The generation of high power microwaves using explosively driven pulsed power is of particular interest to the defense community. The high energy density of explosives provides the opportunity to design pulsed power systems which occupy significantly less volume, yet provide the same output power, as traditional methods of High Power Microwave (HPM) production. Utilizing a Flux Compression Generator (FCG) as explosive driver necessitates introducing an intermediate Power Conditioning System (PCS) that addresses the typical impedance mismatch between FCG and HPM source. The presented PCS is composed of an energy storage inductor, an opening fuse switch and a self-break peaking gap all of which needed to fit within an envelope of 15 cm diameter. Currents in the tens of kilo-amperes and voltages in the hundreds of kilo-volts have to be handled by the PCS. The design of the system, which takes up less than 11 liters of volume, as well its performance into a 20 Ω resistive load (used to approximate the operating impedance of certain HPM sources) is presented. Approximately 6 GW of electrical peak power was delivered to the load.