Hallicrafters S-40 B User manual

installation
and
operating
instructions
for model S-40 B
radio receiver
94X586
750
the hallicrafters co.
MANUFACTURERS OF RADIO AND ELECTRONIC EQUIPMENT, CHICAGO 21, U.S. A.

Figure 1. Radio Receiver Model S- 40B. BU. front view.

A A
G33
Si
BAND SWITCH I- I IS SHOWN IN
POSITION FOR BAND 4.
NOTE
RESISTANCE VALUES ARE IN » 4,10CA CAPACITOR
RELUES ARE IN NYE, PAPER CAPACITOR VALUES
ARE IN DECIMAL EQUIVALENTS OF MFQ4 ELECTROLYTIC
CAPACITOR VALUES ARE IN MF
/ DENOTES MECHANICAL ° MOM
e
G62
t.t
SO2
STANDBY SOCKET
2
VALUES tl TOLERENCES SHOWN ARE NOMINAL
is VARIATIONS MAY BE FOUND. IT IS RECOMMENDED
THAT THE VALUE OF ANY REPLACEMENT CORRESPOND
TO THE NOMINAL VALUE OF THE PART BEING REPLACED.
V2
6SA7
pi4-0 "0
U -7-0
!Xi r 014-
X V3
6SK7
%.3
100,000
R OB
SWITCH 545 SHOWN
IN POSITION I.
PL
105 - 125 60 AC
1. 2,000
V4
6SK7
/t27
•7,000
Vs VG
V2 6SC7 61(6— CT
44
I 270
R 121
>MST
1000 ,/ R
TO HEATERS
•
1LT
V5
V2 6SC7
LAST R SYMBOL R-67
LAST G SYMBOL C-64
.01
IS
1100 349 - A
4
TONE SWITCH ON)
I-4 C OP/
t—HICH
4— LOW
REPRESENTS TRANSFORMERS T-1 TO T-10

A A
SI
II
IA
BAND SWITCH 3-1 IS SHOWN IN
POSITION FOR BAND 4.
,0
C33
CS!
.25
NOTE.
RESISTANCE VALUES ARE IN > me micA CAPACITOR
VALUES ARE IN IMF, PAPER CAPACITOR VALUES
ARE IN DECIMAL EQUIVALENTS OF MFD., ELECTROLYTIC
CAPACITOR VALUES ARE IN MF
/ DENOTES MECHANICAL CIANGING
V
6SG7 R4
33
sl E
53
C62
SO?
STANDBY SOCKET
o
VALUES 8 TOLERENCES SHOWN ARF Nom1 , 4ILL
8 VARIATIONS MAY BE FOUND. IT IS RECOMMENDED
THAT THE VALUE OF ANY REPLACEMENT CORRESPOND
TO THE NOMINAL VALUE OF THE PART BEING REPLACED.
riioi4 P4 C ro
I-
V
2 3
6SA7 65K7
Re
10,000
t 0.
,I 1 . 1:7c1
R64
330
m.•
1 28 01
100,300 $
R 58 e
c s4
DI
99 :7C ,, $ 48 SHOWN
IN POSITION I
Th
R 66
47,000
I.
R67
0,000
T 16
PL,
105 - 125 60 AC
•
. 03 I
It,000
4 or
•
j
1.4
65K7
-2 -• C50
, 30 0I
C38
V5 V6
1/2 6 SC7 6K6-GT
C.41
I 170
TO HEATERS
6116
I.
W
1300
•
51
TOUPD
V5
1/2 6SC7
LAST R SYMBOL R-67
LAST C SYMBOL C-64
•70
./$0t 11531 1
01
090349 -A
•
TONE SWITCR ( 910,0
I- A C OPT
t-RIC04
3- MEDIUM
4- LOW
REPRESENTS TRANSFORMERS T4 TO T-10

