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Operating Instructions—
7A15A/7A15AN
BASIC
OPERATION
General. This
procedure demonstrates
the use of the
connectors and
controls
of the
7A15A/7A15AN,
while
at
the
same
time providing
a
means
of
checking
the
basic
operation
of the
instrument.
Preliminary Setup.
Install
the
7A15A/7A15AN
into
any
7000-series oscilloscope
vertical
compartment and
set
the
oscilloscope
VERTICAL
MODE
and
TRIGGER SOURCE
to
the
proper
settings.
Install
a
7-series
time-base
unit
into
a
horizontal
compartment
and
set
the
oscilloscope
HORIZONTAL
MODE
to
the
proper
setting.
Set the
time base
unit to a
sweep
rate
of
one
millisecond
per division
and
set
the
triggering
mode
to
AUTO.
Procedure
1.
Set
the
7A15A/7A15AN AC-GND-DC
switch
to
GND
and
position the
trace
to the center
of the graticule.
2.
Set the
VOLTS/DIV
switch
to
10
mV
and
apply
a
40
mV
1
kHz
square-wave
signal
from
the oscilloscope
CALI-
BRATOR
to the
7A15A/7A1
5AN
INPUT
connector.
Set
the
AC-GND-DC
switch
to
DC
and check
for
a
four
division
display.
3.
Set
POLARITY
switch
to
INVERT
and check
that
the displayed
signal
is
inverted
as
compared
to
its
appear-
ance
in
step
2.
4.
Set the
AC-GND-DC
switch
to
AC
and check
that the
trace
is
centered
on
the
CRT
graticule.
5.
Set the oscilloscope
CALIBRATOR
to
4
mV
and
the
7A15A/7A15AN
MAG
switch
to
X10. Check
for
a
four-
division display.
6.
(7A15A
Only)
Press the
7A15A IDENTIFY
button,
check
that
the display
moves upward
approximately
0.3
division
and
the
readout
(if
so
equipped)
reads
"IDENTIFY".
GENERAL
OPERATING INFORMATION
Signal
Connections
In general,
probes
offer the
most
convenient
means
of
connecting
a
signal
to the
input of the
7A15A/7A15AN.
A
10X
attenuator
probe
offers
a
high
impedance and
allows
the
circuit
under
test
to
perform
very
close to
normal
operating conditions.
The
Tektronix
P6053
probe
is
equipped
with
a
readout
coding
ring
which connects
to
a
circuit
in
the amplifier
unit.
This automatically
corrects the
readout displayed
on
the
CRT
to the
actual deflection factor
at
the
tip
of the
probe. This
probe
is
recommended
for
use
with
the
7A15A
and an
oscilloscope
equipped with
readout.
The
Tektronix
P6054
probe
is
electrically identical
to the
P6053
but
is
intended
for
use with
systems
not
equipped
with readout.
For
more
information
refer
to the
Tektronix
Inc.
catalog.
Vertical
Gain
Check
and Adjustment
To
check
the
gain of
the
7A15A/7A15AN,
set
the
VOLTS/DIV
switch
to
10
mV
and connect
a
40
mV.
1
kHz
signal
from
the oscilloscope
calibrator to the
Input connec-
tor.
The
vertical
deflection
should be exactly four
divisions.
If
not. adjust the front
panel
GAIN
for
exactly four
divi-
sions.
Input Coupling
The
AC-GND DC
switch allows
a
choice
of
input
coup
ling
methods.
The
type
of display desired
and
the applied
signal will
determine
the
coupling
to use.
The
DC
coupling
position
can be used
for
most
applica-
tions.
For
AC
signals
with frequencies
below about 30
Hz
(10
Hz
with
a
10X
probe),
and
square
waves
whose
low-
frequency
components
are
important
to the display,
it
is
necessary
to
use
DC
coupling
to
obtain
a
satisfactory
presentation.
In
the
AC
coupling
position the
DC
component
of the
signal
is
blocked
by
a
capacitor
in
the
input
circuit.
The
AC
coupling
position provides the best display of
signals
with
a
DC
component
much
larger
than the
AC
component. The
pre-charge feature
should be used
when
there
is
a
possibility
of
having
a residual
charge
on
the input capacitor of the
opposite
polarity
to
the
intended
input,
and
when
the
algebraic
sum
of the
combination
of
charges
may
be
greater
than
the
maximum
input
limitations of the amplifier.
To
use
this
feature,
first
set
the
coupling
switch
to
GND,
then
connect
the
probe
to
the
circuit
and
wait
about
two
seconds
for
the
coupling
capacitor
to
charge,
set
the
coupling switch
to
AC.
The
GND
position provides a
ground
reference
at
the
input of the
amplifier
without
externally
grounding
the
Input connectors.
However,
the
signal
connected
to the
input
is
not grounded, and
the
same
DC
load
is
presented
to
the
signal
source.
22
REV.
B.
OCT.
1974
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