The Model 855B fits up to four phase-coherent signal generator channels in a 1U rackmount, covering 300 kHz to 6, 12, 20, 33 or 40 GHz. Maximum output power is +25 dBm, and Option FS cuts switching to 25 µs. Typical channel-to-channel phase stability is 3 mrad (0.096 ps) at 5 GHz over five hours. Its 3 GHz clock ports synchronize multiple units for radar simulation, phased-array beamforming test, quantum computing, EW and SATCOM R&D.