Sharp dec spikes with DDM85

[Francisco Rodriguez-Letter]

Hi folks,

I was wondering if anyone had any ideas...I have an issue with sharp spikes in dec when guiding. I use a DDM85 and have been getting these occasional spikes which morphologically look like dithering in PHD2. You can see from the graph that one of them came from dithering which is to be expected but the others are not. They occur during image capture and are causing me lots of issues. I haven't changed my setup in a year but the problem has arisen over the last couple of months. I'm wondering whether there's an issue with the grease in the motor. I live in Australia so to send the unit back to Europe is no easy task. I'm using a 14" planewave CDK mounted with a beefy 4" focuser and FLI 16803, definitely light enough for the mount. I don't think it's a cable snag issue. The scope is mounted in a backyard observatory on a very steady 600mm diameter concrete pylon.

Any advice would be greatly appreciated!

Thanks,

Franco Rodriguez

[robertp]

Hi Franco,

could you post a servo-log-file from that session? Can you say at roughly what intervall the peaks show up?

Best regards,

Robert