Scitec Instruments 420 Manual

Scitec Instruments' Model 420 analogue dual phase lock-in amplifier uses advanced
technology to provide a high performance instrument which is both versatile and easy to
use.
• Dual phase operation with modulus (R) calculation
• Differential or single-ended input
• Gain settings from 3µV to 1V
• High performance wide bandwidth input gain stage
• Analogue meter for display of X, Y or R output signals
• Separate X, Y and R output BNCs
• X & Y Offset controls
• Output time constants from 100µs to 30s
• 1F and 2F reference signal operation
• 90° step and fine phase control
SCITEC INSTRUMENTS
INPUT
100mV 30mV 3S 1S
300mV 10mV 10S 300mS
1V 3mV 30S
3µV 1mV 100µS
10µV 300µV 300µS 10mS
30µV 100µV 1mS 3mS
SENSITIVITY TIME CONSTANT

INPUT SIGNAL CHANNEL

The input signal channel amplifies the input signal to a level suitable for the
Demodulator. High performance, low-noise, broad-band amplifiers are used throughout.
The input circuit can accept a differential or single-ended input via the front panel signal
input BNC. Jumper options within the unit allow the outer BNC contact or screen to act
as a high impedance differential input, as a low impedance (100Ω) differential input or
allow it to be connected to ground for single-ended operation.
The input channel can be either AC or DC coupled via internal jumper selection. It is
recommended that the unit is used in DC coupled mode as the noise performance is
improved. In this mode, through the careful design of the lock-in, up to ±10V of DC
offset is allowed before saturation for gain settings from 1V to 300µV, ±1V of DC offset
for gain settings from 100µV to 10µV and ±300mV of DC offset for the gain setting of
3µV.
Input High or low impedance differential or single ended via front panel BNC
Sensitivity 3µV to 1V (for 1V output) switched in 1, 3, 10 steps
Input Impedance
10
Frequency 10Hz to 100kHz
Maximum Inputs ±16V before input protection circuitry comes into operation. The input BNC has
Boston Electronics Corporation, 91 Boylston Street, Brookline MA 02445
(800)347-5445 or (617)566-3821 * fax (617)731-0935 * boselec@boselec.com * www.boselec.com
Dual Phase Lock-In Amplifier
OUTPUT
X Y
100mS
0V 0V
ON X
30mS
-1V 1V -1V 1V
OFF Y
OFFSET CONTROL OUTPUT SELECT
12 Ω1nF, dc coupled
Model 420
REFERENCE
270° 0°
180°
90°
50°
R
0°
100°
PHA SE SHIFT
420 DUAL PHASE LOCK-IN AMPLIFIER
DISPLAY
2F
1F
POWER