1100GTO German Equatorial Mount with
GTOCP4 Servo Motor Drive

Mounts Shipped
Starting in
September 2022

Keypad Optional

Astro-Physics, Inc.

11250 Forest Hills Road
Machesney Park, IL 61115
Telephone: 815-282-1513
Fax: 815-282-9847
support@astro-physics.com
www.astro-physics.com

ASTRO-PHYSICS

1100GTO, 1100GTO-AE and 1100GTO-AEL GERMAN EQUATORIAL
MOUNTS with GTOCP4 SERVO MOTOR DRIVE
1100GTO PARTS LIST

4

1100GTO-AE PARTS LIST

4

1100GTO-AEL PARTS LIST

4

RECOMMENDED AND OPTIONAL ACCESSORIES5MECHANICAL SPECIFICATIONS

6INTRODUCTION

7

Why Polar Alignment is Important

7

ASSEMBLY DIAGRAMS

81100GTO Assembly Diagram

8

1100GTO-AE or -AEL ASSEMBLY Diagram

9

Handy Tools to Have on Hand

10

WHAT IS MEANT BY “INITIALIZATION”?

10

QUICK START SUMMARY – NEW INSTALLATIONS using Keypads

11

QUICK START SUMMARY – NEW INSTALLATIONS using Computers

12

AT YOUR OBSERVING SITE

13

Assemble Pier (purchased separately)

13

Attach Polar Axis Assembly to Pier

13

Latitude Adjustment for 1100GTO German Equatorial Mounts
Special 90 Degree Alt-Azimuth Position

14
15

ASSEMBLY INSTRUCTIONS

16

Understanding Cabling Differences in Non-AE and AE Mounts
1100GTO
1100GTO-AE / AEL

ASSEMBLY OF R.A. AND DEC. AXES

16
16
16

17

Assembly Procedure

17

Disassembly procedure

18

CABLE MANAGEMENT

19

Preparation

19

The Basics

19

The Specifics
Routing Cables if You Plan to Use the Cable Router When Using the Polar Scope
Routing Cables if You Don’t Plan to Use the Cable Router

19
20
21

ATTACH MOUNTING PLATE

22

Fixed Mounting Plate Options

22

Losmandy D-Style Compatible Saddle Plates

23

Side-by-Side and Vixen Style Plate Options

24

ATTACH COUNTERWEIGHT SHAFT AND COUNTERWEIGHTS

25

ATTACH MOUNTING RINGS AND SCOPE

25
1

UNDERSTANDING THE R.A. AND DEC. CLUTCH KNOBS

26

BALANCING THE TELESCOPE

27

Preliminary Balancing

27

Precision Balancing

27

BALANCING SIDE-BY-SIDE

29

ALTITUDE AND AZIMUTH ADJUSTMENTS – ROUGH POLAR ALIGNMENT

31

POLAR ALIGNMENT OPTIONS – FINE POLAR ALIGNMENT

32

Methods for fine polar alignment

32

Making Precise Altitude and Azimuth Adjustments
Fine Altitude Adjustment
Tips for Adjusting the Altitude
Fine Azimuth Adjustment
Precision-Adjust Rotating Pier Base with Azimuth Bearing

33
33
33
34
34

Using Software to Improve Pointing Accuracy

34

MISCELLANEOUS ITEMS

35

Lanyard Post and Bubble Level

35

Warning for Dec. Servo Cable

35

SLEWING YOUR MOUNT IN BELOW FREEZING TEMPERATURES

35

ORTHOGONALITY CORRECTION

36

1100GTO-AE AND 1100GTO-AEL ABSOLUTE ENCODERS37

QUICK START SUMMARY – NEW INSTALLATIONS USING KEYPADS39

QUICK START SUMMARY – NEW INSTALLATIONS USING COMPUTERS

40

AUTO-ADJUSTING GEARBOX - NO MORE WORM MESHING!

42

Additional Parts Included with the Absolute Encoders
Absolute Encoder Cable Connections
Benefits of Absolute Encoders Summary

Checking and Adjusting the Gearbox Backstops in R.A. and Dec.
What to do if you believe that there is a backlash in the gearbox

SOME IMPORTANT NOTES

37
37
37

42
43

44

MOUNT CARE, CLEANING AND MAINTENANCE

45

Care

45

Cleaning and Touch-up

45

Counterweight Appearance

45

Routine Mount Maintenance45

Worm Wheel Maintenance45

Greasing Mount

46

TROUBLESHOOTING, TIPS AND SUPPORT

46

Troubleshooting and Tips

46

Additional Support

49

APPENDIX A: DECLINATION AXIS BACKLASH TESTS
2

50

PulseGuide™
Dec Backlash Test 1
Dec Backlash Test 2
After Running Tests 1 and 2
Dec Backlash Test 3

50
50
50
51
51

MaxImDL™
Step 1
Step 2
Step 3

51
51
51
51

APPENDIX B: MOUNTING PLATE FASTENER CHART

Please Record the Following Information for Future Reference
Mount Serial Number:_____________________________________________

GTOCP4 Serial Number:_____________________________________________

Keypad Serial Number:_____________________________________________

Purchase Date:_____________________________________________

352

1100GTO PARTS LIST
1
Polar Fork / Right Ascension Axis (R.A.) Assembly
1
Declination Axis (Dec.) Assembly
1
GTO Servo Control Box (GTOCP4)
1
GTOCP4 Control Box Adapter (M11010) and (2) 8-35 x 3/8” Thumbscrews
1
16.675” x 1.875” Stainless Counterweight Shaft (M9404-B) with machined Safety Stop (M12676)
1
R.A. Cable Router Insert (M11039)
1
R.A. / Dec. Y-Cable (S1100GYCR)
1
D.C. power cord set - 6’ cable with power pole connectors (CABPP6), 18” cable with cigarette plug (CABPP18C) and 				
18” cable with ring connectors (CABPP18R) and clip (FPCLIP)
1
15’ Straight-through Serial Cable (CABSER15)
1
Hex key Set
2
SS Lanyard Posts (cannot ship on mount due to packing)10 3/4” x 8” Velcro Cable tie wraps
1
USB Flash Drive containing: APCC Standard, PEMPro™ v3 Software and PDF of Instruction manuals
Instruction Manuals and Registration Card
Fasteners:		(4) 1/4-20 x 5/8” SHCS (for safety backup of dovetails)		(7) 5/16-18 x 5/8” SBHCS (pier adapter) (6 + 1 extra)		(7) 5/16” flat washers (pier adapter)		(2) 8-32 x 1/2” SBHC (control box adapter lockdown)		(2) 0.187” Shoulder bolt (option for control box adapter attachment)

1100GTO-AE PARTS LIST
1
1
1
1
1

All items listed above for the 1100GTO (except Y-cable), plus:
R.A. and Dec. Absolute Encoders, installed
R.A. and Dec. Readheads with wire harnesses, standard temperature version, installed
Junction Box and X-cables (attached to mount)
USB Flash Drive with APCC Pro
Screwdriver, 1/8” flat

1100GTO-AEL PARTS LIST
All items listed above for the 1100GTO-AE, except that the Readheads are the Extended Temperature Version.

4

RECOMMENDED AND OPTIONAL ACCESSORIESIn order to fully assemble your mount, you will need some of the following items sold separately. Many of these
items will be discussed throughout these instructions.

Recommended Accessories●

8” Astro-Physics Pier: Astro-Physics has several heights and styles to choose from.
Options: 8” Advanced Telescope Systems (ATS) portable pier with 119FSA-FP adapter or Losmandy Folding HeavyDuty Tripod (LMFHDT-AP)●

Counterweights: 5 lb. (5SCWT), 10 lb. (10SCWT), 18 lb. (18SCWT) and 30 lb. (30SCWT188) are available.

●

Regulated Power Supply (AC to DC converter): We offer two choices: 13.8-volt, 5-amp supply (PS138V5A) or
Variable-volt, 25-amp supply (PSVPW25A). Both supplies are filtered and regulated. We recommend the Variable-volt
supply for heavier loads and colder weather. The mount should have its own power supply.

●

Portable rechargeable 12-volt battery pack: Several sizes and types are available from a variety of vendors.
Be sure that your battery pack can supply adequate power for an entire observing session! Please refer to power
requirements under Features and Specifications on next page. We recommend having separate batteries – one forthe mount and one or more for all other accessories: camera, computer, dew removers etc. You may wish to consider:○

CP4 Powerpoles to Alligator Clips (CABPPAL) - For connecting the CP4 Power Cable to battery terminals.

○

DC In-line Watt Meter and Power Analyzer (CABPPWM) - To monitor your power consumption.

Optional Accessories●

Optional GTO Keypad controller with 15’ coiled cable. Hand-held computer to operate the mount without a PC andadditional software.

●9” Counterweight Shaft Extension (M12675): For heavier loads.

●

Autoguiding accessories: Various guiding configurations can take advantage of the 1100GTO’s autoguider port.
The autoguider port receptacle (RJ-11-6) uses the industry standard SBIG ST-4 wiring setup.

●

Pier accessory trays and support bars: Accessory Tray (TRAY08) and/or Eyepiece Accessory Trays (TRAY08H)
with Bi-Level (TRAYSB) or Single Level (TRAYSB1) Support Bars. Keep things close at hand.

●1100 Flat Surface Adapter (119FSA): For attaching the 1100GTO to your own custom pier or tripod.

●

1100 Flat Surface Adapter with Flat Pier Plate (119FSA-FP): For attaching the 1100GTO to the Advanced
Telescope System (ATS) pier, or to your own custom pier or tripod when a flat pier plate is needed.

●

Polar Alignment Scopes: AP Right-Angle Polar Alignment Scope (RAPAS) and Losmandy Polar Alignment Scope(PASILL4-179) – Many users find a polar alignment scope useful for zeroing in on the pole quickly. This is particularly
important when using portable setups.

5

MECHANICAL SPECIFICATIONS
Construction

All CNC machined aluminum bar stock, stainless steel, brass; stainless steel fasteners

Finishing and Assembly

Every part is hand-finished and inspected. All assembly is done by hand, by highly skilled
mount assembly staff.

Worm wheel - R.A. & DEC. 7.2” (183 mm), 225 tooth aluminum
Worm gear - R.A. & Dec.

0.71” (18 mm) diameter, special low-wear alloy

Axis shaft - R.A. & Dec.

3.15” (80 mm) diameter

Shaft axis bearings - R.A.
& Dec.

3.94” (100 mm) diameter

Latitude range

0 to 78 degrees and 90 degrees for Alt-Az

Azimuth adjustment

Approximately 18 degrees (+/- 9 degrees from center)

Counterweight shaft

1.875” (47.6 mm) diameter x 16.675” (424 mm) usable length, includes large machinedsafety stop knob; weight: 12.9 lb. (5.8 kg). Optional shaft extension available.

Weight of mount

R.A. axis / polar fork: 27.6 lb. (12.5 kg)
Dec. axis: 15.6 lb. (7.1 kg)
Dec. top plate 1.5 lb. (0.7 kg)

Capacity of mount

Approximately 110 lb. (50 kg) scope and accessories (not including counterweights),
depending on length. Recommended for refractors up to 200 mm, 14-16” Cassegrains,
Ritchey-Chrétiens and CDKs.
These are only guidelines. Some telescopes are very long for their weight or heavy for
their size and will require a larger mount. Remember also that imaging requirements are
more rigid than visual observation.

Instrument mounting
interface

Reference the “Attach Mounting Plate” section of the manual.

Pier adapter base7.730” (196.3 mm) diameter. The base is an integral part of the mount and azimuth
adjuster.

For a complete listing of the servo control, power, and periodic error specifications, please see the
GTO Servo Drive System Manual.

6INTRODUCTION

The 1100 German equatorial was designed to meet the needs of the advanced observer who requires a mount withmaximum strength and rigidity and minimum weight. The excess material in both axes has been carved out while retaininga heavily ribbed structure for internal strength and rigidity. A unique dovetail was machined into the mating surfaces of
the R.A. and Dec. axes and also between the Dec. axis and the Dec. axis Top Plate. This feature allows quick and easy
assembly in the field without any tools.
The DC servo motor drive with GTO computer system, the optional keypad with its digital display screen, and the included
AP V2 ASCOM Driver and PEMPro™ v.3.x software all combine to offer extraordinary sophistication for today’s observer.
Whether you enjoy visual astronomy exclusively or plan an aggressive astrophotography or CCD imaging program, thismount will allow you to maximize your night out under the stars.
The advanced keypad features allow you to slew automatically to objects in a wide range of databases as well as any R.A./
Dec. or Alt./Az. coordinate. A large selection of common names for stars and other objects makes your selection a snap.
The rapid slew rate of 5 degrees per second (1200x) allows you to locate objects very quickly and accurately. You will bevery pleased with the intuitive operation of this keypad. There are no complicated sequences of keystrokes to remember.
It is so easy to use that even if you don’t use it for a few months, you will feel at home with the keypad very quickly.
The keypad is only one way of controlling the versatile Astro-Physics GTO Servo System. From its very conception, theservo controller was designed to work with any software that was written to use our published command set. We do notlock you into any proprietary software or mandatory “additional” equipment. To increase the versatility of all our mounts,
we have developed and fully support a V2 ASCOM Driver for use with all ASCOM client software.
As mentioned above, we also include a full version of PEMPro™ (Periodic Error Management Professional) v.3.x (latest
version) for you to enhance your control and performance options. As an added bonus, all 1100GTO mounts will comepre-loaded with the custom-fitted PEMPro™ corrections from our extensive individual testing that is performed on each andevery mount. While the native peak-to-peak periodic error of your 1100GTO will be 7 arcseconds or less, you can reduce
it even further to maximize performance without auto-guiding. These software control products are detailed later in the
manual.
In addition to everything outlined above, the 1100GTO’s control and performance options will be greatly enhanced by
the Astro-Physics Command Center (APCC). APCC fully addresses all the capabilities of the 1100GTO, and adds
enhancements not currently available in the keypad or in any other software.

Northern
Hemisphere

or
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7HorizonEq

If you were to take a long exposure photograph with Polaris(often called the north star) in the center of the field, you
would discover that all stars seem to revolve around
Polaris. This effect is due to the rotation of the earth on
its axis. Motor-driven equatorial mounts were designed tocompensate for the earth’s rotation by moving the telescopeat the same rate and opposite to the earth’s rotation. Whenthe polar axis of the telescope is pointed at the celestial pole
(polar aligned) as shown in the diagram at right, the mountwill follow (track) the motions of the sun, moon, planets andstars. As a result, the object that you are observing willappear motionless as you observe through the eyepiece ortake astrophotos.

dePolar alignment permits accurate R.A. movement in order tocompensate for the Earth’s rotation.

t it uLa

Why Polar Alignment is ImportantDth ireN e C ctioor e nth le oPo sti f
le al

ou

n
’s io
nt tatou ro
M ternC

In order to maximize your pleasure on your first night out, werecommend that you familiarize yourself with the assemblyand basic operation of the mount indoors. The temperature
will be comfortable, the mosquitoes at bay, and you’ll haveenough light to see the illustrations and read the manual.
Please take particular note of counterbalancing, use of the
clutches and operation of the keypad controller.

D
th irece
Po tionla ofrAD
th irec xis
N e C tioor e nth le oPo sti f
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The 1100 is equally at home in a permanent observatory or as a portable mounting for remote star parties thanks to theease with which the two axes come apart. This is the perfectmount for a mid-size refractor, Newtonian, Cassegrain or
Zenithastrograph.

EarthASSEMBLY DIAGRAMS
1100GTO Assembly Diagram
The following terms and abbreviations are used interchangeably in these instructions:
Polar axis = right ascension axis = R.A. axis = R.A. housing
Declination axis = Dec. axis = Dec. housing
Please read all instructions before attempting to set up your 1100GTO mount. The model 1100GTO is very rugged;
however, like any precision instrument, it can be damaged by improper handling. Please refer to the diagram below
for an illustration of the mount. The parts are labelled so that we can establish common terminology. Pay particularattention to the section regarding joining and separating the R.A. and Dec. axes, as this is unique to this mount. It is
important to note the need to connect and disconnect the Dec. motor servo cable when doing so.
Dec. Top Plate
Declination
Motor/Gearbox

Clutch Knobs(3 each axis)

Dec. Top Plate
Lock Knobs (2)SafetyScrew (2)Dec. Sighthole
Cover

R.A. Motor/
GearboxDeclination
Axis Housing
Declination
Counterweight
Adapter

Cable
Channel (2)Absolute
Encoder
Read Head
Cover

Safety Screw (2)Dec. Cable
Port Cover

Delrin Washer

Polar Axis
Lock Knobs (4)(hidden)Counterweight
Shaft

R.A. Axis
Housing

R.A. Sight
Hole CoverDec. Lock
Knob (2)Polar Axis
Pivot Bolt

Cable AccessCovers (2)Altitude
Adjuster Knob
LanyardPost (2)Polar Fork
Assembly

AzimuthAdjuster

Safety Stop
GTOCP4 Control
Box & Adapter

Mounting Bolts for GTOCP4
Control Box Adapter (2)(8-32 Shoulder Bolts or 8-32 Button Head Screws)

GTOCP4Control Box Adapter
located behind CP4Control Box
Removal ThumbScrews (2)81100GTO-AE or -AEL ASSEMBLY Diagram
The following terms and abbreviations are used interchangeably in these instructions:
Polar axis = right ascension axis = R.A. axis = R.A. housing
Declination axis = Dec. axis = Dec. housing
Please read all instructions before attempting to set up your 1100GTO mount. The model 1100GTO is very rugged;
however, like any precision instrument, it can be damaged by improper handling. Please refer to the diagram below
for an illustration of the mount. The parts are labelled so that we can establish common terminology. Pay particularattention to the section regarding joining and separating the R.A. and Dec. axes, as this is unique to this mount. It is
important to note the need to connect and disconnect the Dec. motor servo cable when doing so.
Dec. Top Plate

Clutch Knobs(3 each axis)

Declination
Motor/Gearbox

Dec. Top Plate
Lock Knobs (2)SafetyScrew (2)
R.A. Motor/
GearboxDec. Sighthole
Cover
Declination
Axis Housing

Cable
Channel (2)Safety Screw (2)Absolute
Encoder
Read Heads
Dec./R.A.

