Thread: Setting HH motor Latitude

Here is the myth: Once you set the motor lattitude, don't ever change it.

Here is the reason why this is a myth: You have to set it correctly the first time!

How do you overcome this so that you set it correctly the first time?

First of all, you need to understand that the motor elevation the motor latitude angles add up to 90 degrees. Ok, that is simple.

Now, you have to know that your motor latitude must be set to the same degree as your site latitude coordinate. If you live at 87.4 W longitude / 42.5 N latitude, then you must set your motor latitude to 42.5 degrees.

Now, why is this a problem for so many people? It is because of two items...

1] The mast or post that the motor is attached / mounted to is not plumb. This screws all angles period! You simply cannot start with this condition. Reset the mast properly to correct this problem.

2] The angle markers on the motor bracket are not refined or precise enough to determine if you are truly set at 42.5 degrees latitude. You may be at 42.3 or 42.6 or 42.7 degrees. How will you judge this accurately so that you know you are right on the mark?

Ok, what needs to be done in the case of item #2 is to remove the dish and motor tube from the motor. Then, slap a inclinometer (a good quality one) on the belly of the motor and read out the degree shown. This is going to be the motor ELEVATION! Now, remember that I said that elevation + latitude = 90 degrees. You want to set the motor LATITUDE to your site's LATITUDE.

However, the inclinometer is reading motor ELEVATION. Therefore, you must subract that from 90 degrees to know the latitude angle that you are setting the motor to.

In this scenario or example, we want the motor latitude to be 42.5 degrees. So, set the motor ELEVATION as read from the inclinometer to read 47.5 degrees and you will then be correct. 90 - 42.5 = 47.5.

Now, when you have this latitude angle set, you will know that it is correct and NOW you do not move it (ever).

The biggest problem with this is that it is hard to judge if you are attaching the inclinometer on the motor belly properly to get an accurate reading. You cannot really do this with the dish reflector attached nor with the motor tube attached. This is a preliminary step that must be done prior to attaching those components.

The inclinometer must set fully flush and parallel to the flat bottom of the motor housing. Motors may vary in style and make this more difficult if they have raised areas on the belly of the motor. Keep this in mind and apply the inclinometer as needed to read the accurate motor elevation. The seam along the side of the motor where the upper and lower shells of the motor housing meet is an excellent leveling marker, if you can figure out how to utilize it.

A highly accurate inclinometer will allow you to get the motor latitude set correctly if you do it right.

Once this is accomplished, then DO NOT CHANGE IT EVER.

The motor latitude and the plumb of the mast are two of the constants that you must adhere to. If you get these two items set correctly, then you only need to set the dish elevation and the motor azimuth variables to dial in a satellite signal.

The dish elevation and the motor azimuth are the only two angles that you should adjust to peak on a signal. You might need to dabble slightly with the LNBF polarization and focal point (distance from the dish). Adjusting the LNBF is the last step as it would provide the very finest tuning portion of the setup.

The LNBF polarization should be set to ZERO degrees on a motorized system and the focal distance I would personally set to the middle of the range and adjust it later for best signal reception. You souldn't have to worry much about the focal distance unless you are trying to pull in a very weak signal for your location. 90%+ of the time, it is just right.

This isn't too difficult, but you have to have a mental picture of what the signals / angles are doing in order for it all to make sense. If you are adept at framing a house, or a roof and trusses, you will understand angles in this way just fine. Geometry is your frend!

RADAR

Radar, Well lets just say I got mine lined up this spring and I'll never touch it again! I hope. I'd have to say for a newbie last fall, getting my SG2100 set correctly was harder than I thought. I really do need to move it a little farther west down the fence line so I can get 74W and 72W. i've got fixed dishes on those sats now. Maybe a spring project. It is a must to have the pole plumb and solid thats for sure. I finally learned if it's working leave it alone lol. Blind

Originally Posted by Blindowl1234

Radar, Well lets just say I got mine lined up this spring and I'll never touch it again! I hope. I'd have to say for a newbie last fall, getting my SG2100 set correctly was harder than I thought. I really do need to move it a little farther west down the fence line so I can get 74W and 72W. i've got fixed dishes on those sats now. Maybe a spring project. It is a must to have the pole plumb and solid thats for sure. I finally learned if it's working leave it alone lol. Blind

I hear you, BlindOwl!

