Tektronix TEKFAX ADA400A, Instruction Manual

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Getting Started
4
ADA400A Differential Preamplifier
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.
Functional Check
The following procedure checks the output level of the ADA400A Differential
Preamplifier and the functionality of the offset controls with no signal applied.
1.
Without any connection on the input of the oscilloscope, power on the
oscilloscope and make the following control settings:
Volts/Division 100 mV
Time/Division 100 s
Input Coupling DC
Input Impedance 1 M
Ω
2.
Adjust the oscilloscope to display a flat signal trace at center screen.
3.
Connect the output of the ADA400A Differential Preamplifier (or 1103
TEKPROBE Power Supply) to the input connector of the oscilloscope.
4.
With no input signal or voltage connected, make the following control
settings on the ADA400A Differential Preamplifier:
AC GND DC GND (both inputs)
GAIN 0.1
OFFSET OFF
UPPER BANDWIDTH FULL (1 MHz)
5.
Check that the trace on the oscilloscope centers around zero volts and the
OVERRANGE indicator
does not
light.
6.
Set the
GAIN
switch to each of the higher gain settings and check that the
trace on the oscilloscope is adjustable to center screen. Make sure the
volts/division reading on the scope matches the readings below in table 1. If
the readings do not match, the oscilloscope is not compatible with the scale
factor coding of the ADA400A Differential Preamplifier. See page 2. If the
scale factor coding is disabled, see table 3 on page 10 for proper readings.
Check the Oscilloscope
Input Impedance and
Coupling