Broadband Power Problems; Alc/Signal Separation Check - Agilent Technologies 8719ET Service Manual

Source Troubleshooting

Broadband Power Problems

Broadband Power Problems
This section assumes that a power problem exists across the full frequency range, and that
no error message is displayed. On ES models, the problem may affect PORT 1, PORT 2, or
both. On ET models, the problem may affect the REFLECTION port. Suspect assemblies
include:
A69 step attenuator
A74 transfer switch
A62 directional coupler
A55 YIG1
A54 YIG2 (8722ET/ES Only)

ALC/Signal Separation Check

1. Press
Sweep Setup
2. For ES Models:
Choose which port to begin troubleshooting by pressing the following:
Meas Refl: FWD S11 (A/R)
For ET Models:
Troubleshoot the REFLECTION port by pressing the following:
REFLECTION
Meas
1. To disable the ALC eliminate modulator control, press
SERVICE MODES
the power at the faulty port.
2. For 8719ET/ES and 8720ET/ES
If you measure at least +5 dBm (+10 dBm on ET models and ES Option 007 models)
at the port, replace the A59 source interface board assembly.
For ES Models Only
• If you measure less than +5 dBm (+10 dBm on Option 007 models) at the port, press
and
Refl: REV S22 (B/R)
Meas
the other port.
• If you measure less than +5 dBm (+10 dBm on Option 007 models) at the other port,
continue with "Step Attenuator (A69) Check"
• If you measure at least +5 dBm (+10 dBm on Option 007models) at the other port,
either the directional coupler or the bias tee or the transfer switch (A25) is faulty.
The power loss through each of these components should be negligible.
7-26
A59 source interface board
A58 M/A/D/S
A60 bias tee
A63 directional coupler
A74 switch splitter (Option 400 Only)
CW FREQ
3 G/n
for PORT1 or
SRC ADJUST MENU
or
Refl: FWD S11 (A/R)
A5 (source switch)
A61 bias tee
A6 (source switch)
A25 switch (8722ET/ES Only)
.
Refl: FWD S22 (B/R)
System
. Use a power meter to measure
ALC OFF
and measure power at
next.
8719ET/20ET/22ET
8719ES/20ES/22ES
RF Network Analyzers
for PORT 2
SERVICE MENU
Service Guide