Re: AP900 DEC sawtooth guiding

Don Anderson

What is your dither setting in SGP?
Don Anderson

From: "anismo@... [ap-gto]"
To: ap-gto@...
Sent: Thursday, September 22, 2016 7:13 AM
Subject: [ap-gto] AP900 DEC sawtooth guiding

Hi All,
I have a used AP900 mount and I finally got it setup last night for a test run. I have updated the control panel  CP3 chip to latest V2 chip.
I connected the mount using AP ASCOM v2 driver and SGP and PHD2.  I was hoping to try Pempro to do PE traning but I dont have Maxim which apparently is needed for that software to use my CCD. I need to get back to this once I figure out the DEC i
I did Polar alignment using Polemaster  and after connecting the mount with SGP and PHD2, I did PHD2 calibration and let it guide. The guiding was pretty good (under 0.5 arcsec/px in both DEC and RA - I had  Tak FSQ108 with 0.73 reducer loaded).
However, when SGP did a dither, the DEC started to go into huge sawtooth pattern (7'' swings with regular interval as the PHD2 tries to get it back). I could see the guide star jump between two points. If I stop and restart guiding, it will run properly again until another dither pulse. I tried changing min-mo, guide algorithm, dropped aggressiveness all the way to 5 but this problem seems to be there.
I am wondering if there is a mechanical adjustment (remesh?) that is needed (since it was transported). I read the AP documentation that has instructions to check if the axis has play and if I try to move the dec axis (with clutches engaged) I dont feel much play (may be a tiny amount ). 
Any thing else I should be looking for?


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