For example: Agilent E4440A or Anritsu 68369
Converter
Keysight / Agilent 43521A
Keysight Agilent 43521A Downconverter Unit, 10 MHz to 12.6 GHz
Manufacturer: Keysight / Agilent
Keysight / Agilent 5086-7819
HP Agilent Keysight 5086-7819 Second Converter for use w/ 8590 Series
Manufacturer: Keysight / Agilent