ASTRO-PHYSICS 1600GTO User manual

1600GTO German Equatorial Mount with
GTOCP4 Servo Motor Drive
Mounts Shipped
Starting in
November 2016
Astro-Physics, Inc.
11250 Forest Hills Road
Machesney Park, IL 61115
Telephone: [phone]
Fax: [phone]
[email protected]
www.astro-physics.com
August, 2018
Keypad Optional

1
ASTRO-PHYSICS
1600GTO GERMAN EQUATORIAL WITH
GTOCP4 SERVO MOTOR DRIVE
ABOUT THIS MANUAL 3
1600GTO PARTS LIST 4
MECHANICAL SPECIFICATIONS 5
INTRODUCTION 6
Why Polar Alignment is Important 6
ASSEMBLY DIAGRAM 7
PLAN AHEAD AT HOME 8
Handy Tools to Have on Hand 8
Quick Start Summary – New Installations 8
AT YOUR OBSERVING SITE 9
Assemble Pier (purchased separately) 9
Attach Polar Axis Assembly to Pier 9
Latitude Adjustment for 1600GTO German Equatorial Mounts 10
Special 90 Degree Alt-Azimuth Position 11
ASSEMBLY INSTRUCTIONS 12
Assembly of R.A. and Dec. Axes 12
Assembly Procedure: 12
Disassembly procedure: 13
CABLE MANAGEMENT 14
Preparation 14
The Basics 14
The Specics 14
Routing Cables if You Plan to Use the Cable Router Insert When Using the Polar Scope 15
Routing Cables if You Don’t Plan to Use the Cable Router Insert 16
ATTACH MOUNTING PLATE 17
Fixed Mounting Plate Options 17
Losmandy D-Style Compatible Saddle Plates 18
Astro-Physics Dovetail Option 18
Side-by-Side and Vixen Style Plate Options 19
Astro-Physics P-Style Compatible Saddle Plates 19
ATTACH COUNTERWEIGHT SHAFT AND COUNTERWEIGHTS 20
ATTACH MOUNTING RINGS AND SCOPE 20
UNDERSTANDING THE R.A. AND DEC. CLUTCH KNOBS 21
BALANCING THE TELESCOPE 22
Preliminary Balancing 22
Precision Balancing 22
Disengaging the Worm and Worm Wheel 22

2
ALTITUDE AND AZIMUTH ADJUSTMENTS – ROUGH POLAR ALIGNMENT 24
POLAR ALIGNMENT OPTIONS – FINE POLAR ALIGNMENT 25
Methods for ne polar alignment 25
Making Precise Altitude and Azimuth Adjustments 26
Fine Altitude Adjustment 26
Tips for Adjusting the Altitude 26
Fine Azimuth Adjustment 27
Precision-Adjust Rotating Pier Base with Azimuth Bearing 27
Using Software to Improve Pointing Accuracy 27
MISCELLANEOUS ITEMS 28
Bubble Level and Lanyard Post 28
Reference Orientation Lines 28
Warning for Dec. Servo Cable 28
SLEWING YOUR MOUNT IN BELOW FREEZING TEMPERATURES 29
AUTO-ADJUSTING GEARBOX - NO MORE WORM MESHING! 30
Checking and Adjusting the Gearbox Backstops in R.A. and Dec. 30
What to do if you believe that there is a backlash in the gearbox 31
SOME IMPORTANT NOTES 32
MOUNT CARE, CLEANING AND MAINTENANCE 33
Care 33
Cleaning and Touch-up 33
Routine Mount Maintenance 33
Worm Wheel Maintenance 33
TROUBLESHOOTING, TIPS AND SUPPORT 34
Troubleshooting and Tips 34
Additional Support 37
APPENDIX A: 1600GTO ABSOLUTE ENCODERS 38
Part numbers and description 38
What’s Included in the Kit 38
Absolute Encoder Cable Connections 38
APAE Utility 39
APPENDIX B: DECLINATION AXIS BACKLASH TESTS 40
PulseGuide™ 40
Dec Backlash Test 1 40
Dec Backlash Test 2 40
After Running Tests 1 and 2 41
Dec Backlash Test 3 41
MaxImDL™ 41
Step 1 41
Step 2 41
Step 3 41
APPENDIX C: MOUNTING PLATE FASTENER CHART 42

