Hallicrafters Sx-100 mark ia User manual

Fig. 1.

Hallicrafters

SX-1

00

Receiver

SECTION

1.

GENERAL

Your new

Hallicrafters

SX-100

Selectable

Sideband

Receiver

is

precision

built

to

bring

you

the

finest

in

world-

wide

radio

reception.

This

fourteen-tube

dual

conversion

superheterodyne

receiver

tunes

from

538

to

1580

kilocycles

and

1. 72

to

34

megacycles,

with

calibrated

electrical

bandspread

provided

on

the

80, 40, 20,

15

, and

11-10

meter

amateur

bands.

You'll

hear

foreign

and

domestic

shortwave

broadcasts,

amateurs,

police

,

aircraft,

ships-at-

sea,

and

countless

other

exciting

distant

stations

. . .

as

well

as

all

your

favorite

programs

on

standard

broadcast

.

The

receiver

provides

for

the

reception

of

CW,

AM,

and

single-

sideband

signals

over

its

entire

tuning

range,

the

upper

or

lower

sideband

be-

ing

readily

selectable

by

means

of a

front

panel

control.

This

selectable

sideband

feature

not only

greatly

simplifies

tuning

of

signal-sideband

signals

but

is

also

useful

in

eliminating

heterodyne

interference

when

receiving

AM

signals.

Unlike

the

ordinary

dual-conversion

receiver,

your

SX-100

receiver

employs

dual

conversion

on

all

bands

.

.<\s

a

result,

images

are

practically

non-existent.

"Razor-sharp"

selectivity

is

made

possible

by

the

use

of an

adjustable

50.

5

kc

second

IF

with

four

high-Q,

permeability-tuned

circuits.

Receiver

selectivity

is

variable

in

five

steps

from

500

cycles

to

5

kc

at

6

db

down and

from

5

to

20

kc

at

60 db down.

Atuned

r-f

stage

assures

maximum

sensitivity

and a high

signal-to-noise

ratio

for

outstanding

reception

of weak

and

distant

signals.

A

manual

sensitivity

control

prevents

overloading

by

strong

signals

. An

antenna

trimmer

,

adjust-

able

from

the

front

panel,

permits

peaking

of

the

r-f

stage

to

compensate

for

loading

effects

of

various

antennas.

A

notch

filter

circuit

allows

rejection

of an

extremely

narrow

portion

of

the

IF

passband.

With

the

notch

filter,

an

inter-

fering

signal

can

easily

be

"notched

out".

The

position

and

the

degree

of

notch

rejection

are

adjustable

from

the

front

panel.

Outstanding

frequency

stability

is

achieved

by

the

use

of

ceramic

trimmers

and

coil

forms

in

the

1st

conversion

oscillator,

extensive

temperature

compensation,

voltage

regulation

of

all

oscillators,

and

the

use

of a

crystal-

controlled

2nd

conversion

oscillator

.

Tuning

is

accomplished

by a precIsIOn

gear

drive

tuning

mechanism

to

insure

extremely

close

calibration

and

accurate

resetability.

Smooth flywheel

tuning

affords

maximum

traverse

speed

and

operating

ease.

A 100

division

logging

scale

on

the

MAIN TUNING

ahd

BANDSPREAD knobs,

plus

a

hundredths

scale

on

the

tuning

dial

s,

assures

ease

and

accuracy

in

loggingand

relocating

stations

of

special

interest.

The

logging

number

is

the

logging

number

of

the

dial

plus

tl).e

number

on

the

knob

scale.

For

example;

if

the

main

tuning

dial

logging

scale

reads

12, and

the

MAIN TUNING

knob

scale

reads

25,

the

logging

number

is

1225. A

built-

in 100

kc

crystal

calibrator

provides

marker

signals

at

every

100

kc

on

the

dial

for

checking

calibration

accuracy.

A

trimmer

capacitor

,

accessible

from

the

top

of

the

chaSSiS,

p

'

~rmi

ts

adjustment

of

the

calibrating

oscillator

to

exactly

100 kc by

comparision

with

the

frequencies

transmitted

by

station

WWV.

An

automatic

series

noise

limiter

circuit,

controlled

by a

switch

on

the

front

panel,

reduces

interference

from

electrical

equipment, ignition

noise

, and

other

forms

of

pulse

type

noise.

-2-

An

"S"

meter

is

used

when

receiving

AM

signals

to

indicate

the

accuracy

of tuning and the

relative

strength

of

received

signals.

The

meter

is

calibrated

in

microvolts,

"s"

units

from

1

to

9,

and in

decibels

above

S9

to

+ 80 db.

The

Receive-Standby

switch

on

the

front

panel

silences

the

receiver

but

leaves

the

heater

and

plate

power

on to

provide

instant

reception

between

transmission

periods.

Provision

has

also

been

made

in

the

receiver

for

remote

receive-standby

control, and for

transmitter

switching

from

the

front

panel.

Audio output connectionsinclude

terminals

for

a

3.

2-ohm

speaker

and a 500/600-ohm output

for

line

or

speaker.

A

front

panel jack

for

headphones

is

also

provided

and

the

speaker

is

automatically

silenced

when

the

headphoneplug

is

inserted.

A phono input

jack

at

the

rear

of

the

receiver

permits

attachment

of a

record

player.

The

receiver

is

designed

to

operate

on 105

to

125 volt, 50/60 cycle

AC

current.

Provision

is

also

made

in

the

receiver

for

operation

from

an

external

DC

power

supply

or

batteries

in

areas

where

AC

power

is

not available.

SECTION

2.

INSTALLATION

2-1. UNPACKING

After unpacking

the

receiver,

examine

it

closely

for

damage which

may

have

occured

in

transit.

Should any

Signof

damage

be

apparent,

file

a

claim

immediately

with

the

carrier

stating

the

extent

of damage. Carefully check

all

shipping

labels

and

tags

for

instructions

before

removing

or

destroying

them.

2-2.

LOCATION

The

receiver

may

be

placed

in any

location

that

will

permit

free

air

circulation

through

the

ventilation

holes

and openings in

the

cabinet. Avoid

excessively

warm

locations

such

as

those

near

radiators

and heating vents.

The

external

speaker

may

be

located

in any convenient pOSition although

it

is

recommended

that

it

not be

placed

on top of

the

receiver

for

reasons

of ventilation.

2-3.

ANTEN

NAS

The

r-f

inputof

the

receiver

is

designed

for

operation

form

either

a

single-wire

antenna,

or

a

half-wave

doublet

or

other

tuned

antenna

with

transmission

line

impedances

from

52

to 600 ohms. Antenna connections

are

made

to a

three

terminal

strip

at

the

rear

of the

receiver

marked

"A1",

"A2",

and "G". Mounting holes

are

also

provided,

ad-

jacent

to

the

antenna

terminals,

for

installation

of an

AN

type SO-239 connector

for

coaxial cable

installations.

A. SINGLE WIRE ANTENNA

The

Simplest

antenna

and one which will

provide

satisfactory

results

throughout

the

entire

tuning

range

is

a conventional

single-wire

antenna.

In

most

localities,

good

results

can

be

obtained with

just

the

15-foot

length

of

antenna

wire

suppliedwith

the

receiver.

(See Fig.

2.)

Simply

attach

one end of

this

wire

to

terminal"

A1", and

"G",

and then

run

the

wire

about

the

room

in any con-

venient

manner.

If

the

receiver

is

operated

in a

steel

constructed

building

or

where

receiving

conditions

are

exceptionally

poor,

an

outside

antenna,

50

to

100

feet

long, may

be

necessary.

The

outside

antenna should

be

erected

as

high

as

possible

and kept

free

from

surround-

ingobjects. In

some

locations,

reception

may

be

improv-

ed

by

connecting a ground

wire

(ordinary

copper

wire)

from

terminal"

G"

to

a cold

water

pipe

or

outside

ground

rod. While

the

use

of an

outside

ground

rod

installed

in

accordance

with

Insurance

Underwriter's

Laboratories

requirements

is

adequate

protection

against

lightning, we

strongly

recommend

anadditional connection

to

the

near-

est

cold

water

pine

to

eliminate

any

shock

hazard.

B.

HALF·WAVE

DOUBLET

ANTENNA

For

top

performance,

especially

on

the

short-

wave and

amateur

bands,

the

use

of a

half-wave

doublet

or

other

type

of antennaemployinga

52

to

600-ohm

trans-

mission

line

is

recommended.

A

typical

doublet

antenna

installation

is

shown in Fig.

3.

The

double

antenna

should

be

cut

to

the

proper

length

for

the

most

used

fre-

-3-

9261391-C

Fig.

2. Single

Wire

Antenna

Fig

..

3.

Doublet Antenna Using

Twin-Lead

Transmission

Line

quency

or

band

of

frequencies.

The

overall

length

in

feet

of a

doublet

antenna

is

determined

by

the

following

formula:

468

Length

in

feet

=

Frequency

in

megacycles

The

doublet

antenna

is

directional

and

should

be

erected

with

its

entire

length

facing

a

desired

station

for

maximum

signal

pickup.

The

doublet

antenna

may

be

fed

with

either

a

balanced

or

unbalanced

transmission

line.

When

a

balanced

line

such

as

"twin-lead"

or

a

twisted

pair

is

used,

the

line

connects

to

terminals

"AI"

and

"A2"

and

the

jumper

link

between

"A2"

and

"G"

is

disconnected.

(See

Fig.

3.)

When

using

an

unbalanced

line

such

as

coaxial

cable,

the

inner

conductor

connects

to

terminal

"AI",

the

outer

metal

braid

connects

to

terminal

"A2",

and

the

jumper

link

connects

between

terminals

"A2"

and

"G".

A

ground

wire

may

improve

reception

when

using

an

unbalanced

type

line.

By

feeding

the

doublet

antenna

with

a

transmission

line

having

an

impedance

of 300

ohms,

a

broader

frequency

response

is

obtained

than

that

possible

with

a

50-75

ohm

line.

The

doublet

antenna

provides

optimum

performance

only

at

the

frequency

for

which

it

is

cut.

Therefore,

it

may

be

desirable

for

reception

on

frequencies

remote

from

the

antenna

frequency

to

utilize

the

antenna

as

a

single

wire

type.

This

is

accomplished

by

connecting

the

two

transmission

line

leads

together

and

connecting

them

to

terminal

"AI".

The

jumper

link

in

this

case

should

be

connected

between

terminals

"A2"

and

"G".

In

an

installation

where

the

receiver

is

used

in

conjunction

with

a

transmitter,

it

may

be

advantageous

to

use

the

same

antenna

for

receiving

as

for

transmitting.

This

is

especially

true

when

a

directive

antenna

is

used

since

the

directive

effects

and

power

gain

of the

transmitting

antenna

are

the

same

for

receivin&

as

for

transmitting.

Switching

of

the

antenna

from

the

transmitter

to

the

receiver

may

be

accomplished

with

a

double-pole,

double-throw

antenna

changeover

relay

or

knife

switch

connected

in

the

antenna

leads.

For

further

information

regarding

antennas,

refer

to

the

"Radio

Amateur's

Handbook"

or

the

"A.R.R.L.

Antenna

Book",

both

published

by

the

American

Radio

Relay

League,

West

Hartford,

Conn.,

U.S.A.

c=::=J c=::=J

c::=J c::=J

c::=J

2-4.

POWER

SOURCE

c=::=J c=::=J

c=::=J c=::=J c=::=J

c::=J c::=J

c::=J

c::=J c::=J

c::=J

c=::=J

c::=J

500

::~:CJ.

~

@

\

"s" METER ANTENNA

ADJUSTMENT INPUT

TERMINALS

Fig.

