Keithley 103A Nanovolt Amplifier Dual Input Low Noise BNC Benchtop Lab

Keithley 103A Nanovolt Amplifier Dual Input Low Noise BNC Benchtop Lab

The Keithley 103A is a benchtop nanovolt amplifier designed to amplify very low-level DC and AC signals with high gain and low noise. It accepts two differential BNC inputs (Input A and Input B) and provides two separate outputs — Low Out and High Out — allowing simultaneous monitoring or use with different measurement instruments. A front-panel rotary control sets the 3dB frequency cutoff from 0.1 Hz to 100 kHz, and a separate Gain/Adjust knob controls amplification with a CAL reference position. This unit came to us from a retiring electrical engineer who used it in his calibration and product development electronics lab.

Specifications & What's Included

• Make: Keithley Instruments, Cleveland, Ohio
• Model: 103A Nanovolt Amplifier
• Form factor: Benchtop enclosure
• Inputs: Dual BNC — Input A and Input B (differential)
• Input selector switches: A-B and -B modes; Overload indicator and Reset button
• Outputs: Two BNC — Low Out and High Out
• 3dB Frequency control: Rotary dial, 0.1 Hz to 100 kHz (100, 300, 1k, 3k, 10k, 30k, 100k Hz positions)
• Gain control: Rotary Adjust knob with CAL position
• Rear panel: Power Input ±15 Volts @ 150 mA; DC Output Adj (two trim knobs)
• Power cable: Blue-connector power cable attached
• Included: Unit with attached multi-wire input lead assembly (spade terminals)

Applications

Nanovolt amplifiers like the Keithley 103A are used in precision measurement applications where signal levels are too small to work with directly — typically in the nanovolt to microvolt range. They are a standard tool in calibration laboratories, thermocouple and thermometry measurement setups, low-noise sensor signal conditioning, and precision DC/AC measurement research. The dual-input differential configuration allows the amplifier to reject common-mode noise while amplifying the true signal difference between two sources. The 3dB frequency selection makes it suitable for both DC-coupled very-low-frequency work and AC signal amplification up to 100 kHz. Keithley Instruments, founded in the late 1940s and based in Cleveland, Ohio, built a strong reputation for precision low-level measurement instruments; the 103A dates from the analog-instrumentation era of the 1960s–1970s when Keithley was a leading maker of electrometers, nanovoltmeters, and signal amplifiers for laboratory and calibration use. These instruments remain in use today wherever legacy precision measurement setups are maintained or where a simple, reliable analog low-noise amplifier is preferred.