HH motor horizon limits

[gpflepsen]

So now that my brain is more hamburger than usual, are you saying a dish rotated on motor shaft 20 deg could remain on the arc and allow DISEqC 1.2.for positioning? I don't see how that's possible as once you rotate the dish on motor shaft, wouldn't the elevation would be off, ie arc shifted?

Do a search here for poor man's polar mount. That may show how this is possible and what a polar mount does. Remember the only motion that is happening is the dish is being rotated on the polar axis of the motor. There is not any special movement happening other than the dish being rotated so it looks down the surface of a cone that happens to intersect the arc.

Another perspective; put yourself at either the north pole or equator and see if that helps to visualize.

 

[a33]

Say your due South is 97w. You can set the motor to zero, mount and aim the dish at 87w. Motor to what USALS thinks is 107w and the dish will be pointing towards 97w.

That's just with a polar mount.
Not with a HH100 or HH120 or SG2100.
Turning a bent motor shaft DOES make a difference; you should reserve the highest point (zero-position) of the bent shaft for due south position, or you don't follow the clarkebelt.
That's how I learnt it, that's how I understand it; your reasoning on this point still doesn't make sense to me.


Only solutions for TS would be:

It has a physical limit switch. You would need to disable that inside the motor and use DiSEqC 1.2 not USALS.

and

You could get another 10 deg or so with a sidecar LNB.

greetz,
A33

 

[gpflepsen]

That's just with a polar mount.
Not with a HH100 or HH120 or SG2100.
Turning a bent motor shaft DOES make a difference; you should reserve the highest point (zero-position) of the bent shaft for due south position, or you don't follow the clarkebelt.
That's how I learnt it, that's how I understand it; your reasoning on this point still doesn't make sense to me.

greetz,
A33

The HH100, HH120 and SG2100 are polar mounts. The bent shaft does not result in any strange action to the dish. The dish is fixed relative to the bent shaft and only swings relative to the motor axis. That is all a polar mount is doing. An HH is just a polar mount with a larger range of motion than non-HH mounts.

Maybe look this over some for additional info. http://www.satsig.net/polmount.htm

 

[Jim S.]

I'm having a hard time visualizing how the dish could be tracking the arc if the apex of the arc is set anywhere other than due south...

 

[gpflepsen]

I'm having a hard time visualizing how the dish could be tracking the arc if the apex of the arc is set anywhere other than due south...

The motor has to be set just like any polar mount to satisfy two things; 1) the axis of rotation has to be set for your latitude, 2) the axis has to be set so it it in alignment with true North/South. That sets the apex at your southernmost point. These settings can never change.

This is the case if you are using a polar mount for a large C Band dish or mounting a motor with a bent shaft for a small offset dish. The geometry relationship between the motor axis and the dish's aim never changes regardless of what the connecting structure looks like.