ERRATA SHEET FOR S- 40B
After printing this manual a circuit improvement was made by
adding Resistor R-68 to the Oscillator Circuit as illustrated
below.
26 , z!,
T7
IMO
"MO
Tg
R30
25
10
24
D
t
017
.01
1E ---
9281408
94X697

the hallicrafters co.
SERVICE BULLETIN FOR MODEL S- 40B
GENERAL
Tubes Seven plus rectifier
Speaker 5- inch PM
Speaker V.C. Impedance.
Headset Output
Antenna
Tuning
Tuning Range
3.2 ohms
Low Impedance
Provision for external antenna
Manual
Band Selector Frequency
Position Range
1. 540 kc - 1680 kc
2. 1680 kc - 5.4 mc
3. 5.3 mc - 15.5 mc
4. 15.5 mc - 44 mc
Intermediate Frequency . 455 kc.
Power Supply Standard Model 105-125 V. 60
cycles AC
Universal Model 105-250 V.
25/135 cycles AC
Power Consumption . . . 75 Watts
RESTRINGING DIAL CORD
To restring the general coverage tuning dial cord, cut an
18- inch length of 30 lb. test dial cord and tie one end to the
tension spring of the main tuning capacitor drive pulley at
position " 1" on the diagram. Follow the numbers " 1" through
"4", and at position " 4" stretch the tension spring and tie the
cord securely.
To restring the band spread tuning dial cord cut a 36- inch
length of dial cord and follow the procedure as above, starting
at position " A" on the diagram. Note that the tuning drive
shafts are wrapped with two and a fraction turns of dial cord
for proper traction.
REPLACING LAMPS
Refer to Fig. 7 for the location of the two dial lamps used in
the receiver. To gain access to defective lamps, reach in
through cabinet cover and unclip the dial lamp sockets. The
TWO LOOPS THRU
H FLANGE HOLES At E.
NOTE PULLEY POSIT IONS
SHOWN FOR MAR.
GANG CAPACITY.
Fié 1. Dial cable strtnétné procedure
SENSITIVITY
CONTROL
.7 /
1050
FORM 91 IX587
RUN NO. I
SEE CHASS IS
STAMP
SI ANDSY
RECEIVE
SWITCH
SAND TUNING VOLUME A.V.C. CW/AM NOISE BANDSPREPD TONE PITCH
SELECTOR CONTROL CONTROL SWITCH SWITCH LIMITER TUNING CONTROL CONTROL
SWITCH
92%1840
sockets may then be brought out into the open to change the
defective lamp. Replace lamps with 6-8 V. Mazda # 44 ( Blue
bead) lamps or equivalent.
ALIGNMENT PROCEDURE
For I- F amplifier alignment it will be necessary to remove
the receiver chassis from the cabinet. The chassis is held in
the cabinet by three screws along both the bottom edge of the
front panel and the rear of the cabinet, and two screws on
either side of the front panel.
NOTE - R- F alignment should be accomplished through the
holes provided in the cabinet bottom as the oscillator calibra-
tion will be effected slightly by changes in the capacity between
the cabinet bottom and the r- f coils and wiring.
Before starting the alignment procedure, check the position
of the general coverage dial index marker on the low frequency
end of the range and the bandspread dial on zero position. The
general coverage condenser should index at max. capacity, and
the bandspread condenser at min. capacity.
The standard RMA dummy antenna mentioned in the align-
ment chart consists of a 200 mmf. condenser in series with a
20 oh r- f choke which is shunted by a 400 minf con,denser in
series with a 400 ohm carbon resistor.
Set the following controls before alignment.
SENSITIVITY Set at Maximum
VOLUME Set at maximum
AVC switch Set at OFF
BAND SPREAD Set at zero
CW/AM Set at AM ( See Step 2)
NOISE LIMITER Set at OFF
STANDBY RECEIVE Set at RECEIVE
TONE SWITCH Set at HIGH
For the settings lthe remaining controls, see alignment chart.

