Model: 5% Off - Free Ship (Lower 48) Category:

Use Coupon Code “Hamvention2020”


Virtual Hamvention Spectacular


Additional information

Rotator Type

Yaesu G-800, G-1000, G-2700, G-2800, Alfa Spid, Pro-Sis-Tel 2051/61D, Others (contact us for others)


None, WiFi (+$116.00)


RT-21 DC Powered Rotator Controller:

The RT-21dc requires an external power supply capable of operating your rotator of choice. We recommend using:
Yaesu model 800, 1000, 2800 DC rotators – Single 13.8 to 24 VDC @ 4A
Alfa Spid, all models – Single 13.8 to 24 VDC @ 4A
TIC Ring – Single 24 VDC supply @ 4A, more if two motors

Higher voltage motors may be accomdated with a separate 13.8V supply < 500mA for the controller, and a higher voltage DC supply (up to 48VDC) for the motor.

AC motor units may be used if a separate source of appropriate AC voltage (isolated from ground) can be supplied.

The RT-21dc can be configured for all of the same position indicator variations as the standard controllers.

RT-21dc Features:
  • PWM speed control effective for most rotator types
  • 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 two 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, brake 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
  • Special advanced options for custom applications
  • Supports “Shortest Route” for rotators with more than 360º  rotation capability
  • Comprehensive SETUP Utility software included
  • Free application software for satellite tracking, and remote control and rotator sharing using standard TCP/IP (Internet)


RT-21dc Specifications:


  • Approx 4” x 8” x 7” HWD
    (Not including rear terminal strip)
  • Approx 3.5 lb – Shipping = 6 lb

Input Power

  • 13.8 to 24 VDC Controller and Rotator
  • Separate 13.8 to 24 VDC for Controller, and up to 48 VDC for Rotator
  • SIngle Supply fuse provided, separate motor power must supply external fusing.


  • High contrast Yellow-Green backlit FSTN LCD
  • Eight brigtness 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)

External Relay Control

  • CCW and CW DC relay control (12V or 24VDC relays)
  • various configurations

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)
  • 2-Bit rotary relative encoder (special order)
  • 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  (Relay Control)

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 Systems)
  • Counter Range Error (Pulse counter)
  • 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-21 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-21
  • 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-21 Documents:


Download RT-21 Brochure


Download RT-21 User Manual