DDS Based AM Exciter

  • Accurate and stable DDS oscillator, based on the AD9851 from Analog Devices Inc.
  • Direct amplitude modulation of the DDS’s DAC with mod and carrier level control
  • Low noise, high dynamics Norton type preamplifier
  • Highly linear Class A Push-Pull final
  • 10W peak / 2.5W carrier (capable of 16 W peak / 4W carrier)
  • PA overcurrent protection


The exciter is at a prototype / proof of concept stage. Control, protection and boxing is yet to come, although it’s developed and being prepared. On the following shots you can see the output signal at 16 W peak power into 50 ohms and the workbench setup for the test. The unit is modulated with a GN-4 audio lab generator.