Baofeng UV-5R Documentation page 20

connectors
The (Chinese) Radio Documentation Project
To attach accessories such as headsets, speaker-mics or programming cables, align the
connecors and push in fully.
The fit isn't always perfect on cheap cables and connectors and may require a bit of force
to wiggle them in completely.
Make sure the radio is off before attaching any accessories.
12 Getting to know your radio