Stanford Research Systems SR800 Series Lock-In Amplifiers
2 models with full specifications from Stanford Research Systems.
The Stanford Research Systems SR800 series represents a family of high-performance DSP-based lock-in amplifiers designed for precision scientific and engineering measurements. This series, which includes the SR830 and SR850, is characterized by exceptional dynamic reserve, low drift, and high stability. By replacing traditional analog demodulators with digital signal processing (DSP) architectures, these instruments overcome many of the drift and noise limitations inherent in analog designs. They operate across a wide frequency range from 1 mHz to 102.4 kHz, making them suitable for a broad spectrum of phase-sensitive detection tasks. Whether conducting low-noise voltage measurements or highly sensitive current detection, this series provides researchers with the necessary tools to extract weak signals from noisy environments. This guide highlights their common design characteristics and key differences to assist technical buyers and engineers in selecting the correct instrument.
- Frequency Range
- 1 mHz to 102.4 kHz
- Dynamic Reserve
- >100 dB (without pre-filtering)
- Preamplifier Power Output
- ±15 VDC, 100 mA max
- Supported Interfaces
- GPIB, RS-232
Models in this series
Shared Architecture and Core Performance
Both the Stanford Research Systems SR830 and SR850 rely on a digital signal processing architecture that replaces traditional analog mixers and filters. This design choice allows both models to offer a dynamic reserve exceeding 100 dB without relying on band-pass tracking filters or analog pre-filtering. They share a common frequency range of 1 mHz to 102.4 kHz and provide standard rear-panel preamplifier power output connectors delivering ±15 VDC at up to 100 mA to support external preamplifiers. Additionally, both units include GPIB and RS-232 interfaces for remote programming, integration into automated test setups, and data acquisition.
Comparative Capabilities and Phase Precision
While sharing basic frequency and dynamic reserve characteristics, the two models differ significantly in interface capabilities and phase resolution. The SR850 is a high-performance unit offering advanced phase analysis, featuring an outstanding phase resolution of 0.001°, channel orthogonality within 0.001°, and low reference phase drift (<0.01°/°C below 10 kHz). The SR850 also includes automated routines—specifically auto-gain, auto-phase, auto-reserve, and auto-offset—along with a 3.5" floppy disk drive and a flat panel display (or CRT on older revisions). In contrast, the SR830 is a dual-phase lock-in amplifier utilizing dual 4.5-digit LED displays with 40-segment LED bar graphs. The SR830 operates over a wider temperature range of 0 to 50 °C (compared to 0 to 40 °C for the SR850) and has a lighter physical footprint, weighing 13.6 kg compared to the SR850's 18.1 kg.
Frequently asked questions
- What is the dynamic reserve of the SR800 series models?
- Both the SR830 and SR850 offer a dynamic reserve of greater than 100 dB without requiring analog pre-filtering or band-pass tracking filters.
- How do the display systems differ between the SR830 and SR850?
- The SR830 uses dual 4.5-digit LED displays accompanied by 40-segment LED bar graphs, while the SR850 features a larger flat panel display (or CRT display on older revisions) for presenting measurement data and menu options.
- What are the input configurations for the SR830?
- The SR830 supports single-ended (A) or differential (A-B) voltage input configurations with an impedance of 10 MΩ + 25 pF, as well as current input configurations with gain-dependent impedance of 1 kΩ or 100 Ω to virtual ground.