From: "KirkusMcGurkus" <kirk@stenvall.net>

Date: October 1, 2008 12:11:59 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: Custom drive ratios disrupt tracking?


--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@...> wrote:


Dear KirkusMcGurkus;


On 1-Oct-08, at 1:08 AM, KirkusMcGurkus wrote:


I have an LXD75 that I've recently modified by replacing the motor

drive gears with a belt drive system. In doing so I've changed the

drive ratios in my Autostar. Can these changes cause tracking errors

with AstroIIDC?


I would imagine it could.


The reason I ask is that the last 2 nights, since modifying my mount,

when I begin tracking a star, both RA and DEC run off course by what

seem to be near equal amounts and in a very consistent manner.


Which version of Astro IIDC?


3.02.03



When observing the tracking star visually it moves off course very

slowly... my initial alignment has been good. But as soon as AstroIIDC

takes over (following successful calibration), these very consistent,

smooth errors in both axis appear. I have a screenshot if it would

help to clarify what I'm saying.


Are you sure it successfully calibrated? Did you watch the whole  

process to see if when it stops moving that the Red cross over the  

star is in the right place and not offset?


I'm really not sure that it calibrated successfully. If I set the wait

time in the calibration box to around 5 sec. or less, I get a "No

movement in DEC up or down" error. If I set the time longer, it does

eventually move and continue with calibration (lag problem?). I do

watch the calibration, though. And the Red cross is always over the

guide star after each movement.




Also have you re-balanced your mount after all these modifications? I  

seem to recall you trying to guide with a 10" Scope which severely  

over weighted the mount and had tracking issues then too, is that the  

same thing now?


LOL. No. I'm no longer using the 10" on my LXD mount. It's sitting in

it's DOB mount where it feels more comfortable. I'm using the 6" SN

that came with the LXD mount.




I guess I'm wondering if something needs to be modified in my

AstroIIDC software to compensate for the modification to my mount.


There is likely nothing we can change. We tell it to move for z  

period of time it is supposed to consistently move for z period of  

time. If it's inconsistent for movement or there is a lot of Lag /  

Delay then it won't track well that's all there is to it.


BTW, the new drive ratios, when using the mount without tracking, are

spot on.


That doesn't really mean much. Guiding needs repeatable consistent  

motion and if there is any lag / delays or over runs in motion, it  

won't track.


I guess I was just curious if AstroIIDC assumed the LXD ratios would

be at their defaults and perhaps it was sending info to the mount that

was incorrect due to the modification. It sounds like the ratios don't

matter to AstroIIDC. It just expects the mount to move when it says move.


When tracking is started does AstroIIDC take control of the mount away

from Autostar? The reason I ask is that as soon as tracking is

started, that's when the guide star begins moving in the video preview

-- on both axis. As soon as tracking is stopped, the guide star stops

moving in the preview window and remains stationery.


Milton J. Aupperle