In
the
upward
position,
the
bias
of
V19
is
decreased,
resulting
in
increased
output
of V1
9
and
decreased
out
put
of
V18, thus
permitting
greater
undistorted upward
deflection.
These
conditions
are
reversed
when
the
de
flection
polarity
switch
is
in
the downward position.
The
6AG7 cathode
follower
V17
serves
primarily
as
an
impedance
transformer
so that
a
low
resistance po
tentiometer
can
be
used
as
a
gain
control.
It is neces
sary
that
the
potentiometer
have
a
low
value
so
that
stray
capacities
do
not
appreciably
vary
the
frequency
response
as
the
control
is
varied.
To
prevent
overload
ing
the
cathode
follower, the
VERT.
AMPL. ATTEN. has
a
stop
limiting its attenuation
to
a
maximum
of
2.
This
is
sufficient
to
cover
the
steps
of
the
INPUT
ATTENUA
TOR.
The
coupling
capacitor
C49
serves
to
remove
the
DC
component from
the
VERT.
AMPL. ATTEN.
so
that
the
image
does
not
jump
around
if
the
control
is
moved suddenly. Another
function
of
the
cathode fol
lower
is
to
permit
the
insertion of
a
delay
network
in
the
video
amplifier.
The
chassis
of
the
Type
511
A
is
drilled
to
permit
the insertion
of a
Tektronix
Type
1AD25
Delay
Network.
This
delays
the
signals
.25 microseconds
with
out
appreciable
distortion.
A
panel switch
permits
the
removal
of
the
delay
when
desired.
When
the
delay
network
is
factory installed,
the
oscilloscope
is
desig
nated
as
Type
511
AD.
When
the
INPUT CHAN.
SEL.
switch
is
in
the
2
STAGES
position,
the
6AG7
pre-amplifier
V16 is in the
circuit. This
stage
employs
the
same
compensation
system
as
the
output amplifier.
Variable
resistor
R99
controls
the
low
frequency
response,
and
L4
and
L5
the
high
frequency
response.
The
negative bias
from
the
voltage
divider
R90
and
R91
places
the
tube
on
the
correct
portion
of
its
operating
curve.
So
that the
screen
dissipation
will
not be
excessive,
the
screen
voltage
is
supplied
through
R95.
C45A
keeps
the
potential
rela
tively
constant
when
signals
are applied
to
the control
grid.
CALIBRATING
CIRCUITS
When
the
SIGNAL-CALIBRATE
switch is
put
in 'the
EXT.
CAL.
position, the
INPUT
ATTENUATOR
is
dis
connected
from
the
SIGNAL
INPUT
binding
post
and
connected
to
the
EXT.
CAL.
post.
The
positions
marked
X.
1
,
X
1
,
and
X10 connect
the
INPUT
ATTENUATOR
to
the
arm of the 5K
wire
wound
potentiometer
R76.
In
the
X
1
0
position the
high
side
of
R76
is
connected
via
S3
A
to
a
100
V
(peak
to peak)
winding
in
the
power
transformer.
The
X
1
and
X.1
voltages are
obtained
by
means
of
dropping
resistors
R74 and
R75
from the
6.3 V
winding.
The
arm
of
R76 is connected
to
the
CAL.
OUTPUT binding
post
so
that
the.
calibrating
voltage
may
be
measured
when
increased
accuracy
is
required.
CAUTION
—
THE
SCALES
OF
THE
CAL.
VOLTAGE
CONTROL
INDICATE
PEAK
TO
PEAK
VOLTS,
NOT
RMS.
MULTIPLY
RMS
BY
2.828
TO
CONVERT TO
PEAK
TO
PEAK.
POWER
SUPPLY
In
order
to
make
the
operation
of the
Type
511
A
independent
of
line
voltage variations
over
the
range
of 105
to
125
volts,
all DC
power
supplies are
electroni
cally regulated.
The
accelerating
potential
for
the
CRT
is
obtained from
an
oscillator
operating from the
regu
lated
+225
v.
supply.
A
single
transformer
supplies
all
of the
60 cycle
power.
The
principal
power
supply
provides
+
225
v.
at
approximately
250 ma.
Two
5V4G
tubes
are
used
as
rectifiers.
The
comparatively
low
voltage
drop of these
tubes
reduces
the
no
load
voltage to
which
the
input
capacitors
may
be
subjected.
A
large
input
capacitor,
80
mfd.,
reduces
the
ripple
to
about
12 volts.
