Mod Source Relative Gain

This adjustment corrects for the differences in the FM source signal paths. During this adjustment, scaling factors are determined for each FM source signal path for a given modulation signal level. The FM deviation is the same and independent of the signal source or the signal path.

This adjustment starts by setting the signal generator to 1 GHz with an FM deviation of 117.1875 kHz. The INT1 path is selected and the modulation level is set to 0 V. The output frequency is measured using a frequency counter and stored. The modulation level is then changed to –2.5 V and the output frequency is measured. The difference between the two frequencies is compared to a target deviation and used to determine a scaling factor. The process for calibrating EXT1 and EXT2 paths and determining the scaling factors is the same except that a function generator is used to provide a modulation level of 1 V and a digital multimeter is used to set the modulation level.

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]

Function Generator

33622A

33611A
33612A
33621A

33250A
33120A Opt 001

Digital Multimeter

3458A Opt 002

34470A

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.

 

Setup 1

 

Setup 2

 

Setup 3

 

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.