An rf pulse compressor has a single high Q cavity resonator fed by a four port hybrid coupler which is connected to the resonator at coupling ports located at the intersection of two of the resonator's orthogonal axes with the resonator cavity walls. The hybrid coupler divides pulse power from an rf pulse power source and excites two space and phase orthogonal modes in the single cavity, the stored energy of which aids in producing compressed pulses at the output of the hybrid. On-axis perturbations in the cavity walls can be used to lock the orthogonal orientation of the modes excited in the cavity.