FM Path Offset

When FM is enabled, voltage offsets on the reference and synthesizer boards appear as frequency shifts on the synthesizer VCO. This adjustment generates a DAC value to null the offsets associated with the various FM1 and FM2 paths on the reference board. 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.

This adjustment algorithm uses a frequency counter to measure the frequency shifts of the VCO. 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.

Required Test Equipment

Test Equipment

Recommended Model

Alternate Model

Frequency Counter

53230A Opt [106 or 115]

53132A Opt 010 and [050 or 124]
53131A Opt 010 and [050 or 124]

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.

 

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.