Traditional methods used to characterize multi-carrier distortion products are insufficient for the needs of emerging HFC systems. Noncoherent (free-running) oscillators, which have generally been used to test CTB and CSO products, do not provide the means to characterize perfonnance of HFC system components under various conditions of peak power factor. Since HFC systems are particularly sensitive to distortions and signal clipping resulting from intermittently high peak factors, the ability to control the peak factor of the multi-carrier test signal is crucial. New test methodology is described that allows the characterization of system components using a multi-carrier signal with precisely controllable peak factor.