So, to wake up this thread a little bit with some more observations and maybe even some eye candy (ok maybe not exactly eye candy lol).
So, I've had a chance to use the mount for a few nights this past couple weeks and play around with guiding.
First observation relates to APT and plate solving. As mentioned in my previous post, APT allows you to avoid sending a sync command to the mount (which apparently has some issues) after it plate solves and does gotos. One correction to my previous post however, the setting for Make Relative Goto++ Moves needs to be checked, not unchecked. If you don't check it, APT (or synscan, don't know which) has trouble using absolute gotos to zero in on targets close to the meridian.
I have also been fiddling with the guide speed. I had originally set it to 1x sidereal, which worked ok but I noticed occasional RA spikes. Once I dropped the guidespeed to 0.75x, the RA graph smoothed out. I'm guessing that either stiction or backlash was causing the RA spikes, since at 1x the motor actually stops when given east commands.
However, the slower guide speed exacerbated the issue with DEC backlash. As I had mentioned before, I had some issues with DEC calibration which I attributed to a tensioner nut that was too tight. But even though it did calibrate better, I noticed quite a bit of backlash in dec, causing occasional guiding jumps. Switching the guide speed to 0.75x made the corrections even slower, which made the backlash effects worse.
So, I'm going to try and see if I can reduce that. Tightening the tension nut didn't seem to have much effect. I noticed that the reduction gears seem to have some play in them, but I don't see a way to adjust them. So I'm going to try some heavy grease (an old Chinese mount trick) to see if it helps.
One thing I did to improve dec calibration was specify larger calibration steps (>1000 ms) in PHD. It seems that PHD automatically sets its own calibration steps based on entered guidescope fl and pixel size. So I cheated by changing the scope fl to a smaller value to achieve the calibration step size. But this messed up my arcsec display values in the PHD graph If anyone knows how to make PHD override its automated calibration step size, let me know.
Anyway, other than those minor annoyances, the mount guides well enough (somewhere around 1.5-2 arcsec rms). So, without further ado, here's the two images I took over those nights (click on each pic for the info and stats):
All in all, a pretty decent mount for the money still.
Hope this helps.
Edited by dciobota, 30 October 2018 - 04:24 PM.