Dec. Cable
Port Cover

Declination
Counterweight
Adapter
Delrin Washer

R.A. Axis
Housing

Polar Axis
Lock Knobs (4)(hidden)Counterweight
Shaft

R.A. Sight
Hole CoverDec. Lock
Knob (2)Polar Axis
Pivot Bolt

Cable AccessCovers (2)Altitude
Adjuster Knob

Polar Fork
Assembly

LanyardPost (2)AzimuthAdjuster

Safety Stop
GTOCP4Control Box & Adapter

1100GTO-AE & 1100GTO-AEL
Junction Box

Mounting Bolts for GTOCP4
Control Box Adapter (2)(8-32 Shoulder Bolts or 8-32 Button Head Screws)

GTOCP4 (showing AE Cable)

Protective
Insertfor
Encoder
Ring
Control Box Adapter
located behind CP4

Dec. Axis with Absolute Encoder

9

Control Box Removal
Thumb Screws (2)Handy Tools to Have on Hand
In Your Accessory or Tool Box:●

Small torpedo level to level your scope when using the handy reference park positions, particularly during the daytime
polar alignment routine outlined in your Keypad manual.

●Compass - Don’t forget to know your magnetic offset when using a compass (there can be a large difference).

On Your Smart Phone:
For the upmost of convenience, the following items can be downloaded to your smart phone, which you are likely carry withyou everywhere.
●

APP(s) that allow your phone to be used as a level, inclinometer and compass. Don’t forget to know your magnetic
offset when using a compass since there can be a large difference.

●

Astro-Physics Polar Alignment app – The latitude and longitude of your current site will display. APPs are available foriOS, Android and Windows.

WHAT IS MEANT BY “INITIALIZATION”?

In simplest terms, “initialization” is the process of giving the mount’s servo controller the information that it needs to know:○

Where is it?

○

What is the time?

○

How is it supposed to operate?

○

It then unparks the mount and allows you to calibrate the pointing by using a defined AP park position (ifneeded).

The above is the information you entered into your software when you first installed and set it up. For keypad users, it is
the information you entered when you followed the “First Session with your Keypad” instructions (in the Keypad manual).
These four points are detailed below.
1. Latitude and longitude coordinates tell the mount where it is. The GTOCP4 will remember where it was when last powered down, but can’t know if you have moved to a new location unless it is told.
2. Time, date and time zone give the mount the necessary time information. Time information is required to calculate themount’s current pointing position if it hasn’t been moved, and it is needed to calculate the meridian and the horizons.
The mount’s servo does not have an internal battery to maintain time between power-ups, so time is an essential partof every initialization.
3. Commands to establish the tracking, guiding, centering and slew rates along with other similar parameters like PEM tell
the mount how it should operate.
4. The command to “unpark” the mount is sent. This command both ends the parked state and it also calculates themount’s current pointing position if the mount has not been moved manually by hand via loosening the clutches. The
decision whether or not to calibrate on a defined AP park position will depend on the circumstances.
For an established setup that has not been moved, do NOT calibrate on a park position. Resume from last parked orlast position. The unpark command will have resulted in extremely accurate calculation of the current pointing position
without further calibration being necessary.
For new setups, or if you have moved the mount with the clutches, you will need to calibrate on (aka “resume from”) an
AP defined park position.

10

QUICK START SUMMARY – NEW INSTALLATIONS using Keypads
This summary gives an outline of the workflow to have a successful first observing session. Enjoy!
1. Enter the Time and Location data into the Keypad. Follow the instructions in the Keypad Manual for entering your Timeand Location data into the Keypad. (Location 1 is usually your primary observing location)
2. Set the Keypad to AutoConnect: NO. This will allow you to choose the location for which you entered the data above.
Remember to power cycle the mount after the data has been entered. This will lock the information.
3. Assemble the mount. Reference your Mount Manual.
4. Balance the system. Reference your Mount Manual.
5. Polar align the mount – at least roughly. (If using the daytime routine, move this step to after the mount is initialized. If
using the RAPAS, do it before initializing.)
6. Place the system into a pre-defined AP Park position for initialization. Reference the positions shown at the end of thisQuick Start Guide.
7. Power up the mount; select your location and press GoTo.
8. The next menu has 4 choices. Choose “4=New Setup” and select the Park position that you chose in #6 above. This
will initialize the mount and ready it for going to your first object.
9. When you arrive at your first object you may need to use the N S E W buttons to center the object. Do so and thenpress the RA DEC REV button on the bottom right, followed by the #9 button to do a ReCal of position. The following
GoTo slews to other objects should be more accurate.
10. After finishing your night’s observing (or day’s solar observing) it is best to park the mount into your chosen Park position by pressing 2=Setup; then 4=Park / Mount Opt.; and finally choosing the Park position number where you wish topark.
11. Power down the mount.

Helpful Hints●“New Setup” is only used when you are setting up the mount for the first time or if you have readjusted scope position
via the clutches and wish to restart from a “Reference Position”.

●“ResumeLastPosition” is used when you parked the mount at the end of the previous session and wish to begin a newnight of observing. Selecting it will initialize the mount and you’ll be ready to go to your first object.

●

If you are in a permanent setup, then you should set the Keypad to “AutoConnect: YES” so that when you power up
the mount, it will automatically be initialized and ready to go to your first object. This is the most automated of the
setups using the Keypad.

What If I Get Lost?
Hope is not gone...there is a very quick and easy fix!
1. Loosen all the R.A. and Dec. clutches so that the scope can be moved freely with your hands. Moving the scope into a
Park 3 position will provide additional safety for this procedure.
2. Command the mount to go to Park 3 using either the Keypad or a computer (whichever you have been using for theevening). While the motors are moving, hold the scope with your hands so that it remains safe.
3. When the motors both stop, use your hands and put the scope into Park 3 (use your eyes to get close) and then tighten
all the clutches.
4. That’s it...you’re done! Orientation has been restored to the universe! When you go to your first object you’ll need to
tweak the centering and do a ReCal, but you’ll be close.

11

QUICK START SUMMARY – NEW INSTALLATIONS using Computers
This summary gives an outline of the workflow to have a successful first observing session. Enjoy!
1. Install and set up your control software and drivers. For all but the AP GTO Keypad, this can be done before you eventake delivery of your mount.
a) Set up ASCOM and the drivers firsti)

ASCOM Platform 6.3 (currently) - ascom-standards.orgii) AP V2 ASCOM driver - http://www.gralak.com/apdriveriii) FTDI driver - http://www.ftdichip.com/Drivers/VCP.htm See location of driver:
http://www.astro-physics.com/products/accessories/software/Serial_USB/FTDI_driver_find4.pdfb) Install third party software (Starry Night, TheSkyX, MaxImDL, etc.)c) Adjust software settings - follow the appropriate Workflow documentation that follows in this guided) If using the Keypad along with a computer, set the Keypad to AutoConnect=EXT and power cycle the mount inorder to lock in the change.
2. Assemble the mount. Reference your Mount Manual.
3. Balance the system. Reference your Mount Manual.
4. Polar align the mount – at least roughly. (If using the daytime routine, move this step to after the mount is initialized. If
using the RAPAS, do it before initializing.)
5. Place the system into a pre-defined AP Park position for initialization. Reference the positions shown at the end of thisQuick Start Guide.
6. Power up the mount and connect with your primary control software. Use the primary control software to initialize
the mount. Start out from the park position chosen in #5 above. Your other initialization settings will have been set
already in step #1.
a) If using APCC, always start it and connect with it first.
b) If the AP V2 Driver is your primary control software, it must be started with a client program.
7. Connect other software that you will use with the mount.
8. After finishing your night’s observing (or day’s solar observing) it is best to park the mount into your chosen Park position using either the AP V2 driver or APCC, rather than Third Party software if you are using a PC for mount control.
9. Power down the mount.

What If I Get Lost?
Hope is not gone...there is a very quick and easy fix!
1. Loosen all the R.A. and Dec. clutches so that the scope can be moved freely with your hands. Moving the scope into a
Park 3 position will provide additional safety for this procedure.
2. Command the mount to go to Park 3 using either the Keypad or a computer (whichever you have been using for theevening). While the motors are moving, hold the scope with your hands so that it remains safe.
3. When the motors both stop, use your hands and put the scope into Park 3 (use your eyes to get close) and then tighten
all the clutches.
4. That’s it...you’re done! Orientation has been restored to the universe! When you go to your first object you’ll need to
tweak the centering and do a ReCal, but you’ll be close.

12

AT YOUR OBSERVING SITE
Assemble Pier (purchased separately)
Begin by assembling the portable pier at the desired observing
location. Take note which direction is north. (These instructions
are for the Astro-Physics Portable Piers. For other piers, please
follow the manufacturer’s instructions.)
1. Slide the three legs onto the nubs of the base and rotate
the assembly so that one of the legs points toward north (ortoward the south if in the southern hemisphere).
2. Place the pier post on the base, orienting the eyelets for attaching the turnbuckles directly above each leg.
3. Attach the tension rods. The turnbuckles should be drawn
tight until the whole assembly is stiff enough to support yourweight without movement.

Attach Polar Axis Assembly to Pier
In order to track the motion of astronomical objects, the Polar Axis must be positioned so that an imaginary line drawn
through the center of the axis points toward the celestial pole. Refer to the diagram at the front of this manual for agraphical representation. At this stage, you want to position the pier so that it points roughly north.
1. Prior to mounting the Polar Axis. Adjust the Azimuth Adjuster so that the Azimuth Adjuster Block iscentered. This will allow adjustability when it comestime to polar align the mount. See photo below.

Azimuth Threaded
Push Rodhut

2. Orient the pier. Set up your pier so that the counterweight shaft is oriented above the north pier leg. It is
important when using a portable pier to face one leg tothe north so that the offset weight of the counterweightshaft and counterweights do not create an unstablebalance.

im
Az

k

oc

Bl

Azimuth Adjuster Knobs

3. Set the R.A. Axis in place. Carefully set the 1100GTO Right Ascension Axis / Polar Fork assembly into the open topof your pier, or into the 1100 Flat Surface Adapter (119FSA), if are using one.
4. Line up the Pier base. If the side thru-holes in the pier or 119FSA are not perfectly lined up with the tapped holes in
the mount’s Pier Adapter base, rotate the mount. Be sure that the tips of the two azimuth adjuster knobs are tightenedagainst the azimuth adjuster block; otherwise, the base will rotate making it difficult to line up the holes.
5. Secure the R.A. Axis to the pier. When you have the holes lined up, fasten the mount to the pier top or to the Flat
Surface Adapter using six 5/16-18 X 5/8” socket button head cap screws and 5/16 flat washers. Note that the washers
have a sharp edged side and a softly rounded side. Be sure that the rounded side faces the paint or anodizing of thepier so that no marring of the finish occurs. Be sure to start all six cap screws (with their washers) before tightening
any of them. Then, snug all six cap screws down before finally tightening them all securely.
6. Level the mount. Although it is not important that a German equatorial mount be level to achieve polar alignment, it
does make it easier in that an adjustment to altitude or azimuth affects only the direction to which you are making theadjustment. If the mount is not level, you will be able to achieve alignment, but when you make an adjustment to azimuth, for example, you are actually making a simultaneous adjustment to both azimuth and altitude when out of level.
Note that if you are using the Right-Angle Polar Scope, it is required to be level in the east-west direction in order toachieve accurate polar alignment. Level the mount...you’ll be ahead in the game!
7. Screw the two lanyard posts into place. These were not installed prior to shipping due to packaging restrictions.
Please reference the prior assembly diagrams for part identification and placement.

13

Latitude Adjustment for 1100GTO German Equatorial Mounts
The 1100 mount accommodates a latitude range from 0 to 78 degrees and 90 degrees. The Altitude Adjuster Bar allows
for gross latitude ranges, while the Adjustment Knob is used to provide the precision adjustments when polar aligning. The
Altitude Adjuster Bar is positioned into one of nine slots which provide an overlapping latitude range.
This altitude bar is very convenient when travelling to remote sites, as it allows you to transport your mount in the morecompact, zero-latitude position. You can change to your remote site’s latitude in one quick motion of the altitude bar.
How to change the position of the Altitude Adjuster Bar

Polar Axis
Lock
Knobs

1. Due to the portable size of the 1100GTO mount, thisprocedure can be done with the mount fully assembled, or can be made easier using only the R.A. axis.
However, DO NOT attempt to make these adjustments with an instrument or counterweights mounted.

Altitude
AdjusterBar

2. The mount’s Polar Axis is held in place between thetwo side plates of the Polar Fork. The axis pivots oncustom shoulder bolts located towards the rear ofeach side plate. These bolts should not be loosened
when making altitude changes to the mount.

Altitude
AdjusterPosition
Slots (9)3. Loosen all four Polar Axis Lock Knobs about 1 turn.
4. Tilt the R.A. axis upwards and hand tighten the lockknobs so that the axis does not drop while you arerepositioning the Altitude Adjuster Bar.

DO NOT Loosen
Pivot Bolt

LatitudeDegree Scale

5. Note that the Altitude Adjuster Knob is attached to a threaded rod that travels through the Altitude Adjuster Bar. Turnthe knob so that you see about half of the threaded rod protruding from both sides of the bar. This will allow you tomove the mount fully within the altitude range. The slots are positioned at 9 degree increments and the threaded rod
has 10 degrees of travel. They represent the following altitudes:a) Slot 1 - 0-10° center: 5°b) Slot 2 - 10-20° center: 15°

Socketc) Slot 3 - 19-29° center: 24°d) Slot 4 - 28-38° center: 33°

InsertRode) Slot 5 - 37-47° center: 42°

Altitude
Slotsf) Slot 6 - 46-56° center: 51°g) Slot 7 - 55-65° center: 60°h) Slot 8 - 64-74° center: 69°i)Slot 9 - 73-78° Note - it is necessary to remove thePolar Axis Lock Knobs and shift the mount into its 90°
position in order to utilize this upper slot. Once done,
lower the axis and restore the knobs.

Altitude Knob
Altitude Adjuster Bar & Socket

1100GTO shown in photo

6. Shift the Altitude Adjuster Bar into the correct slotted position. Note that the re-positioning is done so quickly and easily
that trial and error positioning is inconsequential. There is a degree scale on each Polar Fork with a corresponding
indicator line on the beveled edge of the worm wheel housing to assist you. See photos above.
7. Note that the threaded rod has a rounded end. Also observe that the underside of the R.A. Axis has an inset socket.
When you loosen the Polar Axis Lock Knobs and lower the polar axis be sure that the rod comes to rest fully seated inthis socket. A little wiggle of the adjuster knob will ensure its proper seating.
8. Turn the Altitude Adjustment Knob to raise or lower the Polar Axis to your approximate observing latitude (note thepreviously mentioned altitude lines on the side). Tighten the Polar Axis Lock Knobs with finger pressure only. You do
not need to tighten with the hex key.

14

9. Later, as you adjust the mount’s altitude when polaraligning, you should always make the final adjustments
pushing upwards. Additionally, the lock knobs should
be increasingly tightened as the final adjustments are
made.
Recommendation: Rough polar positioning of the mountand pier should be done with the R.A. axis only since you
will be making major adjustments to level the mount, aim it
north and set the elevation. The remainder of the mount,telescope and counterweights will add considerable weightand require more effort when positioning. Later, you will
do your actual polar alignment with telescope and counterweights attached, but the adjustments will be comparatively
small and within the range of the altitude and azimuth fineadjustments. An inclinometer and a compass adjusted formagnetic declination at your location (or these functions ona smart phone App) are recommended.

Indicator LineSpecial 90 Degree Alt-Azimuth Position

One of the unique design features of the 1100GTO mount is its ability to be placed into a 90° Alt-Azimuth position. This
allows specialized functionality for research applications, as well as terrestrial viewing. In order to achieve maximum
stability, it is important to maintain the center of gravity directly above the pier. This requires that the R.A. axis be reversedin the polar forks. The change over is outlined below in illustrations and description. Note: This axis reversal must be
done by two people...one to hold and reverse the axis and the other to remove and replace the bolts.
1. Remove telescopes and counterweights before beginning this orientation change. It is also necessary to separate theDec. axis so that you are only working with the R.A. axis and forks.
2. Remove all four Polar Axis Lock Knobs.
3. Tilt the axis upward to its maximum balanced position and remove the Altitude Adjuster Bar and set aside. The axis
must be held in place as there is no way to secure it.
4. While one person holds the R.A. axis, have the other person remove the two shoulder bolts that are the Pivot Bolts forthe axis. Remember that the full weight of the axis will need to be supported.
5. Lift the axis straightup and out of thepolar forks. Walkaround to the otherside of the mount sothat the R.A. axis canthen be lowered backinto place, but now
facing the other way.
6. Align the Pivot Bolts
with their respective
threaded holes andscrew into place. Do
not tighten them until
both bolts have been
fully threaded and theaxis rotated slightly
back and forth to ensure that it is properly seated. Now tighten the bolts fully.

(Not Used)

7. Replace the four Polar Axis Lock Knobs. Notice that they will all be in the lower channel. Two of the knobs are placed
into the available threaded holes that were previously unused. Use a bubble level to position the axis and secure theknobs tightly using a 1/4” hex key. You now have an Alt-Azimuth mount.
Important Note: We do not offer software for the 1100GTO mount configured in the Alt-azimuth mode at this time.
It will be necessary for you to write your own command protocol. However, it can be used manually via button
moves.

