The National Institute of Standards and Technology (NIST) is seeking responses for a Sources Sought notice regarding the procurement of a Microwave Phase Noise Analyzer. The analyzer is required to measure phase noise and frequency stability of microwave signals, which is critical for the NIST's research in precision timekeeping and navigation using nanophotonics. The instrument must meet specific technical specifications, including the ability to accept input signals from 1 MHz to at least 100 MHz and perform long-term frequency stability measurements. Interested vendors should submit their capabilities and relevant information to Cielo Ibarra at cielo.ibarra@nist.gov by the deadline of June 13, 2025, for any questions regarding the notice.