PH2 and CGEM mount RA issue

[Omega62]

My new to auto guiding
I have a Celestron CGEM mount and am using PHD2 with ZWO ASI 120MM as a guide camera. I have the ZWO plugged into the guide socket on the mount. All connect Ok in PHD2 and it calibrates too.
I'm having major issues with the RA axis it guides OK for 30sec then starts to drift. If I have the RA auto guide rate set above 1% in Nexstar it won't guide in RA at all.

[billdan]

Hi Andrew,

I'm not familiar with a CGEM mount, but from looking at your graphs it appears that the mount is not responding to the guide commands in RA.

Are you certain it calibrates OK?, i.e. does PHD move the mount West approx 12 steps and then return to the East before it calibrates DEC. You have to adjust your calibration step size in millisec to get about 12 steps, my old EQ6 was set to 750mS.

Another thing, use guide exposures around 2 secs or more, any less and you are chasing the seeing and the mount will not respond quickly enough.

Good luck
Bill

[kens]

It does indeed appear to be not responding to the guide commands.
I'm not familiar with your mount but if the hand controller is saying your RA rate is 1% Sidereal that is VERY low. It should be between 50% and 100% of Sidereal.
Also, your exposures are way too low at 0.1s - try 2s
Can you post your guide log? It gives a lot more information

[ChrisV]

+1 check handcontroller has at least 50% for autoguiding. And then check it is the same rate in phd2 - it should be set automatically in phd2. It does this when I use an ascom connection with a cgem mount ( found this better than direct from camera with the st4).

Or maybe you have a dodgy st4 cable?

[vlazg]

Hi Andrew,
Apart from all the other suggestions, your RA aggression seems very high ( 200 ), try dropping to about 90 and increasing your hysteresis to about 50. See if this helps.