SR551 High Impedance Preamp
The SR551 High Impedance Preamplifier works with SRS lock-in amplifiers to measure voltages from sources with moderate to high source impedance. The preamplifier is designed for source impedances of up to gigaohms with little error from resistive loading, due to its exceptionally high 1 TΩ input impedance. The SR551 operates with a fixed voltage gain of ×10, amplifying signals from DC to 1 MHz. Power and control signals are brought from an SRS lock-in amplifier by a 9-pin cable (included). The SR551 may also be operated independently by applying appropriate power supply voltages (±20 VDC).