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HARRIS
888-9058-001
WARNING: Disconnect and lockout AC primary power prior to servicing
16
Another use will be to retrofit existing analog transmitters to digital service. These
PAs will continue to use the 12 or 17 visual PA module configuration as the digital
power amplifier.
Platinum Series
transmitters employ rugged field effect transistors (FETs), parallel
amplifier modules, multiple power supplies, and a high-resolution flat display screen for
monitoring.
The control and monitor system includes storage of fault events with time, date, and
description. VSWR foldback automatically reduces power during high VSWR operation,
such as that encountered with antenna icing.
Available options include dual exciters, an automatic exciter switcher, and redundant
control power supplies.
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. 45kWunits 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.
1.2.1 AC Power Distribution
Refer to AC Power Distribution drawing for the following discussion. 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.