User Manual

DRAFT RF Front End System Integration Manual
044-05082 Rev. A
1-1
March 2001
Section 1 General Discription
1-1 Introduction
This manual contains information and procedures for installation, operation, and maintenance of
the Radio Frequency Front End (RFFE) Multi-Carrier Power Amplifier (MCPA) System. This
manual is organized into sections as follows:
Section 1.General Description Appendix B: Amplifier Power Setting Procedure
Section 2. Installation Appendix C: General Site Survey Form
Section 3. Operating Instructions
Section 4. Principles of Operation
Section 5. Maintenance
Section 6. Troubleshooting
1-2 General Discription
Designed to compensate for cable loss due to long cable runs, the RFFE uses an AB amplifier
that utilizes a pre-distortion technique for linearization (see figure 4-3 for the amplifier block dia-
gram). Designed as a two unit system and equipped with a space diversity path to reduce fading,
the RFFE operates in the PCS frequency range of: 1850MHz to 1910MHz (receive) and 1930MHz
to 1945MHz (transmit): The system consists of.
• The Masthead Unit (MHU)
• The Masthead Unit Interface (MHUI)
1-2.1 The Masthead Unit
The primary function of the MHU is to provide maximum RF output power (not to exceed 100
Watts) with multiple CDMA carries into a matched 50 Ohm load while maintaining the spectral re-
growth and spurious requirements (see table 1-2). Supported by a mounting frame (see figure
1-2), the Mast Head Unit (MHU) is mounted on the antenna tower near the antenna and consists
of three modular components; the common box and two RF transmit (Tx) modules. each module
is encased in a weatherproof (NEMA 4) housing (refer to table 1-2 for environmental specifica-
tions).
1-2.1.1 The Common Box
The common box (see figure 1-4) connects to both Tx modules via blind mate connectors (refer to
figure 1-1 and table 1-1). It houses a redundant LNA path, two input duplexers, two output du-
plexers, two 27VDC (scalable up to 1200Watts) power supplies, and a control board.
1-2.1.2 The Transmitt Modules
Powered by 220VAC from the host breaker panel, the two RF transmit modules are used for re-
dundancy in the system. Each module houses one MPA9505-55 MCPA and a rectifier circuit that
reduces the 220VAC to the 27VDC required to operated the amplifier. To aid in maintaining the
system’s operating temperature, each amplifier is mounted on a heat sink and is equipped with a
220VAC variable speed fan. Refer to figure 1-5.
The MHU connects to the Masthead Unit Interface (MHUI) by two RF cables, and one CONTROL
cable. Refer to figure 2-6.