Summary form only given. This article discusses a proposal for an ultra fast feedback response that will protect the load and solid state switches of the on/off Marx type modulators. The feedback guards main elements of a modulator against possible arcs in the load, particularly arcs inside of the electron guns. The chief concept behind the proposed response system is an employment of a fraction of the output modulator power as a controlling and guarding pulse during the delivery time. The time constant of the proposed feedback loop lies in the nanosecond range. Peculiarities of proposed topology are discussed.