ALC Modulation Driver Bias

Use this calibration to optimally set the ALC MOD DRIVER BIAS/GAIN DAC and the ALC MOD OFFSET DAC on the output boards. The ALC MOD DRIVER BIAS/GAIN DAC primarily is used to accommodate unmatched VBE values in the drivers, but it has a strong influence on the modulator gain.

The goal of this calibration is to adjust the ALC MOD DRIVER BIAS/GAIN DAC until the ALC modulator gain is balanced about its nominal design center. Then the ALC MOD OFFSET DAC is adjusted until the gain of the modulator forces the loop integrator ABUS node to zero.

Required Test Equipment

Equipment: Required only if an output board is E4400-60659 or later.

Test Equipment

Recommended Model

Alternate Model

Power Meter

N1914B

N1914A1
N1913A
N1913B

E4418A
E4418B
E4419A
E4419B

Power Sensor

N8482A

E9304A
E9304A H18
N8482A CFT
8482A2

  1. Power meter N1914A with serial numbers ranging between MY00000000—MY53040007 require Service Note 07 to be applied for measurement repeatability. Please have this service note applied or verify it was applied before using this power meter. The affected service note is N1914A-07.

  2. Not allowed for the following product configurations:

    • E4438C with Option 506
    • E4428C with Option 506

    The dynamic frequency range of this sensor is insufficient for these models.

Connections and Setup Procedures
  • All test equipment requires a 30 minute warmup period to ensure accurate performance.
  • In the following adjustment setup, cables are designated as solid lines and direct connections are designated as dashed lines.
  1. Connect all test equipment as shown.
  2. Connect GPIB cables to all GPIB-controlled test equipment.
  3. While performing this adjustment, follow all instructions on the controller display.

 

If the signal generator displays a message indicating that the current power level accuracy calibration data is invalid, run the Power Flatness adjustment to correct the calibration data.

Power Meter Zero and Cal Setup

 

 

 

In Case of Difficulty

If this adjustment fails, perform the following steps in order:

  1. Check the equipment setup (see above). If the setup is incorrect, make the necessary corrections and rerun the adjustment.

  2. If this adjustment fails with the equipment set up properly, refer to the troubleshooting section of the signal generator's service guide. If you do not have a printed copy of the service guide (Option OBW), one is available either on the CD-ROM that came with your signal generator shipment or on the Keysight Website.

  3. If you cannot correct the problem using the troubleshooting procedures in the Service Guide, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.