The CLW modulator represents the first successful application of high-power IGBT switching modules to meeting the requirements of multi-megawatt peak power modulators for microwave amplifier applications. Unlike some other solid-state modulators, no semiconductorswitches are placed in series in this system. Neither are the switches connected in parallel. Rather, each switch drives a segment of the pulse transformer core, in a configuration we refer to as a "fractional-turn primary" arrangement. As no PFN is required the width of the output pulse can be adjusted by simply adjusting the trigger duration of the IGBT switches and no PFN ripple occurs on the pulse-top. The volume of the complete modulator is about 10% of a classical unit of the same power. The advantages of this new concept will be discussed with details of a unit that has been in continuous use for more than two years.Presenting Author : Crewson W.