Tektronix TEKFAX ADA400A, Инструкция по эксплуатации

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Reference
ADA400A Differential Preamplifier
15
Input
Oscilloscope
Circuit
Under Test
Differential
Amplifier
Common Ground
+
--
Figure 7: Eliminating Ground Loops in a Differential Setup
Always set the input impedance of the oscilloscope to 1 M
Ω
and the input
coupling of the oscilloscope to DC. Setting the impedance to 50
Ω
loads
(reduces) the amplitude of the output signal from the ADA400A Differential
Preamplifier. AC coupling on the oscilloscope interferes with the signal output.
Use the input coupling switch on the preamplifier to select other types of signal
coupling.
Setting the Controls
The controls of the ADA400A Differential Preamplifier determine signal
coupling, amplification, DC offset, and the bandwidth limit.
The type of input coupling you select depends on whether or not you want to
pass or block the DC component of the input signal.
AC Coupling.
Setting the coupling switch to AC places a capacitor in the signal
path and blocks DC to about 2 Hz signals. Select the AC position to block DC
components on the signal input and couple AC signals higher than approximate-
ly 2 Hz. This setup is useful when the test setup has a DC bias which drifts.
NOTE
. To prevent the circuit under test from receiving the effects of charging and
discharging the AC coupling capacitor, refer to the procedure for Precharging
the Signal Input in the section that follows.
Oscilloscope Input
Impedance and Coupling
Input Coupling