ADCP-75-214 • Issue 2 • September 2006

GROUNDING and BONDING CONSIDERATIONS

•Grounding is very important in tower top applications. Shipped with each MHU, is a 4mm (#6 AWG), one-meter (39-inch) ground cable with single hole crimp lug connectors on both ends. Installation hardware is provided to attach one end to the MHU.

•Keep ground wire as short and direct (no loops or knots) as possible, secure it to a good ground point (metal to metal).

•Always follow local grounding practices. The single hole lug is typically used to attach a dedicated tower ground bus.

•In the absence of a dedicated ground, the tower structure itself can be used by using a exothermic weld joint (not very common) or a mechanical ground clamp. If a clamp is used, it must be very tight and protected from corrosion effects with a corrosion preventative compound. It is recommended that the ground integrity/resistance at any mechanical junction be checked during periods of regular tower maintenance. Always follow local grounding practices.

•If the ground cable length is too short, customer may make a longer ground cable using 4mm (#6 AWG) wire as long as all the mechanical connections are tight and clean. Keep ground cables as short as possible.

2.2.2Installing Coaxial Cables

Caution: Before connecting any coaxial cables, ensure that the BTS transmitter output is turned off and that precautions are taken to ensure that the transmitter cannot be activated during the equipment installation.

Four short coaxial jumpers should be pre-made. Two will connect the BTS ports to the hard line and the other two will connect the ANT ports to the antenna.

Caution: Remote Electrical Tilt (RET) connector on MHU must be covered with protective cap if a cable is not connected to meet IP65 rating.

Most installations require four good quality flexible coax jumpers, normally terminated with 7/16 DIN-7/16 DIN connectors. Check gender of hard line and determine if antenna pigtail is present, adjust accordingly for a correct match.

The coaxial feeder that runs from the base station to the antenna should be attached to the BTS port of the MHU using a jumper cable. The reason for the jumper cable is to ensure that mechanical forces caused by temperature change will not damage the MHU connectors. Tighten connectors to 25–30 Nm (18.43–22.13 ft. lbs.) torque.

To improve connection reliability the connector joint can be protected. This is done, by installing specific weatherproof tape over the cable connectors. Loose cable should be secured to the tower using cable brackets.

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© 2006, ADC Telecommunications, Inc.