What This Ferrule Does in a D-Sub Assembly
The TE 2-747579-7 is a shielded outer ferrule for AMPLIMITE series HD-20, HDE-20, HDP-20, and HDP-22 D-subminiature connectors. It fits shell sizes from 9 to 25 positions, making it a single SKU that covers the common DB9, DB15, and DB25 cable assemblies. The ferrule is the metal clamp that cinches the cable jacket behind the backshell — the shielded variant provides a 360° EMI bond between the cable braid and the connector shell, which is what keeps radiated emissions inside the harness and out of the enclosure.
Shielding — the Key Differentiator
Not every D-sub ferrule is shielded. The 2-747579-7 is explicitly listed as shielded, meaning the ferrule body itself completes the ground path from the cable braid to the backshell. In a standard unshielded ferrule the braid is left unterminated or requires a separate grounding strap. For any assembly that needs to pass radiated emissions testing — industrial controls, medical equipment, or telecom racks — this part saves a secondary grounding step.
Compatibility — Which Connectors It Fits
The ferrule is listed for use with AMPLIMITE series HD-20, HDE-20, HDP-20, and HDP-22. The 9 to 25 position range means the same ferrule works on a DB9 or DB25 shell.