ADC ClearGain Dual Inline Tower Mounted Amplifier System - Manual (Page 9)

ADCP-75-214 • Issue 2 • September 2006
Page 3
© 2006, ADC Telecommunications, Inc.
MHU – located as close to the antenna as possible, performs the amplifier function on the
uplink signal. Three subcomponents of the MHU, two RF cavity filters, and a Low Noise
Amplifier (LNA), are involved in the amplifier function. Downlink signal is not amplified but
passed through an RF cavity filter.
PDU – located in the base station, provides DC current to power the LNAs and On/Off Key (OOK)
modem signal for use in the Remote Electrical Tilt (RET). The PDU outputs the DC current through
a front port from which it travels by way of a short linkage cable to the Bias-T. The injection of the
DC power onto the coaxial cable will not cause interference with signal transmission.
The PDU monitors the MHUs simultaneously by sensing their current draws. If any of the
MHUs fail, or if there is a cut or short circuit in the coaxial cable, the PDU sends an alarm to the
BTS. The PDU thus also monitors the condition of the coaxial cable, not just the MHU. The
PDU also has built-in lightning protection.
The PDU has a connector for RET communication with the BTS. The data bus is a two-wire bi-
directional configuration and can be used for RS-485 communications link between the BTS
and PDU. The OOK modem is AISG standard compliant.
Bias-T – located on the coaxial cable, is a passive device that physically injects DC power onto
the coaxial cable to provide powering for the MHU. Bias-T may be installed indoors or
outdoors. There are four Bias-T connector options:
• 7/16 DIN male to the BTS; 7/16 DIN female to the ANT
• 7/16 DIN female to the BTS; 7/16 DIN male to the ANT
• N male to the BTS; N female to the ANT
• N female to the BTS; N male to the ANT
A single PDU supports three dual inline MHUs (with one Bias-T required for each dual inline
MHU). The Bias-T may be plugged into either of the RF cables to power the MHU.
2 SYSTEM INSTALLATION
2.1 Installation Overview
Installation consists of three main steps:
1. Installing the MHU: mechanical attachment, coaxial cables and ground cable.
2. Installing the PDU: mechanical attachment, operation power, alarms and ground cable.
3. Installing the Bias-T: mechanical attachment, coaxial cables, power cable and ground cable.
2.2 Masthead Unit Installation
Pole mounting kits are provided for installing the MHU. See Figure 3 . Before any installation,
check that the ClearGain MHU has no visible damages or defects. Place ClearGain MHU as
close to the antenna as possible.