Re: AP600 RA Backlash


The RA and Dec backlash settings are retained in the memory and are the same
for each session. The amount of backlash can vary depending on load and
orientation of the telescope. RA backlash compensation is there mainly to
prevent the star from "drifting" excessively after reversal of the RA motor
gear train. It takes many seconds for the normal sidereal rate to take up
the motor-gearbox slack before the mount begins tracking again. For that
reason, we added a short pulse of 64x sidereal to get the gearbox to
re-engage quickly. It can never be precisely set, so there will always be a
small delay or small overshoot.

For declination, there is no problem because the dec axis does not "track"
or move after reversal. Normally, dec backlash is adjusted only for manual
guided astrophotography where the scope is always in one orientation for a
long time. Even here, a different adjustment may be needed in different
parts of the sky.
Roland Christen

-----Original Message-----
From: Chris Spratt [mailto:cspratt@...]
Sent: Saturday, May 13, 2000 6:28 PM
To: ap-gto@...;
Subject: [ap-gto] AP600 RA Backlash

I've noticed that when I "train" my RA backlash that the number I
chose one night isn't good the next. I thought that once calibrated
the RA backlash number would be retained for each session. Now I have
to reset it each observing session. I'm using version 2.6 of the
software (mount came end of March 2000).

On my mount the range at 12x runs from 4-6 with 5 the median most

The balance of the 8" OTA and attachments I'm using appears to be

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