ALIGNMENT CHART
Signal Signal Band Receiver
Dummy Generator Generator Switch Dial
Step Antenna Coupling Frequency Setting Setting Adjust
Remarks
1 None Stator plates in center 455 kc
section of tuning gang.
"1"
1000 kc Sl,S2,S3 Maximum audio output at
S4,S5,S6 speaker voice coil. Use just
enough signal generator out-
put to obtain a 50 MW signal
level.
2 None See step 1
455 kc
(No modulation)
"1"
1000 kc S7 With the CW/AM switch set
at CW, remove the pitch
control knob and adjust Si
for zero beat. Replace the
knobwith the dot in the cent-
er position.
3 Std RMA " Al" on antenna strip.
dummy Jumper connected be-
tween " A2" and " G".
4 Std RMA See step 3
dummy
38 mc
1,411
36 mc * A, B, C Maximum output as in step 1
18 mc 18 mc * S8,S9,S10
14 mc " 3" 14 mc * D, E, F Maximum output as in step 1
10 mc 10 mc * S11,S12,S13
5 Std RMA See step 3
dummy
5 mc " 2" 5 mc * G. H, I Maximum output as in step 1
1.8 mc 1.8 mc * S14
6 Std RMA See step 3 1500 kc
dummy
600 kc
1500 kc * J, K, L Maximum output as in step 1
600 kc * M
*Note - Calibration adjustments.
92D1132
Fié. 2. Top view, alignment points

A, A o
IA
C33
BAND SWITCH S-1 IS SHOWN IN
POSITION FOR BAND 4.
C61
.25
NOTE
RESISTANCE VALUES ARE IN OHMS,MICA CAPACITOR
VALUES ARE IN MMF, PAPER CAPACITOR VALUES
ARE IN DECIMAL EQUIVALENTS OF MEO; ELECTROLYTIC
CAPACITOR VALUES ARE IN MED.
/ DENOTES MECHANICAL GANGING
(o.nx
entlà;.)
C•
(
Codoect 0 e 2 21rein _
zo a qeyvl :i I ii.taie en flet all .,
i
.i. .
VI V2 V3
6SG7 R4 6SA7 6SK7
33
s, SWITCH
STANDBY
SI E
23
0 62
Clo
T4 y
A
O
-{ - }> S- TANDBY SOCKET
VALUES a TOLERENCES SHOWN ARE NOMINAL
B VARIATIONS MAY BE FOUND. IT IS RECOMMENDED
THAT THE VALUE OF ANY REPLACEMENT CORRESPOND
TO THE NOMINAL VALUE OF THE PART BEING REPLACED.
25
32
27
R 8
0-W , Nr•
10000
E.
I i
/ • •
IC IS
•-• ,
L _ _ J
100,000 4
R SI3
REPRESENTS TRANSFORMERS TO T- I0
6
C52
02
600 y1, 11•7.
R66
•7.000 5
1 16
5 413
105 - 125 60 ,‘J AC
.7 -" D
=13
0
- J
3,000
1 w
,1 tec - #• 6- fe` t
V4
6SK7
-DI
7
47,000
V5 V6
V2 6SG7
0 44 6K6-GT
170
C 50
=30 . 0 /
C38
41.0126
TO HEATERS
6116
VVVY-A-43
w R 63
LM,
10
R2,
J2.51
INFO
V5
1/2 6SC7
470
LAST R SYMBOL R-67
LAST C SYMBOL C-64
Fié. 8. Schematic dlaéram
SWITCH S 4B SHOWN
IN POSITION I
S 4A
36C t!
.01
T 15
890349-A
TONE SWITCH ( 3W 4/
- • C OFF
2- HIGH
3- MEDIUM
4- LOW
"1".
O
12„
tie
-T*
k
a Q
1
••• 1'
6 . e0ie* t
F.1. tt.‘tst
get3 1/1
c,,

