5
ASTRO-PHYSICS
1200 GERMAN EQUATORIAL WITH
GTO SERVO MOTOR DRIVE
MODEL 1200GTO PARTS LIST – MODEL GTOCP3
1
Polar axis assembly (right ascension-R.A.) with Servo Box GTOCP3
1
Declination (Dec.) axis assembly
1
18.5” Stainless counterweight shaft (1.875” dia.) with washer stop and black plastic knob (knob has 5/16 thread)
1
Y cable – R.A. portion is 12.5” long and Dec portion is 37.5” long
1
D.C. power cord (cigarette lighter adapter on one end) - 8’ long
1
GTO Keypad controller with 15’ coiled cable
1
Keypad Protector (KEYPRO)
1
Hex key set
2
8-32 thumbscrews (substitute these for 8-32 set screws that hold GTO Servo Control Box in place, if you wish)
1
PulseGuide software by Sirius-Imaging on CD
In order to fully assemble your mount, you will need the following items sold separately: pier adapter (either standard or
rotating), mounting plate, 10” O.D. pier, counterweights and portable rechargeable battery pack (or 110 to 12V DC
converter). Several sizes and types are available for your selection. Many of these items will be discussed throughout
these instructions.
Several additional options are available:
28” counterweight shaft – 27” useable length, part # M12661-A
Santa Barbara Instrument Group CCD Imaging cameras and ST-4 Autoguider or STV - if you plan to pursue CCD
imaging or astrophotography
Pier accessory trays for 10” pier and support bars - handy to keep your eyepieces close at hand
Polar axis telescope - threads into the base of the polar axis assembly. Many users find a polar axis telescope useful for
zeroing in on the pole quickly, particularly with telescopes that are not orthogonal to the mount.
Mounted encoders – Although you can use these with your mount, they are not necessary since the go-to functions of
the mount are more accurate. The 4000 steps of the encoders, which read the position of the shaft are very
coarse (324 arc seconds) while the encoder that is built into the servo motor itself is 0.05 arc seconds.
FEATURES AND SPECIFICATIONS
R.A. worm wheel:
10.3”, 225-tooth aluminum
Dec worm wheel:
7.2”, 225-tooth aluminum
Worm gear:
Brass
R.A. shaft:
3.35” diameter
R.A. thrust bearings:
9.5” diameter
Dec shaft:
2.36” diameter
Dec thrust bearings:
6.5” diameter
Counterweight shaft: 18.5” useable length, 1.875” diameter, stainless steel, removable
Latitude range:
21.5 - 68 degrees with or without
polar scope or encoders attached
Azimuth adjustment:
Approximately 14 degrees
Setting circles:
Porter Slip Ring design, engraved
Right ascension:
4-minute increments, pointer
Declination:
1-degree increments, pointer
Motors:
Zero-cogging servo motors
Power Consumption: 0.4 amps at the sidereal rate
3 amps both motors slewing
Power requirements: 12 VDC, range 11.5 to 18V (higher voltage recommended for very cold temps and heavy loads)
Weight of mount:
Equatorial head:
81 lbs. (36.7 kg)
Dec axis:
31 lbs. (14.1 kg)
R.A axis:
50 lbs. (22.7 kg)
Counterweight shaft:
14 lbs. (6.4 kg)
Summary of Contents for GTOCP3
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