Re: LX200: Dec Backlash
| Subject: | Re: LX200: Dec Backlash |
| From: | Richard G. DAVIS |
| Date: | Thu May 02 05:32:29 1996 |
Pgoelz@aol.com wrote:
>
> Hi Burl.....
>
> I will let the users here who have more direct experience with the finer
> points of the dec drive answer your questions in more detail, but suffice it
> to say that it would seem that something is mechanically wrong with your dec
> assembly. You should have nowhere near that amount of backlash, and if you
> do, it could easily explain the pointing errors. The scope senses motor
> shaft revolutions to determine how far the DEC and RA axis have traveled, and
> if you have that much backlash, the scope could be way off in calculating the
> postion of the OTA during an align.
>
>
> Hi Burl.....
>
> I will let the users here who have more direct experience with the finer
> points of the dec drive answer your questions in more detail, but suffice it
> to say that it would seem that something is mechanically wrong with your dec
> assembly. You should have nowhere near that amount of backlash, and if you
> do, it could easily explain the pointing errors. The scope senses motor
> shaft revolutions to determine how far the DEC and RA axis have traveled, and
> if you have that much backlash, the scope could be way off in calculating the
> postion of the OTA during an align.
>
This observation is an example of why I was disappointed that Meade decided to
drop their intended output shaft encoders. With those encoders installed on the
LX200, the system would always know exactly where the RA and dec positions are.
It would then be possible for the base computer in the LX200 to recognize when
any backlash or other drive system errors are present, and then to compensate
for them in the course of normal operations.
