Tektronix 2221 User Manual

Section
4— 2221
Operators
O
OPERATING CONSIDERATIONS
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GROUNDING
This section contains basic operating information and
techniques that should be
considered before
attempting to
make any measurements with the instrument .
GRATICULE
The most reliable signal measurements are made when
the oscilloscope and the unit under test are connected by
a common reference ( ground lead ) in addition to the signal
lead or probe . The probe's ground lead provides the best
grounding method for signal interconnection and ensures
the
maximum
amount
of
signal
-
lead
shielding in the
probe
cable . A separate ground lead can also be connected from
the unit
under test to
the
oscilloscope
GND
receptacle
located on
the
front
panel .
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The graticule is internally marked on the faceplate of
the crt to eliminate parallax - viewing errors and to enable
measurements ( see Figure 4-1 ) . The graticule is marked
with eight vertical and ten horizontal major divisions . In
addition , each major division is divided into five subdivi
sions . The
vertical
deflection factors and
horizontal timing
are calibrated to the graticule so that accurate measure
ments
can
be made
directly
from
the crt .
Also ,
percentage
marks for the measurement of rise and fall times are
located on the
left side
of the
graticule
.
SIGNAL CONNECTIONS
Probes
Generally , the accessory probes supplied with the
instrument provide the most convenient means of connect
ing a signal to the vertical inputs of the instrument . The
probe and probe lead are shielded to prevent pickup of
electromagnetic interference , and the 10X attenuation fac
tor of the probe offers a high input impedance that mini
mizes signal loading in the circuitry under test .
1ST OR LEFT
VERTICAL
GRATICULE
LINE
11TH OR RIGHT
VERTICAL
GRATICULE
LINE
Both the probe and the probe accessories should be
handled carefully at all times to prevent damage to them .
Avoid dropping the probe body . Striking a hard surface
can cause damage to both the probe body and the probe
tip .
Exercise care to prevent
the cable from
being crushed
or kinked . Do not place excessive strain on the cable by
pulling .
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RISE AND
FALL TIME
MEASUREMENT
PERCENTAGE
MARKERS
CENTER
VERTICAL
GRATICULE
LINE
CENTER
HORIZONTAL
GRATICULE
LINE
The
standard -
accessory probe is
a
compensated 10X
voltage divider . It is a resistive voltage divider for low fre
quencies and a capacitive voltage divider for high
frequency signal components . Inductance introduced by
long signal or ground leads forms a series - resonant circuit .
This circuit will affect system bandwidth and will
driven
by
a
signal
containing
significant
frequency
ponents at or near the circuit's resonant frequency . Oscil
lations
(
ringing
) can
then
appear
on
the
oscilloscope
waveform
display and
distort the true
signal waveshape .
Always
keep
both the
ground
lead and
the probe
signal
4207-09
Figure
4-1
.
Graticule
measurement
markings
.
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4-1

Tektronix 2221 Specifications

General

Brand	Tektronix
Model	2221
Category	Test Equipment
Language	English