4.

Rear

View of

Receiver

c::=J

MOUNTING

roR

GO-AXIAL

GABLE

CONNECTOR

The

receiver

is

deSigned

to

operate

directly

on

105

to

125

volt,

50-60

cycle

AC

current.

Provision

has

also

been

made

in

the

receiver

for

operation

from

an

external

DC

power

source

for

portable

or

emergency

service.

in

areas

where

AC

power

is

not

available.

Connections

to

the

DC

source

are

made

through

the

DC

POWER

SOCKET

at

the

rear

of

the

receiver.

(See

Fig.

4.)

A.

AC

OPERATION

Insert

the

power

cord

into

any

convenient

AC

power

outlet

of

the

proper

rating.

If

in

doubt

about

your

power

source,

contact

your

local

power

company

before

plugging

in

the

reCeiver.

The

wrong

power

source

can

cause

serious

damage.

IMPORTANT:

The

receiver

will

not

operate

from

an

AC

source

unless

the

JUMPER

PLUG

is

inserted

in

the

DC

POWER

SOCKET. (See

Fig.

4.)

B.

DC OPERATION

The

receiver

may

be

operated

from

an

external

DC

source,

such

as

a

vibrator

power

supply

or

batteries

by

removing

the

JUMPER

PLUG

normally

located

in

the

DC

POWER

SOCKET.

at

the

rear

of

the

receiver

and

replacing

it

with

a

similar

octal

plug

wired

as

shown

in

Fig.

5.

This

plug

is

available

from

your

Hallicrafters

dealer

under

Part.

No. 35A003.

The

voltage

and

current

requirements

for

DC

operation

are

as

follows:

"B"

supply,

280

volts

at

105

ma;

"A"

supply,

6.3

volts

at

4.1

amps.

- 4 -

BA

TTERIES

2-5.

SPEAKER

+

+"A"

VIBRATOR

POWER

SUPPLY

?

6VOlTS

L:II +

Fig.

5.

Wiring

Diagram

for

DC

Operation

A+

A-

B-

B+

280

VOLTS

9281388-A

'

A

three-terminal

strip,

marked

"G",

"3.2"

and

"500",

is

provided

at

the

rear

of

the

receiver

for

connecting

the

external

speaker

that

is

required

with

the

receiver.

(See Fig. 4.)

Any

permanent

magnet

speaker

with

a

3.2-ohm

voice

coil

can/be

used

by

simply

connecting

the

two

leads

from

the

speaker

voice

coil

to

the

terminals

marked

"3.2"

and

"G".

If

it

is

desired

to

use

a

speaker

with

a

voice

coil

impedance

other

than

3.2

ohms,

a matChing

transformer

should

be

emplqyed

to

insure

optimum

performance.

The

transformer

should

be

mounted

on

or

near

the

speaker,

and

should

have a 5

watt

power

rating,

a

500-ohm

primary

impedance,

and a

secondary

impedance

to

match

the

impedance

of

the

speaker

voice

coil.

Connect

the

primary

of

the

transformer

to

the

terminals

marked

"500"

and

"G"

and

the

secondary

to

the

speaker

voice

coil

terminals.

\The

Hallicrafters

R-46B

and

R-47

speakers

are

both

designed

for

use

with

your

receiver.

Either

speaker

may

be

connected

to

the

terminals

marked

"3.

2"

and

"G'·.

2-6.

HEADPHONES

The

headphone

jack,

marked

PHONE,

is

located

on

the

front

panel

of

the

receiver

and

is

wired

so

that

the

speaker

is

automatically

silenced

when

the

headphones

are

plugged in.

The

headphone output

impedance's

not

critical,

and

any

commercial

low-impedance

headphones

ranging

from

50

ohms

to

5000

ohms

will

provide

satisfactory

performance.

TO

CATHODE

CIRCUITS

OF

RF

AMP

(VI)

.IS50

KC

IF

AMPl

V4),

~

50.5

KC

IF

AMP

(VS)

S02

I

SENSITIVITY!

R59

10K

-=

DC

POWER

SOCKET

RSO

330K

-)

S7A

1-7

IRECEIVE

-

STANDByl

S7B

=1

R=EC=E

IV-=E'--

S=TA""'N-"'D

B""y

I

-=

I

-=

'

I I

I '

L

____________________

,

-/

f

/

I ,

Fig.

6.

Schematic

Diagram

of

Sensitivity

and

Re

cei

ve-Standby

Cir

cuits

- 5 -

2-7.

RECORD

PLAYER

CONNECTIONS

A phono

jack

is

provided

at

the

rear

of

your

receiver

for

attaching

a

record

player.

(See

Fig.

4.)

Any

record

player

using

a

crystal

cartridge,

or

a

magnetic

cartridge

with

a

suitable

pre-amplifier,

will

provide

satisfactory

results.

For

phono

operation,

insert

the

pin-plug

from

the

record

player

or

pre-amplifier

into

the

phono

jack

and

set

the

SELECTIVITY

control

on

the

front

panel

at

"PHONO".

Adjust

the

VOLUME

control

for

the

desired

volume

level

and

set

the

RESPONSE

control'at

either

"NORMAL"

or

"TREBLE

CUT"

for

the

desired

tone.

The

remaining

controls

are

inoperative

and

will

have no

effect

on phono

operation.

2-8.

RELAY

AND

TRANSMITTER SWITCHING

One

half

of the

dpst

RECEIVE-STANDBY

switch

on

the

front

panel

connects

to

pins

2

and

5 of

the

DC POWER

SOCKET

at

the

rear

of

the

receiver,

and

is

available

for

transmitter

switching.

(See

Fig.

6.)

This

half

of

the

switch

is

in

the

open

position

when

the

RECEIVE-STANDBY

switch

is

set

at

"STANDBY" and

closed

when

set

at

"RECEIVE".

2-9.

REMOTE

RECEIVE-STANDBY SWITCH

The

receiver

may

be

disabled

from

a

remote

location

by

connecting

a

remote

spst

switch

between

pins

1 and 4 of

the

JUMPER

PLUG

located

in

the

DC POWER SOCKET

at

the

rear

of

the

receiver.

(See

Figs.

4

and

6.).

To

operate

the

receiver

with

the

remote

switch,

the

RECEIVE-STANDBY

switch

on

the

front

panel

must

be

left

at

"STANDBY".

the

hallierafters

co.

MODEL SX-IOO

TRIMMER

TUNING

BAND

SE.LECTOR

"STANDBY

PHONES

ON

CW-SSB @

TM92C5017

Fig.

7.

Operating

Controls

SECTION

3.

FUNCTION

OF

OPERATING

CONTROLS

3-1. SENSITIVITY CONTROL

The

SENSITIVITY

control

varies

the

gain

of

the

RF

amplifier,

1650 kc

IF

amplifier,

and

50.5

kc

IF

amplifier

stages.

Maximum

sensitivity

is

,obtained

with

the

control

set

at

"10"(fully

clockwise}.

In

this

pOSition,

the

tubes

being

controlled

are

operated

at

maximum

gain

with

minimum

cathode

bias.

As

the

control

is

rotated

counterclockwise

the

bias

on

the

tubes

increases

with

a

resultant

decrease

in

gain.

'

3-2.

BAND

SELECTOR

CONTROL

The

BAND

SELECTOR

control

operates

the

band

switch

to

place

the

proper

set

of

coils

and

sections

of

the

main

and

bandspread

tuning

capacitors

into

the

circuit

to

cover

the

desired

frequency

range.

The

frequency

range

covered

by

each

position

of

the

BAND

SELECTOR

control

is

indicated

directly

on

the

control.

3-3. ANTENNA CONTROL

The

ANTENNA TRIMMER

control

operates

a

variable

capaCitor

connected

across

the

secondary

of

the

antenna

coil

of

the

band

in

use.

This

capacitor

adjustment

compensates

for

loading

effects

of

various

types

of

antenna

installations.

The

control

is

normally

adjusted

for

maximum

signal

with

the

MAIN TUNING

control

adjusted

to

the

high

end

of the

band

in

use.

With

most

antenna

systems,

the ANTENNA TRIMMER

control

requires

no

further

adjustment

until

the BAND

SELECTOR

control

is

operated

to

select

another

band.

- 6 -

3-4. VOLUME CONTROL

The

VOLUME

control

adjusts

the

audio

level

at

the

speaker

terminals

and PHONE jack.

Clockwise

rotation

of

the

control

increases

the

signal

applied

to

the

grid

of

the

audio

amplifier

tube,

thus

increasing

receiver

volume;

counter-

clockwise

rotation

decreases

volume.

3-5. AVC SWITCH

The

AVC switch, when

set

at

"ON",

places

the

AVC

circuit

in

operation

to

maintain

the

output

level

of

the

receiver

constant

regardless

of

normal

input-signal

variations.

AVC

voltage

is

applied

to

the

RF

amplifier

stage

and

the

1650

kc

IF

amplifier

stage.

3-6. NOISE LIMITER SWITCH

This

switch,

when

set

at

"ON",

places

the

automatic

series

noise

limiter

circuit

in

operation

to

reduce

pulse

type

noise

such

as

ignition

noise

and

electrical

interference.

The

limiter

circuit

allows

the

signal

to

pass

through

the

receiver

unaffected,

but

makes

the

receiver

inoperative

for

noise

amplitudes

greater

than

those

of

the

signal.

It

will

work

equally

well

on

AM

or

CW

signals

and

is

self-adjusting,

i.

e.,

it

automatically

adjusts

itself

to

the

signal

level.

The

noise

limiter

circuit"

chops"

noise

peaks

received

at

the

detector

by

means

of a

biased

diode which

becomes

non-conducting

above a

predetermined

signal

level.

When

the

limiter

circuit

is

in

operation,

the

audio output

of

the

detector

must

pass

through

the

limiter

diode

to

the

grid

of

the

audio

amplifier.

The

limiter

diode

normally

acts

as

a

conductor

for

the

audio si-gnal

as

long

as

the

diode

plate

is

positive

with

respect

to

its

cathode. When a

noise

peak

is

higher

in

amplitude

than

the

Signal,

it

instantaneously

swings

the

cathode

positive

with

respect

to

the

plate,

conduction

ceases,

and

that

portion

of

the

signal

is

automatically

cut

off

from

the

audio

amplifier.

The

point

at

which

the

limiter

diode

becomes

non-conducting

is

made

sufficiently

high

so

that

the

diode will

not

Clip modulation

peaks

and

thus

impair

intelligibility,

but

yet

low enough

to

limit

the

noise

peaks

effectively.

3-7. AM/CW-SSB SWITCH

This

switch, when

set

at

"CW-SSB",

applies

plate

voltage

to

the

beat

frequency

oscillator

(BFO) to

render

it

opera-

tive

for

the

reception

of

CW

or

single-sideband

signals.

The

beat

frequency

oscillator

employs

a

Hartley

oscillator

circuit

and

is

voltage

regulated

to

insure

high

stable

operation.

The

"AM"position

of

the

AM/CW-SSB

switch

disables

the

BFO

for

normal

reception

of

standard

broadcast

and

AM

phone

signals.

This

switch

also

changes

the

AVC

time

constant

for

CW-SSBreception.

Inthe

CW/SSB pOSition

the

time

constant

is

made

longer,

to

provide

better

AVC

opera-

tion

for

SSB.