3
ABOUT THIS MANUAL
This version of the 1600GTO Manual was prepared for the production run of mounts that began shipping in November of
2016. Most of the information in this manual is applicable to all 1600GTO mounts that have been produced.
You should also note that this manual is actually one component of a three document system. In the past, we had two
manuals for each mount - one for the individual mount and another manual for the keypad that applied to all mounts.
Starting in the summer of 2011, we further divided the mount manuals to allow us to present the GTO Servo Motor Drive
System in greater detail. Like the Keypad Manual, the GTO Manual is universal to all mounts that use the Astro-Physics
GTO Servo Motor Drive System with the GTOCP4 Servo Control Box. This 1600GTO Manual, on the other hand, will
cover the 1600GTO’s mechanical features and physical operations.
Note: Some photos may differ slightly from the current mounts that are shipping.
As always, we highly recommend the Technical Support Section of our Web site for the latest information and for future
updated versions of this manual.
A nal note and an apology to our friends in the southern hemisphere. Many of the instructions in this manual are written
entirely from the point of view of those of us in the northern hemisphere. Since descriptive terms like left and right are
meaningless without a dened point of reference, we tend to use east and west to avoid ambiguity. The east and west
sides of a German equatorial mount are, of course, reversed in the southern hemisphere. At one point, our thought was to
always use phrases like the following: “... on the east side (west side in the southern hemisphere) ...” This quickly became
cumbersome and made the text more difcult to read. For simplicity, we decided to leave many of the explanations in
their northern hemisphere framework. To our southern hemisphere friends: We love you no less and apologize for this
unintended slight. We know, however, that you are all smart enough to make the necessary translation to “down under”
appropriate instructions. Thank you for your understanding.
Please RecoRd the Following inFoRmation FoR FutuRe ReFeRence
Mount Serial Number: _____________________________________________
GTOCP4 Serial Number: _____________________________________________
Keypad Serial Number: _____________________________________________
Purchase Date: _____________________________________________

4
1600GTO PARTS LIST
1 Polar Fork / Right Ascension Axis (R.A.) Assembly
1 Declination Axis (Dec.) Assembly
1 Dec. Top Plate (S1600DTP)
1 GTO Servo Control Box (GTOCP4)
1 22” x 1.875" Stainless Counterweight Shaft (M12601-E) with machined Safety Stop (M12676)
1 R.A. Cable Router Insert (M16145-A)
1 Mount to GTOCP4 Cable (CABGTOR19)
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
10 3/4” x 8” Velcro Cable tie wraps
1 CD containing: PEMPro™ v3 Software (written by Ray Gralak of Sirius Imaging) and PDFs of manuals
Instruction Manuals and Registration Card
Fasteners:
(6) 1/4-20 x 3/4” SHCS (for safety backup of dovetails)
(7) 5/16-18 x 5/8” SBHCS (pier adapter) (6 + 1 extra)
(7) 5/16” at washers (pier adapter)
In 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.
● 10” O.D. pier: Astro-Physics has several heights and styles to choose from.
● Counterweights: 5 lb. (5SCWT), 10 lb. (10SCWT), 18 lb. (18SCWT) and 30 lb. (30SCWT188) are available.
● Regulated Power Supply (110V AC to 12V DC converter): We recommend the Variable-volt, 25-amp supply
(PSVPW25A) 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 Specications on next page. We recommend having separate batteries – one for
the 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 Inline Watt Meter and Power Analyzer (CABPPWM) - To monitor your power consumption.
Several additional options are available:
● Optional GTO Keypad controller with 15’ coiled cable. Hand-held computer to operate the mount without a PC and
additional software.
●9” Counterweight Shaft Extension (M12675): For heavier loads.
●Autoguiding accessories: Various guiding congurations can take advantage of the 1600GTO’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 (TRAY10) and/or Eyepiece Accessory Trays (TRAY10H)
with Bi-Level (TRAYSB) or Single Level (TRAYSB1) Support Bars. Keep things close at hand.
●1600 Flat Surface Adapter (1612FSA): For attaching the 1600GTO to your own custom pier or tripod.
●1600 Flat Surface Adapter with Flat Pier Plate (1612FSA-FP): For attaching the 1600GTO to the Advanced
Telescope System (ATS) pier, or to your own custom pier or tripod when a at pier plate is needed.
●Polar Alignment Scopes: AP Right-Angle Polar Alignment Scope (RAPAS) and Losmandy Polar Alignment Scope
(PASILL4-179) – Many users nd a polar alignment scope useful for zeroing in on the pole quickly, particularly with
telescopes that are not orthogonal to the mount.
For a complete listing of our 1600GTO accessories, visit our Web site – www.astro-physics.com.