'— '1••••111%
o
o
o
6K6 - GT
92 Bete -
1, 10. 7. view. Icration Qf tubes and , flal lamps

o
i==\
S3
0*
O 0
0
o o
eh.
S9
SLY
050 CO
o
o
o
o
So S13 00°
0
o o
o
o o
O 0
o
O o
o
o
A
o
o
D
000
0 0
A
O 0
.0.
S14
H
G
ANT.
MIXER
PITCH CONTROL
KNOB
11 ,, tfnM ' iPb', allesnment Doints
92 DI133
Fie. 4. Ton view, component location

T1
C56
C44
R28 c,
R22
R34
R29 R
R23
C48
R24
C47
C64
T1
C55
C57
R63 R32 SQ6 R IO C39 C41 R18 C63 R27 C35 R67 R9 C52 R66 C58 C31 C9 R2 RI C33 CI R31 Rd C12 SI AB
C10 C2 Cd C3
RI, Cg R5 Ti 14 R65 12 T3
C53 J1 R62
C54 S6 C 4? , T 15 R61 1;2 6 ,:,
I tyà
RI5 R59 I I I C16 T7 C23
42 R25 S4 AB C59 R14 53 RI2 R58 C32 S5 Rg C28 R64 52 R21 R20 R7 C17 C18 R35 C19 SI EF R30 R3 C61
92 X 1127
C13
C14
Cl,
T5
C15
SlCD
C62 C 29 R 26
T10 C 25
T8 C20
C21
C22
C24
Fi0. 5. Bottom view, component location

