The El00 Model 320 Signal Generator cons ists of a highly static Hartly RF Oscillator, covering a frequency range of ISO kc to 34 me, with strong harmonics to 102 dig* This entire range is calibrated on the dial in seven (7) ranges. The RF Oscillator is K of a 6SN7 tube» Variable outpat is taken from the cathode* The other half of the 6SN7 is a colpitts type sudio oscillator providing 400 cycle pure sine ware output which is also utilised-to modulate the RF oscillator* An at tenuator provides variable audio voltage*