Voltage‐biased superconducting weak contacts have been used as oscillating detectors to observe radio‐frequency absorption spectra including the Co59nuclear magnetic resonance in ferromagnetic cobalt. The detection is attributed to multiple quantum processes and differentiation of the dynamic I‐V characteristics. Used as a spectrometer, the point contact is shown to be a continusously tunable ultra‐low power oscillator‐detector from 0 to 3 × 108Hz. It is likely that the frequency limit could be extended to the superconducting gap frequency.