KC

OFF

RESONANCE

~

I 6 4 + -

2 0 2 4 8 I •

I

Tr

Ij

I

, I

6

f---

I "

If

I

THE

, Ie'

POSITKIIIS

OIIITTED

I

POR.ClARITY

~

r--

I , •

I ,

,

I

, I

~

,

~I

" I

~\

\

I I I

\~

\

L , I \

, ,

,

m-1

,

I'

, , , ,

,

1\

3KC

I-----:

I-

2Kt

.5'

I,

[\

, , \'

_\

, I I

,

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0

II

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"

1\

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I ,

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I I I , , \

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II

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92E2373

Fig.

8.

IF

Selectivity

Curves

=

C>

~

..

=

- 7 -

20

40

If

-KC

----.{

j4---

NOTCH

FREQUENCI

RANGE

58 54 50

46

42

3

KC

CURVE

r-;

~ITHOUT

NOTCH

~

,

~

'"'

z

..

=

:i'l

80LL--------------------------~--~

92-5015

Fig.

9.

IF

Selectivity

Curve

with Notch

3-8.

SELECTIVITY

CONTROL

The

SELE

CTIVITY

controlis

used

to

vary

the

selectivity

of

the

receiver

to

fit

receiving

conditions.

Five

degrees

of

selectivity

are

available,

ranging

from

500

cycles,

for

CW

reception

under

crowded

band

conditions,

to 5

kilocycles

for

maximum

fidelity

for

broadcast

reception.

The

five

selectivity

positions

are

shown on

the

SELECTIVITY

control

and

indicate

receiver

selectivity

at

6 db

down. A

sixth

position

on

the

control,

marked

"PHONO",

disables

all

the

receiver

circuits

except

the

audio

system

for

phonograph

operation.

The

receiver

IF

selectivity

curves

are

shown

in

Fig.

8.

Note

that

as

the

selectivity

is

varied

from

a

sharp

to

a

broader

position,

the

i-f

passband

not

only

increases

but

also

centers

about

a

higher

frequency.

For

broadcast

reception,

the

SELECTIVITY

control

is

normally

set

at

"5

KC",

the

position

affording

broadest

selectivity.

Se-

lectivity

may

be

progressively

increased

by

turning

the

control

to

the

positions

marked

"3

KC"',

"2

KC",

"I

KC",

and

"5

KC".

For

reception

of

the

crowded

amateur

and

shortwave

bands,

it

is

generally

advisable

to

sacrifice

fidelity

for

greater

selectivity,

since

the

added

selectivity

red.uces both

adjacent-channel

interference

and

background

noise

by

attenuating

the

higher

audio

frequencies.

Too

much

selectivity

on AM

signals,

however,

will

attenuate

the

high

audio

frequencies

to

such

an

extent

that

the

signal

may

be-

come

unintelligible

as

a

result

of

excessive

side-band

cutting.

When

receiving

CW

signals,

the

sharpest

selectivity

pOSition

may

be

used

without

the

loss

of

intelligibility

experienced

in

AM

reception.

3-9. "T" NOTCH

FILTER

The

notch

filter

circuit

provides

a

means

of

eliminating

or

reducing

the

interfering

effect

of

certain

types

of

heterodynes

or

CW

signals.

To

obtain

maximum

results

from

this

feature

of

your

receiver

the

use

of

the

two

controls

associated

with

the

notch

filter

circuit

are

fully

explained

below.

GENERAL

The

manner

in

which

the

notch

filter

will

affect

the

i-f

selectivity

of

the

receiver

is

illustrated

on

page

seven

of

your

instruction

book.

As

shown

in

Fig.

9

the

filter

will

suppress

an

extremely

narrow

band

of

frequencies

within

the

i-f

band

pass

range

of

the

re-

cei

ver.

The

effectiveness

of

this

notch

is

many

times

greater

than

the

notch

of a

quartz

crystal

filter

at

400 kc

t02

mc.

The

NOTCH

FREQUENCY

control

will

move

the

band of

suppressed

frequencies

represented

by

the

notch

in

the

selectivity

curve,

to

any

point

within

the

i-f

passband.

The

NOTCH

DEPTH

control

will

vary

the

depth

of

the

notch

in

the

selectivity

curve

to

control

the

degree

of

rej

ection

of

the

interfering

signal.

Extensive

field

testing

of

this

feature

has

shown

that

the

notch

filter

is

highly

effective

in

suppressing

the

type

of

interference

for

whi'ch

this

type

of

circuit

is

intended.

It

must

be

appreCiated,

however,

that

any

selective

i-f

filter

circuit,

including

the

phasing

notch

of

quartz

crystal

circuits,

affects

only

a

limited

range

of

interfering

frequencies.

The

effectiveness

of

the

notch

filter

is

therefore

somewhat

dependent

upon

the

exact

nature

of

the

interfering

signal.

For

example:

a

heterodyne

within

the

i-f

range

that

is

less

than

900

cycles

in

width

and

has

little

harmonic

content

is

readily

notched

out.

If

the

same

interfering

heterodyne

is

rich

in

harmonics

it

would only be

possible

to

completely

suppress

the

fundamental

frequency

and

the

remaining

harmonic

content

may

re-

main

almost

equally

objectionable.

It

logically

follows

that

if two

interfering

heterodynes

should

appear

within

the

i-f

pass

band

that

are

separated

infrequency

by

more

than

500

to

900

cycles

it

would be

possible

to

notch

out only one

of

the

heterodynes.

The

inter-

fering

Signal

may

also

vary

in

frequency

beyond

the

range

of

the

notch

filter

and

thus

reduce

the

effectiveness

of

the

circuit.

Under

these

conditions,

increasing

selectivity

will

generally

eliminate

its

heterodyne.

If

this

heterodyne

interference

varies

in

frequency

about

some

mean

value

it

may

be

necessary

to

offset

the

notch

depth

control

to

increase

the

broadness

of

the

notch.

It

has

been

found,

however,

that

the

notch

filter

is

sufficiently

effective

in

many

instances

to

make

an

otherwise

useless

signal

entirely

readable.

3-10.

USE

OF

CONTROLS

To

activate

the

Notch

Filter

circuit

advance

the

NOTCH

DEPTH

control

from

the

"OFF"

position.

""

~

",,=

~='->

~~~

oo==

=o.u'"-

~~~

lOA

INCOMING

SIGNAL

NOTE

LSB

-

LOWER

SIDEBAND

USB

-

UPPER

SIDEBAND

""

