TROUBLESHOOTING AND REPAIR
RF LEVEL/AM
Output PCA Het Level Adjustment, R10 6D-19.
TEST EQUIPMENT:
• Power meter
• Power sensor (High-Level)
REMARKS:
The UUT must be operated at room temperature for at least one hour with the module
plate covers in place before continuing with this adjustment procedure.
This adjustment is normally required only when components in the het band circuits
have been replaced. It is also necessary to make this adjustment if R72 is adjusted.
CAUTION
This adjustment directly affects the output level and should not be made
indiscriminately.
PROCEDURE:
With the UUT programmed to +9 dBm, adjust the het level adjustment, R10, for equal
output power at 14.9 and 15 MHz.
1. Program the UUT to SPCL 01, 15 MHz, and +9 dBm.
2. Zero the power meter.
3. Remove the het level adjustment access screw from the bottom module plate cover.
4. Connect the Power Sensor to the UUT RF OUTPUT connector. Note the power
meter reading.
5. Program the UUT to 14.9 MHz.
6. Adjust the het level adjustment, R10, for a reading equal to that previously noted.
7. Reinstall the het level adjustment access screw.
Premodulator PCA Bandwidth Adjustment, R51 and C7 6D-20.
The following procedure covers the adjustment of R51 and C7 on the Premodulator
PCA. This adjustment optimizes the AM bandwidth in the 256 to 1056-MHz band.
TEST EQUIPMENT:
• Power meter
• Tuning tool, .025 in. sq., Johanson #4192
REMARKS:
This adjustment is normally made only if changes are made to the Premodulator PCA.
6D-17
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