A variable frequency oscillator (VFO) in electronics is an oscillator whose frequency can be tuned (i.e., varied) over some range.[1] It is a necessary component in any tunable radio transmitter and in receivers that work by the superheterodyne principle. The oscillator controls the frequency to which the apparatus is tuned.
- ^ Larry D. Wolfgang, ed. (1991). The ARRL Handbook for Radio Amateurs, Sixty-Eighth Edition. Newington, Connecticut: American Radio Relay League. Chapter 10. ISBN 0-87259-168-9.