Model: RT-21pp Category:

Rotator Controller, Prop Pitch

From $689.00

Special version of the RT-21 for K7NV Prop Pitch Rotators and systems. Contains 26VDC 10A rotator power supply and extra heavy duty components to match. For cable runs up to 300′. This unit can be utilized for any 2 or 3 wire DC motor system requiring 24-26VDC @ 10 A utilizing pulse or potentiometer position feedback.

Includes magnetic pulse switch, USB cable, and printed manual. Unit is configured to order. Software and other resources available on the website.


Additional information

Weight 12 lbs
Dimensions 12 × 12 × 6 in
AC Mains

115 VAC, 230 VAC (no power cable)

Magnetic Switch

No Proximity Switch, Add Switch ($40.00)

Divide Ratio

Small – 9576:1, Medium – 7063:1, Large – 7056:1, X-Large – 7497, X-Large – 5920, Don't Know – Other, Potentiometer

Deluxe Upgrade

Standard Unit, 'D' Deluxe Version (Special Order) (+$140.00)


RT-21 Prop Pitch

The RT-21pp is designed specifically for Prop Pitch Rotators from K7NV Systems.  The unit is similar to the RT-21 except:

  • Runs DC motors in the 24-28V range only, 2 or 3 wire motor configurations
  • Heavy Duty 10A custom transformer
  • Special HD main board with 20A relays, and hi capacity 35A main drive FET


RT-21pp Description:

The RT-21pp is a special version of the RT-21 specifically developed for use with K7NV Prop Pitch rotators and systems. Contains 26VDC 10A rotator power supply and extra heavy duty components to match. For cable runs up to 300′. This unit can also be utilized for any 2 or 3 wire DC motor system requiring 24-26VDC @ 10 A utilizing pulse of potentiometer position feedback.

Why upgrade Prop Pitch system to an RT-21pp?

Adds USB and/or RS-232 control
Allows Master/Slave or Counter-rotate with any RT-21 models
Adds high-resolution digital display
Adds Point & Shoot hands-off operation
Yields 1/10th degree resolution and computer control for high accuracy EME or other UHF/SHF work application
adds PWM speed control and gradual start’/stop to your system greatly reducing tower and other twisting stresses for your large arrays

The RT-21pp manual contains details on setup, hookup, and calibration for Prop Pitch rotators and other 24VDC motors. Additional resources are available from Green Heron in the form of applications notes, that detail less common or custom requirements.


RT-21pp Features:
  • PWM speed control
  • Precision ramp control for smooth starts and stops
  • Manual control using CCW and CW buttons
  • Point and Shoot knob for set and forget operation to 1º precision
  • The ability to correct for mast slippage using OFFSET
  • Computer control via RS-232 or USB to 1/10º  accuracy
  • Precision heading accuracy up to 1/10thº
  • Master/Slave links 2 or more RT-21 for stacked arrays or turning multiple systems to the same heading
  • Counter-Rotation for single mast systems with rotator above a rotator
  • Fully programmable settings for speed, ramps, reversal delay, limits and more
  • Two alternate OFFSETs for offset antenna directions on the same mast
  • Elevation and EME modes optimize for Az/El systems and tracking
  • Limits rotation for side mounts, and allows up to 720º  total rotation for supporting rotators
  • High contrast yellow-green backlit LCD with 8 brightness levels and auto-dim
  • Many built-in safguards to protect your system from over-rotation due to internal or external failures
  • Rugged .080 aluminum chassis houses CCS rated power components and 7 lb transformer
  • Special advanced options for custom applications
  • Supports “Shortest Route” when setup with limits > 360 degrees
  • Comprehensive SETUP Utility software included
  • Free application software for satellite tracking, and remote control and rotator sharing using standard TCP/IP (Internet)


RT-21pp Specifications:


  • Approx 4” x 8” x 7” HWD
    (Not including rear terminal strip)
  • Approx 10 lb – Shipping = 12 lb

Input Power

  • 115/230 VAC 50/60 Hz
  • Standard IEC power connector
    and 5x20mm GMA fuse


  • High contrast Yellow-Green backlit FSTN LCD
  • Eight brightness levels w/auto-dim

Front Panel Controls

  • CCW, CW and CANCEL buttons (Operating)
  • SAVE, CHANGE, SETUP buttons (Setup)
  • Point and Shoot knob (340º = full rotation)

Motor Power
(26VDC@ 10A)

  • Three wire ( CW, CCW and COM)
  • Two wire (polarity reversal)

Operating Modes

  • Normal, Master/Slave, Master/Counter Rotate, Slave/Counter Rotate, Debug, Alt Offset

Position Feedback Mechanisms Supported

  • Potentiometer 150 Ohm to 10 kOhm
  • Variable resistor 500 Ohm (Others accommodated with minor modification)
  • Proximity/reed switch or Hall effect up to 64 pulses/degree (divide ratio  up to 23,500)
  • Others possible

Position Accuracy

  • Up to 1/3º for potentiometer
  • Up to 1/10º with proximity/reed switch

Brake and Reversal Delays

  • 0 to 6 Seconds

Soft Limits

  • +/- 180º from normal stop
  • Restricts rotation to zero or opens to 720º

Motor Speed Control (PWM)

  • 10% to 100% in 10% steps with 10 selectable start/stop ramp settings
  • 100% no ramps

Computer Control

  • Compatible with all DCU 1 enabled programs
  • Expanded Ppotocol for GH Tracker and SETUP UTILITY (See manual)


  • User changeable in minutes with no soldering


  • No Motion feedback
  • Pot out-of-range (Pot Option)
  • Counter Range Error (Pulse Option)
  • Industrial rated Transient Voltage Suppressors on all external terminals

Rear Panel

  • 8 Position barrier strip #6-32
  • Ground stud #6
  • Cable strain relief
  • USB-B
  • DB-9 RS-232


  • Limited warranty, 1 Year parts and labor


RT-21pp Set-up Utility:

The RT-21 Setup Utility allows you to manage configuration options and optimize other controller settings from your PC.

It also enables you to . . .

  • Change the vanity boot message
  • See a graphic representation of the rotors rotation range
  • Change the rotors rotation range
  • Modify the security setting
  • Change the NO-MOTION motor timeout
  • Perform Auto-Cal on many rotor types
  • Save rotor settings to files
  • Restore rotor settings from files
  • Test computer rotator control

GH-Setup Utility Chart - Green Heron Engineering

GH Tracker – Satellite Tracking

  • Precision 1/10º automatic control
  • Optimizes your tracking program for the RT-21pp
  • Interfaces with WSJT, Nova and others

GH Tracker Satellite tracking - Green Heron Engineering

GH Everyware – IP Networking for your GH Controllers

  • Remotely control your rotators over the Internet
  • Share rotators on your network

GH Everyware IP Networking - Green Heron Engineering



RT-21pp Documents:


Download RT-21pp User Manual




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