Stromberg-Carlson 125 Dimension Guide
Engineering
Data
Stromberg-Carlson
No.
125
AC-DC
Radio
Receivers
STROMBERG-CARLSON
TELEPHONE
MANUFACTURING
COMPANY
Rochester,
New
York
ELECTRICAL
SPECIFICATIONS
Type
of
Circuit_
Tuning
Ranges_
Number
and
Types
of
Tubes_
Voltage
Rating_
Power
Frequency
(For
AC
Operation)
Input
Power
Rating_
Intermediate
Frequency_
-Superheterodyne
A—540
to
1500
Kc.;
B—1450
to
3500
Kc.;
C—5600
to
18,000
Kc.
_1
No.
6A8,1
No.
6K7,
1
No.
6Q7,
1
No.
43,
1
No.
25Z5
-105
to
125
Volts
-50-60
Cycles
-45
Watts
_465
Kilocycles
APPARATUS
SPECIFICATIONS
No.
125,--50
to
60
Cycles
(For
AC
Operation)-P-26052
Chassis
Assembly
CIRCUIT
DESCRIPTION
This
triple
range,
superheterodyne
receiver
has
five
tubes
and
may
be
operated
on
a
power
supply
circuit
of
either
alternating
or
direct
current
at
the
voltages
and
frequency
(for
A.
C.
operation)
specified
above.
The
various
tubes
are
used
in
this
receiver
as
follows:
One
No.
6A8
tube
functions
as
both
Oscillator
and
Modulator;
one
No.
6K7
tube
is
used
in
the
I.
F.
Amplifier;
the
No.
6Q7
tube
is
used
as
the
Demodulator,
A.
V.
C.,
and
Audio
Amplifier
tube.
The
No.
43
tube
is
used
in
the
Audio
Power
Output
stage,
and
the
No.
25Z5
tube
is
used
as
the
Rectifier
tube
for
the
receiver
“B”
voltage
supply.
NORMAL
VOLTAGE
READINGS
These
voltage
readings
are
obtained
by
measuring
between
the
various
tube
socket
contacts
and
the
heavy
bus
wire
with
the
tubes
in
their
respective
sockets.
The
receiver
is,
therefore,
in
operation
when
the
measure¬
ments
are
made.
The
heavy
bus
wire,
which
is
the
negative
side
of
the
grid
and
plate
voltages,
is
plainly
marked
on
the
schematic
and
wiring
diagram
shown
on
pages
three
and
five.
Figure
1,
shows
the
terminal
layout
of
the
sockets
with
the
proper
terminal
numbers.
Voltages
are
given
for
a
line
voltage
of
120
volts,
A.
C.
Allowance
should
be
made
for
the
difference
when
the
line
voltage
is
higher
or
lower.
IMPORTANT—If
the
receiver
is
operated
from
a
direct
current
power
supply
circuit,
the
various
volt¬
ages
measured
will
be
slightly
lower
than
those
listed
in
the
table
for
A.
C.
operation.
A
meter
having
a
resist¬
ance
of
1000
ohms
per
volt
should
be
used
for
measuring
the
D.
C.
voltages.
Voltage
values
shown
are
those
ob¬
tained
on
the
lowest
possible
scale
of
a
meter
having
the
following
ranges:
0-2.5,
0-10,
0-100,
0-250,
0-500,
0-1000
volts
except
when
an
asterisk
appears
after
any
given
voltage
value
in
which
case
the
1000
volt
scale
was
used.
When
the
receiver
is
being
operated
from
an
alternating
current
power
supply
circuit,
it
will
be
necessary
to
have
a
high
resistance
A.
C.
voltmeter
for
checking
the
A.
C.
voltages.
Tube
Circuit
Cap.
Terminals
of
Sockets
Heater
Voltages
Between
Heater
Terminals
Terminal
Numbers
Volts
1
2
3
4
5
6
7
8
6A8
Mod.—Osc.
—.02
125
0
+
97
+
60
—
7
+73
6.3
+1.3
2-7
6.3
6K7
I.
