TROUBLESHOOTING AND REPAIR
RF LEVEL/AM
Mod Control PCA External Modulation Level Indicator Adjustment, R71 6D-16.
TEST EQUIPMENT:
•
DVM
REMARKS:
This adjustment is normally made if CR12 or R70-R74 are replaced.
PROCEDURE:
The potentiometer is adjusted to provide 0.98V DC at TP1. This adjusts both AM and
FM indicators, as the remaining levels are set by fixed resistors.
1. Remove the bottom instrument cover and remove the access screws for TP1 and
R71.
2. Connect the DVM to TP1 and ground.
3. Set the UUT to SPCL 01 and observe the DVM.
4. Adjust R71 for 0.980 volts.
5. Reinstall the access screws and bottom cover.
Mod Control PCA Sum Steer Gain Adjustment, R99 6D-17.
TEST EQUIPMENT:
•
DVM
REMARKS:
The Sum Steer Gain Adjustment is normally required only when U32, U36, or any
associated components are replaced.
PROCEDURE:
The sum steer voltage is adjusted to 10.24V with the Sum Loop VCO steering DAC set
to full scale.
1. Program the UUT to SPCL 01.
2. Program the UUT to SPCL 942. This Special Function programs all DACs to full
scale.
3. Connect the DVM to measure the voltage between J2 pin 14 and module ground.
4. Adjust R99 for 10.24V ± .01V.
5. Program the UUT for SPCL 00. This clears all Special Functions.
6D-15
To Next Page
Loading...
