National NC-2-40D User manual
for
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tommvmtznian
A
high
performance
receiver
of
advanced
design
for
the
490
to
30000
kilocycle
range
HIGHLIGHTS...
•
490
to
30,000
kilocycle
Range
• 6
General
Coverage
Ranges
• 5
Amateur
Bands
with
Uniform
Bandspread
•
All
Ranges
Have
Definite,
Accurate
Calibration
•
Actual
Single
Dial
Control
•
Temperature
Compensation
•
Automatic
Voltage
Stabilization
•
Series
Valve
Noise
Limiter
•
New,
Flexible
Crystal
Filter
•
115
and
230
Volt,
50/60
Cycle
Operation
•
New,
Stabilized
S-
Meter
Circuit
•
Speaker
in
Matching
Cabinet
•
Phonograph
Or
High
Level
Microphone
Pick-up
Jack
National
Conapany,
Inc.
THE
NC-
2-40D
COMMUISTICATION
RECEIVER
NEI
TIIIN
I.
DEN.
IIIPTION
I-1.
General
The
NC-
2-40D
RADIO
RECEIVER
is
a
twelve
tube
superheterodyne
covering
the
continuous
frequency
range
from
490
to
30,000
kilocycles.
This
receiver
was
de-
signed
to
give
the
amateur
a
maximum
of
bandspreading,
and
combines
mechanical
bandspreading
on
all
bands
with
additional
electrical
bandspreading
of
the
10,
11,
20,
40,
and
80
meter
amateur
bands.
The
NC-
2-40D
Receiver
also
incorporates
very
stable
high
frequency
circuits, due
to
the
high
frequency
oscillator
circuit
design
developed
in
the
National
Laboratories,
which eliminates
the
exasperating
detuning
effect
of
the
R.F.
Gain
control,
and
the
even
more
undesirable
motor-
boating
or
fluttering
which
occurs
in
most
receivers
when
tuning
in
strong
high
frequency
sig-
nals.
Perhaps
the
best way
to
prove
the
exceptional
performance
of
this
type
of
circuit
is
in
the
10
meter
band
where
a
line
voltage
shift
from
100
to
120
volts
produces
less than
1000
cycles change
in
tuning.
This
is
a
variation
of
less than
.003
percent.
Frequency drift
has
been
re-
duced
to
a
minimum
through
use of
tempera-
ture
compensating
capacitors
not
only
in
the
high
frequency
oscillator
circuits,
but
in
the
R.F.
and
first
detector
circuits
as
well.
The
sensitivity
of
the
NC-
2-40D
is
particularly
high,
an
input
signal
of
only
1
microvolt providing
1
watt
of
audio
out-
put. R.F.
coupling
circuits
developed
in
the
National
Laboratories
have
made possi-
ble
the
maintenance
of
full
sensitivity
up
to
the
highest
frequencies
covered
by
the
receiver.
Moulded
polystyrene
coil
forms
are
used
in all
circuits,
both
R.F.
and
I.F.,
thus
assuring
the
freedom
from
cir-
cuit
losses
or
detuning
which might
other-
wise
be
caused
by
humidity
effects.
Vari-
able
condenser
insulators,
tube
sockets,
etc.,
are of
Isolantite.
The
chassis
of
the
NC-
2-40D
is
cadmium
plated
to
provide
positive
grounds
and
better
conductivity
as
well
as
a
neater
appearance.
Components
in
the
NC-
2-40D
are
treated
as
necessary
with
a
fungus-
resistant
varnish
for
an
added
protection
against
any
damage
which
may
re-
sult
from
humidity
or
temperature.
Each
equipment
consists
of
a
receiver
and
speaker
built
for
either
relay
rack
or
table
mounting
and
an
instruction
manual.
The
standard
NC-
2-40D
Receiver
is
de-
signed
for
operation
from
a
110/120
volt,
or
220/240
volt
50/60
cycle
power
source.
1-
2.
Circuit
The
circuit
employed
on
all
bands
con-
sists of
one
stage
of
radio
frequency
am-
plification,
a
separate
first
detector
and
stabilized
high
frequency
oscillator,
two
intermediate
frequency
stages,
an
infinite
impedance
second
detector,
a
self-
balancing
phase
inverter
and
audio
amplifier,
and
a
push-pull
audio
output
stage.
The second
detector utilizes
one
set
of
elements
of
a
dual
triode;
the
other
set
of
elements
is
utilized
for
a
series
valve
noise
limiter.
Separate
tubes
are
used
in
the
automatic
volume
control
and
beat
fre-
quency
oscillator
circuits.
The latter
is
coupled
to
the
second
detector
for
C.W.
re-
ception.
A
crystal
filter
is
connected
between
the
first
detector
and
first
I.F.
amplifier
tubes.
All
voltages
required
by
the
receiver
circuits
are
supplied
by
a
built-in
power
supply.
1-
3.
Tube
Complement
The
NC-
2-40P
is
supplied complete with
tubes
which
are
tested
in
the
receiver
at
the
time of
alignment.
The
tubes
employed
are
as
follows:
R.F.
Amplifier
6SK7
First
Detector.
6K8
H.F.
Oscillator
6J5
First
I.F.
Amplifier
6K7
Second
I.F.
Amplifier
6SK7
Second
Detector-
Limiter
6SL7GI/O
Automatic
Volume
Control
6V6
Beat
Frequency
Oscillator.
6SJ7
Amplifier &
Phase
Inverter...6SN7C1/G
Push-
Pull
Audio
Output (
2)
6V6
Rectifier
5Y3G
9
1-1.
Tuning System
The
master
tuning
capacitor
C-1 and
six
sets
of
coils
are
used
to
tune
the
490
to
30,000
kilocycle
range
of
the
receiver.
By
means
of
a
highly
developed
band
change
mechanism,
four
of
these
same
coil
sets
are
made
to
spread
the
10, 11,
20,
40,
and
80
meter
amateur
bands
uniformly
over
the
major
portion
of
the
tuning
dial (
HRO
System).
All ten
ranges
are
calibrated.
All
transformer
coils
of
the
R.F.
am-
plifier,
first
detector
and
H.F.
oscillator
stages
with
their
associated
padder
and
air-
dielectric
trimmer
capacitors
are
mounted
in
a
redesigned
rigid
aluminum
casting
which slides
the
length
of
the
chassis,
being moved
by the
MAIN
TUN-
ING
control.
The
various
coil
assemblies
are
fitted
with
heavy
contact
pins
which
engage
spring
contactors
mounted
immediate-
ly
under
the
variable
tuning
capacitor.
This
system
permits
thorough
shielding
of
each
individual
coil
while,
at
the
same
time,
the
coils
in
use
are
moved
to
the
best
position
in the
chassis,
giving
short-
est
leads
to
the
tubes
and
master
tuning
capacitor,
and
all
other
coils
are
com-
pletely
disconnected
from
the
circuit.
1-
s.
Crustal
Filter
Undoubtedly,
the
most
efficient,
flex-
ible
crystal
filter
yet
designed
is
used
in
the
NC-
2-40D
Receiver.
Six
uniform
steps
of
selectivity,
as
shown
in
Dwg.
No.
1,
and
a
variable
phasing
control
allow
the
re-
ceiver
to
be
adjusted
to
almost
any
operat-
ing
condition,
a
highly
desirable
feature
for
both
short
wave
communication
and
broadcast
reception.
The
curves
show
that
any
degree
of
selectivity
between
that
of
full
single
signal
operation
and
wide
band
broadcast
reception
is
available,
the
ratio
between
the
two
being
almost
forty
to
one.
1-
6.
Noise
Limiter
The
noise
limiter
of
the
NC-
2-40D
Re-
ceiver
is
of
the
series
valve
type
devel-
oped
in
the
National
Laboratories.
Its
ef-
fectiveness
and
superior
performance
as
compared
to
the
more
common
types
of "
si-
lencers"
were
proved
in
the
modernized
NC-
200
receivers.
A
threshold
control
on
the
front panel
permits
adjustment
of
the
level
at
which
limiting
action
starts.
THE
NC-
240D
HU:CFI\
ER
1-7.
Toi
e
(
Metro!
The
tone
control
is
used
to
vary
the
frequency
characteristic
of
the
audio
am-
plifier.
The
control
is
particularly
help-
ful
when
receiving
weak
signals through
in-
terference,
as
explained
in
Section
3.
I-
8.
Signal
Strength
Meter
A 0
to
1
milliammeter,
serving
as
a
signal
strength
meter,
is
front panel
mounted.
It is
fitted
with
a
scale
gradu-
ated
in
S-
units
from
1
to
9
and
in
db
above
S-9
from
0
to
40
db.
The
circuit,
in
which
the
meter
is
connected,
makes
possible
ac-
curate
signal
input
readings
from
below
1
microvolt
to
1,000
microvolts.
1-
9. :
1 '
sienna
Input
Antenna
input
terminals
are
located
at
the
rear
of
the
receiver
chassis
near
the
center.
The
input
circuit
is
suitable
for use
with
a
single
wire
antenna,
a
bal-
anced
feed-
line
or
a
low
impedance
concen-
tric
transmission
line.
Average
input
im-
pedance
is
500
ohms.
lo'
ice
10
OFr
-
12
10
8 6 4 2 0 2 4 6 8
tO
2
4-
2
PHASING
NOTCH
4 5
ADJUSTABLE
ON
SWITCH
POS
I 5
INCLUSIVE
KC
OFF
RESONANCE
4 3 2
OFF
MAX
SELECTIVITY
-
200
CYCLES
TOTAL
Mpg.
No.
1.
Typical
Selectivity
Characteristics
THE
W-2-101)
RECE1\
-
FR
I-
HL
Audio
Output
Two
audio
output
circuits
are
provid-
ed:
(1)
A
headphone
jack
is
mounted
on
the
front
panel
and
is
wired
so
as to
silence
the
loud-
speaker
when
the
phone
plug
is
in-
serted.
The
correct
load
impedance
for
the
headphone output
is
20,000
ohms,
this
being
the
usual
impedance
of
phones
having
a
DC
resistance
of
between
2000
and
3000
ohms.
Maximum
audio
output
available
at
the
phone
jack
is 15
milliwatts.
(2)
A
five
prong
speaker
socket (
X-1)
is
provided
at
the
rear
of
the
receiver
chassis.
To this
socket
are
brought
the
audio
output
leads.
The
proper
load impe-
dance (
total)
for
the
output
circuit
is
10,000
ohms.
Maximum
undistorted
audio
power
output
available
is
8
watts.
1-
11.
Power
Supply
The
standard
NC-
2-40D
Receiver
is
de-
signed
for
operation
from
a
110/120
volt,
or
220/240
volt
50/60
cycle
power
source.
A
toggle
switch
is
provided
in
the
dual
primary
circuit of
the
power
transformer
to
permit
operation
from
either
voltage. Nor-
mal
power
consumption
is
approximately
100
volt-
amps.
The
built-in
power
supply
de-
livers
all
voltages
required
by
the
heater
and
B
supply
circuits -
4.5
amperes
at
6.3
volts
and
100
milliamperes
at
250
volts,
respectively.
One
side
of
the
AC
input
line
is
connected
through
a 2
ampere
and
a 1
ampere
fuse
housed
in
extractor
posts
marked '
FUSE"
which
are
mounted
at
the
rear
of
the
receiver
chassis.
The
2
ampere
fuse
is
used
in
the
circuit
for
3
115
volt
operation.
Both
2
and
1
ampere
fuses
are
used
for 230
volt
operation.
All
NC-
2-40D
Receivers
are
equipped
with
a
seven
prong
plug
and
socket
combina-
tion
to
permit
portable
or
emergency
opera-
tion
from
batteries.
See
Section
2-3.
1-
12.
Loud
Speaker
The
loud-
speaker
supplied
with
the
table
model
NC-
2-40D
Receiver
is
of the
permanent
magnet
field
type
having
a
nomi-
nal
diameter
of
10
inches.
A
coupling
transformer,
mounted
on
the
loud-
speaker
chassis,
matches
the
voice
coil
to
the
out-
put
impedance
of
the
receiver.
A
shielded
three
wire
cable
and
plug
is
furnished
for
connection
between
the
loud-
speaker
and
re-
ceiver.
A
cabinet,
finished
to
match
the
re-
ceiver,
houses
the
loud-
speaker
for
table
mounting.
The
cabinet
interior
is
lined
with
sound
absorbent
material
to
avoid
any
undesirable
mechanical
resonance.
A
10
1/2
x
19
inch
panel
of
1/8
inch
steel
is
used
to
support
the
ten
inch
loud
speaker
chassis
in
a
relay rack
installa-
tion.
1-13
Pirk-up
Jae!:
A
pick-up
jack
mounted
on
the
front
panel
of
the
receiver
may
be
used
to
con-
nect
auxiliary
apparatus,
such
as
a
phono-
graph
pick-up,
to
the
audio
system
of
the
NC-
2-40D
Radio
Receiver.
This
input
cir-
cuit
is
high
impedance
and
feeds into
the
6SN7GT/G
Audio
Amplifier-
Phase
Inverter
tube.
The
TONE
and
A.F.
GAIN
controls
are
operative
with
this
connection.
SECTION
2.
INSTALLATION
2-1.
Antenna
Recommendations
%ben
using
a
single-
wire
antenna,
the
lead-in
should
be
connected
to
one antenna
input
terminal
and
the
short
flexible
lead,
which
is
attached
to
the
chassis,
should
be
fastened
to
the
other
terminal.
The dimen-
sions
of
the
single-
wire
antenna
system
are
not
critical,
the
recommended
length,
in-
cluding
lead-in,
being
from
75
to
100
feet,
although
any
length
between
25
and
200
feet
may
be
used.
Feed-
lines
of
doublet
systems
should
be
connected
to the
two
input terminals.
The
flexible
lead
is
not
used.
lhe
inner
conductor
of
a
concentric
transmission
line
should
be
connected
to
one
input
terminal.
The
outer
conductor
and
the
flexible
grounding
lead
should
be
connected
to
the
other
terminal.
An
external
ground
connection
to
the
chassis
may
or
may
not
be
necessary.
It
should
be
used
unless
it
reduces
signal
strength.
THE
NC-
2-40D
RECEIVER
ANT
GNa
his.
No.
1.
2-2.
td
Operation
Rear
hew
of
Receiver
After
unpacking
the
NC-
2-40D
Receiver
and
loud-
speaker
from
the
shipping
cases,
proceed
as
follows:
(1)
Remove
the two
coil
carriage
lock-
ing
screws
on
the
right
hand
side
of
the
cabinet
before
attempting
to
slide
the
coil
carriage.
(2)
Make
sure
tubes
are
firmly
in
their
sockets.
(3)
Insert
the
dummy
connector
plug
P-2
in
the
seven
prong
socket
X-2.
(4)
Insert
loud-
speaker
plug
P-1
in
the
five
prong
audio
output
socket
X-1
of
the
receiver.
(5)
Connect
antenna
feed
line.
(6)
Set
primary
selector
switch
for
line
voltage
to
be
used,
i.e.
115
or
230.
(7)
Plug
AC
line cord
in
proper
source
of
supply.
(8)
Set controls
as
recommended
in
Section
3
for
reception
of
signals.
2-3.
flattery
Operation
The
NC-
2-40D
may
be
operated
in
port-
able
or
emergency
service
by
connecting
batteries
to
the
terminals
of
battery
con-
nector
plug
P-3
and
inserting
it
in
socket
X-2
in
place
of
plug
P-2.
See
Fig.
No.
1.
For
normal
operation
with
somewhat
reduced
F-
I )
X-
I
BSW
P-2
F-2 \
X-2
loud-
speaker
output,
a 6
volt
heater
supply
(storage
battery)
should
be
connected
to
terminals
1
and
2
of
plug
P-3,
and
a
180
volt
B
supply
should
be
connected
to
plug.
terminals
5
and
6.
During
battery
opera-
tion
the
Bi-
and
BS» switches
are
operative.
Battery
economy
may
be
effected during
headphones
operation
by
removal
of the
speaker
plug
P-1
from
socket X-1
which
will
open
the
6V6
B
supply
without harming
the
output
tubes.
A
further
economy
of
battery
power
during
headphones
operation
may
be
accomplished
by
removal
of
the two
6V6
out-
put
tubes
from
their
sockets.
The
AC
line
switch
does
not
render
the
Receiver
in-
operative
during
battery
operation.
It
is
necessary,
therefore,
to
remove
the
battery
plug
to
effectively
disconnect
the
battery
from
the
Receiver.
Do
not
attempt
to
use
plug
P-2
for
battery
connection,
since
the
jumper
be-
tween
terminals
1
and
7
would
be incorrect.
.
The recommendations
of
Section
3,
OP-
ERATION,
apply
to
the
battery
powered
NC-
2-40D.
2-
1.
Laud
Speaker
If
the
installation
is
such
that
the
loud-
speaker
will
be
placed
close
to
the
receiver,
the
most
desirable
position
is at
the
side.
Placing
the
loud-
speaker
on
top
THE
NC-
2-40D
RECEIVER
5
of
the
receiver
is
not
desirable
since
vi-
bration
from
the
speaker
might
possibly
in-
3-
1.
Controls
troduce
microphonic
noises
which
would
not
otherwise
be
noticlable.
SFA
I
ION
3.
ILTION
The
MAIN
TUNING
control
knob
is
located
at
the
middle of
the
front
panel
and
operates
a
three-
gang variable
capaci-
tor
Gl
through
a
44
to
1
ratio
reduction
drive
mechanism.
The
main
dial has
ten
ac-
curately
calibrated
scales,
the
scale
in
use
being
definitely
indicated
by
band
mar-
kers
appearing
at
the
scale
ends.
A
dial
pointer
shows
the
frequency
to
which
the
receiver
is
tuned.
The
accuracy
of
the
general
coverage
calibration
can
be
relied
upon
to
be
better
than
plus
or
minus
1%.
Immediately
below
the
pointer
is
a
vernier
dial
which
may
be
used
to
accurately
log
incoming
signals.
The
tuning
system
of
the
NC-
2-40D
is
truly
single
control;
in
fact,
the
MAIN
TUNING
control
referred
to
above
is
used
for
band
changing
as
well
as
tuning.
To
select
either
a
general
coverage
or
bandspread
coil
range,
the
MAIN
TUNING
control
knob
is
pulled
out
about
1/4
inch.
When
this
is
done,
the
dial
and
capacitor
drive
mechanism
is
disengaged
and
the
knob
is
geared
to
the
coil
casting.
As
the
knob
is
turned,
the
coil
carriage
is
moved
across
the
chassis
until
the
proper
coil
pin
contacts
engage
the
circuit
contactors,
as
indicated
by
the
scale
markers.
Approx-
imately
one
full
turn
of
the
MAIN
TUN-
ING
knob
is
required
to
change
from
one
general
coverage
range
to an
adjacent
general
coverage
range.
Approximately
one
quarter
turn
of
the
knob
is
required
to
shift
from
a
general
coverage
range
to
the
associated
bandspread
range
near
the
high
frequency
end.