The
elec
tronic
regulator
reduces
this
to
less
than
.1
volts.
This
circuit
consists
of
V27,
V28,
V29
and
their
associated
components.
To
see
how
this
circuit
works, consider
what
happens
when
the
output
voltage
at
the
cathode of
V27
increases
for any
reason.
The
cathode
of
V28
is
held
at
a
constant
potential
by
the type
5651
voltage
reference
tube
V29.
An
increase
of
voltage
at
the
cath
ode
of
V27
increases
the
grid
voltage
of V28,
thereby
decreasing
its
plate voltage
and consequently increas
ing
the
grid
bias
on
V27.
An
increase
in this
bias
increases
the
voltage
drop across
V27
and
thus
de
creases
the
output
voltage.
If
a
decrease
in
line
voltage
and
increase
in
load
current
tend
to
decrease
the
out
put
of the
regulator,
the
reverse
action
takes
place.
Thus
an
equilibrium is
reached
where
the regulated
output voltage
is
held
constant
within
very
narrow
limits.
To improve the action
of
the
regulator
for
ripple
or
sudden
changes
of
load,
the
capacitor C70
couples
the
grid
of
V28
directly
to the output. The
potentiometer
R159
allows
adjustment
of the
output voltage
to
225
volts
when
the tubes are
changed,
etc.
A
6X4 rectifier V24
with
its
cathode connected
to
one
side
of
the
high
voltage
winding,
supplies
a
negative
voltage
of
approximately
300 volts.
The
plates
of V24
are
tied
together
since
it
is
used
as
a
half
wave
recti
fier.
C68
is
used
as the input capacitor.
To
provide
regulation
and
additional
filtering,
the
gas filled
regu
lator
V30
is
used.
The
470
ohm
resistor
in
series
with
the
output
of
V30
eliminates a
tendency
of
V30
and
C21
(on
the
sweep
chassis) to
form
a
relaxation
oscillator.
The
+450
volts
necessary
to
operate
the
sweep ampli
fier is
obtained
from
the
full
wave
rectifier
V21
whose
output
voltage
is
added
to
the
output of
the main
recti
fier.
To
obtain
regulation and
filtering,
a
regulator
consisting
of V25 and V26 is used. This regulator oper
ates
in
the
same
manner
as the
+225
supply,
using
the
regulated
+225
as
reference
voltage.
Thus,
if
the
+225
is
not
set
ats
its
correct
value,
the
+450
volt
output
will
also
be in
error.
In order to provide
the
+
and
—
1500
volts
neces
sary
to operate
the
CRT,
an
oscillator
type
supply
is
used.
Since
the
input power
to
the
oscillator
comes
from
the
regulated
+225
volts,
its
output
is
not
affected
by
line voltage
changes.
The
oscillator
uses
the
6AQ5
tube
V31
in
a
conventional
Hartley
circuit.
A
high
volt
age
secondary
on
the
oscillator
transformer
supplies
approximately
1250 V
RMS
to
the
two
type
1B3GT/8016
rectifiers
V32
and
V33.
Filament voltages
for these
tubes
are
obtained
from
windings,
on
the
oscillator
trans
former.
Since
the
frequency of
the
oscillator
is
fairly
high (2
KC),
a
single
.05
capacitor
provides adequate
filtering
for
the
+1500 volts.
A
filter
consisting
of
a
.05
mf.
input
capacitor,
a
27K resistor, and
a
.5
mf.
output
capacitor
is
used
on
the —
1500
volt
supply
because
of
the
increased
load
and
need
for an
adequate
bypass
on
the
CRT cathode.
TYPE
511-A,
511-AD
SECTION
3, PAGE 4
Содержание 511A
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Страница 39: ...ALLIGATOR CLIP BANANA PLUG INSULATOR Fig 41 Input Probe disassembled SECTION 4 PAGE 21 TYPE 511 A 511 AD ...
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Страница 41: ...X Fig 43 Interior view left side SECTION 4 PAGE 23 TYPE 511 A 511 AD ...
Страница 42: ...E CI5E Fig 44 Sweep chassis bottom view R63 C2I TYPE 511 A 511 AD SECTION 4 PAGE 24 ...
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Страница 59: ...TRIGGER AMPLIFIER MULTIVIBRATOR SWEEP GENERATOR SWEEP MAGNIFIER SWEEP AMPLIFIER ...
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