Cables and Connectors
Using Shielded Twisted Pair Cables
Type 1 shielded twisted pair (STP) cabling also operates with 10BASE-T Ethernet and 100BASE-TX Fast Ethernet. Type 1 STP cable consists of tinned-copper braided shield surrounding two data-grade twisted pairs of #22 AWG solid copper conductors that have individual or S-shaped shields of aluminum-backed insulating tape or metallized Mylar foil.
Note: A balanced unbalanced (balun) media adapter is required when connecting 100-ohm RJ-45 100BASE-TX ports to a 150-ohm STP cable plant. This adapter provides impedance matching between UTP (100-ohm) and STP (150-ohm) cabling.
Type 1 cable generally is used between wiring closets or from the wiring closet patch panel to the work area wall outlet.
Type 1 cable generally is terminated with an IBM four-position data connector. Nortel Networks Fast Ethernet supports 100BASE-TX Fast Ethernet over STP media through the application of a specialized balun media adapter, also referred to as a Type 1 balun (Figure B-5). When adapting 150-ohm STP cable plants for Fast Ethernet applications, balun media adapters are required at both the hub and station ends of the STP cable plant. Media adapters (such as AMP part number 558421-1) are available that plug into the RJ-45 patch cable connectors, allowing the patch cable to connect with an IBM data connector. The media adapter and patch cable provide impedance matching between UTP (100-ohm) and STP (150-ohm) cabling.
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Figure B-5. Fast Ethernet Type 1 Balun Media Adapter
Note: For additional information about AMP Type 1 balun media adapters (part number 558421-1), contact your AMP reseller or distributor. The user should verify that the combination of the STP cable plant and the impedance- matching baluns meets the requirements of the applicable LAN standard.