Setting up a fixed point dish can be tough for a person who is just starting out, and then setting up a motorized dish is just 30 times more difficult! I say 30 times as I am able to to pull in at least that many Ku band satellites with my motor now, so I need my dish and motor properly aligned to do this.

What I wish to convey to all FTA enthusiasts and hobbyists is that when a person gets the basics resolved, the rest truly becomes child's play. Sincerely, if you have the mast installed and leveled, the motor out of the box and attached to the mast, the dish attached to the motor stem (tube) and the portable TV and receiver right there with you, it should take 5 - 10 minutes for you to align and track the entire arc, barring one or two oddball sats.

Walrus and I have been setting up FTA dishes for quite a while now. At first, it wasn't this easy. But, now it is really simple and quick.

What takes the most time is the preperations...

1] Select the band and satellites that you are going to receive.

2] Select the dish, LNBF, switches, receiver, motor and mast hardware that
you are going to use for the installation.

3] Install the mast and level it and wait for the concrete to set.

4] Determine your true south satellite.

5] Determine your angles.

6] Set your angles in roughly.

7] Find a signal from your due south satellite.

8] Peak the signal quality for that sat.

9] Pan east and west and peak the signal quality for all sats.

10] Adjust and tweak as required.

11] Enjoy your creation!

Next time you set in a dish, it will be much faster. Once you have a strategy and timeline outlined, it just breezes along. It will become much more simple than you imagine. Getting the basics down first is key and having a methodical setup approach is necessary - i.e. a step by step set of instructions that you always follow.

Trust me, it becomes so much easire if you plan your entire set up from the start to the finish. Don't just go outside and say that you are going to install a dish today, plan it!

RADAR

Originally Posted by AcWxRadar

Here is the myth: Once you set the motor lattitude, don't ever change it.

I don't agree at all. I set mine, and never changed it until I had to take the motor apart to re-seat the coax connector.

Originally Posted by AcWxRadar

Here is the reason why this is a myth: You have to set it correctly the first time!

How do you overcome this so that you set it correctly the first time?

Well sure, but this is hardly a reason to say it's a myth that you can't set the motor elevation then never touch it again. I think the number one reason that some people get frustrated with aligning a sat dish is that they can't resist the temptation to keep going back and re-adjust the motor elevation. This almost always makes things worse.

Originally Posted by AcWxRadar

First of all, you need to understand that the motor elevation the motor latitude angles add up to 90 degrees. Ok, that is simple.

Now, you have to know that your motor latitude must be set to the same degree as your site latitude coordinate. If you live at 87.4 W longitude / 42.5 N latitude, then you must set your motor latitude to 42.5 degrees.

Now, why is this a problem for so many people? It is because of two items...

1] The mast or post that the motor is attached / mounted to is not plumb. This screws all angles period! You simply cannot start with this condition. Reset the mast properly to correct this problem.

You *CAN* align a dish with a sloping mast, but yes, it makes things MUCH more difficult.

Originally Posted by AcWxRadar

2] The angle markers on the motor bracket are not refined or precise enough to determine if you are truly set at 42.5 degrees latitude. You may be at 42.3 or 42.6 or 42.7 degrees. How will you judge this accurately so that you know you are right on the mark?

Ok, what needs to be done in the case of item #2 is to remove the dish and motor tube from the motor. Then, slap a inclinometer (a good quality one) on the belly of the motor and read out the degree shown. This is going to be the motor ELEVATION! Now, remember that I said that elevation + latitude = 90 degrees. You want to set the motor LATITUDE to your site's LATITUDE.

