A multiple frequency source system includes at least one frequency source tunable to a predefined target frequency, and at least one additional frequency source operable to generate a second signal at a frequency which is either higher or lower than the target frequency. A method for tuning the tunable frequency source to the target frequency during concurrent generation of the second signal includes (i) controlling the tunable frequency source to tune to at least one frequency point frequency lower than the target frequency, and thereafter controlling the oscillator to tune to the target frequency, when the second signal is higher in frequency than the target frequency, or (ii) controlling the tunable frequency source to tune to at least one frequency point higher than the target frequency, and thereafter controlling the tunable frequency source to tune to the target frequency, when the second signal is lower in frequency than the target frequency.