Diversified Technologies, Inc. (DTI), in partnership with SigmaPhi Electronics (SPE), has built three long pulse solid-state klystron transmitters to meet European Spallation Source (ESS) requirements. The prototype system was built under a DOE SBIR effort, and the first production modulators were built for, and installed at, CEA Saclay, Franc, and the National Institute of Nuclear and Particle Physics (IN2P3) in Orsay, France, where they will be used in support of RF component development and testing.