ADC ClearGain User Manual page 12

ADCP-75-154 • Issue 3 • August 2006
2.2.1 Installation of the MHU on the Mast
Note: All hardware is specified in metric units.
Before any installation, check that the ClearGain MHU has no visible damages or defects.
Note: The ClearGain MHU must always be installed so that the connectors point
downward. Not more than a 45-degree installation angle is recommended.
1. Place the MHU so that the bracket can be attached to the unit.
Note: The threads are sensitive to damage.
2. Place one half of the bracket (the half with the lifting hook) behind the MHU using two
M8 bolts or long bolts.
3. Fasten the long screws, nuts, washers, and brackets.
4. Before going up to the mast, verify that the remaining washers and nuts are not left on the
ground. Temporarily remove the connector protector plugs, inspect the 7/16 DIN connectors
for damage, and return the connector protector plugs to their respective connectors.
5. Place the ClearGain MHU as close to antenna as possible. Attach the rest of the fasteners
to the bracket system. Fasten the remaining washers and nuts. Verify that the MHU is
tightly in place.
2.2.2 Installing the MHU Ground Cable
Good grounding of the ClearGain MHU is important to protect the unit against voltage surges.
These surges could be caused by, for example, lightning. Install the ground cable as follows:
1. Connect the ground cable to MHU side using M5 attachment screw and washer.
2. Connect the other end of the cable to a good ground (site ground) with a reliable joint.
GROUNDING and BONDING CONSIDERATIONS
• Grounding is very important in tower applications. Shipped with each MHU, is a #6 AWG,
3-foot 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).
• Following local grounding practices the single hole lug is usually re-terminated by the
tower crew with a double hole lug and bolted to 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.
• If ground cable length is too short, customer may make a longer ground cable (#6 AWG)
as long as all the mechanical connections are tight and clean.
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© 2006, ADC Telecommunications, Inc.