HP 8753E - Page 324

Low Band REF Signal. In low band this signal follows the frequency of the RF
output signal. Figure 7-10 illustrates a 5 MHz CW signal.
sg612s
Figure 7-10. REF Signal at AllTP9 (5 MHz CW)
q If REF looks good, skip ahead to “4 MHz Reference Signal”.
q If REF is bad in low band, continue with TN Lo at Al2 Check”.
7-18 Source Troubleshooting