Unlocked Pll - Agilent Technologies 8564EC Service Manual

Figure 11-5 PLL Locked at Wrong Frequency

Unlocked PLL

An unlocked PLL can be caused by problems inside or outside the PLL.
Troubleshoot this problem by working backward from the oscillator as
described in the steps below. Numbers in the following text identify
items in
1. The loop integrator output voltage (1) should be attempting to tune
Chapter 11
Figure 11-6 on page
the oscillator to the correct frequency:
The voltage at (1) should increase as the frequency increases on
all of the PLLs:
General PLL Troubleshooting
536.
Synthesizer Section
535