OTHER Trouble Aiming 1.2m Dish with Amiko DM 3800 Motor (1 Viewer)

TheBUDGuy

Thread Starter
SatelliteGuys Guru
Jun 17, 2015
140
38
Lexington, KY
For nearly 7 hours today, I tried to aim my GEOSATpro 1.2m dish with an Amiko DM 3800 motor, and got absolutely nowhere. I believe my declination angle is completely wrong, but I don't know how to calculate it. The manual for the motor says "35º-DECLINATION ANGLE," which for my location would be 5.9. My Latitude is 37N and my Longitude is 83W. The motor is adjustable for longitude, so I set it to 37. Here is what the elevation and declination angle table in the manual shows:

Your Site Latitude: 37
Elevation Angle: 53
Declination Angle: 5.9
Dish Bracket Angle: 29.1

Is the declination angle set using the elevation mount on the dish? For example, if my declination angle was 30º, would I set the elevation on the dish to 30º? I've also heard that to calculate the declination angle, you subtract the declination angle from the elevation angle, which would give me 47.1. I've had three different declination angle calculations: 29º, 32º, and 47.1º. All seem to be wrong. I also believe I'm not aiming south. The southernmost satellite for me is at 82W, but there's nothing really there for me to scan, as well as with 81W. I have been unsuccessful all day in aiming the dish with the motor. I partially blame my phone's compass, because when I try to peak at 180º S (due south,) it sometimes will not show 180º in the same spot as last time, maybe an inch off or so. At around 8pm ET, I just moved the dish back to 125W and called it a night. I cannot seem to receive any other satellite at all. I felt like I swept the entire sky to look for 87W and 103W and couldn't pick up a thing. On the MicroHD, I can usually tell if I'm close to locking to a signal because the Q level will bounce to 10%, but the whole time, it was at 0% and I would occasionally see a blip at 7%, but that was all.

What is the elevation angle? Is that the angle I set the dish at? How does declination factor in? And what about the dish bracket angle, how does that factor in to all of this? Forgive the many questions, but this is the first time I've messed around with a DiSEqC/USALS motor and I have no clue what I'm doing. It's frustrating, to say the least.
 

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Have you read through this:
 

TheBUDGuy

Thread Starter
SatelliteGuys Guru
Jun 17, 2015
140
38
Lexington, KY
I actually didn't see that. I'll give it a read. I know I'm doing something worng, most likely my declination angle is off.

Is it even possible to aim/tune with Nimiq 4 at 82W? Lyngsat shows nothing but transponders for Bell TV. I assume I could pick them up, but I'm not entirely sure. All of the transponders are encoded with 8PSK Turbo; I assume I'll still be able to see the Q on all of them, right?
 
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a33

SatelliteGuys Pro
Feb 4, 2015
517
332
netherlands europe
I believe my declination angle is completely wrong, but I don't know how to calculate it. The manual for the motor says "35º-DECLINATION ANGLE," which for my location would be 5.9. My Latitude is 37N and my Longitude is 83W. The motor is adjustable for longitude, so I set it to 37. Here is what the elevation and declination angle table in the manual shows:

Your Site Latitude: 37
Elevation Angle: 53
Declination Angle: 5.9
Dish Bracket Angle: 29.1

Is the declination angle set using the elevation mount on the dish? For example, if my declination angle was 30º, would I set the elevation on the dish to 30º? I've also heard that to calculate the declination angle, you subtract the declination angle from the elevation angle, which would give me 47.1. I've had three different declination angle calculations: 29º, 32º, and 47.1º. All seem to be wrong.

"Motor elevation angle" value, as you can see, is 90 - latitude value.

I'd use the modified motor elevation angle, BTW, so for LAT=37.0 that would be about 52.4 degrees (so that modified latitude would be about 37.6 degrees).
This determines the angle of the rotating axis of the motor.

The dish must be set at an angle against the (bended) motor shaft; that's where the declination offset angle comes in. You found the value 5.9 degrees; but when you use the modified angles you should use about 5.3 degrees.
When you set that angle using the dish's elevation scale, you set the scale at 35 (= shaft bend angle) - 5.3 = 29.7 degrees.

When you would set the dish angle with an inclinometer at the dish face against the horizontal, the signal comes from elevation angle: 52.4 - 5.3 = 47.1 degrees. That is the 'total elevation angle due south' value, that you also found. This is the value for a prime focus dish; for an offset dish you have to account for the offset angle as an extra correction.

These angles must be set while motor and dish are exactly in one line.

After that, the next step is the satellite finding and true south finding. Easiest done while using USALS.

Does this help, to clarify all the numbers you found?

greetz,
A33
 

arlo

SatelliteGuys Pro
Dec 4, 2016
445
192
North Eastern
These may help. I see many times here problems getting mounts setup. Polar mounts and USALS motors are usually pretty easy once you grab the concept of how they are supposed to track. Getting all of your angles dialed in and finding the first satellite closest to 'straight up' in the sky is the first step. After that tweaking it all in is straight forward. I like the idea of using worm gear clamps (hose clamps) on the crank angle arm to keep your dish from moving towards the ground when you move it.
The motor has to be at the 0 reference index and dish has to point straight up in the sky at that point.
Not straight up above you but swinging it left and right so it points as high as it will go. Use a mark on the arm for reference.
Your compass will not get you pointed at the north star, so make sure you use the correct true north figures from charts.


Above.png
Below.png
East.png
Latitude.png
polardish.jpg

Mind you I think this was done by Aussies, so above the equator North Azimuth will actually point the other way.
 

TheBUDGuy

Thread Starter
SatelliteGuys Guru
Jun 17, 2015
140
38
Lexington, KY
Yes, it did. I've been having a hard time recently trying to set it up, now I think I believe I know what I'm doing wrong. Thanks!
 

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