Is arc too high or too low?

[GrendelT]

About a month ago I bought a generic SG6000 motor on eBay. (mistake) I've had to stop using USALS and just use DiSEqC positions because the positions just aren't right. It seemed to work ok at first, but has degraded in just a few weeks.

Even after manually locating some satellites, I've had to reposition everything after a few days. (I came home last Friday to my motor turned full East for no reason whatsoever - it was not a windy day and nobody had been using it.)

Today I ordered an authentic Stab HH90 motor to (hopefully) correct my issues. It's been pretty frustrating but aside from these issues, the wife and I have been happy with the few channels we get on Ku.
I'm located at 94.7W and able to receive from 83W to 101W, past that to the west I don't get any signal.

One question that's been lingering: How do you know if your motor's arc is shooting too high or too low?

 

[turbosat]

I would say start with the first satellite that has channels that are degrading/weak. Take the tv out to the dish where you can get 'instant feedback'. On a weak channel, push down on the bottom of the dish, see if that helps or hurts, then pull up slightly on the bottom of the dish to check any effect. That should tell you which is the problem.
Firstly though, check the pole for plumb, and make sure the motor bracket is level on the pole. SO many things can upset the tracking of a dish. And for the moving dish motor-I can sympathize. I have one receiver that will start moving the dish on its own if I happen to hit a vacant channel on a satellite. And it will TELL ME, lol, the Motor Moving screen comes up and nothing I can do will stop it, short of rebooting the box! if yours is doing that, it may be the reciever rather than the motor.

 

[Tron]

This diagram may help:

 

[RPB]

If both *ends* are off, rather than azimuth/needing to go east or west a bit

See Tron's post above re: Declination angle

When you changed motors from the SG6000 to the HH90, you probably needed to change the bracket on the back of the dish itself (Mine is different for the HH90and the DG380B using the same dish)

Apparent reason is the motor arm angle

Your elevation/Latitude remains same of course... on motor
Bracket on back of dish changes, it takes into account the declination angle math affected by the motor's arm angle.

Here's my experience with the HH90 (the DG380 used a different *formula* than the HH90 did below) And, the HH90 Instruction booklet *formula* is ...later in the book than it should be

You old-timers/experienced guys will get a laugh out of me wasting a day but ...

What would be nice is if
The manual for the HH90 had had in the directions for setting up *dish* elevation when setting up USALs which they omitted, but included in the section for setting up DiSEqC1.2

The motor was easy, I found my Latitude, made sure post was level/plumb, made sure motor bracket and motor were level ...nothing to it.

BUT dish elevation bracket ...

In USALS section (and many online videos and explanations) it says (after motor Latitude step)(referring to on back of dish, not the motor, obviously latitude doesn't change)
"Align the dish elevation and tighten fixing screws.

(no explanation how to get what the dish elevation angle needs to be)


ok, so I went to Dishpointer, my Longitude is 98, I think "true South/True South Satellite is highest in the arc ...so I find Satellites at 97W and 99W, my elevation for both of those is 54.1 so I set elevation on back of dish to 54.1 WRONG

DiSEqC1.2 section of same instruction book ... same step (after motor Latitude step)

"How to find the elevation value of the dish"
"With the same latitude angle, calculate the elevation angle of the dish according to the formula (the "45 number" in the formula below varies by motor model/brand and has to do with the bend angle in the motor's arm)

Dish elevation to highest point of arc sat if it was a stationary dish
54.1 in my case
minus
(45 minus your latitude) (my lat is 30.76)

so
54.1-(45-30.76)=x
54.1- 14.24=x
x=39.86

so my dish elevation should have been 39.86 instead of 54.1

Seemed like I should have just been able to take an inclineometer to 54 degrees on the face of the dish, and that formula needed checking hard to believe they'd leave it out in the first instructions

SO I went back to Dishpointer, and saw ....
"All Satellites | Motorized Systems | Multi-LNB Setups:"
and I thought ... hmmm cool
so I had my address in there already and had dragged to the spot in my yard where the dish is and
dropped down and picked the motor I have HH90
and

it said
Dish Setup Data
Motor Latitude: 30.8°
Declination Angle: 5.1°
Dish Elevation: 40°
Azimuth (true): 180.0°
Azimuth (magn.): 175.3°

So 40 is close to x=39.86 (dish elevation I took 20 hours finding out how to calculate
and 30.8 for my latitude on the motor is already set

11:00 pm I go lower the dish elevation from 54 to 40 and do a usals scan and there's a bunch of stuff on satellites
I need to correct the left-right azimuth a bit due to my brand new compass dial from the satellite finder kit melted in the heat.

