9-4 Service Guide
Accessories Troubleshooting 8719ET/20ET/22ET
Inspect the Error Terms 8719ES/20ES/22ES
RF Network Analyzers
Inspect the Error Terms
Error terms are a measure of a “system”: a network analyzer, calibration kit, and any
cables used. As required, refer to Chapter 11 , “Error Terms,” for the following:
• The specific measurement calibration procedure used to generate the error terms.
• The routines required to extract error terms from the instrument.
• Typical error term data.
Use Table 9-1 to cross-reference error term data to system faults.
If you detect problems using error term analysis, use the following approach to isolate the
fault:
1. Check the cable by examining the load match and transmission tracking terms. If those
terms are incorrect, go to “Verify the RF Cable” on page 9-6.
2. Verify the calibration kit devices:
• Loads: If the directivity error term looks good, the load and the test port are good.
On ES models, if directivity looks bad, connect the same load on the other test port
and measure its directivity. If the second port looks bad, as if the problem had shifted
with the load, replace the load. If the second port looks good, as if the load had not
been the problem, troubleshoot the first port.
Table 9-1 Components Related to Specific Error Terms
Component Directivity Source
Match
Reflection
Tracking
Isolation
(Crosstalk)
Load
Match
Transmission
Tracking
Calibration Kit
load X X
open/short X X X
Analyzer
coupler X XXXXX
bias tee XXXXX
transfer switch X X X X X
step attenuator X X X X
sampler X
X
*
X
A10 digital IF X
test port
connectors
X XXXXX
External cables XX
* This component is likely to contribute to crosstalk at 4 GHz.
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