The Agilent 83712B synthesized CW generator sets a new standard for performance at a price that is surprisingly affordable.  Fundamental oscillators and switched low-pass filters deliver <-55 dBc harmonics, eliminate subharmonics and suppress spurious to <-60 dBc. This signal source provides plenty of output power (typically >+14 dBm), while spectral purity is maintained even at high power levels (typical output power at frequencies below 1 GHz is +20 dBm).