~

=

~~~

0'),_

"'='"

=o.u=

~g§~

~<3~

lOB

OUTPUT

OF

I

ST

MIXER

!";i

=

'->

'"

~

,

= =

...

o.u

""

~

U">

~

=

!";i

'?

""

'3

10C

2

NO

CONY.

OSC

FREQ

=

1600

KC

""

~

=

...

,

""

U">

~

OUTPUT

OF

2ND

Fig.

10.

Selectable-Sideband

Response

Curves

- 8 -

""

~

=

'"

=

o.u

~

'->

~

'"

,

""

U">

=

100

2ND

CONY

OSC

FREQ

=

1700

KC

MIXER

9202384-1

NOTCH FREQUENCY CONTROL -

This

control

tunes

the

notch

in

the

i-f

pass

band

and

may

be

set

anywhere

in

the

range

of

from

50 kc

to

54

kc.

The

approximate

frequency

is

calibrated

on

the

knob

skirt.

While

tuning

this

control

for

maximum

suppression

of

the

interfering

heterodyne

with

minim~m

distortion

to

the

desired

signal,

try

to

visualize

the

notch

moving

across

the

selectivity

curve,

Fig.

9.

It

is

then

readily

apparent

that

improper

tuning

may

notch

out

the

desired

signal

instead

of

the

heterodyne.

It

may

be

necessary

to

move

the

notch

across

the

desired

signal

in

order

to

reach

the

heterodyne

that

you

desire

to

suppress.

The

im-

portant

consideration

is

to

tune

the

NOTCH FREQUENCY

control

for

maximum

heterodyne

suppression

with

minimum

distortion

to

the

desired

signal.

NOTCH

DEPTH

CONTROL -

As

the

position

of

the

NOTCH FREQUENCY

control

is

changed,

the

depth

of

the

notch

will

vary.

The

NOTCH

DEPTH

control

is

provided

to

retune

the

notch

for

maximum

depth

at

any

setting

of

the

NOTCH FREQUENCY

control

Maximum

notching

occurs

at

the

"0"

setting

when

the

frequency

is

set

to

the

center

of

the

i-f

pass

band.

The

use

of

the

NOTCH

DEPTH

control

is

simply

a

matter

of

tuning

it

for

maximum

suppression

each

time

the

position

of

the

NOTCH FREQUENCY

con-

trol

is

changed.

3-11.

PITCH CONTROL

The

PITCH

CONTROL

operates

the

tuning

slug

in

the

BFO

coil

to

vary

the

frequency

of

beat

frequency

oscillator

approximately

2 kc

each

side

of

its

center

frequency

of

50

kc.

The

primary

function

of

the

PITCH

CONTROL

is

to

vary

the

pitch

of

the

audible

beat

note

when

receiving

CW

signals.

It

is

also

used

when

receiving

Single-sideband

signals

to

vary

the

frequency

of

the

reinserted

carrier

in

the

receiver.

3-12.

RESPONSE

CONTROL

The

RESPONSE

control

performs

three

functions:

(1)

it

turns

the

receiver

on

and

off,

(2)

it

switches

the

2nd

conversion

oscil-

lator

to

operate

atthe

required

frequency

for

reception

of CW, AM,

and

single-sideband

signals

(1600 kc

in

the

"LOWER

SIDEBAND"

position

and

1700 kc

in

the

"UPPER

SIDEBAND",

"TREBLE

CUT",

and

"NORMAL"

positions),

and

(3)

it

serves

as

a

two-position

tone

control

for

AM

reception

and

phono

operation.

In

the

"POWER

OFF"

position,

the

recei

ver

is

inoperative.

As

the

control

is

turned

clockwise

to

any of

the

other

four

positions,

the

receiver

is

turned

on.

The

"LOWER SIDEBAND"

and

"UPPER

SIDEBAND"

positions

of

the

control

are

us'ed

when

receiving

single-sideband

signals

or

when

it

is

deSired

to

receive

only

one

sideband

of

an

AM

signal.

The

"TREBLE

CUT"

and

"NORMAL" pOSitions

are

used

for

phono

operation

and

for

normal

AM

reception

where

both

sidebands

are

received.

In

the

"NORMAL"

position,

the

audio

response

is

essentially

flat

at

the

low-

and

mid-frequencies

and

slightly

at-

tenuated

at

the

high

frequencies.

The

response

in

the

"TREBLE

CUT"

position

is

essentially

the

same

except

that

the

high

fre-

quencies

are

attenuated

considerably

more

than

in

the

"NORMAL"

position.

For

CW

reception,

the

setting

of

the

RESPONSE

control

is

immaterial

although

a

slight

improvement

in

signal-to-noise

ratio

will

be

obtained

in

the

"LOWER

SIDEBAND"

and

"UPPER

SIDEBAND"

positions.

To

illustrate

how

selectable

sideband

reception

is

accomplished

in

the

receiver,

a

numerical

example

is

given.

Consider

an

incoming

signal

at

7000

kc,

modulated

1

kc.

Since

modulation

of a

carrier

causes

the

generation

of

sideband

frequencies

numeri-

cally

equal

to

the

carrier

frequency

plus

or

minus

the

modulation

frequency,

the

incoming

signal

consists

of

the

carrier

at

7000

kc,

a

lower

sideband

at

6999

kc,

and

an

upper

sideband

at

7001

kc.

(See

Fig.

lOA.)

The

incoming

Signal

is

first

heterodyned

with

the

output of

the

1st

conversion

oscillator

in

the

1st

mixer

stage.

The

1st

con-

version

oscillator

operates

at

a

frequency

higher

than

the

incoming

signal

by

an

amount

equal

to

the

first-intermediate

frequency

of 1650

kc.

As

a

result

of

the

frequency

conversion

process,

three

new

lower

frequencies

are

produced

in

the

output of

the

1st

mixer:

the

carrier

at

1650

kc,

the

lower

sideband

at

1651

kc,

and

the

upper

sideband

at

1649

kc.

(See

Fig.

lOB.)

These

Signals

are

amplified

by

the

1650kc

IF

amplifier

stage

and

then

heterodyned

with

the

output of

the

2nd

conversion

oscillator

in

the

2nd

mixer

stage.

The

2nd

conversion

oscillator

is

crystal

controlled

and

can

be

set

to

operate

at

either

1600 kc

for

reception

of

the

lower

Sideband

or

1700 kc

for

the

reception

of

the

upper

sideband,

selection

being

made

by

means

of

the

RESPONSE

control.

When

the

RESPONSE

control

is

set

at

"LOWER

SIDEBAND",

the

1600 kc

signal

from

the

2nd

conversion

oscillator

is

heterodyned

with

the

incoming

signal

at

the

first-intermediate

frequency

of 1650 kc

to

produce

three

new

frequencies:

the

carrier

at

50

kc,

the

lower

sideband

at

51

kc,

and

the

upper

sideband

at

49

kc.

By

referring

to

Fig.

10C,

it

can

be

seen

that

the

lower

sideband

falls

within

the

i-f

passband

and

the

upper

sideband

falls

outside

of

the

passband.

Thus

the

lower

sideband

is

accepted

and

the

upper

sideband

is

re-

jected.

When

the

RESPONSE

control

is

set

at

"UPPER

SIDEBAND",

the

1700 kc

Signal

from

the

2nd

conversion

oscillator

is

heter-

odyned

with

the

incoming

signal.

In

the

frequency

conversion

process,

the

carrier

still

remains

at

50

kc,

but

now

the

upper

side-

band

appears

at

51

kc,

and

the

lower

sideband

appears

at

49

kc.

(See

Fig.

10D.)

Thus,

the

upper

sideband

IS

accepted

and

the

lower

sideband

is

rejected.

3-13. CALIB. ON-OFF

SWITCH

The

CALIB.

ON

-OFF

switch

controls

the

operation

of

the

built-in

crystal

calibrator.

When

the

switch

is

set

at

"ON",

the

crystal

calibrator

is

turned

on

to

provide

marker

signals

at

every

100 kc on

the

dial.

The

crystal

calibrator

employs

a

crystal

controlled,

pentode

oscillator

circuit.

The

output

of

the

crystal

calibrator

is

capacitively

coupled

to

the

antenna

input

circuit.

A

trimmer

ca-

pacitor,

adjustable

by

the

CRYSTAL ADJ

control

on

the

top

of

the

calibrator

unit,

permits

adjustment

of

the

calibrating

crystal

to

exactly

100 kc by

comparison

with

the

frequencies

transmitted

by WWV.

This

capacitor

has

been

set

at

the

factory

and

should

nor-

mally

not

require

periodic

readjustment

unless

extreme

calibration

accuracy

is

required.

If

adjustment

is

required,

proceed

as

outlined

in

Section

4-8.

3-14. RECEIVE-STANDBY

SWITCH

The

RECEIVE-STANDBY

switch,

normally

set

at

"RECEIVE",

permits

disabling

of

the

receiver

during

transmission

periods,

atthe

same

time

maintaining

the

heater

and

plate

supplies

operative

for

instant

use

when

reception

is

again

resumed.

The

receiver

is

disabled

by

setting

the

RECEIVE-STANDBY

switch

at

"STANDBY".

One

section

ofthe

RECEIVE

-STANDBY

switch

is

available

for

relay or

transmitter

switching.

For

connections

and

details,

re-

fer

to

Section

2-8.

- 9 -

3-15. TUNING and BANDSPREAD CONTROLS

The

TUNING and BANDSPREAD

controls

are

used

in

conjunction

with

one

another

to

tune

in

the

desired

signal.

Wide

tuning

is

performed

with

the

TUNING

control

and

fine

tuning

with

the

BANDSPREAD

control.

Main Tuning

Dial.

The

main

tuning

or

left-hand

dial

is

operated

by

the

TUNING

control.

This

dial

has

four

calibrated

scales,

one

for

each

of

the

four

frequency

bands

covered

by

the

receiver.

It

also

contains

a

hundredths

scale,

used

with

the

unit

scale

on

the

MAIN TUNING knob,

for

accurately

logging

and

relocating

stations

of

special

interest.

The

logging

number

is

the

logging

number

on

the

dial

plus

the

number

on

the

knob

scale.

For

example;

if

the

main

tuning

dial

logging

scale

reads

12,

and

the

MAIN TUNING

control

knob

scale

reads

25,

the

logging

number

is

1225.

For

normal

tuning,

the

main

tuning

dial

is

set

for

the

desired

station

frequency

after

the

BAND-

SPREAD

control

has

been

set

fully

counterclockwise

(bandspread

tuning

capacitor

set

at

minimum

capacity)

.

IMPORTANT:

The

readings

on

the

main

tuning

dial

will

correspond

to

the

station

frequencies

only

if

the

BANDSPREAD

control

is

set

fully

counterclockwise.

If

it

is

set

at

any

other

setting,

the

additional

bandspread

capacity

added

to

the

main

tuning

capacity

will

throw

off

the

main

tuning

dial·

calibration

because

the

receiver

has

been

calibrated

with,

the

bandspread

tuning

capaCitor

set

at

minimum

capacity.

The

dial

settings

for

the

80, 40, 20, 15,

and

11-10

meter

amateur

bands

are

indicated

on

the

main

tuning

dial

by

white

dots.

When

tuning

the

amateur

bands

with

the

bandspread

dial,

the

main

tuning

dial

must

be

set

at

the

dot

corresponding

to

the

desired

amateur

band.

The~,

meter

amateur

band

is

indicated

on

the

dial

by

three

short

double-weight

lines.

NOTE

The

broadcast

band

is

marked

with

a

"CD"

emblem

and

a

dot

at

.64

and 1.24

megacycles

to

indicate

the

two

official

civil

defense

frequencies,

In

a

civil

defense

emergency,

tune

to

either

of

these

two

frequen-

cies

for

official

defense

news,

instructions,

and

information.

Bandspread Dial.

The

bandspread

or

right-hand

dial

is

operated

by

the

BANDSPREAD

control.

This

dial

contains

five

scales

calibrated

for

the

80, 40, 20, 15,

and

11-10

meter

amateur

bands.

These

five

scales

are

calibrated

to

read

receiver

frequency

directly

when

the

main

tuning

dial

has

been

set

to

the

index

dot

of

the

desired

amateur

band.

It

also

contains

a

hundredths

scale

for

logging

purposes.

The

logging

procedure

for

the

band-

spread

dial

is

the

same

as

for

the

main

tuning

dial.

For

convenience

in

tuning,

the

AM

phone

bands

are

indicated

