Setup Question for ST4 and pre 2005 Mount

[John Dorio]

Setup Question for ST4 and pre 2005 Mount

Hi All,

I have a pre 2005 mount that has a home made drive corrector for the Meade Reasearch Grade mount and I'm trying to use the ST4 port for PHD2 guiding. I built an opto-isolator to buffer the ASI120 Guide camera with the drive corrector hand controller.  I set the PHD2 mount setting to "On Camera" but what should I select for the Aux Mount option? The mount system does not have a controller and I just want to use this ST4 port to guide the telescope. Should I use simulator and will that work for guiding the telescope?

Thanks in advance for your opinion,

John

[wave...@talktalk.net]

Hello John,
I had to Google for 'Meade Research Grade mount' to try and understand your problem. The term seems to have been applied primarily to Meade's earlier optics rather than their mounts, though maybe they did a better made than average mount too (?). Anyway, if you're talking about an LX200 type or something similar, then the issue of pulse guiding has been fixed by the latest ASCOM mount driver from Colin Dawson.
When I first started guiding my LX200 Classic, I also went the ST4 route using a Shoestring ST4 controller with opto-isolators until I realised I was behind the times. Using a standard USB/Serial cable I now guide my Meade through the RS232 serial port. The PHD2 mount selector uses the Meade Generic (ASCOM) driver, so the 'Aux Mount' is not involved.
If this could help with your problem, then the latest Meade driver can be found HERE:

Each driver update is labelled 'Meade.net.Setup' and is a self-extracting/installation file.
After installation, the driver name will appear in the PHD2 dropdown for mount selection.
It's called 'Meade Generic' and provides pulse guiding capability to the early Meades. There's a few settings available in the driver's Properties dropdown, which are pretty obvious. Apparently, Classics don't require any new entries other than the COM port number assigned by Windows to connect it to Stellarium, PHD2, PEMpro, etc
Cheers,
- Jack

[John Dorio]

Thanks for the fast reply and assistance. Well I should have stated that my setup is based on the Meade LX3 system and the replacement drive corrector uses the circuit in Figure 6 of the attached file. I also built an opto-isolator circuit with the ST4 pins compatible with Celestron, Orion, and QHY5 telescope interfaces. See attached. The mount has a 117vac synchronous motor with a 7.5 in Byers gear and the declination motor is 12vdc which drives a directly coupled tangent arm.

I plan to run calibrations before every image. I'm aware that there may be some backlash but I need a starting point where I can have the PHD2 send pulses to the ST4 port to control the telescope.

Thanks in advance for your comments,

John

[bw_m...@earthlink.net]

It sounds like you need to use the most basic setup.  So connect the guide cable from the guide camera to the ST-4 port on the mount, choose ‘On camera’ for the PHD2 mount connection, and leave the ‘aux-mount’ at ‘none’.

 

It’s imperative that you use the new-profile-wizard to set this up and you will need to know the mount guide speed in addition to the guide scope focal length.  With ST-4 guiding, it will almost certainly be 0.5x sidereal.

 

Assuming you can get this going, you can reduce the number of calibrations you have to do to some extent.  Read the User Guide to learn about the ‘Ask-for-coordinates’ aux-mount option and also the ‘Flip calibration now’ function under the Tools menu.  Without doing any of these things, you will need to do a calibration whenever the mount is slewed.

 

Good luck,

Bruce

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[mj.w...@gmail.com]

Hi John

Way back I had a Meade LX6 that I modified to be able to guide.

Driven from a PC via an ASCOM LX200 Emulator to relays wired to the handbox buttons

Change-over relays instead of make-break optocouplers, a LX6 necessity as the handbox buttons were changeover, not make-break.

It too had a tangent arm Dec drive.

To get Calibrations in about 12 steps you may need to play with the Calibration Step size.

And differing RA and Dec Guide Speeds.

Make sure the threaded rod that drives the Dec Tangent arm is well lubricated and not at all hard to turn.

You'll probably have to look up "Uni-Direction Dec Guiding" in the PHD2 Instructions.

Michael

Wiltshire UK