5
MECHANICAL SPECIFICATIONS
Construction All CNC machined aluminum bar stock, stainless steel, brass; stainless steel fasteners
Finishing and Assembly Every part is hand-nished and inspected. All assembly is done by hand, by highly skilled
mount assembly staff.
Worm wheel - R.A. & DEC. 10.3” (262 mm), 225 tooth aluminum
Worm gear - R.A. & Dec. 1.22” (31 mm) diameter, special low-wear alloy
Axis shaft - R.A. & Dec. 3.74” (95 mm) diameter
Shaft axis bearings - R.A.
& Dec. 5.71” (145 mm) diameter
Latitude range 0 to 78 degrees and 90 degrees for Alt-Az
Azimuth adjustment Approximately 13 degrees (± 6.5 degrees from center)
Counterweight shaft 1.875” (47.6 mm) diameter x 22” (559 mm) long, includes large machined safety stop knob;
weight: 17.2 lb. (7.8 kg). Optional 9” (229 mm) shaft extension available.
Weight of mount
R.A. axis / polar fork: 63.7 lb. (28.9 kg)
Dec. axis: 40.0 lb. (18.1 kg)
Dec. top plate 3.0 lb. (1.4 kg)
Capacity of mount
Approximately 220 lb. (100 kg) scope and accessories (not including counterweights),
depending on length. Recommended for refractors up to 250 mm, 18-20” 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 base 9.775” (248.3 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 specications, please see the
GTO Servo Drive System Manual.

6
INTRODUCTION
The 1600 German equatorial was designed to meet the needs of the advanced observer who requires a mount with
maximum strength and rigidity and minimum weight. The excess material in both axes has been carved out while retaining
a 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 eld 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, PulseGuide™ 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, this mount 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 be
very 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, the
servo controller was designed to work with any software that was written to use our published command set. We do not
lock you into any proprietary software or mandatory “additional” equipment. To increase the versatility of all our mounts,
we have developed and now fully support a V2 ASCOM Driver for use with all ASCOM client software.
As mentioned above, we also include PulseGuide™ mount control / utility software and 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 1600GTO mounts will come pre-loaded with the custom-tted PEMPro™ corrections from our
extensive individual testing that is performed on each and every mount. While the native periodic error of your 1600GTO
will be 5 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 1600GTO’s control and performance options will be greatly enhanced by
the Astro-Physics Command Center (APCC). APCC fully addresses all the capabilities of the 1600GTO, and adds
enhancements not currently available in the keypad or in any other software.
The 1600 is equally at home in a permanent observatory or as a portable mounting for remote star parties thanks to the
ease with which the two axes come apart. This is the perfect
mount for a large refractor, Newtonian, Cassegrain or
astrograph.
In order to maximize your pleasure on your rst night out, we
recommend that you familiarize yourself with the assembly
and basic operation of the mount indoors. The temperature
will be comfortable, the mosquitoes at bay, and you’ll have
enough 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.
Why Polar Alignment is Important
Polar alignment permits accurate R.A. movement in order to
compensate for the Earth’s rotation.
If you were to take a long exposure photograph with Polaris
(often called the north star) in the center of the eld, 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 to
compensate for the earth’s rotation by moving the telescope
at the same rate and opposite to the earth’s rotation. When
the polar axis of the telescope is pointed at the celestial pole
(polar aligned) as shown in the diagram at right, the mount
will follow (track) the motions of the sun, moon, planets and
stars. As a result, the object that you are observing will
appear motionless as you observe through the eyepiece or
take astrophotos.
Equator
South North
Direction of
the Celestial
North Pole
Earth
Direction of
the Celestial
North Pole
Direction of
the Polar Axis
Horizon
Zenith
Earth’s Axis
L
a
t
i
t
u
d
e
L
a
t
i
t
u
d
e
Northern
Hemisphere
Earth’s Rotation
Mount’s
Counter-rotation

7
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 1600GTO mount. The model 1600GTO 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 particular
attention 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. Servo Cable internally.
Declination
Motor/Gearbox
R.A. Motor/
Gearbox
Counterweight
Shaft
GTOCP4
Control
Box
Azimuth Adjuster
Polar Axis
Pivot Bolt
Altitude
Adjuster Knob
Polar Axis
Lock Knobs (4)
Dec. Sight Hole
Cover
Clutch Knobs
(3 each axis)
Dec. Top Plate
Lock Knobs (2)
Cable
Channel (2)
Encoder
Connector
GTOCP4
Cable
Cable Access
Cover
Dec. Lock
Knobs (2)
Declination
Counterweight
Adapter Encoder
Cover
Plates
R.A. Sight
Hole Cover
R.A. / Dec.
Cable Covers
Declination
Axis Housing
Safety Stop
R.A. Axis
Housing
Polar Fork
Assembly
Dec. Top Plate
Safety
Screw (4)
Safety
Screw (2)
Dec. Cable
Covers

