[PRejto (Peter)]

I know there have been a few posts about this here in past months but I'm not finding those posts easily.

It seems that no matter what I do I cannot improve PEC on my PMX. My results seem to always worsen PE. I have done the following:

1. Camera is within 2 degrees of position angle = 0, ie, X axis is aligned with RA.
2. Turned off protrack and I am very well aligned in PA (few arcsec)
3. collected data close to zero degrees dec, near meridian
4. calibrated autoguiding in CCDSoft, then turned off corrections in X and Y
5. collected 10 min of tracking data in .5 sec exposures
6. measured PE in TSX as 2.2 to 2.4 arcsec uncorrected (depending on which night I have collected data)
7. generate PE curve, saved to mount. I have done this for both West checked/unchecked
8. measure error with PEC enabled.
9. cry

I have tried for 3 nights with zero success. My image scale from plate solves is .54 arcsec. I could try binning 2x2 (1.08 arcsec) and longer exposures. Is my problem that I'm just chasing seeing? Would longer exposures average out seeing? Or, say if I collected 20 min of data would the software be better able to extract the true PE curve and possibly be less effected by seeing?

My uncorrected PE seems very good, but it looks to be a quick repeating cycling through of the pinion gears that waves up/down within 2.4 arcsec. In other words, two different curves, one slow and one rapid superimposed over the slow curve. I wonder if the mount is actually able to correct for the pinion error? Is the change too fast? I will attach a photo of the raw data for PE.

Any help would be much appreciated. I used the mount and my TEC140 successfully at f7 and got pretty good stars, but now at f14 I just cannot guide out these errors.

Thanks,

Peter