mended that the VSWR foldback threshold adjustments not be
changed from the factory settings, 1.20:1 visual and 1.40:1 aural.
NOTE
The following adjustments assume correct calibration of the for-
ward and reflected power metering.
5.22.2 Visual Foldback and Fault Adjustment
a. Depressand hold both exciterlowerbuttonsfor15 seconds
to insure minimum output
b. Temporarily remove the remote I/O cable from J9 on the
back of the exciter to enable the exciter without running
the transmitter.
c. Connect the visual exciter output for the visual forward
power sample at J6 on the back of the main controller.
d. Connect the aural exciter output to the visual transmitter
reflected power sample input J8 on the back of the main
controller, 1A3.
e. Adjust the visual exciter output for 100% power on the
front panel transmitter meter.
f. Set the level of the reflected signal (aural exciter) such that
the front panel display indicates a visual VSWR of 1.20:1.
g. If the front panel FOLDBACK ACTIVE fault indicator is
on, adjust the visual foldback threshold adjust (R20 on the
main controller) until the foldback indicator turns off.
h. Now adjust R20 until the FOLDBACK ACTIVE fault
indicator just comes on.
i. Set Visual foldback jumper J18 to connect pins 2 and 3
(disabled)
j. Slowly raise the aural exciter power. The VSWR FAULT
lamp should illuminate at approximately 1.4:1. R51 ad-
justs the threshold of the VSWR fault.
k. Lower the aural exciter power. Reinstall J18 to pins 1 and
2 (enabled).
5.22.3
Aural Foldback and Fault Adjustment
a. Connect theaural exciter output to theaural forward power
sample at J7 on the main controller.
b. Connect the visual exciter output to the aural transmitter
reflected power sample input J9.
c. Adjust the aural exciteroutput for100% poweron the front
panel transmitter meter.
d. Setthe level of the reflected signal (visual power) such that
the front panel display indicates a aural VSWR of 1.40:1.
e. If the front panel FOLDBACK ACTIVE fault indicator is
on, adjust the aural foldback threshold adjust (R33 on the
main controller) until the foldback indicator turns off.
f. Now adjust R33 until the FOLDBACK ACTIVE fault
indicator just comes on.
g. Set Aural foldback jumper J19 to connect pins 2 and 3
(disabled).
h. Slowly raise the aural exciter power. The VSWR FAULT
lamp should illuminate at approximately 1.6:1. R63 ad-
justs the threshold of the VSWR fault.
i. Lower the aural exciter power. Reinstall J19 to pins 1 and
2 (enabled).
j. Restore the normal inputsto the main controller J6through
J9. Reconnect P9 to the back of the exciter, this connection
is vital for VSWR protection.
5.23 Slave Controller RF Detectors
5.23.1 Slave Controller
The Slave Controller has 6 RF peak detectors for use in the
various system configurations. They are normally used to read
the visual drive power to the visual PA final amplifiers, but in
someconfigurationsare used toreadthe auralPAoutputsamples.
5.23.2
Visual Driver Calibration
To calibrate the visual drive, set the transmitter up for normal
operation using a black picture signal, and check for proper sync
level. Then, disconnect the coax drive line to the final PA splitter
and patch it into a 50 Ohm dummy load witha wattmeter. Finally,
set the Slave Controller peak detector calibration potentiometer
so that the display panel visual drive wattmeter peak of sync
power reading corresponds to the average power level read on
the patched-in wattmeter. (Multiply the wattmeter reading by
1.68 for M/NTSC systems, or 1.76 for systems B/PAL and
B/SECAM, to convert the average power measurement to a
peak-of-sync power figure.) Return the drive line coax cable to
the PA splitter input.
Section V - Maintenace
Rev. B: 1/11/1999 888-2365-001 5-13
WARNING: Disconnect primary power prior to servicing.
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