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vixen porta mount with jmi tnt tracking

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#1 ictus


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Posted 19 May 2013 - 01:30 PM

Hello I have a vixen porta mount and i,am thinking about getting the jmi tnt tracking.does anyone have this set up?
and are you happy with it? Is it worth it? Thanks Anthony :question:

#2 mayidunk


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Posted 19 May 2013 - 03:02 PM

I don't own this item, so what I've written below is based upon my poking around, and not on experience. Feel free to ignore it, as I'm sure if someone has one of these, they'll be commenting on it soon.

Anyway, JMI usually makes good stuff, and this seems to be made for the Porta Mount. The only thing would be your patience with having to continually adjust the tracking speeds, as it appears that the speed adjustments don't self-adjust the speeds of the individual axes as the mount tracks through various parts of the sky. Here's a blurb from ScopeCity's ad for the Train-N-Track for the Vixen Mount:

"The Train-n-Track (TNT) system is a basic alt-az motor drive system with adjustable or trainable tracking. With alt-azimuth mounts, the motor speeds will vary greatly depending on what area of the sky you are viewing. In some situations, the altitude motor will run very fast and the azimuth motor will run very slowly. In other areas of the sky, the opposite will be true. Completely computerized alt-az systems will track automatically in any part of the sky. The TNT, however, requires that you adjust the motor speeds for your position."

Based on this, it appears that JMI's use of the word "train" may mean nothing more than "manually adjust the speed of either axis as the situation warrants it!" And it's also pretty apparent that this isn't adding GOTO capability to whatever mount you add it to.

So, this appears to be nothing more than a costly replacement for the slo-motion knobs you would normally use with a Porta-Mount. Depending on your particular needs, it may be a boon, or it may be a costly burden!

Welcome to Cloudy Nights, and good luck! :D

#3 beatlejuice


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Posted 19 May 2013 - 06:14 PM

I have it with the voyager mount basically the same as the Porta. Although I have had it for a few months it has not gotten the work out that makes me feel truly comfortable with the tracking as I have spent most of my limited observing time with my dob. It does work but takes practice. I have managed to keep something centered for up to 30 sec. and more is possible I am sure if I spend more time at it. It has variable speed functions in both AZ and Alt which you use to 'train' the motors, as well as higher speed slewing. You can also slew the mount manually without any clutches involved. When I have more time in the near future it will be a pleasure to use for visual. As a side note, my 26 year old son who has no interest in astronomy spent 15 min one night cruising over the surface of the moon at 150x with the hand controller.
It is pricey so be prepared to follow the learning curve and spend a good deal of time with it if you decide to get it. Otherwise it will, as was said above, just be a costly (although much better) replacement for slo mo controls.


#4 ictus


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Posted 19 May 2013 - 07:34 PM

Thanks guys if wasn,t so expensive for the same money i could get a full goto mount. anthony

#5 wcstarguy


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Posted 20 May 2013 - 12:06 AM

I recently acquired one of these in used but "as new" condition from A.Mart. It is fitted to my AT Voyager mount and seems like a quality product. I have only had the chance to use it for a couple of short sessions and I think it will work well for me as a visual observer. I have found in my two short sessions that it does take practice to use effectively and I am getting the hang of the device. I don't know that I would have purchased for the full new price but as I got it for about $100 off the new price I am satisfied with it. I agree with everything beatlejuice posted above...wc :jump:

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