Motorised 80 cm dish elevation settings

[sp2907]

Hi all,

I have recently replaced my H-H Manhattan mount which failed after approximately 14yrs of good service with TM-2600M3 motor. Unfortunatelly I've lost all the stellites after installing the new motor. As this is almost a like-for-like replacement I thought it would be a straight forward job. The only difference between the two mounts is that the mounting tube in the new motor is facing down where the old one was facing up. Does this difference affect the old elevation angle set on the dish which I haven't changed? I have an ISS 80cm dish installed on a pole mount which is in good condition with a new LNB and a clear line of site between 30E to 30W. The motor elevation is set to 39 as given by the manual for my current location 51N, 1.3W. The elevetion angle on the dish is set to 67. Is this correct? Any comments on this would be much appreciated.

 

[Lazarus]

Dish bracket should be set to about 25 deg. prior to final alignment.

Personally, I'd ignore the Elevation scale on the motor and just use the Latitude scale - ie Set the motor to 51 on its Latitude scale. That said, 51 on the Latitude scale is equivalent to 39 on the Elevation scale, according to the Motor's settings table. But do check the scales are correct - A common error is to set the intended figure against the wrong scale!

 

[sp2907]

In my case for the ISS dish bracket it should be set to 65 deg. marking (90-25), I guess?

 

[Lazarus]

In my case for the ISS dish bracket it should be set to 65 deg. marking (90-25), I guess?

As stated, dish bracket should be set to 25 prior to final alignment. Not 65.

You can see if it's in the ballpark as the dish face should be close to vertical. If it's pointing way up in the air, it's wrong.

 

[sp2907]

Lazarus, the ISS dish brackets have got the elevation markings the other way round. When the ballpark is on 90 marking then the dish is in parallel with the pole mount. When on 25, the dish is almost verical and will point to space. So in my case, the 25 deg. corresponds to 65 marking on this dish bracket. I've attached some photos for better understanding. I want to clear this out before I get up on the ladder again. As you can see it is not very comfortable to spend a long time up there fiddling with these settings without a decent meter.

 

[Lazarus]

That suggests to me that, in common with many other similar dishes, the dish bracket can be assembled in two ways, to cater for use in different latitudes, and that it might be assembled the wrong way up for UK use.

No matter, though, as you can ignore the assembly and the markings simply by setting the dish face vertical and finalising the alignment using that as your starting point.

With it set to your suggested setting of 65, is the dish face near vertical? If so you'd be good to go for your final tweaking.

BTW, the precise dish angle is actually 22.6 (or, by your method, 67.4), but as you need to tweak anyway and also there are bound to be angular errors elsewhere, I always kick off from 25.

 

[jeallen01]

Lazarus, the ISS dish brackets have got the elevation markings the other way round. When the ballpark is on 90 marking then the dish is in parallel with the pole mount. When on 25, the dish is almost verical and will point to space. So in my case, the 25 deg. corresponds to 65 marking on this dish bracket. I've attached some photos for better understanding. I want to clear this out before I get up on the ladder again. As you can see it is not very comfortable to spend a long time up there fiddling with these settings without a decent meter.

If the last photo shows the dish pointing at your most Southerly sat, which is Thor at 0.8W, then it looks to be tilted back too far - should be much nearer the vertical (my location is 51.2N 0.4W, so not that far from you, and my steerable dishes are more vertical).

 

[sp2907]

Basically the original dish elevation setting which worked on Manhattan H-H mount does not directly apply to TM-2600 mount. I will ignore this and start from lowering the current dish elevation almost to vertical and work from here. Will let you know with the outcome.

 

[a33]

Basically the original dish elevation setting which worked on Manhattan H-H mount does not directly apply to TM-2600 mount

Dish elevation scale would normally be (motor shaft bend - needed declination offset angle).
So is the motor shaft bend different for the two motors?

In your case use the (90 - dish elevation scale) value.

Greetz,
A33

 

[jeallen01]

Dish elevation scale would normally be (motor shaft bend - needed declination offset angle).
So is the motor shaft bend different for the two motors?

In your case use the (90 - dish elevation scale) value.

Greetz,
A33

FWIW, I think he's already tried that, and it didn't appear to work.

 

[Lazarus]

Indeed.

His Post#8 is the way ahead - the empirical approach eliminates any confusion as long as the rough setting is in the ballpark.

 

[a33]

Well, is there a difference in motor shaft bend, or not?
I didn't read about it.
But I'll leave it to you guys, then.

Greetz,
A33