HP (Hewlett-Packard) HP 85660B ユーザーズマニュアル

The fundamental RF signal input to the A6 RF Module (2 to 6.2 

 is generated by the

 YTO (YIG-Tuned Oscillator). This signal is phase-locked, through other phase-lock

loops, to the A22 10 MHz Standard (internal crystal oscillator). The YTO Loop pretunes and
locks the YTO signal to the output of the M/N Loop (part of A7) and the A10 

 Loop.

The M/N and 

 Loops serve two basic functions. First, they phase-lock the YTO Loop

to the 10 MHz Standard through the Reference Loop (part of A7). They also provide the
stepped tuning of the YTO output signal. The M/N Loop provides the larger steps (2000 to
6199 MHz in 10 MHz steps) while the 

 Loop provides the smaller (1 MHz to 1 Hz) steps.

All phase lock loops are referenced, either directly or indirectly, to the A22 10 MHz Standard.
Figure 1. shows the relationship between the various loops as well as defining the assemblies

associated with the loops.

I

Figure 1. Phase Lock Loops (Synthesizer), Block Diagram

Analog Troubleshooting 1