The Berkeley Nucleonics Model 855B supplies up to four phase-coherent channels for radar simulation, phased-array and beamforming test, and electronic warfare, all in a single 1U rackmount. Five models cover 300 kHz to 6, 12, 20, 33 or 40 GHz. Each channel’s phase adjusts independently in 0.1° steps, with 0.096 ps typical channel-to-channel phase stability (5 GHz, 5 hours). Its 3 GHz clock ports synchronize multiple units for higher channel counts and automated test systems.