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GATE
voltages
available
at
the
front
panel
binding
posts.
The
duration
of
the
time
V5
is
cut
off
is
deter
mined
by
the
time
constant
of
C7,
R20C,
R20C1
thru
R20C9 (depending
upon
the position
of
S10A),
and
the
voltage
applied
across
the
circuit
and
is
substantially
independent
of
the
characteristics
of
the
trigger
im
pulse.
To
cover
a
range
of
sweep
time
from
.1
sec.
to
1 microsecond,
C7
has
five values
as
selected
by
the
SWEEP
RANGE
switch.
The
calibrated
variable
resistor
R20C
is
returned
to
+225
volts.
This
makes
possible
the
use
of
a
larger
value
of
C7
than
would
otherwise be
possible, thus
reducing
the
voltage
divider
action
of
the
stray
capacitances
to
ground in
the
grid
circuit
of
V5.
Variation
of
R20C,
R20C1-9,
in
conjunction
with
the
five
values of
C7
gives
a
continuously
variable
adjustment
of
multivibrator
pulse
length.
Unblanking
Circuit
During
the
waiting
period
the
bias
on
the
cathode
ray
tube
is
such
that it is
completely
cut off.
As soon
as
a
trigger
appears
and
the
sweep
starts,
it
is
necessary to
provide
a
positive pulse
on
the grid
of
the
cathode
ray
tube
and
thus
turn on
the
electron
beam.
This
pulse
should
have
an extremely
fast
rise
and
a very
flat
top
so
that
the
brightness
of
the
image is
uniform.
To
secure a
pulse of
this
nature,
the
negative
pulse
from
the
grid
of
V5
is
limited
by plate
current cutoff
in
V7.1A
before
it
reaches
full amplitude.
The
voltage
divider
R37,
R38
sets
the
d.c.
bias
on
the
grid
of
V7.1A
at
approximately
0
volts
and
supplies
a
negative
pulse
of
45
volts amplitude.
Cl
2
insures
that
the
leading
edge
will
be
coupled
thru
without
loss
of
rise
time
due
to
grid
and
wiring
capacities
to
ground.
The
45
volt
negative
pulse
is
more
than
adequate
to
drive
V7.1A
into
cutoff,
thus
producing at
the
plate
a
square,
flat
topped
posi
tive
pulse having
an
amplitude
of
80
volts.
To
provide
increased
rise
time,
L2.1
is
employed
in
the
plate
circuit
of
V7.1A.
The
cathode follower V7.1B
serves
to
isolate
the
plate
circuit
of
V7.1A
from
the
capacity to
ground
of
the
cathode
ray
tube
grid
and
associated
wiring,
thus
preventing
any
appreciable
reduction
in
rise
time
due
to
their
effect.
This
circuit
is
capable of
unblanking
the
tube
in
less
than
.1
microsecond after a
sharp
trigger
pulse
reaches
the
TRIGGER
INPUT
binding post.
Gate
Output
Generator
V8
serves
to
isolate
the
gate
output
binding
posts
from
the
multivibrator.
It
receives
a
positive
pulse on its
grid
of
the same
duration
as
the
sweep
from the
plate of
V5
via the voltage
divider
R32
and
R33.
C
10
maintains the
steep
sides
of
the
pulse.
Since
the
plate
and
cathode
load
resistors
are
equal,
pulses
of
equal
size
but
oppo
site
polarity
appear
at
the
plate and cathode. The
+gate
from
the
cathode
has no
blocking
capacitor
and
therefore
preserves
the
square
pulse
for
the
longest
sweeps.
It
was
not
felt
desirable
to
have
the
—
Gate
binding
post carry the
+225
V potential
of the
plate;
therefore
a
blocking
capacitor
is
used.
Sweep
Generator
The
sweep
generator
circuit
produces
the
basic
wave
necessary
to
sweep the
beam
linearly
across
the
tube
and
return it
to
its
starting
point.
During
the
waiting
period
the 6AG7
tube
V9
is
held
fully
conducting
since
it
has
no
bias
and
therefore
its
plate
is
about
at
ground
potential.
When
a
trigger
occurs
the
negative pulse
from
the
multivibrator
cuts
the
grid
of
V9
off
very
rapidly.
The
plate
therefore
rises
in exponential
fashion
at
a
rate
depending
upon
R20D,
R20D1-9
(as
determined
by
setting
of
S10B),
R39,
the
voltage
applied
across
the
circuit,
and
Cl5.
When
the
multivibrator
pulse
ends
V9
conducts
again,
thus
discharging
C1
5.
Since
C1
5
is
charged to
only
about
5%
of
the
supply
voltage
the
rate
of
rise
is
very
nearly
linear.
