DuinoVox

Quote from the original designer/builder (KB9RLW): "Cheap and easy to build digital modes USB interface for Ham Radio." http://kb9rlw.blogspot.com/2016/08/cheap-and-easy-to-build-digital-modes.html

The controls are for TX Gain, RX Gain, and PTT delay (delay control mostly used when transmitting CW.)

Tested with FT8, RTTY, Packet Radio, etc. and made hundreds of contacts when hooked to the FT-757GX transceiver.