Heathkit GR-61 Assembly Manual

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FM

PORTABLE

RADIO

MODEL

GR.6I

tii

4

{

TYPICAL

COMPONENT TYPES

This

chart

is a

guide

to commonly used types

of

elec- tions should

prove

helpful in identifying

most

parts

and

tronic

components. The symbols and

related illustra-

reading the

schematic diagrams.

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EARTH GROUND

CHASSIS GROUND

CONOUCTORS

Assembly

and

Operation

of the

FM

P O

RTAB

LE

RAD

IO

MODEL

GR-61

'===*=,

HEATH

COMPANY

BENTON

HARBOR,

MICHIGAN

TABLE

OF

CONTENTS

Specifications.

. .

.

Introduetion.

Circuit

Description.

Parts

List.

Step-By-Step

AssemblY

Circuit

Board

AssemblY.

.

.

Right

End

Plate

Parts

Mounting.

Left End

Plate

Parts

Mounting.

Circuit

Board

Mounting.

. .

Wiring Circuit

Board

To

End

Plates.

.

..

Final

Wiring

Final Assembly.

.

.

Initial

Test

And

Adjustment.

. .

Cabinet

AssemblY.

Operation.

In

Case

Of

DifficultY

Troubleshooting

Chart.

Introduction

To

Transistors.

.

.

Glossary

Of

Radio

Terms.

Circuit

Board

X-RaY

View.

(fold-out

from

Page).

.

. .

.

Cqyrlghto

t962

12/3O/66

2

3

3

D

30

31

SPECIFICATIONS

Tuning

Range.

Intermediate

Frequency (IF').

. .

Sensitivity.

Controls.

Transistors.

Antenna.

Speaker.

Batteries.
Normal

Battery

Life.

.

Accessory

Jack.

.

Size.

.

Net

Weight.

The Heath

Company

reserves the

right

to discon-

tinue

instruments

and to

change specifications

at

any

time

without

incurring any

obligation

to

88 to

108 megacycles.

10.7

megacycles.

3

uv for

20 db

quieting

(average),

5 uv for 20

db

quieting (maximum).

(Measurements

takenin

aligned

condition.

)

Volume,

Tone,

and AFC.

3

-

2N174?

4

-

2Nt274

1

-

2N24e5l

1

-

2N26711

in FM

tuning

unit

1

-

2N26541

Collapsible

whip

with

provisions

for

external

300 Q

antenna.

4r x

6t'

oval,

permanent

magnet

type.

Six l-l/2

volt

size

C

cells.

300-500

hours.

Earphone

or

hi-fi

output.

9-L12"

wide x 1-l/Q,,high

x 4"

deep.

3 lbs.

incorporate

new features

in instruments

pre-

viously

sold.

I

*

)

_--I

l@l

n*"g

INTRODUCTION

Your

new

FM Portable

Radio

featuresadepend-

able

10-transistor

circuit,

housed

in

an attractive

imitation-leather

case.

The

front

of

the

case is

made

of durable

high-impact plastic.

Exceptionally

high

quality

is designed

into

this

Radio,

as

evideneed

by ttre

preassembled

and

prealigned

FM

tuning

unit, and

the

prealigned

IF

and

ratio

detector

transformers.

-ThreJIF-

limiter

stages,

plus

a ratio

detector

combina-

tion

with

AFC, provide

stable

FM

reception. The

push-pull

audio

power

amplifier

circuit delivers

more

than

adequate power

for the

4" x

6"

speaker

to give

large-room

sound

coverage.

CIRCUIT

DESCRIPTION

The

preassembled

and

prealigned

FM tuning

unit contributes

to

ease

of

assemblyandinsures

consistently

good

FM

performance.

A

heavy-

duty

circuit

board

is used

to further

simplify

assembly

of

the

kit.

If

you

are not

familiar

wlth

electronic

circuitrv

and

terminology,

you

may

find it helpful to

reai

the

I'Introduction

To

Transigtorsr

and

"Glossary

Of

Radio

Terms"

beginning

on

Page

2?

of

ttre

manual.

This

information

should

prove

helpful

in

understanding

how

your

Radioworkswhenyou

read

the

following

Circuit

Description.

The

circuitry

of the FM

Portable

Radioconsisrs

of

the

RF, IF-limiter,

ratio detector,

and

audio

sections.

For

simplicity,

each

section will

be

discussed

separately,

Refer

occasionally

to the

Schematic

Diagram

while

reading

tris

descrip-

tion.

To

help

in

reading

the

Schematic,

the

letter-

number

designations

for

t}e

circuit

parts

are

number

coded

as follows: #1

to

gg

for the FM

tuning

unit, and

#100 to

200 forthecircuit

board

and

chassis.

For

example,

resistor

R3 ig in the

FM

tuing

unit, and

resistor

R,103

is

onthe cir-

cuit

board.

NOTE:

Refer

to

the

"Kit

Builders

Guide"

for

complete

information

on unpacking,

parts

identi-

fieation,

tools,

wiring,

soldering, and

step-by-

e

RF

SECTION

The

RF

section

contains

the

RF amplifier,

oscillator,

and

mixer

stages,

all

in

i

pre-

assembled

and

prealigned

tuning

unit.

FM

signals

from

the

antenna

are applied

to

transformer

T1

,

which

matches

the

antenna

to the

first

section

of

the tuning

capacitor,

C1A. This

portion

of

the

tuning

capacitor tunes

ttre

emitter

circuit

of RF

amptifier

Ql

to the

desired

FM

station

frequency.

C1B,

the

second

section

of

tlte

tuning

capacitor,

tunes

the

collector circuit

of

Q1

to the

same

station

frequency.

Q2

is

operated as

a feedback

tuned-collector

oscillator at

10.?

megacycles

above the

fre-

quency

of

the

desired

FM

station. The

ampli-

fied

FM

station frequency

from

Q1,

and the

oscillator frequency

from

Q2

are mixed

in

Q3

to

provide

a

difference

frequency

of

10.7

meg-

acycles. This

difference

frequency

is coupled

tirough

transf

orme r T2,

out

of

the

preas

se mble d

tuning

unit,

to the

first IF

amplifier,

Q4.

I

t

I

l

I

I

1

-l

I

{

n"u"a

@EGBI

The circuit of

the

P.E.C.

includes

a

de-empha-

sis

network

to

compensate

for high

frequency

pre-emphasis

that was

added to

the transmitted

audio

signal;

it thus

provides

a

flat audio

fre-

quency

response.

This network

also attenuates

frequencies

above

the audio range.

The audio

output

signal

of

the ratio

detector is

applied

both

to

Q7,

the

emitter

follower

and, as

an

AFC

voltage,

to

Q2

oftheFMtuning

unit.

Any

shift of

the

IF from

the

10.7

megacycle

center

frequency

appears

as

a DC voltage

which

is ap-

plied

to

diode D1;

this is

commonly

called

AFC

voltage.

The

DC

voltage

shift on

D1 in

turn

changes

the oscillator

capacity,

thereby ef-

fectively retuning

it and causing

it to

track the

particular

station

that is

being

received.

AUDIO

SECTION

The audio signal

from

the ratio

detector is

applied to

Q7,

the emitter

follower,

which acts

as

a matching networkbetween

the

ratio

detector

and

the Volume control.

After

the Volume control,

the audio signal

is amplified

bydriver

amplifier

Q8

and

then

to the

Tone

control

and

to driver

transformer

T6. Transformer

T6

couples

the

audio signal

to

Q9

ahd

Q10,

ttte

push-pull

audio

amplifier stages.

From

Qg

and

Q10

the signal,

is coupled

to the speaker

and

earphone

jack

through

T?,

the audio output

transformer.

When

an

earphone is

plugged

in,

the built-in

speaker

is automatically

disconnected

from

the

circuit

and

the

audio signal

goes

instead

to the ear-

phone.

Operating

power

is supplied

by six

1-1/2

volts

size

C

flashlight

batteries.

IF-LIMITER

SECTION

The

10.?

megacycle signal

from

the

FM tuning

unit is

appliedto

Q4,

the

first IF amplifier.

From

Q4,

the

IF signal

passes

through

transformer

T3'

which

passes

only

the difference

frequency

of 10.?

megacycles,

to

Q5,

the

second

IF amplifier.

After

additional amplification

in

Q5,

the signal

is

applied

through T4, the second

IF transformer,

to

limiter stage

Q6,

which limits on

all but

the

weakest

signals.

Stages

Q4

and

Qb

act as

IF amplifiers

for

weak

signals,

and

as limiters

for

strong

signals.

Limiter

stages

are used

to remove

any

AM

(amplitude

modulation)

of

the IF signal,

and

to

limit

the signal

to

the

proper

level

for

the ratio

detector.

The IF signal

from

limiter

Q6

is next

applied

to ratio

detector transformer,

T5.

RATIO DETECTOR

Ideally,

the IF

signal

applied

to

the ratio

de-

tector should be of constant

amplitude,

but con-

tain

variations

in frequency

which

correspond

to

tfie audio signal being

transmitted

by

the

FM

station.

The

amount of

frequency

deviationfrom

the center

frequency of

10.7

megacycles

de-

termines

the amplitude of

the resulting

audio

signal.

