The theoretical premises and experimental results of phase control in high-power microwave oscillators with nanosecond pulse duration are presented. In experiments, two-channel backward wave oscillators (BWOs) for both steady state (100-150 cycles) and super-radiance (SR) mode operation (10-20 cycles) are discussed. For the phase control, the shift of the moment with fastest current rise is provided in the sections of nonlinear transmission lines with axially biased ferrites. The voltage pulse sharpening and shift of group velocity depend on the dc axial magnetic field. In SR mode, two-channel source is capable of producing 2 × 0.3 GW pulses with duration of 2 ns and the center frequency of 10 GHz. The source operates at the repetition rate up to 100 pps with electronic control of the phase in one channel relative to another. The last experiment is carried out using two synchronized compact RADAN-type drivers with two parallel Ka-band BWOs (100 MW, 2 ns, 37 GHz). The controllable shift of interference picture is a proof of the coherency in the aggregated radiation. At the maximum of the pattern in the far zone, the detector indicateds fourfold increase in power density over that measured from single channel.