A tunable optical microwave generation scheme using self-injection locked monolithic dual-wavelength amplified feedback laser (AFL) is proposed and experimentally demonstrated. By using a dual-loop feedback scheme, the 3-dB linewidth of the optical microwave output resulting from mode beating is reduced from MHz to kHz scale. Optical microwave generation tunable from 30 to 38 GHz with 3-dB linewidth below 2 kHz is experimentally demonstrated.