The number of

times

per

second

thatthe

IF

signal

deviates from 10.?

megacycles

de-

termines

the resulting

audio

frequency.

The

combinatlon of

diodes D3, D4, and

transformer

Tb detect frequency variations

in the

IF

signal,

and

change

these variations

into

anaudiosignal.

Most of

the resistors

and capacitors

used

inthe

ratio

detector

are encapsulated

in a

P.E.C.

(pack-

aged electronic

circuit).

The

use of

this

P.E.C.

eliminates

any variations

in

performance

that

could

result

from

different

wiring

techniques.

@EE@l

P"e"s

PARTS

LIST

The

numbers in

parentheses

in the Parts List

are keyed

to the

numbers in the Parts drawings

to aid in

parts

identification.

PART

No.

PARTS

Per

Kit

DESCRIPTION

4.7

Q

(yellow-violet-gold)

10 Q

(brown-black-black)

68 A

@Iue-gray-black)

220 Q

(red-red-brown)

820 A

(gray-red-brown)

1

KO

(brown-black-red)

1.2

KO

(brown-red-red)

2.?

KO

(red-violet-red)

3.3 KO

(orange-orange-red)

4.1 KA

(yellow-violet-red)

6.8 Kft

(blue-gray-red)

10 KO

(brov'n-black-

orange)

t2 KQ

(brown'red-orange)

15 KO

(brown-green-orange)

18

KO

(brown-gray-orange)

22 KA

(red-red-orange)

68

Kf)

(blue-gray-orange)

1 00 KO

(brown-

black-

yellow)

1 megohm

(brown-black-

green)

PART

PARTS

No.

Per

Kit

Controls-Switch

(5)

10138- 1-

"

(6)

1e-81

(?)

60-18 1

Choke-

Transf

ormers-

Diode

DESCRIPTION

100

KO linear

control

10 KQ

control

with SPST

switch

SPST

switch

Resistors

(1)

1:T20

t-4L

L-2

t-45

1-8
1-9

1-

10

1-

13

t-r4

1- 16
1- 19

L-20

1-109

L-21
1-69

t-22

1-60

r-26

1-

35

Capacitors

(2)2

-

2t-46

2t-94

(3)

25-54

(4)

25- 11 5

25-116

25-tl?

25-11 1

(8)

45-35

(e)

sr-sz

51-98

(10)

52-57
53-6

(11)

56-26

(81

(10)

2

1
1

2

1

I

1.?

ph

choke

Driver transformer

Output

transformer

IF transformer

Ratio detector transformer

Crvstal

diode

1

I

I

1

4

I

2

1

210

ttttf

disc

ceramic

.005

pfd

disc ceramic

.05

pfd

disc

ceramic

10

pfd

15

V tubular

electro-

lytic

10

pfd

15

V

electrolytic

50

pfd

15

V

electrolytic

100

pfd

15

V

electrolytic

1000

pfd

15

V tubular elec-

trolytic

tzt

1-7

\\=t-

/-

{4r lf-----------v

l-

^r--

J"

'::-

a

{

n'u"u

@EEFI

PART

No.

PARTS DESCRIPTION

Per

Kit

PART

No.

PARTS

DESCRIPTION

Per

Kit

Transistors

4t7

-10

1

411

-7t

1

411

-72

1

411

-57

3

tt7-2

1

2N2671

transistor

tuning

unit)

2N2654 transistor

tuning

unit)

2N2495 transistor

tuning

unit)

2Nl74? transistor

Transistor

package

contain-

ing four

part

no.417-21,

type

2N1214 transistors

3-48

x 1/4" screw

4-40

x

1/8" setscrew

6-32

x 3/16" screw

6-32

x l/4" screw,

phillips

head

6-32 x L/4"

sctew, binder

head

6-32

x

3/8"

screw

6-32

x

3/8"

self-tapping

screw

6-32 x l/2"

screw

(in
(in
(in

Hardware

(cont?d.

FM

(18)

254-?

I

(1e)

254-e

2

FM

(20)

254-1 1

(2r)

254-14 2

FM

(22)254-4

1

#3

lockwasher

#4 lockwasher

#6 lockwasher

Small

control lockwasher

Large

control

lockwasher

i

t-

t

I

!

I

Hardware

(1)

250-4e

(2)

250-156

(3)

250-138

(4)

250-22s

(5)

250-56

(6)

250-8e

(?)

250-106

(8)

250-10

343-?
344-50

344-1

6

344-t5

346-1

[

]

${ilrlr

(2)

fo

(3}

frfril

ro

flinm

,rr,-rz+rQ2

,-,F

(16)@

e7l

I

^

(5)

^

(61

^

(71

,

(8)

fl,',ii',',i

l,p,i,'*rr

gF**

t}.**t

I

2

8
3

d

2

n

4

@

@

4

2

1
1

2

4

10

4

2

wire
wire
wire

(s)

252-r

(10)

252-15

(11)

252-3

(L2)

252-22

3-48

nut

4-40

nut

6-32

nut

6-32

speednut

(ls)

@

(16)

(l

z1

@

g

(r

a1

(l

e)

(20)

(21

)

ezl

@@@@@

.

r3)

255-11

(24)

25e-rt

(25)

25e-12

(26)

455-31

(2?)

258-30

Metal Parts

(Zg)

tOO-rr,rarO

r

(2e)

1oo-M41?

1

(30)

zo4-Mb1?

1

Cable-Wire-SleevinE

Tapped

spacer

Spade

lug

Large

solder lug

Antenna

bushing

Battery

spring

Length

shielded cable

Length

black hookup

Length

stranded

red

Length

stranded black

Length sleeving

Switch

lever

Bottom

circuit board

bracket

Top

circuit board bracket

ota:lno)g rlr).

urt&

Small control

nut

Large control

nut

Flat

washer

Thin

nylon shoulder

washer

Thick nylon

shoulder

washer

(13)

(14)

(13)

252-3e

(r4)

252-7

(15)

253-45

(16)

?5-18

(1?)

2b3-Eo

3

1

2

1

I

r*

Page

T

PART

No.

PARTS

DESCRIPTION

Per

Kit

Metal Parts

(cont'd.)

(1)

mA:IFI0--T------Tntenna bracket

(2)

205-M391

(3)

205-M392

(4)

46e-Ml3

85-51F831

92-9
93-8

110-14

391

-23

401-19

(6)

431

-6

(?)

434-110

(8)

436-16

462-81

462-r8r

462-89

462-175

490-1

490

-2

3

tr42-42

390

-1

58

(e)

214-30

(10)

i214-31

(1

1)

?3-4?

331

-6

595-593

Right

end

plate

Left end

plate

Batterv contactor

1
1
1

I
I

1
1

I

1
1
1

7

I

1

I

1

2

1
1
1

1
1

2
3

1

P.E.C.

(packaged

electronic

circuit)
Circuit

board

Cabinet

front

Leather

case

FM tuning

unit

Nameplate

Spealer

2-screw terminal strip

Transistor

socket

Earphone

jack
Small tuning larob
Large tunlng knob

Volume

knob

Tapered knob

Alignment tool
Allen

wrench

Collapsible

antenna

Battery

label

Battery

holder

Battery

holder end

Sponge

rubber

pad

Solder
Manual

,?"€r

\-----

_.-TOP

SIDE

,f

NOTE:

SOCKETS MUST

@@

11.

(

)

Conn

AFC.

circr

(

)

Referring

length

of

CUT

THE

CAE

BELOW.

PRE

TAKING CAR€
OF

THE

SHIEI

INSULATION.

PEEL OFF

TI'

THIN WIRES

(

Defoi

Detoil

lA

dj,

BE INSERTED FROM
THE TOP

(LETTERED}

SIDE

OF THE CIRCUIT

BOARD.

THIS IS

THE

SIDE

OPPOSITE THE

METALIC FOIL.

,,1,::

ir

REMOVE

THE

SMALL

IYIRES

AMOUNTS

OF

LEAD

ANO

TH

SOLDER

--{

v

L2.

(

)

Ator

w'ire

(s-1)
othe:

heat

may

resu

leadr

conn

KEYWAY

ttB

Detqil

lC

.:1::

t1.r

;::1i

Page

8

Before starting

Builders

Guide

wiring,

solderit

procedures.

CIRCUIT

BOARI

(

)

Referring

t

mount

the I

circuit

boal

lettered

si<

socket

Posi

of

the

circu

align

ProPe

all

four

Pir

lrcard.

Be

r

unused

hole

(

)

Referring
tapped spa
the

circuit

These

spac

keep

it le'

rePositione

Proceed

to

Pic

steps

surroundi

Refer

to

Picto

(

)

Remove

th

lettered

sit

them on

th

using

tlte s

PICTORIAL

3

PICTORIAI

I

PROCEED

TO

PICTORIAL

2

STEP.BY.STEP

ASSEMBLY

|@E

11.

(

)c

A

ni

Before

starting

to

assemble

this

kit,

readthe Kit

Builders

Guide

for

complete

information

on

wiring,

soldering,

and

step-by-step

assembly

procedures.
CIRCUIT

BOARD

ASSEMBLY

(

)

Referring

to

Detail

1.{

(on

Pictorial

1),

mount

the

seven transistor

sockets

on

the

circuit

troard. Insert

the

sockets from

the

lettered

side

of

the

board. Be

sure each

socket

positioning

tab fits

into the keyway

of

the

circuit

board, and thatthe

socketpins

align

properly

with

the foil

pattern.

