TROUBLESHOOTING AND REPAIR
FREQUENCY SYNTHESIS
PROCEDURE:
The Lower Clamp frequency is adjusted to 15 MHz with the reference to the phase
detector disabled.
1. Connect output (J4) of the Sub-Synthesizer VCO (A3) to the frequency counter.
Set the frequency counter to measure with 1-kHz resolution.
2. Program the UUT to SPCL 909.
3. Program the UUT to 800 MHz. Frequency counter should read 16.000 MHz.
4. Short TP22 to ground.
5. Adjust R99 so that the frequency counter reads 15.000 MHz ± 10 kHz.
Upper Clamp Adjustment, R98 6C-8.
TEST EQUIPMENT:
• Frequency counter
REMARKS:
The Upper Clamp Adjustment, R98 is normally required only when U35, U36 or
associated components have been replaced, when the Sub-Synthesizer VCO (A3) has
been repaired or replaced, or when the adjustment has shifted.
PROCEDURE:
The Upper Clamp frequency is adjusted to 32.5 MHz with the N-divider signal to the
phase detector disabled.
1. Connect output (J4) of the Sub-Synthesizer VCO (A3) to the frequency counter.
Set the frequency counter to measure with 1-kHz resolution.
2. Program the UUT to SPCL 909.
3. Program the UUT to 640 MHz. Frequency counter should read 32.000 MHz.
4. Short TP21 to ground.
5. Adjust R98 so that the frequency counter reads 32.500 MHz ± 10 kHz.
SSB Mixer LO Drive Adjustment, R106 6C-9.
TEST EQUIPMENT:
• RF Probe (10X)
• Spectrum analyzer
REMARKS:
The SSB Mixer LO Drive Adjustment (R106) is normally required only when U50,
U51 or associated components have been replaced, when the Sub-Synthesizer VCO
(A3) has been repaired or replaced, or when the adjustment has shifted.
6C-14
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