If you are experiencing a loud "Pop" more likely a jumper is set on position J9 try removing this Jumper from the station and try again. On Push-To-Talk mics, like the ones we ship with VP4Xs, the PTT on the mic actually physically disconnects the mic itself and J9 will never need to be set so it should be completely removed.
In this diagram, the J9 jumper is the one circled and labeled Mute Enable Jumper:
In this photo, circled is what the J9 jumper looks like when it is on the board. Again, you will want to make sure this jumper is removed if you are experiencing popping noises: