The DL Instruments / Ithaco 1201 is a low-noise voltage preamplifier engineered for acquisition of weak signals in laboratory and field environments. It delivers selectable gain from 10 to 25,000 with 1% accuracy and exceptional stability, combined with ultra-high input impedance and superior common-mode rejection. The instrument operates in AC or DC coupled modes and supports both differential and single-ended inputs, making it ideal for precision measurements where signal fidelity and noise performance are critical.
## Technical Specifications
**Gain & Stability**
• Selectable gain: 10 to 25,000
• Gain accuracy: 1%
• Gain stability: Better than 0.03%/°C
• Discrete steps: 1-2-5 sequence from ×10 to ×10,000
• Variable gain control: ×2.5 multiplication factor
**Input Characteristics**
• DC coupled input impedance: Typically 5 GΩ; minimum 1 GΩ
• AC coupled input impedance: 100 MΩ per BNC input
• Input current: Less than 10 pA (either input); less than 5 pA offset current
• Common-mode rejection ratio: Above 125 dB
• Maximum differential/single-ended input: ±750 mV (gains ×10–×100); ±75 mV (gains ×200–×10,000)
• Maximum common-mode input: 10 V pk-pk; 200 Vdc in AC mode
**Frequency Response**
• DC coupled: DC to 400 kHz (−3 dB) at maximum low-pass position
• AC coupled: 0.008 Hz to 400 kHz (−3 dB) at maximum low-pass position
• High-pass filter: DC or 0.03 Hz to 3 kHz (1-3-10 sequence, 6 dB/octave)
• Low-pass filter: DC or 3 Hz to 300 kHz and MAX (1-3-10 sequence, 6 dB/octave)
**Performance**
• Noise figure: Less than 0.4 dB at 1 kHz with 1 MΩ source impedance
• DC stability (temperature): 6 µV/°C maximum referred to input
• DC stability (time): 20 µV/24 hr maximum after 30-minute warm-up
• Distortion: 0.01%
• Output impedance: 600 Ω and 50 Ω options available; low-impedance output to 25 mA
**Power**
• Input: 100–130 VAC or 200–260 VAC (switch selectable), 50–60 Hz, 10 watts
• Battery operation: Greater than 25 hours; charge time less than 15 hours
• Dual charge modes: Fast charge and trickle charge selectable
## Key Features
• Gated external input control on rear panel
• Discrete gain selection minimizes crosstalk and noise
• Switchable AC/DC coupling and filter configurations
• Portable battery/line operation
## Typical Applications
Evoked potential measurements, infrared radiometry, and other instrumentation requiring low-noise amplification of submillivolt signals.
