This is a simple interface that plugs into the back of Motorola GM950 radios to break out:

• Flat RX audio
• Flat TX audio
• The PTT line
• Open collector COS or TOS (depending on configuration)

The intended use for this project is to connect a link transceiver to the EchoLink network. The interface was designed for the GM950 series but may also work with GM350 (untested). It was designed with KiCad 5.1.5 as a quick replacement for a failed unit. The first version was milled in-house during the COVID-19 lock-down, thus traces are extra wide and on a single layer to ease the manufacturing process.

This is provided as is under the CC BY-SA 4.0 license. In particular, no BOM is provided but the schematic is straight forward. SMD component sizes are 0805. Please refer to the schematic for modification of the suggested resistor values, depending on your application.