The
knob does not
turn
smoothly
between
ranges,
but
only
a
few
minutes
is
required
to
become
familiar
with
its
action.
After
the
desired
range
has
been
selected,
the
tuning
knob
is
pushed
in
to
its
original
position,
engaging
the
ca-
pacitor
drive
and
disengaging
the
coil car-
riage
rack.
The
LIMITER
control,
at
the
left-
hand
side
of
the
receiver
panel,
is
used
to
POWER
SWITCH
METER
LIMITER
CONTROL
CONTROL
SWITCH
PHONES
JACK
R F
GAIN
CONTROL
MAIN
TUNING
DIAL
'
n111.11111110118111
.1
"nnil
BAND
CHANGE
AND
TUNING
KNOB
VERNIER
DIAL
TONE
CONTROL
SELECTIVITY
CONTROL
C W
OSC
CONTROL
PICK-UP
JACK
A F
GAIN
CONTROL
Fig.
No.
2.
Front
View
of
Receiver
6
THE
NC-
2-40D
RECEIVER
adjust
the
DC
potential
applied
to
the
ele-
ments
of
the
series
valve
noise
limiter
tube.
The limiter
circuit
is
thus
provided
with
an
adjustable
threshold
at
which
lim-
iting
starts.
Any
audio
voltages,
or
peaks,
in
excess
of
this
threshold
are
pre-
vented
from
reaching
the
audio
amplifier.
With
the
LIMITER
control
set
at
0,
the
limiter
circuits
will pass
all
but
the
strongest
audio
peak
voltages;
when
the
control
is
set
at
10,
the
threshold
is
low-
ered
to
a'point
where
the
audio
signal
will
be
distorted
due
to
suppression
of
the
pos-
itive
peaks.
The
R.F.
GAIN knob
is
located
be-
low
and
to
the
right
of
the
LIMITER
knob.
It
is
used
to
adjust
the
amplifica-
tion of
the
R.F.
amplifier
and
two
I.F.
am-
plifier
tubes.
Amplification
increases
as
the
control
is
turned
clockwise
towards
10.
A
CONIBOL
SWITCH
is
mounted
above
the
R.F.
GAIN
control
knob.
In
the
AVC
position,
the
automatic
volume
con-
trol
circuits
are
in
operation
and
the
S-
meter
is
switched
on;
in
the
MVC
posi-
tion,
automatic
volume
control
and
the
S-
meter
are
turned
off;
in
the
CWO
po-
sition,
the
beat
frequency
oscillator
is
turned
on and
automatic
volume
control
and
S-
meter
are
turned
off.
The
POWER
SUPPLY
control
knob
is
directly
above
the
CONTPOL
SWITCH.
In
the
counterclockwise
position,-
OFF,
the
receiver
is
turned
off,
the
primary
circuit
being
opened
by
the
AC
line
switch;
in
the
mid-
position,
8+
OFF,
the
AC
line
switch
is
turned
on
but
the
B
supply
circuits
are
incomplete
since
the
B+
switch
is
open;
in
the
clockwise
position,
B+
ON,
the
B+
switch
is
closed,
completing
the
B
supply circuit. The
8+
OFF
position
may
thus
serve
as
a
stand-by
switch
for
rendering
the
receiver
inoperative,
as
may
be
required
during
transmission
periods.
The
PRIMARY
SELECTOR
SWITCH
of
the
power
transformer
is
mounted
on
the
re-
ceiver
chassis
to
the
right
of
the
power
transformer.
This
switch
selects
the
prop-
er
circuit
arrangement
of
the
dual
primary
for
operation
from
either
115
or
230
Volt
power
source.
There
is
a
shield
provided
to
prevent
unintentional
throwing
of
the
switch.
The
A.F.
GAIN
control
knob
is
lo-
cated
to
the
right
of
the
MAIN
TUNING
control.
It is
used
to
adjust
the
audio
amplification
of
the
receiver.
Audio
am-
plification
increases
as
the
control
is
turned
towards
10
on
the
scale.
The
PHASING
and
SELECTIVITY
knobs,
located
above
the
A.F.
GAIN
knob,
con-
trol
the
action
of
the
crystal
filter.
When
the
SELECTIVITY
control
is
set
at
OFF,
the
crystal.
is
switched
out of
the
circuit.
With
the
crystal
switched
out,
the
phasing
control
has
little
influence
on
receiver
performance.
With
the
SELEC-
TIVITY
control
knob
set
at
any
point
between
1
and
5,
inclusive,
the
crystal
filter
is
in
operation,
selectivity
in-
creasing
as
the
knob
is
advanced
to
5.
See
Fig.
No.
2.
The
PHASING
control
is
then
used
to
balance
the
crystal
bridge
circuit
and
eliminate
interfering
signals
or
heterodynes.
See
Sections
3-2
and
3-3.
The
C.W.
OSC.
control
knob
located
to
the
right
of
the
PHASING
control
is
used
for
varying
the
frequency
of
the
beat
oscillator.
At
0
on
the
C.W.
C.
scale,
the
beat
oscillator
is
tuned
to the
inter-
mediate
frequency.
See
Section
3-3.
A
TONE
control
knob
is
located
above
the
C.W.
OSC.
knob
and
is
used
to
vary
the frequency
characteristic
of
the
audio
amplifier
as
previously
described.
A
BSW
terminal
panel
is
mounted
at
the
rear of
the
receiver
chassis.
The
termi-
nals
are
connected
in
parallel
with
the
14
switch.
If
external (
remote)
stand-by
con-
trol
is
desired,
it
can
be
accomplished
by
connecting
a
switch
or
relay
to
these
ter-
minals.
3-2.
Phone
Reception
After
the
equipment
is
properly
in-
stalled,
in
accordance
with
Section
2,
it
is
placed
in
operation
by
turning
the
POWEP
SUPPLY
switch
to
B+
ON.
The
LIM-
ITER
control
should
be
set
at
0.
The
CONTROL
SWITCH
should
be
set
at
AVC.
The
PHASING
knob
should
be
set
at
0;
the
SELECTIVITY
at
OFF;
the
TONE
con-
trol
should
be
set
to
give
the
desired
audio
characteristic;
the
R.F.
GAIN
control
should
be
advanced
to
some
point
between
8
and
10,
depending
upon
receiving
conditions;
the
A.F.
GAIN
control
should
be set
at the
point
providing
the
desired
audio
volume.
The
receiver
is
now
adjusted
for
the
reception
of
phone
signals
and
will
THE
NC-
2-40D
RECEIVER
7
tune
to
the
frequency
indicated
by
the
MAIN
TUNING
dial.
The
C.W.
OSC.
knob
has
no
influence
on
receiver
performance
under
these
conditions.
With
the
CONTROL
SWITCH
set
in
the
AVC
position,
as
recommended,
the
R.F.
GAIN
knob
should
be
advanced
as
far
as
receiving
conditions
permit,
or
until back-
ground
noise
becomes
objectionably
loud.
Audio
output
should
be
adjusted
entirely
by
means
of
the
A.F.
GAIN
knob.
The
operator
must
remember
that
automatic
vol-
ume
control
action
will
be
restricted
un-
less
the
B.F.
GAIN
knob
is
fully
ad-
vanced.
The
CONTROL
SWITCH
may
be
set
at
MVC,
in
which
case
the
operator
must
be
careful
not
to
advance
the
R.F.
GAIN
knob
to
a
point
where
I.F.
or
audio
ampli-
fier
overload
occurs.
Such
overload
is
in-
dicated
by
distortion.
In
general,
the
A.F.
GAIN
control
may
be
set
about
half-
way
on,
i.e.,
at
5
and
the
audio
output
ad-
justed
by
means
of
the
B.F.
GAIN
con-
trol.
If
a
signal
is
weak
and
partially
ob-
scured
by
background
noise
and
static,
best
signal-to-noise
ratio
will be
obtained
by
turning
the
TONE
control
towards
the
LOW
position.
The most
effective
set-
ting
must
be
determined
by
trial
as
too
much
attenuation
of
high
audio
frequencies
will
impair
the
intelligibility
of
speech.
When
a
signal
is
accompanied
by
static
peaks or
noise
pulses
of high
intensity
and
short
duration,
the
best
signal-to-noise
ratio
will
be
obtained
by
advancing
the
LIMITER
control
towards
10.
The
best
setting
must
be
determined
by trial
as
too
much
limiter
action
will
impair
audio
qual-
ity.
If
static
peaks
and
noise
pulsés
are
extremely
strong
or
if
they
are
of
fairly
long
duration,
the
effectiveness
of
the
limiter
will
be
best
with
the
CONTROL
SWITCH
in
the
MVC
position.
In
such
cases
both
R.F.
GAIN
and
LIMITER
con-
trols
must
be
carefully
adjusted
for
opti-
mum
signal-to-noise
ratio.
The
selectivity
of
the
receiver
may
be
adjusted
by
means
of
the
crystal
filter.
The
normal
setting
of
the
SELECTIVITY
control
in
phone
reception
is at
one
of
the
positions
affording
broad
selectivity.
Po-
sitions
1
or
2
are
recommended.
Selectivi-
ty
may
be
progressively
increased
by
turn-
ing
the
SELECTIVITY
control
to
posi-
tions
3,
4
or
5
although
advancing
the
con-
trol
too
far
will
increase
selectivity
to
a
degree
where
phone
signals
become
unintel-
ligible.
The
PHASING
control
is
used
to
eliminate
or
attenuate
heterodynes
func-
tioning
only
when
the
SELECTIVITY
con-
trol
is
at
some
position
other
than
OFF.
