[billdan (Bill)]

Mesu 200 GEM Review

I believe I'm the first person to own one of these mounts in Australia and there are only a few in the southern hemisphere.

The Mesu 200 Mounts are hand made by Lucas Mesu (Mesu Optics) in Amsterdam and he also configures the mount firmware for your location. He uses TNT Air Freight to have them shipped to Australia and after GST is paid TNT delivers to the door.

For those unfamiliar with this mount, it is a friction feed mount (i.e a small diameter steel pinch roller pressed against an approx 250mm diam steel disk on each axis). By using this technique, gear backlash is eliminated and periodic error is very low. There is no need for East heavy with this mount, just normal balance. This mount has no clutches so balance is important, there are however hooks that can be locked into place when parked to stop any movement.

The mount has a payload capacity of 100Kg (four x C14 OTA's plus change) and utilises two encoders on each axis. The servo motor encoders are 8 million ticks (0.162arcsec resolution) and the axis shaft encoders are 10,000 ticks (2.16arcmin resolution).

The mount can be used at the equator as its latitude range is from 0 to 90 degrees.

It is supplied with a SiTech Mount controller and when you look at the 235 page manual it is very intimidating but Lucas sets everything up so you don't really need the big manual except for reference. A quick setup pdf manual is also emailed and I followed that procedure (what files to download etc).

Its stated pointing accuracy is < 2.5 arc mins with a single star alignment, and this can be further reduced by doing a PointXP star model. Its Goto speed is 8 degrees per sec at max slew.

It has an internal USB to serial converter for PC comm's, and another serial port for focuser/rotator, an ST4 port, plus the hand controller port. SiTech has its own database of stars and objects but most users link up with CdC for goto's and sync etc.

The options I purchased was the ADM Saddle, and the adapter plate, you can also optionally buy this mount dividable, the RA section weighs 15Kg and the DEC section weighs 11Kg, as my Mesu will be permanently in the Obs I chose not to buy this option. I didn't buy any counterweights so I had to make my own.

Sleeving 5kg Olympic plates that cost $10 is a lot less expensive than the commercial 5Kg counterweights at $100 plus freight . However I will probably buy some eventually to make it look nice.

After I received the mount the first step was to get the adapter plate drilled with four countersunk holes and with the EQ6 Tripod two holes drilled and tapped.

I also printed off some plastic sleeves for the weights, 50mm outer diam and 40mm internal diam to slide along the 40mm counterweight shaft.

While Cyclone Debbie was running amok I tested the mount in the laundry to make sure the laptop could control it OK.
When the weather settled down I installed everything in the Obs and started testing under near full moon.

Continued