Installation guide

Troubleshooting
Troubleshooting Non-Harmonic Spurious
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Troubleshooting Non-Harmonic Spurious
There are many different groupings a spur can fall into. The grouping determines what assembly is most
likely generating the spur. Each data point in the service software test report indicates what type of spur is
tested. The procedure for troubleshooting spurs is to identify the grouping based on failing a performance
test, checking for loose or broken cables or castings, and replacing the assembly.
Table 1-41
Type of Spur Options Description
Mixing Spurs All These spurs are generated by the mixing products
of the RF and IF signals on the A13 Output. The
instrument is tuned to a frequency in the
Heterodyne-Band (≤ 250 MHz) to measure these
spurs.
The most likely cause is the A13 Output.
Power Supply Spurs All These spurs are generated by the power supply
switching at a 75 kHz rate.
The most likely cause is the A6 Power Supply.
Offset Reference Spurs All These spurs are generated by the 10 MHz frequency
reference on the A18 Reference.
The most likely cause is the A18 Reference.
RF and LO Feedthrough Spurs All When the signal generator is tuned to a
heterodyne band frequency (≤ 250 MHz), the RF
and LO signals feed through from the mixer on the
A13 Output and generate spurs on the RF output.
The most likely cause is the A13 Output
Frac-N Spurs All These spurs are generated by the Frac-N phase-lock
loop. They show up at a small offset from the
carrier, so they are checked at a 3 kHz offset.
The most likely cause is the
A16 Frac-N (Option UNJ or Option 506) or the
A17 Synthesizer (Option 501, 502, 503, 504).