For the 9 millionth time - setting the elevation....

[drboyddrboyd]

OK, I've searched on this until I'm blue in the face, and that's the problem - I keep coming up with different answers.

The motor is an SG 9120 and the dish is a WS 9036. My latitude is 33.32 degrees north.

OK, I go to dishpointer dot com, and my closest-to-true-south satellite is Anik F2, at an elevation of 51.2 degrees. That's total elevation above horizontal, right? Right.

Just to make double-sure, I check the little-bit-west satellite and the little-bit-east satellite, and they're both 51.2.

So, my total dish elevation to start, pointed due south, should be 51.2 degrees above south horizontal. (This is ignoring the dish offset for now)

Now, my motor shaft (not the tube) should be pointed directly at the North Star. This means my motor shaft should be aimed 33.32 degrees above true north flat horizontal. Right? Right.

So, the dish should start at true south, with the motor shaft pointed north-star north, and the total dish elevation at 51.2 degrees.

The dish offset is 24.62 degrees, which means it's looking 24.62 degrees above where it seems to be looking, right?

So, I subtract 24.62 from 51.2 and the apparent dish angle (like if a laid a straight edge across the face of the dish and took a 90 off that) would be 26.58 degrees above south horizontal..

If I'm wrong about something here, please holler at me!

Thanks!!

 

[Lak7]

OK, I've searched on this until I'm blue in the face, and that's the problem - I keep coming up with different answers.

Do you have the instruction manual?

Double check Pole is Plumb
Set Motor "Latitude" scale to your Lat. (not elevation)
Read motor manual for proper Dish Elevation setting
Setup Receiver, enter proper LNB and Switch Settings, and select a known Hot Transponder for your True South Sat.
Bring Receiver and TV to Dish if possible
Adjust Azimuth

 

[SatelliteAV]

Correct. That dish angle setting should match the dish angle setting specified for your latitude in chart provided in the motor's Owners Manual.

The dish angle setting should be set an angle that is calculated to be 40 degrees minus the declination angle provided in the chart for your latitude.

 

[Keystone7]

Hello drboyddrboyd,

Read your post. I have the same dish and motor as you. I am not the smartest, but my system does work great. When I setup my dish and motor, I had the question of which side of the mounting bracket to the dish do I look at. There were numbers on both sides. Heck, I even had the small mount upside down. After few emails with the company, I was told to use the numbers on the left side as you are standing behind the dish. Those numbers are to be set at your Lat.. My numbers are:

41.36N = Lat. ( on the left side of dish mount at looking at rear of dish)
86.31W =Lon. ( Left to right using compass to get into the ball court)

My south satellite is 87West. That will be my 0 set on my motor. Try and look for your true south satellite.

I could never understand all the offset and subtract talk, quess I'm not that smart. But, hey, my system works great! I also got my information off (dishpointer) and then website (NOAA) where I put in my zipcode and got my lat. and lon. information there also.

When setting your system up, be sure to take small TV and Box to the dish and a good CHAIR to zero in your south satellite. Beleieve me. It will work and when you do get your satellite, it's great. I'm located in northern Indiana.

Don't want to forget to tell you, this site is the best for FTA information.

 

[B.J.]

OK, I've searched on this until I'm blue in the face, and that's the problem - I keep coming up with different answers.

The motor is an SG 9120 and the dish is a WS 9036. My latitude is 33.32 degrees north.

OK, I go to dishpointer dot com, and my closest-to-true-south satellite is Anik F2, at an elevation of 51.2 degrees. That's total elevation above horizontal, right? Right.

That is the elevation of the satellite above the horizon, but it does not correspond to ANY angle setting on your mount, so you shouldn't be using it.

Just to make double-sure, I check the little-bit-west satellite and the little-bit-east satellite, and they're both 51.2.

So, my total dish elevation to start, pointed due south, should be 51.2 degrees above south horizontal. (This is ignoring the dish offset for now)

Again, ignoring the dish elevation, dish offset, declination, etc, NO, there is nothing that you set to 51.2.
I think you're talking about the motor elevation angle here, and as mentioned above, this should be set using you latitude. I would recommend using your latitude PLUS 0.6 deg, ie approximately 34 deg. It is OK to just use your latitude, but you will be off by 0.6 deg if you do it accurately, and if you happen to round off to 33, then you'll be off by a whole degree, so I'd recommend putting your latitude scale on 34 and if your mount has an elevation scale, that should be 56.

Now, my motor shaft (not the tube) should be pointed directly at the North Star. This means my motor shaft should be aimed 33.32 degrees above true north flat horizontal. Right? Right.

Correct, however as above, I'd recommend using 34 degrees instead.

