242 Keysight NFA Series Noise Figure Analyzers Service Guide
Front End Control Troubleshooting
A15 Front End Control Assembly Troubleshooting
Input Attenuator B Control Logic Verification (N8976B)
Press MODE/MEAS, Spectrum Analyzer, OK, AMPTD, Attenuation, Mech
Atten, 10 dB on the analyzer and verify that the 10 dB Step LED DS18 is
illuminated.
If the LEDs illuminate correctly, the switch control logic for the input
attenuators from the A15 Front End Control assembly is correct. If the LEDs are
not illuminating as expected, the most probable cause is the A15 Front End
Control Assembly.
Set the input attenuator back to 10 dB by pressing AMPTD, Attenuation, Mech
Atten, 10 dB on the analyzer.
Table 6-7 Input Attenuator B LED’s (N8976B)
Attenuator Setting
(dB)
DS17 DS18 DS19
10 OFF ON OFF
20 OFF OFF ON
30 ON OFF OFF
40 ON ON OFF
50 ON OFF ON
60 ON ON ON