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Old 27-12-2009, 05:10 PM
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gary is offline
Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,406
Argo Navis on Takahashi EM200B

Originally Posted by peter andre View Post
Hi, Gary,
I am about to buy a Takahashi EM-200b mount, which is a Non Goto!
I would like to have it converted into a Goto mount.Sending the mount to Takahashi would cost a fortune!! Could you please advise if your Argo Navis will fit my mount succesfully?
Hope you are still in the air to answer my question.
Peter Andre
Hi Peter,

Thanks for the post and Seasons Greetings.

Firstly, it is important to keep in mind that Argo Navis does not directly interface
to servo or stepper motors. Instead, it interfaces to a pair of optical encoders,
one of which is fitted to each of the two primary axes of the mount. As the
RA or Dec axis rotates, the encoders emit electrical pulses which the
Argo Navis keeps track of. Thus, you use your own muscle power in a PUSHTO
configuration to move the scope. Many prefer PUSHTO over GOTO because
of its fast, reliable and quiet operation.

So if you are after a system that can assist you in locating and identifying
objects in a PUSHTO configuration, then an Argo Navis fills these requirements.

We have an encoder mounting solution available for the EM200 but I would
need to check the difference between the original EM200 and the EM200b
that you mentioned. You can find a scanned image of the installation drawing
for the EM200 on our web site here -
If the hubs have similar dimensions and the existing screw holes are at the
same positions with the same threads, then the existing kit will fit. I recommend you
email me at where we can begin a dialog
to determine what the differences, if any, are between the EM200 and EM200b with
respect the relevant dimensions.

From what I understand, the EM200b was mechanically very similar to the EM200
but had a different control panel.

I mentioned earlier that Argo Navis does not directly drive motors. However,
Argo Navis does interface to some third party motor controllers, in particular
the ServoCAT and the Sidereal Technology servo controllers. This then provides
for full slew and track (i.e. GOTO) support. Though these particular motors systems
have been adapted to some equatorial mounts, I am not aware of any users
having ported them to the Takahashi mounts and certainly some substantial
mechanical improvisation would be required.

By comparison, the encoder PUSHTO solution can be installed in less than
20 minutes.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place
Mount Kuring-Gai NSW 2080
Phone +61-2-9457-9049
Fax +61-2-9457-9593

Last edited by gary; 27-12-2009 at 05:25 PM.
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