So, the dish should start at true south, with the motor shaft pointed north-star north, and the total dish elevation at 51.2 degrees.

The dish offset is 24.62 degrees, which means it's looking 24.62 degrees above where it seems to be looking, right?

Ignoring the 51.2 part, yes.

So, I subtract 24.62 from 51.2 and the apparent dish angle (like if a laid a straight edge across the face of the dish and took a 90 off that) would be 26.58 degrees above south horizontal..

If I'm wrong about something here, please holler at me!

Thanks!!

This should get you in the ball park, but I've never found those offset angles to be either accurate, or easy to measure or easy to use. I've never found any surface on my dishes, includint the straight edge across the face, which gives useable angles, but it might work for your dish. I think you're better off using the 40 minus declination angle thing on the dish mount that SatAV recommended.... EXCEPT, that instead of the declination listed on the chart, I would recommend using a declination of 4.8 (ie I'm guessing that the charts tell you to use a declination of about 5.4, which will make you 0.6 deg off on extreme satellites). But even this adjustment is still just a starting point, because this setting will be accomplished by peaking on your true south sat, and you'll be changing this anyway.

 

[stanleyjohn]

Hang in there drboyddrboyd!its just a matter of time before you get it right.Take it from me! i am still a rookie at this and if i still had hair on my head it would be gone by now :haha.I found out that its a very fine line between getting a Sig from the satellite and nothing at all.Took me days to find that true south point! then a few nights ago when i turned on the receiver,set my true s satellite (AMC6) and clicked on a strong active Tp!I decided to just move my motor a click at a time west then east from where AMC6 should be and finally got a strong Sig and quality reading.Boy was i happy to see that and at that point turned off the motor so i wouldn't loose the Sig.Once you find your true s satellite! setting the motor to true south became much easier.Since i was working solo on this and had no visual of the receiver TV screen from the Dish set up which is located on my garage roof i had i think of a solution.I ended up buying two 16ft usb extension cables to hook up to a web cam which i used with my laptop to see my tv screen while adjusting the motor/dish to find true south.Before making any movements on the motor i marked off with some masking tape on the mast,motor and dish where all was pointing for my AMC6 satellite!i even took a few pics from ground level of where the dish was pointing If i lost it after adjustments were made i was going to make sure i would find it again.Sorry for the long post but i think i know what your going thru and hope this helps. Stan!!

 

[drboyddrboyd]

OK, the dish angle setting off the motor declination chart is 40 - 5.42 (that's interpolated between 33 and 34). That's 34.58.

The "take your latitude and add .6" gives 33.92.

I've got a Wixey digital angle gauge that's supposed to be good to 1/10 of a degree, but I'm just not understanding why the discrepancy between 33.92 and 34.58.

The more I read the confused-er I get.

Sigh.

 

[AcWxRadar]

Correct. That dish angle setting should match the dish angle setting specified for your latitude in chart provided in the motor's Owners Manual.

The dish angle setting should be set an angle that is calculated to be 40 degrees minus the declination angle provided in the chart for your latitude.

Drboyd,

Brian is correct here and the gist of it all is that the MOTOR MANUAL tells you how to set the angle on the dish. The instructions for the dish antenna itself don't go into this when applying a motor as it is merely for mechanical assembly instructions, not the angular settings.

The motor is the heart of these adjustments and so all the angular settings are referenced from the motor's point of view and thus stated in the instructions for the motor installation.

RADAR

 

[drboyddrboyd]

Well, not to dis WSI, but the motor manual would have to be significantly improved in order to be classified as "lame." It refers to cartoon-quality stampings on the dish frame and the motor frame as being useful for set-up, which they ain't.

Drboyd,

Brian is correct here and the gist of it all is that the MOTOR MANUAL tells you how to set the angle on the dish. The instructions for the dish antenna itself don't go into this when applying a motor as it is merely for mechanical assembly instructions, not the angular settings.

The motor is the heart of these adjustments and so all the angular settings are referenced from the motor's point of view and thus stated in the instructions for the motor installation.

RADAR

 

[AcWxRadar]

OK, the dish angle setting off the motor declination chart is 40 - 5.42 (that's interpolated between 33 and 34). That's 34.58.

The "take your latitude and add .6" gives 33.92.

I've got a Wixey digital angle gauge that's supposed to be good to 1/10 of a degree, but I'm just not understanding why the discrepancy between 33.92 and 34.58.

The more I read the confused-er I get.

Sigh.

Drboyd,

To help explain. Let's do it by the manual first.

Your latitude is 33.32°N.

Set your motor latitude to 33.3°.

The motor manual chart shows your declination to be 5.4° for this latitude.

