Brand

Used Keithley test equipment

Joseph F. Keithley started Keithley Instruments in Cleveland in 1946. His first product, the Phantom Repeater, amplified weak signals, and an electrometer is what made the company. That focus on tiny currents and voltages runs through the gear people hunt for today, from picoammeters to the SourceMeter line, which pairs a stable power source with a 6½-digit meter in one box. The company moved to Solon, Ohio, in 1964. Danaher bought Keithley in 2010 and merged it into Tektronix, and in 2011 it said most manufacturing would move from Ohio to China. Keithley is now a brand of Tektronix, which became part of Ralliant when Fortive spun that business off in 2025.

6 models we cover.