DC FM Calibration

(E8267D, E8663D with Option UNT and without Option UNY, and E8257D with Option UNT and without Option UNY and without Option HNY, and E8257N Only)

This adjustment generates a correction voltage that is used to null any voltage offsets that are created by the A6 Frac-N and A11 Pulse/Analog Modulation Generator when FM is enabled. Without this adjustment, small voltage offsets may be generated that detune the Frac-N VCO from the desired frequency.

During this adjustment, the instrument is set for a 1 GHz carrier at 0 dBm. Internal FM is turned on with the EXT1 FM input left open. The FM Deviation is set for 1 MHz and the FM1 path is selected with DC-coupling. The instrument performs an internal calibration, which generates a frequency-offset value. This value is loaded into a register in an Application Specific Integrated Circuit (ASIC) on the A6 Frac-N.

A frequency counter is used to verify the corrected frequency is within +/- 3% of the theoretical value.

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 DC FM 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.