The tag 'parrot' is only used once. This is the project:
HAM radio parrot repeater
This small interface contains a VOX, PTT and has the option to 'inject' tones generated by the Arduino
This prototype is a first setup to use the Arduino (Uno) as a parrot repeater. Diagram, PCB and sketch have enough room for improvement, but that's the nice part for (radio) amateurs. Nevertheless: this one works fine, so every improvement will only fancy up the thing.
Enjoy!!