SERVICE PARTS LIST
Ref. No.
C-1,2.12,
13,19
C-3
C-4,15,22
C-7
C-8.32.35,
58,59.60
C-9,28
C-10
C-11
C-14,21
C-16
C-17,53
C-18
C-20
C-25
C-23
C-24
C-27,53,51
C-29.33
C-31,43
C-38
C-39
C-41,42
C-44,55
C-45.48,52,
63
C-47
C-54
C-56
C-57
C-61
C-62
C-64
R-1,62
R-2
R-3
R-4,31
R-5
R-6,26
R-7
R-8
R-9
R-10
R-11,18,65
R-12,59
R-14
R-15,29,58
R-20
R-21
R-22
R-23,61
R-24
R-25
R-27,66
R-28
R-30
R-32
R-33
R-34
R-35
R-60,67
R-63
R-64
Description
CONDENSERS
Trimmer, adjustable. part of
transformers T-1,2.4,5 and 7
Trimmer, adjustable, part of
transformer T-3
Trimmer, adjustable
Tuning capacitor, 3 sections ganged
.05 mfd. 200 V., tubular
.05 mfd. 600 V., tubular
22 mmf. 500 V., ceramic
15 mmf. 500 V., ceramic
Trimmer, adjustable, part of
transformers T-6 and 9
390 mmf. 500 V., mica
.01 mfd. 600 V., tubular
68 mmf.. 500 V., ceramic
Trimmer, adjustable, part of
transformer T-8
Padder. adjustable. part of
transformer T-10
3000 mmf. 500 V., mica
1500 mmf. 500 V., mica
30-10-10 mfd. 450 V.,
electrolytic
220 mmf. 500 V., mica
.02 mfd. 200 V., tubular
2 mmf., twisted wire gimmick
.1 mfd. 600 V., tubular
47 mmf. 500 V., mica
270 mmf. 500 V., mica
.02 mfd. 600 V.. tubular
.002 mfd. 1000 V.. tubular
470 minf. 500 V., mica
.01 mfd. 600 V.. molded paper
1000 mmf. 500 V., mica
.25 mfd. 200 V., tubular
2.2 mmf. 500 V., bakelite
10 mfd. 25 V.. electrolytic
RESISTORS
1 megohm 1/2 watt, carbon
120 ohms 1/2 watt, carbon
10,000 ohms, SENSITIVITY
control
22 ohms 1/2 watt, carbon
39,000 ohms 1 watt, carbon
6800 ohms 1 watt, carbon
18,000 ohms 1/2 watt, carbon
10,000 ohms 2 watts, carbon
470 ohms 1/2 watt, carbon
12,000 ohms 4 watts, carbon
1000 ohms 1/2 watt, carbon
2.2 megohms 1/2 watt, carbon
47,000 ohms 1/2 watt, carbon
100,000 ohms 1/2 watt, carbon
1/2 megohm , VOLUME control
150 ohms 1/2 watt, carbon
270,00i) ohms 1/2 watt, carbon
470,000 ohms 1/2 watt, carbon
680 ohms 1 watt, carbon
15,000 ohms 1 watt, carbon
47,000 ohms 1 watt, carbon
22,000 ohms 1/2 watt, carbon
10 ohms 1/4 watt, carbon
1500 ohms 10 watts, WW
15 megohms 1/4 watt, carbon
10,000 ohms 1/2 watt, carbon
27 ohms 1/4 watt, carbon
330,000 ohms 1/2 watt, carbon
6.8 ohms 1 watt, carbon
330 ohms 1/2 watt, carbon
Hallicrafters
Part Number
44A149
44A389
44A191
48C240- B
46AU503.1
46AY503J
47X21UK220M
47X21UK150M
44A147
4'7X20B391K
46AY103J
47X25UK680K
44A148
44A188
47X30C302K
47X30C 152J
45A062
47X20B221K
46AU203J
46AY104J
47X20B470M
47X20B271K
46AY203J
46A104
47X20B471J
46AC1031
47X25B102M