8
PLAN AHEAD AT HOME
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 with
you 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 longitude and latitude of your current site will display. Apps are available for
iOS, Android and Windows.
Quick Start Summary – New Installations
This summary gives an outline of the workow to have a successful rst 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 even
take delivery of your mount.
a) Set up ASCOM and the drivers rst
i) ASCOM Platform 6.3 (currently) - ascom-standards.org
ii) AP V2 ASCOM driver - http://www.gralak.com/apdriver
iii) 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_nd4.pdf
b) Install third party software (Starry Night, TheSkyX, MaxImDL, etc.)
c) Adjust software settings - follow the appropriate Workow documentation that follows in this guide
d) If using the Keypad along with a computer, set the Keypad to AutoConnect=EXT and power cycle the mount in
order to lock in the change.
2. Assemble the mount.
3. Balance the system.
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-dened 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 rst.
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 nishing your night’s observing (or day’s solar observing) it is best to park the mount into your chosen Park posi-
tion 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.

9
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 (or
toward the south if in the southern hemisphere).
2. Place the pier post on the base, orienting the eyelets for at-
taching 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 your
weight 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 a
graphical representation. At this stage of the assembly process, you want to position the pier so that it points roughly
north.
1. Prior to mounting the Polar Axis. Adjust the Azimuth Ad-
juster so that the Azimuth Adjuster Block is centered. This will
allow adjustability when it comes time to polar align the mount.
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 to the north so that the
offset weight of the counterweight shaft and counterweights do
not create an unstable balance.
3. Set the R.A. Axis in place. Carefully set the 1600GTO Right Ascension Axis / Polar Fork assembly into the open top
of your pier, or into the 1600 Flat Surface Adapter (1612FSA), if you are using one. Unless you are quite strong, it is
ideal to have two people involved in the operation of lifting and stabilizing the assembly as it is positioned into the pier
or 1612FSA.
4. Line up the Pier base. If the side thru-holes in the pier or 1612FSA are not perfectly lined up with the tapped holes
in the mount’s Pier Adapter base, rotate the mount, noting that the azimuth adjuster knobs should be locked to the
adjuster block. Otherwise, the base will rotate making it difcult 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 at 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 the
pier so that no marring of the nish 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 nally 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
the adjustment. 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 an adjustment to both directions 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 to achieve accurate polar
alignment. Level the mount...you’ll be ahead in the game!
Special note: It is a very good idea to include a small torpedo level and a compass in your accessory carry box,
along with your other tools, when setting up portably. Modern cell phones, such as the iPhone, have Apps
available that allow the phone to be used as a level, an inclinometer and a compass.
Azimuth Adjuster
(underside view)
Azimuth Adjuster Block
Azimuth Threaded Push Rod

10
Latitude Adjustment for 1600GTO German Equatorial Mounts
The 1600 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 more
compact, 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
1. Use only the R.A. axis. DO NOT attempt to make these adjustments with the declination axis in place and certainly not
with an instrument fully mounted.
2. Loosen all four Altitude Lock Knobs about 1 turn.
3. The mount’s Polar Axis is held in place between the two side plates of the Polar Fork. The axis pivots on custom
shoulder bolts located towards the rear of each side plate. These bolts should not be loosened when making altitude
changes to the mount.
4. Tilt the R.A. axis upwards and hand tighten the lock knobs so that the axis does not drop while you are repositioning
the Altitude Adjuster Bar.
5. Note that the Altitude Adjuster Knob is attached to a threaded rod that travels through the Altitude Adjuster Bar. Turn
the knob so that you see about half of the threaded rod protruding from both sides of the Altitude Adjuster Bar. This will
allow you to move 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°
c) Slot 3 - 19-29° center: 24°
d) Slot 4 - 28-38° center: 33°
e) Slot 5 - 37-47° center: 42°
f) 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 the 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.
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 back of the worm wheel housing to assist you. (See photo following page)
Socket
Insert
Rod
Altitude Knob
Altitude
Slots
DO NOT Loosen
Pivot Bolt
Polar Axis
Lock Knobs
Altitude
Adjuster
Bar
Altitude
Adjuster
Position
Slots (9)
Polar Axis
Lock Knobs
Azimuth
Adjuster

