Source Low Band Operation - Agilent Technologies 8752C Service Manual

Source Low Band Operation

A signal (FN LO) is generated by the fractional-N VCO.
The fractional-N VCO signal is mixed with 40 MHz to produce a
reference signal.
The A3 source is pretuned. The source output is fed to the A4 R
sampler/mixer.
The signal from the source is fed back (1st IF) to the phase comparator.
A tuning signal (YO DRIVE) tunes the source and phase lock is achieved.
12-16 Theory of Operation