GoTo & Tracking Systems
EQ Mounts
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Older Equatorial Mount Conversions

Due to an increase in the popularity of converting older, heavy duty German Equatorial Mounts, a web page about the conversion process for these types of mounts follows. 

In order to have us complete a conversion for you, we must have the mount here. We can't stress this enough. 

  • The complete conversion of a GEM, with 1.5 - 2" shafts for example, will typically cost between US$1400.00 - US$2500.00.  Options chosen by the customer will alter that base estimate. 
  • Customers who already have some of the needed parts, (laptop, gears, the controller, motors etc.), will be charged less if the parts are suitable. However, we have yet to convert a large GEM for less than US$1400.00. 
  • The total conversion cost depends on the gear ratio you are wanting on the scope. For visual use and short ccd work, a small 180:1 Dec. gear and the stock 180-360:1 R.A. gear will work great. It is a little cheaper too. Long exposure CCD work requires a little more gearing and costs a little more. (the gears cost money and the modifications to hold them in place cost money). This is assuming that you have a good 359/360:1 R.A. gear.
  • Toothed belts and pulleys are required on all conversions to achieve the recommended ticks per revolution.
  • Once converted, your mount, if it is in decent mechanical shape, can easily achieve sub arc second pointing accuracy. This is verified on a recent DS-16 conversion, by the owner. 
  • Astrophotography is easily accomplished using one of the large old GEM's. Periodic error for the gearing we make is typically on the order of 5-6 arc seconds per worm revolution. This is before any autoguiding corrections or P.E. eliminator corrections.
  • The use of ultra expensive gears is not necessary. We typically recommend using our own shop made worm gears. 
  • There is a manual for using GEM's listed in the interactive support page.
  • Slewing speeds will be around 3 degrees per second if you use a 360:1 gear ratio on each axis. The higher the gear ratio, the slower the slew speed. 
  • Since most of these mounts will be in an observatory, we do recommend using a laptop to operate the software. Most observatories are small and an added desktop/monitor will take up more space.
  • Laptops can be bought from E-Bay for $150-$225 daily. Specifications and comments about the laptops can be found on our "About the Computer" page.
  • You can interface scope with any planetarium or camera program that is ASCOM compatible.
  • Mount time away from you will be on the order of 4 weeks. We typically charge you at least half of the total cost up front, order all the parts, get most of it ready for conversion and then get the mount from you for conversion. This way we don't have mounts filling up the shop waiting on parts. You don't loose your mount for very long either.
Do keep in mind that our scope control system is extensive and has been tested and used by hundreds of scope owners of a period of many years. It is not a 'hobbled together' system that will give you problems most of the time and rarely work properly.

When a scope is properly converted, installed and the end user knows how to operate it, it's accuracy and performance will astound even the most critical observer. When you consider what others pay for something that performs only half as well, you truly do get more than you pay for with this system.

Electronics and software by Dan Gray
Conversion design by Lenord Stage
GoTo & Tracking Systems
 5000 Green Hollow Dr.
Arlington Texas 76017-5910
(817) 468-0154