Solder

all

four

pins

of

each socket to the

circuit

board.

Be

careful not to

solder

any

of

the

unused holes

in the

circuit

board.

(

)

Referring

to

Detail

18, mount

the

four

tapped

spacers

on

the

lettered

side of

the

circuit

board.

Use

6-32

xg/g,,screws.

These

spacers

will

support

the

board

and

keep

it

level.

They

will

be

removed

and

repositioned

later.

Froceed

to

Pictorials

1 and

2 and

perform

the

steps

surrounding

the

illustrations.

Refer

to Pictorial

3

for the

following

steps.

(

)

Remove

the

four

tapped

spacers

from

the

lettered

side

of the

circuit board.

Then

mount

them

on

the

foil

side

of

the

circuit

board

using tlle

game

screws.

PICTORIAL

3

NOTE:

When

using

hookup

wire

in the

following

steps,

cut the

required

length

of

wire

and

strip

l/4

of. insulation

from

each end.

Connect

one

end

of thefollowingwirestottre

eir_

cuit board.

The

correct

length

is

given

at the

beginning

of each

step.

The

free

ends

of

tlese

wires

will

be

connected

later.

1.

(

2.(

3.(

4.(

5.(

6.(

t.

\

8.(

e.(

10.

(

)5"

)3"

)2"

)

4-t/4"

)4"

)

r-3/4,'

I

L-3/4"

)

3-r/2,,

)2"

)

2-3/4"

LENGTH

FROM

TONE-3

(S-1)

vol-z

(s-1)

vol-1

(s-l)

TONE-1 (S-1)
TONE-2 (S_1)
BATT

+

(S-1)

vol-3

(s_1)

AFC-z (S-1)

rF

-

(s-1)

IF

+

(S-1)

(

)

Referr

Iength

CUT

THE

BELOW. I

TAKING

C,

OF

THE SF

INSULATII

PEEL

OFF

THIN

WIRI

REMOVE

TI

SMALL

WIF

AMOUNTS

(

L

E A D A

ND

SOLDER

12.()

At

w'i

(s.

ou

he

mi

re

lei

co

F-+::i

l

/_---"1

\-f",

\l= JJ

\n*}n

\\./

oi^./

ilVffi

LJ^II

&J

ra/

vt

I@EEEEEEFI

nu*"

n

11.

(

)

Connect

a 4-3f4,'

wire

between

points

AFC-1

(S-1)

to

AFC-I

(S-1)

on

tne

circuit

board.

Position

as

shown.

(

)

Referring

to Detail

3A,

prepare

a

J-t/Z',

length

of shielded

cable as

shown.

12.

( ')

At

oneendofthecable.connecttheinner

wire to AGC

(S-1)

andtheshieldtoGND

(S-1)

of

the

circuit

board. Leave

tlre

other end free.

Be

careful not to

over-

heat the

cable

conductors

since this

may

cause the

inner

insulation to

melt,

resulting

in

a short

circuit.

Grip the

leads

with

pliers

between

the

solder

connection

and the

insulation.

13.

(

)

Remove

l/4t' of insulation from

each

end

of a

9" Iength

of

stranded black

wire.

Twist

the

separate

strands

to-

gether

tightly

at each

end

of

the

wire.

Then

apply

a

small amount

of

solder

to

each

end toh6iTifre

strands

tosether.

(

)

Connect

one end

of

this

g"

black

wire

to

BATT-

on

the

circuit

board

(S-1).

The

other

end

will

be

connected

later.

14.

(

)

RFC-1.

Cut

one lead

length

of a RF

choke

(#45-3b)

to

1",

place

B/4,'

of.

sleeving

over this

lead

and

connect it

to

RFC-I

on

the

circuit

board

(S_1).

Leave

the

other end

free.

(

)

Ctip

off

all

excess

leads

at the

soldered

joints

on

the

foil

side

of

the

circuit

board.

NOTE:

When

mounting

transformers

in the

fol-

lowing

steps,

carefully

align the

pins

of each

transformer

with the

holes

of

the

circuit

board.

The

spacing

of

the

transformer

pins

and

the

holes

of

the

circuit

board

are

such that

when

alisned

properly

ttrey

will mount

easily,

withoutforJing.

15.()

16.()

1?.()

T7.

Install

the

outputtransformer

(#b1-

98) at T?.

Solder

all

5

pins.

T6. Install

the driver

transformer

(#51-97)

at

T6. Solder

all

5

pins.

T3.

Install

one

of

the

IF transformers

(#52-51)

at

T3.

Solder

all

8

pins.

18,

(

)

T4.

Install the

remaining

IF trans-

former

(#52-51)

at T4. Solder

all 8

pins.

19.

(

)

T5.

Install

the

ratio detector

trans-

former

(#53-6)

at TF. Solder

all?pins.

(

)

Check

to

see

that

all the

connections made

on the

circuit

board have

been

soldered.

Set the

board

aside temporarily.

ll

v

t

l

t

i

:

I

;

I

I

I

I

CUT THE

CABLE

ACCORDING

TO

THE DIMENSIONS

BELOW.

PREPARE

EACH END

A5 SHOIVN.

IAKING

CARE

NOT

TO

CUT THE VERY THIN WIRES

OF THE SHIELD

LEAD,

REMOVE

THE

OUTER

INSULATION.

PEEL

OFF THE

FOIL AND

STRAIGHTEN

OUT

THIN WIRES

OF

THE SHIELO

LEAD.

REMOVE

THE

INNER

INSULATION

AND TIVIST

THE

SMALL

IYIRES

OF THE

SHIELO

LEAD.

APPLY

SMALL

AMOUNTS

OF

SOLDER

TO THE ENO

OF THE SHIELO

LEAO AND

THE

INNER

LEAO.

(

)M

b:

th

sl

s(

la

()M

al

p

()M

#i

Set U

LEFT

Refer

(

)M

oo

[-__l,

tl

-r-T

8ru r3z+"

Ao

V

€

fi,

AFC

swtTcH

c

f-l

u

I lAFc-r

tl

tl

r

I te I

\,/

,

r|\

ea

De-

nfc

AGC

NIT

6)

FM

ING

U

@

-t

a

Qz

B(

t-l

c

?

SOLDE

R

LUG

,-l

N

E

2Nt747

Q4

\Yd

'

tF+

N

..+iiii

@)

,lT-l

@

@

k1

oo

tl

-t-l-

8ru rZza"

Ao

t\)

{-e

il,

AFC

swlTcH

a

nu

I lAFc-

L_l r)

a)

\__/

|

(r)

o-a

oC-

nf0

AGC

TUN

NIT

6)

FM

ING

U

@

-l

a

€z

B(

t-ic

?

SOLDE R

LUG

lt

c-l

I/ve I

,/

'C+

RF

1__r

N

E

2Nt747

o4

0r-d

'

rF+

N

..,:r;jiil

-.i..:rj:f

4E

@

@

k1

(

)M

br

tt

s1

st

Ia

()M

AJ

p

()M

#1

Set

tl

LEFT

Refer

()M

ll

n O

voL-z

o

o

o

YY ,....: L

rooo

llFD

@

NTROL

TONE

CONTROL

Page

10

6-32

SPEEDN

FLAT

SIDE

6-32

NUT-\

LOCKWASH

ER

-

T

ER

MIN/A

RIGHT

END PLA'

Refer

to

Detail

(

)

Mount

two

6-

plate.

Be

surr

is

positioned

NE

o

TO

-3

lNr274

A

L-/€

EQ5

-\n

,-\TONE-lc

r\ Vr(f

I l,'^\ | I

\\_/rfrffi

BATT_

f]

-i-

\7-

O

O

O

a1

OLJ

2N1747

A

())C

BGF

Y

:fJ

Deloil

1F

PICTORIAT

6-32

X3lt6"scREW

6-32

SPEEDNUT

AFC

SWITCH

*T

6

LOCKWASHER

6-32

NUT

THIN

NYLON

SHOULOER

WASHER

AN

TE

NNA

BUSHING

SOLDER

SMALL

CONTROL

T

HICK

NYLON

SHOULDER

WASHER

RIGHT

END PLATE

PARTS

I,IOUNTING

Refer

to Detail

44,

for

tfie

following

steps.

(

)

Mount

two

6-32 qreeftruts

on

&re

right

end

plate.

Be

sure ttre

flat

side

ofeachspeednut

is

positioned

as

shown.

Detdil

4A

Mount

the

antenna

bracket

to the

end

plate.

Use

6-32

x 1/4"binder

head

screws,

#6

lock_

washers,

and

6-32

nuts.

Mount

the

2-screw

terminal

strip to

the

antenna

bracket.

Position

it

as

shown.

Use

6-32

x

1/4"

binder

head

screws.

#6

lock_

washers,

and

6-32

nuts.

