Connecting Input Signals; Grounding; Probes; Coaxial Cables - Tektronix 2247A Operator's Manual

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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 ( gr;;Qund lead) In
addition to the single lead or probe. The ground lead of the probe provld o
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 cod ed
probes are used.
OPERATING CONSIDERATIONS. To get the best waveform fidelity,
keep probe ground and signal leads as short as possible.
Mis adjusted probe compensation can cause measurem~nt error . Check
and adjust probe compensation whenever
d
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.
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2247 A Operators
Operators Familiarization
External Triggering
Any of the four vertical channels in the 224 7 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 0.5 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 ttie lin;iits of the 224 7 A specifications given in
Section 6.
Auto-setup action for each front-panel control 1st shown in Appendix A.
Min Setup
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MIN SETUP is only available on instruments Serial
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
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