Specifications
Section C
Driver Combiner Motherboard (A5)
C.1 Introduction
This section describes the DriverCombiner Motherboard. Topics
include function, location, detailed circuit description, trou-
bleshooting, and removal/replacement.
Following this section, the Buffer, Predriver, and RF Drivers will
be discussed since they are boards that plug-in to the Driver
Combiner Motherboard.
NOTE: For more information about the RF Driver Section, refer
to the Overall System Theory Section.
NOTE: Parts List for this board is in Section VII.
C.2 Function
The purpose of the Driver Combiner Motherboard is to provide
the input/output connections for the Buffer, Predriver, and 14 RF
Driver amplifiers. Other functions include Predriver Switching,
Buffer and Predriver RF Sense, and RF Driver Combining.
C.3 Location
The Driver Combiner Motherboard is located in the upper right
PA compartment. (SEE VIEWS 10 & 15)
C.4 Detailed Circuit Description
Refer to Driver Combiner Motherboard Schematic Diagram
(839-7930- 504), and Figure C-1 Driver Combiner Motherboard
for the following discussion.
C.4.1
Buffer Amplifier Connections - J1
C.4.1.1 RF Input
The signal from the RF Interface board enters the Driver Com-
biner Motherboard at J30-1, and is routed directly to the Buffer
Amplifier RF input at J1-15.
C.4.1.2 Power Supply
A +60VDC line from the RF Amp Power Supply passes through R37
& tapped resistor R2, and enters the Driver Combiner Motherboard
at J32-3. It is connected to the Buffer Amplifier at J1-41, and can be
varied from 20 to 45VDC by R2, Buffer Voltage Adjust.
C.4.1.3 RF Output
The Buffer Amplifier RF output for Section A enters the Driver
Combiner Motherboard at J1-49 and is routed to J2-49.
The Buffer Amplifier RF output for Section B enters the Driver
Combiner Motherboard at J1-53 and is routed to J2-53.
C.4.1.4 Buffer RF Sense
Peak detectors provide a Buffer Amplifier RF Sense signal for
Section A and Section B outputs to fault and overload circuits on
the Driver Encoder board.
Figure C-1. Driver Combiner Motherboard
888-2339-002 C-1
WARNING: Disconnect primary power prior to servicing.