The
normal
setting
of
the
PHASING
con-
trol
in
phone
reception
is
at
0
on
the
scale.
If,
after
a
signal has
been
tuned
in,
an
interfering
signal
causes
a
hetero-
dyne
or
whistle,
the
PHASING
control
should
be
adjusted
until
the
interference
is
reduced
to
a
minimum.
The
setting
of
the
PHASING
control
which
próvides
max-
imum
attenuation
of
the
heterodyne
will
de-
pend
upon
the
pitch
of
the
heterodyne
whistle.
If
the
beat note
is
above
1000
.
cycles,
the
optimum
PHASING
control
setting
will
be
near
0;
if
the
beat
note
is
300
or
400
cycles,
the
optimum
PHAS-
ING
control
setting
will
be
near
one
end of
the
scale
or the other,
depending
upon
whether
the
interfering
signal
has
a
higher
or
lower
frequency
than
the
desired
signal.
It
is
recommended
that
the
TONE
control
be
set
in
the
HIGH
position
when
using
the
crystal
filter
in
phone
re-
ception.
The
resulting
attenuation
of
low
audio
frequencies
tends
to
compensate
for
the
side-
band
cutting
action
of
the
crystal
filter.
3-3.
C.
W.
Receptions
The
initial
adjustment
of
the
receiver
for
C.W.
reception
is
as
described
in
Sec-
tion
3-2,
except
that
the
CONTROL
SWITCH
must
be
in
the
CWO
position.
The
C.W.
OSC.
control
should
be set
at
mid-
scale.
The
sensitivity
of
the
receiver
should
be
adjusted
by
means
of
the B.F.
GAIN
control,
care
being
taken
not
to
advance
the
control
to
the
point
where
strong
sig-
nals
will
cause
I.F.
or
audio
amplifier
overload,
as
indicated
by
excessive
thump-
ing.
The
action
of
the
TONE
and
LIMI-
TER
controls
will
be
similar
to
that
described
under
Section
3-2.
When
receiv-
ing
C.W.
signals,
it
will
be
possible
to
advance
both
TONE
and
LIMITER
controls
considerably
further
than
is
possible
in
8
THE
N(:2-
40D
RECEIVER
phone
reception,
since audio
distortion
is
relatively
unimportant.
Turning
the
C.
W.
OSC.
control,
which
is
a
variable
air
capacitor,
will
change
the
characteristic
pitch
of
the
re-
ceiver
background
noise.
This
control
en-
ables
the
operator
to
vary
at
will
the
au-
dio
beat
note of
any
C.W.
signal
to
a
pre-
ferred
tone.
The
pitch
will
become
higher
as
the
beat
frequency
oscillator
is
detuned
from
the
I.F.
amplifier.
With
the
C.W.
OSC.
control
set
at
2
or
3 (
on
either
side
of
0),
the
characteristic
pitch
of
the
receiver
background
noise
will
be
in
the
neighborhood
of
2000
cycles.
Under
these
conditions,
the
audio
beat
note of
any
C.W.
signal
will show
a
broad
peak
at
approxi-
mately
2000
cycles.
This
peak
will
appear
on "
one
side
of
the
carrier"
only
and
the
*
other
side,
where
the
audio
beat
note
is
around
2000
cycles,
will
be
considerably
weaker.
This
characteristic,
known
as
"semi-
single
signal",
is
helpful
in
receiv-
ing
weak
signals
through
interference.
As
stated
in
Section
3-2,
the
selec-
tivity
of
the
receiver
may
be
adjusted
by
means
of
the
crystal
filter,
the
action
of
the
SELECTIVITY
and
PHASING
controls
in
C.W.
reception
being
similar
to
that
de-
scribed.
It is
possible,
however,
to
uti-
lize
the
full
range
of
crystal
filter
se-
lectivity
in
C.W.
reception.
Maximum
se-
lectivity
is
obtained
with
the
SELEC-
TIVITY
control
set
at
5.
With
this
setting
the
single-
signal
effect,
outlined
I-
1.
Tube»
Failure.»
above,
becomes
very
pronounced;
in
other
words,
the
audio
beat
note
is
very
sharply
peaked
at
a
definite
audio
frequency
which
is
determined
by
the
setting
of
the
c.e.
OSC.
control.
The
operator
may
have
diffi-
culty
in
finding
the
audio
peak
when
first
attempting
to
use
the
crystal
filter.
Aft-
er
a
signal has
been
accurately
tuned
to
give
peak
response,
the
B.F.
GAIN
con-
trol
may
need
to
be
retarded
in
order
to
prevent
I.F.
or
audio
overloading.
With
the
receiver
tuned
to '
trystal
peak",
an
interfering
signal
may
be
attenuated
by
proper
setting
of
the
PHASING
knob
since
this
control
does
not
appreciably
affect
the
desired
signal.
3-
1.
Measurement
ol
Signal
Strength
To
make
a
measurement
of
signal
strength
by
means
of
the
S-
meter,
the
B.F.
GAIN
control
must
be
advanced
to
10,
and
the
CONTROL
SWITCH
set
at
the
AVC
position.
The
crystal
filter
should
be
turned
OFF
by
means
of
the
SELECTIVITY
control;
the
PHASING
knob
set
at
0.
The
TONE,
LIMITEB
and
A.F.
GAIN
controls
do
not
affect
the
meter
reading.
Tuning
the
receiver
to
a
signal
will
cause
the
meter
to
read,
indicating
the
signal
input
in
S-
units
or
in
decibels
above
the
S-9
level.
Measurement
of
the
signal
strength
of
C.W.
signals
cannot
be
made
with
the
beat
frequency
oscillator
in
operation.
SE1
TION
1.
SE11‘11
E
AND
TENT
DATA
Failure
of
a
vacuum
tube
in
the
re-
ceiver
may
reduce
the
sensitivity,
produce
intermittent
operation,
or
cause
the
equip-
ment
to be
completely
inoperative.
In
such
cases,
all
tubes
should
be
checked
either
in
an
analyzer
or
similar
tube
testing
equipment,
or
by
replacement
with
tubes
of
proven
quality.
All
tubes
should
be
marked
as
they
are
removed
from
the
receiver
so
that
they
may
be
returned
to
their
original
sockets
thereby
reducing
the
necessity
for
realignment.
Individual
tubes
of
the
same
type
will
vary slightly
in
their
characteristics
and
it
is
well
to
remember
this
fact
when
re-
placements
become
necessary.
Even though
the
circuit
is
designed
to
reduce
the
ef-
fect
of
such
variations
to
a
minimum,
the
high
frequency
oscillator
and
I.F.
tubes
should
be
selected with
some
care.
A
re-
placement
high
frequency
oscillator
should
be
checked
in
the
receiver
to
make
sure
that
the
inter-
electrode
capacities
are
the
same
as
those
of
the
tube
originally
em-
ployed.
This
is
easily
determined
by
not-
ing
any
change
in
dial
calibration,
partic-
ularly
in
the
amateur
bandspread
ranges.
Substitution
of
new
tubes
in
the
I.F.
amplifier
may
possibly
alter
overall
gain
and
selectivity
characteristics.
Instruc-
tions
for
realignment
are
given
in
detail
in
Section
5-2.
THE
NC-
2-40D
RECEIVER
9
One
other
point
should
be
checked
when
trying
the
new
high
frequency
oscillator;
a
fairly
strong
steady
signal
should
be
tuned
in,
preferably
on
some
frequency
above
10
mc.;
the
beat
frequency
oscillator
should
be
turned
off;
jarring
the
receiver,
or
lightly
tapping
the
tube,
should
not show
any
evidence
of
noise
in
the
output.
4-2.
Circuit
Failures
Even
though
all
component
parts
of
the
receiver
have
an
ample
factor
of
safety,
failure
may occur
in
individual
cases.
Ex-
cluding
tubes,
the
most
common
failure
will
probably
be
due
to
some defect
in
a
capaci-
tor
or
resistor.
Measurement
of voltage
in
accordance
with
Section
4-4
will
no
doubt
show
where
failure
has
occurred.
A
by-pass
capacitor
which
has failed
may
cause over-
load of
associated
resistors.
These
resis-
tors
should
be
checked
for
any
change
in
resistance.
An
open
capacitor,
often
the
cause
of
loss
of
sensitivity
or
oscilla-
tion,
may
be
checked
by
temporarily
con-
necting
a
good
capacitor
across
it.
Inter-
mittently
poor
connections
can
usually
be
located
by
lightly
tapping
each part
with
a
piece
of
insulating
material.
4-3.
Stage
Gala
Measurement»
The
sensitivity
measurements
listed
below
are
made
with
equipment
set
up
as
specified
in
Section
5-1.
The
CONTFt0L
SWITCH
should
be
set
at
MVC,
the
A.F.
GAIN
at
10,
the
SELECTIVITY
at
OFF
and
the
PHASING
at
0.
The signal
gener-
ator
should
be
adjusted
to
deliver
a
test
signal of
455
plus
or
minus
2
kc.
either
modulated
or
unmodulated. The high
output
lead
should
be
attached
to
the
grid
of
the
tube
specified
in
the
table
below
and
the
ground
lead
connected
to
the
receiver
chas-
sis.
With
1
milliwatt
output
at
the
phone
jack,
the
test
signal
should
be
within
the
limits
specified
below.
Terminal
Test
Signal
First
Det.
First
I.F.
Sec.
I.F.
Sec.
Det.
Grid...
Grid...
Grid....
Grid....
50
i
10
Microvolts
250
450
Microvolts
50000 +
10000
Microvolts
Over
1
volt
4-1.
