Lock-In Preamplifier SR550 — FET input preamplifier · 3.6 nV/√Hz input noise · FET input, 100 MΩ input impedance · Gain of 1, 2, 5 or 10 · Single-ended and differential inputs · AC coupled input · High common mode rejection · Powered by SRS lock-in amplifiers The SR550 Voltage Preamplifier is designed to work with SRS lock-in amplifiers. Preamplifiers provide gain close to the experimental detector, before the signal-to-noise ratio is permanently degraded by cable capacitance and pickup. The SR550 minimizes noise and pickup in the connecting lines and reduces measurement time in noise-limited experiments. Power and control signals are brought from the lock-in by a 9-pin cable. The SR550 may also be operated independently by applying appropriate biasing (±20 VDC, +5 VDC). Input impedance 100 MΩ + 25 pF Inputs Single-ended or differential Maximum input 250 mVrms for overload 100 VDC, 10 VAC damage threshold Noise (typ.) 3.6 nV/√Hz at 1 kHz 4.0 nV/√Hz at 100 Hz 13 nV/√Hz at 10 Hz Coupling AC (0.016 Hz) CMRR (1 V input) 90 dB at 100 Hz Gain settings 1, 2, 5, 10 (automatically set by SR510 or SR530 lock-in) Full-scale sensitivity 10 nV to 200 mV Gain accuracy 2 % (2 Hz to 100 kHz) Gain stability 100 ppm/°C Outputs A (signal, 600 Ω, single-ended) B (shielded ground) Maximum output 7 Vpp Power Supplied by SR510, SR530, SR810, SR830, SR850 or SR124 via connector cable Mechanical 3.0" × 1.3" × 5.1" (WHD) Weight 1 lbs. Warranty One year parts and labor on defects in materials and workmanship Stanford Research Systems Lock-in preamplifier