456 Keysight EXG and MXG X-Series Signal Generators User’s Guide
Troubleshooting
RF Output
Signal Loss While Working with a Spectrum Analyzer
The effects of reverse power can cause problems with the RF output when you use the signal
generator with a spectrum analyzer that does not have preselection. Use an unleveled operating
mode (described on page 121).
A spectrum analyzer can have as much as +5 dBm LO feedthrough at its RF input port at some
frequencies. If the frequency difference between the LO feedthrough and the RF carrier is less than
the ALC bandwidth, the LO’s reverse power can amplitude modulate the signal generator’s RF
output. The rate of the undesired AM equals the difference in frequency between the spectrum
analyzer’s LO feedthrough and the signal generator’s RF carrier.
Reverse power problems can be solved by using one of the unleveled operating modes.
See:
— “ALC Off Mode” on page 121
and
— “Power Search Mode” on page 122
To avoid damaging or degrading the performance of the signal generator,
do not exceed 33 dBm (2 W)
maximum of reverse power levels at the RF
input. See also
Tips for Preventing Signal Generator Damage on
www.keysight.com.