5-22 888-2463-001 3/6/08
WARNING: Disconnect primary power prior to servicing.
Diamond Series™
Section 5 Maintenance and Alignments
5.6 Main Controller VSWR Foldback
This adjustment will set the association between reflected voltage from the RF detector
and the exciter foldback power for a CD-1A exciter only.
NOTE:
This procedure is not required for APEX exciters. For APEX exciters this fold-
back setting is set via software and adjustment is not required. For more informa-
tion see the APEX exciter manual.
a. Calibrate the system reflected power reading from the directional coupler follow-
ing the procedure "5.5.2 Reflected Power Calibration" on page 5-11.
b. On the Exciter AGC board, preset *R83, VSWR gain pot, fully CCW.
c. On the Main Controller board in the control rack, monitor TP4, Exc A.
d. Inject a DC voltage of 1.5 - 1.7 volts into the RF detector in the back of the con-
trol cabinet at TP2. You can use a 1.5 volt battery connected to the test point and
chassis ground.
e. The Main Controller TP4 voltage will increase to approximately 4.8Vdc, the top
rail of the circuit.
f. Adjust the Exciter *R83 foldback pot to show 30% of nominal output power on
the front of the Exciter.
g. Repeat this procedure for Exciter B in dual Exciter transmitters.
NOTE:
In older exciters, the foldback pot was labelled R10 on the AGC Board.
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