46AT254J
47A160-4
45A121
23X20X105M
23X20X121K
25B590
23X20X220M
23X30X393K
23X30X682K
23X20X183K
23X40X103K
23X20X471K
23X65CE123K
23X20X102K
23X20X225M
23X20X473M
23X20X104M
25A534
23X20X151M
23X20X274K
23X20X474M
23X30X681K
23X30X153M
23X30X473K
23X20X223M
23X10X100M
24BG152E
23X10X156M
23X20X103M
23X10X270K
23X20X334K
23X30X068K
23X20X331K
Ref. No.
T-1
T-2
T-3
T-4
T-5
T-6
T-7
T-8
T-9
T-10
T-11,12
T-13
T-14
T-15
T-16
*T-16
Description
TRANSFORMERS AND COILS
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
Transformer.
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
Transformer,
antenna stage, band 4
antenna stage, band 3
antenna stage, band 1 and
mixer stage, band 4
mixer stage, band 3
mixer stage, band 1 and 2
oscillator stage, band 4
oscillator stage, band 3
oscillator stage, band 2
oscillator stage, band 1
1st and 2nd IF stages
detector stage
audio output
BFO
power
power ( Universal)
SWITCHES
S-1 Bandswitch, wafer, antenna stage
Bandswitch, wafer, mixer stage
Bandswitch. wafer, oscillator stage
Bandswitch, shaft
S-2,3. Switch, toggle, S.P.S.T., A.V.C., A.N.L.,
5,6 CW-AM, and STANDBY- RECEIVE
S-4 Switch, PWR-TONE control
PLUGS AND SOCKETS
J-1 Jack, headset
PL- 1 Line cord
SO- 6 Socket, standby
Socket, octal ( tube)
Socket, dial light, general coverage dial
Socket, dial light, bandspread dial
TUBES, RECTIFIERS AND LAMPS
V-1 Type 6SG7, r- f amplifier
V-2 Type 6SA7, mixer
V-3,4 Type 6SK7, 1st and 2nd i-f amplifiers
V-5 Type 6SC7, B.F.O. and audio amplifier
V-6 Type 6K6GT. audio power amplifier
V-7 Type 6H6, A.N.L. and detector
V-8 Type 5Y3GT, rectifier
LM- 1,2 Lamp, dial light, Mazda * 44
MISCELLANEOUS
TS- 1 Terminal strip, antenna
Lock, line cord
Spring, retainer ( Bandspread, and
main tuning drive shaft)
Dial cord
Spring, dial cord
Dial. bandspread
Dial, general coverage
Glass, general coverage dial
Window, bandspread
LS- 1 Speaker, P.M. ( 5- inch)
Knob, PITCH CONTROL
Knob, SENSITIVITY, VOLUME and
TONE
Knob, TUNING and BANDSPREAD
Knob, BAND SELECTOR
Foot, rubber
* Used on Universal Model S-40BU only.
Hallicrafters
Part Number
51B783
51B782
2 51B1241
51B787
51B786
51B1240
51B791
51B913
51B789
51B912
50C243
50C242
55B093
54B044
52A209
52C210
60B389
62B039
62B044
60B392
60A138
60A225
36A002
87B1573
10A015
6A035
86A070
86B049
90X6SG7
90X6SA7
90X6SK7
90X6SC 7
90X6K6GT
90X6H6
90X5Y3GT
39A003
88A032
76A397
75A062
38A001
75A012
83B372
83C240
22B199
22A307
85B050
12A058
15A04fÇ,
15A047
15A266
16A007

