Stepped Ferrule That Covers Three Shell Sizes
The TE Connectivity 3-747579-4 is a stepped outer ferrule for the AMPLIMITE HD-20, HDE-20, HDP-20, and HDP-22 D-subminiature connector series. This single ferrule design accommodates DB9, DB15, and DB25 shell sizes — the stepped profile lets it seat correctly on each shell diameter without needing three separate part numbers on the BOM. It is shielded, meaning the ferrule provides a continuous ground path from the cable braid to the connector shell when used with the matching backshell hardware.
What It Fits and Where It Goes
The ferrule is designed for use with the AMPLIMITE HD-20, HDE-20, HDP-20, and HDP-22 series D-sub connectors. It accepts cable entry through the backshell and crimps or clamps over the cable jacket and shield braid. The stepped inner diameter matches the rear of the connector shell — 9 uses the smallest step, 15 the middle, 25 the largest. The 9 to 25 position range listed in the spec corresponds to the three shell sizes this ferrule covers.