Model LN310 is a fast-switching frequency synthesizer from Programmed Test Sources that offers better than 5-microsecond switching speed across the 1 to 310 MHz frequency range. The synthesizer features 0.1-Hz frequency resolution with better than -80 dBc spurious content and single-sideband (SSB) phase noise of -152 dBc/Hz offset 100 kHz from a 100-MHz carrier. The frequency synthesizer includes a binary-coded-decimal (BCD) control interface as well as local-area-network (LAN), GPIB, and Universal Serial Bus (USB) interfaces for flexibility in automatic-tes-equipment applications.