I GO/. SeTZM II. CV/ POSITION
V-8
520.4 - j - V-4 __ J
E
F- 12-
NOTES -
n
SOCKET vIE•5 ARE 130 , TOM ' HEWS
2 ALL VOLTAGES ARE MEASURED bET*E76 TUBE soc8F7 TER•885..5 855 ,,, 855,5 WITH zE•5 958, , 8,5,
5 LINE VOLTAGE Y AG
• ALL VOLTAGES ARE GO UNLESS CIRERA SE SKI:FI( D
5
oc VOLTAGES SHOWN A(A7 MEASURED WITH AR LECTRONIC VOLTMETER
6 ' NC . NO CONNECTION • OJAGE SHOWN FOR THIS TERMINAL ONLY WHEN TERMINAL IS USED AS A TIE LuG)
7 • 5R- NC? READABLE , I7F AGING GENERAL," MEANINGLE SS)
O SPACE PROVIDED FOR SERVICE mE"ERREADIRGS
FRONT APROR
130" 'DM oF CHASSIS
Fie. 6. Take socket voltnée chart
1.609,

INSTALLATION AND OPERATING
INSTRUCTIONS
FOR
RADIO RECEIVER MODEL S- 40B, BU
Your receiver, when properly installed, is capable of outstanding performance. Read the in-
stallation and operating instructions carefully as they are provided to insure the maximum
satisfaction from your receiver.
GENERAL: - The S- 40B receiver is a table model superheterodyne capable of receiving stand-
ard broadcast and foreign or domestic short wave stations over four frequency ranges with
continuous coverage from 540 Kc to 43 Mc. A bandswitch is provided to select among the four
ranges of reception which are indicated on the colorful and attractively illuminated main tuning
dial scale. The amateur bands as well as foreign station locations are also clearly indicated
on the main tuning dial scale for convenient reference. Appearing on the main tuning dial is
also a logging scale which is used as a reference in logging radio stations of special interest.
Many special features are provided to improve reception including bandspread tuning, auto-
matic noise limiter and automatic volume control. Provision is made for the optional use of a
headset. A beat frequency oscillator is provided for code reception. This feature is especially
useful to the radio amateur and code enthusiast.
The S40B receiver is designed to operate from a 105 to 125- volt, a- c, 50/60 cycle source and
requires 75 watts of power for operation. The S40BU receiver is designed to operate from a
110 to 250 volt a- c, 25 to 60 cycle source and requires 75 watts of power for operation. A
switch is located on top of the transformer for adjusting the transformer to the proper voltage
source. Connection to the power source is made by the two prong plug which is attached to the
six foot line cord extending from the rear of the cabinet.
The complete receiver is 9 inches high by 18-1/2 inches wide by 11 inches deep and weighs
28 pounds.
The maximum output of the receiver at the speaker is one watt with less than ten percent
distortion.
MECHANICAL DESCRIPTION: - The model S- 40B radio receiver is housed in an attractive well
ventilated aerodized sheet metal cabinet to minimize electrical interterence and provide me-
chanical strength. The full length aerodized top cover, mounted on a piano type hinge, pro-
vides a means of gaining access to all of the tubes, dial lamps, and primary i-f transformer
adjustments. Mixer, oscillator and secondary i-f adjustments may be made from the bottom of
the cabinet through the holes provided for this purpose under the notice card. Three small
holes on the bottom near the front of the cabinet provide access to the oscillator padder ad-
justments. All controls for tuning and operating are located on the front of the receiver.
Notice that some of the control markings are in red. This is to aid the novice in operating
the receiver.
ELECTRICAL DESCRIPTION: - The block diagram, Figure 2, illustrates the function of the
receiver circuits in a simple manner which is described as follows: radio signals are picked
up at the antenna and fed to the antenna coil of the r- f stage where the desired station signal is
selected by a resonant circuit and fed to the mixer- oscillator tube.
1

