Abstract: A method and a stable local oscillator system for providing a signal centered at a frequency of interest to a radio frequency (RF) converter. The method includes the following steps: (a) generating an output signal which comprises a fundamental signal centered at a fundamental frequency and a harmonic signal centered at the frequency of interest which is equal to an integral multiple of the fundamental frequency; (b) amplifying the output signal such that the harmonic signal is amplified more than the fundamental signal; and (c) bandpass filtering the amplified output signal such that the amplified fundamental signal is substantially suppressed and the amplified harmonic signal is used as a local oscillator in the RF converter. An example is given for the case where the fundamental frequency is 1.67 gigahertz (GHz), and the frequency of interest is 3.34 GHz which is the second harmonic.