A fully isolated rig interface unit for Echolink, FreeDV/Codec2 and other digital modes. It requires just a single USB cable from the PC to the interface and a single data cable from the interface to the data port which is available on most modern rigs.


The interface includes the following features:

  • Completely surface mount technology based
  • Microcontroller controlled to allow for simpified operation
  • All connections to the radio are optically or galvanically isolated from the PC
  • Single USB interface to PC, which provides power, audio, control and data interfaces
  • Single data connection to the radio, using the mini DIN data port
  • Transmit time-out timer (software configurable time)
  • Echolink ASCII data support

Supported Modes

The interface should support any analog or digital mode that uses a sound card on the PC. This includes (but is certainly not limited to):

  • Echolink
  • PSK31
  • SSTV
  • Packet
  • APRS
  • FreeDV
  • WSPR

Please feel free to let me know of any other modes!


Version 3.0 of the interface has been manufactured and I am waiting on delivery of the boards.

Version History

  • 1.0 was manufactured and partially tested, but due to a computer issue the CAD files were misplaced.
  • 2.0 was rebuilt completely and used for testing. Testing revealed a few changed needed to be made, notably the power-on-reset for the USB hub controller was unreliable and the chosen audio transformers are unsuitable. It was also not possible for the AtMega32u4 microcontroller to assert the CTS signal on the USB CDC port.
  • 3.0 swaps the AtMega 32u4 for separate FT230XS and AtMega88 devices to allow usage of CTS, replaces the audio decoupling capacitors and transformers and drops the hardware DTMF support. It also re-adds back in the front-panel connector from version 1.0


3D Render Main Board
3D Render Front Panel 1
3D Render Front Panel 2
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Under Development
17 Oct 2020
14 Nov 2020