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GP-DX understanding Problem (RA Axis)

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#26 planet9

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Posted 02 July 2013 - 02:00 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.

#27 rmollise

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Posted 02 July 2013 - 02:57 PM

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.

#28 planet9

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Posted 02 July 2013 - 03:12 PM

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.

#29 rmollise

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Posted 02 July 2013 - 03:57 PM

How good a polar alignment did you do?

#30 planet9

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Posted 02 July 2013 - 04:46 PM

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

#31 rmollise

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Posted 03 July 2013 - 08:16 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.

#32 comets4tom

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Posted 03 July 2013 - 11:11 AM

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.

#33 John Carruthers

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Posted 05 July 2013 - 02:54 AM

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?

#34 planet9

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Posted 13 July 2013 - 03:44 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 :question:, 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.

#35 John Carruthers

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Posted 15 July 2013 - 04:26 AM

Maplin do a 5A 12V camera power supply ...
http://www.maplin.co...ersupply-535932

or I use an old PC psu.






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