User's Manual

APPLICANT: MOTOROLA EQUIPMENT TYPE: ABZ89FC4829
User / Operational Manual
Functional Description / Operation of Modules (Draft)
EXHIBIT D1-6
Power Amplifier Module Overview
The Power Amplifier (PA) is a convection-cooled RF power amplifier. It accepts a low-level modulated RF signal
from the Exciter Module and amplifies the signal for transmission via the site transmit antenna. The output power
is continually monitored and regulated by a feedback and control loop, with a power output control voltage being
generated by the transmitter control circuitry located on the PA Input/Output boards.
Overview of Circuitry
The Power Amplifier contains the following sub-circuits:
• Intermediate Power Amplifier (IPA) – hybrid substrate amplifier stage which accepts low-level input from
Exciter Module, amplifies the signal, and outputs a 0 W to 10 Watt RF signal
• Butterfly Module – hybrid substrate amplifier stage which accepts output from IPA Hybrid and provides
final amplification to 50 Watts (maximum)
• Directional Coupler/Power Detector/Low Pass Filter – couples amplified RF signal to transmit antenna
connector; also generates dc voltages proportional to forward and reflected power for use in TX power
control loop; provides harmonic suppression for the station
• Dual Circulator (optional) – provides isolation between Power Amplifier output and transmit antenna
• Temperature Sense Circuitry – provides variable resistance signal proportional to heat sink temperature;
signal is monitored by the PA power control circuitry
Input and Output Connections
The following shows the PA input and output external connections.