What This Ferrule Does in a D-Sub Assembly
The TE Connectivity 3-747579-0 is a shielded outer ferrule from the AMPLIMITE HD-20, HDE-20, HDP-20, and HDP-22 series — the standard D-subminiature connector family. It clamps over the cable shield braid at the back of a D-sub backshell, completing the 360° shield path from the cable to the connector shell. The stepped inner profile fits the three common shell sizes — DB9, DB15, and DB25 — so one ferrule covers the whole harness family. It is an accessory, not a signal-carrying component; the ferrule itself carries no electrical rating beyond the shield continuity it provides.
Shielded Construction and Series Compatibility
The ferrule is explicitly listed as shielded, meaning it is designed to maintain the EMI/RFI shield integrity when mated with a shielded backshell and cable. It is compatible with any AMPLIMITE HD-20, HDE-20, HDP-20, or HDP-22 D-sub connector — the same family that covers standard-density and high-density shell layouts. The 9 ~ 25 position range maps directly to the shell sizes: DB9 (9 positions), DB15 (15 positions), and DB25 (25 positions).