Antenna switch & rotator controller

This is a two-in-one device. It can be set up to:

  • switch 7 antenna relays from a PC over USB or using transceiver band output
  • control an antenna rotator using buttons and LCD or from USB

Hardware features

  • LCD 2×8
  • 5 buttons
  • USB
  • 8-15V DC power input (can also run alone from USB)
  • 7 open-collector outputs suitable to drive 12V relays directly
  • pulse input (for rotator encoder)
  • RJ-45 transceiver connector with signals compatible with Icom and Yaesu radios

Antenna switch features

  • manual switching of 7 antennas using front panel buttons
  • PC control using OTRSP protocol via USB (eg. Logger32, N1MM and other popular applications)
  • automatic antenna selection using band output from Icom or Yaesu radio
  • switching is locked when PTT is active
  • current antenna is shown on the LCD and indicated with a LED
  • each antenna can have its own name displayed
  • each antenna can have any bands assigned

Rotator controller features

  • can learn any pulse count per rotation
  • protection against rotating too far
  • protection against missing pulse feedback
  • manual control left/right
  • rotation to desired azimuth using front panel buttons
  • PC control using GS-232B protocol

User manual

Buttons have obvious names – up, down, left, right, center one is called enter.

Power-on button commands

UP button start bootloader to load new software
RIGHT button select between antenna switch and rotator controller
DOWN button start rotator learning procedure
LEFT+ENTER+RIGHT reset to defaults

Antenna switch mode

LEFT / RIGHT switch antenna
ENTER switch to automatic mode (band data from transceiver)
ENTER long press configure antenna bands and name (hold once more to configure transceiver type)

The display presents currently selected antenna and its name. Upper right corner shows ‘M’ for manual antenna selection, ‘A’ for automated control from transceiver band output, ‘TX’ for active PTT (switching is locked).

|ANT 1  M|

Antennas can be switched using left and right buttons.

Antenna configuration

To configure a particular antenna it has to be selected first and then enter button must be held for a couple of seconds.

Arrows are displayed whenever a particular button is active. This screen shows configuration of antenna 1 and 160m band is not enabled for this antenna. Up/down buttons cycle through all bands.

|SET 1  ↑|
|160[ ]↵↓|

One of the options is called ‘NAME’ – it leads to the name input screen:

| ←→↑↓ ↵ |

Each letter can be changed using up/down buttons. Cursor is moved using left/right buttons. Enter saves the name. It is a convenient as writing an SMS on a ’90s phone, but it has to be done only once 🙂


After installing drivers the device should show up in device manager as a regular serial port:

Logger32 requires band assignment to be set first. Click “Tools”->”Setup bands and modes”.

Each band and mode has a separate “Aerial” field that is just a number from 1 to 7.

Right click on “Antenna” in the status bar and then on “Show antenna selector”.

Select the right COM port and click “Open OTRSP device”.

When connection is established the line below should turn green and the antenna should be automatically selected.

Rotator controller mode

Rotator software is based on a previous, proven design. The controller has to be first taught the pulse count and azimuths of the rotator.

Learning mode

Hold button DOWN and turn power on. The following screen will be shown for a couple of seconds:

| SETUP  |

Rotate the antenna to the furthest counter-clockwise azimuth (there is no protection at this stage!) using LEFT / RIGHT buttons. The following screens are shown:

+--------+   +--------+
|ROT MAX |   |THEN    |
|LEFT  ←→|   |PRESS  ↵|
+--------+   +--------+

When the antenna is at the furthest counter-clockwise azimuth – press enter. Repeat the same step for furthest clockwise azimuth:

+--------+   +--------+
|ROT MAX |   |THEN    |
|RIGHT ←→|   |PRESS  ↵|
+--------+   +--------+

After the pulses have been counted, azimuth values in degrees have to be put in using up/down and left/right keys, then confirmed with enter.

+--------+   +--------+  +--------+
|000°000°|   |000°000°|  |000°000°|
+--------+   +--------+  +--------+

Rotator is ready to use 🙂 LEFT / RIGHT buttons directly turn the antenna (with all kinds of protection). UP / DOWN buttons change azimuth setpoint the antenna will be automatically rotated to. From PC’s side the device speaks GS-232B protocol.

|POS 000°|
|SET 000°|


Software and design files

Feel free to contact me if you want to build one (I still have some PCBs left) or have any questions 🙂

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