Troubleshooting Unlevels - Keysight N5171B EXG Service Manual

Troubleshooting

Troubleshooting Unlevels

Troubleshooting Unlevels
An Automatic Leveling Control (ALC) loop on the A3 RF assembly provides
leveled output power. The ALC loop is a feedback control system that monitors
RF power and maintains power at the user-selected level. The RF path must
provide a minimum power level to the ALC loop for the ALC loop to work
correctly. The minimum required power is slightly higher than the instrument
maximum power level.
A leveled output power is obtained by comparing a detected voltage with a
reference voltage. The detected voltage is generated by coupling off a portion
of the RF output signal and converting it to a dc voltage using detector diodes.
The reference voltage is generated using calibrated DAC's. When the reference
and detected levels are not the same, the ALC integrator output ramps up or
down, to increase or decrease the detected level. If the integrator cannot
achieve a match between the detected and reference voltages an unleveled
annunciator is displayed.
1. Run a complete self test.
2. Troubleshoot any unlocks.
3. Measure the output power at the RF connector.
4. Check the measured output power level against the values in
The output power values shown in these tables might not apply to your specific signal generator
configuration. Refer to the current data sheet for the latest power level data.
Keysight X-Series Signal Generators Service Guide
Press: Utility > Instrument Info > Sel f Test > Run Complete Sel f Test.
Refer to "Troubleshooting Unlocks" on page
Table 1-3
Frequency
N5171B/72B
9 kHz to 10 MHz
10 MHz to 3 GHz
3 GHz to 6 GHz
N5181B/82B
9 kHz to 10 MHz
10 MHz to 3 GHz
3 GHz to 5 GHz
5 GHz to 6 GHz
78.
Maximum Output Power
Standard
+13 dBm
+18 dBm
+16 dBm
+13 dBm
+18 dBm
+16 dBm
+16 dBm
Table 1-3.
Option 1EA
+17 dBm
+21 dBm
+18 dBm
+17 dBm
+24 dBm
+19 dBm
+18 dBm
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