15

ASSEMBLY INSTRUCTIONS
Understanding Cabling Differences in Non-AE and AE Mounts

Offering the option of Absolute Encoders to the 1100GTO mount presented some design challenges. Apart from creating
a robust and high precision system, it was important to find an elegant and aesthetic solution that would minimize cableclutter and also take advantage of the mount’s internal cabling feature. A brief summation of the cabling differences
between the standard 1100GTO mount and the Absolute Encoder version of the 1100GTO mount (1100GTO-AE and
1100GTO-AEL) follows.

1100GTOThe 1100GTO mount (standard version) uses our traditional Y-cable design of the servo motor cable to connect the R.A.
and Dec. motors to the GTOCP4 control box. This Y-cable (S1100GYCR) is proprietary to the 1100 mount and cannot be
used with any other mount. Its longer Dec. branch is run internally through the R.A. axis and then exits a cable port on thefront of the Dec. axis. It then connects to the motor box. The cable port has a slotted cover that will slide shut and protect
against dust and insects. This cable is user installed.
Additionally, please note that there is a slotted access port
cover on the rear plate of the R.A. polar axis though which
the lower end of the Dec. cable can pass.
The R.A. servo cable branch will connect to the R.A. motor
box externally.
Finally, the connector which joins the two servo cablebranches will be attached to the GTOCP4 box at theconnector marked “motors”.

1100GTO-AE / AEL

The 1100GTO-AE and 1100GTO-AEL Absolute Encoder versions of the mount utilizea more complex cabling system that communicates encoder Readhead information
as well as the motor servo information. We call this cable system the X-cable system.
The Dec. AE Readhead connects to the motor
box via a 9-pin DE-9 connector. The encoder
information, along with the Dec. motor servo
information, is communicated via a single cablethat connects and looks like the cable described in
the section above. This cable is pre-installed at thefactory.
From the round connector on the motor box theservo cable runs through the cable port with theslotted cover and then internally through the R.A.
axis, exiting through the slotted cable port on the rear plate of the R.A. polar axis.
Unlike the Y-cable described above, this cable screws into to a junction box on theunderside of the polar axis.
The junction box sorts the Absolute Encoder and servo motor information/wiringof both axes. It has three cables hard wired into it. One cable on the east side
(northern hemisphere) goes to the R.A. motor box for communication to both
the AE Readhead and the R.A. motor
externally. The other cable on the eastside connects to the GTOCP4 connector
AE Readheadmarked “encoder”. The final cable exitingCable
the junction box from the west side
Servo Motorgoes to the GTOCP4 connector marked
Cable“motors”.

16

AE Readhead
Cable

Servo Motor
Cable

Junction
Box
R.A. Motor Cable
Dec.Motor Cable

Assembly of R.A. and Dec. Axes

One of the many features of the 1100GTO mount is internal cable routing. Internal cabling adds protection andconvenience. It eliminates many concerns, such as cable-snags and excessive dew exposure to electrical parts, whether
the telescope is in the backyard or at remote sites. Note: “Servo Cable” and “Y-cable” are used interchangeably.
If you choose not to utilize internal cabling for your 1100GTO(without encoders), you may custom order a longer Y-cablethat will allow you to run the cable externally in the more
traditional way of the 900 and 1200 mounts. In this case, you
would pass the cable around the left (west) side of the mountwhen attaching it to the Dec. servo connector. The low profile
design of the 1100 clutch knobs reduces the chance of acable snag, but know that it is possible.
If you route your Dec. Servo Cable through the mount, thenit is important to remember to detach the connection whenseparating the mount’s two axes. Otherwise, you will damage
an expensive cable and risk pulling the Dec. axis from yourhands as you start to walk away. These procedures apply
to all three versions of the mount, with or without absolute
encoders.

Assembly Procedure

This section assumes that you are only running the
motor cables through the mount. If you plan to run more
cables, please read the next section entitled “Cable
Management” before proceeding.

Channel (2)ClutchKnob(3)
Clutch (3)Cable
Router

Dec.
Servo
Cable

Dec. Lock
Knob
Dovetail
InsetsCable
Channel(3)

Polar Scope
Sighting Channel

Altitude
Adjuster
Knob

1. Ensure that the R.A. (polar) axis is securely attached to its pier before proceeding.
2. The Dec. Servo and Readhead Cable (Absolute Encoder mount) is pre-routed through the R.A. axis. The Dec. Servo
Cable (Y-cable of non-AE mount) will need to be routed through the R.A. axis by the user. Note that there is also a removable Cable Router provided with the mount which serves the purpose of keeping any internal cables out of the lightpath of the polar scope. If you will not be using a polar scope, then you have the option of not using the cable router.

FF B

O

A

Declination
Axis Lock
Knob (2)ON

3. Position the Dec. Servo
Cable along the side of the Cable
Router (if used) and loop it backinto the center of the insert. This
will keep the cable out of the way
when attaching the Dec. axis to
the R.A. axis. See photo at topof page.

Cable Router

4. Rotate the R.A. axis to the position shown in the illustration with the two clutch knobs at the top
and the single clutch knob at the bottom. Note that the channels
line up vertically and that the Dec. lock knob dovetail insets are at
the bottom. See photo at top of page.
5. During shipment, the Dec. axis lock knobs will be fully screwed
into the Dec. axis. You will need to back these out (approximately
8+ turns) until the tip is fully retracted.
6. Position the Dec. axis above the R.A. axis (see photo at left),then hook the top of the dovetails of the two axes together and tilt
the axis into place while giving a light wiggle so as to properly seatthem (shown by arrow “A”).
7. When the Dec. axis is fully seated, hand tighten the two lockknobs.
8. There are two 1/4” counter-bored holes (one on each side) on
the front of the Dec. axis. Insert a 1/4-20 x 5/8” socket head cap

17screw into each of the holes and tighten. These screws provide additional rigidity and security for the heavier capacityof the mount. When in public observing locations or when children are present the lock knobs could be loosened by
accident. This is an optional procedure. It is important that you tighten the lock knobs fully before adding thesescrews, so that the dovetail of the Dec. axis is properly seated.
9. Remove the Dec. Counterweight Adapter by unscrewing it. If it is too tight to turn by hand, you may insert a hex key
into one of the two holes at the side of the adapter in order to gain leverage. See photo in disassembly procedure
below.
10. Reach inside the axis and retrieve the Dec. Servo Cable that was inserted into the center of the R.A. axis Cable Router.
Feed the cable out through the cable port with the slidDec. Servo Cable Connection
ing cover raised and attach to the Dec. motorbox servo
socket. Note: Previous version of the mount is shown.
Dec. Cable
See photo at right.
Port
11. Once all of your cables are in place, lower the cable port
cover and replace the Dec. Counterweight Adapter. It is
not necessary to take great pains to tighten the adapter
since it will be tightened as the counterweight shaft issecured.
12. Thread the counterweight shaft into the Dec. Counterweight Adapter. Ensure that the Delrin washer is in placeon the threads of the shaft so that the shaft will be easierto remove later.

Dec. Servo Cable

R.A. Axis Center
13. Attach the Dec. Top Plate to the axis and lock it in place
Dec. Counterweight Adapter Removed
by hand tightening the two lock knobs. You may wish toplace and tighten the two 1/4-20 x 5/8” socket head screws that provide additional attachment security. It is importantthat you tighten the lock knobs fully before adding these screws, so that the dovetail of the Dec. Top Plate isproperly seated.

Disassembly procedure

1. Essentially, one reverses the assembly procedure. Start by removing the telescope, counterweights and counterweightshaft.
2. Remove the Dec. Counterweight Adapter by unscrewing it. If it is too tight to turn by hand, you may insert a hex key
into one of the two holes at the side of the cap in order to gain leverage.
3. Disconnect the Dec. Servo Cable at the motorbox connection asshown in the illustration (see above illustration). Feed it back throughthe cable port and tuck it back into the center of the R.A. axis forsafety and to prevent damage.

Dec. Cable
Port CoverDec. Counterweight
Adapter
Leverage
Hole (2)

DO NOT FORGET to disconnect this cable before separating theaxes!!!
4. Replace the Dec. Counterweight Adapter.
5. Remove the 1/4-20 security screws from the lock-down holes (if they
were used) and loosen the two Dec. axis locking knobs 8+ turns.
6. Separate the two axes as shown by letter “B” in the illustration in theassembly section.
7. For transport and storage, we recommend re-tightening the Dec.
locking knobs.
8. Place the R.A. axis in the zero-degree altitude position for compact
transport.

18

Note:

Remove Counterweight
Shaft before Adapter

CABLE MANAGEMENT

It has become more important than ever to find ways to manage cable routing. We now have the lure of imaging and withit the addition of accessories requiring power and computer connectivity. Apart from multiple dew heater cables, we now
have CCD cameras, color filter wheels, camera rotators, motorized focusers, autoguiders, adaptive optics units and thelist goes on... All these devices have power cables and USB or serial cables that need to be managed. To simply allow
all these cables to dangle would make your telescope look as though it is having a very “bad hair day” and it would invite
disaster. At the very least, dangling cables create flexure that results in bad star shapes in your images; at worst, theycause cable snags and damage to your equipment.
We have gone to great lengths in designing and engineering the 1100GTO mount to accommodate advanced cablemanagement. This job was made more complicated by our philosophy that our mounts should be portable and the twoaxes need to be able to be separated for the ease of setup and transport by our customers. Since our mounts can be
portable, we needed the ability to use a polar alignment scope for quicker set up time and alignment accuracy. We havesucceeded in our challenges. The 1100GTO allows you to pass all your cables through the mount while maintaining avisual path for a polar scope. It is the most advanced cable management system on the market today.

CAUTION! When running cables through your mount, you must keep in mind that they are there. To
avoid problems from twisting, DO NOT EVER rotate the mount a full revolution or more (> 360°) whilecables are inside. You can damage the cables. Operations where this might occur are balancing, regreasing and other maintenance activities. GTOCP4 software versions VCP4-P01-11 and later will notallow the servo to rotate the axes beyond this limit. If you rotate the mount, do not forget to de-rotate
it before continuing your activities.

Preparation

Think ahead! The key to good cable routing is good planning. Every imaging setup is somewhat unique. The equipment
is different and the selection of devices depends upon the type of imaging that interests you and the level to which you takeit. As systems become larger and more complicated, the greater the importance of planning and organizing. It is not as
simple to add a cable later since you may have to disassemble your system to do so.
It is best to lay out your imaging system and connect all the wiring so that you have a good idea which cables need to berouted through the mount. This can be done by spreading your devices on a table; they do not actually need to be set up
on a telescope. This will also allow you to have an idea about cable length, if there are choices to be made. Once you
have all your devices connected and know that you are not forgetting an important power cable or other critical necessity,
you are set to begin the actual process of routing your cables.
You may wish to consider reducing the number of cables needed by running a single power cable up through the mountto a power distribution hub, such as a RIGRunner, on top of your instrument package. Similarly, you can run a single
communication cable through the mount to a communication hub, such as an ICRON Ranger, located at the top. Using
these hubs can simplify and improve the quality of your setup.

The Basics

The 1100GTO mount has some very unique features that assist you with your cable management. Starting at the top of
the mount, you notice that there is a removable Dec. Top Plate. This plate allows you to attach various dovetail saddles
and specialty plates for the many, varied telescope systems to be found today. Notice that it has two cable channels
machined into it. It is also removable via a unique and powerful dovetail system so that you have unobstructed accessto the internal central routing core of the mount. The bottom of the Dec. axis also has a removable Counterweight Shaft
Adapter that unscrews to allow access internally so that routing cables can be done more easily.
The R.A. axis has a clever Cable Router which is removable. This router serves the dual purpose of organizing thecables while preserving a clear light path for the polar scope. In a permanent observatory setup, it is not necessary to use
the router, though it may be left in place, as it will not restrict the number of cables that can be run. It is designed to be
removable so that cables can more easily be routed through the mount and then replaced to secure the light path.
The final part of the internal cable routing system is the Cable Access at the bottom of the rear R.A. Plate. This accesshas two covers that are removable by undoing the socket head cap screws securing them. Once removed, cables withconnectors as large as RS-232 cables can be fed through the opening. It is always a good idea to feed the largest
connectors through first before moving on to the smaller sizes. If you do not plan to use a polar scope, you have theadditional option of routing the cables through the central opening.

The Specifics

What follows are more detailed instructions for installing your cable package into the 1100GTO. You will, of course,
have to tailor the instructions for your own particular needs. These instructions are for the routing of auxiliary cables forcameras, dew heaters, focusers and other devices that are not a component of the 1100GTO. The mount’s own cables are19

discussed earlier in this manual in the sections on mounting the declination axis. Use the Assembly Diagram found earlier
in the manual to help identify the named parts below.
There are two options for running cables through the 1100GTO. If you have the mount set up permanently in an
observatory and have no plans for the use of a polar scope, then you can choose to not use the Cable Router and can run
your cables through the mount while the two axes are joined. This has the advantage of more easily adding a cable laterby fishing it through the mount while assembled. If you will be using a polar scope for setting up portably or if you plan its
use at any time while set up permanently, then you will need to run your cables through the R.A axis first.
We shall first discuss the procedure for routing cables with the anticipation of using a polar scope. This option hinges on
the need for placing the wires through the R.A. axis and then placing the cable router. It may be possible to run cables withsmall connectors once the Cable Router is in place. As one sees in the illustration of the R.A. Axis Hub, the Cable Routercreates three narrow cable paths around the outside of the light path. However, the Cable Router is easily removed andreplaced in order to change existing cables or if you choose to add additional ones while the Dec. axis is detached.

Routing Cables if You Plan to Use the Cable Router When Using the Polar Scope
1. Start with the R.A. (polar) axis properly installed on your pier.

Cable
Router

2. Remove the Cable Router, if it is installed, and set it to the side for later use.
3. Remove the Cable Access Cover from the rear plate of the R.A. axis by unscrewing the two socket head cap screws. Store it in a safe place, as it will not be usedwhile cables are routed through the mount.
Note: you may find it helpful to also remove the Polar Scope Adapter Cap in orderto have more light and to better see what you’re doing. Just remember not to accidentally run a cable through the polar scope opening (assuming that you plan to
use the polar scope)!

4. Begin by feeding the cable with the largest connector from the front of the axis to the rear. You will need to finesse
the cable through the rear Cable Access opening. If you are having trouble coaxing the connector through the opening, you can
Cable
always use the electrician’s trick of first snaking a length of cord orRouterthick string through the cable channel by attaching it to the end of astraight wire or similar probe of sufficient length to pass through theLightaxis. Continue feeding your cables through the cable channel. Note
Paththat if you have a number of cables to run, then it may be best to use
another electricians trick and pull them all through at one time.
Important: Remember to route the Y-cable (Dec. servo cable)
or X-cable (Dec. servo and Readhead cable) along with youraccessories’ cables.

Cable
Channels

5. Insert the Cable Router into place while making sure that the installed cables are positioned in the channels. If you have a numberof cables installed, then you may wish to divide them between the three channels, or separate power and communication cables.
6. Since you must still attach the Dec. Axis, you do not want to have the full length of the cables running through the
R.A. axis, as the ends of the cables must be looped back into the center of the Cable Router as described in an earlier
section referencing the Dec. motor / communication cable. Loop the ends of the cables into the center of the Cable
Router. This is done in preparation of joining the Dec. and R.A. axes.
Polar Scope Cap
Cable
AccessCoversPolar Scope
Attachment
Hole Plugs (3)R.A. Axis Rear Cover Plate

7. Attach the Dec. axis as described earlier in the Assembly Procedure
section and lock into place with the Lock Knobs. You may wish to place
and tighten the two 1/4-20 x 5/8” socket head screws that provide attachment security. Remove the Dec. Counterweight Adapter.
8. At this point, unloop and route the Dec. servo cable through the cableport as described in the R.A. / Dec. Assembly section. Attach it to its Dec.
socket on the motor / gearbox and Readhead connector if your mount has
Absolute Encoders.
9. Next, unloop and route the remaining cables up through the center ofthe Dec. axis. Cable lengths can be adjusted at this point.

20

Note: It may be advisable to make a tool for snagging the wires and pulling them up through the Dec. axis. This can bedone by bending a wire clothes hanger (or similar wire) into a hook shape.
10. Decide which direction the cables should go (most will likely be towards the back of the scope, while some may best
be towards the front) and direct them accordingly through either of the two cable channels found on the Dec. Axis Hub.
This is a good time to further adjust the cable lengths as needed.
11. Attach the Dec. Top Plate and lock it in place by hand tightening the two lock knobs. You may wish to place and tighten
the two 1/4-20 x 5/8” socket head screws that provide additional attachment security. It is important that you tighten
the lock knobs fully before adding these screws, so that the dovetail of the Dec. Top Plate is properly seated.

Routing Cables if You Don’t Plan to Use the Cable Router
1. Start with the R.A. (polar) axis properly installed on your pier.
2. Remove the Cable Router, if it was installed.
3. Attach the Dec. axis as described earlier in the Assembly Procedure and lock into place with the Lock Knobs. You may
wish to place and tighten the two socket head screws that provide additional attachment security. Remove the Dec.
Counterweight Adapter and then unloop and route the Dec. servo cable (both encoder and standard Y-cable versions)through the cable port and connect it to the motor gearbox.
4. Remove the Cable Access Cover from the rear plate of the R.A. axis by unscrewing the two socket head cap screws.
Store it in a safe place, as it will not be used while cables are routed through the mount.
Note: It may be advisable to make a tool for snagging the wires and pulling them up through the Dec. axis. This can bedone by bending a wire clothes hanger (or similar wire) into a hook shape.
5. Begin by first feeding the cable with the largest connector through the Cable Access opening at the bottom rear of the
R.A axis. You will need to finesse the cable through the opening and up through the center of the axis. If you are having trouble coaxing the connector through the axis, you can always use the electrician’s trick of first snaking a length ofcord or thick string through the cable channel by attaching it to the end of a straight wire or similar probe of sufficient
length to pass through the axis. Continue feeding your cables through the cable channel. Note that if you have anumber of cables to run, then it may be best to use another electrician’s trick and pull them all through at one time.
Important: Remember to route the Y-cable (Dec. servo cable) or X-cable (Dec. servo and Readhead cables)
along with your accessories’ cables.
6. Now is the time to utilize the “snagging tool” that you so laboriously created. It can be used to reach the cables as they
peak out of the R.A. axis opening and you can then pull them up through the Dec. center. Alternatively, the electrician’s
trick of using a cord or thick string to pull the cables through the interior of the mount is a good one.
7. Decide which direction the cables should go (most will likely be towards the back of the scope, while some, such as
dew heaters, may best be towards the front) and direct them accordingly through either of the two cable channels foundon the Dec. Axis Hub. This is a good time to further adjust the cable lengths as needed.
8. Attach the Dec. Top Plate to the axis and lock it in place by hand tightening the two lock knobs. You may then use ahex key to give the knobs an extra eighth turn for tightness. Do not overtighten. You may wish to place and tighten thetwo 1/4-20 x 5/8” socket head screws that provide additional attachment security. It is important that you tighten thelock knobs fully before adding these screws, so that the dovetail of the Dec. Top Plate is properly seated.

