These instructions are intended for the replacement of the A3 assembly in the 3458A that has been diagnosed with the short term drift problem described in Service Note 3458A-18.
The Product Note shows how to measuring jitter with the Keysight E4874A Characterization Software Components on the Keysight 81200 Data Generator/Analyzer Platform.
The attached downloadable 60501B Electronic Load Module Operating Manual is for use with Keysight model and serial numbers: Model 60501B: 3118A-00101 and Above