Subtract 5.4 from 40° (40° is the bend angle of the motor tube for your specific motor).

40 - 5.4 = 34.6°.

Set your dish elevation angle to 34.6°.

I wanted to explain the modified declination angle notion, but I am not sure that I have it correct. I will allow B.J. to state this so that I don't make an error.

RADAR

 

[B.J.]

OK, the dish angle setting off the motor declination chart is 40 - 5.42 (that's interpolated between 33 and 34). That's 34.58.

The "take your latitude and add .6" gives 33.92.

I've got a Wixey digital angle gauge that's supposed to be good to 1/10 of a degree, but I'm just not understanding why the discrepancy between 33.92 and 34.58.

The more I read the confused-er I get.

Sigh.

? 33.92 is the "modified latitude", 34.58 is the dish elevation via the "conventional method" which you get by using a your 5.4 conventional declination from the charts. Two completely different things.

The "conventional" way of aligning dishes, which those charts use, is to align the motor's axis parallel to the earth's axis (ie pointing to the north star). If your dish aims perpindicular to the motor's axis, it will sweep out a plane that is parallel to, and a few thousand miles above the earth's equatorial axis, since you aren't at the equator. To aim at the sats, you have to tilt your dish aim down a bit, while keeping the rotation axis parallel to the earth's axis. This is the declination. Since this declination is a negative number, you can't set that with a dish elevation that's only positive, which is why your motor's axis is bent by 40 degrees, and you have to raise the dish by that 34.58 deg to get the 40-34.58=5.42 declination.
For your 33.3 latitude, you can calculate the declination angle to your south satellite, and it will give you that angle of 5.4 that you see on the charts. Using the elevation of your motor axis, which is 90-33.3=56.7, and subtracting the 5.4 deg declination, the 56.7-5.4=51.3, which except for roundoff error equals the 51.2 elevation of your south satellite.
The PROBLEM, however is that that 5.4 deg declination is ONLY true for your south satellite. Since all the other satellites are further away, the declination gets smaller and smaller, the further east or west you turn your dish. When aimed at an extreme east or west sat, the declination will be approximately 4.8 degrees. So your aim will be off by 0.6 degrees when aimed to the east or west.

TO fix this 0.6 deg error, there is what is referred to as a "modified declination" method. With this method, instead of using the declination of a south sat, you use the 4.8 deg declination of your extreme sats. This will make you right on for the extreme sats, but now you'll be off by 0.6 deg on the south sat. It's easy to fix the south sat without affecting your extreme east/west sats, however, by tilting the motor rotation axis down toward the southern horizon by that 0.6 deg (ie using 33.9 instead of 33.3 for your latitude). This action is orthogonal to, and won't affect the aim at your east/west sats, much the way the rotation of a bicycle wheel doesn't affect the aim of the wheel's axle. So now, the calculation at the southern sat, using 33.9 instead of 33.3 for your latitude, and 4.8 instead of 5.4 for declination is now :
90-33.9=56.1, and subtracting the 4.8 deg declination, the 56.1-4.8=51.3, again ~ equals the 51.2 elevation of your south satellite. But now, you'll be tracking across the arc with less than a tenth of a degree error. To set the 4.8 declination, you use a 40-4.8=35.2 deg dish elevation.

The beamwidth of these little 3' dishes is big enough that many people won't notice a 0.6 deg error, particularly if they have "adjusted it a bit trying to compromise between southerly and extreme sats, however if you've rounded off to the nearest degree, you can be starting off a whole degree off if you don't use the modified method. So to me, it makes sense to at least be starting off closer to where you want to eventually be.

?? confused-er and confused-er ??

 

[AcWxRadar]

Drboyd,

To help explain. Now let's do it with the modified declination angle:

Your latitude is 33.32°N.

Set your motor latitude to 33.32° + 0.6° = 33.92°

The motor manual chart shows your declination to be 5.4° for this latitude.

Subtract 5.4 from 40° (40° is the bend angle of the motor tube for your specific motor).

40 - 5.4 = 34.6°. Since we added 0.6° to the motor latitude angle in the earlier step which aimed our entire dish assembly higher, we need to compensate for that here and aim it that much lower via the dish elevation, so remove 0.6° from 34.6° = 34.0°

Set your dish elevation angle to 34.0°

RADAR

 

[AcWxRadar]

The purpose of this instruction is to track the ENTIRE arc of the satellites.

What we don't envision in our minds eye is that because of the geometry of the earth and how we view this satellite arc from our own reference point, is that it no longer becomes a simple arc of a circle, but more akin to some form of a logarithmic curve or a hyperbola. It is not a perfect arc for a circle because we we are not viewing it (the arc) in a planar respective. We need to consider a three dimensional view of the arc, not a two dimensional view as we would draw on a piece of paper.