Dec. Top Plate Removed

Dec. Top Plate in Place

21

ATTACH MOUNTING PLATE

1100GTO Dec. Top Plate Mounting Hole Pattern(purchased separately)
Several mounting plates (also called cradle or saddle plates) areavailable for the 1100GTO mount. If you own more than one
instrument, you may need more than one plate, or you may wish
to use one of the dovetail mounting plate options with more than
one male dovetail sliding bar. Attach your mounting plate withthe screws provided using one of the hole patterns shown atright. It is important to use the proper screws, please refer to the
instruction sheet entitled “Mounting Plate Fastener Chart.” This
chart is available at the end of this manual and in the technicalsupport section of our website.

Six 1/4-20 tapped holes
spaced @ 60° intervals
Bolt circle - 5.375”0°Four 1/4-20 tapped holes@ 45°, 135°, 225° & 315°
Bolt Circle - 3.200”

Optical
Axis

Outside diameter
6.275”

Fixed Mounting Plate Options

NOTE: All three of the plates described below have a hole spacing of 13.75”. This allows the use of the 15” dovetail plate(DOVE15) on top of your instrument as an accessory plate.

15” FLAT MOUNTING PLATE (FP1500) (Discontinued)
This plate is 15” long by 4.6” wide by 0.5” thick. Two pairs of keyhole slots that measure 3.2” between centers areprovided. The pairs are 13.75” apart. You can drill additional holes to suit your needs. This plate also fits the Mach1, 400,
600E and 900 German Equatorial mounts.
The 15” Flat Mounting Plate’s mounting ring hole spacing of
13.75” allows the use of the 15” Dovetail Plate (DOVE15) on topof your instrument as an accessory plate.
Attach this plate with four 1/4-20 x 5/8” socket head cap screws.

18” FLAT MOUNTING PLATE (FP1800) (Discontinued)
This plate is 18” long and 7.5” at its widest point in the center. The width of the plate tapers to 5.5” at each end. Four pairsof keyhole slots that measure 3.2” between centers are provided. The two inner pairs are 13.75” apart and the outer twopairs are 17” apart. You can drill additional holes to suit your needs. This plate also fits the Mach1, 900 and 1200 German
Equatorials.
Using the 18” Flat Mounting Plate’s available mounting
ring hole spacing of 13.75” allows the use of the 15”
Dovetail Plate (DOVE15) on top of your instrument as anaccessory plate.
Attach this plate with six 1/4-20 x 1” flat head socket cap
screws.

15” RIBBED MOUNTING PLATE (900RP)
The finished plate is 0.75” thick, 15” long and 6.5” at its
widest point. The width of the plate tapers to 4.75”. A pairof keyhole slots that measure 3.2” between centers areprovided at each end. The distance between these pairs ofholes is 13.75”. Due to the ribbed structure, you may not beable to drill additional holes to suit your mounting rings. The
plate weighs 2.3 lbs.
Attach this plate with six 1/4-20 x 1” flat head socket cap
screws. Note that the plate is asymmetrical. In most cases,
orient the plate so that the long end points toward the sky.
You can also turn the plate in the other direction to balance
your scope.

22

Losmandy D-Style Compatible Saddle Plates
10” Dovetail Saddle Plate for both D-style and V-style Plates (DOVEDV10) (replaces DOVELM2)This 10” Dual-style Saddle Plate fills the need of customers who
have multiple scopes. Often times the smaller scopes are outfittedwith Vixen V-style dovetail plates; whereas, the larger scopes havethe more stable Losmandy D-style plates. The DOVEDV10 is theperfect solution as the best of both worlds.
It is a very robust dovetail saddle that will securely attach all yourscopes to the mount. The clamp design provides the strongest
possible lock for both style plates. The saddle has three locking
clamps. Using all three will provide extra security, while using one of
the end clamps along with the center clamp will allow shorter dovetailplates to be secured.
The clamping blocks grip your dovetail plate firmly. Springs keep the blocks in an open position until you tighten the knobs.
The unique design of the clamping blocks ensures that they remain properly aligned with no need for additional guide pins
and the brass washers on the knobs allow firm tightening without binding.
The saddle has the convenience of the Astro-Physics tilt-in feature applicable to both style plates. It has additional
attachment holes so that the saddle can be shifted forward or backward, depending on whether you are balancing a frontheavy or back-heavy scope. In addition to D-style plates, it matches well with the Astro-Physics 15” V-style Plate (SBV15).

16” Easy-Balance Dovetail Saddle Plate for Mach1, 900, 1100, 1200 and 1600 Mounts and Losmandy
D-Style Plates (DOVELM162)
This Astro-Physics plate was introduced in
February, 2009, and in mid-2010 we added thecenter clamp for even greater versatility. The
DOVELM162 provides a multitude of mountattachment options, and was specificallydesigned to meet the balancing demands of“back-end-heavy” instruments like SCTs andRitchey-Chrétiens, especially those with heavy
imaging gear hanging off the back!
This plate has small knobs to avoid interference with the declination hub, but the knobs have cap screws in the ends that
accept a 3/16 hex wrench for extremely secure clamping of your instrument. Additional features include ribbed structure
underneath to reduce weight and tapped 10-32 holes in the side for cable attachment. This is the perfect saddle for our
16” Versatile Dovetail Plate (SBD16)!
Note that the bolt-hole patterns are marked with scribe cuts. The four-hole patterns can all be supplemented with bolts
along the optical axis in the six-hole pattern giving six attachment points at each position. Attach this plate with four 1/4-20
x 1” socket head cap screws and possibly one or two 1/4-20 x 3/4” flat head socket cap screws.

23Side-by-Side and Vixen Style Plate Options
Many of our customers enjoy the convenience of aside-by-side configuration. Often a nice pairing for a
versatile visual setup might be a wide field refractor
along with an SCT or Maksutov Cassegrain for
high-power viewing or its greater light grasp. We
never recommend using a side-by-side mounting
as a guidescope / imaging scope setup due to thepossibility of differential flexure. However, using
an off-axis guider with either scope can make forsuccessful imaging.

13” and 18” Side-by-Side D-style Plates(SBD13SS & SBD18SS)
These plates will fit into any D-style compatible plates
and will accept the DOVELM2, the DOVEDV10 or the DOVELM162 as the instrument saddle plates for each scope. The
13” plate allows optical axes to be placed on 9.5” (250 mm) centers, and the 16” plate allows instruments on 12.5” (318mm) optical centers.

15” V-style Dovetail Plate (SBV15)
This 15” long Vixen V-style dovetail plate is designed to add maximum strength and rigidity to your scope setup. It uses awide attachment surface with the 2.362” (60 mm) side-to-side hole-pattern of Astro-Physics and many other scope rings,
along with the universality of center slots.
Though it was designed to be used with the 10” Dualstyle Saddle Plate (DOVEDV10), the SBV15 can beused with all Vixen V-style OEM systems.
The plate can also be used as an accessory plate by attaching it to the top of rings. This will allow affixing a variety ofaccessories using V-style adapters.

Other Mounting Plate Options
Additional mounting plate options including custom plates may be available from other sources. The hole patterns for the
declination hub are shown on the illustration on page 15.

24

ATTACH COUNTERWEIGHT SHAFT AND COUNTERWEIGHTSIMPORTANT:● Always attach the counterweights before mounting the telescope to the saddle plate to prevent sudden
movement of an unbalanced tube assembly, which may cause damage or injury.
●

Remember counterweights are heavy and will hurt if they fall on your foot.

1. Thread the Counterweight Shaft onto the Dec. axis. Be careful not to cross-thread! Do not tighten too much, since you
will need to remove it. Also be sure that the Delrin washer is in place on the threads to facilitate the shaft’s removal
later.
2. Remove the machined Safety Stop from the end of the Counterweight Shaft, if it is attached. Add sufficient counterweights (5, 10, 18 or 30 lb. counterweights are available) to the shaft to balance the telescope you intend to use. Loosen the counterweight knob and hold the counterweight with the knob pointing downward so that the brass pin will movefrom the center opening allowing the counterweight to slide into position. Always use two hands to attach or movethem on the shaft. It is advisable to have the counterweight knob pointing down toward the pier. This will minimize thechance of accidentally loosening the counterweight during the observing session.
3. Re-attach the Safety Stop to the end of the Counterweight Shaft. This will help to prevent injury if someone accidentally loosens the counterweight knob.
NOTE: A firm tightening of the counterweight knob will not damage the surface of the Counterweight Shaft. The pin thattightens against the stainless Counterweight Shaft is constructed of brass.

ATTACH MOUNTING RINGS AND SCOPE(purchased separately)

If this is your first session with your new mount, you may wish to read the “Understanding R.A. and Dec. Clutch
Knobs” section before attaching your telescope. This will give you an idea of how the clutch knobs feel andfunction.
Flat and ribbed plates: Our flat and ribbed plates are constructed with keyhole slots at the location where your mounting
rings attach. This feature enables you to partially loosen the screws on your rings just enough to insert them into the larger
part of the keyhole, then slide the rings to the narrow part and tighten them with a hex key. We prefer this keyhole method
to the standard way of completely removing the screws and dropping them in the grass.
We suggest that you install the rings on the mounting plate, then open the rings, lift the scope in place, close the rings andtightened the knobs. To balance the scope, you can loosen the knobs enough to slide the scope forward or backward asneeded.
Another approach is to attach the rings to the scope beforehand, then lift onto the mounting plate. However, the rings mustbe spaced exactly the correct distance apart to match the holes in the plate. This maneuver may be particularly difficult toaccomplish with a large, heavy instrument.
Dovetail plates or sliding bars: Attach mounting rings to the male dovetail plate (sliding bar) matching the appropriate
threaded holes on the bottom of the mounting ring. Again, you have the option of attaching this dovetail / ring assemblyto the mount and then lifting your scope in or placing the scope in the rings, then lifting the entire assembly to the female
mounting plate already attached to the mount. Dovetail plate / sliding bar combinations are quick, versatile and convenient– hence their popularity. Simply loosen the knobs and “tilt” the sliding bar into place in the dovetail receiver. Once in place,tighten the knobs to lock everything securely. Loosen the knobs and slide the scope / rings / sliding bar assembly in thedovetail channel as needed to balance the system, and then re-tighten when balanced.

25

UNDERSTANDING THE R.A. AND DEC. CLUTCH KNOBSWARNING! Be careful when moving the mount with the clutches. It is possible to catch cables orfingers between the clutch knobs and the motor / gearboxes if you are not careful!
CAUTION! When moving the mount via the clutches, the servo is not involved, and therefore is
not keeping track of the axis’ positions. Bear in mind that internally run cables can be twisted anddamaged if you are not keeping track of, and accounting for movements made using the clutches.
If cables are run internally, you do not ever want to rotate an axis more than 360°. If you rotate themount, do not forget to de-rotate it before continuing your activities.
1. What do they do?
The three R.A. and three Dec. Clutch Knobs depicted in the Assembly Diagram have the function of connecting the
R.A. and Dec. Axes to their respective drive worm wheel gears. Their function is progressive, from slight tension (axesfree to move - as required during correct balancing of the telescope) to a completely “locked up” state.
2. How can you find out what they really do?
As shipped, all 1100 mounts have both sets of R.A. and Dec.
Clutch Knobs firmly hand tightened. This will give you a goodidea of the maximum tightness (clutch action) that can beachieved by hand effort alone. At this point, you must bear inmind that for optimum performance all three clutch knobs oneach axis (R.A. or Dec.) should be tightened evenly to the same
tension i.e. all three half tight, all three fully tight, etc.

Clutch Knobs

Dec. (3)In order to feel the effect of the clutch knobs, you may wish topartially assemble your mount. Fit together the R.A. and Dec.
R.A. (3)Assemblies plus mounting plate and counterweight shaft. Do
not put scope and counterweights on at this stage. With theabove assembly (with the clutch knobs firmly hand tightened “as shipped”), you can feel the amount of force needed to moveeach axis by hand. Grab each end of the telescope mounting
plate and move it with a backward and forward movement of theDec. Axis. You will feel considerable resistance to this motion. Perform the same operation on the R.A. axis by moving the counterweight shaft backward and forward. With a well-balanced telescope, the above tightness of the clutchknobs will be sufficient for all normal conditions of use.
Now, if you proceed to mount up and balance your telescope, you can “feel” what this resistance in R.A. and Dec.
(movement backwards and forwards) is like when you make these motions from the eyepiece end of your telescope as
you would during normal use when slewing (pushing) by hand to acquire an astronomical object within the field of viewof your finder or scope.
3. How tight can the clutch be and can you do any damage by pushing against them?
The clutches cannot be damaged by tightening; however, it is not necessary to tighten them as you would tighten the
lug nuts of your car’s wheel. You will see that each clutch knob has a 5/32 hex socket for tightening with a hex key.
With an extra 1/5 turn beyond hand tightening on each clutch knob, the axis (axes) will be considered completely“locked up” and you should not attempt to push your scope by hand against this “locked up” resistance, or undue stresswill be placed on the worm wheel / worm and bearings.
Naturally, if you have a very heavy load, it is advisable to tighten the clutch knobs more than is necessary when a lighter payload is mounted. When imaging you’ll want to ensure that the clutches are tighter so that there is no slippage.
4. How do the Clutch Knobs of the 1100GTO differ from all 900 and 1200 mounts?
The 900 and 1200 mounts were designed with Delrin clutch plugs beneath the knobs. While these were quite effective as a clutch material and did not damage the underlying worm wheel surface, over time the base of the clutch plugs
spread out after being tightened with greater force than necessary, preventing their full release.
The 1100GTO uses a different clutch system, and it also uses a different bearing system for the free rotation of theaxes. It will feel stiffer than the 900 or 1200 series mounts.
You should be aware that the clutch knobs on the 1100GTO have spring loaded tips that may still be applying pressure
to the clutches, even though the clutch knobs feel loose. Back the clutch knobs off by at least two or three full turns tomore fully disengage the clutches. There will always be some friction. The 1100GTO clutches can be fully tightened
without worry.

26

BALANCING THE TELESCOPE

To achieve the best performance from your mount, your telescope should be well-balanced. This is more important for
imaging setups than for visual setups since greater precision is required for guiding. Those who are setting up for visualuse or casual imaging need only be “adequately” balanced, as the mount’s drive system is very robust.
Common sense dictates that you want to begin the balancing procedure with your setup counterweight heavy so thatthe scope does not suddenly leap from your hands and spin around into the pier. As long as the counterweight is down,
sudden movements of the Dec. axis cannot cause a damaging mishap. You will want to perform the balancing with thescope set up exactly as it will be used. Eyepieces, diagonals, finder scopes, cameras, guiders, etc. should all be in place
before you begin.

Preliminary Balancing

1. With the counterweight shaft down and the scope pointing toward the pole (Park 3), loosen the Dec. clutch knobs(about 3 to 4 full turns) and feel which way the scope’s weight is offset. Placing a hand on each end of the scope andlifting back and forth will give you a good feel for balance. Slide the scope (in its rings or via the dovetail) until it feels
balanced, then point the scope to the north again and tighten the clutches.
2. Next, loosen the R.A. clutch knobs (about 2 to 3 full turns) and, while holding the counterweight shaft, move the axis
into a horizontal orientation. You will probably need to rotate the Dec. axis a bit so that it also assumes a horizontal
orientation. Place a hand at the end of the shaft and on the scope and, lifting back and forth, make counterweightadjustments to equalize the balance as well as possible.
This degree of balancing will be sufficient for those who wish to have some fun doing visual observing with family andfriends. DO NOT disengage the gearbox for rough balancing. Disengaging the gearbox on an out-of-balance system
can damage the worm gears! If you are planning to do long-exposure, deep-sky imaging, then you’ll want to refine thebalance. The steps below will walk you through precision balancing.

Precision Balancing

Do the preliminary balancing first using the clutches! (see above)
Remember that dangling cables will dramatically change balance andcreate guiding problems, so you’ll want to be sure that all cables arecarefully secured and not dragging before you proceed with precisionbalancing. Ensure that your focuser is in its focused position, thedew shield extended with the dust cap removed and the diagonal witheyepiece or the camera equipment installed. Think: Ready-to-Image!

Add

10 lb.

24 lb. 24 lb.

Fine
balanceadjust24 lb. 24 lb. 24 lb.

24 lb.

The counterweights should ride high on the counterweight shaft. It isbest to add counterweights and slide them to the top of the shaft with theheaviest at the top and then use the smallest weight to perform the final
precision balancing. The reason for this is called “Inertial Moment Arm”.
Sliding less weight down the shaft will balance the scope, but will greatly
increase the moment arm force; that is to say, it will require a muchgreater torque to start the axis rotating. (Think of a tightrope walker using
a long rod to stabilize his balance.) This is a very important consideration
when you are trying to do precise guiding. See illustration at right.

10 lb.

