Missable achievement.
In the first part of the game, after the tutorial, you will come across a campfire. The radio is sitting near it. Pick it up and just hold onto it for 3 minutes for the achievement to unlock (you can pick it up and hold it in your off hand while you walk around and do stuff with your other hand).
I believe the time does not have to be contiguous, so if you drop it you can pick it up again without having to start the timer over.