User's Manual

300-Watt Digital UHF Transmitter Chapter 2, System Description
DT830A, Rev. 1 2-5
METER FUNCTION
% Exciter
(0-120)
Reads the % Exciter Output Power level
needed to attain 100% output of the
transmitter on the top scale
% Output power
(0-120)
Reads the % Output Power of the
transmitter on the top scale
% Reflected
(0-120)
Reads the % Reflected Output Power, <5%,
on the top scale
Table 2-7. UHF Exciter Tray Controls
SWITCH FUNCTION
Transmitter (S1)
Operate/Standby
The momentary switch (S1) applies a
ground to K1, a latching relay on
the transmitter control board. K1 will switch
either to Operate or to Standby
depending on which direction S1 is pushed.
When switched to Operate, the low Enable
commands are applied to the two or four
600-watt amplifier trays. These Enables will
turn on the 600-watt amplifier trays. The
opposite occurs when the transmitter is
switched to Standby.
Mode Select (S2)
Auto/Manual
The momentary contact switch (S2) applies
a ground to K2, a latching relay on the
transmitter control board. K2 will switch the
transmitter to Automatic or Manual
depending on which direction S2 is pushed.
In Automatic, the Video Fault command
from the ALC board will control the
operation of the transmitter. The
transmitter will switch to Standby, after a
slight delay, if the input video is lost. It will
quickly switch back to Operate when the
video is restored. In Manual, the transmitter
is controlled by the operator using the front
panel Operate/Standby switch or by remote
control.
Power adjust (R1)
Pot A20 sets the ALC level on the ALC
board to set the output power of
the transmitter.
Table 2-8. UHF Exciter Tray Fault Indicators
INDICATOR FUNCTION
VSWR cutback (DS7 amber)
Indicates that the reflected power level of the
transmitter has increased above 20% which will
automatically cut back the output power level to
20%. The fault is generated on the transmitter
control board in the UHF exciter tray.