Note that with previous designs of mounts we recommended slightly
offset balance to the counterweight side of the R.A. axis and slightly
offset balance to the camera side of the Dec. axis. This is no longer true
with our current self-adjusting motor box design. Balance should be as
exact as possible when imaging. Balance Dec. and then R.A.

Yes

No

We also DO NOT recommend using an ammeter to balance the mount. At the level of precision balance, friction
differences and other factors will completely overwhelm the contribution to current draw made by imbalance.

Disengaging the Worm and Worm Wheel for Precision Balancing
The new motor / gearbox design allows complete disengagement of the worm from the worm wheel allowing theaxis to turn freely for careful balancing. It is important to begin with the scope approximately balanced since it will befree to abruptly spin when the gears are disengaged. You definitely do not want the scope to yank from your hands andcrash into the pier! Important: Start this process in the safe Park 3 position - dangerous swings are avoided.
On the following page is a pictorial sequence that shows how to disengage the gears. It is as easy as flipping a lever!

27

Remove
Lever Assembly
Cover

1. Grip the lever assembly cover and pull it free to expose the lever inside. There are grooves on either side of the cover
to assist with your grip.
2. Rotate the lever 180º to disengage the worm (never force it past its limits). When you rotate the lever, the motor gearbox will tilt and disengage the worm from the worm wheel. Caution: The axis will spin freely when disengaged.
3. When balance is complete, gently turn the lever halfway until the spring engages the gear teeth. Shift the axis backand forth slightly to ensure that the teeth have fully engaged.
4. Once the teeth have fully engaged the lever can be rotated fully into place and the cover replaced. Do Not force thelever! No never! Not ever!

VERY IMPORTANT: Begin the balance process in Park 3 position so that there is not an abrupt swingof an out of balance scope which can damage the worm wheel teeth!!!
Ok...Let’s balance!
1. Be sure that a preliminary coarse balance has been done so that no unexpected swings of the scope take place. Be
sure that the clutches are tight on both axes. You will not use the clutches to balance the mount.
2. R.A. Axis – Release the gear mesh in the R.A. axis as described in the pictorial above. While holding onto the counterweight shaft, swing the shaft to a horizontal position either east or west to your convenience.
3. Slide the heavier weights to the top of the shaft and try balancing with just the lower, lighter weight. If you must, slide
the weights lower as necessary to balance, however, it is better to add another heavy weight up high. The balanceshould be precise for good guiding when imaging.
4. Position the axis horizontally and then gently turn the lever to re-engage the worm and worm wheel as describedabove. You may need to slightly rotate the axis so that the gears drop into mesh before fully engaging the lever.
5. Once the lever is fully in its locked position, replace the cover and move on to the Dec. axis.
6. Dec. Axis – Release the gear mesh in the Dec. axis as described in the pictorial above. While holding one end of thescope, swing the scope into a horizontal position.
7. Loosen the tube mounting rings or the dovetail saddle locking knobs and position the scope so that it is perfectly balanced and stable in a horizontal position. Remember that the camera should be in its focused position for accuracy.
The balance should be precise for good guiding when imaging.
8. Position the axis horizontally and then gently turn the lever to re-engage the worm and worm wheel as describedabove. You may need to slightly rotate the axis so that the gears drop into mesh before fully engaging the lever.
9. Once the lever is fully in its locked position, replace the cover and you are finished. Now you can loosen the clutches
and reposition the scope into a reference Park position so that you can power up and be oriented.

28

BALANCING SIDE-BY-SIDE
In a nutshell, this is what you should do. If you are careful about following this procedure without shortcuts or“guesstimates”, you will save a lot of time and effort in the long run. People look at the procedure and say, “Heck with it, I’ll
just wing it.” They usually end up sorry!
The key is preparation! You are balancing 3 systems. Do ALL of this on a worktable, preferably with a helper.
1. Balance the first system.
a) Fully assemble one of the telescope systems you will be using. This includes, but is not limited to:i)

The dovetail for that scopeii) The rings or other attachment mediumiii) The complete imaging train including all adapters, correctors, telecompressors OAGs etc.
iv) All guiding hardware, if it will be on this systemv) Any finders or other devicesvi) Any special wiring harnesses or electronic devicesvii) Dew Heaters and controllers.
viii) ANYTHING that will be attached to this system!!
b) Adjust focus as close as possible to where it will be for imaging.
c) Place a dowel rod under the mounting plate to create a seesaw. BE CAREFUL!!
d) Using the dowel rod as a fulcrum, find the exact balance point of the system.
e) Mark the exact balance point with a piece of blue painter’s tape.
2. Balance the second system.
a) Basically, repeat the above steps.
3. Since the two parallel dovetail saddle plates are probably somewhat offset, we need to next balance the side-by-side
plate trio FRONT TO BACK first.
a) This should just be the bottom transverse dovetail plate and the two parallel saddle plates that are bolted on top.
Nothing else.
b) Run the dowel rod lengthwise under the bottom dovetail plate. Try to keep it parallel with the transverse plate.
c) Balance the trio of plates front to back on the dowel rod.
d) Mark each saddle plate at the point where it balances over the dowel.
e) Remove the dowel rod.
4. Attach each scope system. Simply line up the tape balance points on each saddle with the tape balance points oneach of the parallel saddles.
5. Now place the dowel rod back under the bottom dovetail plate, but this time it is perpendicular to the dovetail (parallelto the OTAs).
a) Rock the system back and forth until you find its balance point.
b) Mark the bottom dovetail with tape at the exact balance point.
6. Put the entire system into the primary saddle plate. This plate will have limited adjustment because it is fixed by its
mounting holes. The final part of this is the trickiest.

29a) Our saddle plates offer several mounting options. Look at the setup in front of you and decide which set of mounting holes will best serve your needs.
b) Mark the center of the mounting hole pattern that you will be using with tape. This may not necessarily be theperfect balance point.
7. Place the dowel rod under the center of the mounting hole pattern.
8. Now, adjust the bottom dovetail in the saddle until the system is balanced above the dowel that is in the center of the
Dec mounting hole pattern.
9. Mark the saddle and bottom dovetail so you know exactly where the dovetail needs to be positioned.
10. Take everything apart, but DON’T LOSE THOSE TAPE PIECES!!
11. When you reassemble, simply line up your tape pieces and 95% or more of your Declination side-by-side balancing will
be done.
12. Final note: When balancing RA, more weight higher up on the shaft is better than less weight further down the shaft.
If the preliminary work is done carefully, you will blow anyone away who might be watching you. Most experienced
observers shake their heads when they see someone trying to set up a side-by-side system because they know how hard
it can be to get the thing properly balanced. It is very satisfying to put the pieces together and have near perfection rightfrom the get-go!

30

ALTITUDE AND AZIMUTH ADJUSTMENTS – ROUGH POLAR
ALIGNMENT
It is recommended that you not attach the RAPAS until you have roughly centered Polaris through the site hole.
For rough polar alignment, your goal is to sight thecelestial pole when looking through the polar alignment
sight hole. You will need to make altitude (up/down) andazimuth (side-to-side) adjustments to the position of themount.
[An inclinometer and a compass adjusted for magnetic
declination at your location (or these functions on a smart
phone app) can be very helpful for daytime setup. In
addition, be sure to learn the Daytime Polar Alignment
Routine as described in the keypad manual. It is a great
method for rough alignment!]
Note on Bubble Levels: It is possible to achieve
perfect polar alignment without having the pier level, but
it is slightly more difficult. With a pier that is not level,
each adjustment in azimuth also causes a minor shift inaltitude and vice versa. This is why we have included
the bubble level on the 1100GTO. However, don’t waste
time obsessing about having the pier perfectly level. This is, after all, NOT an Alt / Az mount! Devote the time to the actual
polar alignment instead. If you are reasonably close to level, you will not be able to notice a difference. Keep in mind thatunless you are a serious astrophotographer or imager, “perfect” polar alignment is not critical.
1. Remove the Dec. axis sight hole cover, to complete these steps. Examine the polar axis assembly and you will seethat the center of the R.A. shaft is hollow.
Azimuth Threaded
Push Rod
h
ut

k

oc

Bl

im

Az

Azimuth Adjuster Knobs

2.
Azimuth adjustments: Depending upon how accurately you
positioned your mount when setting up, you may need to move orturn the entire pier or tripod east or west until Polaris can be seen
through the sight hole. If Polaris is already in view, you will use thetwo fine azimuth adjustment knobs, one on each side of the mount,to center it. You must back off the opposing azimuth knob in orderto move the other knob in that direction.

One full turn of the azimuth knob is approximately 0.668
degrees (40.5 arcminutes). Small graduations are 1.62
arcminutes; long graduations are 8.1 arcminutes.

The best adjustment technique to use with the Astro-Physics Azimuth Adjuster, with its clear registration marks for fineadjustment, is to back off one of the knobs by a set amount (a certain number of registration marks) and then to turn theother knob until you re-establish contact on both sides of the Azimuth Adjuster Block. You can very precisely zero in on thedesired position with no backlash or ambiguity on the position. You can also always go back to the precise starting point
if for some reason you overshot your mark (or if you adjusted the wrong way), because you know exactly how far you’vegone. This is explained further in the section on Fine Polar Alignment.
3. Altitude (latitude) adjustments: Loosen the Altitude Lock Knobs. Move the polar axis up or down with the large
Altitude Adjustment Knob located in the front of the polar axis assembly.

One turn of the altitude knob is approximately 0.6031 degrees (36.1 arcminutes).
4. Continue your azimuth and altitude adjustments until you center Polaris in the polar alignment sight hole. At this point,
you have achieved a rough polar alignment, which may be sufficient for very casual visual observations, if you are notplanning to slew to target objects. When the R.A. motor is engaged (the power is plugged in), it will compensate for therotation of the earth and keep the target object within the low power eyepiece field of view. Your target object will slowly
drift since polar alignment at this stage is only approximate. However, you can make corrections with the N-S-E-W buttons of your keypad controller.
5. Tighten the Altitude Lock Knobs by hand.

31

POLAR ALIGNMENT OPTIONS – FINE POLAR ALIGNMENT
For very casual visual observation, you may skip this section and simply start observing. A finder-scope or single power
finder may be required to locate objects since GoTo slews with the keypad require good polar alignment for spot-on
accuracy. Don’t forget to tighten your Altitude Lock Knobs (4) before you begin! For casual visual observation, you canmove the telescope manually via the clutches or by using the GoTo and centering functions of the keypad.
The keypad and GTO Servo Control Box will function as soon as they are plugged in. That means that the R.A. axis will bemoving westward at the sidereal rate. Note, however, that this motion will not be accurate enough to qualify as “tracking”
without accurate polar alignment. In short, if you will depend on the GoTo functions of the 1100GTO, or if you intend to do
astrophotography, you must perform a more accurate polar alignment. Some methods, procedures and tips are presented
below. You will complete this alignment when your scope and other equipment are mounted.

Methods for fine polar alignment●

Polar Alignment Scope – Our optional Right-Angle Polar Alignment Scope (RAPAS) will allow you to quickly alignyour mount on the pole. The reticles are designed for use in both the Northern and Southern hemispheres. Even
users of the GTO computerized mounts will find these polar scopes useful, particularly if your telescope is notorthogonal to the mount (please refer to the keypad manual for a discussion of orthogonality). If you have a polaralignment scope, please read the instructions sheets that come with it. If you are planning long-exposure astroimaging, we suggest that you use the polar alignment scope, then tweak the final polar alignment by using traditional
drift alignment, the GTO Quick Star-Drift Method (refer to the Keypad v4.19.3 manual), PEMPro™ Pole Align Wizard
or other similar alignment program.

●

GTO Keypad – Please refer to the instruction manual for the GTO Keypad and read the sections from “Getting
Started” through “Alternate Polar Calibration Routines & Tips.” As time goes on, the keypad manuals will be updated.
Please refer to the Technical Support section of the website for the most recent documentation. Here are summary
descriptions of several techniques for polar alignment from the current Keypad Manual available on the TechnicalSupport page of our website.
○

The Keypad startup routine provides two methods: The North Polar Calibrate and the Two Star Calibrate.
These two polar alignment methods, though no longer recommended, were designed for quick and coarsealignment in the field with portable setups. They are for visual observers, not imagers. The Two Star Method
is the better of the two as it is less affected by the extremely low resolution in R.A. near the pole and byorthogonality issues.

○

The Daytime Routine (see “Polar Aligning in the Daytime” in the Keypad Manual), is a great trick for daytime
setup. It will allow you to “wow” your friends by setting up and finding planets and bright stars in the daytime.
In addition, it is the recommended first step in alignment for anyone in the southern hemisphere. Even thosein the south who own our polar scope will find it helpful, since it will generally put the rather difficult-to-spot
southern stars into the polar scope’s field of view.

○

The GTO Quick Star Drift Method is for use with a finder scope. By using a finder scope, you are able toremove orthogonality issues from the process, making subsequent alignments much easier.
Using the Daytime Routine, followed by the GTO Quick Star Drift Method, will provide accurate enoughpolar alignment for extensive imaging. This combination is our recommended procedure for anyone in thesouthern hemisphere, or anyone who finds their view of the pole obstructed.

●

Computer Software Solutions○

Polar Align via PEMPro’s “Pole Align Wizard” – PEMPro™ is a software by Ray Gralak and distributed by
CCDware. This powerful application not only analyzes and improves the periodic error performance of any
mount that is equipped with a CCD camera and compatible camera control software, but also includes “PoleAlign Wizard”.
“Pole Align Wizard” is one of the best method of accurately polar aligning! It is like traditional drift aligning,but on steroids! It has the advantage of automatically choosing the optimized stars for drift aligning and does
not have to worry about star magnitude since the CCD can see dimmer than an eye. Also, it compensates for
air refraction and other variables that manual drift aligning cannot. It does require the use of a CCD camera
and corresponding camera control software. The Wizard walks you through the alignment process with easy
step-by-step instructions. Note: This and the R.A. Correction Method (on the Technical Support pageof our website) are the preferred alignment method when tweaking the RAPAS orthogonality.
A full PEMPro™ edition is included with the 1100GTO, 1600GTO and 3600GTO mounts (sorry, not theMach1GTO).

32

○

●

Other Software – There are many software packages that include aids to polar alignment that can be foundthrough a Google search. Some will work better than others. Do not be fooled into thinking that youralignment is perfect simply because a piece of software told you so. Polar Alignment is, after all, entirely
a mechanical issue. Apart from “Pole Align Wizard”, we do not have experience with these other software
programs and cannot vouch for them or provide support.

Star Drift method – Traditionally, this very time-consuming procedure has been regarded as the most accurate
method of polar alignment. However, if you are using the old method of drift alignment that employs stars near theeastern or western horizon, you may encounter problems from atmospheric refraction, which will skew your alignment.
To obtain more accurate results, choose stars somewhere near the celestial equator due south or slightly east andwest, but not below 45 degrees elevation.
For portable setups, we believe that our GTO Quick Star Drift Method using the Meridian Delay Feature and a
Finderscope (found in the keypad documentation as noted above) is a much more practical approach in terms ofproviding highly accurate alignment and still leaving enough time to actually get some imaging done. A permanent
observatory setup where long unguided exposures are taken may still benefit from a final tweaking using the traditionalstar drift method (as modified by the 45 degree elevation recommendation above) or from a software enhanced variant
like the PEMPro™ Pole Align Wizard that allows a CCD to measure and calculate the drift much faster than can bedone at the eyepiece.

●

DRIFT ALIGNMENT – R.A. CORRECTION METHOD – Please see the Technical Support page of our website forthe instructions to this alignment technique. This will provide the highest precision of polar alignment with the least
amount of drift within 45 degrees of the zenith (where most imaging is done). Note: This and the “Pole Align
Wizard” are the preferred alignment method when tweaking the RAPAS orthogonality.

Making Precise Altitude and Azimuth Adjustments

The mechanics of altitude and azimuth adjustment are relatively straightforward. In the discussion below, we will provide
some information and tips that will give you the greatest success with your 1100GTO regardless of the polar alignment
method you choose for determining the amount and direction of each adjustment. We’ll leave the choice of method up toyou. (Did we mention the GTO Quick Star-Drift Method?) We list the fine altitude adjustment first because our GTO Quick
Star-Drift Method begins with altitude. Many texts for the classic star-drift method begin with the azimuth adjustments.
When you made your rough alignment earlier, you loosened everything up, got the mount close, and then tightened
everything back down. Any minor shifting that occurred from locking things down tight was of no consequence since it
was a rough procedure. Now you are fine-tuning the alignment. Regardless of whether you start with altitude or azimuth,
begin the fine adjustment process with everything locked down as if you were already finished. Then, loosen only what isrequired to make the adjustment, and loosen as little as possible. Your final adjustment should always be with everything
virtually, but not quite fully locked. It is may be helpful to use the technique of tightening the knobs a little more with eachnew adjustment.

Fine Altitude Adjustment

Slightly loosen the four Altitude Lock Knobs, but do NOT loosen the polar axis pivot screws. Move the polar axis up or
down with the large Altitude Adjuster Knob located in the front of the polar axis assembly. If lowering the axis, you may
need to “help” the axis down if your lock knobs are somewhat tight. If you lower the axis, always be sure that the axis
remains in firm contact with the stainless steel thrust pad. Please refer to the illustrations earlier in this manual if you are
unsure about these parts. Final adjustment should always be made pushing up in altitude.

One full turn of the altitude knob is approximately 0.6031 degrees (36.1 arcminutes).

Tips for Adjusting the Altitude

1. The mount’s polar axis is held in place between the two side plates. It is possible for the mount to shift slightly when thelocking knobs are fully tightened down after adjustment of the altitude angle. To prevent this shift, it is suggested thatthe initial fine altitude adjustment be done with these knobs hand snugged, and as you approach the final adjustment
point, tighten the knobs, first to hand tight, and finally with a hex key after each small movement. As you converge on
the pole in altitude, each successively smaller adjustment is made against greater resistance from the ever tighter lockknobs.
2. Approach the pole from below and try not to overshoot. If you accidentally move the axis too high and overshoot thealtitude angle, it is better to loosen the four lock knobs a bit, and bring the axis back down a very small amount before
proceeding back up with the knobs tightened up again. This way you are using the weight of the mount to insure asolid connection to the altitude adjuster. The “captain’s wheel” design of the Altitude Adjuster Knob provides the necessary leverage during the final “tweaking” adjustment phase when the locking knobs are quite tight.

