Chapter 7 7-17
Source Troubleshooting
Phase Lock Error
2ND LO Waveforms
The 2nd LO signals appear different in phase and shape at different frequencies.
90 Degree Phase Offset of 2nd LO Signals in High Band In high band, the 2nd LO
is 996 kHz. As indicated by Figure 7-13, the 2nd LO actually consists of two signals 90
degrees out of phase.
Figure 7-13 90 Degree Phase Offset of High Band 2nd LO Signals (≥16 MHz CW)
In-Phase 2nd LO Signals in Low Band The 2nd LO signals in low band, as shown in
Figure 7-14, are not phase shifted. In low band these signals track the RF output with a
4 kHz offset.
Figure 7-14 In-Phase Low Band 2nd LO Signals (14 MHz CW)
If any of the signals of Table 7-2 are incorrect, the probability is 90% that the A12
assembly is faulty. Either consider the A12 assembly faulty or perform the “A12 Digital
Control Signals Check,” described next.
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