Upgrading the 250kW CW X-band klystron used in the goldstone solar system radar

The Goldstone Solar System Radar (GSSR), part of the Deep Space Network (DSN), utilizes a 70 meter antenna and a 500kW CW transmitter powered by two VKX-7864B, 250kW CW X-band (8560 MHz) klystrons. The VKX-7864B klystron, developed in 1988, required improvements in power output, bandwidth, and reliability to ensure long term system sustainability and to support demands of future DSN/GSSR critical missions. CPI reviewed klystron subassemblies historical failure modes, performed simulations with State-of-the-Art computer codes, and identified improvement opportunities. Improvements in the beam optics, RF circuits gain, bandwidth, and efficiency, collector dissipation, coolant flow, thermal stability, and mechanical reliability were implemented in a high reliability klystron upgrade, designated the VKX-7864C. All performance goals were met or exceeded. Power output > 250kW CW over entire 50 MHz bandwidth, gain > 51dB, efficiency > 45%, RF beam transmission > 99.99%. This paper presents some important improvements of this klystron development.