F.
Amp.
0
125
0
+
97
+
91
+
3
—
18
+3
2-7
6.3
6Q7
Dem.—A.V.C.
—Audio
0
0
0
+55*
0
0
—
6.2
+1
2-7
6.3
43
Audio
Output
—
43
+
90
+
96
0
+
12
18
—
—
1-6
24
25Z5
Rectifier
—
65
112
+102
+102
112
43
-—
—
■
1-6
22
Voltage
across
pilot
lamps—
8.2
volts
A.C.
voltages
are
indicated
by
italics;
when
the
receiver
is
operated
from
a
D.G,
power
supply,
D.C
voltages
will
be
obtained
in
place
of
the
A.C.
voltages.
Receiver
tuned
to
1000
kc.,
no
signal.
P-28429
Form
No.
1898
Issue
1
Printed
in
V.
6.
4.
2
ALIGNMENT
DATA
All
alignment
adjustments
are
accurately
made
at
the
factory
on
these
receivers
and
ordinarily
no
re¬
adjustments
are
necessary.
However,
should
it
become
necessary
to
make
any
readjustments,
this
alignment
procedure
should
be
carefully
followed.
In
making
any
alignment
adjustments
always
adjust
the
signal
generator’s
output
to
the
minimum
value
V
'g
id
3
®°
0<
^
£|
l
1
8
nmen
t
may
still
be
obtained.
Never
attempt
to
make
any
alignment
adjustments
using
a
strong
Figure
1
shows
the
location
of
all
the
aligning
capacitors
used
in
this
receiver.
Intermediate
Frequency
Adjustments
The
intermediate
frequency
used
in
these
receivers
is
465
kilocycles.
In
making
these
I.
F.
circuit
ad¬
justments
always
align
in
the
following
order:
1.
Secondary
of
2nd
I.
F.
Transformer
(Capacitor
C-10).
2.
Primary
of
2nd
I.
F.
Transformer
(Capacitor
(C-9).
3.
Secondary
of
1st
I.
F.
Transformer
(Capacitor
C-8).
4.
Primary
of
1st
I.
F.
Transformer
(Capacitor
C-7).
Radio
Frequency
Adjustments
The
adjustments
of
the
aligning
capacitors
used
in
the
radio
frequency
circuits
in
this
receiver
should
be
very
carefully
made
in
the
following
order
and
at
the
frequencies
specified
below:
1.
Oscillator’s
“C”
Band
Shunt
Aligner
at
17
Megacycles
(Capacitor
C-4).
2.
Antenna
“C”
Band
Shunt
Aligner
at
17
Megacycles
(Capacitor
C-l).
3.
Oscillator’s
“B”
Band
Shunt
Aligner
at
3.4
Megacycles
(Capacitor
C-5).
4.
Antenna
“B”
Band
Shunt
Aligner
at
3.4
Megacycles
(Capacitor
C-2).
5.
Oscillator’s
“A”
Band
Shunt
Aligner
at
1400
Kilocycles
(Capacitor
C-6).
6.
Antenna
“A”
Band
Shunt
Aligner
at
1400
Kilocycles
(Capacitor
C-3).
7.
Oscillator’s
“A”
Band
Series
Aligner
at
600
Kilocycles
(Capacitor
(36)
).
8.
Oscillator’s
“A”
Band
Shunt
Aligner
at
1400
Kilocycles
(Capacitor
C-6).
9.
Antenna
“A”
Band
Shunt
Aligner
at
1400
Kilocycles
(Capacitor
C-3).
REPLACEMENT
PARTS
Item
Number
Piece
Number
Part
2
25998
Bracket
Assembly
5
26057
Gang
Tuning
Condenser
6
26143
Dial
Assembly
8
26287
Dial
Lamp
13
26121
1st
I.
F.
Transformer
14
25506
2nd
I.
F.
Transformer
16
26133
Choke
Assembly
17
26135
Transformer,
Output
19
26162
Capacitor,
Electrolytic
25
Mf.
