For example: Agilent E4440A or Anritsu 68369
Aeroflex
Aeroflex IMD-803D-02
IMD-803D-02 Intermodulation Distortion Simulator

Category: Signal Gen/Synthesizers/Sweepers
Aeroflex NAV-2000R
VOR/LOC/GS/MB/COMM/SELCAL/ADF Signal Generator w/ DSP and GPIB

Category: Signal Gen/Synthesizers/Sweepers