Voltage
Tabulation
All
measurements
of
voltages
should
be
made
with
the
equipment
connected
for
nor-
mal
operation
with
AC
supply
of
115
volt,
50/60
cycle
or
230
volt,
50/60
cycle.
Ex-
cept
as
noted,
the
B.F.
GAIN
knob
is
set
at
10,
the
LIMITER
knob
set
at
0
and
the
CONTROL
SWITCH
knob
set
at
MVC.
A
DC
Voltmeter
of
1000
ohms
per
volt
sensi-
tivity
should
be
used.
The
following
table
must
not
be
considered
as
a
list
of
the
ac-
tual
operating
voltages
since
loading
ef-
fects
of
the
measuring
instrument
will
dis-
turb
many
of
the
circuits
and
alter
normal
voltage
distribution.
All
voltages
are
measured
between
specified
terminal
and
chassis.
Tube
Terminal
DC
Volts
+
15%
P.F.
Amp.
Grid
R.F.
Amp.
Cathode
B.
F.
Amp.
Cathode
P.F.
Amp.
Screen
R.F.
Amp.
Plate
First
Det.
Grid
First
Det.
Cathode
First
Det.
Screen
First
Eét.
Plate
ELF. Osc.
Grid
H.F.
Osc.
Cathode
H.F. Osc.
Plate
First
I.F.
Grid
First
I.F.
Cathode
First
I.F.
Cathode
First
I.F.
Screen
First
I.F.
Plate
Sec.
I.F.
Grid
Sec.
I.F.
Cathode
Sec.
I.F.
Cathode
Sec.
I.F.
Screen
Sec.
I.F.
Plate
Sec.
Det.
Grid
Sec.
Det.
Cathode
Sec.
Det.
Plate
Limiter
Grid
Limiter
Cathode
Limiter
Cathode
Limiter
Plate
A.V.C.
Grid
A.V.C.
Cathode
A.V.C.
Screen
A.V.C.
Plate
B.F.
Ose.
Grid
B.F.
Osc.
Cathode
B.F. Osc.
Screen
B.F.
Osc.
Plate
Amp.-
Inv.
Grids
Amp.-
Inv.
Cathode
Amp. -
Inv.
Plates
O
3 A
19
A*
65
B
190
P
o
1 A
55
B
185
B
O
85
B
O
4
19
65
185
o
5
19
70
185
o
6
•
185
-6
4.5
O
O
-26
A
A*
A
A*
A
A
A
AE
-45
AE
E
E
o
o
o
10
22
O
4
90
AF
AF
A
10
THE
N
C-
2-10D
R
EC
EI
V
ER
Tube
Terminal
DC
Volts
15%
Audio
Grids
Audio
Cathodes
Audio
Screens
Audio
Plates
B+
Common
R-
Common
-25
A
-45
A
190
B
180
B
195
B
-60
Li
General
Legend
A --
0
to
50
voltmeter
scale.
B 0
to 250
voltmeter
scale.
C --
Accurate
measurement
cannot
be
made.
D --
LIMITER
knob
set
at
10.
E --
CONTROL
SWITCH
knob
set
at
AVC.
F
CONTROL
SWITCH
knob
set
at
CWO.
*
R.F.
GAIN
knob
set
at
0.
SECTION
5.
ALIGNMENT
DATA
All
circuits
are
carefully
aligned,
before
shipment,
using
precision
crystal
oscillators
which
insure
close
conformabil-
ity
to
the
dial
calibration.
No
readjust-
ment
will
be
required,
therefore,
unless
the
receiver
is
tampered
with
or damaged.
To
determine
the
necessity
for
re-
alignment,
the
receiver
should
first
be
carefully
checked
against
its
normal
per-
formance
as
described
in
Section
3.
In
no
case
should
realignment
be
attempted
unless
tests
indicate
that such
realignment
is
necessary.
Even
then,
it
must
be
remem-
bered
that
the NC-
2-40D
is
a
communica-
tions
receiver
and
should
not
be
serviced
or
realigned
by
any
individual
who
does
not
have
a
complete
understanding
of
the
func-
tioning
of
the
equipment
and
who
has not
had
previous
experience
adjusting
a
similar
type
of
receiver.
lhe
coil
group
which
is
plugged
into
the
circuit,at
any
time
is
the
one
directly
underneath
the
three
gang
master
tuning
ca-
pacitor.
The
coil
nearest
the
front
panel
of
the
receiver
is
in
the
H.F.
oscillator
circuit,
the
middle
coil
is
in
the
first
detector
circuit
and the
coil
nearest
the
antenna
input
terminal
panel
is in
the
B.F.
amplifier
circuit.
See
Fig.
No.
5.
All
coils
have
individual
general
coverage
trimmer
capacitors.
The
H.F.
os-
cillator
circuits
of
broadcast
ranges
E &
F
have,
also,
general
coverage variable
se-
ries
padding
capacitors.
All
coils
of
ranges
A,
B,
C
and
D
have
bandspread
trim-
mer
capacitors.
Variable
series
padding
capacitors
are
used
in
all H.F.
oscillator
bandspread
circuits.
These
capacitors
are
identified
on Fig.
No.
5.
Adjustment
of
general
coverage
cir-
cuits affects
the
alignment
of
the
band-
spread
circuits.
On
the
other
hand,
band-
spread
circuit
adjustments
have
little
ef-
fect
on
general
coverage
circuit
alignment.
This
fact
must
be
kept
in
mind
when
any
high
frequency
circuit
is
adjusted.
A
screw
driver
having
a
metal shaft
may
be
used
to
make
adjustments
in
the
high
fre-
quency
circuits
but
capacity
effects
will
be
noticeable,
and
the
shaft
should
not
touch
any
part
of
the
aluminum
casting.
Before
proceeding
with
the
alignment
of
any
circuit
of
the
receiver,
the
equip-
ment
must
be
set
up
as
specified
in
Section
2,
except
that
the
antenna lead-in
or
transmission
line
must
be
disconnected.
An
output
meter
having
a
20,000
ohm
resistive
load
should
be
connected
to
the
phone
out-
put
jack.
The
POWER
SUPPLY
knob
should
be
set
at
B+
ON
and
the
R.F.
GAIN
knob
set
at
10.
The
TONE
control
knob
should
be
set
at
N
and
the
LIMITER
knob
should
be
retarded
to
0.
Alignment
of
the
equipment may
be
di-
vided
into
three
major
steps:
(1)
I.F.
Amplifier Alignment
(2)
General
Coverage
Alignment
(a)
H.F.
Oscillator
(b)
First
Detector
and
R.F.
Ampli-
fier
(c)
Tracking
of
H.F.
Circuits
(3)
Bandspread Alignment
(a)
H.F.
Oseillator
(b)
First
Detector
and
R.F.
Ampli-
fier
(c)
Tracking of
H.F.
Circuits
The
circuits
MILST
be
tuned
in
the
above
or-
der
when
complete
alignment
is
necessary.
5-
2.
I.F.
Amplifier
Alignment
The
intermediate
frequency
of
the
NC-
2-40D
Receiver•is
455
kilocycles,
plus
or
minus
2
kilocycles.
The
exact
frequency
is
determined
by
the
quartz
crystal
reson-
ator
Y-1.
Tuning
capacitors
are
provided
on
the
THE
NC-
2-40D
RECEIVER
11
6V6
AUDIO ----
6V6
AUDIO -
5Y3G
RECT.
--
S-5
T-1 --
C-35
C-38
L-1
L-2 -
S-IB
f
i
M
R-46
r<-28
S-
2A
I-2
6J5-
H F
OSC
bSN7GT/G
AMP-INV.
I-3
C-40
Y-
I
C-411
S-4
C-48
6SK7
2ND
IF
C-4513
-
7-3
C-
45A
C-436
T-2
6V6
AM
C.
C-
43A
6SK7
RE'
AMP
6SL7GT/G
DEI
-
UN.
6K7
1ST
IF
6K8
1ST.
DET
6SJ7
C.W.
OSC
C-42
C-47
NN
T-4
\ \
R-34
I
C-49
C-
a9
Fig.
No.
3.
Top
crystal
filter
and
on
each
transform-
er.
These capacitors
are
designated
by
symbol
numbers
C-39,
C-41,
C-42,
C- 43A,
C-
43B,
C-
45A
and
C-
45B
on
Figs.
Nos.
3
and
4.
The
high
output
lead
of
an
accurately
calibrated
signal
generator
should
be
con-
nected
to
the
grid
terminal
of
the
first
detector
tube
and
the
grounded
lead
to
any
convenient
point
on
the
chassis.
The
flex-
ible
lead
need not
be
disconnected
from
the
grid
of
the
tube.
Connection
is
made
di-
rectly
from
the
output
jack
of
the
signal
generator,
the
dummy
antenna
being
omitted.
lhe
CONTHOL
SNITCH
of
the
receiver
should
be
in
the
C110
position
and the
modulation
of
the
signal
generator
turned
off
to
pro-
vide
a
steady
C.11.
test
signal.
The
PHASING
control
of
the
receiver
should
be
set
at
0
and the
SELECTIVITY
con-
trol
at
5.
The
A.F.
GAIN
control
should
be
fully
advanced.
View
of
Receiver
Adjust
the
output
attenuator
of
the
signal
generator
to
provide
a-
signal
of
ap-
proximately
100
microvolts
and
vary
the
tuning
control
of
the
signal
generator
slowly
between
the
frequencies
of
453
and
457
kilocycles.
At
some
frequency
between
these
limits
the
I.F.
amplifier
of
the
re-
ceiver
will
show
a
very sharply
peaked
re-
sponse,
as
indicated
on
the
output
meter.