However, the inclinometer is reading motor ELEVATION. Therefore, you must subract that from 90 degrees to know the latitude angle that you are setting the motor to.

Every inclinometer I've seen will read either in the latitude scale or elevation scale, depending upon which surface of the usually square inclinometer you put against the motor. What I usually do, is put the inclinometer up to the surface you're going to use for your measurement, then tilt the inclinometer down toward the southern horizon. if the readings go down, then you're measuring elevation. If the readings go up, then you're measuring latitude. But yeah, if you only have an inclination indication, such as with a digital level, then yes, you'll need to subtract from 90.

Originally Posted by AcWxRadar

In this scenario or example, we want the motor latitude to be 42.5 degrees. So, set the motor ELEVATION as read from the inclinometer to read 47.5 degrees and you will then be correct. 90 - 42.5 = 47.5.

Now, when you have this latitude angle set, you will know that it is correct and NOW you do not move it (ever).

Now this is where I really disagree. If you've done this, your dish will NEVER be able to track the arc. You cannot track the arc if you have your motor latitude set to your latitude or elevation set to 90 minus latitude. The "*right* angle to set it to is an angle approximately 0.6 more than your latitude (or subtract 0.6 from elevation). I have a calculator that gives a close approximation to the angle you should use at
BJDISCALC2

, however for most purposes the 0.6 adjustment will be OK. As mentioned several times, the reason for this 0.6 is that to see the sats, you also have to set the declination via the dish elevation, and the declination will be more for sats to your south than it is for sats to your east or west by approximately this 0.6 deg amount. The only way to deal with this is to use the declination of an extreme east/west sat, but this will require you to then alter the latitude setting in order to properly track sats to your south.

Originally Posted by AcWxRadar

The biggest problem with this is that it is hard to judge if you are attaching the inclinometer on the motor belly properly to get an accurate reading. You cannot really do this with the dish reflector attached nor with the motor tube attached. This is a preliminary step that must be done prior to attaching those components.

Yeah, this is true. There usually isn't enough room to get most inclinometers in there once you have the dish attached. In some cases you can put a straight edge or a small carpenter's square on the surface to be measured, and put the inclinomer on that, but since you'll never need to touch this again, it's really best to do it before putting the dish on.

Originally Posted by AcWxRadar

The inclinometer must set fully flush and parallel to the flat bottom of the motor housing. Motors may vary in style and make this more difficult if they have raised areas on the belly of the motor. Keep this in mind and apply the inclinometer as needed to read the accurate motor elevation. The seam along the side of the motor where the upper and lower shells of the motor housing meet is an excellent leveling marker, if you can figure out how to utilize it.

A highly accurate inclinometer will allow you to get the motor latitude set correctly if you do it right.

Once this is accomplished, then DO NOT CHANGE IT EVER.

I agree, but why do you call it a myth in your first sentence then proceed to discuss a method that will absolutely require to change the setting or be off by 0.6 deg?

Anyway, we all tend to tell people to set the latitude setting to your latitude, just because it is easier to explain that way, plus for many people, being off by 0.6 deg will be close enough. The problem is, that if someone sets the motor to their latitude, you WILL eventually need to change this. However I really think that if people would start off by using the so called "modified declination", which also requires a "modified latitude" setting, then it is really true that you won't ever have to touch that adjustment again, unless your pole moves or something.

One other thing though. The above applies mainly to small offset dishes, because the motor elevation is more accurately set than the declination, so that setting the motor elevation can be done, then the declination (dish elevation) can be used to fine adjust the alignment. With some prime focus dishes, it is often more accurate to set the declination first, and then never touch THAT again, and do the fine adjustment via the latitude setting. It's just a question of which of the two settings can be done most accurately or most easily.

I havent change the latitude adjustment on my SG2100 since it was installed 5+ years ago.

Originally Posted by B.J.

I don't agree at all. I set mine, and never changed it until I had to take the motor apart to re-seat the coax connector.

Well, now that is obviously a different circumstance altogether.

