RCA 6cw4 schematic

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AN-191
RCA
This 2CW4 vhf an
turret
data
Design
nuvistor cylindrical
base
which
used
nuvistor
television
experimental
tuner,
and
Features
The
wafers.
extend
as
6CW4
Note
practical
6CW4
design,
acti
the
external
and
in
VHF
describes
triodes
tuners.
neutralized
and
as
the
and
The
2CW4
RF
Television Tuners
high-frequency
their
performance
grid-drive
and a production-type
circuit
of
the
2CW4
featuring
ve
elements
Each
element
through
considerations
6CW4
are
high-mu,
extremely
is
the
ceramic
and
of
the
supported
connector,
Ampli'fiers
performance
application
of
amplifier
switch
2CW4
high-transconductance
small
tubes
are by a
base
as
wafer.
shown
these
tuner.
are
size
mounted
tripod
in
as
also
the
rf-amplifier
tubes
circuit,
Optimum
presented.
and
light coaxial! arrangement
One
lead
bottom
Triodes
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6CW4
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view
for
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shel1
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and
shield
of
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of
pin
the
which
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ground
unnecessary.
ELECTRON
RADIO CORPORATION
These
the
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TUBE
DIVISION
AMERICA,
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base
lugs
through
wafer
also
NOTE:
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serve
provide
the
socket,
PIN
I:
PLATE
PIN
z:
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PIN
PIN
PIN PIN PIN PIN
PIN
PIN 12: HEATER
INTERNAL CONNECTION.
TO
NOTE
3:
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4:
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GRID
&:
GRID
7:
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or,
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Re"iltered
R:egi,trod<l(t)
=====~=====
Several
design
used
with a high
transfer
important
in
these
transconductance-to-plate-current
characteristics
with a considerable
advantages
tubes.
in
reduction
40000
For
Fig.2.
of
are
example,
These
both
plate-input
inherent
high
transconductance
characteristics
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in
the
ratio,
and
heater-input
60
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70
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u
60
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50
U
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-'
40
~
<
30
20000
unique
as
shown
are
nuvistor
is
obtained
achieved
by
the
power.
Interelectrode
miniature
during
from
As a result,
larly
The
noise
tube
The
suitable
high
factor.
assembly
small
indicate
having
ments
equi
approximate
"
~
30000
I
"C.
-=-
w
U
~
20000
i;;
"
~
w
\'
et
10000
Fig.2 -Average
capacitances
triodes.
permits
to
tube,
tubes
size
for
o
In
especially
can
be
and
short
rf-amplifier
-3
characteristics
addition
a
high
with
replaced
lead
GRID
are
comparable
accurate
J
degree
respect
lengths
applications
transconductance-to-plate-current
In
that
val
these
en
t i
addition,
tubes
npu t capaci
the
input
short-circuit
have
higher
tance
resistance
-2
VOLTS
with
-\
for
element
of
uniformity
to
interelectrode
a minimum
of
the
ratio
input-impedance
input
and
resistance
transconduc
of a completely
15000~
o
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the
to
those
of
tubes
in
vhf
contributes
~
,
u
,
I
E
6CW4.
of
spacing
of
characteristics
circuit
make
television
than
tance.
neutralized
conventional
in
the
tubes
capacitances.
adjustment.
them
particu-
tuners.
to
low
measurements
other
These
tubes
measure-
triode
tube
- 2 -
====~
in
grid-drive
gain
input
where
at
vhf
resistance
!'
1S
R
IS
s
RL
IS
rp
1S
operation.
frequencies
results
the
amplification
the
source
the
load
the
plate
As
shown by
(impedance-matching
in
increased
Power
resistance
resistance,
resistance
G
aln
factor,
(matched
and
of
. _
the
following
losses
gain.
!,2RsRL
- 2
(rp+RL)
to
the
tube.
input
equation
neglected),
resistance),
for
power
increased
Neutralized
Fig.3 ing a 6CW4. 50-ohm bridge tuned
megacycle
admittance
shows
and
signal network
transformer-coupled
curves
susceptance
o~~s!
Grid-Drive
is a circuit diagram
In
this
generator
is
bandwidth.
was
varied
of
noise
for
used
this
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circuit,
and
for
For
determination
by
use
factor
circuit.
TYPE
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network
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and
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gain
1-75
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ve
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of
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noise
source
factor.
network.
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-=-
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50
fier
employ-
matched
capacitive-
a
double-
has a six-
source
Fig.4
conductance
to
a
Noise-factor
limited
indicated
duction used
power was
this arbitrary and signal readings the
of
was
A
substitution
method,
the
to
gain
Fig.] -Circuit
measurements
diode
by a
rf
calibrated
doubled.
reference
signal-generator
the
of
of
noise
detected
noise
the
original
the
the
signals
method
voltage
level.
signal
amplifier
AGe
diagram
amplifier
generator.
output
from
to
indicate
was
output
The
output
reference
generator,
directly.
