Tektronix 515 Instruction Manual page 10

TIME/CM
VERTICAL
POSITIONING
HORIZONTAL
POSITIONING
CALIBRATOR
.5
MILLISEC
Center
Center
10
Connect
a
lead
from
the
CAL,
OUT
con-
nector
to
the
INPUT
1
connector.
If
the tubes
have had time
to
warm
up, turn the
INTENSITY
control
clockwise
until
a
trace
is
visible
on
the screen. Adjust
the
FOCUS,
ASTIGMATISM
and
INTENSITY
controls
to
produce
a
sharp
trace
of
comfortable brightness.
The two
POSITIONING
controls will
move
the trace vertically
and
horizontally as
nec-
essary
to
position the display
where you want
it
on
the crt
screen.
Triggering
Modes
If
you have
not
had previous experience
with
the
type
of
trigger controls
used on
this
oscilloscope, the calibrator
waveform
is
a
good one
to
practice
with.
A
few minutes
spent on trying
the
triggering
modes described
below
will
be time well spent
in
terms
of
future operating convenience.
Auto
The
triggering
method
used
in
the
preceeding
example
is
the
AUTO,
(automatic)
mode
of
operation.
It
is
the
simplest
mode
of triggering.
There
are no front-panel controls
to
be adjusted
when
using
this
mode.
If
the signal
is
removed
from
the input
connector, the
sweep
will
con-
tinue, but
at
a
reduced repetition rate.
This
provides
a visual indication that
the signal
has been
removed and
the
sweep
and triggering
circuits
are
operating.
AC
Now
try the
AC mode
of triggering.
Turn
the
red
TRIGGER SELECTOR
knob
to
AC.
Advance
the
TRIGGERING
LEVEL
control
clockwise
until
you get a stable trace.
There
may
be
a
considerable range
over which you
get a
stable trace.
The
start of the trace
will
move
up and
down
the
edge
of the
square
wave
over
this
range. Notice that
the trace
starts
on
the
up-going
part of
the calibrator
square wave.
Now
turn the black
TRIGGER SELECTOR
switch
to the
-INT
position
and
readjust the
TRIGGERING
LEVEL
control
to
get a stable
trace
again.
Notice
now
that
the trace starts
on
the
down
-going portion of the
square
wave
and
that
the position of the start
can again
be changed
somewhat
with the level control.
DC
Turn
the red
TRIGGER
SELECTOR
knob
to
DC,
If
necessary adjust the
TRIGGERING
LEVEL
control for stable triggering.
Move
the
trace vertically
on
the
screen
with the
VERTICAL
POSITIONING
control
and note
that
triggering
occurs
at
a vertical level
on the
screen selected by
the
LEVEL
control,
and
that
the triggering point
changes
relative
to
the
waveform
as the
waveform
is
positioned
vertically.
This
effect will
be
more
noticeable
if
you look
at
a
low-frequency sine
wave.
H
F
Sync
The H F
SYNC
position of
the
TRIGGERING
SELECTOR
switch
is
primarily
for
signals
having
a
repetition rate
in
excess of five
megacycles.
In
this
position the
time base
will
trigger poorly,
if
at
all,
on
the calibrator
waveform.
To
stabilize the display of a
high-
frequency signal,
simply advance
the
STABILITY
control
clockwise
until a
stable trace
is
obtained.
The
LEVEL
control
is
not
used
in
the
H
F
SYNC
mode.
FUNCTIONS OF CONTROLS
AND
CONNECTORS
CRT
Control
s
FOCUS
Control
to
adjust the
beam
for
maximum
sharpness
of
the trace.
INTENSITY
Control
to
vary the brightness
of
the trace.
2-2 Operating Instructions
-
Type 515/515A
AA