Samson EQ mount question.

[GUS.K]

Hi,just joined forum and have a question about the RA drive motor for the old Astro optics samson mount.I do not have the speed control box for it,so can the drive be used stand alone or does it need the controller.Drive is 240 V unit and seems to turn the mount ,but I haven't had a chance to test its tracking ability.Does anybody know what type of controller was used and is there any other option to control the drive.

Thanks

GUS.K

[astro744]

I believe there was a drive corrector available for the Samson and I've probably got the part number in an old Astro-Optical catalogue somewhere. (I will have a look and see if I can find it although you wont be able to buy one new).

The drive corrector would be needed for astro-photography but for general tracking I would think you a fine with just power to the motor.

240V is always a worry and you have to make sure everything is properly earthed. Make sure your 240V supply is protected against earth leakage by a residual current device (RCD) in your power supply circuit. This is now mandatory but old houses do not always have protected circuits. Portable RCD power boards are available. Ask an electrician to check if you are not sure.

[astro744]

In my 1987 Astro-Optical Supplies catalogue under Samson Accessories is listed;

A.O.S. Drive Corrector MkIII ($187.50)

I do not have any other information on this item in this catalogue. I do have catalogues from the late 1970s but cannot locate them at the moment. I thought I had a picture of the drive corrector in one of my catalogues but could be mistaken and if I do find anything I'll post it.

[koputai]

I remember pulling one apart a few years ago.

It used a 555 timer to generate a 50Hz waveform, which could then be varied by a 'Fast' or 'Slow' button, or a pot for fine adjustment.

Electronics Australia magazine did a telescope drive project back in the 80's which I can scan if you need it.

Cheers,
Jason.

[GUS.K]

Thanks guys ,the article would great Jason,and any info on the original drive corrector would be appreciated Astro.

Once again, many thanks.

GUS.K

[torana68]

got a pickie of the mount? Ive only seen one drive corrector sold in the last few years, pretty uncommon now.

[GUS.K]

Hi Roger,I don't have a shot at the moment but will try to take one over the weekend.I use the mount for a 10 inch f6 scope and it can handle the weight well,but never use the drive motor.I originally took the motor off and rigged up some slow motion cables, but now want to set up the drive and want to see if it is possible to find or build a drive corrector for it.

Thanks
GUS.K

[IanW]

I owned a Sampson Mount back in the 70s and it was fitted with the standard RA and dec motor units.

The drive used is a simple variable frequency oscillator (VFO). Plans for VFO's capable of running a telescope are easy enough to find. Just look for a 240Vac VFO drive for synchronous motors. AWR for example in the UK produce such units, it's the model 3 and costs about 245 pounds sterling. see http://www.awrtech.co.uk/

Typically you need about 10-15% frequency variation to cover almost all of the tracking speeds you'll need.

Good luck

[doppler]

Hi Gus, I still use an old cave mount which is similar to the samson mount. The motor drive on its own does a reasonable job at tracking with a well polar aligned scope for short exposures (30 sec). The drive corrector makes this easier and helps to control any periodic errors. My drive corrector is also a power invertor so it runs of a 12v car battery.

[GUS.K]

Thanks Ian for the AWR link,and Rick for the picture of the drive corrector.
Just want to see if its worth the hassle to retrofit this mount or better to buy a new mount.

GUS

[IanW]

Gus, you'll like this link even more..

http://www.oasi.org.uk/ATM/Eq_mount/Eq_mount.shtml

It's got a virtually identical drive corrector. A quick look at it and I reckon it could be built for under 50 bucks including a case. If you know someone handy at electronics it's a weekend project.

[doppler]

My old drive corrector is a backyard job, cheap but still going strong after 25 years. It won't be cheap to buy another mount that will handle a 10" f6 newt like the old sampson.

Rick

[GUS.K]

Thanks Ian,I do know an electronics tech & I think I might give this a go(I am also an electrician and know basic electronics as well) and Rick you are right about the mount ,I probably won't find anything else to handle a 10 inch that will be relatively cheap.

[IanW]

You're welcome, to add correction switches isn't hard, a couple of mods to the circuit to give you a few percent extra frequency and a simple kill switch. Alternatively you could adapt the existing drive to stepper motors or servo motors and that would really open up some interesting possibilities for PEC and robotic control etc.

[doppler]

I would love to upgrade the drive electronics on my old cave mount, it's so solid and easy to use as a basic eq mount.

[IanW]

If you've got access to a machinist it's not difficult. The hard part is getting the stepper or servo motors at a reasonable price and the associated drive electronics. AWR and others supply the parts but it's not cheap probably around $1200 or so all up, however given the quality of the old mounts and their better weight carrying capacity etc it's probably worth serious investigation and thought.

[koputai]

I beg to differ. I used to have an AOS Samson mount, and thought it was
pretty good. Now I have an EQ6Pro, and really they are chalk and cheese.

The EQ6 can take a bigger load, tracks better, and is less wobbly. It also
can take autoguiding input if that's your bag.

IMHO the old mounts are for people who like the quirkiness of older gear,
which is fair enough, but I personally wouldn't go spending anywhere near
$1200 to fix up an old mount when a 2nd hand EQ6 or similar can be had
for much less, and perfoms much better.

Cheers,
Jason.

[GUS.K]

Thanks for the info Ian,this will be a long term project,like Rick said ,these mounts are solid and easy to use and to get a mount to carry a payload of more than 20 kg can be very expensive,I think this mount is a keeper.
Thanks guys.

[GUS.K]

Hi Jason,I got the scope for nothing and find that it works well,it can handle the weight of a 10 inch f6 solid steel tube plus heavy eyepiece without any problem-the only work I did to it was to make a new tube strap harness and to paint it as well.I am looking to try my hand at some astro photography and was looking at getting a drive corrector for it.
Thanks GUS.K

[koputai]

Fair enough Gus.

I found that Electronics Australia article I mentioned earlier. It's not for
syncronous motors unfortunately, but for a stepper setup, so if you were
planning on changing your drive motor to a stepper then it may be useful.

If you want me to scan it, pm me your email address and I'll send it to you.

Cheers,
Jason.

[IanW]

Hi Jason,

Each to their own. An autoguider input costs about $20 to implement on almost any mount, The EQ6 is a nice mount but my experience with it indicates it doesn't handle longer solid tube reflectors very well as it's shaft sizes simply aren't able to deal with the momentum involved. PPEC costs under $100. I must admit that I was underwhelmed by the EQ6 with a 12" F6 attached to it.

[GUS.K]

Thanks Jason, but I will stick with the syncro motor as it works fine so will keep looking for a drive corrector or build one myself.

Thanks.

GUS.K