244                                                                                   Keysight NFA Series Noise Figure Analyzers Service Guide
Front End Control Troubleshooting
A15 Front End Control Assembly Troubleshooting
Disconnect RF Front End Troubleshooting Board
You do not need the RF front end troubleshooting board to test out the 
remaining front end hardware components. At this point it is advisable to 
shutdown the analyzer and disconnect the test board and cables. Be sure to 
reconnect the Low Band switch ribbon cable and the input attenuator ribbon 
that were originally plugged into the Front End Control board before testing the 
input attenuator and low band switch logic.