  Presently, the manufacturing of active RF devices like klystrons is dominated
by expensive and time consuming cycles of machining and brazing. In this
article we characterize the RF properties of X-band klystron cavities and an
integrated circuit manufactured with a novel additive manufacturing process.
Parts are 3D printed in 316L stainless steel with direct metal laser sintering,
electroplated in copper, and brazed in one simple braze cycle. Standalone test
cavities and integrated circuit cavities were measured throughout the
manufacturing process. Un-tuned cavity frequency varies by less than 5% of
intended frequency, and Q factors reach above 1200. A tuning study was
performed, and unoptimized tuning pins achieved a tuning range of 138 MHz
without compromising Q. Klystron system performance was simulated with as-built
cavity parameters and realistic tuning. Together, these results show promise
that this process can be used to cheaply and quickly manufacture a new
generation of highly integrated high power vacuum devices.