33

Fine Azimuth Adjustment

The one-piece Azimuth Adjustment assembly makes for easy and accurate polar alignment in your observatory or in thefield, and it eliminates issues of adjustment backlash. The heavy-duty construction and integrated one-piece design resultin smooth control of the azimuth axis. Large left and right adjuster knobs are graduated for precise control of azimuth
position angle.

The small graduations are 1.62 arcminutes per graduation; long graduations are 8.1 arcminutes per
graduation; one full turn is 0.668 degrees or 40.5 arcminutes.
The size of the knobs makes them easy to turn with very little torque required, even with the mount fully loaded. Takefull advantage of the graduation marks on the Azimuth Adjuster when performing fine alignment to mark your startingand ending points for each adjustment. This will allow you to exactly undo any adjustments that are made in the wrong
direction. Do not leave the knob you have backed off loose. When finished, both knobs must be tight against the azimuth
adjuster block to hold the azimuth angle you have set. If you follow our hint below, the act of adjustment will leave theadjusters tight against the azimuth adjuster block!
Important Hint: The natural tendency when making azimuth adjustments is to first back one adjuster knob off asignificant amount, then make the required azimuth adjustments with the other knob, and then when finished, totighten the first knob back up against the azimuth block. This can result in a slight shift as the first knob is tightenedagainst the block. We recommend that you completely abandon this approach for fine azimuth adjustment.
Instead, we recommend that you start with both knobs tightened against the azimuth adjuster block. Then, back off
the first knob only by the small amount of the adjustment you plan to make. Use the graduated markings on
the knob to mark your starting and ending points. For example, if you are already pretty close, you might try backing
off just two small graduations, or roughly 2 arcminutes. Finally, make the actual adjustment by tightening the otherknob thereby making the tiny adjustment you required and eliminating any shift because everything is already tightwhen you are finished. By using the graduations, you can easily undo any errors or estimate the magnitude of yournext adjustment.

Precision-Adjust Rotating Pier Base with Azimuth Bearing
Under normal circumstances, the Precision-Adjust Rotating Pier
Base does not require adjustment. However, you may, on rareoccasions, need to adjust these screws to gain the proper feel
during the adjustment process.

The Precision-Adjust Rotating Pier Base consists of two plates thatallow ultra-smooth adjustments for critical polar alignment. Notice
the two set screws on the front side of the Precision-Adjust Rotating
Pier Base. They are located at the “NW and NE” positions. Thesescrews are used to apply tension to the rotating plate. If you noticea slight amount of shift, particularly with a larger scope, carefullytighten the screws a small amount. DO NOT overtighten! If you find
too much resistance, then loosen the screws slightly.

TensionAdjustment Screws

Using Software to Improve Pointing Accuracy

Software solutions are available today that will help to compensate for orthogonal problems as well as other idiosyncrasies
of your telescope, mount and optics. These programs analyze and compensate for these problems, resulting in improved
telescope pointing performance.
●

Astro-Physics Command Center (APCC), Pro version with pointing and tracking model, www.astro-physics.com●

MaxPoint™ Modeling Software from Diffraction Limited, www.cyanogen.com●

TPoint™ Modeling Software from Software Bisque, www.bisque.com

34

MISCELLANEOUS ITEMS
Lanyard Post and Bubble Level

We have added a Lanyard Post on each side of the
1100GTO mount. Its purpose is to provide a convenient
place to hang the Keypad lanyard during an observing
session. The added bubble level will make it easier whensetting up and leveling the mount. See photo at right.

Bubble Level

Lanyard
Post

Warning for Dec. Servo Cable

One of the most important things to remember when disassembling the1100GTO for transport is to disconnect the Dec. Servo Cable before
separating the two axes. We all need a reminder from time to time andso we have posted a decal on the Dec. axis reminding you not to forget
to disconnect it. See photo at left.

SLEWING YOUR MOUNT IN BELOW FREEZING TEMPERATURES
There are several potential problems when slewing your mount in below freezing temperatures. The symptoms are awavering or chattering sound from the motors, a slowing down of the slewing with a sudden jolting stop at the end of theslew, and in the worst case, a continuous running of the motors and loss of control. The following are four suggestions toalleviate the problem:●

First, in cold weather it takes significantly more power to slew the motors than it does in the summer. This extra
current drain can cause a voltage drop in the power cord running from the supply to the GTOCPx control box. It istherefore especially important that you not use extension cords between the mount’s cord and the DC power source.
If you must have a long distance between the supply and GTOCPx control box (unavoidable in some observatory
situations), use a heavy wire to minimize the voltage drop.
If the power drops below about 10.5 - 11 volts at the servo terminal, the internal computer chips may reset withsubsequent loss of control of the motors. If your supply is marginal, it may also not produce the voltage necessary forproper operation during slews. It is a good idea to limit the slew speed to 600x during real cold weather to reduce thepower demand from the supply.

●

Second, it is very important to have a properly set worm mesh and to not have it set overly tight. One symptom of an
overly tight worm is a chattering sound as the motors try to slew at 1200x or even as low as 600x. You can check to
see if the worm turns easily by removing the motor covers and then rotating the large aluminum spur gear. Try turning
it by hand one full turn in each direction. If it does not easily turn, then the motor will also have a difficult time turning
it. Check in our technical section of the AP web site to learn how to set the worm mesh.

●

Third, under extreme cold temperature conditions (below -20F) it may be necessary to replace the grease on the worm
wheel teeth with a lighter material. We are currently using a custom mixed grease which has a very wide temperature
range and promises to be effective even during these cold temperatures. We have Grease Kits available. We have
tried straight low temperature greases that work to -80F, but in each case the worm gears get abraded very quickly.

●

Fourth, we recommend using a 15-16 volt power supply (or equivalent) for heavier loads. We have found that thehigher voltage improves motor performance when operating under these adverse conditions. Do not exceed 16 volts.

35

ORTHOGONALITY CORRECTION

Accurate GoTos require good polar alignment and minimum orthogonality. Orthogonality errors will cause pointing issues
with German equatorial mounts, especially seen when doing a meridian flip that makes the pointing accuracy much worse.
Traditionally, correcting orthogonality (sometimes called “cone error”) involves meridian delays and flipping back and forthacross the meridian to observe how far from image center that the star falls. This is time consuming and involves trying
to remember whether you need to advance or delay the flip time in order to swap sides. Is it east side or west side?...
advance or delay?...groan!

Er

ro

r

D
Po irec
C la tioel r A n
es x otia is fl P an
ol d
e

al

West

Direction of the
Celestial North Pole

on

N

Error

Non-Orthogonality

og

N

Direction of the
Celestial North Polerth

Non-Orthogonality

O

2x Erroron-Orthog
fN

ality
on

Path
o

Here is a faster method that won’t make your head spin.

East

West

East

Step by step (mechanical correction)●

Do a GoTo to Polaris. The star will not be in the center (eyepiece or CCD image) if you have any orthogonality error.

●

Put the star as close to center in Dec. with the N-S buttons. You will find that it will not move with R.A. with the E-W
buttons.

●

Push a bit on the telescope tube in the R.A. direction, you will see the star move either toward or away from the center.

●

Determine which way the tube must move to end up toward the center.

●

Loosen either front or rear scope ring attachment to the dovetail plate and slip a thin shim under the rings (.005” to.025” as needed).

With the right amount of shim, you can get Polaris exactly in the middle in the R.A. direction while using the N-S buttons toadjust the Dec. direction. You’ll be able to go from one side of the meridian to the other and put every object on the chip orin the eyepiece. Elapsed time...about 10 minutes!

APCC Pro Software
Orthogonality and polar misalignment can also be corrected by using the Poining and Tracking Modeling found in APCC
Pro version. It is always advised to minimize these errors mechanically before making the APCC model. Please reference
APCC features and information found on the Astro-Physics website.

36

1100GTO-AE AND 1100GTO-AEL ABSOLUTE ENCODERSThe Absolute Encoder option for the 1100GTO mount can be installed at the factory before shipping or installed later by theuser. It provides absolute positioning information, eliminates periodic error and eliminates Dec. backlash. The encoders
provide the ultimate in mount perfection.

When the encoders are installed at the factory they are shipped with the encodrs turned on!
There is no reason to ever turn them off!

Additional Parts Included with the Absolute Encoders●

R.A. and Dec. RESA Ring Assemblies, installed●

R.A. and Dec. Readhead Assemblies, installed●

Cable from GTOCP4 Control Box to Interface at rear of the R.A. axis (CAB16AE)●

Screw driver, 1/8” flat (FSDF18)

If you purchased the kit to install the encoders yourself, you will also recieve fasteners and complete instructions.

Absolute Encoder Cable Connections

There is only one external cable (CAB16AE) with its two connectors. This cable connects at the rear plate of the R.A. axis
(slot screwdriver required) and runs to the Encoder connector on the GTOCP4 Control Box.
The two photos identify both the Servo Motor cable and the Absolute Encoder cable and their respective connections.

to CP4
Encoder

Absolute Encoder
Cable

to CP4MotorsServo Motor
Cable

to RA
Motor Box
to DecMotor Box

If one orders the Absolute Encoder Kit to be installed on an existing mount, then each Readhead (R.A. and Dec.) will haveinternal connectors requiring a one-time connection. This will be described in full in the instruction guide that comes withthe kit.

Benefits of Absolute Encoders Summary

The utility of absolute encoders varies from brand to brand. Some manufacturers make very limited use of encoders anduse relative (not absolute) encoders to provide a potential benefit to tracking and nothing else. The benefits inherent to theMach2GTO with its premium dual on-axis absolute encoders include:●

The mount always knows where it is pointed regardless of power loss, movement of the axes when the power is off,bumping the mount or wind movement.

●

Homing positions can be set to whatever orientation a user wants, without limitation.

●

No re-homing is required for remote locations should there be a power loss.

●

Periodic error is fully corrected. No need for occasional PE measurement curves.

●

Zero backlash in Dec. axis for precision guiding.

37

●

Dual-axis absolute encoders allow for variable tracking that automatically adjusts for refraction parameters.

●

Very accurate pointing makes it easy to find very faint objects.

●

Very precise tracking such that unguided imaging may be accomplished with an appropriate optical/imaging setup.

●

Very precise guiding, if needed, with instant response in both axes. Guiding is only needed to correct for optical/
imaging train issues, not mount issues.

●

The dual-axis encoders enable the mount axes to accurately respond to your guider software commands down to the
1/10 arc sec level. There is no periodic error to fight; there is no Dec backlash delay to overcome.

●Corrects for polar misalignment and repeatable mechanical flexure.

●

Very precise dual-axis tracking is very important for high-precision tracking on objects like comets, asteroids, andartificial satellites, where the mount uses a “self-guiding” function based on orbital elements.

●

Although absolute encoders cannot anticipate wind, they can react to it after the fact. So, you will have excursions but
the axis being affected will recover much faster when the encoders are on. The best strategy is to set your mount low
to the ground without extending the tripod legs. Large telescope tubes catch more wind then skinny ones. Same withshort scopes versus long ones.

38

QUICK START SUMMARY – NEW INSTALLATIONS USINGKEYPADSThis summary gives an outline of the workflow to have a successful first observing session. Enjoy!
1. Enter the Time and Location data into the Keypad. Follow the instructions in the Keypad Manual for entering your Timeand Location data into the Keypad. (Location 1 is usually your primary observing location)
2. Set the Keypad to AutoConnect: NO. This will allow you to choose the location for which you entered the data above.
Remember to power cycle the mount after the data has been entered. This will lock the information.
3. Assemble the mount. Reference this mount manual.
4. Balance the system. Reference this mount manual.
5. Polar align the mount – at least roughly. (If using the daytime routine, move this step to after the mount is initialized. If
using the RAPAS, do it before initializing.)
6. Place the system into a pre-defined AP Park position for initialization. Reference the positions shown at the end of thisQuick Start Guide.
7. Power up the mount; select your location and press GoTo.
8. The next menu has 4 choices. Choose “4=New Setup” and select the Park position that you chose in #6 above. This
will initialize the mount and ready it for going to your first object.
9. When you arrive at your first object you may need to use the N S E W buttons to center the object. Do so and thenpress the RA DEC REV button on the bottom right, followed by the #9 button to do a ReCal of position. The following
GoTo slews to other objects should be more accurate.
10. After finishing your night’s observing (or day’s solar observing) it is best to park the mount into your chosen Park position by pressing 2=Setup; then 4=Park / Mount Opt.; and finally choosing the Park position number where you wish topark.
11. Power down the mount.

Helpful Hints●“New Setup” is only used when you are setting up the mount for the first time or if you have readjusted scope position
via the clutches and wish to restart from a “Reference Position”.

●“ResumeLastPosition” is used when you parked the mount at the end of the previous session and wish to begin a newnight of observing. Selecting it will initialize the mount and you’ll be ready to go to your first object.

●

If you are in a permanent setup, then you should set the Keypad to “AutoConnect: YES” so that when you power up
the mount, it will automatically be initialized and ready to go to your first object. This is the most automated of the
setups using the Keypad.

What If I Get Lost?
Hope is not gone...there are a couple very quick and easy fixes!

Manual Fix (when with the mount)
1. Loosen all the R.A. and Dec. clutches so that the scope can be moved freely with your hands. Moving the scope into a
Park 3 position will provide additional safety for this procedure.
2. Command the mount to go to Park 3 using either the Keypad or a computer (whichever you have been using for theevening). While the motors are moving, hold the scope with your hands so that it remains safe.
3. When the motors both stop, use your hands and put the scope into Park 3 (use your eyes to get close) and then tighten
all the clutches.

39

1. That’s it...you’re done! Orientation has been restored to the universe! When you go to your first object you’ll need to
tweak the centering and do a ReCal, but you’ll be close.

Remote Fix (requires APCC)
1. Park mount in Park 3 position and click the Home/Limits tab or AE tab (if absolute encoder mount)
This must be done when setting up the mount and when it is calibrated with the night sky.
2. Home/Limits Tab: Click the Configure Home and Limits button and choose Current APCC Park Positionbox (recommended) and click Set Home Position button.
This establishes mount gear angle and will allow “lost” mount to be recovered even through power cycles.
3. AE Tab (Absolute Encoder Mounts): Click the Configure Home button (under Find Home) and follow instructions. In
the Configure AE Home window that appears after the Calibration warning it is recommended to choose the Current
APCC Park Position (Park 3 is recommended). Continue following the instructions.
4. If the mount becomes “lost”, then clicking the Find Home button will send the mount to the established Park 3 Home
position and recalibrate the mount. You will then be able to continue your night’s observing.

Important Note: Once the above Home Positions have been set you MUST NOT loosen the clutches
and move the mount by hand. If that is done, then the Home positions will need to be re-done!

QUICK START SUMMARY – NEW INSTALLATIONS USINGCOMPUTERSThis summary gives an outline of the workflow to have a successful first observing session. Enjoy!
1. Install and set up your control software and drivers. This can be done before you even take delivery of your mount.
a) Set up ASCOM and the drivers first. You will find the URLs for them below and links on the Software Support pageof our website. It is very important the you download the latest versions.
i)

FTDI driver - http://www.ftdichip.com/Drivers/VCP.htm This is required for the USB funciton of the GTOCP4.

ii) ASCOM Platform - ascom-standards.orgiii) AP V2 ASCOM driver - http://www.gralak.com/apdriverb) Install third party software (Starry Night, TheSkyX, MaxImDL, etc.)c) Adjust software settings - follow the appropriate workflow documentation in the GTOCP4 manual.
d) If using the Keypad along with a computer, set the Keypad to AutoConnect=EXT and power cycle the mount inorder to lock in the change.
2. Assemble the mount and add the mounting plate, counterweights, telescope and other accessories.
3. Balance the system per the guidelines earlier in this manual.
4. Polar align the mount – at least roughly. (If using the daytime routine, move this step to after the mount is initialized. If
using the RAPAS, do it before initializing.)
5. Place the system into a pre-defined AP Park position for initialization. .
6. Power up the mount and connect with your primary control software. Use the primary control software to initialize
the mount. Start out from the park position chosen in #5 above. Your other initialization settings will have been set
already in step #1.
a) If using APCC, always start it and connect with it first.

40a) If the AP V2 Driver is your primary control software, it must be started with a client program.
1. Connect other software that you will use with the mount.
2. After finishing your night’s observing (or day’s solar observing) it is best to park the mount into your chosen Park position using either the AP V2 driver or APCC, rather than Third Party software if you are using a PC for mount control.
3. Power down the mount.

41

AUTO-ADJUSTING GEARBOX - NO MORE WORM MESHING!
The good news is that your mount is always in mesh, thanks to the Auto-Adjusting Motor Gearboxes! The 1100GTO mountrepresents a new era in the ease of gearbox adjustment. Our new design eliminates the need for gear mesh adjusting. It
has become automatic. Spring pressure holds the worm screw in perfect mesh with the worm wheel at all times.
The only adjustment that may ever need to be made is to re-set a backstop...and that is rarely needed if ever.

