Keysight NFA Series Noise Figure Analyzers Service Guide 151
RF Section Troubleshooting (N8973B, 74B, 75B Analyzers)
Troubleshooting
3. Front End Control Assembly Verification
Verifying the Front End Control Assembly requires the RF Front End
Troubleshooting board E4410-60115 or kit number N9020-60005. The kit
includes the troubleshooting board and associated interconnect cables. The
troubleshooting board and cables will help verify the control logic from this
assembly to Input Attenuator A, Input Attenuator B, Low Band Switch, YTF
Preselector, (Optional) Low Band Preamplifier, (Optional) High Band
Preamplifier, and the RF Front End Assembly. The control logic should be
verified going to each assembly while the Front End Troubleshooting board is
connected.
— Turn off the instrument.
— Connect the E4410-60115 Front End Troubleshooting board to the A15
Front End Control Assembly as shown in Figure 4-10 and Figure 4-11
Even though the YTF Preselector is not used in low band (input frequencies
< 3.59 GHz), it is easy to test the switch control logic with the RF Front End
Troubleshooting board installed in case there is a high band problem. The
Low Band Preamplifier (Option Pxx) and High Band Preamplifier logic
should be tested if these options are installed in the analyzer.
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