7-26 Service Guide
Source Troubleshooting 8719ET/20ET/22ET
Broadband Power Problems 8719ES/20ES/22ES
RF Network Analyzers
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:
ALC/Signal Separation Check
1. Press .
2. For ES Models:
Choose which port to begin troubleshooting by pressing the following:
for PORT1 or for PORT 2
For ET Models:
Troubleshoot the REFLECTION port by pressing the following:
1. To disable the ALC eliminate modulator control, press
. Use a power meter to measure
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 or and measure power at
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” next.
• 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.
A69 step attenuator A59 source interface board A5 (source switch)
A74 transfer switch A58 M/A/D/S A61 bias tee
A62 directional coupler A60 bias tee A6 (source switch)
A55 YIG1 A63 directional coupler A25 switch (8722ET/ES Only)
A54 YIG2 (8722ET/ES Only) A74 switch splitter (Option 400 Only)
3 G/n
Meas
Meas
System
Meas
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