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Equipment Discussions >> Mounts

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photonhunter
member


Reged: 02/24/07

Re: GP-DX understanding Problem (RA Axis) new [Re: John Carruthers]
      #5945841 - 06/29/13 12:47 AM

You tighten the set screw when using the polar alignment scope to use the RA ring as an hour graduation ring. Normally when observing it should be loosened.

The RA ring (with the set screw loosened) should have enough friction to follow the RA axis as it turns.


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planet9
member


Reged: 01/23/13

Loc: UK
Re: GP-DX understanding Problem (RA Axis) new [Re: photonhunter]
      #5949242 - 07/01/13 08:30 AM

hi

Do I need some kind of auto tracking or GOTO interface for the auto tracking with GP-DX mount? I have just the GP-DX fitted with RA and DEC motor and DD-1 two axis controller. I can move the scope with the controller to both axis, but I do not know how to activate auto tracking.

When stationery, I can hear the GPDX motors ticking away, so I was under impression that they are auto tracking, but when I check the EP, they are not.

Thanks.

Edited by planet9 (07/01/13 08:31 AM)


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5949379 - 07/01/13 10:11 AM

The mount will track when turned on. Remember, it will be very slow movement. For go-to you will need new motors and a new controller.

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planet9
member


Reged: 01/23/13

Loc: UK
Re: GP-DX understanding Problem (RA Axis) new [Re: rmollise]
      #5949772 - 07/01/13 02:15 PM

Is a lot slower than it should be?

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John Carruthers
Skiprat
*****

Reged: 02/02/07

Loc: Kent, UK
Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5950749 - 07/02/13 03:43 AM

how slow? it should track at 1 rev / day.

I suspect you have MT1 motors and a basic guiding handset.
If you can find an old Vixen Skysensor 2000 it might help. I fitted a Skywatcher Synscan goto drive set to my Vixen SP but the Ioptron drive set will also fit.


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planet9
member


Reged: 01/23/13

Loc: UK
Re: GP-DX understanding Problem (RA Axis) new [Re: John Carruthers]
      #5951476 - 07/02/13 03:00 PM

I will just use it as it is. I do not want to add any new GOTO or Digital accessories to the mount. It would have been good, if it was working AUTO Tracking with what it is got, but it is still good mount as is.

Thanks for your suggestion. cheers.


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rmollise
Postmaster
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Reged: 07/06/07

Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5951610 - 07/02/13 03:57 PM

Quote:

Is a lot slower than it should be?




It's a "clock" drive. It will move with a speed commensurate with that name: one revolution in a sidereal day, 23 hours, 56 minutes, 4 seconds.


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planet9
member


Reged: 01/23/13

Loc: UK
Re: GP-DX understanding Problem (RA Axis) new [Re: rmollise]
      #5951642 - 07/02/13 04:12 PM

Quote:

Quote:

Is a lot slower than it should be?




It's a "clock" drive. It will move with a speed commensurate with that name: one revolution in a sidereal day, 23 hours, 56 minutes, 4 seconds.




Yes, that is what I thought. But when I was viewing the Moon with ORION DX300, it was in the centre of the FOV. I thought the GP-DX clock drive will keep it in the centre of the FOV by compensating the Earth's movement, but it wasn't. The Moon moved away from the FOV quickly, even when the GP-DX motor was ticking away. I was using 9mm EP, which gave about 130x magnification.


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rmollise
Postmaster
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Reged: 07/06/07

Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5951738 - 07/02/13 04:57 PM

How good a polar alignment did you do?

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planet9
member


Reged: 01/23/13

Loc: UK
Re: GP-DX understanding Problem (RA Axis) new [Re: rmollise]
      #5951797 - 07/02/13 05:46 PM

Polar scope was set for rough alignment to the north, and then set for my location 52 degrees which is UK.

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rmollise
Postmaster
*****

Reged: 07/06/07

Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5952746 - 07/03/13 09:16 AM

Whether that was good enough depends on how fast the Moon moved out of the field. Center on the Moon, see how it moves, then _turn off the drive_ and see if that changes things.

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comets4tom
professor emeritus


Reged: 02/08/05

Loc: Texas
Re: GP-DX understanding Problem (RA Axis) new [Re: rmollise]
      #5953003 - 07/03/13 12:11 PM

Two other things to check for.

Make sure you have tightened the clutches on the mount (the black levers)or it will not track.

If the mount is grossly imbalanced it will also fail to track properly. You will need to check the declination balance and then the right ascension balance.

Tom H.


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John Carruthers
Skiprat
*****

Reged: 02/02/07

Loc: Kent, UK
Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5955590 - 07/05/13 03:54 AM

Quote:

Polar scope was set for rough alignment to the north, and then set for my location 52 degrees which is UK.



check your polarity, Vixen sometimes use centre negative.
Is there a N/S hemisphere switch? it may be driving backwards ;-)
If you could post a pic of your handset it will help.(or if it's marked DD1, DD3 etc?)

As mentioned above, check the balance and make sure the clutches aren't slipping. The Vixen mounts are generally very well made and smooth in operation.

If you are anywhere near Kent I could have a look?


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planet9
member


Reged: 01/23/13

Loc: UK
Re: GP-DX understanding Problem (RA Axis) new [Re: John Carruthers]
      #5968544 - 07/13/13 04:44 AM

They are working OK now. What was wrong before was, I think, the clutches were not locked strong enough on both axis. Last night I was looking at a few double stars, and made sure they are tightened firmly, and hey voila, it was tracking OK.

But after about 15 minutes, it was slightly losing tracking, so I had to follow the target manually by handset - maybe this is due to low battery power (using 8x dry cell, and the light was flashing between green and red, before it was only green) on the handset.

I will go to Argos, and buy a 12v engine starter, which also gives 9 and 12v DC out from rechargeable battery.

I see one from Sky-Watcher on eBay, but they are crazy expensive over 115 quid, and some other seller asking even twice or more of that , when the same rating power tank from Argos costs £29.95.

They are all 17Ah, so same rating, the SW one has some extra bits like radios and lights which are not essential needs. Save money, and put it towards another scope.

I am at outside of Edinburgh. cheers.

Edited by planet9 (07/13/13 07:30 AM)


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John Carruthers
Skiprat
*****

Reged: 02/02/07

Loc: Kent, UK
Re: GP-DX understanding Problem (RA Axis) new [Re: planet9]
      #5971704 - 07/15/13 05:26 AM

Maplin do a 5A 12V camera power supply ...
http://www.maplin.co.uk/xvision-12v-dc-5000ma-powersupply-535932

or I use an old PC psu.


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