RJ45 Jack for Legacy Cat3 Installations
This jack is rated Cat3, which limits its usable frequency range to 16 MHz — fine for 10BASE-T and voice (POTS) but not for 100BASE-TX or Gigabit Ethernet. A Cat5e jack, by contrast, is specified to 100 MHz and supports 1000BASE-T. If the cabling plant is already Cat5e or better, this jack becomes the bottleneck; if the run is legacy Cat3 cable, the jack matches the channel performance.
Shielding and Board Retention
The shielded shell with EMI finger provides a low-impedance path to chassis ground, which matters when the jack sits near switching supplies or motor drives.