Agilent Technologies E4440A, Service Manual

Page: 115 / 436

Chapter 5 115
Troubleshooting the Synthesizer Section
Verifying the A12 Synthesizer Board
Power on the PSA and immediately measure the Sampler out signal
amplitude on the spectrum analyzer. The signal should be 4 GHz at
0 dBm. If the PSA's internal auto align runs, the measured signal will
change to about -13 dBm. Therefore, perform the measurement during
the boot process.
Extend the A12 synthesizer using the E4440-60049 extender board. You
will need to install the special offset board guides so the extender card
will fit into the motherboard connector with out bending the extender
board. Also, connect an extender SMA cable between the sampler in
cable W24 and J1.
Measure the 600 MHz input by connecting the spectrum analyzer and
SMA cable to the extender board jack P2. Set the extender board switch
in the lower position. The signal should measure 600 MHz at -5 dBm.
Measure the 10 MHz input signal by connecting the spectrum analyzer
to P3 on the extender board. The 10 MHZ signal should measure
+2 dBm.
Determining which of the two sub assemblies is faulty
The PSA has two major phase lock modes, dual loop mode is used in
frequency spans < 2 MHz and single loop mode is used for frequency
spans
≥
2 MHz. These frequency breaks occur when the phase noise
optimization under the auto couple menu is set to auto. Troubleshooting
is performed by placing the PSA in each of the modes to determine
where the unlock condition occurs.