The
output
attenuator
of
the
signal
gener-
ator
has
been
tuned
to the
I.F.
peak
in
or-
der
to
avoid
I.F.
or
audio
overload;
the
C.W.
OSC.
control
must
be set
to
provide
an
audio
beat note
in
the
middle
of
the
audio'
range (
between
400 and
1000
cycles).
The
I.F.
tuning
capacitors,
C-39,
C-
43A,
C-
43B,
C-
45A
and
C-
45B,
should
each
be
carefully
adjusted
to
give
a
maximum
reading
on
the
output
mete¡.
The
order
in
which
the
adjustments
are
made
is
not
im-
portant.
While
making
I.F.
amplifier
ad-
justments,
it
will
be
necessary
to
retard
12
THE
NC-
2-40D
RECEIVER
the
attenuator
of
the
signal
generator
if
the
readjustment
increases
I.F.
amplifier
gain
to
the
point
where
overload
occurs.
The
crystal
filter
SELECTIVITY
knob
should
then
be
set
at
1
and
the
signal
generator
detuned
between
3
and
4
kilo-
cycles
either
side
of
the
crystal
frequen-
cy.
Capacitor
C-42
should
be tuned
for
maximum
output
meter
reading.
After
this
adjustment
is
made,
the
SELECTIVITY
knob
should
be
set
at
OFF
and
the
signal
generator
retuned
to
exact
crystal
frequen-
cy.
Compensator
capacitor
C-41 should
then
be
adjusted
for
maximum
reading
on
the out-
put
meter.
The
performance
of
the
I.F.
amplifier
and
audio
circuits
may
be
checked
against
the
stage
gain
data
in
Section
4-3
after
alignment
has
been
completed.
Selectivity
may
be
checked
against
the
curves
of
Ng.
No.
1.
The
quartz
crystal
resonator
Y-1 may
be
checked
at
the
conclusion
of
I.F.
ampli-
fier
alignment
as
follows:
The SELEC-
TIVITY
control
should
be
set
at
5
and
the
signal
generator
tuned
to
the
crystal
frequency.
The
output
meter reading
should
be
noted.
When
the
SELECTIVITY
knob
is
turned
to
OFF,
the
meter
reading
should
decrease
1
to
2
db.
provided
the
PHAS-
ING
knob
is at
0.
An
increase
in
meter
reading
can,
in
most
cases,
be traced
to an
improper
adjustment
in
the
I.F.
amplifier,
since
the
crystal
resonator
is
mounted
in
a
sealed
holder,
and
it
is
rather
unlikely
that
trouble
will
be
had
from
that
source.
5-3.
General
Camerae,
Aitipagesent
(a)
H.F.
Oscillator
Alignment
is
effected
as
follows:
With
the
coil
range
to
be
aligned
connected
in
the
circuit
and
with
the
receiver
con-
trols
set
as
recommended
in
Section
5-1,
the
MAIN
TUNING
dial
should
be
set
near
the
high
frequency
end
of
the range.
A
signal
generator
should
be
connected
to
the
antenna
input
terminals
through
a
standard
III'
dummy
antenna
and
accurately
tuned
to
deliver
a
signal
of
the
same
frequency
as
that
indicated
by
the
receiver
dial
set-
ting.
If,
when
this
signal
is
tuned
in,
the
dial
reading
is
too
high,
the
capacity
of
the
H.F.
oscillator
general
coverage
circuit
trimmer
C.-52
should
be
decreased
to
make
correction.
Conversely,
low
dial
readings
are
corrected
by
increasing
the
capacity
of
trimmer
C-52.
It
is
imperative
that
the
high
fre-
quency
oscillator
circuits
operate
at
a
higher
frequency
than
that
of
the
first
de-
tector
and
R.F.
amplifier
circuits.
This
can
be
checked
by
tuning
in
the
image
sig-
nal,
which
should
appear
at
a
dial
reading
approximately
910
kilocycles
below
that
of
the
real
signal.
The
image signal
should
be
considerably
weaker
if
the
B.F.
amplifi-
er
is
correctly
aligned
and
a
stronger
test
signal
may
be
required
before
the
image
can
be
found.
If
the
image
does not
appear
at
the
lower
frequency
dial
setting,
the
H.F.
oscillator
circuit
is
incorrectly
adjusted
and
the
capacity
of
the
H.F.
oscillator
trimmer
capacitor
in
question
must
be
de-
creased
until
the real
signal
and
image
signal
appear
at
the
proper
points
on
the
dial.
(b)
First
Detector
and
B.F.
Amplifier.
With
the
signal
generator
adjusted
to
deliver
a
modulated
signal
near
the
high
frequency
limit
of
the
band
to
be
checked,
the
receiver
should
be
tuned
to
give
maxi-
mum
output,
as
indicated
by
the
output
meter.
The
first
detector
and
B.F.
ampli-
fier
trimmer
capacitors
C-51
and
C-50
re-
spectively,
should
then be
varied
until
the
output
meter
reads
maximum.
Co
the
highest
frequency
bands,
adjustment
of
the
first
detector
and
B.F.
amplifier
trimmers
may
change
the
calibration
of
the
high
frequen-
cy
oscillator,
necessitating
retuning
of
the
MAIN
TUNING
dial.
If
these
trim-
mers
should
require
considerable
realign-
ment,
it
may
be
necessary
to
readjust
the
high
frequency
oscillator
trimmer
C-52
in
order
to
maintain
correct
calibration.
A
very simple
and
quick
method
of
first
detector
and
R.F.
trimmer
alignment
may
be
used
if
a
signal
generator
is
not
available.
This
method
consists
of
setting
the
trimmers
at
the
adjustment
which
pro-
vides
maximum
circuit
or
background
noise.
It will be
found
that
trimmer
settings
un-
der
this
method
are
sufficiently
sharp
to
provide
good
alignment,
although
the
ad-
justment
must
be
made
with
care
to
avoid
alignment
to
the
image
frequency.
(c)
Tracking
of
H.F.
Circuits
After
the
H.F.
oscillator,
first
de-
tector
and
B.F.
amplifier
trimmers
have
been
properly
set
at
the
high
frequency
THE
NC-
2-40D
RECEIVER
13
limit of
the range,
the
receiver
should
be
tuned
to
a
frequency
toward
the
low
fre-
quency
end.
Tracking
at
any
point
up to
the
low
frequency
limit
may
be
checked
by
adjusting
the
signal
generator
to
the
prop-
er
frequency
and
testing
the
settings of
the
first
detector
and
R.F.
amplifier
trim-
mers
for
maximum
gain.
Calibration
may
be
checked
also
at
these
points.
After
such
a
test,
all
trimmers
checked
should
be
reset
at
the
high
frequency end
of
the
band
since
their
settings
are
most
critical
at
this
point.
Errors
in
tracking
near
the
low
fre-
quency
limit
of
the
band
can
be
caused
by
defects
in
any
of
three
circuit
elements.
(1)
The
tuning
capacitor
section.
(2)
The
circuit
inductance.
(3)
The
H.F.
oscillator
series
padding
capacitor.
In
order
to
determine
if
one
or more
sections
of
the
master
tuging
capacitor
C-1
are the
cause
of
any
mistracking
present,
it
is
necessary
to
make
the
check
described
above
on
two
or
more different
bands.
If
the
same
tracking
error
appears
on
all
bands,
the
master
tuning
capacitor
is
def-
initely
at
fault.
The
error
should
be cor-
rected
by
permanently
bending
the
rotor
or
stator
plsates
to
provide
the
proper
capac-
ity.
If
the
tracking
error
appears
only
in
the
R.F.
amplifier
or
first
detector
stage
and
on
only
one
band,
the
inductance
of
the
tuned
circuit
of
the
stage
is
incorrect.
Should
the
tracking
checks
indicate
that
the
H.F.
oscillator
circuit
of
a
particular
band
is
at
fault,
either
the
inductance
of
the
circuit,
the
series
padding
capacitor
or
both
may
be
responsible.
After
any
change
or
readjustment
is
made
to
any
high
frequency
circuit
induct-
ance
or
series
padding
capacity,
it
will
be
necessary
to
realign
the
associated
trimmer
at
the
high
frequency
limit
of
the
coil
range.
lracking
should
then be
rechecked.
5-4.
Band-
Spread
Alignment
(a)
H.F.
Oscillator
The
method
of
adjusting
the
H.F.
os-
cillator
bandspread
trimmer
C-53
of
any
band
is
the same
as
that
described
under
Section
5-3 (
a)
above.
As
stated
previous-
ly (
Section
5-1),
the
adjustment
of
the
general
coverage
trimmers
must
not
be
al-
tered
at
this
time.
(b)
First
Detector
and
R.F.
Amplifier
The
method
of
adjusting
the
band-
spread
trimmers
C-59
and
C,62 of
the
first
detector
and
R.F.
Amplifier
circuits
is
the
same
as
that
described
under Section
5-3.
(c)
Tracking
of
H.F.
Circuits
After
steps (
a)
and (
b)
have
been
com-
pleted,
the
MAIN
TUNING
control
should
be
turned
to
the
low
frequency
band
limit,
and
the
accuracy
of
the
dial
reading
check-
ed.
If the
dial
reading
is
too
low,
the
capacity
of
the
series
padding
capacitor
C-54 (
See
Fig.
No.
5)
should
be
increased
until
the
dial
reading
is
correct,
and
vice
versa.
The
MAIN
TUNING
control
should
then
be
reset
at
the
high
frequency
band
limit,
and
step (
a)
repeated.
Recheck
the
low
frequency
dial
reading
and
repeat
the
whole
procedure
if
necessary.
The
detector
and
R.F.
amplifier
stages
have
fixed
bandspread
padding
capacitors.
