We demonstrate a flexible RF photonics down-converter that enables spectral folding of a 2-18 GHz RF band into a common 2 GHz wide intermediate frequency (IF) band for identification of specific signals of interest. The system can then be reconfigured for selective down-conversion of a given sub-band to a common IF output. We present an analysis of the performance of the down-converter and experimentally demonstrate both the spectral folding and selective modes. A sensitivity of -42 dBm in an IF bandwidth of 2 GHz and a spurious free dynamic range of 103 dB.Hz2/3 is achieved in the spectral folding mode.