System Description Chapter 2

10-kW UHF Transmitter with Chapter 2, System Description
Feedforward Driver
840A, Rev. 0 2-10
SWITCH FUNCTION
turn-on sequence with the operator using
the front panel controls or remote
control.
HV (High Voltage) (S7)
Enable/Disable
When the switch is enabled (Up), the
magnetic latching relay (K1) on (A1) the
control logic board will engage. The high-
voltage enable indicator will light along with
the High-Voltage Request LED. The High-
Voltage On command to the high-voltage
relay will be applied at the proper time
during the automatic turn-on sequence.
When switched to Disable, the High-Voltage
On command will be removed, disabling the
high voltage and causing the Automatic Off
Cycle sequence to occur.
Output Power (S8)
Adjusts the output power level of the
transmitter by raising or lowering the ALC
level on the visual ALC/AGC board in the
UHF exciter tray. This control is used to
compensate for the small, everyday
variations in the output power level. If a
major variation occurs, a problem exists.
After the problem has been repaired, the
output power level adjustment may also
require a readjustment to the AGC
voltage levels (refer to the system setup
procedures in Chapter 3 of this manual).
Fault Reset (S9)
As a fault occurs in the transmitter, the
Fault LED will flash on and then go off as
the transmitter automatically resets itself
to try to eliminate the problem. If the
problem remains, the transmitter will try to
reset itself three times in approximately one
minute. After this, the Three-Fault indicator
will remain lit and the transmitter will
automatically shut down. When the problem
that caused the fault is found and repaired,
the Fault Reset switch S9 must be set
before the transmitter will recycle.
Driver Mode (S10)
Normal/Test
When the switch is in Normal (Up), the
transmitter operates normally. When the
switch is in Test (Down), the magnetic
latching relay (K4) on (A7) the transmitter
control board supplies the driver Enable to
the exciter/driver assembly. This allows the
operation of the exciter/driver assembly
without requiring the 10-kW amplifier
section to be on. When this function is
being performed, the driver must be
terminated into a dummy load and the high
voltage must be disabled.