Abstract: An RF window and a method of manufacture of the RF window are provided. The RF window of the invention has very low reflected RF power. The RF window includes a center sleeve assembly including a ceramic disc mounted within a copper sleeve. The ceramic disc has opposed surfaces, a ceramic surface coating is applied to each of the opposed surfaces. The ceramic surface coatings are selected for a particular application of the RF window. A pair of end assemblies is removably assembled with the center sleeve assembly. An end assembly mating face is arranged for adjustable slip fit engagement within the copper sleeve of the center sleeve assembly to define a respective cavity on opposed sides of the ceramic disc with the mating face positioned at an adjusted position. An intermediary ring is fixedly secured to the end assembly with the mating face at the adjusted position.