LEVEL
control.
Thus
the
LEVEL
control
can
be
set
so
that
only
one
point
on
the
waveform
is
of
sufficient
amplitude
to
trip
the triggering
circuits.
This
point
can
be
located
by setting
the
controls
as
for
the
AC
or
DC
triggering
modes
and
then
moving
the
TRIGGERING
LEVEL
control
away
from
the
0
mark
in
either
direction
until
the trace
becomes
stable.
Trigger-Signal Source
For
most
normal
triggering
applications
the
1NT.
trigger
source is
most
convenient.
In
the
INT.
positions
of
the
TRIGGER
SELECTOR
switch
the
triggering
signal
is obtained
from
the
vertical
amplifier.
If
an
external
trigger
source
is available
it
is often convenient
to
use
the
EXT.
positions
of
the
TRIGGER
SELECTOR
switch.
An
external
trigger
source
is
particularly
useful
if
the
amplitude
of
the
signal
under
observation
is
changing
or
if
the probe
is
being
moved
from
point
to point
in a
circuit.
The
LINE positions
of
the
TRIGGER
SELECTOR
switch
permit
stable
triggering
at the
line
frequency.
These
positions
are
useful when
displaying almost
any
function
that
is
synchronized
with the
line.
TIME-BASE
OPERATION
General
The
time-base
generator
produces
the saw
tooth
waveform
which is used
to
move
the
beam
across
the
crt. The
TIME/CM
controls
vary
the
slope,
but
not
the
amplitude,
of
this
waveform,
and
thus
determine
the
sweep
rate
without
affecting the
length
greatly.
The
horizontal
amplifier
amplifies
the
saw
tooth waveform
and
applies
it
to
the
crt
deflection
plates.
The
HORIZ.
DISPLAY
switch
increases
the gain
of
the
amplifier five
times
in
the
MAG. position.
In
this
position
the
display
is
spread
over
the
equivalent
of
five
screen
diameters.
Sweep
Rate
The TIME/CM
controls
determine
the
sweep
rate
of
the
horizontal
trace.
The
TIME/CM
of
horizontal
deflection
is
indicated
by
the
black
numbers
when
the
HORIZ.
DISPLAY
switch
is
in
the
normal
position
and
by
the
blue
numbers
when it
is
in
the
MAG.
position.
These
numbers
are
correct
only
when
the
red
VARIABLE
control
is completely
clock
wise. The UNCALIBRATED
light
indicates
when
the
time
base
is
not
calibrated
for
this
reason.
The VARIABLE
control
has
a
range
of
about
2
1/2 to
1.
Magnifier
The
HORIZ.
DISPLAY
switch
increases
the
horizontal-amplifier
gain
five times in
the
MAG. position
expanding
the
time
base
so
that
the
center
one-fifth
of
the trace fills
the
graticule. The
MAG.
light
is
energized
when
the
HORIZ.
DISPLAY switch
is
turned
to
the
MAG. position.
Any
portion
of
the
trace may
be
positioned
on
the
screen
with
the
HORIZONTAL
POSITIONING
control.
If
the
VARIABLE
control
is fully
clockwise
the
magnified
sweep
rate
is
indicated
by
the
blue
numbers
at
the
TIME/CM
switch.
External
Horizontal Input
When
the
HORIZ.
DISPLAY
switch is
in
the
EXT.
position,
the
horizontal
amplifier
is con
nected
to
the
EXT. HORIZ.
INPUT binding
post.
The
STABILITY
control serves
as
an
attenuator
for
signals
applied
to
this binding
post.
VERTICAL-AMPLIFIER
OPERATION
Probes
The
P6000
probe
furnished
with this instru
ment
has
a
10-to-l
attenuation
ratio.
Be
sure
to
check
the
adjustment
of
the
probe
regularly
and
before
making
critical measurements.
If
the
compensation
is
incorrect
the
frequency
response
will
be
affected.
Touch
the
probe
tip
to the
calibrator
output
connector
and
display
several
cycles
of
the calibrator
wave
form.
If
the
top
and bottom
of
the
displayed
square wave
are
not
flat,
adjust
the
trimmer
capacitor
located
inside
the
probe
body
to
achieve
correct
square-wave
response.
Input
Connections
Be
careful
that
the
external
circuitry does
not
cause
deterioration
of
the
waveform
when
you
make
connections
to the
INPUT
connectors.
Improper termination
of
cables
may
cause
ring
AA
Operating
Instructions
-
Type
515/515A
2-9
