The PlaneWave Instruments CDK20 is a 20 inch (0.51 m) f/6.8 Corrected Dall-Kirkham Astrograph telescope. The CDK20 has a dual carbon-fiber truss design, with 3 cooling fans ejecting air from the back of the telescope. The CDK20 covers a 52 mm field of view without any field curvature, off-axis coma, or astigmatism. The instrument weight is 140 lbs (64 kg) and comes standard with a back plate retaining ring ready to accept the focuser of your choice.
All CDK20 telescopes come with fused silica primary and secondary mirrors.
The L-Series combines versatility, simplicity and affordability by combining all the technology of our Observatory class telescopes into a compact stand-alone mount. In its Alt/Az configuration it is considerably more compact than its equatorial counterpart, allowing a larger telescope to fit in a smaller enclosure. The mass it takes to make a rigid alt/az mount is substantially less, leading to cost savings. Unlike German Equatorial mounts, there are no meridian flips to deal with, and no large protruding counterweights to create a dangerous hazard in a public observatory. Alt/Az is more intuitive to use and no polar alignment is needed. Besides, it is the way the pros do it!
L-Series Mount Features:
- Direct-drive motors on each axis for smooth, fast, and virtually silent movement of the telescope
- Slew speeds up to 50 degrees per second
- High resolution encoders on each axis for precise positioning
- Zero backlash
- Zero periodic error
- PointXP mount modeling software
- Enclosed electronics
- Through the mount cabling
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Direct drive motors and encoders
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Direct Drive motors and on-axis encoders eliminate the need for gears, thereby eliminating backlash and periodic error. With high-resolution encoders providing the feedback for the direct drive motors, not only will the telescope track without periodic error and backlash, the mount will also counter wind gusts with precise servo feedback.
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Incredible Slew Speed
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The direct drive motors can move the telescope at speeds up to 50 degrees per second for tracking satellites or just to minimize target acquisition time. |
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Dual mounting bracket
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PlaneWave style mounting bracket to hold CDK17/20 onto inside of fork arm with additional option of mounting a scope on the outside of the fork arm. Optional dovetail clamp required. |
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Azimuth dovetail balance system
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For precise center of gravity balance whether in Alt-Az or Equatorial configuration |
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Through the mount cabling
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Access panels in the fork arm and azimuth axis allow for camera equipment cabling through the inside of the mount. |
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Proven CDK700/PW1000 Technology
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The L-Series uses the same proven technology as the CDK700 and 1-Meter PW1000 which are being used in Universities round the world. |
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Technical Specifications
Mount System
| Type |
Alt-Azimuth / Equatorial Direct Drive Mount |
| Weight |
257 lbs (100 kg) |
| Component Weights |
Azimuth Base – 121 lbs, Fork Arm – 136 lbs |
| Max. Load Capacity |
200 lbs (91 kg) |
| Latitude Range |
0 to 90 degrees, Northern and Southern hemispheres |
| Cable Management |
Equipment cables can be wired through mount |
Control System
| Control Electronics |
PlaneWave Interface dual axis telescope control |
| User Interface |
PlaneWave Interface 4 (PWI4) Control Software with integrated PointXP mount modeling software |
| Homing Sensors |
Home position sensors are included allowing the mount can find its home position on power up. |
| Slew Rate |
20 degrees per second (standard); 50 degrees per second (maximum), both axes |
| Power Requirement |
Accepts 120 VAC. Supplied with 12VDC 15A Regulated Power Adapter |
Optical System
| Aperture |
20 inch (508 mm) |
| Focal Length |
3454 mm (135.98 inch) or 3947 mm (155.4 in.) |
| Focal ratio |
F/6.8 or f/7.77 |
| Central Obstruction |
39% of the Primary Mirror Diameter |
| Back Focus from Mounting Surface |
f/6.8-8.81 in. (223 mm)
f/7.77-10.6 in. (269.24 mm)
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| Weight |
140 lbs (63.5 kg) |
Motion Control
| Motor Control |
Industrial grade brushless motor control system and built in electronics |
| Motor – Azimuth and Altitude |
Direct Drive 3 Phase Axial-Flux Torque Motors |
| Encoder – Azimuth and Altitude |
152mm stainless steel encoder ring with reader built into the azimuth and altitude axes. 18,880,000 counts per revolution (0.069 arcsecond resolution). |
| Motor Torque |
Approximately 20 ft-lbs continuous; 50 ft-lbs peak |
| Drive Electronics |
Industrial grade, off-the-shelf brushless motor drives for each axis with custom designed interface card |
| Telescope Control Software |
PlaneWave Interface (PWI4). Incorporates PointXP mount modeling software by Dave Rowe. Provides HTTP and ASCOM control interfaces. MaxIm DL is required for camera control when building a pointing model within our PWI4 software. |
System Performance
| Pointing Accuracy |
<10 arcsecond RMS with PointXP Model |
| Pointing Precision |
2 arcseconds at sidereal velocity
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| Tracking Accuracy |
< 0.3 arcseconds over a 5 minute period at sidereal velocity
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| System Natural Frequency |
10 Hz or greater |
Additional Accessories
Item Number
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Description
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Price
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| 200130Q |
CDK-500 (CDK20 / L-500) |
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| 600180 |
IRF90 Rotating Focuser |
++ |
| 200901 |
EFA, Focuser Accessory Control |
+++ |
In the Box
| Heating elements for dew prevention |
The heating pads on the primary and secondary mirror require the 600195 Delta-T controller sold separately |
| OTA Cover |
To protect the primary mirror and inside of the optical tube |
| Flashdrive |
Contains software and instructions for collimation and spacing the primary to secondary mirror |
| Hardware |
Six 1/2-13 x 1 1/4″ socket head cap screws to bolt the mount to the pier, or wedge
Six 1/2-13 washers
One extended length shoulder bolt for RA axis to EQ wedge alignment
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| One 16′ USB cable |
To connect the mount to the observatory control computer |
| One 120VAC power cable |
To provide power to the mount |
| Standard Allen Key set |
For tightening bolts used on the mount |
| Flashdrive |
Contains PWI4 software for mount control and instructions for installation |
| Gamepad |
Used for control of the mount tracking speeds for visual observing |
Manuals & Warranty
Planewave Warranty (one year for optical coatings and two years mechanics and electronics from the date of delivery)
Drawings & Diagrams
L-500 Pier Interface Drawing
L-500 Mount Dimensions
Instruction Manuals
L500/600 Mount Instructions
PlaneWave Interface 4 Software User Manual_V15 1.7.2021