()

()

(

)Mc

bri

thi

slr

sol

lar

(

)Mc

an(

pol

()Mc

#6

Set

thr

LEFT E

Refer

(

)Mo

RIGHT

END PLATE

6

-32X1/4'

B

IN

OER

/^(t\

v

i

VorurEN*e

BRAC

KET

TERMINAL

STRIP

6-32xt/4

BTNDER

HEAD

SCREW

@EE@l

Pagell

TROL

NUT

CONTROL

NUT

LEFT

ENO PLATE

LARGE

CONTROL

LOCKWASHER

VOLUME

CONTFIOL

Detqil

48

EAFIPHONE

,O.**ffi

TONE

CONTROL

(

)

Mount

the

antenna

brtrshing

to

the

antenna

bracket.

Use the

thicknylon

shoulder

washer,

thin

nylon

shoulder

washer,

solder

lug, and'

small

control

nut.

position

and

ben-d the

solder

lug as

shown.

Tighten

securely

with a

Iarge

screwdriver.

(

)

Mount

the

AFC

switch

with

#4 lockwashers

and

4-40

nuts.

Be

sure the

switch

lugs are

positioned

as

shown.

See

pictorial

4.

(

)

Mount

the

preassembled

FMtuningunitwith

#6 lockwashers

and

6-82

x

B/16n

screws.

Set

the

right

end

plate

aside temporarily.

LEFT

END PLATE

PARTS

MOUNTING

Refer

to Detail

48

for the

following

parts.

(

)

Mount

two

6-32

speednuts

on

the

left end

plate.

Be

sure the

flat

side

ofeachspeednut

is

positioned

as

shown.

(

)

Mount

the

Volume

control

(#19-g1)

with

a

large

control

lockwasher

and

large

control

nut.

Position

th€

lugs

as

shown.

(

)

Mount

the

Tone

control

(#10-1gg)

with

a

small

control

lockwasher

and

small

control

nut.

Position

the

lugs

as

shown.

(

)

Mount

the

earphone

jack

with

a

small

con-

trol

loekwasher

and

small

control

nur.

Position

the

lugs as

shown.

Set the

left

end

plate

aside temporarily.

CIRCUIT

BOARD

MOUNTING

Page

12

Refer

to

Detail

4C

for the

following

steps.

(

)

Prethread

the

endholes

ofthetopahdbottom

circuit

board

brackets

with

a-O-gZ

xg/g,,

self-tapping

screw.

(

)

Mount

the

eircuit

board

to

the

tqp

and

bottom

brackets.

Use

B-49

x

L/4,,

screws.

#3

lock_

washers,

and

B-4g

nuts.

Do

not tighten

the

serews.

(

)

Re^ferring

to Detail

4D,

mount

the

right

and

left

endplates

to the

top

and

bottorn

brickets.

Use

6-32

x

3/16"

screws.

position

the

screws

to

the

rear

(away

from

the

flange)

of

the

slotted

holes

in the

end

plates

ind

tighten.

Now

tighten

the

sereu/sthatholdthe

circuit

board

to

the

top

and

bottom

brackets.

WIRING

CIRGUIT

BOARD

TO

END

PLATES

Refer

to Pictorial

4

(fotd_out

trom

nage

tO)

for

the

following

steps.

Conhect

the

free

endg

of the

wires

comins from

the

circuit

board

to

end

plate

terminils

as

directed

in the

folloWlng

steps:

(

)

Connect

a

.05

pfd

digc

ceramic

capacitor

from

lug

4

(S-2)

to

lug

1

(S-2)-

of

the

Volume

control.

FROM

CIRCUIT

BOARD

POINT

(

)

eart+

(

)

TONE-2

(

)

vol,-l

(

)

vol,_z

(

)

roNE-l'

(

)

roNE-3

(

)

vor,-s

(

)

Arc-2

(

)tr-

(

)rr+

TO

lug

4

of

Volume

eontrol

(NS).

Itig

2

of Tone

control

(S-1).

lug

1

of Volume

control

(NS).

lug

2

of Volurne

control

(S.1).

lug

1 of

Tone

control

(S-1).

lug

3

of Tone

control

(S-1).

lug

3

of

Volume

control

(S_l).

lug

2

of AFC

switch

(NS).

IF-

of

FM

tuning

unit

(S-1).

IF+

of

FM

tuning

unit

(S-1).

3-46

x thil

scREw

Detoll

4c

i

1

l

I

6-32x

3,/t6rscREW

COMPONENT

SI

DE

{

(

)

at

the

free

end

of

the

shieldedcablecoming

from

the

circuit

board,

connect

the

inner

conductor

to

AGC (S-f)

anO

the

shield

to

GND

(S-1)

of the

FM

tuning

unit.

Grip

the

inner

conductor

and

shield

between

the

insulation

and

the

solder

connection

with

long-nose

pliers

to

prevent

heat

damage

to

the

insulation.

(

)

Connect

the

free

lead

of

choke

RFC-1

to

AFC-1

of the

FM

tuning

unit

(NS).

Use

sleeving.

(

)

Connect

a

Bil

wire

from

AFC_2

on

the

FM

tuning

unit (S-f

)

to

lug

2

of ttre

AfC

s*ii"r,

(s-2).

(

)

Connect

a

3-L/4,,

wire

from

AFC_1

of the

rM

luqing

unit

(S-2)

to

lug

1

of the

AFC

switch

(S-1).

NOJ|

: Where

a

wire

goes

through

a

connection

ancl

men

goes

to

another

point,

as

in

the

next

step,

it

will

count

as

two

wires

inthe

solder

in_

.i15t1ctio1q

(S-2),

one

entering

and

one-leaving

me

connection.

(

)

Connect

one end

of a

Z-g/4,,wire

to ANT_I

ot$9

r{i

tuning

unit

(S_1).Strip

!/2,,o!

in_

sulation

from

the

other

end

ot tiis

wireand

pass

the

wire

through

the

solder

luE

at ihe

antenna

bushing (s_2)

to AltT_l

of

the

Z_

screw

terminal

strip (S_1).

)

Connect

a

3-L/4,,

wire

from

ANT-2

of the

2-screw

terminal

strip

(S-1)

to

aNT_?oi

the

FM

tuning

unit

(S-i).

)

Place

a

2"

length

of

sleeving

on the

plus

(+)

lead

of thJ

1000

pfd

tub-ular

eteciro_

lytic

capacitor

(#2b-111).

Bend

ttris-feaa

down

against

the

side

of the

capacitor

as

shown.

)

Mount

the

capacitor

to

the

circuit

board

by

placing

the

lead

from

the

negative

;nJ

into

the

f )

hole

of

the

circuit

board.

place

the

plus

(+)

lead

into

the

(+)

hole

ot

tt

e

ci"_

cuit

board.

Solder

both

leads

to

t}e

circuit

board

and

clip

off

the

excess

wire.

/

\N

t

@\

ql

T

Pagel4

[@EEF

TRANSISTOR

IOCATION

CHART

LOCATION

KIT

A

KTT

B

KTT C

KIT

D

Q?

Q8

Q9

Q10

RED

,N

BROWN

VIOLET

VIOLET

oRAlrGE

nrfr.

BLUE

.

BLUE

GREEN
GREEN

YELLOW

ORANGE

YELLOW
YELLOW

(

)

Remove

1/4" of

insulationfromeachendof

a

9"

length

of stranded

red

wire.

Twist

the

separate

strands

together

tightly

at

each

end

of

the wire.

Then apply

a small

amount

of

solder

to each

end

to hold

the strands

to-

gether.

(

)

Connect one

end of

this 9"

red

wire

to

lug

5

of

the

Volume control

(S-1).

The other

end

will

be connected

later.

(

)

Refer

to the

Transistor

Location

Chart

and

find

the

column

which

corresponds

to

the

transistor

bag

marking

(A

through

D)

fur-

nished

in

your

kit.

Mark out

the other

columns.

The

colors

listed

in

the

proper

column

should

correspond

to

the color

dots on

the

transistors.

NOTE:

Pay

particularly

close

attention

to

tran-

sistor

installation

and conect

positioning.

(

)

Referring

to Detail

4E, cut

the leads

of

the

four 2N12?4

transistors

to 3/16"

and

install

tfiem

in

the

proper

sockets,

accord-

ing

to the

Transistor

Location

Chart-

(

)

Referring

to Detail

4F,

cut

the

leads

of

the

three

2Ni?4?

transistors

to

3/1 6"

and

install

them

in sockets

Q4,

Q5,

and

Q6'

FINAL

WIRING

Refer

to

Pictorial 5

for

the following

steps.

(

)

Cut both

leads

of

the 10

pfd tubular

elec-

trolytic capacitor

to 1f2".

Connect

the

plus

(+)

lead

to

the

(+)

marked

holeandthe

other

lead

to the

(-)

marked

hole

on

the

foil

side

of

the circuit

board.

Solder

both

con-

nections.

Cut off

the

positive lead

on

the

other side

of

the board.

)

Connect

a 2-lf2"

wirefrom

PHONE-1 ofthe

circuit

board

(S-1)

to lug

1 of

the earphone

jack

(S-1).

)

Connect

a LO-l/2"

wire

from

PHONE-2

of

the circuit

board

(S-1)

to lug

2 of

the

ear-

phone

jack (S-1).

)

Locate

the speaker

and cormect

a 9"

wlre

from

lug 3 of

the earphone

jack (S-1)

to lug

1

of

the speaker

(S-1).

