Figure 11: Input And Offset Range For X 100 Gain - Tektronix ADA400A Instruction Manual

Reference
Adjusting the Offset
Controls
Limiting Bandwidth
18
+10V
+1V
Maximum
Differential and
Single-Ended Input
+100mV
- - 100mV
- - 1V
- - 10V

Figure 11: Input and Offset Range for X 100 Gain

Setups that have a large DC offset, but must measure small changes in DC
voltage or signal voltage below 2 Hz, require that you to adjust the offset
controls of the preamplifier. Typical setups include those with transducers or
setups that measure galvanic potentials.
To compensate for a DC offset, perform the following procedure:
1. Set the input coupling to GND on both inputs of the preamplifier and switch
offset controls to OFF.
2. Preset the GAIN switch of the preamplifier and the volts/division switch of
the oscilloscope to the appropriate settings based on the amount of offset you
expect to measure. See Figures 8 through 11. (Select a lower gain setting if
you are unsure of the amount of the offset.)
3. Center the oscilloscope display using the vertical position control on the
oscilloscope.
4. Set the offset controls ON and center the display with the COARSE and
FINE offset controls.
5. Set the input coupling to DC on the signal input(s) and, if necessary,
measure the amount of DC offset.
6. Center the display using the COARSE and FINE controls and change the
volts/division setting on the oscilloscope to better display the signal.
The ADA400A Differential Preamplifier has a selector for limiting the upper
bandwidth. Limiting the bandwidth is desirable in setups where electrical
interference from higher frequency sources is a problem. The ADA400A
Common Mode
Offset Range
Range
ADA400A Differential Preamplifier