These
circuits
will,
therefore, track
pro-
perly
with
the
H.F.
oscillator
stage
pro-
vided
that
the
general
coverage
circuits
are
properly
aligned
and
that
the
band-
spread
H.F.
oscillator
circuits
are
accur-
ately
tuned.
5-5.
S-
Meter
Adjustment
The
revised
S-
meter
circuit
in
the
NC-
2-40D
insures
the
stability
of
the
zero
meter
reading
and
requires
no
electrical
adjustment.
A
check
of
the
S-
meter
pointer
zero setting
can
be
made
by turning
off
the
receiver.
If
the
S-
meter
does
not
read
true
zero
the
panel
screw-
adjustment
should
be
used
to
correct
any
inaccuracy.
5-6.
Band
Indicator
Adieuslatent
An
adjustment
for
centering
the
band
indicator
markers
in
the
horizontal
slots
of
the
dial
face
is
located
in
back of
the
MAIN
TUNING
knob.
It is
recommended
that
the
MAIN
TUNING
knob
be
pulled
out
to
engage
the
band
changing
mechanism,
and
turned
clockwise
to
the
last
position
before
the
stop.
The
red
band
marker
should
then
indicate
27.0
to
30.0
mc. (
10
and
11
meter)
bandspread.
To
make
the
ad-
justment,
simply remove
the
tuning
knob
and
set
the
1/4
inch
hexhead screw
as
may
be
required.
The
screw
is
self-locking.
I I
'I'llE
NC-
2-40D
RECEIVER
SEI
TION
6.
PARTS
1.IST
."
,
willml
Function
Type
Rating
CAPACITORS
C-1
C-
lA
C-
1B
C-
1C
C-
2
C-3
C-
4
C-5
C-6
C-7
C-8
C-9
C-10
C-
11
C-12
C-13
C-14
C-15
C-16
C-17
C-18
C-
19
C-20
C-21
C-22
C-23
C-24
C-25
C-26
C-
27
C-28
C-29
C-30
C-31
C-32
C-33
C-34
C-35
C-36
C-37
C-38
C-39
C-40
C-41
C-42
C-43
C-
43A
Main
Tuning
P.
F.
Amp.
Tuning
1st
Det.
Tuning
H.
F.
Osc.
Tuning
B.
F.
Grid
Filter
B.F.
Cathode
Bypass
B.F.
Screen
Bypass
B.
F'.
B+
Bypass
1st
Det.
Cathode
Bypass.. . ...
1st
Det.
Screen Bypass
1st
Det.
B+Bypass ..
1st
I.F.
Grid
Filter
1st
I.F.
Cathode
Bypass ...
1st
I. F.
B +
Bypass .
Sec.
I.F.
Grid
Filter
Sec.
I.
F.
Cathode
Bypass
Sec.
I.F.
Screen Bypass
Sec.
I. F.
B+
Bypass
Sec.
Det.
Plate
Bypass
Sec. Det. to
Limiter
Audio
Coupling....
Sec.
Det.
Cathode
Bypass
Sec.
Det.
I.
F.
Bypass
Limiter
Output
Bypass
Tone
Control
Limiter
to
Inverter
Audio
Coupling
Tone
Control
Inverter-
Audio
Cathode
Bypass
Inverter-
Audio
to
Output Coupling
Inverter-
Audio
to
Output
Coupling
Inverter-
Feedback
Coupl
ing
H.F.
Osc.
Grid.
Beat
Osc.
Grid
Beat
Osc.
Screen
Bypass.
Beat
Osc.
to
Sec.
Det.
Coupling
AVC
Output
Bypass .. . .
AVC
Plate
Bypass
AVC
Cathode
Bypass .
B-
Bypass
AVC
to
Sec.
Det.
Coupling
Power
Supply
Filter
Power
Supply Filter
Crystal
Filter
Input
Tuning
Crystal
Filter
Phasing
Control
Crystal
Filter
Compensating
Crystal
Filter
Output
Tuning
T-
2
Tuning
,
1-2
Primary Tuning
Air
Ki
r
Air
Air
Mica
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Paper
Ceramic
Mica
Ceramic
Paper
Paper
Mica
Elec.
Paper
Paper
Paper
Ceramic
Mica
Paper
Ceramic
Paper
Paper
Paper
Elec.
Ceramic
Paper
Elec.
Air
Air
Mica
Air
Air
Air
225 =
if.
max./sec.
Part
of
C-1
Part
of
C-1
Part
of
C-1
0.005
mfd.,
300
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
600
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
600
vdcw
0.01
mfd.,
600
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
600
vdcw
,
0.01
mfd.,
600
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
400
vdcw
0.
1
mfd.,
600
vdcw
0.01
mfd.,
600
vdcw
1.0
mfd.,
200
vdcw
250
ninf.,
500
vdcw
0.001
mfd.,
500
vdcw
250
mmf.,
son
vdcw
0.01
mfd..,
600
vdcw
0.01
mfd.,
600
vdcw
0.001
mfd.,
500
vdcw
10
mfd.,
50
vdcw
0.1
mfd.,
400
vdcw
0.1
mfd.,
400
vdcw
O.
1
mfd.,
400
vdcw
250
mrnf.,
500
vdcw
0.001
mfd.,
500
vdcw
0.1
mfd.,
400
vdcw
2
mi
.
.,
500
vdcw
0.
1
mfd.,
400
vdcw
r
0.1
mfd., 400
vdcw
0.1
mfd.,
400
vdcw
40
mfd.,
200
vdcw
50
mmf.,
500
vdcw
0.1
mfd.,
600
vdcw
8+8
mfd.,
475
vdcw
6
to
85
mmf.
5
and
5
mmf.
5-30
mmf.
6-85
wolf.
6-85
mmf./sec.
Part
of
C-43
THE
NC-
2-40D
RECEIVER
R-
40
C-
33
0-311-43
C13
R-
44
7
R-
I1
C-114
R2
C-3
T
c_32
C-
2
R-14
R8
R-30
j
G.4
5-6
R_28
C-94:
1
G-
I2
C-
17
R-41
R-
I 0
R-45
R-42
G-36
G-15
C-
I6
R-
17
C-
I8
R-9
C-30
R-
I 6
R-33
G-19
R-
I5
G-22
PHONO '
R-18
I
G-23
C-24
R-
2I
R-24
R-22 .
C-
I0
R-36
R-35
C-20
C-
2I
R-20
C-
3I
C-11
R-23
R-6 C-8
JACK
I
ST.
R.
AMP
1ST.
OET.
(COW.)
H.F
OSC.
R-27
R-25
R-6
s-8
-
C-7
R-3
R-4
T-
I
--
C-5
R-5
C-35
C-34
C-38
1
--
-
re\
Lri
R-38
J r
-eY
. ..
Alt
z,
meillilg
C-26
iIIÍIIÍI
R-37
i111i1i1,11
C-25
=
--...rt--...
ARM -
R-7
Fr
- t
i.
: 1
Lk
,
--PHONE
R-
3I
1
C-28
I
R-32
C-27
R-29
Fig. No.,
4.,
Bottom
view
of
Receiver
with
(
bit
Carriage
Removed
\--1'
• 1-
fr
crs
Tin
;
jg
rmtemitu.jil
!4
W41
14-
14
4
BAND
G
64
C-63
C-50
C-51
C-55
C-58
C
53
C-52
C
54
--
C-56
— C
57
edit*
I
Fig.
No.
5
Bottom
View
of
Receiver with
Coil
Carriage
Cover
Removed
15
16
THE
NC-
240D
1-
1ECEnER
SEI
MON
6.
PARTS
LIST
(
Continued)
Srmbol
Function
l'vm
,
Rating
CAPACITORS
IIiintinued)
C-
43B
T-2
Secondary
Tuning
Air
Part of C-43
C-44
Not
Used
C-
45
T-
3
Tuning
Air
6-85
rmd./sec.
C-
45A
T-3
Primary
Tuning .
Air
Part
of C-45
C-
45B
T-3
Secondary
Tuning
Air
Part
of C-45
G-46
Not
Used
C-
47
T-
4
Tuning .
Air
6-85
nrnf.
C-48
C.W.
Osc.
Control
Kir
1-10
mmf.
G-49
C. W.
Osc.
Compensating
Ceramic
10
mmf.,
500
vdcw
C-50
Gen.
Coverage
P.
F.
Amp.
Trimmer,
All
Bands •
Air
C-51
Gen.
Coverage
1st ['
et.
Trimer,
All
Bands
Air
C-52
Gen.
Coverage
H.
F.
Osc.
Trimmer,
All
Bands
Air
C-53
A,
13,
C,
D
Bands
Bandspread
H.
F.
Osc.
Air See
Note
No.
2
Trimer
C-54
A,
B,
C,
D
Bands
Bandspread
H.
F.
Osc.
Ceramic
2.5
to
6
rrrnf.
Padder
C-55
A
Band
Gen.
Gal/.
H.
F.
Osc.
Padder
Mica
750
mmf.,
500
vdcw
B
Band
Gen.
Coy.
H.
F.
Osc.
Padder
Mica
0.003
mfd., 500
vdcw
C
Band
Gen.
Cov.
H.
F.
Osc.
Padder
Mica
0.0017
mfd.,
500
vdcw
D
Band
Gen.
Cov.
Fl.
F.
Osc.
Padder
Mica
900
mmf.,
500
vdcw
F.,
Band
Gen. Cov.
Ft.
F'.
Osc.
Padder
Ceramic
500
mmf.,
500
vdcw
F
Band
Gen.
Cov.
H. F.
Osc.