POWER
SUPPLY
RF
AMPLIFIER
MIXER a
OSCILLATOR
1ST IF
AMPLIFIER
2ND IF
AMPLIFIER
DETECTOR
AUTO. NOISE
LIMITER
1ST AUDIO
AMPLIFIER
BEAT FREO.
OSCILLATCR
11•••••11,
AUDIO
POWER
AMPLIFIER
92C10913
Figure 2. Radio Receiver Model S- 40B. BU, block diagram showing receiver circuits.
At the same time the oscillator section of the mixer - oscillator tube generates a local r- f
signal which is mixed with the selected incoming station signal. An intermediate frequency
signal of 455 kc ( kilocycles) is selected by the first i-f transformer and fed through two i-f
amplifier stages to the detector automatic noise limiter stage where it is demodulated. The
audio component of the i-f signal is amplified by one of the triode sections of the 1st audio-
beat frequency oscillator tube and then capacity coupled to the audio power output tube where
it is further amplified and fed to the speaker.
The a- v- c circuit is a conventional one which provides a uniform signal level when listening
to music or voice ( phone) broadcasts. It is in use with the AM/CW switch at the AM position.
The beat frequency oscillator stage operates in the CW position of the AM/CW switch and
provides an r- f signal at 455 kc ( kilocycles) which is fed to the detector stage to beat against
the i-f signal, thereby rendering code signals intelligible. The pitch of the code signal can be
varied by means of the CW-PITCH control which permits a variation from 0 to 1,000 cycles.
The automatic noise limiter circuit employs one diode of a duo- diode type tube ( 6H6), the other
diode being used as the detector stage.
A power rectifier stage provides a well filtered source of high voltage to the plate and screen
circuits.
INSTALLATION OF THE RECEIVER
1. As soon as the receiver has been unpacked, examine it for any apparent damage which
might have occurred in shipment. If any damages are found, file a claim IMMEDIATELY with
the transportation company. If purchased packed " over the counter" and any uefects or dam-
ages are apparent after the receiver has been unpacked, return it IMMEDIATELY to the
dealer. If purchased " unpacked" over the counter, examine carefully and thoroughly for any
possible defects, BEFORE ACCEPTANCE.
2. Fill out and immediately mail the record return card which is enclosed with these in-
structions.
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3. This receiver is equipped with rubber mounting feet for mounting on a table or other piece
of furniture. Do not mount this radio on a radiator or any area subject to heat or high
humidity.
4. An external antenna should be connected to the receiver as follows:
On the rear apron of the receiver chassis is located the antenna connector strip, marked Al,
A2 and G. Select one of the antenna systems described below and connect it to the strip as
directed.
An external ground connection is not essential to this receiver, but in some locations will help
to improve reception especially on the higher frequencies. If it is desired to use an external
ground, always eonnect it to the terminal marked " G" on the antenna terminal strip.
A. Single Wire Antenna: When using a single wire antenna installation, connect a jumper
between the antenna terminal A2 and G. Then connect a single wire of about 50 to 75 feet
(including lead-in) to terminal Al. Use # 14 gauge copper wire or heavier for best results.
Erect the antenna as high and free from surrounding objects as possible. This type of antenna
works well where the signal to noise ratio is relatively high and a more elaborate installation
is not practical. Refer to Fig. 3.
B. Doublet Antenna: This type
of antenna is recommended where
the receiving conditions are poor
or where maximum sensitivity is
required over a relatively narrow
range of frequencies. The lead-in
wires should be connected to term-
inals Al and A2. If a concentric
line with grounded outer conductor
is used, connect the inner conductor
to terminal Al, the outer conductor
to terminal A2 and connect a jum-
per between terminal A2 and G.
(1) To determine the proper length
of the doublet antenna in feet:
(a) Determine the frequency range
to which you wish to listen.
(b) Divide 468 by the frequency ( in
megacycles) of the high frequency
end of the range you selected. This
will give you the length in feet. Re-
fer to Fig. 4.
(2) To prepare the antenna for in-
stallation:
(a) Measure and cut the wire to the
length determined in step ( b) above.
Cut this length in half.
(b) Wrap and solder the two wires
of the lead-in to each of the quar-
ter- wave sections at the insulator
as shown in Figure 4.
JUMPER
TO GROUND CONNECTION
92A432
50 TO 100 FEET
Figure 3. Single Wire Antenna Installation.
TO GROUND CONNECTION
92A433
Figure 4. Doublet Antenna Installation.
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Keep in mind that this type of antenna is directional broadside to its length and should be so
orientated if maximum pick-up from a given direction is desired.
For reference to other types of antenna refer to the latest edition of the Radio Amateur's
A.R.R.L. Handbook, section on antennas. This book can be procured from most dealers of
radio amateur " ham" equipment.
PRE- OPERATIONAL CHECK - The following checkup on a newly installed receiver is recom-
mended before turning on the power for the first time.
(1) See that the tubes are securely seated in their sockets. Refer to Figure 7 for the proper
location of each tube.
(2) Check the pilot lamps located behind the dial escutcheons and see that they are securely in
place.
(3) Check all external connections. See that they are secure and make positive contact. Re-
member that an improvised installation gives improvised results.
OPERATION OF THE RECEIVER
EXPLANATION OF THE CONTROLS. — Scanning across the front of the receiver from left to
right, the control markings and an- explanation of- each is as follows:
NOTE: Some of the control markings are in RED. This is an added feature incorporated for
the
convenience of the listener who is not familiar with radio terminology as an aid in setting
the controls most used for the reception of standard broadcast stations.
Reference to Figure 6 will help the listener in becoming familiar with the use of the controls.
1. SENSITIVITY control. - This control regulates the sensitivity of the receiver. Turning
the control clockwise increases the sensitivity of the receiver.
2. BAND SELECTOR switch. - This switch selects the desired band or frequency range for
the listener. The frequencies covered by each band switch position are read directly from the
main tuning dial. Position # 1 ( in red) is the standard broadcast band. Each range has sufficient
overlap to provide continuous coverage over the overall tuning range of the receiver.
3. VOLUME control. - This control sets the audio level at the speaker and is to be set for
the level of volume most pleasing to the listener.
4. A. V. C. switch. - This switch, when set at " ON", provides a constant audio output level
over reasonable variations in signal strength at the antenna, i.e. it automatically controls the
sensitivity of the receiver when this circuit is in operation.
5. Main TUNING control. - This control tunes the receiver to the desired frequency of re-
ception which is read on the main tuning dial located to the left of the control. The outer scale
on the dial may be used for logging purposes which is described later on in these instructions.
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