on

the

bandspread

dial

by

double-weight

lines.

In

addition

to

its

use

on

the

amateur

bands,

the

bandspread

dial

may

also

be

utilized

as

a fine

tuning

adjust-

ment

over

any

portion

of

the

receiver

tuning

range.

Two

methods

of

fine

tuning

are

described

below.

a.

The

first

method

of

fine

tuning

is

used

when

it

is

desired

to

tune

in

a

single signal

with

precision

accuracy.

First

the

BANDSPREAD

control

is

set

a few

degrees

from

its

full

counterclockwise

pOSition,

then

the

desired

signal

is

located

with

the

TUNING

control,

and

finally

the

signal

is

accurately

tuned

in

by

"rocking"

the

BANDSPREAD

control

(turning

it

slightly

to

the

left

and

right)

until

the

signal

is

loudest

and

clearest.

b.

The

second

method

of

fine

tuning

is

used

when

it

is

desired

to

tune

through

a

range

of

frequencies,

such

as

a

group

of

shortwave

stations.

Set

the

BANDSPREAD

control

fully

counterclockwise,

set

the

TUNING

control

for

the

high

end

of

the

selected

range

of

frequencies,

and

then

tune

through

the

range

with

the

BANDSPREAD

control.

Turning

the

BANDSPREAD

control

clockwise

tunes

the

receiver

progressively

lower

in

frequency.

4-1.

AM

RECEPTION

SECTION

4·

OPERATION

1.

Set

the

front

panel

controls

to

their

starting

positions

as

outlined

below.

SENSITIVITY

..............

, 10

(maximum

sensitivity)

SELECTIVITy

..............

5

KC

BAND

SELECTOR

..........

At

the

desired

band.

RESPONSE

.................

POWER

OFF

VOLUME

..................

°

(minimum

volume)

RECEIVE-STANDBy

........

RECEIVE

AVC

ON-OFF

..............

ON NOTCH

DEPTH

.............

OFF

NOISE

LIMITER

OFF-ON

....

OFF

CALIB.

ON-OFF

...........

OFF

AM/CW-SSB

...............

AM

2.

Turn

the

receiver

on

by

rotating

the

RESPONSE

control

clockwise

and

set

it

at

either

the

"NORMAL"

or

"TREBLE

CUT"

position.

The

tuning

dials

will

light

up

indicating

the

receiver

is

operative.

Rotate

the

VOLUME

control

clockwise

for

the

desired

volume

level.

3.

Set

the

bandspread

tuning

gang

at

minimum

capacity

by

rotating

the

BANDSPREAD'control

fully

counterclock-

wise.

To

utilize

the

BANDSPREAD

control

as

a fine

tuning

adjustment

for

the

amateur

and

shortwave

bands,

refer

to

Section

3-15.

-10 -

IMPORTANT

The

calibration

on

the

main

tuning

(left-hand)

dial

will

be

correct

only

if

the

bandspread

tuning

gang

is

set

at

minimum

capacity.

If

it

is

set

at

any

other

setting,

the

additional

bandspread

capacity

added

to

the

main

tuning

capacity

will

throw

off

the

main

tuning

dial

calibration

because

the

receiver

has

been

calibrated

with

band-

spread

tuning

gang

set

at

minimum

capacity.

4.

Tune

in

the

desired

signal

with

the

TUNING

control,

tuning

for

maximum

indication

on

the

"S"

meter.

After

the

Signal

has

been

accurately

tuned

in,

readjust

the

VOLUME

control

as

desired.

NOTE:

The

"S"

meter

indications

will

be

correct

only

when

the

AVC

switch

is

set

at

"ON",

and

the

SENSI-

TIVITY

control

is

set

at

"10"

(maximum

sensitivity).

Setting

the

SENSITIVITY

control

at

a

setting

other

than

"10"

will

also

somewhat

restrict

AVC

action.

5.

Set

the

SELECTIVITY

control

for

the'

desired

degree

of

selectivity.

For

standard

broadcast

reception

(Band 1),

the

control

is

normally

set

to

"5

KC"

for

maximum

fidelity.

The

positions

marked

"3

KC",

"2

KC",

"1

KC",

".5

KC"

provide

progressively

increasing

steps

of

selectivity.

Note

that

as

the

selectivity

of

the

receiver

is

increased,

the

background

noise

and

interference

from

adjacent

signals

is

reduced.

Too

much

selectivity,

however,

may

cause

excessive

side-band

cutting.

While

side-band

cutting

reduces

fidelity,

it

may

be

frequently

preferable

to

sacrifice

naturalness

of

reproduction

in

favor

of

communications

effectiveness.

When

changing

the

pOSition of

the

SELECTlVITY

control

from

a

broad

to

a

narrower

response

(for

example:

from

"2

KC"

to

"1

KCf'), a

slight

readjustment

of

the

tuning

controls

may

be

necessary

to

recenter

the

signal

in

the

i-f

passband.

6.

Set

the

RESPONSE

control

at

either

"NORMAL"

or

"TREBLE

CUT"

for

thE:

desired

tonal

quality.

7.

If

it

is

desired

to

operate

with

AVC off,

set

the

AVC

switch

at

"OFF",

set

the

VOLUME

control

to

a

well

ad-

vanced

position,

and

vary

the

receiver

volume

level

by

means

of

the

SENSITIVITY

control,

taking

care

not

to

advance

the

control

to

a

point

where

strong

signals

will

cause

"blocking".

8.

If

severe

electrical

disturbances

or

ignition

or

other

types

of

pulse

type

noise

interfere

with

reception,

set

the

NOISE

LIMITER

switch

at

"ON"

to

place

the

automatic

noise

limiter

circuit

in

operationo

9.

The

receiver

may

be

disabled

without

turning

it

off

by

setting

the

RECEIVE-STANDBY

switch

at

"STANDBY".

In

this

pOSition,

the

r-f

and

50.5

kc

i-f

stages

are

cut

off

but

the

heater

and

plate

supplies

remain

operative

for

instant

reception.

To

resume

reception,

simply

return

the

switch

to

the

"RECEIVE"

position.

10.

An

undesired

Signal

close

in

frequency

to

a

desired

signal

will

heterodyne

with

it

to

produce

an

audible

beat

note

equal

to

their

frequency

difference.

This

type

of

heterodyne

interference

can

be

eliminated

by

utilizing

the

selectable

sideband

feature

of

the

receiver

to

position

the

undesired

signal

out

of

the

i-f

passband.

The

detailed

procedure

for

eliminating

heterodyne

interference

is

as

follows:

a.

Set

the

AMjCW-SSB

switch

at

"CW-SSB",

the

PITCH

CONTROL

to

"0",

and

the

RESPONSE

control

at

either

"LOWER

SIDEBAND"

or

"UPPER

SIDEBAND".

b.

Carefully

tune

in

the

desired

Signal

for

"zero

beat".

Then

set

the

AMjCW

-SSB

switch

at

"AM".

c.

If

the

RESPONSE

control

has

been

set

to

the

proper

sideband

position,

the

heterodyne

interference

will

be

eliminated.

If

the

interference

is

still

present,

simply

switch

the

RESPONSE

control

to

the

opposite

sideband

position.

11.

An

alternate

method

of

eliminating

an

interfering

signal

is

to

use

the

notch

filter

circuit.

Simply

rotate

the

NOTCH

DEPTH

control

clockwise

to

"0"

and

adjust

the

NOTCH

FREQ

control

to

"notch

out"

the

interfering

signal.

Readjust

the

NOTCH

DEPTH

control

as

necessary

to

obtain

maximum

rejection

of

the

interfering

signal.

CAUTION

It

is

possible

to

eliminate

the

heterodyne

by

notching

out

the

desired

carrier

in

place

of

the

undesired

signal

or

carrier.

When

this

occurs

an

AM

signal

will

sound

like

a

single

sideband

suppressed

car-

rier

transmission.

12.

In

shortwave

reception,

it

frequently

happens

that

transmission

conditions

are

different

for

waves

of

slightly

different

frequencies.

As

a

result,

in

the

case

of

voice-modulated

transmissions,

which

involve

sideband

frequencies

differing

slightly

from

the

carrier

frequency,

the

carrier

and

sideband

components

may

not

be

received

in

the

same

relative

amplitude

and

phases

they

had

at

the

transmitter.

This

effect,

known

as

selective

fading,

causes

severe

distortion

of

the

signal.

This

type

of

distortion

can

be

reduced

somewhat

by

tuning

the

receiver

to

accept

only

one

of

the

two

sidebands

being

transmitted

as

outlined

in

Steps

10(a)

and

(b)

above.

After

tuning

is

completed,

switch

the

RESPONSE

control

from

"LOWER

SIDEBAND"

to

"UPPER

SIDEBAND"

and

leave

it

in

the

pOSition

providing

the

least

distortion.

4-2.

CW

RECEPTION

For

CW

reception,

the

receiver

may

be

operated

with

AVC

onor

off,

as

desired.

Operation

of

the

receiver

with

AVC

on

is

highly

deSirable

since

it

not

only

minimizes

fading

but

also

prevents

blasting

when

tuning

from

a

weak

to

a

-11 -

strong

signal.

To

operate

with

AVC on,

set

the

AVC

switch

at

"ON",

set

the

SENSITIVITY

control

to

a

well

advanced

position,

and

regulate

the

receiver

volume

level

by

means

of

the

VOLUME

control.

To

operate

with

A

VC

off,

set

the

AVC

switch

at

"OFF",

set

the

volume

control

at

a

well

advanced

position,

and

vary

the

receiver

volume

level

by

means·

of

the

SENSITIVITY

control,

taking

care

not

to

advance

the

control

to

a

point

where

strong

signals

cause

excessive

"thumping"

(overloading).

CW

signals

are

made

audible

by

the

heterodyning

action

of

the

beat

oscillator

with

the

incoming

signal.

The

beat

oscillator

is

set

at

a

frequency

slightly

different

from

the

second-intermediate

frequency.of

50.5

kc,

the

difference

being

equal

to

the

pitch

of

the

audible

note

desired.

For

the

reception

of

CW

signals,

set

the

AM/CW-SSB

switch

at

"CW-SSB",

set

the

SELECTIVITY

control

at

".5

KC" (the

sharpest

selectivity

position),

set

the

RESPONSE

control

at

"UPPER

SIDEBAND", and

set

the

PITCH

CONTROL

at

any

setting

from

"2"

to

"4"

on

either

side

of

zero,

and

then

tune

in

the

signal

for

a

pleasing

beat

note.

The

beat

oscillator

may

be

set

on

either

the

high-

or

low-frequency

side

of

zero

beat.

(The

oscillator

operates

on

the

low

side

when

the

PITCH

CONTROL

is

set

at

a

position

to

the

left

of

zero

and on

the

high

side

when

the

PITCH

CON-

TROL

is

set

at

a

position

to

the

right

of

zero.)

It

may

be

necessary,

after

setting

the

PITCH CONTROL,

to

readjust

the

receiver

tuning

slightly

to

properly

position

the

signal

in

the

i-f

passband.

Alternately

adjust

the

PITCH CONTROL

and

the

receiver

tuning

for

a

maximum

audible

signal.

With

the

receiver

in

the

sharpest

selectivity

position,

CW

signals

will

drop

in

and

out

rapidly

and a

slow

rate

of

tuning

is

recommended.

Once

the

PITCH CONTROL

has

been

set,

it

need

not

be

reset

for

each

CW

signal.

NOTE

If

a

CW

Signal

is

tuned

in

with

the

SELECTIVITY

control

at

a

setting

other

than

".5

KC",

it

may

be

necessary

to

slightly

readjust

the

receiver

tuning

when

changing

to

a

narrower

selectivity

position

in

order

to

properly

position

the

signal

in

the

i-f

passband.

The

setting

of

the

SELECTIVITY

control

for

CW

reception

is

generally

best

determined

by

receiving

conditions.

Note

that

as

the

selectivity

of

the

receiver

is

increased

(SELECTIVITY

control

varied

from

the

"5

KC"

to

the

".5

KC"

position),

the

background

noise

and

adjacent-channel

interference

is

considerably

reduced.

For

CW

reception,