Padder
Ceramic
250
mmf.,
500
vdcw
C-56
A
Band bandspread
H.
F.
Osc.
Padder
Ceramic
29
mmf.,
500
vdcw
B
Band
Bandspread
H. F.
Osc.
Padder
Ceramic
12
mf.,
500
vdcw
C
Band
Bandspread
H.
F.
Osc.
Padder
Ceramic
18
nrnf.,
500
vdcw
D
Band
Bandspread
H.
F.
Osc.
Padder
Ceramic
35 mmf.,
500
vdcw
C-57
A,B,C
Bands
Pandspread
H.F.
Osc.
Ceramic
10
mmf.,
500
vdcw
Fixed
Trimer
C-58
A
Band
General
Coverage
H.
F.
Osc.
Ceramic
29
mmf.,
500
vdcw
Feedback
Compensating
C-59
A, B, C,
D
Bands
1st ['
et.
Bandspread
Air
Trimmer
C-60
A
band,
1st
Detector
Bandspread
Padder.
Ceramic
38
mmf., 500
vdcw
B
band,
1st
Detector
Bandspread
Padder.
Ceramic
15.
5
mmf.,
500
vdcw
C
Band,
1st
Detector
Bandspread
Padder.
Ceramic
21
mmf.,
500
vdcw
D
Band,
1st
Detector
Bandspread
Padder.
Ceramic
38.5
mmf.,
500
vdcw
C-61
A
Band
1st
Detector
Gen.
Coverage
Ceramic
16
rrinf.,
500
vdcw
Coupling
C-62
A, P, C,
D
Bands
B.
F.
Amp.
Bandspread
Air
Trimmer
C-63
A
Band
R.
F.
M.
Bandspread
Padder
Ceramic
38
mnf.,
500
vdcw
B
Band
B.
F.
Amp.
Bandspread
Padder
Ceramic
15.
5
rrrnf.,
500
vdcw
C
Band
ELF. Amp.
Bandspread
Padder
Ceramic
21
mmf.,
5C0
vdcw
D
Band
B.
F.
Amp.
Bandspread
Padder
Ceramic
38.5
mmf.,
500
vdcw
THE
NC-
2-101)
HECF:1‘
17
PARTS
LIST
(
Continued)
SECTION
O.
S.
‘•
In
bol
Fit
net
ion
T
vin
,
Rating
I '
A
PM '
ITORS
ge'ontinued,
C-64
C-65
C-66
C-67
A
Band
Gen. Coy.
R.
F.
Amp.
Padder
Crystal
Filter Bridge
Crystal
Filter
Bridge
Phasing
Compensating
Mica
Ceramic
Ceramic
Mica
900
mmf.,
500
vdcw
50
mmf.,
500
vdcw
50
runf.,
500
vdcw
5-30
mnif.
RESISTORS
R-1
R-2
B-3
B-4
B-5
R-6
R-7
R-8
B-9
R-10
R-11
R-14
B-15
R-16
B-17
F-18
B-19
R-20
B-21
B-22
B-23
B-24
R-25
R-26
B-27
B-28
R-29
B-30
R-31
R-32
R-33
R-34
R-35
R-36
B-37
B-38
Fi
-
39
B-40
R.
F.
Grid
Filter
R.
F.
Cathode
Bias
1st
Det.
Cathode
Bias
1st
Det.
Screen
Bleeder
1st
Det.
Screen
Dropping
1st
Det.
Plate
Filter
1st
I.
F.
Grid
Filter
1st
I.
F.
Cathode
Bias
1st
I.
F.
Plate
Filter
Sec.
I.
F.
Grid
Filter
Sec.
I.
F.
Cathode
Bias
Not
Used
Not
Used
Sec.
Det.
Plate
Filter ....
Sec. Det.
I.
F.
Filter
Sec.
Det.
Load
Limiter
Input
Limiter
Output .
Tone
Control
A.
F.
Gain
Control
Inv.-
Audio
Cathode
Bias
Inverter
Grid
1st
Audio
Plate
1st
Audio
Plate
Output Grid
Output
Grid
Inv.
Feedback
Coupling
Output
Cathode
Bias
R.
F.
Gain
Control
B. F.
Gain
Bleeder
H.
F.
Osc.
B+
Dropping
H.
F.
Osc.
Grid
Beat
Osc.
Plate
Filter ..
Feat
Osc.
Grid
Beat
Osc.
Screen
Bleeder
Beat
Osc.
Screen
Dropping
Pi-
Voltage Divider
B+Voltage
Divider
Not
Used
2nd
I.
F.
Plate
Filter
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Comp.
Var
Comp.
Var.
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
W.W.
Var.
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
470,000
Ohms,
1/2
w.
470
Ohms,
1/2
w.
220
Ohms,
1/2
w.
100,000
Ohms,
1/2
w.
47,000
Ohms,
1/2
w.
2,200
Ohms,
1/2
w.
22,000
Ohms,
1/2
w.
See
Note
No.
1,
1/2
w.
2,200 Ohms,
1/2
w.
470,000
Ohms,
1/2
w.
See
Note
No.
1,
1/2
w.
2,200
Ohms,
1/2
w.
4,700
Ohms,
1/2
w.
22,000
Ohms,
1/2
w.
100,000
Ohms,
1/2
w.
47,000
Ohms,
1/2
w.
500,000
Ohms,
1
w.
500,000
Ohms,
1
w.
1,000
Ohms,
1/2
w.
470,000
Ohms,
1/2
w.
47,000
Ohms,
1/2
w.
47,000
Ohms,
1/2
w.
220,000
Ohms,
1/2
w.
220,000
Ohms,
1/2
w.
220,000
Ohms,
1/2
w.
220
Ohms,
2
w.
10,000
Ohms,
1
1/2
w.
47,000
Ohms,
1/2
w.
47,000
Ohms,
1
w.
47,000
Ohms,
1/2
w.
220,000
Ohms,
1/2
w.
47,000
Ohms,
1/2
w.
100,000
Ohms,
1/2
w.
100,000
Ohms,
1/2
w.
22,000
Ohms,
2
w.
22,000
Ohms,
2
w.
i
1,000
Ohms,
1/2
w.
18
TH
E
\
C-2-401)
RECEIVER
SECTION
6.
PARTS
LIST
('
ontinued)
s,.„,1„,/
Function
Iii.
liwing
II
ESISTIIIIS
gtiintinued,
Fi
-
41
R-
42
R-43
R-44
R-45
R- 46
AVC
Plate
Filter
AVC
Plate
AVC
Voltage Divider
AVC
Cathode
Bias
AVC
Grid
Limiter
Con
trol
....
Fixed
Fixed
Fixed
Fixed
Fixed
W.W.
Var.
470,000
Ohms,
1/2
w.
15,000
Ohms,
1/2
w.
2,700 Ohms,
2
w.
560
Ohms,
2
w.
4,700,000
Ohms,
1/2
w.
10,000
Ohms,
1
1/2
w.
MISII'ELLAN
FM'S
CE
- 1
F-1
•
F-2
I-1
I-2
I-
3
J-1
J-2
L-1
L-2
M-1
P-
2
P-3
S-
1
S- 1A
S-
1B
S-
IC
S-
2
S-
2A
S-
2B
S-3
S-
4
S-5
T-1
1-2
T-
3
1-4
X-
l
X-2
Y-1
1st
I.
F.
lransformer
A.C.
Line
Fuse
A.C.
Line
Fuse
S-
Meter
Lamp
Dial
Lamp
Dial
Lamp
Phone
Jack
Pick-up
Jack
Power
Supply
Filter
Choke
Power
Supply
Filter
Choke
Signal
Strength
Meter
Dummy
Plug
for
AC
Operation
Battery
Connector
Plug
Control
Switch
C.W.
Osc.
Switch
AVC
Switch
S-
Meter
Switch
Power
Supply
Switch
AC
Switch
P +
Switch
Tone
Control
Switch
Selectivity
Control
Switch
T-1
Primary
Selection
Switch.
Power
Transformer
bid
I.
F.
Transformer
Det.
Input
Transformer
Beat
Osc.
Transformer
Audio
Output
Socket
Battery
Connector
Socket...
Crystal
Resonator
.
Air
Tuned
Glass
Encl.
Glass
bici.
No.
40
No.
47
No.
47
Multi-Ckt.
Multi-Ckt.
Potted
Potted
'S"
Scale
Molded
Molded
Rotary
SPS1
51
3
SI
PSI
Rotary
S3
ST
SPSI
Rotary
Rotary
Toggle
150
Watt
Air
Tuned
Air
Tuned
Kir
Tuned
Bakelite
Bakelite
Cuartz
2
An.,
250
Volt
1
Amp.,
250
Volt
6-8
V.,
O.
15
A.
6-8
V.,
0.15
A.
6-8
V.,
0.15
A.
For
1/4"
dia.
plug
For
1/4"
dia.
plug
17 h.,
100
ma.
17
h.,
100
ma.
0
to
1
ma.
7
Prong
7
Prong
Two
Gang
250
V.,
1
A.
Part
of
S-1
Part
of
S-1
Part
of
S-1
Two
Gang
250
V.,
1
A.
Part
of
S-2
Part
of
S-2
Part
of
13-19
2
Section,
Ganged
[PDT,
250
V.,
3
A.
115/230
V.,
60
cycle
455
kc.
455
kc.
455
kc.
5
Prong
7
Prong
455
kc.
Note
No.
1:-
Resistors
R-8
and
R-11
are
individually
chosen
to
meet
the
circuit
re-
quirements
of
each
receiver.
Note
No.
2: -
Gen.
Coverage
ti.,F.,Osc.,Padder,
E &
F
Bands.
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