PHD Dec all over the shop!

[Spoon]

Right that may have actually been the problem then!

[ChrisLX200]

Right that may have actually been the problem then!

I should not cause a progressive drift though, when you calibrate PHD will be working out how far to move the mount to move the star a certain distance on the chip, so if you move to another section of sky that figure will be wrong - it will either under-correct or over-correct. It will tend to oscillate back and forth as it tries to correct for the previous error. I doubt this would ever amount to huge amount though.

ChrisH

[old_eyes]

I had a similar problem sometimes, and agree with others that you don't want perfect balance. It seems to be more robust if you are a bit heavy on one side in both RA and DEC.

old_eyes

[ollypenrice]

I had a similar problem sometimes, and agree with others that you don't want perfect balance. It seems to be more robust if you are a bit heavy on one side in both RA and DEC.

old_eyes

Not 'on one side' but on the east side for RA. This makes the payload sit on the pushing side of the worm gear. Dec is not so simple because being, say, camera end heavy provides the same anti backlash effect till you are on the zenith but then the imbalance disappears because the scope is vertical.

Olly

[Oldbear]

I had a session last night (I actually played with this until dawn!) and had similar problems.

I don't have screen shots, though I will next time, I promise!

My graph in PHD 1.13 looks fine and normal, reasonably acceptable for guiding.

My graph in PHD2 has an alarming pattern with an apparent wild DEC square wave with swings/cycle about every 3 minutes (though not quite regular enough to completely ascribe to PE).

My polar alignment and 3 point alignments (EQMOD) were fine and I was guiding near Vega for a reliable target star with nearby suitable guide stars.

I am suspecting that this is a DEC backlash problem, though why it isn in PHD2 and not in 1.13 I can't explain.

Oldbear