Er·6.3V
of a neutralized
employing
were
made by The
signal,
the
noise
noise
used
for
of a signal
amplifier
was
attenuated
level.
which
- 3 -
the
6CW4.
use
of a coaxial
noise
was
factor
measurement
was
power
increased
generator.
generator
was
then
The
difference
calibrated
grid-drive
of
The
directly
placed
to
reduce
the
3 db by
noise
when
of
power
was
in
the
between
in
db,
temperature-
circuit,
the
intro-
generator
the
noise
gain.
set
to
Some
the
circuit,
amplified
the
dial
indicated
as
In
====~
Gs
(M~L1hH:lS)"
"-
-30
Fig.4(b)
power conductance
fier
gain
shown
~
SUSCEPTANCE
-Noise
as
for
in
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"-
-
20
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(a)
foctor
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ond
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of
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5
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of
amplifier
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factor
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shown
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S
as
for
Fig.3.
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a
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10
CON?UCTANCE
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20
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30
Turret
perimental
to-unbalanced
mixer
Tuner
Fig.S
tube
l~~t
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and
is
a
turret
transformer
serves
301l11,f
(30uul
Switch
circuit
tuner.
as
47000
OHMS
11
"
"
Tuner
the
1000
f"(
AGe
diagram
In
input
load
1000
j"1j(
this
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of
is
the
circuit,
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a
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section
matching,
Conventional
TO
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of
an
balanced-
and
tuner
OF
ex-
a
~OO-OH"
BALANCED
INPUT
Fig.5 -Circuit
of
diagram
an
experimental
of
- 4 -
the
turret
rf-amplifier
tuner.
sect
ton
~====
design over-all
Similar
using
shown to
improve
tectlniques
tuner
Channel
2
6
7
13
Table
a
6CW4.
in
Figs.
coupling
Channel
2
6 7
13
voltage-gain
I -
Noise-factor
turret
uata
are
The
3 and 5;
and
componAnts
performance
Noise
and
tuner
television-channel
shown
circuit
however,
on
employing a 6CW4
in
for
the
lower-frequency
Noise
Factor
(db)
3.9
4.0
5.3
5.5
gain
Table
the
Factor
(d
b)
5.
1
5.0
4.7
5.5
are
performance
11
this
load
used
tuner
throughout.
are
tabulated
Tuner
of
an
at
different
frequencies.
for a production-type
is
almost
on
the
tuned
channels
circui
.
Tuner
Noise
in
Table
Voltage
(
db)
47.9
Gain
45.3
45.0
44.0
experimental
switch
identical
ts
is
Voltage
(d
Gain
b)
45.0
43.5
44.5
45.0
factor
1.
tuner
to
those
increased
and
Table
A
50-ohm
input Both
amplifier method
the
ventional
was
tuner
average
Tube
Table
H
type
used
circuits
tube
outlined
miniature
Type
6BN4-A
6FH5 6ER5
6CW4
-
Noise-factor
switch
signal
for
gain
with
previously
performance
HI -Noise-factor
tuner
television-channel
generator
measurements
incorporated
a
to,OOO-ohm
types
conventional
television
and
was
of
in
Noise
gain
employing
equipped
a
grid
used
the
6CI4
the
same
Factor
(
db)
8.5
7.5
7.5
5.5
and
gain
miniature
tuner
performance
a
6CW4
frequencies.
with a balun
of
the
turret
dummy
to
at
if
resistor.
measure
at
channel
circuit.
comparison
triodes
channel
of a production-
at
different
to
match
tuner
stage
gain.
Again,
13
Tuner
consisting
Table
with
Voltage
(
38.0
41.0
41. 0
45.0
of
the
in
a
13.
and
the
db)
6CW4
to
the
swi
~ch
of
substitution
III
compares
that
of
Gain
with
tuner
tuner.
anif-
con-
General
The
voltages
Considerations
6CW4
for
and
best
2CW4
rf
are
designed
performance.
to
operate
Optimum
- 5 -
tuner
at
relatively
performance
low
is
plate
obtained
=====~=====
with a plate
of
noise
at
various
slightly
factor
across a 1000-ohm performance voltage be
drawn
plate
dissipation.
obtained
reduction
without
voltage
at
Under
teristic
available
the
operating
be
extended
shows
values
the
which
supply
values
tion,
maximum
Fig.8(a)
shows
from
maximum
bias
limits
condi
curves
of
value
provides
Use
so
for
curves
the
voltage
With
of
tions
which
of
voltages
plate
shows a circuit
agc
plate
the
voltage
B+
values
improves
is
Maximum
an
applied
these
conditions,
is
in
television
plate
by
the
of
supply
of
plate-voltage
the
the
that
maximum
example,
current,
of
plate circuit. dissipation
of
values
their
of
operation
in
and
tuner
applied
as
is
determined
the
application
determined
signal-to-noise
unsuitable
voltageof
addition
gain
reduction
voltage.
desired
6CW4
or
requires
does
dissipation
slightly
of
ID-percent
and
the
order
gain
resistor.
the
plate
as a balance
bias
of
the
in
receivers
of a plate-voltage
As
dropping
cutoff
ZCW4
careful
ratings
not
necessarily
but
can
configuration
With
the
(as
less
resistors
tolerances
wi
th
of
70
as a function
to
the
tuner.
