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Chapter 12 247
Troubleshooting
No Modulation at the RF Output
4. Turn the RF off: set RF On/Off to Off
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.
7. Press
Amplitude and adjust the signal generator’s RF output amplitude until the desired power is
measured by the power meter.
Setting Power Search Mode
Power search mode executes a power search routine that temporarily activates the ALC, calibrates the
power of the current RF output, and then disconnects the ALC circuitry. See the E8257D/67D PSG
Signal Generators Key Reference for more information on the Power Search function.
Use the following steps to set the signal generator to manual fixed power search 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 signal generator’s automatic leveling control (ALC) off: press
Amplitude > ALC Off On to Off.
5. Turn the RF on: set RF On/Off to On.
6. Press
Do Power Search.
This executes the manual fixed power search routine, which is the default mode.
There are three power search modes: manual, automatic, and span.
When
Power Search is set to Manual, pressing Do Power Search executes the power search calibration
routine for the current RF frequency and amplitude. In this mode, if there is a change in RF
frequency or amplitude, you will need to press
Do Power Search again.
When
Power Search is set to Auto, the calibration routine is executed whenever the frequency or
amplitude of the RF output is changed.
When
Power Search is set to Span, pressing Do Power Search executes the power search calibration routine
over a selected range of frequencies at one time. The power search corrections are then stored and
used whenever the signal generator is tuned within the selected range of frequencies.
No Modulation at the RF Output
Check the MOD ON/OFF annunciator on the display. If it reads MOD OFF, press Mod On/Off to toggle the
modulation on.
Although you can set up and enable various modulations, the RF carrier is modulated only when you
have also set
Mod On/Off to On.
On the E8267D, for digital modulation, make sure that
I/Q Off On is set to On.