Plref Waveforms - HP 8753E Service Manual

REF is the buffered PLREF+ signal. The 1st IF is
phase locked to this signal. Use an oscilloscope to observe the signal at the
frequencies noted in Figure 7-9 and Figure 7-10.
In high band the REF signal is a constant 1 MHz square
High Band Signal.
wave as indicated by Figure 7-9.
Figure 7-9. High Band REF Signal (216 MHz CW)
Source Troubleshooting 7-17