At a
voltage
by
the
amount
of
positive
ratio
zero
volts.
6CW4
and
systems
are,
however,
these
tubes.
as a function
indicated,
resistor
characteristic.
with
a
series
choice
are
not
exceeded.
occur
shown
than
at
as a function
indicated
by
the
one
volt.
adjusted
the
high
heater
to
80
volts.
of
plate
The
B+
given
is
ZCW4
employing
level
reduced.
of
bias
between
at a given
of (The
plate
voltage.)
performance
have a sharp-cutoff
age.
considerably
As a result,
dropping
of
grid
the
circuit
or
series
dropping
of
tube-element
Maximum
occur
some
when
bias
value
using' a typical
of
bias
circuit
solid-line
to
either
to
simulate
and
B+
Fig.6
power
voltage
plate
current
plate
Supply
cutoff
resistor.
bias
designer
shunt
resistor
the
tube
other
6CW4.
voltage
and
voltage
curve)
the
the
vol
tages
shows
dissipation
is
dissipation,
limi t of
The
and
voltage
higher
can
for
different
determines
combination
operating
plate
is
than
Fig.8(b)
occurs
upper
worst
or probable
indi
curves
dropped
plate-
that
can
optimum
plate
charac-
voltages
than
easily
Fig.7
at
high
dissipa-
drawing
zero.
obtained
values,
at
lower
cated,
is
a
r
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Fig.6 -Voltage
factor power applied
as
for
functions
various
to
the
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0.7
gain
B+
turret
0.8
and
noise
of
input
voltages
tuner.
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of
grid-bias
values
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GRID
VOLTS
reduction
voltage
of
supply
as
a
for
voltage.
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function
different
=====~=====
47000
OHMS
Fig.
B(
a) -Typical
ration
of of wors t
the
Fig.8(b). slightly
choosing
of
condi
obtained
Under
potential gain-control
must
tube.
voltage signal
plate
age
probab
resultant
the
tions.
As
mentioned
these
be
levels.
40
using
bias
tube
A common
1000 18000
OHMS OHMS
,-'VI/'v-,----'\M~_oEbb
47000
OHMS
(a)
circui
the
6CW4
and
dissipation
voltage
le
condi t
maximum
In
this
above I volt.
values
when
depending
taken
through
of
from
they
conditions,
systems
to
as a function
under
ions
plate
case,
circuit
being
previously,
are
operated
on
generally
assure
method
a
large-value
t
configu-
(b) -curves
normal
0 f
operat
dissipation
maximum
The
equipment
components
exceeded
optimum
the
tube
the
grid
that
is
to
and
ion
.
plate
with
draws
impedance
present
a
low
return
resistor
10
....
,,'"
0.0
,.,.-
2
o.
o
is
dissipation
designer
which
under
performance
an
applied
current,
~ligh
grid
the
to
,.-
-1.0
shown
~ill
the
to
ground.
impedances
bias
agc
clamp
--
"-
GRID
occurs
has
prevent
worst
of
bias
and
voltage
terminal
the
,
"
'"
-2.0
BIAS
by
the
the
probable
the
of
is
grid
PLATE
CURVE
SUPPLY
VOLTS
--
--
"-
,
"
"
"-
~
VOLTS
(bl
dashed
at a bias
responsibility
maximum
6CW4
about
at
some
Because
to
ground,
is
applied
to a positive
voltage
HEATER
VOLTS
6.S
300
6.3
210
I
"
,
"
,
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curve
voltage
ratings
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and
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zero
volts.
negative
automatic-
to
at
\
-4.0
In
of
is
care
the
low
44
3.'
Fig.9
produced
factor
gain
to
drops
5.0
4.0
by
is
volts.
/
><
45
shows
reduction
only
only
",,-
!to 5.5
HEATER
the
slightly
about
NOISE
FACTOR
VOL
T5
variation
in
heater
affected
0.5
db
6.0
VOL
with
T
AGE IGAIN
6.'
of
voltage.
tuner
at
a
change
1
6
4
1.0
noise
reduced
Fig.9 -Vol
factor
volts
The
in
as
for
factor
curves
heater
heater
tage
gain
functions
the
turret
and
voltage
show
voltage,
voltage
and of
that
and
noise
heater
tuner
from
.
gaIn
noise
that
6.3
Information
and
reliable.
RCA
for
or
other
its
use.
otherwise
its
rights
furnished
However,
use;
No
license
under
of
nor
any
by
for
third
patent
RCA
is
no
responsibility
any
parties
is
granted
or
believed
infringements
which
by
patent
to
be
accurate
ia
tlssumed
of
may
result
implication
rights
patents
of
ReA.
by
from
or
"
I i
'11
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