the

sharpest

selectivity

position

may

be

used

without

the

loss

of

intelligibility

experienced

in

AM

reception.

The

automatic

noise

limiter

circuit

can

be

used

to

great

advantage

on

CW

reception,

just

as

on AM

reception,

to

reduce

the

effects

of

background

noise

and

electrical

interference.

To

place

the

noise

limiter

circuit

in

operation,

set

the

NOISE LIMITER

switch

at

"ON".

The

notch

filter

may

be

used

to

eliminate

or

attenuate

an

interfering

signal

during

CW

reception.

4-3.

SINGLE

SIDEBAND

RECEPTION

Single-Sideband

signals

are

transmitted

with

little

or

no

carrier,

and

it

is

necessary

to

reinsert

the

carrier

in

the

receiver

before

proper

reception

is

obtained.

In

the SX-IOO

receiver,

this

is

accomplished

in

the

50.5

kc

i-f

system

by

injecting

the

beat

oscillator

Signal

at

the

input of

the

second-detector.

A

Single-sideband

signal

can

be

identified

by

its

unintelligibUty

and

by

a

severe

variation

in

the

"S"

meter

indication

corresponding

to

the

speech

modulation.

For

the

reception

of

Single-sideband

signals,

set

the

PITCH

control

at

"0",

AVC

switch

at

"ON", AM/CW

-SSB

switch

at

"CW-SSB", and SELECTIVITY

control

at

either

"1

KC"

or

"2 KC", depending upon

adjacent

channel

inter-

ference

and

noise.

Set

the

SENSITIVITY

control

at

a

well

advanced

position

and

vary

the

receiver

volume

level

by

means

of

the

VOLUME

control,

taking

care

not

to

advance

the

SENSITIVITY

control

to

a

point

where

strong

signals

will

cause

distortion

(overloading).

Set

the

RESPONSE

control

at

either

"LOWER SIDEBAND"

or

"UPPER

SIDEBAND".

The

single-sideband

signal

will

be

intelligible

in

only one of

these

two

positions,

the

proper

position

depending upon

the

Sideband

being

transmitted.

If

the

signal

is

not

intelligible

after

tuning

is

completed

as

outlined below,

set

the

RESPONSE

control

to

the

other

sideband

setting

and

repeat

the

tuning

procedure.

It

is

suggested

that

the

RESPONSE

control

be

initially

set

at

"LOWER

SIDEBAND"

since

most

single-sideband

transmissions

are

of

this

type.

After

the

controls

have

been

properly

set

as

outlined

in

the

preceding

paragraph,

very

carefully

tune

in

the

single-sideband

signal

for

maximum

intelligibility.

It

will

be

noticed

that

with

incorrect

tuning

of

a

single-sideband

signal,

the

speech

will

sound

high-

or

low-pitched

or

very

distorted

but no

trouble

should

be

had

in

tuning

once

a

little

experience

has

been

gained.

The

"1

KC"

pOSition of

the

SELECTIVITY

control

permits

reception

of

modulation

frequencies

up

to

about

1000

cycles.

For

reception

of

modulating

frequencies

higher

than

1000

cycles,

set

the

SELECTIVITY

control

to

the

positions

marked

"2

KC",

"3

KC" and

"5

KC", depending

on

the

degree

of

fidelity

desired;

maximum

fidelity

is

obtained

in

the

"5

KC"position.

It

is

not

necessary

to

retune

the

receiver

when

receiver

selectivity

is

varied.

The

notch

filter

is

es-

pecially

useful

during

reception

of

single-sideband

signals.

An

undesired

AM

or

CW

signal

close

in

frequency

to

the

de-

sired

signal

will

heterodyne

with the

beat

oscillator

to

produce

an

audible

beat.

The

undesired

signal

may

be

"notched

out"

with the notch

filter,

just

as

in

AM

or

CW

reception.

4-4.

USE

OF

CRYSTAL

CALIBRATOR

The

built-in

100 kc

crystal

calibrator

permits

accurate

checking

of

dial

calibration

over

any

portion

of

the

main

and

bandspread

tuning

dials

by a

comparison

of

the

dial

calibrations

with the

marker

signals

which

appear

at every

multiple

of

100 kc on

the

dial.

A. CALIBRATION

OF

THE BANDSPREAD DIAL

1.

Set

the

bandspread

tuning

dial

at

a

convenient

multiple

of

100 kc

at

the

high

frequency

end of

the

band

in

use.

For

-

12

-

example:

2000kcon160M,

4000kcon80M,

7300 kc on 40M,

14,400

kc on 20M,

21,500

kc on 15M, and

29,800

kc

on 10M. (The

bandspread

tuning

dial

is

calibrated

in

kc.)

2.

Set

the

main

tuning

dial

to

the

index dot

of

the

desired

amateur

band.

3.

Set

the AM/CW-SSB

switch

at

"CW",

the

PITCH

control

at

"0",

and

the

CALIB.

ON-OFF

switch

at

"ON".

4.

Very

carefully

adjust

the

main

tuning

control

for

exact

frequency

as

indicated

by

"zero

beat".

The

bandspread

tuning

dial

is

now

accurately

calibrated

and a

"zero

beat"

should be obtained

at

every

multiple

of 100 kc on

the

band

in

use.

For

example,

on the 80

meter

amateur

band, a

"zero

beat"

should

be

obtained

at

or

close

to

3500,

3600, 3700, 3800, 3900, and 4000

kc.

5.

The

procedure

outlined

in

steps

1

through

4 above

provides

average

.calibration

accuracy

over

the

entire

frequency

range

of

the

band

in

use.

For

precise

calibration

accuracy

over

a

particular

section

of

the

band,

the

procedure

is

identical

except

that

the

bandspread

dial

is

set

at

a

multiple

of 100 kc

near

the

desired

frequency

or

range

of

fre-

quencies,

instead

of

at

the high end of

the

band

as

in

Step

1.

B.

CALIBRATION OF THE MAIN TUNING DIAL

1.

Turn

the

BANDSPREAD tuning

control

counterclockwise

until

the

dial

pOinter

is

aligned

with

the

index

marks

at

the

high

frequency

end of

the

dial.

2.

Set

the

main

tuningdial

at

a convenient

multiple

of

100 kc

near

the

desired

frequency

or

range

of

frequencies.

(The

main

tuning

dial

is

calibrated

in

mc.)

To

determine

the

nearest

100 kc

multiple,

simply

remember

that

100 kc

is

equaltoone-tenth

mc.

For

example,

from

2.0

to

3.0

mc

on

band

2,

the

100 kc

multiples

are

2.0

mc,

2.1

mc,

2.2

mc,

2.3

mc,

etc.

3.

Set

the

AM/CW-SSB

switch

at

"CW",

and the PITCH

control

to

"0".

Then

set

the

CALIB.

ON-OFF

switch

at

"ON"

and

very

carefully

adjust

the

main

TUNING

control

for

a

"zero

beat".

The

main

dial

pointer

should

index

with a 100 kc

multiple

on

the

dial.

4.

If

calibration

is

required,

refer

to

steps

5

through

8 of

the

alignment

procedure,

Section

5-3.

4-5.

USE

OF

"5"

METER

The

"s"

meter

provides

a

visual

means

of

determining

whether

or

not

the

receiver

is

properly

tuned,

as

well

as

an

indication

of

the

relative

signal

strength.

The

"s"

meter

circuit

consists

of a

DC

milliammeter

connected

in

series

with

the

plate

lead

to

the

1650 kc

IF

amplifier

tube

(V

-4),

the

grid

of

which

is

controlled

by AVC

voltage.

Since

the

plate

current

of

this

tube

varies

with

the

strength

of

the

incoming

signal,

the

meter

will

indicate

relative

signal

strength.

The

"s"

meter

is

calibrated

in

microvolts,

"S"

units

from

1

to

9,

and

in

decibels

above

S-9

to

+ 80 db.

The

indications

on

the

"s"

meter

will

be

correct

only

when

the

SENSITIVITY

control

is

set

at

"10"

(maximum

sensitivity),

and

the

A

VC

switch

is

set

at

"ON".

The

limitations

of

the

microvolt

scale

should

be fully

appreciated

before

any

assumption

as

to

the

indicated

signal

voltages

is

accepted.

The

meter

indicates

approximate

microvolts

of

signal

strength

as

developed

at

the

antenna

input

terminals

when

terminated

in

a

300-ohm

load,

at

5. 1

mc.

This

approximation

will have a

variation

of ± 5 db on a new

receiver

and, obviously,

as

the

tubes

age

the

variations

may

be

greater.

The

indicated

microvolt

readings

at

30, 7,

and

3.5

mc

will

vary

approximately

± 3 db

from

that

at

5.1

mc.

Also,

all

readings

50

microvolts

or

less

will

be

more

accurate

and

correlate

more

closely

than

those

higher.

Variations

in

the

microvolt

indications

between

receivers

is

not

indicative

of

the

overall

sensitivity

but

is

caused

by

normal

tolerances

in

vacuum

tube

conductances

which

are

reflected

as

variations

in

the

A

VC/"S"

Meter

curve.

Thus,

two

receivers

with

identical

sensitivities

could,

under

the

same

signal

conditions

indicate

signal

levels

of 5

microvolts

and 25

microvolts

and

yet

each

be

a

perfect

receiver.

4-6.

BFO

FREQUENCY

CHECK

The

beat

frequency

oscillator

(BFO)

has

been

carefully

adjusted

at

the

factory

so

that

its

frequency

is

50 kc

when

the

PITCH CONTROL knob

is

set

at

"0".

Readjustment

of

the

BFO

will

normally

not

be

required

unless

the

6SC7

BFO tube (V

-8)

or

components

in

the

BFO

circuit

have

been

replaced.

A

slight

readjustment

may

sometimes

be

nec-

essary

as

a

result

of

normal

aging

of

the

BFO

tube.

A

simple

check

can

be

made

to

determine

if

adjustment

is

neces-

sary

as

follows:

With

the

AM/CW-SSB

switch

at

"CW-SSB", SELECTIVITY

control

at

"5

KC", RESPONSE

control

at

"UPPER

SIDEBAND", and PITCH CONTROL

at

"0"

,very

carefully

tune

in

an

AM

signal

for

"zero

beat".

.(See Note

Abelow.)

Leaving

the

receiver

tuning unchanged,

switch

the

RESPONSE

control

to

the

"LOWER SIDEBAND"

posltion.

If

the

beat

oscillator

frequency

is

correct,

a

"zero

beat"

will

be

obtained

in

both

the

"UPPER

SIDEBAND" and

"LOWER

SIDEBAND"

positions.

If,

however,

the

beat

oscillator

is

slightly

off

frequency,

a

beat

note

will

be

heard

when

switching

from

the

"UPPER

SIDEBAND"

to

the

"LOWER SIDEBAND" pOSition.

Adjustment

of

the

beat

frequency

oscillator

is

necessary

only

if

the

frequency

of

the

audi'ble

beat

note

exceeds

200

cycles.

~

Note A -

In

instances

where

the

beat

oscillator

is

considerably

off

freauency,

it

may

not be

possible

to

obtain

a

"zero

beat"

when tuning

in

the

signal.

In

this

case,

it

will

be

necessary

to

first

"roughly"

set

the

beat

oscillator

to

operate

at

approximately

50 kc

as

follows:

With

the AM/CW-SSB

switch

at

"CW-SSB", SELECTIVITY

control

at

-

13

-

".5

KC", and RESPONSE

control

at

"UPPER

SIDEBAND",

tune

the

receiver

to

a

noisy

part

of

the

band (not

to

a

signal).

Remove

the

PITCH

CONTROL knob

and

adjust

the

BFO

slug

foy mi.nimum

noise

on

the

noise

signal.

Then

set

the

SELECTIVITY

control

at

"5

KC"

and

m'lke

the

BFO

frequency

check

as

outlined

in

the

preceding

paragraph.

If

the

BFO

frequency

check

indicates

adjustment

is

necessary,

proceed

as

follows:

Remove

the

PITCH

CONTROL knob

and

turn

the

BFO

slug

a few

degrees

to

the

left

or

right

so

as

to

lower

the

beat

note

frequency,

and

repeat

the

BFO

frequency

check.

If

the

beat

note

obtained

is

higher

in

frequency

than

that

obtained

originally,

it

is

an

indication

that

the

slug

is

being

turned

in

the

wrong

direction.

Continue

varying

the

setting

