Tektronix ADA400A Instruction Manual page 17

Operating Basics
Table 1: Controis, Connectors, and indicators
Feature Description
~ ) | Input BNCs, The BNC connectors provide the differential input connections to the
i (3) © © OS ! preamplifier. These connectors accept coaxial cables, 1X probes, adapters, or other input
| f- | | leads that terminate with male BNC connectors. Before connecting the Inputs, see
J | page 9.
NOTE. Avoid using attenuating probes. The slightest difference in attenuation match
+ Input BNC ~ Input BNC greatly lowers the common-mode rejection ratio,
Connector Connector
x
+ Input
Fuse
~ Input
Fuse
Input Fuses. The input fuses and internal circuitry protect the input circuits from
excessive surge currents, To replace the fuses, see page 47.
a0v MAX
Selectable Impedance. Interna! jumpers select infinite impedance for measuring signals
with high source impedance. To select the input impedance, see page 10.
Input Coupling Switches. Use the input coupling switches to select the proper mode for
ac la coupling the input signals to the internal inputs of the preamplifier.
GND
be | The AC position couples the input signal through a capacitor and blocks any DC and AC
— components of the signal from 0 to 2 Hz.
GND decouples the signal from the input and couples the internal input of the
preamplifier to ground. This position also precharges the coupling capacitor to the DC
level of the input signal (see page 14).
The DC position couples both AC and DC components of the input signal.
oveR- Overrange Indicator. The OVERRANGE indicator lights red when the signal input
RANGE exceeds the selected range of the amplifier. If the indicator is on, the output signal is not
a true representation of the input signal(s). See page 14.
Gain Selector. The gain selectors set the gain of the preamplifier to X0.1, X1, X10, or
X100. If the oscilloscope does not display the correct volts per division for each gain
setting, refer to Table 2 on page 8.
Offset Controls. The ON/OFF switch activates the offset controls. The COARSE and
FINE controls provide a maximum of 40 volts offset in the X0.1 and X1 gain settings and
a maximum of 1 volt offset in X10 and X100 gain settings. See page 14.
ADA4OOA Instruction Manual