Checking and Adjusting the Gearbox Backstops in R.A. and Dec.
This is a very easy and quick process. It is also a process that you should almost never need to do. Many mounts will go
several years or longer without the need to tweak this backstop. Adjusting this backstop is about the only way that you canactually mess up your gear mesh. So, approach with caution. (Tool needed: 5/64” hex key)
1. Put the mount into a Park 3 position. This is important to ensure that there is not uneven pressure on the gears due
to an out of balance load. Be sure that the mount is powered off. Park 3 is counterweight shaft down and scope in linewith the R.A. axis, pointing toward the pole.
2. Remove the Lever Assembly Cover. Grip the cover and pull it straight out.
3. Make sure the lever is in its normal position - snapped in place, parallel to the respective axis.
4. Loosen the Lever Assembly screws. Using a 5/64” or 7/64” hex key, loosen the two screws (#1 in the illustration) sothat the assembly is freed to move. This should require less than one turn of each screw.
5. Apply a slight pressure to the lever assembly. Using your index finger and thumb as shown, apply a very gentle
pinching pressure to shift the assembly towards your thumb (the backstop only needs to touch). This sets the properbackstop position.
Important: Do Not push on the gear box itself when adjusting the backstop. Pressing on the rear of the box can cause
the box to pivot out of mesh and give a bad adjustment. Pressing on the top of the box will push the box into tighter
mesh and would cause excessive tightness and damage to the worm wheel teeth.
6. Tighten the screws. While maintaining the slight pinching pressure, snug and then tighten both screws.
Do Not Overtighten.
7. Replace the Lever Cover. Replace the cover and you are finished. It is that simple!
8. Repeat with the other axis. Repeat the process with the other axis, if necessary.

1

RemoveLever Assembly
Cover

1

42

What to do if you believe that there is a backlash in the gearbox●●

First if you think that there is a worm gear mesh issue, you are probably wrong. If you think there is backlash, it isalmost certainly from a different source, so look elsewhere first.
○

Check the mesh of the spur gear reduction set. With your thumb and forefinger gently attempt to move themiddle spur gear back and forth. There should be a slight amount of movement so that the gears do not bindup; however, it should be slight. If there seems to be too much looseness, contact Astro-Physics for further
help.

○

Check to be sure that the two shoulder bolts that secure the spur gears are snug. Important: the bolts should
be snug...Do Not Overtighten, as they can break or damage the gears.

○

Check that the entire motor/gearbox is securely fastened to the axis housing. There should be a very small
amount of front-to-back rocking that is possible due to the spring loading mechanism, but there should be no
discernible side-to-side movement. If you feel side-to-side play, contact Astro-Physics

IMPORTANT! Do the following with the mount powered ON. It should be UNPARKED and tracking should be
STOPPED. There are two or three small screws securing the worm spur gear to the worm. A screw may be obscuredby the top gear. For that reason the mount is powered on so that you can rotate the gear using the direction buttons at
12X or 64X. If you would attempt to turn the R.A. gears by hand, you would lose your PE correction; therefore use thedirection buttons.
○

Check that the worm’s spur gear is securely attached to the worm shaft. The 2 screws must be tight. (Becareful, however! They are small screws, not automotive lug nuts!)

Worm SpurGear Screws (2)Worm SpurGear Screws (3)43SOME IMPORTANT NOTES●When using Mounts with Auto-Adjust Motor Gearboxes:○

Use the clutches when repositioning the mount! This is a safer practice than using the gearbox
disengagement lever in order to ensure that the gear teeth are not damaged by accident. Refer to yourmanual for clutch operation.

○

Begin your balance procedure in Park 3 position (pointing to the pole). This will ensure that an out ofbalance scope does not have a sudden, wild swing that could damage the scope, the mount or you!

○

Be sure that the Gearbox engage/disengage lever is fully disengaged and that the worm isfully separated from the worm wheel when balancing the mount (or moving the mount whenrepositioning)! It is important not to damage the tops of the gears by bumping the worm and worm wheel
teeth!

●

Be careful not to twist and inadvertently damage internal cables. It is important to remember not to twist anddamage internal cables by over-rotating the axes. If the axes are rotated when setting up or performing mount
maintenance, you will need to undo the axis rotation to return cables to their normal position. Internal cables should
not be pulled tight; rather, they should be left slack and free to move.

●

Be sure that all fasteners on the mount and scope are tight. You do not want to have to catch a falling scope or
see it sitting unexpectedly on the concrete!

●Computer and Keypad use together. If you are using a computer for primary mount control, but wish to havethe Keypad connected for convenience while at an eyepiece, then set the Keypad to AutoConnect: EXT so that thecomputer will initialize the mount, not the Keypad.

●

Always Initialize and park the mount using the same device. If you initialize with the Keypad, then park with
the Keypad...if you initialize with the computer, then park with the computer. Important Note: If the Keypad is yourchosen method of operation, then uncheck the following two boxes in the AP V2 driver’s Setup Telescope...1- Sync
Mount to PC Time and 2- Keep Mount Time Synced to PC Time.

●

Unpark from Last Parked. If the mount is being re-started from a previous night, as in a permanent observatory or ata week-long star party, then unpark from Last Parked (assuming that the scope has not been repositioned manually byhand via the clutches since it was last parked).

●

Unpark from a defined park position. If your equipment is being set up afresh for a night’s observing, then place
the scope in a defined park position and have it unpark from that specific position. If it is to remain set up for the nextnight, then park it to your position of choice and resume from Last Parked the next night.

●

GTOCP4 Control Box will auto-park mount when powered off. The GTOCP4 control box will auto-park the mountin place when the power is turned off or is interrupted. Nevertheless, we do recommend parking the mount to aconvenient park position when finishing the evening’s viewing (and leaving the mount set up for another night).

●

Use the mount with its own power supply. For best performance the mount should have its own power supply.
This is especially true when imaging.

●

Reference the Astro-Physics Technical Support page of the website. There is a wealth of information on theTechnical Support page that can often answer the questions that you have, as well as provide in-depth understanding
and fixes. All the latest versions of the manuals can be found on the page.

●

Remember that the answer to most questions can be found in the supplied manuals or on the website. Pleasereference these manuals or the website Technical Support before calling Astro-Physics. If you cannot find the answer,
then the Technical Support team is ready to help.

Please take special notice:●

Outdoor Storage – If you have a mount that is left outside for extended periods covered by a tarp or scope cover,●

VERY IMPORTANT: We take every precaution to make our control boxes moisture and dew resistant; however,they are not waterproof! We cannot be responsible for water damage when reasonable care has not been taken toshield them from excessive dew or when storing them outside under tarps for extended periods.

then it is highly recommended to remove the GTOCP4 and Keypad and take them inside to a safer environment.
Tarps and covers cause significant condensation build up unless steps are taken to mediate the problem. Often low
wattage light bulbs or fans are used to reduce condensation for short term storage, but this is no guaranty.

44

MOUNT CARE, CLEANING AND MAINTENANCE
Like any fine piece of equipment, your mount’s longevity and performance are directly correlated with the quality of thecare that you give it. Handle it with respect, keep it as clean and dry as is practical, and perform a few minor maintenancetasks, and your 1100GTO will give you many years of trouble free service.

Care

Although we build it to be rugged enough for field use, your 1100GTO is a precision instrument with very accurate worm
and wheel adjustments. Please be careful if you place the mount on a flat surface, i.e. the ground or trunk of your car. The
gear alignment may be affected if the R.A. and Dec. Motor / Gear Box assemblies sustain undue lateral force. This is trueof any fine instrument. We suggest that you transport and store the mount in a case or in a well-padded box. ALWAYS
disassemble the mount before moving it or transporting it. More damage can be done in a few careless seconds in transit
than in many hours of normal operation.
Try to keep your mount protected from dust and moisture when not in use. In warm, humid weather, be aware of the dew
that may have formed on the mount while in the field and allow the mount to dry out before packing it away for storage
once you get home. On the other hand, if it is cold and dry outside, keep the mount packed up when you bring it into thehouse until it reaches room temperature to avoid “fogging it up.” (The same advice applies to telescopes, eyepieces andother equipment in your Astro-arsenal.)

Cleaning and Touch-up

Wipe your mount clean with a soft dry cloth. If needed, you can use a damp cloth or a cloth that has been sprayed with amild, non-abrasive cleaner (window or all purpose cleaner – no bleach). Do not spray cleaners directly onto your mount.
If you use a cleaning product, follow with a damp cloth to remove the chemicals from the mount.
The painted surfaces of your mount may end up with scuff marks from repeated transport and assembly / disassembly.
Most of the time, these marks can be removed with a product like Color Back™ by Turtlewax™ (automotive product).
Simply apply with a paper towel and buff out the mark. If your paint becomes chipped, touch-up kits are available forpurchase – please call us.
NOTE: Paint touch-up kits can only be sold to U.S. customers due to regulations governing shipment of hazardous
materials.

Counterweight Appearance

Stainless steel is resistant to oxidation, but over time its appearance can degrade. Applying a good car wax coating will
help to maintain the pristine stainless steel finish of your counterweights.
Should cleaning need to be done, it is recommended to use an SOS detergent pad to clean the weights. Be sure to dry
them thoroughly, and then follow up with the car wax.

Routine Mount Maintenance

Under normal operating conditions, minimal maintenance is required. If the R.A. and Dec. axes are attached together for along time in outside conditions (i.e. in a permanent observatory) then the mating surfaces should be lightly oiled or greased- if you expect to get them apart again after 10 years.
Jostling and vibrations associated with transport to and from observing sites has had the effect of causing screws andfasteners to work their way loose over time. We have worked very hard in both the design and assembly of our mounts toalleviate this problem, but it is still a good idea to periodically (once or twice a year) inspect and if necessary re-tighten any
easily accessible fasteners. Additional maintenance information can be found below in the troubleshooting section and in
the Technical Support Section of our Web site.

Worm Wheel MaintenanceUsing the entire worm wheel ensures even wear and extended life. Under normal use the mount moves back and forthusing only one half of the worm wheel...the other half is not used.
Here’s what to do: Send the mount to Park 1, unlock the clutches and push the mount to Park 4. Lock the clutches andthen power cycle the mount (power off and then on). Tell the mount to resume from Park 4. The mount will then be using45

the other half of the worm wheel.
Note that it will be necessary to have the Keypad set to AutoConnect=NO (if initializing with the Keypad) or to set the AP
V2 driver / APCC (if initializing from the computer) to Unpark from Park 4. Once this operation is done remember to reset
to Unpark from Last Parked.
Do it twice a year…that should be enough.
IMPORTANT! If you have an encoder mount, you MUST reestablish your Home and Limits.

Greasing Mount

We have designed access ports for periodic greasing into the1100GTO. One is located on each axis. By opening the port,
you’ll be able remove the old grease using a toothbrush and soft
cloth to brush and wipe away the grease while turning the axis to
fully reach the entire gear. The gear wheel can be advanced toanother section by simply moving the mount east or west at slew
speeds via the directional buttons. Similarly, the new grease canbe applied by brushing it into the gear while turning the axis.
All 360 degrees of the worm can be accessed that way, even withthe mount fully loaded with counterweights and telescopes. No
need to tear down a permanent setup to do this maintenance.
Contact our office for a Grease Kit (GREASEM) of custom mixed greases. Frequency for greasing will depend on mountuse and environment. Greasing every year or two will maintain your mount for life.

TROUBLESHOOTING, TIPS AND SUPPORT
Troubleshooting and Tips

Additional troubleshooting questions are in the GTO Keypad or GTO Servo System manuals. Some of the issues
discussed in these manuals relate to mount communication issues whether you use the keypad or control the mount with aplanetarium program or PulseGuide™. Please refer to them.

The Declination (or R.A.) axis does not turn freely, even with the clutch knobs fully loosened.
The design of the clutches is such that spring loaded tips always maintain some friction against the worm wheel.
Consequently, the axes will never spin freely. Back the clutch knobs off by at least two or three full turns to more fully
disengage the clutches. There will always be some friction. The 1100GTO clutches can be fully tightened without worry.

The LED on the GTOCP4 Control Box changes from red to yellow and the motors stop or go out completely (for control boxes shipped after 02-25-00).
1.

The voltage of your battery has probably gone below 10.5 volts.

2. The current rating of your AC-DC power supply is too low.
Note: The most common problems are due to inadequate power supply! Voltage must be measured while under load.
Additional explanation: During slewing under load, the two motors draw up to 3 amps from a 12-volt source. This may
increase when the temperature approaches freezing or below. It is recommended that your supply be rated at a minimum of 12 volts DC at 5 amps continuous. 12.3 to 16 volts with a capacity of 5 to 10 amps is recommended for best
performance. (Do NOT exceed a nominal 18 volt system.) See the Power Considerations section beginning on page29)
If you also power other equipment (CCD cameras, dew heaters, etc.) from the same source (NOT recommended!), youwill need a supply capable of up to 10 amps. The more equipment you have, the more current capability you will need.
We always recommend giving the mount its own supply and using additional supplies for other equipment.
For portable applications, we recommend heavy-duty deep-cycle batteries designed for deep discharge applications

46

(i.e. marine, golf cart, fork lift, or wheel chair batteries).
3. The motors are overloaded, probably due to an unbalanced load on your mount.
Rebalance your telescope, and then press one of the N-S-E-W buttons to reset the keypad. Re-enter the last object
on your keypad and the scope will slew to the correct position. Even though your motors had stopped, the logic in thecontrol box retained the scope position in memory. As long as you didn’t change the pointing position of the scope, you
are still calibrated.
If the scope was moved during re-balancing, simply enter a nearby bright star on the hand controller, press GOTO andallow the mount to finish slewing. You can then move the scope manually or with the N-S-E-W buttons to center thestar in the eyepiece, and press the #9 RECAL button. This will recalibrate the mount.
Additional explanation: The GTO drive circuit includes logic for overload protection to prevent burning out the expensive servomotors in case of severe overload on the two axes. The primary cause is an unbalanced load in R.A. If theextra load opposes the motor rotation, the motor must work harder to track at the sidereal rate and the current will rise
to high levels. If the current exceeds the trip point for more than a minute, the logic will shut the motor off and tracking
stops. It typically takes about 4 lb. of unbalance to trip the overload, but a very heavy load of scopes, accessories andcounterweights on the mount can decrease this unbalance threshold.

The keypad reset (or locked up) when I plugged my CCD camera, PC (or other equipment) into the same
battery as the GTO mount was using. The battery has a meter, which shows 12V.
The meter is reading an average and will not show dips. Gel cells have internal resistance, which will cause voltage dropwhen the load changes. When you connect an additional CCD camera and PC the load will drop below 9 volts and the
keypad will reset or it may affect the GTO circuit itself and cause the keypad to lock up.
We recommend that you use a large marine battery that is not a gel cell and hook everything up to it before calibrating the
GTO. Or, better yet, put the other equipment on a separate battery.

What is the maximum voltage that I can use to power the servo drive?
Please refer to the Power Considerations section of the GTO Servo Drive System manual.

For polar alignment, I am using declination drift technique with stars on east & south. Now, I do not see
any drifts in declination on both sites (E & S), so the mount “should” be properly aligned. However, I
have still small drift in R.A. which looks like the R.A. motor is a bit faster than earth rotation. This drift
is something like 1.5 arcseconds during 1 minute or so & accumulates over time, so it doesn’t look likeperiodic error.
The sidereal tracking rate is exact in the mount (it is crystal controlled and checked here for accuracy). However, the stars
do not move at exactly the sidereal rate everywhere in the sky. The only place they move at that rate is straight overhead.
As soon as you depart from that point in the sky, the stars will be moving more slowly, especially as you approach thehorizons. Thus, it looks like the mount is moving slightly faster than the sidereal rate. Just because you have done aclassic drift alignment, does not mean that the stars will now be moving at the sidereal rate everywhere in the sky.
In order to increase the area of sky from the zenith that will give you fairly good tracking, you will need to offset the polar
axis by a small amount. The amount will depend on what your latitude is. The other approach is to vary the tracking rate
for different parts of the sky. Ray Gralak’s Pulse Guide will allow you to dial in an exact tracking rate for any part of the sky.
The Astro-Physics Command Center Pro (APCC) includes tracking and pointing correction based on calculations fromatmospheric refraction all the way up to sophisticated real-world models based on plate-solve data for your specificinstrument package.

Initially, the mount was working fine. Then, suddenly the mount stopped tracking altogether!
Chances are that the motor was turning properly and driving the worm gear, but that your clutches might have been loose
and therefore the scope was not following the motion of the worm gear. The fact that the high slew rate did move thescope does not change this, because Roland has seen this himself where the tracking rate did not overcome the slipping
clutches but the slew rate did.
If you are unsure of the motion of the motor, just remove the motor cover plate and look inside. You will see the motor

47

turning. Sometimes when you have the clutches loosely engaged and the counterweights are somewhat out of balance,
being heavy in the east, then the clutches might slip at the slow sidereal rate.
In any case, just to set your mind at ease, simply remove the motor cover next time something like this happens andlook at the motor shaft. If the motor is not turning, you will have some kind of electrical problem. If it is turning, then it ismechanical.

The motors sound louder and more labored in cold weather.
As the temperature drops, we recommend that you reduce your slewing speed to the slowest slew rate. The cold causes
the lubricants to get stiff in the gearboxes. This can make the high-speed gears resonate and sound screechy. Lowering
the slew speed in winter will eliminate or reduce this. You might also want to add a drop or two of light machine oil to thecenter posts of the individual gears. Just remove the cover on the gearbox and add the oil drops. The noise is nothing toworry about. Refer to the section of this manual entitled: Slewing Your Mount in Below Freezing Temperatures.

The declination axis does not appear to be moving properly. How can I check it?
Please refer to the section of this manual entitled: “Characterizing the Dec. Axis Motions,” which explains how to use
Diffraction Limited’s Maxim DL™ software to characterize your mount’s performance.

When I press the E button on my keypad, it takes forever for the star to finally stop.
First, the problem is most often caused by the worm and worm wheel not being in mesh (this is often the case when aused mount is purchased and the previous owner never ever adjusted the worm mesh or the mesh was altered during
shipment). When the worm is out of mesh, it takes the motor many seconds to reverse the tooth contact from leading totrailing edge because it is running at the very slow sidereal rate. Backlash adjustment is very easy to accomplish on the
1100GTO that has the Auto Adjusting Motor Gearboxes. Please refer to the section in this manual entitled: “Gear Mesh in
the 1100GTO”.