)

Connect

a

?"

wire from

SPKR

onthecircuit

board

(S-1)

to lug

2 of

ttre speaker

(S-1)'

EARPHONE

PICTORIAL

5

I@EEEEEI

n"*"tu

Y\

&

6-32 ruur9

I

BATTERY

HOLDER E

Detqil

64

Refer

to Detail

6^4' for the

following

steps.

(

)

Locate

both

battery

holder

ends,

both bat-

tery

springs, and the

battery contactor.

(

)

Install

a

6-32 x

lf4,'

phillips

head screw,

a

spade lug, and

a 6-32 nut

at

plus

(+)

on either

battery holder

end.

(

)

Mount

a battery

spring

in the hole at

minus

(-).

Use a

6-32 xl/4"

phillips

head

screw,

a spade

lug, and a

6-32

nut.

Refer

to Detail

68 for the

following

steps.

(

)

Position

the

red

wire,

coming from tlre

Volume

control,

through

slot

A to the

plus

(+)

spade lug

(S-1).

Clip

off

the excess

wire

close

to the

spade lug.

(

)

Position

the

black v\rire,

coming

from the

circuit

board, through

slot

B to the minus

(-)

spade lug

(S-1).

Clip

off

the

excesswire

close

to the

spade lug.

(

)

Referring

to

Detail

6C, mount

the

battery

'contaetor

and

spring

on

the

remaining bat-

tery

holder

end. Use a

6-32 x l/4"

phillips

head

screw, and

a 6-32 nut

in

the hole at

minus

(-).

PLUS

(,

Detqil

68

o-rz

Hur@

I

BA

ITERY

HOLDER

ENO

BA

TTERY

CONTACTOR

I

I

r

6-32x1/4"

PHILLIPS

HEAD

SCREIY

I

&

Detqil 6c

,ooo. ,-rS*

(*)

"lJ.li:'9

,idlii'r;.'"9

,,:.

L,

""*"tu

@EIEGBI

PLUS

(+)

END

BATTERY

LABEL

PICTORIAL

6

Refer

to Pictorial

6 for

the

following steps.

(

)

Remove

the

paper

backing

from

one of

the

1"

x

1't x1/4"

sponge rubberpads.

Press

the

sticky

side

of

the

pad

firmly againsttheleft

end

plate

at the

location shown in

Pictorial

6.

(

)

Remove

the

paper

backingfromanother 1"x

L" x

l/4" sponge rubber

pad.

Press the

sticky

side of

this

pad

firmly

on

top

of

the

pad

just

installed.

(

)

Cut the

remaining sponge rubber

padintwo,

to make

two

l" x l/2"

x

1/4"

pads.

(

)

As

before,

press

these two 1"

xL/z"x!/4"

sponge rubber

pads,

one on

top

oftheother,

at the

location shown

in the

Pictorial.

l"t1/2"x1/4"

SPONGE

RUBBER

PADS

()

Install

the

six batteries in the

battery

holder.

Position

the

positive

(+)

endsofthebatteries

as

shown

on

the

battery label.

Push

battery

end

D

(the

one

with

battery con-

tactor)

onto either

end

of

the

batteryholder

until

it snaps into

place.

Position the

plus

(+)

end

as

shown.

Install

battery

end C

on

the

battery

hold-

er;

position

the

plus (+)

end as shown.

()

()

(

)

Place

the

battery holder

in the

battery

compartment as it is shown

in

Pictorial

7A.

Be

careful not to damage theearphonejack.

This

completes the wiring

of

your

Portable FM

Radio.

Check

all wiring for anypossible errors,

and make

sure

that all

connections

are soldered,

except the three

holes near transistor socket

Q8.

These

holes

are

provided

for analternate output

to

a hi-fi

system as e:<plained in the Operation

section

of

the

manual.

LEFT

ND

PLATE

e

f

i'iiro*i

.v.it

.

JAcK-

l

"

x l

" r l

/

4"

SPONGE

RUBBER

PADS

()

()
()

Turn

the Volume

control

fully

counterclock-

wise until

the switch on

the rear

of

the

control snaps into

the

Off

position.

Locate tlte

battery holder

and

batterylabel.

Remove

the

paper

backing from

the

battery

label. Stick the

label

on

the

side of

the bat-

tery

holder as shown.

d

il

_t

t

I

;

i

I

i

I

@@l

Pagel?

AEND

ANTENNA

TO

ALIGN

WITH

CORNER

OF

€ND PLATE

TUNING

KNOB

FINAL

ASSEMBLY

Refer

to Pictorial

?A

for

the

following

steps.

(

)

Make

sure

the

Volume

control

is

still

fullv

counterclockwise

and

push

the

Volumeknob

onto the

control

shaft.

(

)

Start

a

4-40

x

L/8,,

setscrew

irnto

a small

tapered

lsrob.

Mount

the

knob

on

tlte

Tone

control

shaft and

tighten

the

setscrew

with

the allen

wrench.

Refer

to Pictorial

?B

for the

following

steps.

(

)

Sllde

the

s$'itch

lever

onto

ttre tuning

shaft'

-so

the

notch

will

engage

the AFC

s-witch.

(

)

Turn

the

FMtuningshaftfullycountercloek_

wise. Positlon

the

large

Tuning

lanob

on

the

large

Tuning

shaft

so that

the dash

(_)

mark

near

il88rr

is

straight

up, then

tighten

the

setscrew.

(

)

nrsn the

small

tuning

linob

onto the

small

Tuning

shaft.

(

)

Staft

a

4-40

xrl/8,,

setscrew

in the

tapered

lcrob.

Mount

the.knob

on

the

switch lever

and

tighten

the

setscrew.

PICTORIAL

78

(

)

Instalt

the

collapsible

antenna

and

extend

it

t9

its

full

length.

To

insure proper

fit

in

the

case,

move

lhe

antenna

foiward

(bend-

ing

the

antenna

bracket)

until

the

antenna

lines

up with

the

corner

of the

end

ptate

as

shown.

The

antenna

should

remain par_

allel

to

the

side

of the

end

plate.

NOTE:

Ttre

blue

and

white

identtfication

label

shows

the

Model

Number

and

production

Series

Number

of

your

kit.

Refer

to

ftese

numbers

ln

any

communications

wtth the

Heath

Company;

this

assures

you

that you

will receive

ttre

moit

complete

and

up-to-date

information

in

return.

(

)

Instatt

the

identificatton

label

in thefollow-

ing

manner:

1.

Select

a

location

for the

label

where

it

can

easily

be

seen when

needed,

but

nrill

not

show

when

the

unit

is

in

oper_

ation.

This

locationmight

be onthe

rear

panel

or the

top

of

the

chassis.

or

on

the

rear

or bottom

of

the

cabinet.

2.

Carefully peel

avay

the

backing paper.

Then

press

the

label

into

poiitton.

PICTORIAL

7A

:;-

NOTE:

An Alignment

section

is

provided, bttt

it

should

not normally

be needed

since

all

adjust-

able

parts

of

this

Radio

are eompletely

pre-

afignet

for

optlmum

receiver

performance,.

p

not

attempt

to

align

this

Radio

unless

you

ha-ve

ffiE necesiary

equipment

and

are enperiencedin

FM alignment

procedures,

re

INITIAL

TiST

AND

ADJUSTMENT

Rotate

the

Volume control

cloclrwlse

util

it

clicks

to

turn'on

the

Radio.

A hisstng

noiee

should be

heard

from

the speaker

with

furtler

increase

in

the

Volume setting. U

no

noige

ls

heard

from

the speaker,

refer

to

the In

Cage Of

Difficutty

section

of

the manual

Q(

DISCONNECT

:*4'*

'*vscE'7

Flsure

t

^qQ'o'

"Bu,f

o''1

i,:

T4

Jrb

'

trLi

o1f{*

I t.:

il E *-Ou

ro

!--

;-i ee.l"

o

-

C-O^ rr.arrd

5^'r-

o)

ll

--o

-"

[rJf.

'lr

-^

--,--,----------

ol l l

l" I tq- l4l

Llo

I

ULra

O l.: n o

*Ai

=

t*"q"C

S-sq.OqzfilO

-=€

n{-

'

P"g;

E:i

u.oE:3'

o

d)o 5

r\a

oooo

FRoNr

a

END

{h 6)

e

osc

TRIMMER

ao

a#Dft

[@EEEEE|

Pagele

Turn

the

Tuning

control

until

a

local

FMstation

is

heard

from

the

speaker.

Adjust

the

Tone

control

for

the

tone

quality

de_

sired.

If

the

sound

is distorted,

the

secondary

of

the

ratio

detector

transformer

Tb

should

be

adjust_

ed

as

follows:

1.

Tune

in

a

ryg4J<

station

carefully

for

the

loudest,

clealist

sound,

wit}r

AF"C

turned

4.

OFF.

Insert

the

short

end

of

the

alignment

tool

supplied

with

the

Radio

into

the

top

slug

of

ratio

deteetor

transformer

Tb.

Refei

to

Figure

1.

fljust

the

top

slug

slowly,

first

in

one

direction

and

then

in the

other

direction

for

the

loudest,

clearest

sound.

CAUTION:

Do

not

turn

tire

slug

more

tfran

i/TTGilE

either

direction.

