Operating Instructions; Features; Installation; General Operating Information - Tektronix 7A26 Instruction Manual

Section
1— 7A26
OPERATING INSTRUCTIONS
7A26
Features
The
7A26
Dual Trace Amplifier
plug-in unit
is
designed
for
use with
TEKTRONIX
7000-Series Oscilloscopes. The
7A26
is
a
dual-channel
wide-bandwidth
amplifier. Internal
gain and compensation
circuits are automatically switched
to
correspond
to
the
setting of
the
VOLTS/DIV
switch.
Channel
2 can be inverted
for differential
measurements.
PRELIMINARY INFORMATION
Installation
The
7A26
is
calibrated and ready
for use
as
received.
It
can be
installed
in
any
compartment
of
TEKTRONIX
7000-series oscilloscopes, but
is
intended
for principal use
in vertical
plug-in
compartments.
To
install,
align
the upper
and
lower
rails
of the
7A26
with the oscilloscope tracks and
fully insert
it.
The
front
will
be flush with the front of the
oscilloscope
when
the
7A26
is
fully inserted,
and
the
latch
at
the bottom-left
corner of the
7A26
will
be
in
place
against the front panel. See Fig. 1-2.
To
remove
the
7A26,
pull
on
the latch
(which
is
inscribed with
the unit identification
"7A26")
and
the
7A26
will
unlatch.
Continue
pulling
on
the
latch to slide
the
7A26
out of the oscilloscope.
GENERAL
OPERATING INFORMATION
Introduction
For
single-trace operation, either of the
two
identical
amplifier channels can be used independently by
setting
the
DISPLAY
MODE
and
TRIGGER SOURCE
switches
to
CH
1
or
CH
2 and connecting
the signal to
be observed to
the
appropriate input.
In
the discussions
to follow, single-trace
operations using
CH
1
only apply equally
to
CH
2 only.
Signal
Connections
In general,
probes offer the
most
convenient
means
of
connecting
a signal to
the input of the
7A26.
A
10X
attenuation probe
offers
a
high input
impedance and
allows
the circuit
under
test
to
perform very
close to
normal
operating conditions.
Any
TEKTRON
IX probe, with
a
readout coding
ring
can
be
used
with
TEKTRONIX
7A-series
amplifier
units
equipped
with readout.
The
readout coding
ring
on
the
probe connects
to
a
circuit
in
the amplifier unit which
automatically
corrects the
readout displayed on
the
CRT
to
the actual deflection factor
at
the
tip
of the probe being
used.
For probes
to be used with amplifier units with
or
without
readout,
see
the Tektronix,
Inc.
catalog.
Vertical
Gain
Check
and Adjustment
To
check
the gain of
either
channel,
set
the
VOLTS/DIV
switch
to
10
mV
and connect 40
millivolts,
1
kilohertz
signal
from
the oscilloscope calibrator
to
the input connec-
tor of
the channel being checked. The
vertical deflection
should
be exactly four
divisions.
If
not, adjust the
front-panel
GAIN
for exactly four
divisions of deflection.
The
GAIN
adjustment
is
engaged by
pressing
in
the
GAIN
control
knob and
turning the
knob
with
a
narrow-blade
screwdriver
(see
Fig.
1-3
Front
Panel
Controls and
Connectors).
Turn
the
knob
clockwise,
then
counter-
clockwise,
until
the
GAIN
control
is
engaged.
When
the
GAIN
control
is
engaged, the
vertical
deflection
will
change
as
the
knob
is
turned.
Turn
the
GAIN
control
knob
with
the screwdriver
until
the deflection
is
set
to exactly four
divisions,
then
remove
the screwdriver.
Input Coupling
The
Channel
1
and Channel
2
coupling
(AC-GND-DC)
switches allow
a
choice of input coupling
methods.
The
type
of display desired and
the applied
signal
will
determine
the
coupling
to use.
The
DC
coupling
position
must
be
used
to display the
DC
component
of the signal.
It
must
also be
used
to display
AC
signals
below about 30
hertz
(ten
hertz with
a
10X
probe)
and
square waves with low-frequency
components
as
these
signals are attenuated
in
the
AC
position.
Fig. 1-2. Release
latch.
RELEASE
LATCH
1-1