of

the

slug

in

small

steps

and

repeating

the

BFO

frequency

check

until

"zero

beat"

is

obtained

in

both

the

"UPPER

SIDEBAND" and

"LOWER

SIDEBAND"

positions.

After

the

correct

slug

setting

is

determined,

replace

the

PITCH

CONTROL knob

with

"0"

in

the

top

center

pOSition,

being

careful

not

to

disturb

the

slug

setting.

4-7.

NOTCH

FREQUENCY CHECK

Readjustment

of

the

notch

filter

circuit

is

not

normally

necessary

unless

the

components

in

the

notch

filter

,circuit

are

replaced.

To

check

the

circuit,

proceed

as

follows:

Checkthe

BFOfrequency

as

instructed

in

Section

4-6.

Set

the

PITCH

CONTROL

at

"0",

AVC

to

"ON"

and

the

SE-

LECTIVITY

control

at

"3

kc".

Tune

in

an

unmodulated

carrier,

from

a

station

or

a

signal

generator,

for

a

"zero

beat" .

Place

the

AMI

CW

-SSB

switch

in

the

AM

position

to

de

-energize

the

BFO.

Rotate

the

NOTCH

DEPTH

control

to

"0".

Tune

the

NOTCH

FREQforaminimum

reading

on

the

"S"

meter.

The

NOTCH

FREQ

dial

should

be

set

at

"50"

kc.

If

the

notch

frequency

check

indicates

that

an

adjustment

is

necessary,

proceed

as

follows:

Loosen

the

NOTCH

FREQ

knob

and

reset

it

to

indicate

"50"

kc.

Rotate

the

control

to

approximately

"51"

kc.

Tune

across

an

unmodulated

carrier

while

observing

the

"S"

meter.

(Use

an

approximate

S-9

signal.)

The

meter

will

in-

dicate

two

peaks.

Readjust

the

NOTCH

FREQ

control

as

necessary

to

approximately

equalize

the

peaks.

Then

tune

the

receiver

for

a

minimum

reading

on

the

"S"

meter

between

the

two

peaks.

Adjust

R75,

located

on

the

side

of

the

notch

filter

chaSSiS,

for

a

minimum

reading

on

the

"S"

meter.

Refer

to

Fig.

11

for

the

location

of

R75.

4-8.

CRYSTAL CALIBRATOR CHECK

The

CRYSTAL ADJ

control

on

the

calibrator

chassis

operates

a

trimmer

capacitor

connected

across

the

100 kc

cali-

brating

crystal.

This

trimmer

capacitor

permits

adjustment

of

the

calibrating

crystal

to

exactly

100 kc by

comparison

with

the

frequencies

transmitted

by

station

WWV.

This

capacitor

has

been

set

at

the

factory

and

should

not

require

peri-

odic

readjustment

unless

extreme

calibration

accuracy

is

desired.

If

adjustment

is

required,

proceed

as

outlined

below.

Set

the

RESPONSE

switch

to

"NOR",

the

CALIB.

ON-OFF

switch

at

"OFF",

and

all

other

front

panel

controls

as

for

normal

AM

reception.

Tune

in

station

WWV

on

anyone

of

its

operating

frequencies

(2.5,

5, 10, 20,

or

25

mc)

and

wait

for

the

period

during

which

the

signal

from

WWV

is

unmodulated.

Then

switch

on

the

crystal

calibrator

by

setting

theCALIB.

ON-OFF

switch

at

"ON"

and

adjust

its

frequency,

by

means

of

the

CRYSTAL

ADJ

control,

until

the

crystal

calibrator

signal'

'zero

beats"

with

the

signal

recei

ved

from

WWV.

If

the

adjustment

is

attempted

during

periods

that

WWV

is

modulated,

an

erroneous

zero

beat

may

be

obtained

with

the

modulating

frequency

instead

of

the

desired

carrier

frequency.

4-9.

SERVICE

OR

OPERATING QUESTIONS

For

any

further

information

regarding

operation

or

servlclllg

of

your

re-

ceiver,

contact

your

Hallicrafters

dealer.

The

Hallicrafters

Company

maintains

an

extensive

system

of

Authorized

Service

Centers

where

any

required

service

will

be

performed

promptly

and

efficiently

at

a

nominal

charge.

All

Hallicrafters

Authorized

Service

Centers

display

the

sign

shown

at

the

right.

For

the

location

of

the

one

nearest

you,

consult

your

local

dealer

or

telephone

directory.

Make

no

service

shipments

to

the

factory

as

the

Hallicrafters

Company

will

not

accept

the

reEponsibility

for

unauthorized

shipments.

The

Hallicrafters

Company

reserves

the

privilege

of

making

reVlSlOns

in

current

production

of

equipment

and

assumes

no

obligation

to

incorporate

these

revisions

in

earlier

models.

-14 -

Tf~

~allitrafters

$~~

communications

equipment

92Xl~Ol-C

SECTION

5.

ALIGNMENT

This

receiver

has

been

carefully

aligned

at

the

factory

by

specially

trained

personnel

using

precision

equipment.

Alignment

of

the

receiver

should

not

be

attempted

until

all

other

possible

causes

of

faulty

operation

have

been

investigated.

Alignment

should

not

be

required

unless

the

receiver

has

been

tampered

with

or

component

parts

have

been

replaced

in

the

r-f

or

i-f

stages.

Alignment

should

be

made

only

by

persons

familiar

with

communications

receivers

and

experienced

in

their

alignment.

Refer

to

Figs.

11

and

12

for

location

of

all

alignment

adjustments.

5-1. EQUIPMENT REQUIRED 5-2. INITIAL CONTROL SETTINGS

1.

Signal

generator

covering

50

kc

to

30

mc.

2.

Vacuum

tube

voltmeter

(VTVM)

or

other

high

impedance

DC

voltmeter.

3.

Output

meter

(or

AC

scale

of

VTVM).

Connect

output

meter

to

appropriate

speaker

output

terminals.

If

a VTVM

is

used,

connect

it

to

terminals

"500"

and

"G"

and

terminate

the

out-

put

with

a

dummy

load.

Band

Selector

. . . . . . . .

As

indicated

in

chart

Sensitivity

and

Volume

.........

10

(maximum)

AVC

and

Noise

Limiter.

. . . . . . . . . . . . . . . Off

AM/CW

-SSB

.......................

AM

Selectivity

............

As

indicated

in

chart

Response

.................

Lower

Sideband

Standby-

Receive

.................

Receive

Tuning

and

Bandspread

...

"

Gangs

half

meshed

Notch

Depth

.....................

" Off

5-3.

ALIGNMENT

PROCEDURE

Signal

Signal Band

Generator

Selector

Output

Selectivity

Step

Connections

Frequency

Setting

Connections

Setting

Remarks

50.5 KC IF

ALIGNMENT

1

High

side

directly

50.5

KC

.538 -1.58

VTVM

DC

probe

.5

KC

Remove

1st

conv.

oscillator

tube

to

alignment

point

"A"

(unmod.)

MC

to

alignment

point

V3

from

its

socket

to

prevent

(terminal

1 of T2).

See

"B"

(junction

0 f

signal

interference.

Adjust

top

Fig.

12.

Low

side

to

R48, R49,

andC81).

slug

of T3,

T4,

T5,

and

T6

(50.5

chassis.

See

Fig.

12.

Com-

KC

IF's)

for

maximum

indica-

mon

to

chassis.

tion,

maintaining

approx.

1

volt

reading

on VTVM.

ALIGNMENT

OF 1600 KC 2nd

CONY.

OSC. & 1650 KC IF'S

2 High

side

directly

1650

KC

"

Output

meter

a-

5

KC

Replace

V3

removed

in

Step

1.

to

alignment

point

"c"

(mod)

cross

appropriate

Tune

generator

slowly

thru

(stator

of

section

C1B

speaker

terminals.

1650

KC

to

determine

IF

pass-

of

main

tuning

gang).

(VTVM

to

align-

band.

Then

set

generator

to

Low

side

to

frame

of

ment

point

"B"

if

center

of

passband,

using

suf-

gang.

it

is

des

ire

d

to

ficient

generator

output

to

I

monitor

detector

obtain

approx.

1/2

watt

re-

voltage.)

ceiver

output.

If

no

output

is

I

obtained,

the

1600

KC

crystal

I

oscillator

may

not

be

oscillating

and

it

will

be

necessary

to

turn

up

the

generator

output

and

adjust

the

1600

KC

crystal

activity

adjustment

(top

slug

of

T9)

until

output

is

obtained.

Adjust

for

maximum

output

by

adjusting

the

sig-

nal

generator

frequency,

crystal

activity

(top

slug

of

T9)

and

the

1650

KC

IF's

(top

and

bottom

slugs

of

T1

and

T2).

Note

that

the

Signal

suddenly

disappears

when

the

crystal

activity

slug

is

turned

into

the

coil

and

gradually

drops

in

level

when

the

slug

is

backed

out

of

the

coil.

Set

the

crystal

activity

adjustment

(top

of

slug

of

T9)

for

half

output

on

the

gentle

slope

side

of

maximum

response.

Then

set

the

generator

as

near

the

center

of

the

IFpassband

as

possible

and

adjust

the

top

and

bottom

slugs

of

T1

and

T2

for

maximum

response.

Tune

through

the

passband

and

observe

the

shape

of

the

response.

If

it

is

symmetrical,

the

adjustment

is

completed;

if not,

reset

the

generator

frequency

near

the

center

of

the

passband

and

repeak

T1

and

T2.

ALIGNMENT

OF 1700 KC 2nd

CONY.

OSC.

3 I " I " I " I " I " I

Set

RESPONSE

control

at

"UPPER

SIDEBAND".

Tune

generator

slowly

thru

1650

KC

to

determine

IF

passband.

Then

set

generator

to

center

of

passband,

using

sufficient

generator

output

to

obtain

approx.

1/2

watt

receiver

output.

If

no

output

is

obtained,

the

1700

KC

crystal

oscillator

may

not

be

oscillating

and

it

will

be

necessary

to

turn

up

the

generator

output

and

adjust

the

1700

KC

crystal

acti-

ry

adjustment

(bottom

slug

of

T9)

until

output

Is

obtained.

Adjust

for

maximum

output

by

adjusting

the

signal

generator

frequency

and

the

crystal

activity

(bottom

slug

of

T9). Note

that

the

signal

suddenly

disappears

when

the

crystal

activity

slug

is

liurned

into

the

coil

and

gradually

drops

in

level

when

the

slug

is

backed

out

of

the

coil.

Set

the

crystal

activity

adjustment

(bottom

slug

of

T9)

for

half

output

on

the

gentle

slope

side

of

maximum

response.

-15-

IF SENSITIVITY CHECK

4

With

the

generator

modulated

30%

at

400

cycles

and

connected

thru

a .05 mfd

capacitor

to

the

grid

(pin

1)

of

the

1st

mixer

tube

V2,

the

IF

input

required

for

1/2

~att

receiver

output

should

be

approximately

20

micro-

volts.

This

assumes

the

crystal

activity

is

set

for

half

of

maximum

response

as

outlined

in

Steps

2

and

3

above.

RF

ALIGNMENT

•

Before

proceeding

with

the

RF

alignment,

check

•

Connect

the

output

meter

across

the

appropriate

the

tuning

dials

for

proper

indexing. Both

dials

speaker

t e r m

ina

1

s.

(Connect

the

VTVM

to

should

index on

the

marks

at

the

low

frequency

alignment

point

"B"

if

it

is

desired

to

monitor

end

with

the

gang

fully

closed.

the

detector

voltage.)

Maintain

a

1/2

watt

re-

•

Use

an

amplitude

modulated

signal.

ceiver

output.

•

Set

the

SENSITIVITY

and

VOLUME

at

"10"

•

Connect

high

side

of

generator

thru

330-ohm

(maximum),

A

VC

and

NOISE LIMITER

at

"OFF"

carbon

resistor

to

antenna

terminal

"AI".

Low

SELECTIVITY

at

"2

KC",

RESPONSE

at

side

to

"A2".

Connect

jumper

between

"A2"

"LOWER SIDEBAND", RECEIVE-STANDBY

at

and "G".

"RECEIVE,

and

BANDSPREAD" fully

counter-

•

The

oscillator

frequency

is

higher

than

the

sig-

clockwise.

nal

frequency

on

all

bands.

Band

Generator &

Selector Receiver Adjust

for

Step Setting Frequency Maximum

5

12

-34 30.0

MC

C66

(osc.

trimmer),

MC

C40

(mixer

trimmer),

and

C110

(antenna

trimmer)

" 14.0

MC

Ll1

(osc.

slug),

L8

(mixer

slug),

and

L1

(antenna

slug)

6 4.6 -13 11.5

MC

C59

(asc.

trimmer),

MC

C42

(mixer

trimmer),

and

C110

(antenna

trimmer)

" 5.1

MC

L12

