Tektronix 2337, Instruction Manual

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common reference (ground lead) in addition to the signal
lead or probe. The probe's ground lead provides the best
grounding method fo r signal interconnection and ensures
the maximum amount o f signal-lead shielding in the probe
cable. A separate ground lead can also be connected from
the unit under test to the oscilloscope GND connector
located on the rear panel.
SIGNAL CONNECTIONS
Probes
Generally, probes offe r the most convenient means o f
connecting an input signal to the instrument. They are
shielded to prevent pickup o f electromagnetic interference,
and the supplied 10X probe offers a high input impedance
that minimizes circuit loading. This allows the circuit under
test to operate w ith a minimum o f change from the normal
condition o f the circuit when measurements are being
made.
Coaxial Cables
Cables may also be used to connect signals to the input
connectors, but they may have considerable effect on the
accuracy o f a displayed waveform. To maintain the original
frequency characteristics o f an applied signal, only high-
quality, low-loss coaxial cables should be used. Coaxial
cables should be terminated at both ends in their char­
acteristic impedance. If this is not possible, use suitable
impedance-matching devices.
INPUT COUPLING CAPACITOR
PRECHARGING
When the input coupling switch is set to GND, the input
signal is connected to ground through the input coupling
capacitor in series w ith an 800-k£2 resistor to form a pre­
charging network. This network allows the input coupling
capacitor to charge to the average dc-voltage level o f the
signal applied to the probe. Thus, any large voltage
transients that may accidentally be generated w ill not be
applied to the amplifier input when input coupling is
switched from GND to AC. The precharging network also
provides a measure o f protection to the external circuitry
by reducing the current levels that can be drawn from the
external circuitry during capacitor charging.
The following procedure should be used whenever the
probe tip is connected to a signal source having a different
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2337 Operators
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