Tektronix 545A Instruction Manual page 23

Operating
Instructions
—
Type
545A
portion of the display
you
wish
to
expand
to
the center of
the graticule, then placing the
5X
MAGNIFIER
switch
in
the
ON
position.
When
the
5X
MAGNIFIER
switch
is
at
ON,
the
5X
MAGNIFIER
lamp
lights to
indicate the
mag-
nifier
is
on.
Any
portion of the original
unmagnified
display
can then be observed by
rotating the
HORIZONTAL
POSI-
TION
controls.
The sweep
magnifier can be
used with either
time
base
unit.
In
magnified
sweep
operation, the
sweep speed
indicated
by
the position of the
TIME/CM
control
is
divided by 5
to
obtain the actual time required
for
the spot
to
move one
centimeter. For
example,
if
the
TIME/CM
control
is
set at
5 MILLISEC, the actual time per centimeter
is
5 milliseconds
divided
by
5,
or
1
millisecond per centimeter.
The
actual
time per centimeter must
be
used for
all
measurements
of
time.
Amplitude
Calibrator
The amplitude calibrator provides
a
convenient source
of
square
waves
of
known
amplitude
at
a frequency
of
approximately
1
kc.
The square
waves
are used primarily
to adjust
probes
and
to verify the calibration of the
vertical-deflection
system
of
the
oscilloscope
and
plug-in
unit.
Calibrator
square-waves are adjustable from
.2 milli-
volts,
peak-to-peak,
to
100
volts,
peak-to-peak,
in
18
steps.
The amplitude
is
controlled
by
the setting of the
AMPLITUDE
CALIBRATOR
switch
and
is
accurate
within
3%
of
the
AMPLITUDE CALIBRATOR
switch
setting
when
the output
is
connected
to
a
high
impedance
load.
Dual-Trace Displays
The Type
CA
Plug-In Unit allows you
to obtain
two
separate
traces
on
the face
of the
crt.
This permits
you
to
display
two
functions simultaneously. Detailed
instructions
for
operating
the
Type
CA
Unit
in
conjunction with the
Type 545A
Oscilloscope are
contained
in
the
Instruction
Manual
for the
Type
CA
Unit.
When
you are using the
Type
CA
Unit
in
the
chopped
mode
to obtain a dual-trace presentation, switching
tran-
sients
will
be
displayed
on
the screen.
You
can
eliminate
these switching transients
by
placing the
CRT
CATHODE
SELECTOR
switch
on
the rear of the instrument
in
the
DUAL-
TRACE
CHOPPED BLANKING
position.
Intensity
Modulation
The
crt
display of the
Type 545A
Oscilloscope can be
intensity
modulated by an
external signal to display addi-
tional information. This
is
done
by
disconnecting the
grounding
bar
from
the
EXTERNAL CRT
CATHODE
con
nector at the rear of the instrument
and
connecting
the
external signal to
this
terminal.
The
CRT
CATHODE
SELEC-
TOR
switch must
be
in
the
EXTERNAL CRT
CATHODE
posi-
tion.
When
you
wish
to
make
very accurate time measure-
ments from
the
crt
display,
you can
intensity
modulate
the
beam
with time markers
and make
your
measurements
di-
rectly
from
the time
markers presented on
the screen.
A
positive
signal of
approximately 25
volts
is
required
to
cut off the
beam
from normal
intensity.
®1
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