It

may

be

necessarv

to

carefully

retune

the

station

and

repeat

ihis

adjustment.

R".*.9rr9

the

alignment

tool

carefully

so as

to

not

disturb

the

setting

of the

slug.

COMPLETE

ALIGNMENT

PROCEDURE

USING A swEEP

GENERATOR,

MARKER

GENERATOR,

AND

oscllloscopE

Tuning

Control

-

off station position

Make

sure the

sweep

generator

output

signal

Volume

Control

-

full

counterclockwise

(switch

i"

i;;

;;;gh-i-o p""rr"nitimitinginthelF

stage.

,

3.

AFC

Switch

-

OFF

NOTE:

Refer

to

Figure

1

for

the

locationof

test

and

alignment

points.

Cunnect

I

Swaep

generator

sweep generator

I

mrrker generaror

s;;';;;'

I

ror

anproximare

b;ndwiclth

I

resPonse

Disconnect

positive (+)

lead

of C116

from the

circuit board

Through.0l gfd

capacitor

to

point

D

Top and

bottom

slugs

of

T4

Through.0l pfd

capacrtor

to

point

F

Top

md

bottom

slugs

of T3

Through

100

Ke

registor

to

Tp

on

front

end

Top

ud

bottom

slugs

of

T2

Through

100

KO

resistor

to TP

on front

end

-4

6-32x3/8"

SELF-

TAPPING

SCREW

Refer

to

Detail

8A for the

following steps.

i )

Remove

the

antenna,

all the

knobs ex-

cept

ttte

one from the

switch

lever,

and

remove

the

srvitch lever from the Radio.

(

)

Mount

the

speaker

on

the threaded

spacers

with

6-32 x 3/8"

screws.

Position

the

speaker

and its wires

as shown.

(

)

Place

a

soft

cloth under

ttre

cabinet front.

Mount

the

end

plates

to the

cabinet front

with

four

6-32

x

3/8" self-tapping

screws.

| )

Loosen the

five

screws

that

hold

the end

plate

to the

top and bottom circuit

board

brackets,

and

push

the

circuit board

down

so the

speaker

is tight

against the

cabinet

front. Tighten

the

five

screws

in

the

end

plates.

Refer

to Pictorial

8 for

the

following steps.

(

)

Remove

the

two

screws that

holdthecircuit

board to the

top

threaded

spacers.

(

)

Carefully

position

the

leather

case overthe

Radio

as

shown. Be

sure all

wires

are

pushed

clear

of

the

areacoveredbvthe

leatlercase

brackets.

S--

{

U(\

Detqil 8A

CABINET

ASSEMBLY

CAAINET

page

21

(

)

Remove

the

adhesive

backing

from

the

nameplate

and press

it

firmly

iirto

the

oval

of the

cabinet

front.

This

completes

assembiy

of

your

portable

FM

Radio.

(

)

InstaU

6-82

x

B/g"

screws

through

the

two

top

brackets,

6-82

x

3/9"

screws-inttresiee

brackets,.and

6-82

x

l/Z,,screws

and

flat

washers

tlirough

the

bottom

holee

of the

leather

case.

(

)

Replace

the-

switch

lever,

the

knobs.

andthe

N'

M

4Vt

PICTORIAL

8

C€

3

nr*"r,

f@EP-l

OPERATION

i

1

:1

I

.l

I

Operation

of

the

FM

Radio

is simple and

conven-

tional.

Turn

on

the Radio,

move

the

AFC

switch

to

the

OFF

position

and

select the desired

station

with the

large

Tuning

lmob.

Rotate the

small

Tuning

knob

back

and forth until the

selected

station

sounds the

loudest

and the

clearest,

then

move

the AFC

switch to the

ON

position.

Adjust

the Volume

and Tone

controlsforthe

soundlevel

and tone

quality

desired.

If the dial

indication does

not agree with the

station

frequency

listing

of

your

local news-

paper,

loosen

the

setscrew

of

the

large Tuning

lctob and align

the

proper

dial

number

with the

locating

button

on

the

cabinet above the Tuning

lorob, Retighten

ttre

setscrew.

By

plugging

an

earphone into the Earptrone

jack,

the

speaker

of

the

Radio will automatically

be

disconnected,

changing the Radio

into

apersohal

portable.

The Earphone

jack

canalsobeusedfor

connecting

the Radio

to the tuner

or

auxiliary

input

of a hi-fi

system.

No

pilot

light

is

provided

to indicate when

the

Radio

is turned

on because the

light would

con-

sume about

10

times

the

power

required

by

the

Radio

itself,

thus

severely

reducing

battery life.

Make

it

a habit

to turn

off

the Radio

after

use

to

obtain maximum

battery

economy.

Reception

in

automobiles

and trains

is

possible

in most

locations.

It may

be necessary to

place

the

Radio

near

a window

of

the

vehicle for

best

reception

because

the metal

vehicle body will

act as a

shield against

the

reception

of

radio

signals.

The automobile

radio anterma

can be connected

to

either

screw

of

the

external antennaterminal

strip

of

the FM

Radio.

You will

probably

notice

some distortion

of

the

sound

at

maximum

volume. This

is normal

and

represents

the

reserve

of

power

that

provides

good

reception

even when

the

batteries

run

down

considerably.

Signs of weak batteries

are

low volume,

excessive

distortion, and fail-

ure to

operate

at some

section

of

the dial.

ALWAYS

REMOIV'E EXHAUSTED

BATTERIES

IMMEDIATELY.

THE

OLD BATTERIES

MAY

SWELL

AND

MAKE

REMOVALDIFFICULT,

OR

MAY

LEAK

CHEMICAL COMPOUNDS

TTIAT

WILL

CAUSE CORROSION. DO NOT

STORE

THE

RADIO FOR

EXTENDED PERIODS

WITHOUT

REMOVING

THE

BATTERIES.

The

cabinet should withstand all normal handl-

ing. It may

be

cleaned

with a damp

cloth

and

mild

soap when necessary.

DO

NOT

use sol-

vents,

cleaning

fluids,

or

abrasives to

clean

the

cabinet.

ALTERNATE

HI.FI

OUTPUT

Due

to

some

loss

of

high

audio frequencies

in

the

driver

and

output stages

of the Radio,

greater

frequency

response for

operation

through

a hi-fi

system

can be

obtained by

making

the

following

circuit

addition

to the Radio.

The

parts

necessary

for this

circuit addition

should

be

obtained locally.

(

)

Referring to

Figure

2, install a 10

pfd

10

V electrolytic

capacitor. Be sure to

connect the

positive (+)

lead

of

the

ca-

pacitor

as

shown.

.[-___l.

F igure

2

/-t-\

qc

(

it9)

c--^-''o

roNE

3

-;

e(

)6\'o,^ro

-

^Y\2ol

(.

OB\

Y l+/-\-^

r

.

(=7'e

Page

28

(

)

Add

a

#6

solder

lug

under

the

cabiner

mounting

screw.

(

)

hepare

the

desired

length

of

shielded

cable

and

solder

the

inner

coiductor

in

tfr"

irrii_

cated

hole

of the

circuit

board.

Sofa""

in"

shield

to

the

solder

lug.

(

)

Corurect

the

free

end

of the

shielded

cable

to

a

high

impedance

input

(100

Kfl

""t

igh""l

IN

CASE

OF

NOTE:

Refer

to

the

Kit

Builders

Gutde

for

Service

and Warranty

information.

UNIT

FAILS

TO

OPERATE

l.

Recheck

the

wiring.

Trace

each

lead

in

colored pencil

on the

pictorlal

as

it

ig

checked.

It

is

frequenfly

helpful

to

have

a

friend

check

your

work.

Someone

whoisnot

famlliar

vith

ttre

unlt

may

notice

somethlng

conslstently

overlooked

by the

constructor.

It

ts

lnteregting

to

note

thataboutg0%of

the

kits

that

are

returned

for

repair,

do

not

fimction properly

due

to

poor-connections

and

-soldering.

Therefore,

many

trorbles

9an

be

eliminated

by

reheittng

all

connec-

tlons

to

malce

sure

that

they

are

soldered

as

descrlbed

in tlre

Solderlng

gecflon

of

the

Ktt

Bullders

Guide.

Check the

values

of the

parts.

Be

sure

that the

proper

part

has

been

wired

lnto

the

clrcult,

as

shou,n

in

the

pictortal

diagrams

and

as

called

out tn the

wiring

lngtructlons.

of

your

hi-fi

system.

I%9,

It

will

benecessarytomakeupa

,dummy

l.oad'

to protect

the

output

t"r""io"'-"".

irj

,o

disconnect

.the

speaker

of the

n"ai"-rii",

ii

i"

conne,cted

to

a

hi-fi

system.

fnis

can

Le

ac_

complished

by

connecting

a-4

o

1n

iiti

,"_

sistor

b-etween

the

lugs

of a

miniatur"

""rofro""

pru-9.

flug

this

dummy

load

into

ttre

Earphone

jack

of the

Radio.

DIFFICULTY

4.

Check

for

btts

of solder,

wlre

ends

orother

foreign

matter

vhich

niay

Ue

foagea

in

tt

e

wtrlng.

5.

