|  Mechanical and ele ctronic step attenuators | 
  opt. 2  | 
|  Analog Sweep | 
  opt. 6  | 
|  IF Input | 
  opt. 7   | 
|  User-Defined Modulation Waveform Software | 
  opt. 10  | 
|  FM/Phase Modulation (ext.)  | 
  opt. 12  | 
|  Pulse Modulation (ext.) | 
  opt. 13   | 
|  AM (ext.) | 
  opt. 14   | 
|  LF Function Generator | 
  opt. 23   | 
|  Pulse Generator | 
  opt. 24  |