Five
values
of C1
5
as
determined
by
the
SWEEP
RANGE
switch
in combina
tion
with
the
variable
resistors R20D
and
R20D1-9
pro
vide
a
continuous
variation
of sweep
speed of
from .1
sec.
to 1 microsecond
for
a
10
cm
sweep.
In
order
to
maintain
the
correct
multivibrator pulse
length
as the
sweep
speed
is
increased,
the
SWEEP
RANGE
switch
changes
C7
in
the
multivibrator
and
C
15
simultaneous
ly.
In a
like
manner
the
SWEEP
SPEED
MULT,
controls
are
dual controls changing
R20C,
R20D
and
R20C1-9,
R20D1-9
simultaneously. In
order
to
maintain
the
cali
bration
of
the
SWEEP
SPEED
MULT,
dials
when
tubes
are
changed,
etc.,
the voltage
applied
to
R20D
may
be
varied
by
R42
which
sets
the
grid
potential
of
the
cath
ode
follower
VI
5.
The
use
of
the
cathode
follower
in
stead
of
a
potentiometer
maintains
a
constant
charging
potential
as
R20D,
R20D1-9
is
varied.
Details
of this
adjustment
may
be found
in
Section
IV.
The
two
resistors
R39.
11
and
R39.12
connected in
series
are
shunted
across
R20D1-9
to
compensate
for the
plate
circuit
loads
of
V9.
Sweep
Output Cathode Follower
To
provide the
necessary
isolation between
capaci
ties
fastened
to
the
SWEEP
OUTPUT
binding
post and
the
sweep
generator,
the
cathode
follower
V
1
0
is
pro
vided.
The
grid
of
V
1
0
is
connected
to
the
plate
of
the
sweep
generator.
The
SWEEP
OUTPUT
binding
post
is
connected
to
the
cathode
of
V10
without
a
blocking
capacitor.
Sweep
Magnifier
The
function
of
this
circuit
is
to
delay the
start
of
the
sweep
for a
variable
time,
and
then cause
it
to
go
at
five
times
its
normal
speed. This is
accomplished
by
the
biased
cathode
coupled
amplifier
V11
.
In
this
type
of amplifier a
positive
change
in
the grid
potential
of
V
11A raises both cathodes
and
therefore
corresponds
to
a
negative
change
on
the
grid
of
V11B.
Thus
the
plate
of
V
11
gives
an amplified
version
of
the
signal
on
the
grid
of
V11A,
without
change of
polarity.
The
SWEEP
MAGNIFIER
POSITION
potentiometer
raises
the poten
tial
on
the
grid
of
V
11
B
above
ground
and
thus
the
cath
ode potential of V
11
A.
No
sweep
appears
on
the
plate
of
V
11B
until
the
plate
of
the
sweep
generator
overcomes
this
bias,
then
the
amplified
sweep
appears.
Sufficient
bias
is available
on
the
SWEEP
MAGNIFIER
POSITION
to
make
it
possible
to
start
the
magnified
sweep
at
any
point
on
the
normal
sweep. V6
is employed
as
a
DC
restorer
to
insure
that
the
magnified
sweep
will
start
at
the
same
potential
each time,
thus
preventing
jitter
or
instability
of
the
trace.
When
the
magnified sweep
is
not
desired,
the
SWEEP
MAGNIFIER POSITION
knob
TYPE
511-A, 51
1-AD
SECTION
3,
PAGE
2
Summary of Contents for 511A-AD
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Page 13: ...2 7 0 180 120 6 0 DEGREES OF PHASE SHIFT FREQUENCY TEKTRONIX JNC 12 28 50 ...
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Page 41: ...Fig 41 Input Probe disassembled SECTION 4 PAGE 21 TYPE 511 A 511 AD ...
Page 42: ...Fig 42 Interior view right front side TYPE 511 A 511 AD SECTION 4 PAGE 22 ...
Page 43: ...Fig 43 Interior view left side SECTION 4 PAGE 23 TYPE 511 A 511 AD ...
Page 44: ...TYPE 511 A 511 AD SECTION 4 PAGE 24 ...
Page 45: ...Tf S 4 t C15C C15D ...
Page 46: ...R30 1 SECTION 4 PAGE 25 TYPE 511 A 511 AD ...
Page 48: ...SECTION 4 PAGE 27 TYPE 511 A 511 AD ...
Page 50: ...SECTION 4 PAGE 29 TYPE 511 A 511 AD L24 ...
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Page 62: ...EXT BLOCK DIAGRAM OF TYPE 5IIA CATHODE RAY OSCILLOSCOPE 7 13 51 ...
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Page 64: ...SWEEP MAGNIFIER SWEEP AMPLIFIER ...
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