11
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 Altitude Lock Knobs and lower the polar axis be sure that the rod
comes to rest fully seated in this 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 the previously mentioned al-
titude lines on the side). Tighten the altitude locking knobs with nger
pressure only. You do not need to tighten with the hex key.
9. Later, as you adjust the mount’s altitude when polar aligning, you
should always make the nal adjustments pushing upwards. Addition-
ally, the locking knobs should be increasingly tightened as the nal
adjustments are made.
Recommendation: Rough polar positioning of the mount and 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 weight and 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 ne adjustments. An inclinometer and a compass adjusted for magnetic declination at your loca-
tion (or these functions on a smart phone App) are recommended.
Special 90 Degree Alt-Azimuth Position
One of the unique design features of the 1600GTO 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 reversed
in 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 the
Dec. axis so that you are only working with the R.A. axis and forks.
2. Remove all four Altitude 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 per-
son remove the two shoulder
bolts that are the Pivot Bolts for
the axis. Remember that the
full weight of the axis will need
to be supported.
5. Lift the axis straight up and out
of the polar forks. Walk around
to the other side of the mount
so that the R.A. axis can then
be lowered back into place, but
now facing the other way.
6. Align the Pivot Bolts with their respective threaded holes and screw into place. Do not tighten them until both bolts
have been fully threaded and the axis rotated slightly back and forth to ensure that it is properly seated. Now tighten
the bolts fully.
7. Replace the four Altitude 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 the
knobs tightly using a 1/4” hex key. You now have an Alt-Azimuth mount.
Important Note: We do not offer software for the 1600GTO mount congured 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.
(Not Used)
Indicator Line

12
Declination
Axis Locking
Knob (2)
A
B
OFF
ON
ASSEMBLY INSTRUCTIONS
Assembly of R.A. and Dec. Axes
One of the many features of the 1600GTO mount is internal
wiring. Internal wiring adds protection and convenience. It
eliminates many of the concerns, such as cable-snags and
excess dew exposure to electrical parts, when the telescope is
in use both in the backyard and at remote sites.
Much of the wiring is factory installed and not of concern to the
user. However, the exception is the Dec. servo connection. It
is necessary to attach the Dec. Servo Cable to its connector
when joining the Dec. and R.A. axes. It is equally important
to remember to detach the connection when separating the
mounts two axes. Otherwise, damage could occur to the
internal socket / circuit board or the Dec. axis could be pulled
from your hands as you start to walk away.
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.
1. Ensure that the R.A. (polar) axis is securely attached to its pier before proceeding.
2. You will notice that the Dec. Servo Cable routes through the R.A. axis. There is also a
removable Cable Router Insert (seen at right) provided with the mount which serves the
purpose of keeping any internal cables out of the light path of the polar scope. If you
will not be using a polar scope, then you have the option of not using the cable router.
Position the Dec. Servo Cable along the side of the insert and loop it back into the center
of the insert. This will keep the cable out of the way when attaching the Dec. axis to the
R.A. axis.
3. Rotate the R.A. axis to the position shown in the illustration with the two clutches at the top and the single clutch at the
bottom. Note that the auxiliary cable channels line up vertically and that the Dec. locking knob dovetail insets are at the
bottom.
4. 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 (the knob is removed with
approximately 21 turns).
5. Position the Dec. axis above the R.A. axis (as illustrated with
the image to the 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 seat them (shown by arrow “A”).
6. When the Dec. axis is fully seated, hand tighten the two locking
knobs fully.
7. There are four 1/4” counter-bored holes (two on each side) on
the front of the Dec. axis. Insert a 1/4-20 x 3/4” socket head cap
screw into each of the holes and tighten. It is important that you
tighten the locking knobs fully before adding these screws,
so that the dovetail of the Dec. axis is properly seated. These
provide additional security and rigidity for the heavier capacity of
the mount.
8. 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.
9. Reach inside the axis and retrieve the Dec. Servo Cable that
Clutch (3)
Clutch Knob (3)
Dec. Lock Knob
Dovetail Insets
Aux Cable
Channel (2)
Altitude
Adjuster Knob
Dec. Servo
Cable
Cable Router
Insert
Lockdown Hole
for Dec. Axis (2)
(design variations
may include 4-8 holes)
Polar Scope
Sighting
Channel
Cable
Channel
CP4
Control
Box
R.A. (Polar) Axis Hub
Cable Router

