HP 8753E Service Manual page 410

Node 29
FN VU3 Tun (Al4 FN VCO tuning voltage)
Perform step Al4 and then press LMeas) ~~~~~~~';;~# (29) @J c-1
Observe the Al4 F'N VCO tuning voltage. If the Al3 and Al4 assemblies are
functioning correctly and the VCO is phase locked, the trace should look Iike
Figure 10-17. Any other waveform indicates that the FN VCO
locked. The vertical lines in the trace indicate the band crossings. (The counter
can also be enabled to count the VCO frequency in CW mode.)
1044 Service Key Menus and Error Messages
Figure 10-17. Analog Bus Node 29
is not phase