For example: Agilent E4440A or Anritsu 68369
Keithley Instruments Pulse Generators
Keithley Instruments 3401F
165MHz Single-Channel Pulse Generator, Front Connector
Manufacturer: Keithley Instruments
Keithley Instruments 3401R
165MHz Single-Channel Pulse Generator, Rear Connector
Manufacturer: Keithley Instruments