N9030B PXA Signal Analyzer Service Guide 183
RF Section Troubleshooting (Millimeter-Wave Analyzers)
Troubleshooting
Troubleshooting a Low Band Problem
Refer to the RF Lowband Path Block Diagram (Millimeter-Wave Analyzers) in
Chapter 13 and follow the instructions in the settings box. To enable the
internal 50 MHz, −25 dBm calibrator signal press Input/Output, RF Calibrator,
50 MHz.
The Low Band signal path (sometimes referred to as Band 0) is used for all
signals less than 3.6 GHz when the analyzer is used in normal operation. If the
stop frequency is set to 3.6 GHz, the analyzer displays only the Low Band
signal path. If the analyzer stop frequency is set above 3.6 GHz and the start
frequency is set below 3.6 GHz, the analyzer will sweep up to 3.6 GHz in low
band and then automatically switch to the high band path above 3.6 GHz.
A11 Low Band Switch Verification
Disconnect W8 from A13A1J2. See Figure 5-3 for location of connector. Attach
a right angle SMA adapter to W8 and measure the output of the Low Band
Switch with a spectrum analyzer. Expected signal is 50 MHz at −35.3 dBm
since the Low Band Switch and Option LNP SW3 have a few tenths of a dB
loss.
If the signal level is incorrect, remove A10 Input Attenuator B output cable and
measure the output power. Expected signal is 50 MHz at −35 dBm. See Figure
4-2 for location of attenuator. If the attenuator output signal is correct but the
Low Band output at W8 is incorrect, suspect the A11 Low Band Switch, the
interconnect cables, Switch 3 if Option LNP is present, or the control signals.
The control signals are explained in Chapter 6, “Front End Control
Troubleshooting”, on page 199.
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