Data Sheet Chapter 5

4-6 kW UHF Translator Chapter 5, Detailed Alignment Procedures
837B, Rev. 0 5-10
input terminals of the tray at
TB1-1 (+), TB1-2 (-), and TB1-
3 (ground) on the rear chassis.
B. Connect the combined IF
output at J21, the IF sample on
the clamp modulator board, to
the input of an IF splitter.
Connect one output of the
splitter to the video
demodulator and the other
output to the spectrum
analyzer.
C. Connect a short cable at the
front of the demodulator from
the RF-out jack to the IF-in
jack.
D. Connect a cable from the 600-
Ω audio output jack of the
demodulator to the input of an
audio distortion analyzer.
2. Set the output frequency of the
audio oscillator to 400 Hz and the
output level to +10 dBm.
3. Center the aural carrier on the
spectrum analyzer with the
spectrum analyzer set to the
following:
• Frequency/Division: 10 kHz
• Resolution Bandwidth: 3 kHz
• Time/Division: 50 msec
• Trigger: Free run
A. Adjust L5 for approximately
+3.5 VDC at TP2.
B. The green LED DS1 should be
illuminated, indicating a locked
condition. If not, retune L5 for
a locked condition.
4. Adjust R13, balanced audio gain, on
the aural IF synthesizer board for
±25 kHz deviation.
5. Check the distortion on the aural
distortion analyzer (< 0.5%).
6. Disconnect the 600-Ω balanced
audio input to the tray. Connect a
75-Ω stereo audio input (400 Hz at
1 Vpk-pk) to composite audio input
jack J3 on the rear of the tray.
Follow the procedure in the stereo
generator instruction manual for
matching the level of the generator
to the exciter. R17 is used to adjust
the composite audio gain.
7. Check the distortion level on the
distortion analyzer (< 0.5%).
5.3.7 (A8) ALC Board (1265-1305;
Appendix D) (Part 1 of 2)
The following details the meaning of each
LED of (A8) the ALC board when it is
illuminated:
• DS1 - Red LED: Indicates that an
abnormally low IF signal level is
present at IF input connector J1
• DS2 - Red LED: Indicates that the
ALC circuit is unable to maintain the
signal level requested by the ALC
reference; this is usually due to
excessive attenuation in the linearity
or the IF phase corrector signal path,
or because the jumper W3 on J6 is in
manual gain
• DS3 - Red LED: Indicates a video loss
fault
• DS4 - Red LED: Indicates that a Mute
command is present (not used in this
configuration)
• DS5 - Green LED: Indicates that the
output from the modulator is selected
as the input to the ALC board
1. To align the ALC board, preset the
following controls in the UHF exciter
tray:
• ALC board – Move jumper W1 on J4
to disable, between pins 2 and 3 (to
disable linearity correctors); move
jumper W3 on J6 to manual, between
pins 2 and 3 (for manual gain