have a fixed 6 ft C-band dish. I found out however that you must set the declination angle for your location. It will improve the weaker transponders and might increase the signal on stronger transponders.

 

[B.J.]

Good article and pics. I have a fixed 6 ft C-band dish. I found out however that you must set the declination angle for your location. It will improve the weaker transponders and might increase the signal on stronger transponders.

? If you have a fixed dish, declination is meaningless.
If you measure your elevation as shown in the pictures above, ie on the dish, rather than at the rotation axis, then you don't need to consider declination.
Declination is only an issue if you are using a polar mount to track the arc, in which case, then your declination is important, but in that case, the Az/El values for the sats aren't used.

 

[John Popper]

so how do you get the declination measurement for your location? dish pointer only shows you azimuth and elevation?

 

[Greg Mueller]

so how do you get the declination measurement for your location? dish pointer only shows you azimuth and elevation?

This page is pretty helpful

Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing

use the "modified" angles

 

[Babadem]

so how do you get the declination measurement for your location? dish pointer only shows you azimuth and elevation?

Here is a Tool to determine you local declination.

 

[B.J.]

This page is pretty helpful

Footprints by Dish Size - Latitude Declination Chart - C/Ku-Band Satellite Listing

use the "modified" angles

The 2nd chart on this page is the most accurate, ie the "modified" declination chart.

Here is a Tool to determine you local declination.

Before this gets confused, I should mention that unfortunately there are two terms we use that are called "declination. The main one that is refrered to in the geo-orbit modified chart is the astronomical declination that is the angle you need to aim below the earth's equatorial plane. The 2nd declination that Babadem refers to is magnetic declination, which is an adjustment to convert magnetic headings into true headings. The Azimuth used in the Az/El values for sats needs to be TRUE azimuth, so if you use a magnetic compass you need to adjust for the magnetic declination too. If you use the sun for azimuth, you don't need to make this adjustment.

 

[AmericanZ28]

you are doing it right but since thats a polar mount, if you try to turn the dish with the mount you are losing elevation either direction of your zenith (highest position). you will have to make sure your elevation is constantly 49 degrees (if thats correct foryour location). You azimuth heading will have to be very close then try to maintain your elevation.

It may actually be easier to use an actuator, set up the polar mount to be moveable and then just use a car battery or something to position the dish since you won't be moving it much.

just a thought to save you some money and trouble.

Not necessarily. If you loosen the actual mount on the pole, you can set your azimuth without affecting elevation. Im my case, this is what I'm doing:up!

 

[B.J.]

Originally Posted by truckracer
you are doing it right but since thats a polar mount, if you try to turn the dish with the mount you are losing elevation either direction of your zenith (highest position). you will have to make sure your elevation is constantly 49 degrees (if thats correct foryour location). You azimuth heading will have to be very close then try to maintain your elevation.

It may actually be easier to use an actuator, set up the polar mount to be moveable and then just use a car battery or something to position the dish since you won't be moving it much.

just a thought to save you some money and trouble.

Not necessarily. If you loosen the actual mount on the pole, you can set your azimuth without affecting elevation. Im my case, this is what I'm doing:up!

I think you missed his point. If you align the polar mount, then all you have to do is run the actuator to go from sat to sat. If you loosen the mount on the pole, it becomes a mess, because you have to adjust both the azimuth and elevation differently for each sat. You may be able go go back and forth between 2 or 3 sats without changing the elevation, but that's about it.

What I did, which is similar to truckracer's battery idea, was to take the motor off an actuator, and make a drive piece that would replace the drive piece from the actuator, and put that in a battery powered hand drill. When I wanted to go from sat to sat, I just took my meter and hand drill out to the dish, and would screw it east or screw it west. Worked pretty well until I broke the fitting on the actuator ( the actuator was pretty well frozen up from not being used in years, and I tried to force it).
I've seen posts about using a hand cranked actuator too.

Years ago, I did what truckracer suggested for several months. I used a car battery charger, not the battery. A cheap battery charger will usually put out a voltage that might be in the 18-20 V range. That was back in the analog days, and it was pretty easy to see and recognize the sats as they go by. In today's digital age, it isn't quite as easy to find the sats, but it can be done.

 

[AmericanZ28]

I think you missed his point.

Hmmm I crossed through about 5 sats to try and pickup another and my elevation didn't change from one point to the other. Could it be that maybe I don't have a polar mount? I dont know it you can tell from the picture, but my my mount has 2 open straps that wrap around the pole and squeeze the pole when the straps are tightened. It has an actuator on it, but I removed all hardware associated with it along with the actuator itself. What do you think?

I see what your saying though based on other mounts that Ive seen that have screws that lock the mount againts the pole.

 

[B.J.]

Hmmm I crossed through about 5 sats to try and pickup another and my elevation didn't change from one point to the other. Could it be that maybe I don't have a polar mount? I dont know it you can tell from the picture, but my my mount has 2 open straps that wrap around the pole and squeeze the pole when the straps are tightened. It has an actuator on it, but I removed all hardware associated with it along with the actuator itself. What do you think?

I see what your saying though based on other mounts that Ive seen that have screws that lock the mount againts the pole.

On re-reading the above, I'm not completely sure I understand what you OR truckracer were saying.

The thing is that each sat will have a different elevation, and if you use your mount as an Az/El, then you have to adjust both Azimuth and Elevation to go from one sat to another.
I *THOUGHT* that truckracer was trying to say that since you actually had a polar mount, that it would be easier for you to go from sat to sat, since it only involves one adjustment, ie rotating around the polar axis. However on re-reading, it almost sounds like he's saying the opposite, talking about keeping a constant 49 deg. I'm not sure.

But whatever, what you're doing seems appropriate for using the mount as an Az/El. But as you move from sat to sat, your elevation is staying constant, and each sat has a different elevation, so you'll have to adjust both elevation and azimuth, and actually you'd have to also adjust the polarity skew as well. If you would set up the mount as a polar mount, then you wouldn't have to rotate the whole mount on the pole. All you'd have to do is to rotate around the polar axis.

On the other hand, if, as you mention elsewhere, you can get the azimuth fairly accurately, some people find it easier to find sats with an Az/El arangement, so whatever is easier for you.

BTW, your picture is a good illustration of declination, ie the difference between the polar axis inclination and the actual elevation of the dish itself. However it sure looks like the declination is set at a very high angle. Looks like 10-11 deg, which is too high, but that might be an optical illusion. But if you ever try aligning it as a polar mount, be sure to check out the declination. It's not obvious {to me} how it's adjusted on that mount.