GTD G53F User manual

Gemini G53F German Equatorial Mount User Manual Ver2.7
Contents
General.................................................................................................................................................1
Technical parameters.......................................................................................................................2
Delivered Parts.................................................................................................................................2
Mount specific Pulsar2 parameters..................................................................................................2
Assembling/Disassembling the two parts.............................................................................................2
Ad usting Polar Elevation and Azimuth...............................................................................................5
Connecting Cables................................................................................................................................6
Using the G53F.....................................................................................................................................9
First time setup.................................................................................................................................9
Making a goto................................................................................................................................10
Absolute Position Reference..........................................................................................................11
Using real time tracking speed correction.....................................................................................12
Practical hints.................................................................................................................................12
Astrophotography with the G53F..................................................................................................13
Remote use of the G53F.....................................................................................................................14
Maintenance.......................................................................................................................................14
General
The G53F is a Friction Drive Telescope Mount, there are no traditional gears used.
This ensures smooth, high precision and backlash free motion in silence. Moving
parts roll on each other which guarantees a long life.
The drive unit consists of a stepper motor, reduction gear Gemini Fluido) and the
drive roller. The drive roller is pushed against the drive disk with the torque limited
lock knob. The gearing has an integrated slip clutch that prevets demage to the
drive roller and the gearing itself.
To ensure high goto precison, encoders are fitted directly to both axes. The
encoders correct any slip that may occur if the slip clutch enters in action or the lock
knobs are opened. If you hear a beep after a goto that indicates a large slip that will
not be corrected for safety reasons – the mount probably has hit something.
Both encoders have an absolute position signal that helps recovering lost
positioning in remote applications. The RA encoder can be used to correct tracking
speed for unguided photography. All cables are routed internally as of 06.2016)
The equatorial head can be separated in two parts for transport and storage.
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Technical parameters
Steppers: NEMA 17, 400 step, 1,5 Amp
Drive disk: D 220 mm, stainless steel
Drive roller: D 6 mm, hardened and coated steel
Encoders: Optical incremental, 72 000 pulse/rev
Weight: 20 kg
Load capacity: 45 kg
Maximum unbalanced torque: 15 Nm 1,5kg at 1m radius)
Elevation range: 20 - 90 deg
Temperature range: -20 to +30
Driver: Pulsar2 http://www.geminitelescope.com/pulsar-goto-controllers/
Slewing precision: cca +/- 30 arcsec
Max slewing speed with Pulsar2. 4 deg/sec
Tracking precision: 2”/5 minutes
Power: 12-18VDC, 3A 1A continuous draw at 12V)
Telescope interface: Losmandy rail or custom
Delivered Parts
Equatorial head with Losmandy adapter, Counterweight shaft 30mm), Pulsar2 driver with
hand controller, cables, cable guide ring. Optional: counterweights, polar finder, tripod,
splitter box for the 12VDC supply on the RA head specify length, number and type of
connectors).
Mount specific Pulsar2 parameters
Non default values only)
Total Red: enter 350, the exact value will be calculated by Pulsar2
Track current: 850mA
GoTo current: 1200mA
Stop current: 400mA or 800 for guided photography
Motor step R/D: 400
Encoders: Mount encoders are fitted answer Yes to Mount encoder RA and DEC,
answer No to Motor encoder RA and DEC)
Resolution: 72 000 both RA and DEC
Rotation: leave as it is, will be defined by Pulsar2
Umod Sp limit user parameters) 990
Ramp user parameters) Ra 1, Dec 2
Backlash user parameters):0 arcsec
There are videos on YouTube to help with the setup and other features. Visit this link to see the
updated list: http://www.geminitelescope.com/gemini-german-fork-mounts-goto-manuals/
G53F manual ver 2.7 p2 June 2017 www.geminitelescope.com
Power supply choice: universal laptop psu, traditional linear transformer +rectifyer), car or solar panel lead
battery are all suitable. Switching PSUs can sometimes create interference and not work properly. IF
YOUR MOTOR DO NOT WORK PROPERLY TOP AND DO NOT CHANGE PARAMETER ! U E A
CAR BATTERY. IF THI DOE NOT OLVE THE PROBLEM CONTACT U FOR ADVICE!!

Assembling/Disassembling the two parts
1 To assemble the G53F Equatorial Head, rotate the RA head into the
approximate position shown below, lock the red lock knob until it emits a click,
and place the DEC head into the saddle as shown below. Attention, it may fall
out of the saddle if left alone in an unsuitably horizontal position!
Make sure the orienting pin in the lower saddle engages the hole in the DEC
head. This ensures the correct contact of the DB9 connector.
2 Next, place the upper saddle on the DEC head as shown below. Find the
position when the bolts enter their relative threaded holes in the lower saddle.
The gaps at the two sides should be approximately equal.
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Lock until you
hear a click

3 Fasten the 4 bolts evenly, changing sides frequently. Fasten them firmly
finally. You will need a 6 mm Allen key hexagonal).
You are ready now. Disassembling is the reverse of assembling.
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Gap on either side
should be approx. equal

Adjusting Polar Elevation and Azimuth
The adjustment range of the elevation screw is cca 20 degrees. If you need
more adjustment you have to reposition the RA head in the elevation plates
as explained below.
1 Remove the DEC head from the RA head. This makes the procedure much
more easy to do.
2 Turn the elevation screw close to the OUT position. when the threaded rod
has most of its length between the two cross rods) This makes the procedure
easier.
3 Remove both elevation locks and the centering rings which are below the
locks. These come out if you release all load on them by turning the mount
head on its side for example.
4 Pull out backwards the RA head from the fork base.
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