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AP900 upgrade question

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#1 Jesus Munoz

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Posted 04 January 2013 - 01:44 PM

Hi,

I'm planning to buy an AP900 QMD. Is it possible to upgrade from QMD to GTO?

Thanks

#2 gillmj24

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Posted 04 January 2013 - 02:39 PM

No.

#3 mgwhittle

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Posted 04 January 2013 - 03:29 PM

If you go to the AP website there is a page in there (can't find it right now....but I've seen it recently) that explains why it is not an upgrade option. IIRC it is because of a change in the drive motors and the QMD cannot be retrofitted to the new servo motors without machining work that would make it cost more than just buying a new GTO.

#4 Jesus Munoz

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Posted 04 January 2013 - 03:50 PM

Bad news. I'll check the Astro-physics page. Thanks!

#5 orlyandico

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Posted 05 January 2013 - 01:51 AM

you can do a GoTo conversion with the Boxdoerfer, FS2, Littlefoot, or SiTech systems.

here is my AP600QMD conversion
http://orlygoingthir...-go-to-conve...

i was planning to buy a 900QMD (they go below $4K) and convert it to GoTo as well... but the thing is the old QMD mounts don't have the quality of the new GTO mounts. My QMD has quite a bit of declination stiction which makes guiding not trouble-free.

also for comparison.. my AP600E QMD has a periodic error of around 11" peak-to-peak, and according to some folks on the AP-UG yahoo group, some old AP900 QMDs had PE in the 30" range, albeit smooth.

by comparison, the Mach1 I ended up getting has 2.5" of periodic error. And that's before periodic error correction.

so the new GTO mounts are really much more than just a GoTo version of the QMD mounts. They have numerous mechanical improvements that aren't immediately obvious.

#6 Tom and Beth

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Posted 05 January 2013 - 02:10 AM

Bad news. I'll check the Astro-physics page. Thanks!


If you're a visual observer, these QMDs are a solid mount that can be picked up for less than half the GOTO versions sell for. My 1200 is about 20 years old, yet any tech help is a phone call away.

#7 orlyandico

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Posted 05 January 2013 - 07:32 AM

That's a very good point. For visual the QMD mounts are great and you won't notice any declination guiding issues.

Further - I realized that if visual is all you want, converting to GoTo is not the best option. It would be better to just buy an Argo Navis for the mount. I did try a JMI computer, and didn't like the experience. But Argo Navis is the best. And in retrospect, I should have gone for it.

#8 Jesus Munoz

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Posted 05 January 2013 - 08:58 PM

Thanks for your answers Orlyandico, Tom and Beth. I'm an astrophotographer now using a Takahashi EM-200 Temma 2 and a Tak FS-102 (excellent setup BTW), but I want more payload capacity because I'm planning to experiment taking nightsky images with an Orion XT-10. Very interesting point about the periodic error orlyandico.

#9 orlyandico

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Posted 05 January 2013 - 11:38 PM

in my experience.. knowing you already have an EM200 and based ony my AP600E QMD.. you should probably go for an NJP/JPZ. or an AP900GTO. There is one for $6K on the mart right now! (but it is a GTO CP1, not the current CP3 - I don't think that should be an issue)






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