3.50 mm TRS jack, board-guide equipped
The STX-3120-3B-284C is a 3-conductor (TRS) female phone jack from Kycon's STX-3120 series, accepting standard 3.50 mm (1/8") mini plugs. It mounts through-hole right-angle with kinked pins for solder retention and includes a board guide for alignment during assembly.
Tin-plated contacts, no internal switch
Contact plating is tin on brass and phosphor bronze — suited for signal-level audio duty where mating cycles are moderate. The jack contains no internal switch, so the circuit path is always closed through the tip, ring, and sleeve when a plug is inserted.