13
was inserted into the center of the R.A. axis Cable Router. Connect
the cable to the connector box as shown in the illustration and tighten
the retaining ring.
10. Replace the Dec. Counterweight Adapter.
11. Thread the counterweight shaft into the Dec. axis. Ensure that the
plastic washer is in place on the threads of the shaft so that the shaft
will be easier to remove later.
12. Attach the Dec. Top Plate to the axis 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 attach-
ment 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.
Disassembly procedure:
1. Essentially, one reverses the assembly procedure. Start by removing the telescope, counterweights and counterweight
shaft.
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. Reach inside the axis and disconnect the Dec. Servo Cable at the
connector box as shown in the illustration (see above illustration).
Tuck it back into the center of the R.A. axis for safety and to prevent
damage.
DO NOT FORGET to disconnect this cable before separating
the axes!!!
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 previous illustra-
tion.
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.
Cwt Shaft
Adapter Leverage
Hole (2)
Dec. Servo
Cable
Dec. Counterweight Adapter Removed
Encoder
Connector
Cable
Clips

14
CABLE MANAGEMENT
It has become more important than ever to nd ways to manage cable routing. We now have the lure of imaging and with
it the addition of accessories requiring power and computer connectivity. Apart from multiple dew heater cables, we now
have CCD cameras, color lter wheels, camera rotators, motorized focusers, autoguiders, adaptive optics units and the
list 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 exure that results in bad star shapes in your images; at worst, they
cause cable snags and damage to your equipment.
We have gone to great lengths in designing and engineering the 1600GTO mount to accommodate advanced cable
management. This job was made more complicated by our philosophy that our mounts should be portable and the two
axes need to be able to be separated for the ease of setup and transport by our customers. Since our mounts can be
portable, we further added to our challenge by requiring the ability to use a polar alignment scope for speeding set up time
and alignment accuracy. We have succeeded. The 1600GTO allows you to pass all your cables through the mount while
maintaining a visual 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°) while
cables are inside. You can damage the cables. Operations where this might occur are balancing, re-
greasing and other maintenance activities. GTOCP4 software versions VCP4-P01-11 and later will not
allow 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
wish to take it. 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 when it becomes necessary to remove a large and heavy systems in order to do so.
It is best to lay out your imaging system and connect all the wiring so that you have a good idea of which cables need to
be routed 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 mount
to 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 1600GTO 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. It is also removable via a unique and
powerful dovetail system so that you have unobstructed access to 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 Insert which is removable. This insert serves the dual purpose of organizing
the routing of cables while preserving a clear light path for the polar scope. In a permanent observatory setup, it is not
necessary to use the insert, though it may certainly 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 nal part of the internal cable routing system is the Cable Access at the bottom of the rear R.A. Plate. This access has
a cover that is removable by undoing the two socket head cap screws securing it. Once removed, cables with connectors
as large as RS-232 cables can be fed through the opening. It is always a good idea to feed the largest connectors through
rst before moving on to the smaller sizes. If you do not plan to use a polar scope, you have the additional option of
routing the cables through the central opening.
The Specics
What follows are some more detailed instructions for installing your cable package into the 1600GTO. You will, of course,
have to tailor the instructions for your own particular needs. These instructions are for the routing of auxiliary cables for

15
cameras, dew heaters, focusers and other devices that are not a component of the 1600GTO. The mount’s own cables
are 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 1600GTO. 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 insert and can
run your cables through the mount while the two axes are joined. This has the advantage of more easily adding a cable
later by shing 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 rst.
We shall rst 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 insert. It is only possible to run
cables with small connectors after the cable router is in place and it may present difculties once the mount has been fully
assembled and equipment in place. As one sees in the illustration of the R.A. Axis Hub, the Cable Router creates three
narrow cable paths around the outside of the light path. However, the Cable Router Insert is easily removed and replaced
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 Insert When Using the Polar Scope
1. Start with the R.A. (polar) axis properly installed on your pier.
2. Remove the Cable Router Insert and set 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 used while
cables are routed through the mount.
Note: you may nd it helpful to also remove the Polar Scope Adapter Cap in order to 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 nesse the cable through the rear Cable Access opening. If you
are having trouble coaxing the connector through the opening, you can always use the electrician's trick of rst snak-
ing a length of cord or thick string through the cable channel by attaching it to the end of a straight wire or similar probe
of sufcient length to pass through the axis. Continue feeding your cables through the cable channel. Note that if you
have a number of cables to run, then it may be best to use the electricians trick and pull them all through at one time.
5. Insert the Cable Router into place while making sure that the installed
cables are positioned in the channels. If you have a number of 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 de-
scribed 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.
7. Attach the Dec. axis as described earlier and lock into place with the
Lock Knobs. You will also want to place and tighten the two socket head
screws that provide attachment security. Remove the Dec. Counterweight Adapter.
8. At this point you will unloop and route the Dec. power / communications cable
as described in the R.A. / Dec. Assembly section. Attach it to its Dec. socket.
Replace the Dec. Counterweight Adapter.
9. Next unloop and route the remaining cables up through the center of the Dec.
axis. Cable lengths can be adjusted at this point.
Note: It may be advisable to make a tool for snagging the wires and pulling them
up through the Dec. axis. This can be done by bending a wire clothes hanger (or
similar) into a hook shape. Be sure to take care not to damage any of the interior
wiring in the mount.
Cable Access
Polar Scope Cap
R.A. Rear Cover Plate
Cable Router Insert
Cable
Channels
Light
Path
R.A. Axis Center
Cable Router
Installation

