Agilent Technologies 8719ET - Check Fractional-N Digital (A14) with ABUS

7-14 Service Guide
Source Troubleshooting 8719ET/20ET/22ET
Broadband Phase Lock Problems 8719ES/20ES/22ES
RF Network Analyzers
Check Fractional-N Digital (A14) with ABUS
1. To setup the fractional-N tuning voltage, press the following:
Compare the fractional-N tuning voltage to Figure 7-2.
Figure 7-2 Fractional-N Tuning Voltage Waveform at Abus Node 21
2. Press and set the instrument to the
frequencies of column one in Table 7-1.
• If the voltage waveform resembles Figure 7-2 on page 7-14, but the counter values do
not match Table 7-1, A14 is the most probable fault.
Table 7-1 VCO Range Check Frequencies
Front Panel Displayed Counter Value
50 MHz 119.988 to 120.012 MHz
109.999 MHz 239.975 to 240.024 MHz
Preset
PRESET: FACTORY
Preset
Sweep Setup
SWEEP TYPE MENU
LOG FREQ
System
SERVICE MENU
ANALOG BUS ON
Meas
ANALOG IN Aux Input
COUNTER: ANALOG BUS
Format
LOG MAG
21 x1 Scale Ref
AUTO SCALE
COUNTER:FRAC N
Sweep Setup
CW FREQ