Originally Posted by B.J.

Well sure, but this is hardly a reason to say it's a myth that you can't set the motor elevation then never touch it again. I think the number one reason that some people get frustrated with aligning a sat dish is that they can't resist the temptation to keep going back and re-adjust the motor elevation. This almost always makes things worse.

This is exactly what I mean to express. Adjusting the motor latitude should not be a temptation while tweaking and fine adjusting the arc. If it is set properly right from the start, it should remain there. I am using the term "myth" rather loosely, but that is in order to make the point.

Originally Posted by B.J.

You *CAN* align a dish with a sloping mast, but yes, it makes things MUCH more difficult.

Oh, yes! This wouldn't be too bad if you were setting up a fixed point dish. You could compensate for this without too much trouble. But, with a motorized dish? Uh uh!

Originally Posted by B.J.

Every inclinometer I've seen will read either in the latitude scale or elevation scale, depending upon which surface of the usually square inclinometer you put against the motor. What I usually do, is put the inclinometer up to the surface you're going to use for your measurement, then tilt the inclinometer down toward the southern horizon. if the readings go down, then you're measuring elevation. If the readings go up, then you're measuring latitude. But yeah, if you only have an inclination indication, such as with a digital level, then yes, you'll need to subtract from 90.

The inclinometers that you can buy from Menards or most any hardware store like I use (if placed against the flat belly of the motor) always read out the angle of the ELEVATION. Since the motor stem extends at a right angle or 90 degrees from this surface, the angle of the motor stem is what needs to be set to the same angle as the latitude. On my SG-2100 and DG-XXX series motors, the belly of the motor is the most true and flat surface to take the elevation reading.

Originally Posted by B.J.

Now this is where I really disagree. If you've done this, your dish will NEVER be able to track the arc. You cannot track the arc if you have your motor latitude set to your latitude or elevation set to 90 minus latitude. The "*right* angle to set it to is an angle approximately 0.6 more than your latitude (or subtract 0.6 from elevation). I have a calculator that gives a close approximation to the angle you should use at
BJDISCALC2

, however for most purposes the 0.6 adjustment will be OK. As mentioned several times, the reason for this 0.6 is that to see the sats, you also have to set the declination via the dish elevation, and the declination will be more for sats to your south than it is for sats to your east or west by approximately this 0.6 deg amount. The only way to deal with this is to use the declination of an extreme east/west sat, but this will require you to then alter the latitude setting in order to properly track sats to your south.

I have considered your notion regarding this compensation of 0.6 degrees. However, I had not utilized this when I first set up my motor and dish as I was unaware of this at the time. I just set the motor to the precise latitude degree of the site and all was well - I did not have to make any compensations when aligning to the arc and I am able to cover an arc of 118 degrees spot on for every satellite. But, I promise to incorporate it during my next dish installation to see how everything works out. If it improves results for me, I will apply this.

Originally Posted by B.J.

Yeah, this is true. There usually isn't enough room to get most inclinometers in there once you have the dish attached. In some cases you can put a straight edge or a small carpenter's square on the surface to be measured, and put the inclinomer on that, but since you'll never need to touch this again, it's really best to do it before putting the dish on.

Exactly.

Originally Posted by B.J.

I agree, but why do you call it a myth in your first sentence then proceed to discuss a method that will absolutely require to change the setting or be off by 0.6 deg?.

Well, I guess I was using the term a bit loosely. It is not a myth, but rather a taboo. As you also have stated, it is that temptation to dabble with this angle setting when a person is not achieving the desired results right off. And, as you say, it just compounds their misery.

Originally Posted by B.J.

Anyway, we all tend to tell people to set the latitude setting to your latitude, just because it is easier to explain that way, plus for many people, being off by 0.6 deg will be close enough. The problem is, that if someone sets the motor to their latitude, you WILL eventually need to change this. However I really think that if people would start off by using the so called "modified declination", which also requires a "modified latitude" setting, then it is really true that you won't ever have to touch that adjustment again, unless your pole moves or something..

