Synthesizer FM (Bessel) Calibration (Adjustment)

(N5166B / N5171B / N5172B / N5181B / N5182B / N5182N Option UNT)

All frequency accuracy calibrations must be performed prior to this adjustment.

This adjustment calibrates the out-of-band FM gain. For triple-loop instruments (N5181B/N5182B/N5182N), this involves both the frac-n and sum loops to be calibrated. For single-loop instruments (N5166B/N5171B/N5172B), this only involves the sum loop.

The adjustment for triple-loop instruments is done in two steps. The first is an internal DC adjustment that requires no external measuring device. This gets the cal values close to the desired value. The second step utilizes a spectrum analyzer and uses the Bessel-null approach. For single-loop instruments, only the second Bessel-null cal is performed on the single sum loop.

Required Test Equipment

Test Equipment

Recommended Model

Alternate Model(s)

Spectrum Analyzer

PXA N9030B Option Pxx1

 

PXA N9030A Option Pxx1

PSA models Option [1DS or 110]1:
E4440A
E4443A
E4445A
E4446A
E4447A
E4448A

  1. Preamp option (Pxx for PXA, 1DS or 110 for PSA) is recommended but not required.

 

Connections and Setup Procedures
  • All test equipment requires a 30 minute warmup period to ensure accurate performance.
  • In the following setup, cables are designated as solid lines and direct connections are designated as dashed lines.

Initialize Test Equipment

  1. Connect all test equipment as shown.
  2. Preset all test equipment and the signal generator.

 

Setup for Synthesizer FM (Bessel) 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. Refer to the troubleshooting section of the 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 necessary, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.