Signal Channel Voltage inputs Single-ended or differential Sensitivity 2nV to 1 V Current input 106 or 108  Volts/Amp Impedance Voltage: 10 MW + 25 pf, AC or DC coupled Current: 1 kW to virtual ground Gain accuracy > ±0.2% Noise 6 nV/ÖHz at 1 kHz (typical) 0.13 pA/ÖHz at 1 kHz (106 V/A) 0.013 pA/ÖHz at 100 Hz (108 V/A) Line filters 60 [50] Hz and 120 [100] Hz notch (Q=4 ) CMRR 100 dB to 10 kHz, decreasing by 6 dB/OCT above 10 kHz Dynamic reserve >100 dB without prefilters (<5 ppm/°C) Reference Channel Frequency range 0.001 Hz to 102 kHz Reference input TTL or sine (400 mVp-p minimum) Input impedance 1 MW, 25 pf Phase resolution 0.01° front panel, 0.008° through computer interfaces. Absolute phase error <1° Relative phase error <0.001° Orthogonality 90° ± 0.001° Phase noise        Internal reference     Synthesized, <0.0001°rms at 1 kHz.      External reference  0.005° rms at 1 kHz, 100 ms, 12 dB/oct. Phase drift <0.01°/°C below 10 kHz, <0.1°/°C below 100 kHz. Harmonic detection 2F, 3F, ... nF to 102 kHz (n <19,999). Acquisition time 2 cycles + 5 ms or 40 ms (largest applies) Demodulator Stability Digital outputs and display: no drift. Analog outputs: <5 ppm/°C for all dynamic reserve  settings. Harmonic rejection -90 dB Time constants 10 ms to 30 ks (6, 12, 18, 24 dB/oct rolloff). Synchronous filters available below 200 Hz Internal Oscillator Range 1 mHz to 102 kHz Frequency accuracy 25 ppm + 30 mHz Frequency resolution 4 1/2 digits or 0.1 mHz, whichever greater Distortion -80 dBc (f <10 kHz), -70 dBc(f >10 kHz) @ 1 Vrms amplitude Amplitude 0.004 to 5 Vrms into 10 kW (2 mV resolution), 50 W output impedance, 50 mA maximum current into 50 W Amplitude accuracy 1% Amplitude stability 50 ppm/°C Outputs Sine, TTL Displays Channel 1 4 1/2 digit LED display with 40 segment LED bar graph. X, R, X-noise, Aux 1 or Aux 2. The display can also be any of these quantities divided by Aux 1 or Aux 2. Channel 2 (SR830) 4 1/2 digit LED display with 40 segment LED bar graph. Y, q, Y-noise, Aux 3 or Aux 4. The display can also be any of these quantities divided by Aux 3 or Aux 4. Offset X, Y, R can be offset ±105% of full scale Expand X, Y, R can be expanded by 10 or 100 Reference 4 1/2 digit LED display Inputs and Outputs CH1 output ±10 V output of X, R, X noise, Aux 1 or Aux 2.  Updated at 512 Hz. CH2 output (SR830) ±10 V output of Y, Y noise, Aux 3 or Aux 4. Updated at 512 Hz. X, Y outputs In phase and quadrature components (±10 V), updated at 256 kHz (rear panel) Aux. A/D inputs 4 BNC inputs, 16 bit, ±10 V, 1 mV resolution, sampled at 512 Hz. Aux. D/A outputs 4 BNC outputs, 16 bit, ±10 V, 1 mV resolution Sine Out Internal oscillator analog output TTL Out Internal oscillator TTL output Data Buffer 8,000 points (SR810), 2 x 16,000 points (SR830) Data Storage Rate Up to 512 Hz Trigger In TTL signal synchronizes stored data recording Remote pre-amp Provides power to the optional SR550, SR552, and SR554 preamplifiers. General Interfaces GPIB and RS-232 interfaces standard. All instrument functions can be controlled and read through GPIB or RS-232 interfaces. Power 40 Watts, 100/120/220/240 VAC, 50/60 Hz. Dimensions 17"W x 5.25"H x 19.5"L Weight 23 lbs.