User's Manual
2650 Watt VHF High Band Transmitter Chapter 2, System Description,
Maintenance and Remote Interface Connections
435B, Rev. 0 2-2
In the VHF amplifier tray, a forward
power sample and a reflected power
sample from the 3-way combiner board
are connected to the AGC Control Board
that peak-detects the samples and
connects them to the front panel meter
of the tray.
2.2 Control and Status
Control and status information for the
transmitter is provided by the meter and
LED indicators on the front panel of the
VHF exciter. The switches and LED
indicators are part of the (A17)
transmitter control board that is mounted
so that the switches and LEDs are
operated or viewed from the front panel
of the VHF exciter.
Switch S1 is an Operate/Standby switch
that controls the output of the
transmitter by providing the Enables
that, when the transmitter is in Operate,
are needed to turn on the switching
power supplies in the two VHF amplifier
trays. In Operate, the green LED DS2 is
on and in Standby the amber LED DS1 is
on. NOTE: If the transmitter does not
switch to Operate when S1 is switched to
Operate, check that a dummy jumper
plug, with a jumper between pins 21 and
22, is connected to jack J9 on (A12) the
A/V input and remoter interface
assembly. This jumper provides the
interlock needed for the transmitter to
operate. If the interlock is present, the
green LED DS5, on the transmitter
control board, should be lit.
Switch S2 is an Automatic/Manual switch
that controls the operation of the
transmitter using the presence of the
video input signal. When the switch is in
Automatic, the green LED DS3 is lit and,
if the video input signal to the
transmitter is lost, the transmitter will
automatically switch to Standby. When
the video input signal returns, the
transmitter will automatically switch back
to Operate. With the system in Manual,
the amber LED DS4 is lit and the
operation of the transmitter is controlled
by the front panel switches. During
normal operation of the transmitter,
switch S2 should be in the Auto position.
The front panel of the VHF exciter also
has LEDs that indicate a Video Fault
(Loss; red LED DS9) and VSWR Cutback
(amber LED DS7).