User's Manual

Digital UHF Transmitter Chapter 5, Detailed Alignment Procedures
DT835A, Rev. 1 5-13
measurement instrument), adjust the
output power for a reading of 2000, 2500
or 3000 watts on the true average power
meter. Adjust R28 on (A10) the
visual/aural metering board in the
metering panel for 100% in the %
Combined Output Power position. Set pot
R20 on (A10) the visual/aural metering
board full CCW.
5.9 Calibration of the Reflected
Output Level of the Transmitter
Turn the Power Adjust Pot on the UHF
Exciter to 20% on the Metering Panel
Combined Meter in the Visual Power
position. NOTE: Check that the Jumper
is in Manual on the UHF Upconverter
Board (1265-1310) in the UHF Exciter.
On (A11) the Output Coupler for the
Transmitter, move the cable on J6 to J5
and the Termination on J5 to J6. Adjust
R10 on the (A7) Dual Peak Detector
Board (1159965), in the Metering Panel,
for a 20% reading in the Combined
Reflected Power position. At this 20%
Reference Power reading, the VSWR LED
mounted on the front panel of the UHF
Exciter should be illuminated. If not
adjust R19 on the Detector Threshold
Board, in the Metering Control Panel,
until the VSWR LED just turns On. Turn
the Power Adjust pot slightly CCW and
the LED should go out, turn the pot CW
until the LED just turns On. The
Reflected Output Power is now calibrated.
Switch the Transmitter to Standby. Move
the cable on J5 to J6 and the Termination
on J6 back to J5. Switch the Transmitter
to Operate and adjust the front panel
power pot for 100% Power reading on
the Combined Meter.
5.10 Calibration of the Reject Power
of the Transmitter
Check that the System is operating at
100% Output Power. Remove the AC
power to the Side A Amplifier Array by
switching Off CB1 the Main AC circuit
breaker, located on the AC Distribution
Panel for the Side A Amplifier Array.
Adjust R9 on the (A7) Dual Peak Detector
Board, located in the Metering Control
Panel, for a 25% Power reading in the
reject power position. The Reject power
is now calibrated.
Return CB1, the Main AC circuit breaker
for the Side A Amplifier Array, to the On
position.
The Transmitter is fully aligned and
ready for normal operation