System Description Chapter 2

10-kW UHF Transmitter with Chapter 2, System Description
Feedforward Driver
840A, Rev. 0 2-3
two separate power supplies: the control
power supply and the bias power supply.
The control power supply produces the
±12 VDC to the metering circuits (peak
detectors) in the 10-kW amplifier as well
as the fault sensing boards, differential
buffer boards, and control logic boards in
the metering control panel. The bias
power supply produces the -80 VDC bias
voltage to the tube. R1, the bias voltage
adjustment, is located behind the
metering control panel. It sets up the
idling current (1.5 amps), no RF drive, by
adjusting the bias voltage. The (A3)
filament power supply assembly (1299-
1107) produces the 5.2 VDC to the
filament of the tube. The 10-kW
assembly also has (A16) a blower
assembly (1293-1325) that provides the
coolant air flow to the tube mounted in
the cavity assembly.
The RF output of the 10-kW amplifier at
(A2-A1-J2) is fed through a 3-1/8"
hardline to (A2) an output coupler (1020-
1043) that provides a reflected power
sample for fault and VSWR cutback
protection. The output at (A2-A2-J2)
connects to two UHF trap filters. The trap
filters screen out the -3.58-MHz, -4.5-
MHz, +8.08-MHz, and +9.00-MHz
intermodulation products as well as the
second visual harmonic frequency. The
output of the trap filter is fed through
(A18) the output coupler (1020-1002)
that provides a reflected and forward
power sample to (A19) the visual/aural
metering assembly (1162-1402) for
metering purposes. The output of the
coupler is then fed to the antenna.
The visual/aural metering assembly
consists of (A1) a single peak detector
board (1162-1403) for the reflected
output metering. It also contains (A2) a
visual/aural metering board (1161-1103
or 1161-1115) for aural output and visual
output power levels and reflected power
level for VSWR protection.
2.1.3 (A3) High-Voltage Power
Supply Assembly, 208/240 VAC
(1068022; Appendix A)
The (A3) high-voltage power supply
assembly, 208/240 VAC (1068022),
provides the 10-kW amplifier, through
TB4, with the AC voltage that the
assembly needs to operate. It also
supplies the AC needed to operate the
blower assembly, through TB6, and the
high-voltage, using 18 AWG 29-kV
rubber insulated wires, needed to
operate the tube in the 10-kW amplifier.
The high-voltage power supply produces
the 5000 VDC at 4.00 amps, maximum
current (black picture), or 1.5 amps
idling current (no RF drive applied) for
the plate (anode) of the tube. The
assembly contains (A1) the high-voltage
transformer (1293-6103), (A5, A6, and
A7) the three high-voltage rectifier
boards (1293-1101), (A8, A19, A22, and
A23) filter capacitors, and (A16) the
choke that generate the high voltage.
The high-voltage power supply assembly
also contains the power supply metering
boards, the isolation relay boards, the
circuit breakers needed to supply high-
voltage metering, high voltage-on sense,
the power-on sequence, the switching on
and off, and the protection of the high
voltage. The high-voltage power supply,
at TB2, is connected to the 10-kW
assembly that provides the +12 VDC for
metering, switching, and the Enable to
the high-voltage power supply.
2.1.4 (A19) Visual/Aural Metering
Assembly (1162-1402; Appendix A)
The visual/aural metering assembly takes
the forward and reflected power samples
from the (A2-A2) and the (A18) output
couplers. The assembly provides the
metering control panel on the front panel
meters with visual, aural, and reflected
levels for remote monitoring and VSWR
protection.
The visual/aural metering assembly
consists of (A1) a single peak detector
board (1162-1403) for the reflected