User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD Appendix A: System &
ATSC Transmitter/Regenerative Translator Drawers Drawings and Parts List
Instruction Manual, Rev. 0 A-3
Figure 16A: (A5) ALC Board (1308570)
Refer to Figure 16A. Turn the output power down to 10% power with R62 on the ALC
Board. Remove the output RF connector from J2 on drawer and calibrate the reflected
power to 10%, using R7, the Reflected Calibration pot, on the Output Detector Board.
Refer to Figure 17. Re-connect the RF output connector to the drawer and increase the
power, in Manual gain using R62 on the ALC Board, to 115%. Adjust the Overdrive pot
R38 on the ALC Board, CCW until the overdrive threshold just trips and the Overdrive
Fault LED DS4 lights. Turn R38 slightly CW so that power comes back up and DS4 goes
out.
Switch S1 on the ALC Board to ALC. Turn the ALC Adjust pot R75 on the ALC Board until
the power is 100%. Switch S1 between ALC and Manual to verify smooth switching, with
minimal change in power. If necessary repeat the above procedure.
With the drawer in ALC, use the ALC Adjust pot, R75, to decrease the power to 10%.
Remove the RF output connector from the drawer. Verify that the VSWR Cutback LED,
DS6, comes on and the Reflected Power drops to approximately 6%. Reconnect the RF
output connector and increase the power back up to 100% using R75.
This completes the set up of the ALC board and the Forward and Reflected Power
Calibration.
Forward and Reflected Power Calibration of a CU1TD/RD-1 and Higher Power
Systems with one or more External Amplifier Drawers
NOTE: If your system is a CU0TD/RD-1 thru CU0TD/RD-5, refer to the previous section
for the forward and reflected power calibration procedures.
Connect a calibrated coupler and average reading power meter to the output of the DTV
mask filter. On the ALC Board (1308570), mounted in the Driver Drawer, set the Switch
S1, Auto/Manual ALC, to the Manual position. Refer to Figure 13A.
Adjust the Manual adjustment Pot, R62, for the desired output power level as indicated on
the average reading power meter. In the Amplifier Drawer, on the Amplifier Control Board
(1309822), refer to Figure 18; adjust the Forward Calibration Adjustment pot, R8, for a
R38
OVERDRIVE
THRESHOLD
S1
AUTO/MAN
R75
ALC ADJ
R62
MAN ADJ
J4