For example: Agilent E4440A or Anritsu 68369
Mixers
Keysight / Agilent 11974
Preselected millimeter mixers 26.5GHz- 75GHz

Manufacturer: Keysight / Agilent
Keysight / Agilent 5086-7748
Microcircuit - Low Band Microwave Mixer Assembly

Manufacturer: Keysight / Agilent
Keysight / Agilent 5086-7908
1st Converter, Low Band Mixer, DC- 2.9 GHz

Manufacturer: Keysight / Agilent
Keysight / Agilent 5086-7952
Microcircuit - Dual Band Microwave Mixer Assembly

Manufacturer: Keysight / Agilent
Keysight / Agilent 5087-7183
TBR Routing Yig Tuned Harmonic Mixer, 13.2 GHz

Manufacturer: Keysight / Agilent