178 Keysight NFA Series Noise Figure Analyzers Service Guide
RF Section Troubleshooting (N8973B, 74B, 75B Analyzers)
Troubleshooting
3. Front End Control Assembly Verification
IMPORTANT If the Front End Control Assembly logic was verified in the 'Low Band Quick
Check' section above, skip to “Input Attenuator A Power Level Verification”
step below.
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, Low Band Preamplifier, 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 4-27 and Figure 4-28.
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