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Old 25-02-2009, 01:08 AM
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gary is offline
Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,444

Originally Posted by nightstalker View Post
no luck again

ALT REF=+90 or ALT REF =90 ?

Both ways it still moves as per directions .. 90 reducing as i go down towards the horizen.
Do I have to have the mount set to fork ?? when I do all this .

az motion seems way off tonight.. no matter what i seem to change it dosn't make a differance ??

any thoughts most welcome
Hi Graham,

On your Dob you will set the SETUP MOUNT parameter to ALT/AZ DOBSONIAN.

On your Dob, you will push the scope to the vertical stop and use
ALT REF = +90.

The encoder direction sense signs are the +/- signs in front of the
encoder step counts in SETUP ALT STEPS and SETUP AZ STEPS.
There are what you are trying to determine. You will not be reversing the
sign in SETUP ALT REF. You will be keeping that at +90. What you will
be doing is changing the signs in SETUP ALT STEPS and SETUP AZ STEPS.

When you dial up MODE ENCODER, observe the left-hand displayed
value. Initially, it should be +90. As you move the OTA down in Alt
only toward the horizon, it should decrease, +89, +88, ... +1, +0.
If it increases, i.e. +91, +92, then reverse the SETUP ALT STEPS sign and
repeat the procedure.

Once the Alt encoder sign is established, you are going to perform a two
star alignment and then point the OTA to the intersection of the meridian and
celestial equator. You are then going to DIAL up MODE RA DEC
(not MODE ENCODER). As you sweep across the celestial equator toward
the eastern horizon, RA should increase on the display. if it decreases, then
reverse the SETUP AZ STEPS sign and re-perform the FIX ALT REF step
and two star alignment.

Keep in mind that in the end that there are only four combinations of signs
(+ +, + -, - +, - -). The above procedure will establish them for you, but
in the worse case you can always simply try all four, recoding your results
with pen and paper as you go.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Phone +61-2-9457-9593
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