140 Keysight CXG, EXG, and MXG X-Series Signal Generators Service Guide
Troubleshooting
Unleveled Issues
— If the DC voltage does not measure at least +10V proceed to
step 14.
12.Adjust the power level of the signal generator to -20 dBm by pressing
AMPTD, -20 dBm.
13.Verify that the DC voltage measured at the output of W23 measures -8V
or less:
— If the DC voltage measures -8V or less replace the A3 RF assembly.
— If the DC voltage does not measure -8V or less proceed to step 14.
14.Referring to Figure 6-2, reconnect W20 to A3 J2002 and W23 to A3
J6000.
15.Connect the spectrum analyzer to the signal generator RF output.
16.Adjust the power level of the signal generator to 0 dBm by pressing
AMPTD, 0 dBm.
17.Referring to Figure 6-2, remove W22 from both A3 J7 and A7A1 J11.
18.Remove W31 from A7A1 J10 and reconnect it to A7A1 J11.
— If the unlevel condition is now gone replace the A3 RF assembly.
— If the unlevel condition continues replace the A7 Micro-Deck
assembly.
2.0 GHz to <3.2GHz
In this frequency range the ALC modulators are located on the A3 RF assembly,
while the detector, ALC reference DAC, integrator, and summing amplifier are
all located on the A7 Micro-Deck assembly. Use the following procedure to
isolate an internal ALC unlevel condition in this frequency range:
1. Return the instrument to a known state by pressing Preset.
2. Tune the signal generator to 3 GHz by pressing FREQ, 3 GHz.
3. Turn the RF on by pressing RF On/Off so that the LED below it comes on.
4. Set the power level to +10 dBm by pressing AMPTD, 10 dBm.
5. Turn the attenuator hold on and by pressing AMPTD, Atten/ALC Control,
Atten Hold On.
When removing cables from the instrument when it is powered on exercise
caution as to not touch the shielding to any of the components or traces
on the assemblies.
Due to the differences in the detector characteristics the signal level seen
on the spectrum analyzer screen at this time, even with the ALC leveled,
may not be as accurate as it would normally be.
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