If they had had the formula they had in the DiSEqC1.2 section back in the USALS section ... (or better instructions to go to dishpointer, look for motorized instead of looking up your true south satellite, and select which motor you have) I'd have saved a day... and a melted compass


I would have never found the formula under DiSEqC1.2 for elevation, since I was using USALs I didn't feel I needed to read the DiSEqC1.2 directioss .... except for this sentence in this post

HH Motor Install, Frustration and Recommendations?
SatelliteAV
http://www.satelliteguys.us/threads...commendations?highlight=microhd+usals+gave+up


LOL I read the directions for DiSEqC1.2 and there was the formula for elevation (matched Dishpointer motorized ...)
so I installed using USALS and the formula they didn't tell me in the USALS directions ...

From now on, if it's a motor listed on Dishpointer, "All Satellites | Motorized Systems | Multi-LNB Setups:"
I'll just use Dishpointer's numbers, it's easier than an instruction book and re-learning maths formulas

 

[johann12]

I was going to get the Stab 90, but the US supplier was out and is not going to restock it and I did not want to deal with customs etc., so i bought a SG9120B.

I basically ran into the same problems with a SG 9120B, which is not on the list with dishpointer.
I am at 35.7836 latitude. -81.3378 longitude.
Here are the instructions that came with the motor.
1. traditional installation.
Mount dish to motor, rotate motor with dish to true south or use magnetic south.
Adjust motor angle via inclinometer or elevation/latitude scale on both sides of motor bracket.
Find declination by attached angle table.
Set the antenna dish angle=90 degrees - your site latitude - declination angle. 90 -35.78 -5.7 =48.52
This is wrong and according to this calculation they wanted me to set the dish at 48.52 degrees.
This would had been right if they would had said to use an Inclinometer on the dish to adjust the dish angle with respect of the offset angle.The way it is written most users would use the scale on the dish and that will cause problems.
The 48.52 degrees would had been correct for an stationary dish without an motor pointed at true south.

Then they proceeded with an
2.Quick installation using a receiver with go to x.
Set elevation angle of motor according to your laditude.
Mount dish on motor
Find declination angle by attached table.
Set declination angle by the scale on dish. The reading on the dish scale should be: 40 degreese - delination angle. 40 - 5.7 = 34.7 degreese

So the 34.7 degrees should be correct and that needs to be set on the dish if I am correct.

I sure wish that companies would not copy bad or wrong instructions from each other.

 

[SatelliteAV]

The 9120 manual is a misprint. Unfortunately, this misinformation has been shipped with every 9120 motor for the past few years. You are not the first and likely not to be the last to be misled by this error in the installation manual. If I was the distributor of this motor, I would include a bright neon color paper with the amended correct information...

The correct calculation for the dish elevation angle setting on a 9120b is: 30 degrees minus the declination angle provided by the table found in the 9012 installation manual .

In your case, the motor latitude scale to match your install location latitude (not the elevation scale).

The dish elevation scale will be approximately set to 30 degrees - the declination angle.

 

[johann12]

The 9120 manual is a misprint. Unfortunately, this misinformation has been shipped with every 9120 motor for the past few years. You are not the first and likely not to be the last to be misled by this error in the installation manual. If I was the distributor of this motor, I would include a bright neon color paper with the amended correct information...

The correct calculation for the dish elevation angle setting on a 9120b is: 30 degrees minus the declination angle provided by the table found in the 9012 installation manual .

In your case, the motor latitude scale to match your install location latitude (not the elevation scale).

The dish elevation scale will be approximately set to 30 degrees - the declination angle.

Thank you very very very much for the information.
This will save a lot of frustration and adjustment trials.