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Operators Familiarization
.
Connecting Input Signals
Grounding
The most reliable signal measurements are made when the 224 7 A
and th
unit under test are connected by a common reference ( g,qund
lead) In
addition to the single lead or probe. The ground lead of the probe provld
the best grounding method for signal interconnection and ensures
th
maximum amount of signal-lead shielding in the probe cable. A
separate
ground lead (with a banana plug) can also be connected from the unit
under
test to the 224 7 A ground jack on the front panel.
Probes
A probe provides the most convenient way to connect an Input signal
to the
oscilloscope. The standard 1
OX
probes supplied with the 224 7 A are shielded
against electromagnetic Interference and have a high input impedance
for
low circuit loading. The subminiature probe bodies are designed for probing
circuitry with closely spaced leads.
SCALE FACTOR SWITCHING. The VOL TS/DIV scale factors, displayed
on the crt, reflect the probe attenuation factor when Tektronix
coded
probes are used.
OPERATING CONSIDERATIONS. To get the best waveform fidelity,
keep probe ground and signal leads as short as possible.
Mlsadjusted probe compensation can cause measurem~nt error. Check
and adjust probe compensation whenever a probe is moved to a different
channel or oscilloscope. For the probe compensation adjustment
pro-
cedure, see Section 4, "Operator Checks and Adjustments. "
For detailed operating considerations and probe maintenance, see
the
Instruction sheet supplied with the probe.
Coaxial Cables
Signal Input cable can greatly affect the accuracy of a displayed waveform.
To maintain original frequency characteristics of the input signal, use only
high-quality, low-loss coaxial cables. Coaxial cables must be terminated at
both ends In their characteristic Impedance to prevent signal reflections
within the cable. Use suitable Impedance-matching devices.
3-4
2247 A Operators
Operators Familiarization
External Triggering
Any of the four vertical channels in the 2247 A can be used as a source of A
and B trigger signals. When you need a trigger signal source different from
the one derived from displayed signals, you can use any free vertical Input
channel. CH 1 and CH 2 can
"condition"
a wide range of signals to produce
triggers over the full vertical deflection range from millivolts to hundreds of
volts. CH 3 and CH 4 have two basic attenuation factors ( 0. 1 and
O.
5 volts
per division), making them especially useful for triggering on and viewing
digital
signal levels.
Auto Setup
Pressing
the AUTO SETUP button automatically sets up the front-panel
controls
based on the characteristics of the applied signal. The voltage
amplitude, sweep settings, trigger parameters, vertical and horizontal
positioning,
and trace Intensities are preset to produce a usable waveform
display. The wav~form Is horizontally centered and vertically positioned
within the crt display. The voltage and frequency characteristics of the
Input
signal must
.
be within the lln;ilts of the 224 7 A specifications given In
Section
6.
Auto-setup
action for each front-panel control l!l shown In Appendix A.
Min Setup
-
J
•
MIN
SETUP
is
only
available
on
instruments
S@rial
Numbered
B020100 or above.
Pressing and
holding the Auto-Setup button until the instrument returns to
normal
operation
Initiates
the MIN SETUP function. This automatically sets
up the front-panel
controls but leaves many of the controls unchanged from
what the user
has set.
'
MIN SETUP
action for each front-panel control is shown in Appendix A.
MENU SYSTEM OPERATION
This subsection
provides operating details of the measurement menus,
service menus,
and Store/Recall Setup menus.
2247 A Operators
3-5
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