16
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 to the axis 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 3/4” 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 Insert
1. Start with the R.A (polar) axis properly installed on your pier.
2. Remove the Cable Router Insert, if it was installed.
3. Attach the Dec. axis as described earlier and lock into place with the Lock Knobs. You will also want to place and
tighten the two socket head screws that provide attachment security. Remove the Dec. Counterweight Adapter and
connect the Dec. power / communications cable as previously described.
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 be
done by bending a wire clothes hanger (or similar) into a hook shape. Be sure to take care not to damage any of the
interior wiring in the mount.
5. Begin by rst 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 nesse the cable through the opening and up through the center of the axis. If you are hav-
ing trouble coaxing the connector through the axis, you can always use the electrician’s trick of rst snaking a length of
cord or thick string through the cable channel by attaching it to the end of a straight wire or similar probe of sufcient
length to pass through the axis. Continue feeding your cables through the cable channel. Note that if you have a
number of cables to run, then it may be best to use the electrician’s trick and pull them all through at one time.
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.
Note: This may be a good time to recommend routing a cord or thick string through the mount while routing the cables. It is
convenient to have this option available to you should you ever wish to add a cable for a new device at a later date. It can
simply be left in place until needed.
7. 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.
8. Attach the Dec. Top Plate to the axis 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 3/4” 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 prop-
erly seated.
Dec. Top Plate Removed Dec. Top Plate in Place

17
ATTACH MOUNTING PLATE
(purchased separately)
Take note of the hole-patterns available on the Declination Cap
of the 1600GTO. Most of you will use either the outer six-hole
bolt pattern or else the inner four-hole bolt pattern to attach
your mounting plate. Some of the plates can use bolt holes
from both the four and six hole-patterns. Please note that the
mounting plates below are drawn at a smaller scale than the
hub at right. The plates are relatively at scale with each other
for comparison.
Several mounting plates (also called cradle or saddle plates)
are available for the 1600 mount. If you own more than one
instrument, you may need more than one plate. Follow the
appropriate directions for the plate(s) that you have. The
darkened holes represent those used for the 1600 mount.
Fixed Mounting Plate Options
18” Flat Mounting Plate (FP1800)
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 pairs of keyhole slots that measure 3.2” between
centers are provided. The two inner pairs are 13.75”
apart and the outer two pairs are 17” apart. You can drill
additional holes to suit your needs. This plate also ts
the 900, 1100 and 1200 mounts. Attach this plate with six
1/4-20 x 1” at head socket cap screws.
15” Ribbed Mounting Plate (1200RP15)
This plate is 14.75” long, 7.75” at its widest point, 5” at each end and
1” thick. The underside of the plate is carved into a ribbed pattern
to maximize the strength and minimize the weight - 3 lb. A pair of
keyhole slots that measure 3.2” between centers are provided at each
end. The distance between the pairs is 13.75”.
Attach this plate with six 1/4-20 x 3/4“ socket head 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.
24” Ribbed Mounting Plate (1200RP)
For larger instruments, the ribbed structure of this plate provides the maximum support. Our machinist begins with thick
aluminum plate and carves a strong rib structure. The nal result is 1.5” thick, 24” long and 7.6” at its widest point. The
width of the plate tapers to 5.5” at each end. A
pair of keyhole slots that measure 3.2” between
centers are provided at each end. The distance
between these pairs of holes is 23”. Due to the
ribbed structure, you may not be able to drill
additional holes for non-Astro-Physics mounting
rings. The plate weighs an amazing 9.5 lb. for
its size. This is a view of the rib structure on
the underside of the 24” plate.
Attach this plate with six 1/4-20 x 1” socket
head cap screws.
1600GTO Dec. Top Plate Mounting Hole Pattern
Six 1/4-20 tapped holes
spaced @ 60° intervals
Bolt circle - 6.875”
Four 1/4-20 tapped holes
@ 45°, 135°, 225° & 315°
Bolt Circle - 3.200”
Two 1/4-20 tapped
holes @ 0º & 180º
Bolt Circle 4.000”
Optical
Axis 0°
Outside diameter
7.475”

