Evolution 9.25 OTA on a GGEM

[Alkor88]

Hello,
I own a Nexstar Evo 9.25 alt/az and wonder if I can get a CGEM/GGX and mount the existing OTA on it. I don't want to spend more on the Evo by getting a Pro wedge.
Best Regards,
Peter

[Merlin66]

You can easily get a dovetail to fit the C9.25 and mount it on something like the HEQ5pro (or better still the NEQ6Pro) mount.
I used the C9.25 on the NEQ6 for a few years prior to upgrading to the C11.

[Alkor88]

Thanks Ken,

I probably have to pick a Celestron mount to go with the Starsense unit which apparently can do polar alignment. I'll check out the dovetail options then.
Peter

[Merlin66]

Peter,
https://telescopeobserver.com/celestron-nexstar-evolution-9-25-goto-telescope/#Telescope_Specifications
This seems to show it's already fitted with a dovetail??

Hmmm The additional Starsense unit seems to need the "AUX" port found on Celestron Mounts (maybe a user can confirm???)

[casstony]

I stayed with Celestron so I could use the Starsense unit. The C9.25 will go straight onto the CGEM; the only reason to change to a wider dovetail is to get a bit more stability, but you can try the existing skinny (vixen) dovetail first.

The CGEM was available new for about 1200 or 1300, so shop around and try to find a good price. It is fairly heavy, about 41 pounds for the head alone.

[Alkor88]

Thanks Tony,

Sounds promising. I had no trouble with the OTA so far. The mount/drive is not so good when it comes to longer than 30s exposures. I played with the backlash settings but did not see any improvement.
As I said earlier, a wedge is another chunk out of pocket and may not improve things to the level of an EQ mount.
Peter

[Lognic04]

I have a CGEM and it is a good workhorse! Apart from some easily fixable issues it has been great.only thing is if I could swap with an eq6 I definitely would as I use this for imaging and eqmod and belt mod would be great.

[ChrisV]

Logan

Agree. The CGEM is agood workhorse - I got one of the runout ones at bintel.

In your opinion what are the fixable issues ? And how.

I changed the saddle on mine for an ADM which has the dual vixen-losmandy. Then pulled apart, cleaned and super lubed it.

Chris

[Lognic04]

My issue was an encoder disk cracking - thankfully celestron replaced this SECOND HAND(!) mounts broken disk for free!
I regreased DEC, but i could never get into RA because of the retaining ring, i recon it really has to be regreased.

[Alkor88]

Thanks for your input guys,

I have now an CGX on order which should arrive next week. It's probably a bit oversized for my Evolution tube, but I may get heavier gear further down the track (guiding).
What is a suitable power supply for this mount? Bintel and others sell a Powertech Li-Ion pack. I don't like cigarette lighter connections at all.

[Lognic04]

you can NEVER overmount a scope. In fact a 9.25 is maybe a bit over in terms of focal length and weight for that class of mount!

[Alkor88]

Logan, do you refer to the CGEM or the CGX with your above statement?
The Evo 9.25 OTA including diagonal, Hyperion 10mm and Starsense weighs in at 10.2kg. When I replace the eyepiece with a Canon 6D it still should be about the same weight. Can't imagine that being a burden for a 18kg or 25kg rated mount? Or is it?

[Lognic04]

I mean the CGX - the weight is absolutely fine - the worry is the focal length. Unguided shots will be impossible, and you will need to use an OAG.

[Lognic04]

Oh am forgetting this is for visual! then you should be golden :)

[Alkor88]

I received the CGX on Monday - pretty darn good service after ordering on the Friday before from QLD.

Unpacked the boxes at work to check content and setup the tripod for a trial. Not impressed. The leg lock levers need to be banged on really hard to prevent the lower section of the leg to slip back in when load (my upper body) is applied to the mount. There was also some additional spread of the fully extended legs noticeable on a smooth concrete floor. Unlike the Nexstar mount this one has no mechanical fixing to prevent that.
Next shock came when I turned the tripod around to retract the extended legs and one slipped back into the storage position unhindered. The impact dislodged the leg tip (aluminium cast) and send it bouncing over the floor. They are only glued on with a few blobs of whatever kind of glue it is.
Would be disastrous to have that happening some place in the dark with lots of nooks and crannies for the bit to disappear in forever. Would render the mount unusable for the night or even weeks to source a replacement.
Fortunately one of our service techs saw the mishap and took the initiative.
He put two grub screws in each cap to secure it to the lower section of the leg and also placed a suitable o-ring above the leg cap to dampen any future impact should it occur again. Well done Grant!

The rest of the mount is working as expected. I should investigate to cannibalise the Nexstar mount legs which are mechanically far better executed.