8-4 Service Guide
Receiver Troubleshooting 8719ET/20ET/22ET
At Least One Signal Path Looks Normal 8719ES/20ES/22ES
RF Network Analyzers
At Least One Signal Path Looks Normal
One normal signal path indicates that at least one sampler, one 2nd converter, A12, and
much of A10 are functional. Therefore, substitution is a convenient troubleshooting
approach. If two signal paths are abnormal, repeat the steps of this section for each
suspect signal path.
1. To see the traces of signal path A or R, connect a short to PORT 1 on ES models
(REFLECTION port on ET models).
Press the following:
, or
2. To see the traces of signal path B or R2 (if the instrument is an ES model Option 400),
connect a short to PORT 2 on ES models. On ET models, connect an RF cable to the
REFLECTION and TRANSMISSION ports. Then press the following:
or
( on ES models) ( on ET models)
3. For examples of the normal signal traces, refer to Figure 8-1 on page 8-6. For signal
trace nominal power levels, refer to Table 8-2 on page 8-5.
NOTE The illustrations depicting the analyzer display were made using an 8722ES
model with nominal test port power. Other analyzer displays may appear
different, depending on model and options.
• Even if the R signal path trace is abnormal, the R sampler is nonetheless good (or
there would be a phase lock problem). Go directly to “2nd Converter Check” on
page 8-9.
• If the A or B signal path is very low and the R signal path is normal, go to “A and B
Sampler Check by Substitution” on page 8-8.
• If the A or B signal path appears slightly low, the problem is possibly a faulty
directional coupler or, more probably, a lossy sampler. To isolate the fault, continue
with “Directional Coupler Check” on page 8-7.
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