This interface allows Icom radios equipped with an RJ45 PTT connector and a 3.5 mm speaker output to be connected to a Raspberry Pi, enabling remote control and operation over a Radio over IP (RoIP) system.

This board attenuates the speaker output to match the line-level input of the Raspberry Pi. It also attenuates the Raspberry Pi’s line output to make it suitable for the radio’s microphone input.

Note: The Raspberry Pi only provides a single audio jack output. Therefore, I use a low-cost USB sound card (input + output), purchased online for around $4.

The software was developed in-house with the help of AI tools. It remains fairly basic and has not been published. A minimal web interface allows remote control of the PTT (ON/OFF) when the Raspberry Pi is connected.

The voice transmission (audio TX) part is still under development. However, the hardware side is complete, tested, and fully functional.