A new concept of an harmonic phase-locked hair-pin oscillator is presented. It comprises a FET biased in the saturation region which leads to high output power both at the first and second harmonic. The second harmonic frequency is utilized as the main output signal at K band, while the fundamental signal is used as the phase locked stabilized frequency. The oscillator design includes high Q hair-pin resonators. The circuit is easy to be integrated. The measured phase noise of the free-running oscillator is about -105dBc/Hz at an offset frequency of 200 kHz.