Stray Signals

Portable Repeater Controller

This microprocessor-based Portable Repeater Controller was designed to quickly build a fully functional repeater ‘in the field’ in less than no time. Due to its universal design it can be used all the way from classroom instruction to 24/7 repeater operation. A fully functional amateur radio repeater system is created by just connecting two radios, an antenna, a power supply and optionally filters.

Examples of the use the Portable Repeater Controller are two amateur radio repeaters PI3ZAZ and PI6ZAZ, and a mobile repeater station for mountain rescue activities by the Swiss Alpine Rescue organization.

The Portable Repeater Controller is designed by Leo PA0LEZ and Ivo PA1IVO and is made available via Emco Electronics.




  • Amateur radio shows and events
  • Calamity and disaster communications
  • Education and training in repeater usage
  • Quick backup for existing repeaters
  • Part of fully functional 24/7 repeaters



  • Connect almost any receiver or transmitter (3.5 mm stereo connectors)
  • CTCSS for RX and TX (only when supported by transceivers)
  • 1750 Hz repeater activation
  • Internal or external squelch system
  • On-the-fly morse code generation for beacon and/or call (reduced volume during voice)
  • Time out timer
  • On and off timers for pre-scheduled operation
  • Temporary PTT block for antenna maintenance
  • Remote control test features
  • Supply voltage monitoring (7-30 V DC)
  • Smart energy saving power regulator, plus selectable LCD time-out
  • Electronically adjustable signal levels by four digital potentiometers
  • Real-time ADC audio level reading
  • AUX connector for extra set of remote buttons
  • Two multi-function I/O pins for remote controlled digital outputs or status info
  • Field serviceable by through-hole PCB design
  • User upgradable firmware (with free Windows software tool)
  • 5V TTL UART interfacing (e.g. PC, laptop or Raspberry Pi)
  • Open communication protocol for configuration and control
  • Free Windows software for monitoring and configuration

Configurability and remote control

Almost all repeater controller settings are user configurable, which enables repeater builders to create a fully tailor-made system, based on the needs, and of course, personal taste:


  • Up to five different user-programmable calls (max. 15 characters, spaces allowed)
  • Beacon and call speed (WPM), tone (Hz) and interval (minutes), enabled/disabled
  • Roger beep tone (Hz), character, enabled/disabled
  • CTCSS tone RX and/or TX (67.0 – 123.0 Hz), enabled/disabled
  • 1750 Hz repeater activation, enabled/disabled
  • Selectable configurability per RX channel (main or sub)
  • And many more configuration items …

Configuration settings can be made in four different ways, where the combination of these four configuration options creates a flexible and versatile system:

  1. With a PC connected via the serial interface. By storing different configurations on a PC, different repeater configurations can be activated with just a few mouse clicks.
  2. DTMF remote control via the main receiver input.
  3. DMTF remote control via a sub-band receiver input, creating a private configuration channel. Up to four controllers are addressable and can be connected to a single command receiver.
  4. Locally on the controller, without any additional equipment, by using the LCD and the high quality navigation buttons. In this way, last minutes changes are possible anywhere, anytime.


PCB width x height: 162.8 x 75 mm. See also the PCB Mounting details document.

Licence requirements

Please check your local amateur radio regulations if (additional) licences are required to set up your repeater system.

Integration Support

We are happy to share our extensive knowlegde about building repeater systems with you. Therefore, Emco Electronics offers free initial integration support to help setting up your (portable) repeater system with a Portable Repeater Controller (the initial integration support consists of e-mail correspondation in English or Dutch).


  • Instruction Manual (pdf) for the Portable Repeater Controller (firmware version 2.0).
  • Serial Communication Protocol Specification (pdf) which gives you all the details if you want to write your own monitoring and configuration software.

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