Troubleshooting Pulse Modulation - Keysight Technologies E8257D Service Manual

Troubleshooting
Troubleshooting the RF Path
6. To measure the A6 Frac–N output level, with the signal generator on,
Always turn the signal generator off before installing any assembly.
7. If power levels look good through the path in ALC Off mode, the problem is

Troubleshooting Pulse Modulation

1. Verify a license key has been entered for either Option UNU or UNW.
2. Run a full self–test and troubleshoot any reported failures before
3. Determine the frequency of the pulse modulation problem.
4. Configure the signal generator to the pulse modulation setting that
5. Connect an oscilloscope to the LF OUTPUT connector. The waveform
6. If the waveform is present, continue to step 7.
7. If the waveform is not present or the signal is not the correct amplitude or
8. Turn ALC Off. In ALC On mode, the ALC bandwidth limits pulse amplitudes
Troubleshooting Problems <3.2 GHz
9. If the pulse modulation problem occurs at <3.2 GHz, check P52–23 on the
Table 1-22
Pulse On
+5 Vdc
10.If signal levels are good, replace the A8 Output.
11.If the signals are bad, check the cable continuity. If the cable is bad,
124
remove the A8 Output and probe the right hand mmx connector's center
pin. The power level should be ≥+5 dBm.
most likely in the ALC loop. Go to troubleshooting the ALC loop.
proceeding.
produces the problem.
should be present on the oscilloscope.
type, replace the A11 Pulse/Analog Modulation Generator.
at pulse widths <1μs. If turning ALC Off corrects the problem, then verify
that pulse modulation is setup in either ALC Off or Power Search Modes.
A31 Motherboard. Compare the results with
Pulse Off
0 to +5 Vdc (pulses at modulation rate)
replace the cable. If the cable is good replace the A11 Pulse/Analog
Modulation Generator.
E8257D/67D, E8663D PSG Signal Generators Service Guide
Table 1-22.