Encoders

[Neil]

G,day , can anyone tell me what encoders do and where they are located on a Meade LX 90 mount, thanks, clear skies.

[Kunama]

Very simply:
Encoders provide information on the degree of rotation of the axis in the mount. For example, my T-Rex mount comes fitted with 4096 'tic' encoders.
Therefore for each full revolution of either the azimuth axis or the altitude axis, the encoder 'counts' 4096 'tics' and when connected to the DTC or Goto drive which is programmed to the same setting of 4096 tics this information is used to locate various objects in the database.
This requires that the mount/telescope and therefore DTC or computer is aligned initially with a known feature or two.

Never used a Meade LX90 mount......

Clear skies ............... I wish !!!

[AndrewJ]

Gday Neil
The encoders on an LX90 are mounted on the motor and are used to guesstimate where the scope is pointing, and control the motor speed feedback loops for tracking etc.
As such, many things affect the final pointing accuracy like periodic and non periodic gear errors, flexure, clutch slip etc etc etc.
ref http://jan.eaglecreekobservatory.org/dec.html for pictures of the DEC assy and its motor / encoder setup
Andrew

[Neil]

Thanks Matti and Andrew, I will check this out, clear skies.