I am experiencing trailed stars after a slew and apparently a high, variable backlash.
Check to make sure that the spur gear that is attached to the end of the worm is not loose. A loose screw will indeed
cause the axis to delay during reversal. In a few cases, we have seen that the set screw on this spur has backed off andneeds to be retightened. If you have any doubts about where this worm and spur gear is in the scheme of things, call
Astro-Physics and we will talk you through the procedure to check this.
Remember this: Any backlash or looseness in Dec. will NOT cause trailed stars after a slew. That is because the Dec. axis
does not move once it gets to its new position, so no trailing is possible. So, if you are getting trailed stars for a short time,
don’t look for something in the Dec. axis.
However, the R.A. Axis WILL cause trailed stars after a slew if the spur gear is loose. That is because this axis must moveat the sidereal rate immediately after getting to the new position. If the spur gear is loose on the worm shaft, it will turnslowly at the sidereal rate without imparting this motion to the worm itself (because it is slipping). At some point, the set
screw will catch on the edge of the flat on the worm shaft and begin to drive the worm gear. So, this looks like classicalbacklash, when in fact it is not backlash at all, and all attempts at setting the gear mesh on the worm are futile to correct
this lost motion.
When we get a chance, we will post a complete set of pictures on our website showing how to check for this loose gear
condition. Meanwhile, you can take the cover off the motor gearbox and acquaint yourself with the spur gears inside. Do
not be afraid to move and wiggle things by hand to see how stuff works.
One more thing, sometimes a person will be absolutely certain that it is the Dec. axis that is giving him a problem because
the CCD program he is using shows some improper function in the Y-axis, and he is absolutely certain that Y = Dec. Aftermuch sending of equipment back and forth to our facility, it finally is determined that it was the other axis after all that
had the problem. PLEASE, please make sure that you have identified the proper axis. In the case of any kind of motion
problem like this, it would be really helpful if you removed your camera, inserted an eyepiece with crosshairs and actuallylooked to see what was happening. You can then identify exactly which direction, R.A. or Dec., is moving after a slew.
Sometimes because of mix-ups in the CCD software (MaxImDL™, for instance), the axes are identified backwards.
When you are trouble shooting, remember, R.A. is the only axis that must move at the sidereal rate and is the only axis
that can trail a star if it is not moving correctly at that rate. The Dec. axis does not move after a slew and will not trail astar except by a very slow long period drift due to polar misalignment, etc. It will not trail a star image EVEN if it has 10
degrees of backlash, so that analysis is definitely suspect.

48

I’m having a frustrating guiding problem with my mount and need to figure out my next steps.
To begin with, the directions represented by the X+, X−, Y+ and Y− in your guiding software do not necessarily correspondto any given cardinal directions. To the guiding software, “X” and “Y” simply refer to the rows and columns of pixels on theguide chip – nothing more.
The act of calibration tells the guiding software how to relate a guide star’s drift along the columns and rows to movedirections in the mount, but it does not make it so that X is necessarily always right ascension and Y always declination.
To further complicate this, each time you alter the camera’s orientation, you effectively change the relationship between X /Y and R.A. / Dec.
Your very first step in diagnosing any type of guiding problem should be to determine the actual current relationshipbetween the X and Y of the guiding software and the R.A. and Dec. of your mount. This is easily done in your guiding
software by making a manual move in one axis during an exposure and comparing this to a guide move from the keypad(use the keypad – not your computer software!) where you know the axis and direction for certain.
We have seen customers waste countless hours (not to mention dollars) in trying to fix a guiding problem on an axis thatwas performing perfectly. Meanwhile, their true problem remained, all because of this axis mix-up.
Your next step would be to remove the camera and place a high power eyepiece with crosshair reticle into the focuser.
Then sit down and watch what happens to the guide star. With the eyepiece and reticle, you can see whether or not themount is tracking smoothly and how the periodic error is manifesting itself. Yes, you will have periodic error, and any good
CCD camera will pick it up to give you oval stars - that is a given. What you need to find out is whether this periodic error
is within limits (± 3.5 arcseconds for the 900GTO and 1100GTO and ± 2.5 arcseconds for the 1200GTO and 1600GTO)
and whether it is smoothly varying. You can also do some hand guiding using the 4 buttons on the keypad. It will tell you
how responsive the mount is to your guiding inputs and may even show some hidden problems when you try to keep thestar on the crosshairs.
Alternately, you can use PEMPro™ (The full version of PEMPro™ is included with the 1100GTO) to characterize yourperiodic error. It will tell you things like the peak value and the smoothness of the error.
You can also characterize your mount tracking and guiding abilities using the “Characterizing the Dec. Motions” test
outlined in the Technical Support section of our AP website and included in the back of this manual. Many times a problem
guiding in R.A. can be the result of a Dec. axis mechanical problem. Not knowing this, you will be forever chasing down
the problem on the R.A. axis, and never reaching a solution. Characterizing your Dec. Axis will at least show you that themount reacts properly to the 4 guide directions. If it shows a problem area, then at least we will know how to fix it.
Once you know that the mount is tracking in a normal fashion with normal periodic error profile, you can go from there to
begin setting up your guiding parameters. It is not a piece of cake to get an autoguider to work flawlessly. It is an art, but
once you know that the mount responds properly to the guide inputs, it should be possible to set it up to work accurately.

Additional Support

For additional information regarding the 1100GTO, refer to the Technical Support Section of our website. We also
encourage you to participate in the ap-gto Yahoo user group. The members of this group are very knowledgeable about
the operation of their mounts, CCD imaging and other related issues. The staff of Astro-Physics also participates and you
will find a wealth of information in the archives. To find the group, link from User Groups in our website’s sidebar.
If any problems occur, please don’t hesitate to contact Astro-Physics for assistance.
We encourage you to submit your technical support questions directly to Astro-Physics by phone or e-mail: support@astrophysics.com.
We may add additional troubleshooting tips to future versions of this manual or in a separate technical document. In suchan instance, we would add this information to the Technical Support section of our website as well.
ASTRO-PHYSICS, INC
11250 Forest Hills Road
Machesney Park, IL 61115
Telephone: (815)-282-1513
Fax: (815)-282-9847
support@astro-physics.com
www.astro-physics.com

49

APPENDIX A: DECLINATION AXIS BACKLASH TESTS
PulseGuide™

PulseGuide™ is a free software program, developed by Ray Gralak, to provide keypad-like functionality using a computer.
It offers the additional feature of a Dec. axis backlash test. You can download it through Ray Gralak’s website.
Once you have started the PulseGuide™ application and have connected tothe mount, go to the “PEM/other” tab and click the “Backlash Tests” button tobring up three tests suggested by Roland Christen to test the performance ofyour declination axis. Roland posted some tests that you can run on your AP
mount to see if it has a potential problem with Dec movement.
IMPORTANT: Before running tests 1 and 2 set the mount’s backlash to 0.
Also while performing the tests do not try to auto-guide.

Dec Backlash Test 1

Before starting Test 1 set up yourcamera control program (e.g.
MaxImDL™, CCDOps™, etc.) to do
a 100 second exposure (but do not
autoguide). You can also set up an autodark exposure, but make sure that you
start the test when the camera control
software is exposing the light image.
Once you start the exposure press the Start Test 1 button. With the default settings(recommended) the entire procedure will take about 90 seconds.
Test 1 will move the scope in this manner: East - pause - West - pause - East to center - North pause - South - pause - North to center.
The stars in the resulting exposure should look something like the image to the right. The scale
might be different but you should see what looks like many plus signs in the image.

If you take the image near Dec=0 the height and width will be about the same. Although notshown in this particular image the East and West points will be slightly brighter than the North/South points. This will make it easy for Roland to establish the orientation of the camera.

Dec Backlash Test 2

You will run Test 2 three times, once for each of the guiderates. Before starting this test set up your camera control
program (e.g. MaxImDL™, CCDOps™, etc.) to do a 25
second exposure but do not try to autoguide. You can also
set up an auto-dark exposure, but make sure that you start
the test when the camera control software is exposing thelight image.

1.0x

Start by setting the Guide Rate to 1x. Once you start the exposure press the Start Test 2 button.
With the default setting (recommended) the entire procedure will take about 16 seconds.
Although the scale might be different, the stars in the resulting exposure should look something
like the image shown.

0.5x

For reference the actual movement in Test 2 is: North+West - South+West - West only (the pause setting) North+West.

0.25x

Now you will need to repeat the tests at 0.50x and 0.25x. The star patterns will look similar but
smaller because the movement rate is slower. Here are two examples taken with a Traveler:50After Running Tests 1 and 2

If you see star patterns different from the above images then crop a bright star in each of the four images and save themas a high-quality JPEG. Please make sure to “stretch” each image appropriately so that it is not too dim or overexposed.
If you do not know how to stretch and create a jpeg then save the cropped image in FITS format.
Then send the 4 files (preferably zipped to save bandwidth) to Roland at: chris1011@aol.com.
After submitting these tests, AP will advise you if anything appears anomalous and if so what can be done about it.

Dec Backlash Test 3

This test moves the declination motor at regular intervals to check that thegears move properly.
To do this test you will need to remove the cover from the declination motor
housing (contact Astro-Physics for directions if you need).
The Guide Rate combo-box has 4 choices: 0.25x, 0.50x, 1.00x, and Cycle.
You can choose a specific rate or Cycle to have PulseGuide™ repeat the test
at each rate.
While watching the uncovered declination gears click the Start Test 3 button. PulseGuide™ will send 5 pulses spaced 2
seconds apart (or however many you entered in the Pulses edit box). Each pulse will of the same duration – that which
you enter in the Pulse Duration edit box. The default is 133 milliseconds. Watch carefully to make sure the pulses lookevenly timed and that the fastest moving gear moves equally each time.
Once all pulses have been sent in one direction, an equal number of pulses are sent in the reverse direction. It is normal
on reversal of direction that there is a slight delay in movement because of backlash. If this happens you may wish toincrease the pulse count. If you see erratic movement please contact Astro-Physics for instructions.

MaxImDL™
Step 1

Acquire a reasonably bright guide star and begin guiding in R.A. only - turn off Dec.
guiding. Use a 1 second or faster refresh rate so you can see the motion of the guidestar as you begin to move it around. Magnify the screen to 1600x and place the cursor
in the middle as shown. Check to make sure that the mount is guiding adequately in
R.A. and that the guide star is not bouncing around due to poor seeing. Best results
will be achieved when the R.A. guiding is 0.5 pixels average in R.A.

Step 2

Put the keypad button rate at 1.0x. Press the keypad North button until the guide starhas moved approximately 6 pixels from the center. Now press the South button invery short pulses and note which direction the star moves. It should move back toward
the middle after a few button presses. It might move slightly up or down, or it might
continue to move further away from the middle, or any combination. Please note
exactly how far, and in which direction, the guide star moves (pixel position is displayedin the guide box at right in Maxim).

Step 3Press the South keypad button until the star has moved 6 pixels off the center in the
opposite direction. Repeat Step 2 and note exactly the motion of the guide star as you
move it with the pulsed motion at 1.0x.
You may wish to enable Track Log to record the numbers for further study. Please noteon the log what you did at what time so the results will be useful later.

51

APPENDIX B: MOUNTING PLATE FASTENER CHART
A-P Part #Description

Ships with:(4) 1/4-20 x 5/8" SHCS [for mounting to 400, 900 or Mach1](4) M6-1.0 x 20mm SHCS [for mounting to 600E](4) 1/4-20 x 3/4" SHCS [for mounting to 1100, 1200, & 1600](6) 1/4-20 x 1" FHSCS [for mounting to 900, 1100, 1200 or 1600](4) 1/4-20 x 1-1/4" FHSCS [Mach1]

FP150015" Flat Plate

FP180018" Flat Plate

DOVELM2

8.5" D-style Dovetail Saddle for Losmandy D-style
Plates for 400, 600E, Mach1, 900 and 1100 Mounts

DOVEDV10

10" Dual-style Dovetail Saddle for Losmandy
D-Style and Vixen V-Style Plates for 400, 600E,
Mach1, 900 and 1100 Mounts

DOVELM162
900RP(4) 1/4-20 x 5/8" SHCS [for mounting 400 or Mach1](4) M6-1.0 x 20mm SHCS [for mounting 600E](2) 1/4-20 x 5/8" FHSCS [for mounting to 1200](4) 1/4-20 x 3/4" SHCS [for mounting to 900, 1100, 1200 or 1600][or to attach to SBD13SS or SBD16SS](4) 1/4-20 x 5/8" SHCS [for mounting 400, Mach1, 900 or 1100](4) M6-1.0 x 20mm SHCS [for mounting 600E](2) 1/4-20 x 5/8" SHCS [for special safety stop](2) 1/4-20 Nut [for special safety stop](6) 1/4-20 x 1" SHCS [for mounting to 900, 1100, 1200, 1600 or
16" D-style Dovetail Saddle for Losmandy D-style
Mach1 (M1 uses 4), or to attach to SBD13SS or SBD16SS]
Plates for 900, 1200, Mach1GTO. Also for 3600GTO(1) 1/4-20 x 3/4" FHSCS [opt. 900, 1100, 1200 or 1600 for end positions]w/ SB3622 or SB3627 Can also be mounted on AP(4) 1/4-20 x 3/4" SHCS [for SB3622 in side-by-side configuration
ring tops with blocks
and for attachment to blocks for ring-top mounting](6) 1/4-20 x 1" FHSCS [for mounting to 900 or 1100]
15" Ribbed Plate for 900 or Mach1(4) 1/4-20 x 1-1/4" FHSCS [for mounting Mach1]

1200RP15
1200RP

15" Ribbed Plate for 1200 and 1600

(6) 1/4-20 x 3/4" SHCS [for mouting to 1200 or 1600]

24" Ribbed Plate for 1200 and 1600

(6) 1/4-20 x 1" SHCS [for mounting to 1200 or 1600]

Q4047

900/Mach1 Adapter for use with DOVE08(6) 1/4-20 x 5/8" FHSCS [for mounting to 900 or 1100](4) 1/4-20 x 1" FHSCS [for mounting to Mach1]

SB08007" AP-style Sliding Bar(2) 1/4"-20 x 5/8" SHCS [for center hole in rings]

SBV08

8" V-Style Dovetail Plate(2) 1/4-20 x 5/8" SHCS [for center hole in rings](1) 1/4-20 x 3/8" SHCS [for safety stop]

SBV15

15" Wide-Profile V-Style Dovetail Plate(2) 1/4-20 x 1/2" SHCS [for center hole in rings](4) 1/4-20 x 3/4" FHSCS [for attaching directly to AP rings](1) 1/4-20 x 3/8" SHCS [for safety stop]

SBD12

12" D-Style Dovetail Plate(4) 1/4-20 x 1" low profile SHCS [for attaching the SBDAPBor LMAPBLOCKS](4) 1/4-20 x 1-1/4" FHSCS [for attaching directly to AP Rings](2) 1/4-20 x 1/2" SHCS [for center hole in rings](4) 1/4-20 x 1/2" low profile SHCS
(1) 1/4-20 x 3/8" SHCS [for Safety Stop]

SBD16(4) 1/4-20 x 3/4" SHCS [for attaching the SBDAPB Riser Blocks]
16" x 5" Wide D-style Dovetail Plate for Losmandy D(4) 1/4-20 x 1-1/4" FHSCS [for attaching directly to AP Rings]
Style Dovetail Saddles(1) 1/4-20 x 3/8" SHCS [for Safety Stop]

SBDAPBAP Riser Blocks for AP D-style Plates(4) #10-32 x 1/2" SHCS [for attaching to mounting ring tops](2) 1/4-20 x 1/2" SHCS

SBDTB
SBD13SS
SBD18SS

Adapter Blocks for Takahashi(4) M10 x 20 mm SHCS [for attaching to SBD16]

13" or 18" Side-by-Side Dovetail Plate for Losmandy
D-style Dovetail Saddles(2) 1/4-20 x 3/8" SHCS [for Safety Stops -required at both ends](1) 1/4-20 x 5/8" SHCS [for special safety stop](1) 1/4-20 Nut [for special safety stop]

SBD2V

12" Losmandy D-Style Male to Vixen V-Style Female (1) 1/4-20 x 1/4" low profile SHCS [to replace Safety Stop on V plate]
Adapter / Sliding Bar(1) 1/4-20 x 1/4" SHCS [Safety Stop for SBD2V]

LT2APM

Losmandy Tripod to Astro-Physics Mount Adapter
Plate(3) 5/16-18 x 5/8" SHCS
(4) 1/4-20 x 5/8" SHCS
(4) 1/4-20 x 1" SHCS
(3) 3/8-16 x 3/4 SHCS

CBAPT

Control Box Adapter(1) 1/4-20 x 3/4" BHSCS(1) 1/4-20 x 1" BHSCS(1) 5/16-18 x 1" BHSCS(2) 5/16-18 x 3/4" BHSCS(1) Washer 1/4"

TRAYSBTRAYSB1

Bi-Level Support Bar &Single Level Support Bar(1) 1/4-20 x 1" BHSCS(1) 5/16-18 x 1" BHSCS(1) Washer 1/4"

DOVEPW

16.5" Dovetail Saddle for Planewave 7.652" dovetailon AP 1200, 1600 and 3600

SBPW2323" P-Style Dovetail Plate for DOVEPW

DOVE3622
SB3622SB3627

22" Dovetail Saddle for 3600
Dovetail Plate for DOVE3622 Saddle(6) 3/8-16 x 1" SHCS
(6) 1/4-20 x 1" SHCS
(2) 3/8-16 x 1/2" low profile SHCS
(4) 1/4-20 x 5/8" SHCS
(6) 3/8-16 x 1" SHCS
(4) 3/8-16 x 1-1/2" SHCS
(2) 3/8-16 x 1/2" low profile SHCS
(4) 1/4-20 x 7/8" SHCS for lock-down
1/6/202052