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PEC on Meade LXD-75-does it work?

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#1 Richard Turner

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Posted 04 June 2009 - 03:10 PM

This question might have been addressed before. I have an LXD-75 mount. The manual says to "park" the scope to train the PEC. I did that, and trained the PEC on a guide star with an illumintated reticle. :confused: After the training the mount did not track any better than with the PEC turned off. Am I missing something, or does the PEC function just not work?

Thanks,

Richard Turner

#2 hfjacinto

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Posted 04 June 2009 - 03:13 PM

I trained PEC on my LXD 75 and it didn't do anything. The scope tracked nice before, it still tracks nice.

#3 jrcrilly

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Posted 04 June 2009 - 03:32 PM

After the training the mount did not track any better than with the PEC turned off. Am I missing something, or does the PEC function just not work?


What tracking error were you noticing before? If was DEC drift it'll still be there; that isn't related to periodic error.

#4 Richard Turner

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Posted 04 June 2009 - 04:58 PM

John,

I had the scope fairly well polar aligned, and the drift was in RA, east-west, due to the periodic error in the worm. Another poster related that their LXD-75 tracked nice. The tracking in my unit was also quite good. I just thought PEC might improve it.

Richard

#5 jrcrilly

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Posted 04 June 2009 - 05:48 PM

the drift was in RA, east-west, due to the periodic error in the worm. Another poster related that their LXD-75 tracked nice. The tracking in my unit was also quite good. I just thought PEC might improve it.

Richard


It definitely should improve PE. If you could see PE in the eyepiece then it is very severe or you were using very high magnification, though. The key to distinguishing PE from drift is to check it 8 minutes apart. PE will repeat and the object will be brought back to precisely the same place. If it's drift then the object will move and never come back to the same place in the eyepiece.

Did you (1) train for one full worm cycle and then (2) wait through another until the next cycle after that? That's when the correction begins.

#6 Richard Turner

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Posted 04 June 2009 - 06:45 PM

John,

I did train for the entire cycle. After that I went from "PEC train" to "PEC on" to observe the results.
I did not see any improvement. Perhaps my polar alignment was not accurate enough.

Would this be the correct procedure for the next clear night?

1. Obtain a highly accurate polar alignment.
2. Make sure mount is balanced or with a slight levereage to
the east. Obtain a star alignment.
3. Observe the amount of period error amplitude on a star
near the equator with the 12mm illuminated eyepiece.
4. "Park" the scope.
5. Do "PEC train" for an equatorial star for the full worm
cycle.
6. After training, enter "PEC on" mode and observe if the
periodic error is reduced from non-pec.

Thanks,

Richard

#7 milky_way

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Posted 05 June 2009 - 10:33 PM

After the training the mount did not track any better than with the PEC turned off. Am I missing something, or does the PEC function just not work?


What tracking error were you noticing before? If was DEC drift it'll still be there; that isn't related to periodic error.


Just wonder what is the reason causing a DEC drift and any solutions for such a problem?

#8 Richard Turner

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Posted 06 June 2009 - 12:44 AM

I'll try for a very accurate polar alignment to greatly reduce declination drift. I think the scope is supposed to be parked after the PEC is trained. The hand control prompts that the scope should be turned off after parking. Upon power up, the PEC should work.

#9 Richard Turner

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Posted 08 June 2009 - 06:38 PM

Well, I found out that the PEC does indeed work. I tried a training session, then parked the scope. Upon power up, the PEC then worked.

R. Turner






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