Editing Variable-frequency oscillator (section)

===Repeatability===
Ideally, for the same control input to the VFO, the oscillator should generate exactly the same frequency. A change in the calibration of the VFO can change receiver tuning calibration; periodic re-alignment of a receiver may be needed. VFO's used as part of a [[phase-locked loop]] frequency synthesizer have less stringent requirements since the system is as stable as the crystal-controlled reference frequency.