20
26163
Capacitor,
Electrolytic
40
Mf.
21
26164
Capacitor,
Electrolytic
4-4-12
Mf.
22
25481
Capacitor
.002
Mf.
23
25483
Capacitor
.1
Mf.
24
25483
Capacitor
.1
Mf.
25
25483
Capacitor
.1
Mf.
26
25150
Capacitor
.02
Mf.
27
25150
Capacitor
.02
Mf.
28
25150
Capacitor
.02
Mf.
29
25150
Capacitor
.02
Mf.
30
25150
Capacitor
.02
Mf.
31
25150
Capacitor
.02
Mf.
32
25150
Capacitor
.02
Mf.
33
25389
Capacitor
Assembly
.2
Mf.
34
24405
Capacitor
Assembly
.04
Mf.
35
24405
Capacitor
Assembly
.04
Mf.
36
26747
Capacitor,
Aligner
37
26778
Capacitor
.005
Mf.
38
25487
Capacitor
.001
Mf.
39
25487
Capacitor
.001
Mf.
40
25489
Capacitor
.00125
Mf.
41
25504
Capacitor
100
Mmf.
42
25504
Capacitor
100
Mmf.
43
25504
Capacitor
100
Mmf.
44
24559
Capacitor
100
Mmf.
48
25513
Coil
Assembly,
Wave
Trap
49
25814
Coil
Assembly,
Choke
50
25814
Coil
Assembly,
Choke
51
26362
Resistor
Type
"E”
.27
Megohms
62
26362
Resistor
Type
“E”
.27
Megohms
53
26362
Resistor
Type
“E”
.27
Megohms
54
26826
Resistor
Type
“E”
270
Ohms
55
26327
Resistor
Type
W
E”
330
Ohms
Item
Piece
Number
Number
Part
56
26327
Resistor
Type
“E”
330
Ohms
57
26353
Resistor
Type
“E”
47,000
Ohms
58
26353
Resistor
Type
“E”
47,000
Ohms
59
26369
Resistor
Type
*‘E”
1
Megohm
60
26369
Resistor
Type
"E”
1
Megohm
61
26345
Resistor
Type
“E"
10,000
Ohms
62
26345
Resistor
Type
“E”
10,000
Ohms
63
26345
Resistor
Type
**E”
10,000
Ohms
64
26357
Resistor
Type
“E”
.1
Megohm
65
V
26333
Resistor
Type
“E"
1,000
Ohms
67
26373
Resistor
Type
“E”
2.2
Megohms
68
26408
Resistor
Type
“C”
27,000
Ohms
69
26330
Resistor
Type
“E”
560
Ohms
70
26365
Resistor
Type
“E"
.47
Megohms
71
25911
Resistor
Type
“R”
50
Ohms
72
26127
Resistor,
“B”
Voltage
Divider
73
26252
Insulation
(For
Tone
Control)
74
26114
Potentiometer
(Volume
Control)
75
26061
Off-On
Switch—Tone
Control
77
25539
Tube
Socket,
8
Prong
78
22974
Tube
Socket,
6
Prong
85
24268
Cord,
Power
Supply
86
25564
Grid
Clip
Assembly
87
26053
Speaker
Assembly
105
26172
Range
Switch
106
25488
Capacitor
.002
Mf.
107
26113
Coil
Assembly,
Antenna
108
26157
Coil
Assembly,
Oscillator
109
26424
Dial
Damp
Socket
Assembly
111
25149
Capacitor
Assembly,
.01
Mf.
112
25488
Capacitor
.002
Mf.
113
26417
Capacitor
(Gimmick)
Piece
Number
26096
MISCELLANEOUS
PARTS
Part
Cone
Assembly
(For
P-26053
Speaker)
26296
Knob
(Used
on
Volume,
“Off-on-Tone*’
26297
and
Station
Selector
Controls)
3
Required
for
Each
Receiver
Knob
(For
Range
Switch)
1
Required
3
Fig.
4.
Wiring
Diagram
of
Chassis.
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