FM Path Offset Calibration

(E8257D, E8267D, E8663D with Option UNT and E8257N Only)

This adjustment generates a DAC value to null the voltage offsets on the A6 Frac-N and A11 Pulse/Analog Modulation Generator.

During this adjustment, when FM is enabled the A6 Frac-N and A11 Pulse/Analog Modulation Generator may generate unwanted voltage offsets. These voltage offsets detune the Frac-N VCO from the desired frequency.

There are two FM Offset DACs, which generate a correction value for the external inputs: internal FM and FM internally grounded. The two external inputs can either be AC- or DC-coupled. With all these different combinations, a total of 13 correction values are generated and stored in FlashROM.

The adjustment algorithm uses a frequency counter to determine the Frac-N nominal frequency. The frequency counter is used to calculate the FM Offset DAC sensitivity (DAC counts/Hz). The correction DAC value is then calculated and stored in FlashROM.

Test Equipment

Preferred Model

Alternate Model(s)

Frequency Counter

53230A Opt 010 and (106 or 115)

53132A Opt 010 and (050 or 124)

 

Connections and Setup Procedures

  • With the exception of the 53132A Option 050 or 124, or the 53230A Option 106 or 115 frequency counter, all test equipment requires a 30 minute warmup period to ensure accurate performance.

  • The frequency counter must be plugged into the AC power line for at least 24 hours before testing begins.

  • In the following test 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.

 

Setup for FM Path Offset Calibration

 

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.