Section I; Introduction; General Description; Ac Power Distribution - Harris Platinum Series Technical Manual

Introduction

1.1
This section contains a general description of Platinum Series
television transmitters, their control systems, signal paths, and
system specifications.

General Description

1.2
Platinum Series transmitters employ rugged field effect tran-
sistors (FETs), parallel amplifier modules, multiple power sup-
plies, and a high-resolution flat display screen for metering.
The control and monitor system includes storage of up to 32 fault
events with time, date, and description. VSWR foldback auto-
matically reduces power during high VSWR operation, such as
that encountered with antenna icing.
Available options include dual exciters and an automatic exciter
switcher, redundant drive chains, and 20% aural power on some
models.
Each transmitter consists of a control cabinet and one or more
amplifier cabinets. Transmitters from 1-10 kW have a single
amplifier cabinet containing the aural path, the visual drive chain,
and the visual final. 20 kW transmitters have two amplifier
cabinets like those used in the 10 kW transmitter.
15 kW transmitters have two amplifier cabinets: one for the aural
path and visual drive chain, and one for the visual final. 30 kW
transmitters have one cabinet for aural path and visual drive
chain, and two 15 kW visual final cabinets. 45 kW units have two
aural path/visual drive chain cabinets and three 15 kW visual
finals. Finally, 60 kW transmitters have six cabinets, doubling
the 30 kW architecture.
In transmitters with multiple visual amplifier cabinets, outboard
hybrids are used to combine the outputs of the visual finals.
Optional notch or hybrid diplexers are available for all models
to combine aural and visual signals to permit using a common
antenna system.

AC Power Distribution

1.2.1
Refer to AC Power Distribution drawing for the following dis-
cussion. Each cabinet has its own AC power source. Control
cabinet breaker CB-1, located behind the control panel left of the
controller boards, protects the wiring in the control cabinet (see
Figure 1-1). A phase monitor guards against low voltage, loss of
one phase, and reversal of the phase sequencing. Line voltage
samples are provided for the system monitor. All logic supplies,
exciter power and fan in the control cabinet are controlled by
CB-1.
Each amplifier cabinet's AC power is fed through CB-1 to the
logic supply (see Figure 1-3). AC Contactor K-1 feeds the 50 volt
supplies and fan breaker CB-2 (see Figure 1-4). Aux relay K-2
activates the AC contactor through commands from the slave
controller.
888-2365-001
WARNING: Disconnect primary power prior to servicing.

Transmitter Control System

1.2.2
See Figure 1-5. The control system for the transmitter consists
of a main controller mounted in the control cabinet, plus individ-
ual slave controllers mounted in each amplifier cabinet. Data
from the system is interfaced through the monitor board to the
display controller, and shown on the front panel flat display
screen as bar graphs and numerical readings.
Transmitter ON/OFF, LOCAL/REMOTE, and power
RAISE/LOWER switches are located on the control cabinet, to
the right of the display panel.

Display Panel

1.2.3
The monitor system samples each cabinet and gathers all of the
status and analog data for the display. The Monitor board inter-
faces the main and slave controller information to the display
controller. The display is menu-driven, with "soft keys" below
the display panel for accessing and maneuvering through the
various pages of information.
A HELP key below and to the right of the display panel provides
a short description of the page of information being viewed, to
assist non-technical personnel in interpreting the data.

Fault Indicators

1.2.4
Fault lamps are located below the display and switches. Each
light, when illuminated, indicates a problem in one of the follow-
ing areas: exciter, VSWR fault, VSWR foldback, power supply,
controller, air, door, failsafe, phase loss, module, monitor, visual
drive fault, aural drive fault, and external interlock.

Main Controller

1.2.5
The transmitter main control unit provides a central point for
control and monitoring the entire system. The main controller
interfaces with the slave controller(s) for the amplifier cabinets'
ON/OFF commands, and with the exciter for power
RAISE/LOWER commands.
Peak detectors collect aural and visual RF samples and send them
to the main controller for power metering. The main controller
also directs VSWR foldback action.
The main controller has a battery backup to restore the transmit-
ter to its previous operating condition after a temporary AC
power failure. A power down timer will automatically turn the
transmitter off if the power is not restored within approximately
two hours.
Remote status and analog outputs are provided by the main
controller to a series of D connectors in the rear of the control
cabinet.

Slave Controllers

1.2.6
The slave controllers are mounted in the upper left-hand slot of
each amplifier cabinet. Each is responsible for controlling and
monitoring its PA cabinet. The controllers interface the cabinet
to the main controller and monitor in the control cabinet.

SECTION I

INTRODUCTION
1-1