RADAR

 

[B.J.]

...
....

40 - 5.4 = 34.6°. Since we added 0.6° to the motor latitude angle in the earlier step which aimed our entire dish assembly higher, we need to compensate for that here and aim it that much lower via the dish elevation, so remove 0.6° from 34.6° = 34.0°

Set your dish elevation angle to 34.0°

RADAR

Well my head is spinning.

If my brain is still working right,

Ie lower declination means dish is aiming higher.
Increasing latitude angle means elevation is lower and dish is aiming lower.

I think that by adding 0.6 to the latitude angle, you are decreasing the elevation angle, and that aims the dish assembly lower not higher, so that compensates for INCREASING the dish elevation by 0.6.

Anyway, I think the elevation angle should be 35.2 .

I have to start my brain over from scratch every time I think of this stuff.

 

[AcWxRadar]

Well my head is spinning.

If my brain is still working right,

Ie lower declination means dish is aiming higher.
Increasing latitude angle means elevation is lower and dish is aiming lower.

I think that by adding 0.6 to the latitude angle, you are decreasing the elevation angle, and that aims the dish assembly lower not higher, so that compensates for INCREASING the dish elevation by 0.6.

Anyway, I think the elevation angle should be 35.2 .

I have to start my brain over from scratch every time I think of this stuff.

B.J.

Now you are supposed to be explaining this specialty to me, not the other way around! The idea of the modified declination angle is something that I learned from you, but I wasn't sure if I put the "add" and the "subtract" in the right places.

Obviously, if you physically "RAISE" the motor you will point the dish higher in the sky. But, this means that the reading on the latitude scale will be lower in degrees. The scale indicating the motor's elevation will read a higher degree since the latitude and the elevation scales are inverse of eachother in the range from 0 to 90.

In any manner, for your modified declination approach, if you subtract from 0.6° from one side you have to add it back to the other or vice versa. So, if you raise the motor angle 0.6°, you have to lower the dish angle 0.6° or vice versa.

RADAR

 

[drboyddrboyd]

See what I mean about reading too much? Ouch!

OK, I'll add the .6 to my motor latitude, so my motor shat will be pointing .6 degree above the north star. or 33.92 above north horizontal.

What's the frame of reference for y'all's measurement of the dish elevation angle? I really don't see how it can be 35.3 from south horizontal....

 

[AcWxRadar]

Drboyd,

To help explain. Let's do it by the manual first.

Your latitude is 33.32°N.

Set your motor latitude to 33.3°.

The motor manual chart shows your declination to be 5.4° for this latitude.

Subtract 5.4 from 40° (40° is the bend angle of the motor tube for your specific motor).

40 - 5.4 = 34.6°.

Set your dish elevation angle to 34.6°.

I wanted to explain the modified declination angle notion, but I am not sure that I have it correct. I will allow B.J. to state this so that I don't make an error.

RADAR

Let's just do it this way for now. We'll explain the finer points and the modified declination setup AFTER you get this technique figured out. B.J. and I want you to make the best out of your alignment, but you will do just fine for starters if you just follow this approach, this way we don't confuse you.

Later, we can discuss this notion and you might understand what we are trying to say.

RADAR

 

[AcWxRadar]

See what I mean about reading too much? Ouch!

OK, I'll add the .6 to my motor latitude, so my motor shat will be pointing .6 degree above the north star. or 33.92 above north horizontal.

What's the frame of reference for y'all's measurement of the dish elevation angle? I really don't see how it can be 35.3 from south horizontal....

Drboyd,

What is this north star reference that you keep elluding to? Is the motor shaft (tube) on your motor facing upwards like a STAB HH 90 or 120 motor?


RADAR

 

[SatelliteAV]

What's the frame of reference for y'all's measurement of the dish elevation angle? I really don't see how it can be 35.3 from south horizontal....

Does your dish have an elevation scale stamped on the butterfly / post mounting bracket? If not subtract your dish offset from 35.3 and set the dish at this angle. Use your digital angle finder placed on a straight edge placed on the rim of the vertical axis of your dish.

 

[drboyddrboyd]

The tube actually points down, but it rotates (in its offset way) around an axis that I think of as pointing toward the north star.

Or a little above the north star.

Dang, I'm not an idiot here, but this three-dimensional conic section geometry is making my brain sweat!

Drboyd,

What is this north star reference that you keep elluding to? Is the motor shaft (tube) on your motor facing upwards like a STAB HH 90 or 120 motor?


RADAR