Keysight E8357D/67D & E8663D PSG User’s Guide 317
Troubleshooting
RF Output Power Problems
reverse power can cause amplitude modulation of 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 RF carrier of the
signal generator.
Reverse power problems can be solved by using one of two unleveled
operating modes: ALC off or power search.
Setting ALC Off Mode
ALC off mode deactivates the automatic leveling circuitry prior to the signal
generator’s RF output. In this mode, a power meter is required to measure the
output of the signal generator and assist in achieving the required output
power at the point of detection.
Use the following steps to set the signal generator to the ALC off mode:
1.
Preset the signal generator: press
Preset
.
2.
Set the desired frequency: press
Frequency
and enter the desired
frequency.
3.
Set the desired amplitude: press
Amplitude
and enter the desired
amplitude.
4.
Turn the RF on: set
RF On/Off
to On
5.
Turn the signal generator’s automatic leveling control (ALC) off: press
Amplitude
>
ALC Off On
to Off.
6.
Monitor the RF output amplitude as measured by the power meter.
Press
Amplitude
and adjust the signal generator’s RF output amplitude
until the desired power is measured by the power meter.
Poor Pulse Performance
For pulse widths <1 microsecond, you may need to do a power search to
optimize the pulse performance of the instrument. Refer to
Setting Power Search Mode
Power search mode executes a power search routine that temporarily closes
the ALC, calibrates the power of the current RF output, and then opens the
ALC circuitry. See the Keysight PSG Signal Generators Key Reference for more
information on the Power Search function.
CAUTION
There are two “RF During Power Search” settings available for the power
search, Minimum and Normal. The Minimum softkey sets the internal
attenuator to its maximum setting during power search to protect the power
sensitive circuits. When the power search has completed the attenuator is
returned to the last attenuator setting before the power search was executed.
The Normal softkey executes the power search without this added attenuator
protection.