You are likely quite correct, but as you also say, that 0.6 degree compensation may not be entirely necessary - it will likely be close enough for most. And, it indeed is easier to explain when you are communicating the way we are - i.e. using the web and a forum where you are not directly speaking face to face with the person you are helping.

Originally Posted by B.J.

One other thing though. The above applies mainly to small offset dishes, because the motor elevation is more accurately set than the declination, so that setting the motor elevation can be done, then the declination (dish elevation) can be used to fine adjust the alignment. With some prime focus dishes, it is often more accurate to set the declination first, and then never touch THAT again, and do the fine adjustment via the latitude setting. It's just a question of which of the two settings can be done most accurately or most easily.

Yes. I was directing the overall scope of the discussion to an offset, smaller Ku band dish and not a prime focus dish.


B.J.

You have really picked my theory and information to the bare bones! However, your arguments seem to help support it (except for your addition of the modified declination) which is something very beneficial to consider here.

The main point I was trying to infer is to get the latitude setting correct right off the bat and then never alter it. Many people were, as you say, getting frustrated and wanting to adjust this later to compensate for some other error that they could not identify. This of course leads to a big mess and more frustrations. It is the WRONG direction for them to go.

When I set up my first motor, I was a bit like that, too. It bothered me that there was so much space in between the degree markings on both the motor bracket and the dish assembly and I thought to myself that this would leave a huge margin for error. So, using a very sensitive and accurate inclinometer and bubble level, I set out to determine a more refined approach (measurement).

In other words, the motor latitude adjustment should not be considered as a variable. Just the same as having the mast plumb. These should both be constants and then you will be left with just barely two variables. The azimuth alignment and the dish elevation. The dish elevation (I have found) is less than a variable, too. If everything else is set correctly, then this too will be so doggone close to what is calculated that it is unreal. But, alas - the angle markings on the dish are vague and leave the exact adjustment angle up to interpretation.

RADAR

Good information, and a good read.

BJ, What about the Stab motor? It does not have a declination setting therefore as per STAB and the motor documentation the Elevation should be set to your exact Latitude (no 0.6 degree difference). The scale on the motor has 0.1 degree tolerance or error margin. I have always set the ones I have installed to the exact Latitude 43.X (I do not travel far , lol)

**** The tolerance is acctually 1 degree, so I can only set it half way between 43 and 44. ****

Originally Posted by hd fan

BJ, What about the Stab motor? It does not have a declination setting therefore as per STAB and the motor documentation the Elevation should be set to your exact Latitude (no 0.6 degree difference). The scale on the motor has 0.1 degree tolerance or error margin. I have always set the ones I have installed to the exact Latitude 43.X (I do not travel far , lol)

Re Stab motor & declination... You don't really set the declination with the motor, you set declination via the dish elevation. However different motors have a different angle of bend in the motor shaft, which is a preset declination MUCH more than you need, that allows you to set a negative declination by adding a positive dish elevation (ie if your declination is 5 degrees, and the bend in the shaft is 30, then you use 25 deg to get 25-30=-5.... if that makes sense.

Re the motor directions telling you to use your latitude, yeah, that's what bothers me, because their manuals are simply wrong. I think they do that just because it's easier, and the 0.6 deg won't make any difference to many people. However what I've seen in forums like this, is that when someone's latitude is say 40.4, they will round off to 40, which puts them even further away, ie a whole degree. Then I see people using these complicated methods of going to the extremes, and seeing if lifting up or pulling down improves or makes it better, then altering the declination, which results in you having to change the latitude adjustment...... or people just see that they can get some improvement when they used the exact latitude, and start changing things randomly, and end up making things worse.
My whole point was, that if you make a good effort to set the latitude adjustment right in the first place, and best if that right is the modified numbers, then I agree with Radar's statement that you set it and never touch it again. For many cases, particularly with smaller dishes, you may not notice any difference due to being off 0.6 deg.