18
Losmandy D-Style Compatible Saddle Plates
16” Easy-Balance Dovetail Saddle Plate for Mach1GTO, 900, 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 the
center clamp for even greater versatility. The
DOVELM162 provides a multitude of mount
attachment options, and was specically
designed to meet the balancing demands of
“back-end-heavy” instruments like SCTs and
Ritchey-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
SBD16 16” Versatile Dovetail Plate!
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” at head socket cap screws.
Astro-Physics Dovetail Option
15” Astro-Physics Dovetail Saddle Plate (DOVE15) for 15” Sliding Bar (SB1500)
The 15” version of our dovetail plate is suited for the 130 StarFire scopes, ARO Maksutovs, Takahashi scopes and other
instruments of similar size. The knob assembly features a
brass pin with a tapered end to hold your sliding bar rmly
without marring the aluminum. Use with the 15” Sliding
Bar (SB1500), which is sold separately (NOT for use with
Losmandy “D” or “V” plates or Vixen plates). Also makes
a great accessory plate when used with any conguration
employing the standard AP 13.75” ring spacing, including
the SBD16, 1200RP15 or FP1800 (with rings mounted to
inside holes).
Attach with four 1/4-20 x 5/8 at head socket cap screws.

19
Side-by-Side and Vixen Style Plate Options
13” and 16” Side-by-Side D Series Plates (SBD13SS & SBD16SS)
These plates will t into any of the three D-series compatible plates listed
above and will accept either the DOVELM2 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” (318 mm) optical centers.
12” Vixen Dovetail Converter (SBD2V)
This 12” plate lls the void for those customers whose telescopes use the
Vixen-style mounting plate including the Losmandy V-Series. Now there is no need to replace your existing Vixen-style
bar, rings, or clamshell to accommodate your Astro-Physics mount.
The top portion is a female plate that accepts Vixen-style bars. In order to retain the tilt-in feature of the dovetail, the
sliding bars must have an approximate width (at the widest point) between 1.65” (42 mm) and 1.8” (45 mm) and they must
have have a 75 degree bevel on each side. The bottom portion is a standard D-series dovetail that will t into any of our
D-Series compatible saddle plates.
Please note that we are not great fans of the Vixen style design.
It is our belief that the 75 degree bevel does not provide an
adequate safety margin for the clamps. We have not tested all
plates that are currently available on the market. We recommend
you check your plate for a good t in this saddle without an
instrument attached! Also, note that the top portion of this plate is
NOT designed to be used with our SB0800, SB1000 or SB1500
sliding bars.
Astro-Physics P-Style Compatible Saddle Plates
16.5” Dovetail Saddle Plate for PlaneWave Dovetail Plates (DOVEPW)
This robust plate allows attachment of instruments like the PlaneWave CDK17
or CDK20 that use their 7.652” wide dovetail plate. The plate was originally
designed for the 3600GTO mount, but it works extremely well on the 1600GTO
with the PlaneWave CDK17 and CDK20. We do not recommend their larger
scopes for the 1600GTO. Four clamps secure the instrument like a vise! Note
that the attachment screw placement requires that the plate be rotated 90
degrees from the conventional orientation in order to accommodate the two
center clamps. You can achieve an added measure of security when using
our 23” P-Style Dovetail Plate (SBPW23). A series of matching 1/4-20 holes in
each plate enable you to bolt them together once the balance position of your
instruments is achieved. Attach with six 1/4-20 x 1” socket head cap screws.
Side-by-Side Congurations with P-Style Saddles
A variety of P-style side-by-side congurations are possible
using the 23” Dovetail Plate (SBPW23). One example is
shown in the photo to the right where a P-style Dovetail Saddle
(DOVEPW) is attached on the right and a 16” Losmandy
D-style Dovetail Saddle (DOVELM162) is attached on the
left. It is also possible to set up a side-by-side conguration
using two, or even three, DOVELM162 saddles attached to the
SBPW23. When assembling a multi-scope system you have to
be mindful of the total combined weight of the components and
accessories (remember that a simpler system is always better).
An additional DOVEPW will be used to attach the SBPW23 to
the mount.