If,

after

careful

checks,

ttte

trouble

is

sflU

not

located

and

a

voltmeter

is

available,

chec!

voltage

readings

agairrst

Urose

;how,

on

ttte

Schematic

Diagram.

NOTE:

All

voltage

readings

were

laken

with

an

1l

megohm

input

vacqum

tube

voltmeter.

Volt_

ages

may

vary

as

much

as

10%.

2.

3.

6.

Check

transistors

wlth

a

transietor

tester

or

by

substitution

of tranststors

of the

same

t1ryes,

known

to

be

good.

:-

'--

7.

A

revlew

of the

Clrcult

Descrlption

wfll

prove

helpful

tn

indtcattng

wher!

to

bok

for

trouble.

_1.

.1

I

i
I

i

I

TROUBLESHOOTING

CHART

CONDITIONS POSSIBLE

CAUSE

Radio

completely dead. 1.

Faulty

batteries.

2. Off-On

switch inoperative.

3.

Transistors

installed

wrong.

4.

Faulty

transistors

Q?, eg,

e9, e1O.

5. Open winding

in T3,

T4, T5.

Hiss

in speaker, but

no stations received.

1.

Faulty

transistor

Ql,

Q2,

Q3.

2.

Improper

alignment.

3. Open

winding

ih T3, T4, T5.

4.

Faulty

diode D2.

5. Open

capacitors C119, C120.

Radio

r?motorboats"

(pulsating

sound output).

1. Open capacitors

C125,

C126.

Ortput distorted.

1.

Batteries

weak.

2. Faulty transformer

T5,

3.

Improper

alignment.

4. Volume

turned

up

too

high.

5.

Electrolytic

capacitor

polarity

reversed.

6.

Faulty

transistor

Q9

or

Q10.

U after making

the

above checks, theRadiodoes

not

perform properly,

the

simple

point-to-point

test described

below

can be used to locate

the

stage not functioning.

Wtth

the

speaker

removed from the

chassis,

turn the Radio

on

and turn the Volume control

to

the full

clockwise

posltion.

Touch the

collector

lead

of

transistor

Q8

on

the

component

side

of

tlte

cbcuit board

with the

metal

blade

of

a

screwdriver.

You

must touch the

blade

of

the

screwdriver

with

your

finger.

(There

is no

shock hazard

in

the

Radio because

of

the

low

battery

voltage.)

A weak

click

should

be heard. If not, it would

indicate that

transistor

Q9

or

Q10

or

I

com-

ponent

in

one

or

both

of these stages is

faulty.

If

everythtng

checks

out

to

this

polnt,

you

can

then

check

the

base

d

Q?,

collector

of

Q6,

Q5, Q4,

and t}te

antenna corurection.

With

a

click at the

collector but not at

the

base

of any

one

transistor

(except

Q?,

at the base),

more

than

likely the

transistor

is faulty. How-

ever,

lf a

click is

present

at the

base

of one

transistor

but

not

present

at

the

collector

(emitter

of

Q?)

of

the

next

one, as

you

move

forward

in the

circuit toward the

antenna,

you

should

suspect that a

component betweenthetvo

transistors

is

faulty. lhe

gain

in

stages

Q9

and

Q10

being

so small makes it almost

imposstble

to

hear

any

click wtren

touching

either

their

base

or

collector leads.

After

locatfurg the

stage

that

does

not frrnctlon

properly,

carefully

check all

components

to see

that

they

are in the

proper

location,

check

solder

connections,

and

replace transistors

if neces-

sary.

This_

X-Ray

view

of the

circuit

board

is

pro_

vided

to

aid

in

troubleshooting.

-v-'5

'p

vr'

INTRODUCTION

TO

TRANSTSTORS

Trangistors

have

been

one

ofthemostimportant

developments

in

the

fiefd

or

"r"ct"on-lc"liiir,ougn

they

have

been

availablu

"o-*""-.

i.iiv

l"i

",iry

"

fe-w

years,

'!ey

have

alreadyfound

rpiri""tio,

in

every

branch

of the

art.

tirev

can-is"ur""'tn"

duties

of

vacuum

tufey

in

**V

"ppfi""iior",

and_

thev

are

employeo

in

such

a

;dilil;t;hi"

Radio.

Llat*o": _possess

many

advantages

over

lyl-git

Probabty

the

one

most

apparent

is

their

eltr.emelr

small

size,

ma*ini-

p-ossiiie*

itr"

miniaturization

of

equii*ent

ir,'*ililtii"i,

""u

ys_ed..

CIher

aovantages

"r"o

,ri."

li"

.JJ

",

trans

istors

de

s

ir

able

-as

will

be

"r.pl

"inl

jin"tr,

"

following

paragraph.

Becaugg

9f

their

small

size,

transistors

possess

very

little

mass

or

inertia.

a"

"

"""irlii"u

a1e

1ot

subject

to

the

shoek,

vibration

and

micro_

phontc

.faults

of

tubes.

rrinsi;a;;;;';;;.r_

tain

a

heater

or

filament,

-re;uir;;;

;;;rp

311 : T

"j-"

-

no

power

*r,

icri

"

"',.l"

iu"lti

"llti

ine

to

useful

audio

output.

gecause

no;;;il;"r_

erated

within

the

cabinet,

fonsu"

iif"

;;

i"-"*-

pected

.from

other

componeits

suuiecl

io

a"-

terioration

from

heat.

id;il;;f;;;"

.,,

very

low potential

or

vottage,

measured

involts

11ther

than

tens

or

rrunorZds-

"il"ir:"ri

J_i'i"tr,

tubes.

This

makes

battery

operation

very

feas-

ible

and

eliminates

comptlteiy

ue

"L""iiirl"o

l1T3*- ry:t lube

e

qurpm"ri

r"

_"}'Jt"""

"Tiru

an

extremely

lone

life

expectancy.

iil;;L"

life

of

transistorl

has,not

yet

lieen

aeiirrit"fy

lltS_rl-"-l"d,"implyduetoladk"iii;;;;;;;r"

at

repres

entative

f igures.

rransisG;s

r,""1

#"n

_T _"o$hyoys _

operition

i."

v""""

-*itirJui

ffu_

ure.

Mo-st

failures

are

caused

uy

i_p"lp""

i""

rather

than

by

deficiencies

in

tft

b#il.cl-e"il.

X-RAY

VIEW

(RESrsroRS)

(cAPACtroRs)

5

I
:

1

t

n"u"u

@EiFr

As with

any

good

thing, there

are also limita-

tions to the

capabilities

of

transistors. Pri-

marily,

these

limitations involve

power

handling

capabilities, high frequency

limitations and

ex-

treme temperature

limitations. None

of

these

limitations

are

approached

in

their

application

in this Radio.

One

precaution

must be

observed,

however. The

battery must

be installed exactly

BA'E

as

instructed

or

damage

to the transistors

may

nECroN

result.

Consider

briefly

the

nature

and

construction

of

transistors.

The

material

used in the

f abricatron

of a transistor

is a

so-called

semi-conductor.

Germanium

and

silicon

are two

basie

materials

in

common

use today. All

the

transistors

in the

Radio

are

of

the

germanium

type

although

silicon

transistors

could

be made

to

perform

satis-

factorily

also.

Stated

simply,

a transistor

con-

sists

of

a

"sandwich"

of various

alloys

of

ger-

manium.

Three

layers

of

the

alloys form

this

sandwich.

A

connecting

lead is

attached to

each

of the

layers and

brought

out for external

c6n-

nections.

It might

be

of interest

to note

here

some of

the

production

problems

connected

with the

making

of a transistor,

The

germanium

must

first be

refined to

an

extremely

high degree

of

purity.

The

rigid

requirements

would

compare to allow-

ing

no more

than

one kernel

of

corn in

several

carloads

of wheat.

The

pure

germanium

is then

"doped"

with

precisely

controlled

amounts of

other elements

to

obtain

the

properalloyneces-

sary for

transistor

action.

More

will be said

about

the

doping

process

later.

The center

layer

or

"meat"

of

the

sandwich may be

only

l/1000 inch

thick. This

layer must

be

pre-

cisely located,

and

a wire attached. The

entire

process

must

be

performed

under

"operating-

room"

clean

c onditions. Any

contamination

of

the

transistor may

be

cause for

failure.

The as-

sembly is

then

hermetically

sealed in

a

pro-

tective

case,

often

with

an inert

compound

to

assist

in

conducting heat away

from the as-

sembly. The drawing

shows a typical transistor

assembly.

As mentioned

before, the

germanium

must be

doped

to

obtain the

characteristics needed for

transistor

action.

Different

materials are used

to

produce

a

"P"

or

arr

I'Nrr

type

germanium.

"P"

type

germanium

means

tltat

the

pure

metal

COLLECTOR

LEAD

ALL

LEADS ARE

SEALED

IN

BASE LEAD

tYltoto.*

HERMETICALLY

GLASS

PROTECTIVE

COVER

HERMETICALLY

SEALED AFTER

ASSEMBLY

GERMANIUM

BAR

has

been modified

so tlat

there

is

an

electron

deficiency

in the

natural

crystal

structure.

often

referred

to

as

a

"hole."

"N"

tytr)e

germanium

means

tiat

an

electron

excess

is

created

in the

natural germanium

crystal,

Transistors

are

produced

in

both

NPN

and

pNp

configurations,

the

letters

indicating

ttre

type

of

germanium

in

each

of the

layers.

