Thanks for the very clear & concise explanation Michael. I understand completely now.
In thinking about trying to "trick" true south & your comments in the earlier post, I overlooked the fact that the motor elevation decreases at the east/west extremes of the arc.
I wonder why the satellite rotor engineers don't try to design more range into their products? For instance, if
Stab can deliver 60 degrees each side of true south, why doesn't SD3D12 (only 45) offer the same? Ham radio or even cheap tv antenna rotors rotate nearly 360 degrees - but of course they don't have to deal with the elevation change.