
8712ET/ES and 8714ET/ES Troubleshooting and Block Diagrams
RF Network Analyzers Category 3 Failures: Inaccurate (but reasonably functional) Measurements
Service Guide 4-35
Troubleshooting Trace Drift for ES Models.
To check the uncorrected performance of the analyzer, follow the steps below. Refer to
Figure 4-6 on page 4-24, Figure 4-7 on page 4-25, and Figure 4-8 on page 4-26 for part
designators.
Checking the Uncorrected Directivity of the PORT 1, PORT 2, and the R Couplers
1. Set the analyzer to the default condition by pressing .
2. To turn off calibrations, press
.
3. Leave PORT 1 open.
4. Press .
5. Attach a good load to PORT 1, preferably from a cal kit.
6. The directivity limits are −25 dB for a 50Ω analyzer and −15 dB for a 75Ω analyzer.
Compare the trace to the appropriate limit.
a. Replace the A coupler if any part of the trace is above the appropriate limit. Refer to
“Removing the Coupler” on page 3-15.
7. If the previous step has passed, leave the load connected to PORT 1 and look at the
display for the R detector. Press
.
8. Normalize the load response for use as a reference. Press
. (Pressing twice will update the reference trace.)
9. Remove the load from the PORT 1 connector. All of the trace should be between +5 dB
and −5 dB. If it is outside this range, the directivity of the R coupler is unacceptable.
Replace the R coupler from the receiver assembly (A5).
10.When the previous step has passed, continue with the next step.
11.Press .
12.Attach a good load to PORT 2, preferably from a cal kit.
13.The directivity limits are −25 dB for a 50Ω analyzer and −15 dB for a 75Ω analyzer.
Compare the trace to the appropriate limit.
a. Replace the B coupler if any part of the trace is above the appropriate. Refer to
“Removing the Coupler” on page 3-15.
14.If the previous checks pass, leave the S22 trace displayed, press
and go to “Checking the Switch Terminations.”
PRESET
POWER 0
SYSTEM OPTIONS
MEAS 1
CAL
MEAS 1
CAL
MEAS 1
CAL
CAL
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