Measurements

Grid Dip Oscillator (GDO) (2)

  • If the tuned circuit of an lightly oscillating valve LC oscillator is brought near (coupled with) a tuned circuit with the same resonant frequency a dip in the grid current will occur
  • This is the principle of the GDO, though nowadays it is a dip in base current or drain current of a transistorised unit
  • As a dip in current indicates resonance, a GDO is often called a Dip Meter
  • The unit has a series of plug-in coils and a calibrated tuning dial to vary frequency, allowing a wide range of resonant frequencies to be measured