(asc.

slug),

L9

(mixer

slug),

and

L2

(antenna

slug)

7 1.72 -

4.9 4.6

MC

C56

(asc.

trimmer),

MC

C44

(Mixer

trimmer),

and

C110 (antenna

trimmer)

" 1.925

MC

L13

(osc.

slug)

8 .538 -1.58 1.4

MC

C50

(osc.

trimmer),

MC

C45.

(mixer

trimmer),

and

CllO

(antenna

trimmer)

" .6

MC

C52

(osc.

padder)

BFO

ADJUSTMENT

Refer

to

Section

4-6.

NOTCH

FILTER

ADJUSTMENT

Refer

to

Section

4-7.

"S"

METER

CALIBRATION

• Make both

the

mechanical

and

the

electrical

"S"

meter

zero

adjustments.

See

section

6-5.

•

Connect

the

signal

generator

as

for

RF

ALIGN-

MENT

above.

Use

a

5.1

mc,

50uv, un

modulated

signal.

STEP

RESPONSE CONTROL P<l:>ITION

1

UPPER

SIDEBAND

2 LOWER SIDEBAND

NOTE

Some

interaction

may

occur

between

the

two

adjustments.

•

Set

the

receiver

controls

for

AM

reception

on

band

3 and

accurately

tune

in

the

signal.

•

Set

SENSITIVITY

to

"10"

(maximum),

AVC

to

"ON" and SELECTIVITY

to

"5 KC".

ADJUST FOR 50

UV

READING

ON

THE

"S"

METER

Bottom

of T9

Top

of T9

Recheck

the

readings

and

touch

up

both

adjustments

as

required

to

give

the

50

uv

reading

for

both

Upper

and

Lower

Sideband

response.

-16-

6AU6

CRYSTAL

CAL.

CliO

CI05

100KC

CRYSTAL

-------,

( I

I I

:

--

-~r--,

/-,

- 1

r)

I

101

LI5

1":,.1

'_...1

_________

1_

: I

6C4

, I

505KC

,----

-

IF

AMP

T9

(Q)

1600

KC

OSC

~

T2

{)

16~KC

1650KC 6BA6

1650

KC

IF AMP

RECTIFIER

8

VOLTAGE

REG

8

T60

50.5KC

o

6BJ7

DET.ANL.

a

AVC

. Showing

Location

of

Fig.

11.

Top

View of C:hassls

Tubes

and

Dial

Lamps

Alignment

Adjustments,

,

T7

o

S

o

S3A

PITCH CONTROL

KNOB

~_

I ,

LLs~~

c:::...~I_

I ,

, I

,

I I

:

c)

:

, I

1.._---)

~

La

SIB

Fig.

12.

. t

nts

and

Tu

es

Bo

ttom

View of

Chassis

Showing

bLOCatiOn

of

Alignment

AdJus

me

-17-

T7

®) ®)

AUDIO

OUTPUT

8

92C5018

C44

0:::

W

x

::2'

C50

u

Cfl

o

C56

92C5019

SECTION

6

SERVICE

DATA

6-1. TECHNICAL SPECIFICATIONS

TUBES

....•.

12

plus

voltage

regulator

and

rectifier

SPEAKER

OUTPUT.

. . . . . . . . . .

..

3. 2 and 500

ohms

HEADPHONE OUTPUT

..

500

ohms

(See

Section

2-6.)

ANTENNA

INPUT.

. . . . . . . . . . . . . . . . . . . .

..

300

ohms

PHONO INPUT

.................

High

impedance

*POWER SOURCE

......

,

105-125

volts,

50/60

cycles

POWER CONSUMPTION. . . . . . . . . . . . . . .

..

88

watts

RECEPTION

...............•...

AM,

CW,

and

SSB

INTERMEDIATE FREQUENCIES.

..

(Double

Conver-

sion):

50.5

KC and

1650KC

DIMENSIONS

(overall).

8-7/8"

x

18-1/2"

x 11" deep

SHIPPING WEIGHT

..................

41-1/2

lb.

NET WEIGHT

.......................

34-1/2

lb.

Band

1

2

3

4

FREQUENCY COVERAGE

Frequency Range

.538 -1.58

MC

1.72 -

4.9

MC

4.6 -13.0

MC

12.0

-

34.0

MC

Calibrated

Band

Spread

80M

40M

20, 15, 11-10M

*Provisions

are

also

included

for

operation

from

an

ex-

ternal

DC

power

source.

(See

Section

2-4. )

6-2.

50.5

KC

IF

SYSTEM,

Fig.

13

shows

the

type

of

coupling

used

in

the

50. 5

kc

IF

system.

Note

that

inductive

coupling

is

avoided

by

careful

shielding

of

the

IF

coils

and

signal

transfer

oc-

curs

only

through

capacitance

and

resistance.

By

increas-

ing

the

value

of

"C"

and

"R",

the

selectivity

is

made

more

broad

while

by

decreasing

their

values,

the

selectivity

is

made

more

sharp.

The

proper

values

of

HC"

and

"R"

are

switched

in

the

circuit

by

means

of

the

SELECTIVITY

control.

"R"

varies

the

"Q"

of

the

tuned

circuit

and"

C'

V5

2ND

MIXER

68A6

B+

varies

the

coupling.

This

R-

C

coupling

arrangement

af-

fords

a

more

accurate

means

of

selectivity

control

than

that

readily

obtainable

by

any

other

method.

6-3.

CHASSIS

REMOVAL

The

chassis

and

front

panel

assembly

are

removable

from

the

cabinet

as

a unit

by

removing

two

screws

at

each

side

of

the

front

panel

and

the

six

screws

on

the

under-

side

of

the

cabinet. When

removing

the

chassis

from

the

cabinet,

care

should

be

taken

not

to

damage

the

brass

adjusting

screws

on

the

oscillator

slugs

(L-1l-12-13-14).

Refer

to

Figure

12

for

location.

6-4.

TUBE

and DIAL LAMP

REPLACEMENT

To

gain

access

to

the

tubes

and

dial

lamps,

raise

the

hinged

top

.

cover

of

the

cabinet.

The

tube

locations

and

their

functions

are

shown in Fig. 11.

6-5.

"S"

METER

ADJUSTMENTS

The

"S"

meter

has

two

adjustments,

one

electrical

andthe

other

mechanical.

The

mechanical

adjustment

is

accessible

by

rotating

the

"h"

insignia

on

the

front

of

the

''8''

meter

to

one

side.

(The inSignia

pivots

at

the

top. )

The

mechanical

adjustment

has

been

accurately

set

at

the

factory

and will

normally

not

require

any

further

ad-

justment.

Adjustment

can

be

made,

if

required,

by

turn-

ing

off

the

receiver

and

carefully

rotating

the

adjustment

screw

until

the

meter

pointer

is

in

line

with

the

right-hand

index

mark.

The. e1e c t

ric

a I

adjustment

is

made

by

carefully

turning

the

"S"

METER

ADJ

control

at

the

rear

of the

receiver

(Fig.

4),

until

the

pointer

is

in

line

with

the

left-hand

index

mark.

The

electrical

adjustment

should

be

made

with th€

receiver

on,

antenna

terminals

shorted,

SENSITIVITY

at

"10",

AM/CW-SSB

switch

at

"AMIt, AVC

switch

at

"ON", and R EC E I VE - S

TAN

D

BY

switch

at

"RECEIVE".

The

settings

of

the

remaining

controls

do

not

affect

the

"S"

meter

reading.

V6

50.5

KC

IF

AMP

6BA6

B+

1/3

V7

DET

1/3

6BJ7

Fig.

13.

Equivalent

Schematic

Diagram

of

50. 5

KC

IF

System

92C2378

-18-

3

NOTE

-

BAND

SPREAD

GANG

FU

LLY

CLOSED

~~

____

~

______________

~

____

~5~~~

\OJ

6

Fig.

14.

Dial

Cord

Stringing

Diagram

9282383

6-6. DIAL

CABLE

RESTRINGtNG

To

restring

the

bandspread

dial

cable,

first

remove

the

front

panel

from

the

cabinet

by

removing

the

control

knobs,

the

toggle

switch

and

Phones

jack

mounting

nuts,

the

Sensi-

tivity

control

mounting

nut,

the

two

screws

at

each

side

of

the

front

panel,

and

three

screws

on

the

underside

of

the

front

panel.

Leave

the

bandspread

dial

in

place

but

remove

the

main

tuning

dial

to

gain

access

to

the

pulley

on

the

band-

spread

gang.

This

is

accomplished

as

follows

(Refer

to

Fig.

15.):

(1)

Remove

the

two

screws

at

the

front

of

the

dial,

(2)

Loosen

the

pointed

set

screw

to

the

right

of

the

dial,

(3)

Disengage

the

idler

gear

from

the

dial

by

lifting

upward

on

the

idler

gear

mounting

plate

and

(4)

Carefully

remove

the

dial.

Before

restringing

the

dial

cable,

attach

the

tension

springs

to

the

cable,

rotate

the

Bandspread

control

fully

clockwise,

and

set

the

bandspread

gang

in

its

fully

closed

position.

At-

tach

the

spring

at

one

end

of

the

cable

to

position

"1"

on

the

bandspread

gang

pulley

as

shown

in

Fig.

14

and

follow

the

stringing

sequence

"1"

through

"10".

After

stringing

is

completed,

rotate

the

Bandspread

con-

trol

fully

clockwise

and

check

the

position

of

the

bandspread

gang

and

the

illdex

marks

at

the

low-frequency

end

of

the

dial.

The

gang

should

be

fully

closed

and

the

index

marks

should

be

vertical.

If

the

bandspread

gang

is

not

fully

closed

with

the

Band-

spread

control

set

fully

clockwise:

1.

Loosen

the

two

set

screws

that

secure

the

pulley

on

the

bandspread

gang

shaft.

2.

Holding

the

Bandspread

control

fully

clockwise,

set

the

gang

in

its

fully

closed

position

by

turning

the

gang

shaft,

and

then

tighten

the

set

screws.

If

the

index

marks

at

the

low

end

of

the

bandspread

dial

are

not

vertical

with

the

Bandspread

control

set

fully

clockwise:

(Refer

to

Fig.

15)

-19-

1.

Check

the

position

of

the

gang

as

outlined

above

and

make

the

adjustment

if

required.

2.

Loosen

the

two

set

screws

at

the

rear

of

the

dial

mounting

collar.

3.

Loosen

the

pointed

set

screw

to

the

left

of

the

band-

spread

dial.

4.

With

the

right

hand,

hold

the

cam

assembly

in

the

posi-

tion

shown

in

Fig.

15.

with

the

thumb

of

the

left

hand

lift

the

idler

gear

mounting

plate

upward

to

disengage

the

dial,

and

with

the

index

finger

of

the

left-hand

care-

fully

rotate

the

dial

until

the

index

marks

at

the

low-

frequency

end

are

vertical.

After

the

dial

is

properly

positioned,

release

the

idler

gear

and

tighten

the

two

set

screws

on

the

collar.

5.

Turn

down

the

pointed

set

screw

until

it

just

touches

the

idler

gear

mounting

plate.

If

the

screw

is

turned

down

too

far,

the

dial

will

not

rotate

freely;

if

not

turned

down

far

enough,

the

idler

gear

will

not

engage

the

dial

properly

and

the

dial

will

have

a

tendency

to

slip.

6.

Rotate

the

Bandspread

control

fully

clockwise

and

check

the

position

of

the

index

marks

at

the

low-fre-

quency

end.

If

they

are

still

not

vertical,

it

will

be

necessary

to

repeat

Steps

2

through

5.

To

replace

the

main

tuning

dial:

(Refer

to

Fig.

15)

1.

Rotate

the

main

tuning

gang

to

its

fully

closed

position.

2.

Lift

the

idler

gear

mounting

plate

upward,

replace

the

dial

with

the

index

marks

at

the

low-frequency

end

fac-

ing

upward,

and

fasten

it

in

place

by

means

of

the

two

front

screws.

3.

With

the

index

finger

of

the

left

hand,

hold

the

main

tuning

gang

in

its

fully

closed

position,

with

the

right

hand

lift

the

idler

gear

mounting

plate

upward

to

dis-

engage

the

dial,

and

with

the

thumb

of

the

left

hand

carefully

rotate

the

dial

until

the

index

marks

at

the

low-frequency

end

are

exactly

vertical.

When

the

dial

is

properly

positioned,

release

the

idler

gear

and

tighten

MAIN

TUNING

o

the

two

set

screws

at

the

rear

of

the

dial

mounting

collar.

4.

Same

as

Step

5

on

page

19.

5.

Rotate

the

Tuning

control

fully

clockwise

and

check

the

position

of

the

index

marks

at

the

low-frequency

end.

If

they

are

not

exactly

vertical,

it

will

be

necessary

to

re-

peat

Steps

3

and

4.

BANDSPREAD

o o

CAM

ASSEMBLY

DIAL

MOUNTING

COLLAR

92C2395

Fig.

15.

Front

View of

Gear

Drive

Tuning

Mechanism

ANTENNA

~

1650

KC

:

1650

KC

505

KC

5Q.5KC

L_

_ _

___

_

______

-1

____

-

-----------

--

- -

~V'-----l

1600

KC"(LOWER

SIDEBAND

RECEPTION 1

1700Ke

(UPPER SIDEBAND

RECEPTION

J

AUDIO

Fig.

16.

Block

Diagram

of

Receiver

-20-

I

+

I

L

1/3

V7

113

DET

1/3

6BJ7

1/3

6BJ7

150.5I<C

PHONES

Hallicrafters SX-100 MARK IA User manual

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