The SR844 is the widest bandwidth lock-in amplifier available. It provides uncompromised performance with a frequency range of 25 kHz to 200 MHz and up to 80 dB of drift-free dynamic reserve. The SR844 includes the many features, ease of operation, and programmability that you've come to expect from SRS DSP lock-in amplifiers. The Stanford Research Systems SR844 lock-in amplifier has both 50ohm and 1 Mohm inputs. The 1 Mohm input is used with high source impedances at low frequencies, or with a standard 10× scope probe. The 50ohm input provides the best RF signal matching. The Stanford Research Systems SR844 is easy to use. All instrument functions are set from the front-panel keypad, and the knob is used to quickly adjust parameters. Up to nine different instrument configurations can be stored in non-volatile memory for fast, reliable instrument setup. Features: 25 kHz to 200 MHz frequency range 80 dB dynamic reserve Time constants from 100 µs to 30 ks (6, 12, 18 or 24 dB/oct rolloff) “No Time Constant” mode (10 µs to 20 µs update rate) Auto-gain, -phase, -reserve and -offset Two 16-bit DACs and ADCs Internal or external reference GPIB and RS-232 interfaces