Data Sheet Chapter 5

4-6 kW UHF Translator Chapter 5, Detailed Alignment Procedures
837B, Rev. 0 5-18
5.9 Calibration of the Forward
Output Power Level of the Translator
Note: - Perform the following only if the
power calibration is suspect.
Switch the Translator to Standby and
preset R51, Aural Null pot, located on the
Visual/Aural Metering Board (1265-1309)
in the Metering Panel, full CCW. Adjust
R48, the Null Offset pot, located on the
Visual/Aural Metering Board, for 0%
Visual Output. Do the following
adjustments with no Aural present, by
removing the Jumper Cable W1, Aural IF
Loop-Thru, connected to J16, located on
the Sync Tip Clamp/Modulator Board
(1265-1302) in the selected UHF Exciter.
Connect a Sync and Black Test Signal to
the Video Input Jack J2 on the Remote
Interface Assembly of the UHF Exciter
Tray. Switch the Translator to Operate.
Next, set the Translator up for the
appropriate Average Output Power Level.
Peak of Sync Visual + Black 0 IRE Setup
equals; for 4 kW 2380 Watts, for 5 kW
2975 Watts and for 6 kW 3570 Watts.
Peak of Sync + Black 7.5 IRE Setup
equals; for 4 kW 2180 Watts, for 5 kW
2725 Watts and for 6 kW 3270 Watts.
NOTE: Must have 40 IRE Units of Sync.
Adjust R28, Visual Calibration, located on
(A10) the Visual/Aural Metering Board
(1265-1309) in the Metering Panel, for
100% on the front panel Combined Meter
in the % Visual Position.
With the Spectrum Analyzer set to Zero
Span Mode obtain a peak reference on
the screen. Reconnect the Jumper Cable
W1 to J16 located on (A5) the Sync Tip
Clamp/Modulator Board in the UHF
Exciter. While in the Combined Visual
Output Power position, adjust L3 for
minimum visual power reading. Turn the
power adjust pot on the front panel of
the Exciter until the original peak
reference level is attained. Switch to the
Combined Aural Output Power position
and peak L1 and C8 for maximum Aural
Power reading. Then adjust R20 also for
100% Aural Power reading. Switch to
Combined Visual Output Power position
and adjust R51 for 100% Visual Power.
5.10 Calibration of the Reflected
Output Level of the Translator
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
Translator, 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 Translator to Standby. Move
the cable on J5 to J6 and the Termination
on J6 back to J5. Switch the Translator
to Operate and adjust the front panel
power pot for 100% Visual Power reading
on the Combined Meter.
5.11 Calibration of the Reject Power
of the Translator
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.