Limerick Astronomy Club

After constant what could only be called nagging by Franks for 6 months solid , I finally had a look at the following website in October.
http://www.servocat.com/
I deliberately stayed away from that site as I knew once I had a good look I'd just have to go for it. After the WSP this year where someone knocked the scope out of position just before Chris Lintot was going to look through it, I gave in and god help me I'm just a gadget nut and went for it.
I sent Garry Myers (Mr Servocat) some enquiring emails as to how it works and what it can and cant do and found him very informative with no waffle.
So for the first time in about 5 years I bought something that didn't come from astromart.

This is the servocat and argo-navis system which basically makes the 20" obsessionator a GOTO telescope.
Its a high power geared servo motor system (not a stepper motor) which is built as a kit and can be added to almost every production dobsonian/fork mount/equatorial system and many homemade Dob systems out there, although its main market is the large Dob sector.
It is supplied with a DVD showing you how to install it, it requires a fair amount drilling and hole sawing the scopes rocker box base, I did this very slowly as there are sections of it that if you rush it and drill the wrong sized/angled hole or off center you'll make life extremely difficult for yourself, infact if you drill the groundboard attachment hole wrong then you might be goosed completely!!
Here is a pic of all the parts out of the box, I checked everything to make sure it was all there.


The system basically consists of the servocat handpad and controller which controls 2 high power motor/gear system, is linked to a box called an argo-navis which is linked to 2 optical 10,000 step encoders, the argo-navis is akin to the autostar on a meade scope but with alot more features. It has the usual NGC/messier/IC and many more catalogues and you can upload asteroid,comet and satellite files to it + user defined objects. It has an in built mount error correction system called TPAS, similar to Tpoint in "The Sky". It is ASCOM compliant so it will talk to any planetarium program on a laptop/pc using the LX200 protocol, very handy!. It even has a built in dew heater for the LCD display.
Here is the Argo Navis and Servocat control pad


The servocat itself can even use a ST4 for tracking corrections so you could do deepsky imaging with it, of course I'd need a field derotater for this for longer exposures.
The black box on the front of the scope is the ServoCat itself


It took me about 12 hours to put it all together, it seems to work very well, the hushed deep whirl sounds of the motors make the LX200 motors sound like a Honda50, the motors and gear system is all stainless steel and is made to last.
This is the Azimuth motor assembly


and this one shows the altitude motor on the side of the rockerbox and all the cabling needed.


It can drive a much bigger scope, they say beyond a 30+ inch without any modifications, so it drives the 20" effortlessly. It does have a slip mechanism which prevent damage say if your scope got cought up in a strong gust of wind or someone tripped over themselves while looking through the eyepiece.

One really cool feature is the slip return feature, say someone was looking through the eyepiece and pushed the scope so they basically loose the object, all you need do is press a button and the scope will return back to the object, handy for people who tend to be accident prone.
To be honest, from what I've seen of this so far, you'd actually need to fall off the ladder onto the scope itself to move it, its held very rigidly !.

The system turns the scope east/west by driving a silver cylinder against a circular board known as the ground board. The altitude axis is moved by placing a stainless steel cable along the altitude bearing and then wrapping it around a spinel which is driven by a motor.
It has engage/disengage levers on both axis so you can use the scope manually if you want, even if you do, the system still knows where the scope is at all times and will not loose sync as the encoders are not tied to the motor system directly as you might see in practically all other goto scopes.

Power is its sole weakness (only a problem really if you have a bad battery), the motors on full slew draw 4 amps, that 4 times what the LX200 takes, so it will be interesting to see how long the battery lasts on a cold night. I don't mind this really as who would be slewing all night and I'd rather have a very beefy motor system then one teetering on the brink of flying apart!. I got the mains power supply for it also so I intend using that where possible.

I went for the stalk option as I figured I'd want a convenient place for the controllers


I also went for the wireless controller so I could move the scope while looking through the eyepiece without having cables all over the place.
The system is very neat with all of the cables are located in the floor of the rocker box base.

I added a few things of my own such as an onboard voltmeter and now been able to power the primary mirror fan and the secondary mirror dew heater using the same power as the rest of the system, bye bye batteries. I also, put in a 12v power socket on the side of the scope as I might mount the battery pack on the side of the scope to avoid people tripping over the cable. I cant see the weight of the battery pack having any effect on this system.

The real beauty with a system like this is that IF I ever got a bigger Dob, I can take this system off this scope and put it on that, but there is no way I'll be upgrading from this scope unless I win the lottery or something similar..

So,I hope that this has been an interesting read as I haven't seen any mention of a system like this on the boards before.
I'd be happy to answer any questions any of you might have.


BTW, thanks Frank for "persuading" me that this was a great idea, you were dead right, I'm looking forward to seeing you get yours !.


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Hi,
After searching the web to find a better way of carrying around a battery and other bits'n pieces for the scope, I stumbled on this.
http://www.scopereviews.com/dobmod.html
I have to say I thought this guy was mad !! but after sitting down over a hot cup of tea and thought about it a little, his cabinet seemed the way to go because it catered for the scopes battery and carries all the eyepieces/filters/adapters and every other piece of equipment I could think of.

I was transporting a small table, 2 eyepiece cases and a wooden box for the battery, all a complete pain to drag around, the table had to be light weight so it was flimsy, and where does the second case go?? and how do I protect the battery without making it all very heavy.
So after about 30 mins of searching the web I finally found the cabinet he used, its made by Stanley, so I order it, it was 130e delivered to my front door which I think isn't bad considering the size of it, I had it in 3 days. Here is a pic.


Its galvanised steel, its not heavy and has rear wheels and a towing handle so is very easily movable.
Its made up of 3 separate parts stacked and clamped together so it is easy to get into the car.


It 2 middle shelves are pull out and the top lid opens like a toolbox lid, which is what it is. I left the top shelve half in to show the 2 shelves.


I use the top box for the biggie/expensive eyepieces, the shelves are for the filters and normal eyepieces and anything else I think I might need.

So, I loaded the battery into the bottom section which tips out on a hinge, I want to be able to monitor the battery as I go through the night so I got a voltmeter and an ammeter in ebay, the muppet I bought them from didnt supply any wiring instructions nor was responding to my questions so after abit of experimenting and smoke! I got them working, I thought I had blown the voltmeter, but thankfully it seems to have taken my experimentation well. I put in a switch and a 12v cig lighter socket. I went for this type of covered switch so there is no chance of cutting the scopes power by accident.

Power off


Power on


I put alot of insulating tape around the meters to keep moisture/dew out, the displays are not nearly as bright as they look in these pics, In the above pic is shows 12.57v and 00.0 amps.

Here is the battery compartment

Tangled/messy wiring drives me nuts so I tried keeping things here pretty neat, with minimum disruption needed if I need to remove the battery, I insulated the sides and underneath the battery so it will not get too cold in these long nights as cold reduces its effectiveness. Any showing metallic surface of the cabinet is covered with black insulating tape here to help prevent a short incase a wire works its way loose.

So, that's pretty much it, I'd highly recommend going down this route if you want a convenient way of transporting a big battery and alot of equipment. The one major advantage of this is that you are not fumbling with crocodile clamps with the battery on site, so there is no way of getting the polarity wrong, I've seen first hand what reversing polarity on a scope does not my scope thankfully....

Comments, suggestion are welcome !