Re: [APML]: Byers drive and the MototrakIV

[Mike Regish <mregish@map.com>]

C. J. Klingman wrote:

>
> This thread about the Byers Drive and JMI is not making any sense to
> me.
>
> First of all, you surely must know the type of motors you have on the
> RA
> and Dec axis.

My current drive (an old Meade 1266) has a 120V AC RA motor and a 12V DC
dec motor. I am replacing the RA gear, worm and motor with an 11 5/16
Byers drive.

> If you have AC synchronous on both axis as I do, they
> will be Hurst and clearly marked for 120vac use.

This is a new Byers drive and it has a 12V DC motor (Hurst) that will
not work with the Mototrak IV that I bought recently. I need to put a
120V AC motor in its place.

> You will have good
> photo guide capability but no slew capability;  have to bump the scope
>
> from place to place by hand.  (AC synchronous motors cannot be driven
> more than ~ +/- 30% of 60 hertz and that is pushing it.)  Of course,
> the
> big accurate setting circles will make this much easier.

Slewing is not a problem. Using the drive with my drive corrector is a
problem.

>
>
> If you have stepper motors, you must have stepper motor drive
> circuitry
> appropriate to the motors, and probably will not be integral to the
> drive.  Overall, stepper motors would be best in order to have
> controllable slew, but it will be expensive and difficult to find such
> a
> dual axis controller if you didn't get one (or any documentation) with
>
> the drive/mount.

All I have is the drive...I'm retrofitting it to my Meade mount.

>
>
> I can't imagine a Byers mount with a DC RA motor although it may have
> a
> DC dec motor.

Well, maybe it's something new. My brand new Byers drive has a 12V DC
stepper motor.

>
>
> In any case, a JMI dual axis controller may or may not suit this
> drive.

It doesn't. That's what the whole thread is about.

> The standard JMI controller output is 120vac for a RA synchrounous
> motor, +/- 12vdc for a reversible DC Dec motor.

I already know that. I got the Mototrak to make the Meade 1266 mount
capable of being autoguided with my ST-4. However, the drive is
terrible. Even with subsecond exposures for the ST-4, there is trailing.
It has a 5 1/2" RA gear.

> I don't think you can get one
> with the output for a reversible 120vac synchronous motor as used on
> the
> Dec axis in my Byers mount.
>
> I use an early 1980's vintage Kencor dual axis controller, which, by
> the
> way, interfaced very well to an ST-4.

Are any of these still available in case, for some reason, I can't put a
AC motor on this drive? I'd rather spend $50 on a motor that another
$259 on a new controller, but you never know.

>
>
> C. J. Klingman
> Austin, Texas