Help with motor setup

[rcdif]

I am having a hard time fallowing the ark. Can only get 97/125. When moving west I have to elevate dish when moving east lower dish. Tried moving dish a little to right and left then readjusting elevation but that did not help. Have had this set up working good in the past but not now. I am sure the mast is plumb. Do not know what to try next, starting to think maybe something is out of whack with dish or motor. Not sure how to check it out. Motor is mounted to dish properly motor elevation is set to my lat (even tried changing lat adjustment on motor + -) Any suggestions would be greatly appreciated at my wits end.

Fortec Star 90cm, Stab HH90 motor, IvacomQPH 031 Cool sat 7000 PVR.

 

[AcWxRadar]

I am having a hard time fallowing the ark. Can only get 97/125. When moving west I have to elevate dish when moving east lower dish. Tried moving dish a little to right and left then readjusting elevation but that did not help. Have had this set up working good in the past but not now. I am sure the mast is plumb. Do not know what to try next, starting to think maybe something is out of whack with dish or motor. Not sure how to check it out. Motor is mounted to dish properly motor elevation is set to my lat (even tried changing lat adjustment on motor + -) Any suggestions would be greatly appreciated at my wits end.

Fortec Star 90cm, Stab HH90 motor, IvacomQPH 031 Cool sat 7000 PVR.

Rcdif,

Do you have a dial inclinometer with a magnetic base? One of those round angle pointer dials? If you do, slap that baby on both sides of the motor mounting bracket and ensure that it is plumb there.

Your mast may be plumb, but if the motor bracket has any deformity you will detect it here.

Then, drive the motor to zero degrees (true due south) and check that the dish is also vertical with the motor axis.

On one of my SG-2100 motors I got a little carried away and overtightened the motor clamps. I was trying to set up a 1M dish and it was so heavy that I made the mistake of trying to pull the entire weight of the motor + dish + LNBF up with the clamps and I deformed the motor bracket.

Now I always check the plumb (at least the east and west side) of the motor bracket to be certain.

It does sound like your azimuth is off, but you said you already tried to compensat for that. I think you are going in the right direction there, but maybe you have some other angle that is off as well.

Recheck every angle that you can. Pay particular attention to the dish mounting bracket where it attaches to the motor tube and make sure that it is in direct alignment with the vertical axis of the motor tube.

I cannot say that any of these items are the source of your error, but they are something for you to check.

RADAR

 

[Lak7]

When moving west I have to elevate dish when moving east lower dish.

That sounds like you are not properly aimed South
See diagram in upper right of Pic....

 

[rcdif]

Radar Thanks for the tips, like Looks like the bracket that mounts the motor to the mast is bent. this is throwing every thing out. I take it that when the motor is set to "0" due south the dish should be plumb vertically and when viewed from the rear the lnb mounting bracket should be parallel to the mast. Both are out on my dish set up Am I on the right track?

 

[B.J.]

.... I take it that when the motor is set to "0" due south the dish should be plumb vertically and when viewed from the rear the lnb mounting bracket should be parallel to the mast. Both are out on my dish set up Am I on the right track?

No. There is no general relationship between proper motor elevation and the angles of the dish and or lnbf arm or bracket. These are defined by all sorts of parameters such as your latitude, declination, the offset angle of your dish, the connection points of your particular dish, etc, etc. THe best place to put the inclinometer is on a motor surface that's either parallel or perpindicular to the motor shaft coming out of the motor (not the bent part). This should either give your latitude plus 0.6 degrees, or 90 minus that angle, depending upon how it's measured.

 

[rcdif]

Hate to sound so stupid but to make sure I understand correctly should the dish be plumb vertically (top of dish to bottom of dish) when motor is set to "0" or does this vary from dish to dish

 

[AcWxRadar]

Radar Thanks for the tips, like Looks like the bracket that mounts the motor to the mast is bent. this is throwing every thing out. I take it that when the motor is set to "0" due south the dish should be plumb vertically and when viewed from the rear the lnb mounting bracket should be parallel to the mast. Both are out on my dish set up Am I on the right track?

Hate to sound so stupid but to make sure I understand correctly should the dish be plumb vertically (top of dish to bottom of dish) when motor is set to "0" or does this vary from dish to dish

Rcdif,

Yes, you are on the right track here. When the motor is positioned at the reference position or 0 degrees, everything should be plumb and square and the LNBF support arm should be in-line (parallel) to the mast. I am sure that a small amount of error probably isn't unexpected, but if you have over 0.6 degrees of error, I think you are going to detect problems with tracking the arc.

If you can detect that the dish isn't vertical when the motor is at zero degrees by just looking at it, then that would be a major error.

During my first motorized installation, I had a hard time figuring out why my arc was off. I eventually found that when I was trying to tweak the dish elevation at a sat that was east or west from true south, the weight of the dish and LNBF would torque on the dish bracket and either rotate it on the motor shaft or twist the mounting bracket just slightly and throw my alignments off.

I made some modifications to my dish (basically I added a screw jack assembly to adjust the dish elevation) and I make elevation adjustments only when the motor is at zero degrees. This made a world of difference.

If your motor bracket is also bent or twisted, this is definitely going to create a problem. This is the same as having a mast which isn't plumb. If you can straighten this or replace it, you will have better results.

I really like the Sadoun DG series motors as the motor brackets are at least twice the gauge thickness and won't bend.

RADAR

 

[AcWxRadar]

No. There is no general relationship between proper motor elevation and the angles of the dish and or lnbf arm or bracket. These are defined by all sorts of parameters such as your latitude, declination, the offset angle of your dish, the connection points of your particular dish, etc, etc. THe best place to put the inclinometer is on a motor surface that's either parallel or perpindicular to the motor shaft coming out of the motor (not the bent part). This should either give your latitude plus 0.6 degrees, or 90 minus that angle, depending upon how it's measured.

Hi B.J.

I was referring to the errors in the dish attachment to the motor tube and in the dish elevation bracket (side to side), also the motor bracket. What it sounds like to me is that Rcdif's dish isn't truly square or properly vertical/plumb when viewed or measured from a front view. I am assuming that these errors are not large, but enough to affect the tracking of the arc.

You are thinking about the elevation angles and such when viewing the dish from a side angle. Angles like the dish elevation or motor latitude setting. I am not inferring that these angles are off, although they need to be inspected, too.

RADAR