The

schematic

representa-

tion

for the

transistor

identifies

the

type

as

shown

in

the two

diagrams.

The

middle

layer

of

the

sandwich

is

called the

base.

One

outside

layer

is

called the

emitter

and

the

other

one the

collector,

The

junctions

formed

between

the

emitter

andbase

andbetween

the

collector

and

base

have

a

characteristic

similar

to

that

of a diode

rectifier,

in that

the

junction

will

conduct

current

much

more

readily

in

one

direction

than

the

other. When

voltage

is

applied

across

a

junction,

with apositive

voltage

applied

to

the

"P"

t14pe

region

and

negative

voltage

to

the

"N"

type

region,

a

current

con-

sisting

of

two

components

will

flow. Electrons

will

flow

from

the

"N"

region

across the

junction

to

the

"P"

region

and holes

will

flow

or

mi-

grate

from

the

"P"

region

across

the

jurction

to tlle

"N'

region.

If the

polarity

of

the

applied

voltage

is

reversed,

the

electrons

and holes

move

away

from

ttre

junction

and

for

practical

purposes,

no

current

will flow.

The

drawings

illustrate

this

effect.

Page

27

PN

tr

-

f l

._-1--

l-- r

tl

ll

r

1r1-_(

/\

J

AATI€RY

\..1

)

CURRENT

diffuse

across

ttre

base

region

and

appear

as

a

current

in

the

collector

circuit.

Sin""

ttl

"*itt."

bias

is-

usually

a

very

row

voriage (blii,i'rn

tt

"

fo11gd

direction),

ano

tne

"oiLiioi'?i""

i"

relativety

high (being

in

ttre

revirs"-Ji"Jotiont,

the

transistor

is

able

to

proouce

a;;;;

g"_.

This

can

readily

be

seen

when

you

consider

that

power

is

the

product

ot

"onrgJ;;o"cirr""r,t.

Because

the

current

flow

is

across

a

junction

of

very

small

area,

ttr"

p"*""'t*;rr#;

"._

pabilities

of a

traniistor

are

-ri*iiill"

m

heating

caused

bv

the

""""*in"*irrJinio,rgn

the

jwrction

resisiance.

RADIO

TERMS

AIVIPERE

-

The

unit

of

measurement

of

current

flow.

The

number

of

etectrons

p*""iig?prrr,

in

one

second.

gi+U+. -,

A

system

of

conductors

used

to

raclrate

or

intercept

radio

signals

#+9TOI

-

A

comoonent

consistins

of

con_

gucl{rc

plates

separated

by

."

inrui"ii"'e'."._

terial.

Various

materials

and

construction

are

used

in_the

capacitors

in

the

radio.

fi"o""it"O

sitver plates

on

ceram_ic

f",

ur"-;;;;";;:;;r".,

atylin3m

foil

plates

separated

by

a

chemical

oxide.

for

ttre

electrolytic

capacii6r;

;;;;"".

aluminum

separated

6y

ai"^io"-lr,l

li"i.m"

tuning

capacitor.

Capacitors

are

u."O

tl

ou""

AC

while

blocking

DC

ana

arso

to

til-."o"",,i""_

onate"

electrical-

circuits

to

a

desired

fre_

quency.

C,9IL

-

A

component

consisting

of

wire

or

some

other

conductor

wound

in

tur:ns-on-.

"rii"nf"

form.

The

number

or

turns

ana

i,J

"il"llirin",

and

material

used

for

ttre

form

,""

J"#ir"i""a

by

the

application.

Coils

are

"tt",

"""d^

iiti,

capacitors

to

form

"tuned', circuits-

SolDUqq@

-

Any

material

that

permits

easy

passage

of

an

electrical

current.

:C:OTtffIER

or MIXER

-

Circuitry

desisnedro

comour.e-

the

signal

from

the

raOio

stati&r

witfr

an

oscillator

signal

to

produce

"

n"*

"lE"i

"t

a

different

frequency.

Se;

hete;;;;;

In

most

applications,..transistors

have

operating

vouages

applied

so.'that

the

b;;;_

;;;ti5i'

;un"

_

tion

is

"biased',

in

the

forward

"_"."Or"iir,gai_

rection

and

the

base_collecto"

:*"t-io"

i!-ibi."_

ed"

ill

t}te

reverse

or

non_conducting

direction.

when

connected

in

this

-*.;;;;;;?J'ir,""

".,"_

renr

carriers

flowing

in

the

emitte"

"i"".rit

*Uf

GLOSSARY

OF

While

by

no

means

.complete,

this

glossary

should

assist

those

wtro

are

".]t

-r-"iir?ri"*itt

radio

terminology.

The.

Aefiniiions*

appfi

to

af

f

radios

in general

bur

rn

many

cases

refer

to

this

Radio

spe

c

if ic

ally.

furtfrer

intorm"iiori*ry

b.e

obtained

from

texts

available

"t-_o"f"p*fi"

libraries.

!9

-

Alternating

Current.

An

electricalcurrenr

that

reverses

iis

direction

ot

no*-"i-iJgur."

intervals.

House

current

makes

120

reversals

every

second.

Two

reversals

"""

n"a""""f

ro

complete

one

cycle,

hence

60

.V"f-"".-?u"n

l^t*I"

frequ-encies

appe-ar

in

radio

ti""uit"v,

,rp

to

many

millions

of

cycles

p""

"".onJ.-

----'

A!]

-

Audio

Frequency.

Those

frequencies

that

fall

within

the

range

"f

ifr"

-nu*"r""'*'**""r_

l"l"ly

20 to

20,000

cycles

pe"

s"cond.

ne_

m_ember

that

ttre

ear

can

only

hear

mechanical

vibrations

in

th'e

air,

not

electricai;;;;;.".

AGC

I

Automatic

Gain

Control.

Circuitrv

em_

ployed

in

a

receiver

t"

adj;t-A;-;Jr"

*

opposite

proportion

to

the

strength

of ine

-re_

ceived

signal.

Used

to

reduce

"tne

efects

ot

ladlq

sienafs,

or

"blasting',

when

t*i";l;;_"

weak

to

a

strong

signal.

AyP!re

-

A

circuit

designed

to

increase

the

fluL*l

-o"

amplitude

of

weat

signals.

Ideally

ln".gutp,rt

signal

is

an

exact

magnUied

repro_

duction

of the

input

signal.

1-

i

HERMETICALLY
SEALED

AFTER

ASSEMBLY

BAR

IUM

:i

EMITTER

LEAD

I

t

I

I

I

has

been

modified

so that

there

is

an

electron

deficiency

in

the

natural

crystalstructure,

often

referred

to

ag a

"hole." "N"

type

germanium

means

that

an

electron

excess

is

created

in the

natural

germanium

crystal.

Transistors

are

produced

in

both NPN

and

pNp

configurations,

the

letters

indicating

the type

of

germanium

in

each

of

the

layers.

The

schematic

representa-

tion

for the

transistor

identifies

the

type

as

shown

in ttre

two

diagrams.

The

middle

layer

of

the

sandwich

is

called

the

base.

One

outside layer

is

called the

emitter

and

the

other

one

the

collector.

The

jr:nctions

formed

between

the

emitter

andbase

andbetween

the

collector

and

base

have

a

characteristic

similar

to ttrat

of

a diode

rectifier,

in

that the

junction

will

conduct

current

much

more

readily

in

one direction

than

the

other.

When

voltage

is

applied

across

a

junction,

with

apositive

voltage

applied

to

the

I'P'

type

region

and negative

voltage

to

the

I'N'r

t1rye

region,

a

current

con.

sisting

of

two

components

will

flow. Electrons

will

flow

from

the

"N"

region

across

the

jwrction

to the

'rP"

region

and

holes

will

flow

or

mi-

grate

from the

"Prr

region across

the

jturction

to

Ule

rrN'!

region. If

the

polarity

of

the

applied

voltage

is

reversed,

the

electrons

and

holes

move

away

from

ttre

junction

and

for

practical

purposes,

no

cument will

flow.

The drawings

illustrate

this

effect.

"'*"'u

@EE@l

As with

any

good

thing, there are also

timita-

tions to the

capabilities

of

transistors. Pri-

marily,

these

limitations

involve

power

handling

capabilities,

high frequency

limitations and

ex-

treme

temperature

limitations.

None

of

these

limitations

are approached

in

their application

in

tltis Radio,

One

precaution

must be

observed,

however. The

battery must be installed

exactly

BASE

as instructed

or

damage to

the transistors

may

nECioN

result.

Consider

briefly the

nature

and

construction

of

transistors.

The material

used in the fabrication

of a transistor

is

a

so-called

semi-conductor.

Germanium

and

silicon are

two

basic materials

in

common

use today. All

ttre

transistors

in the

Radio

are

of

the

germaniumtype

although

silicon

transistors

could

be made

to

perform

satis-

factorily

also, Stated

simply,

a transistor

con-

sists

of

a

"sandwich"

of various

alloys

of

ger-

manium.

Three

layers

of

the

alloys

form

this

sandwich. A

connecting

lead is

attached to

each

of the

layers

and

brought

out

for

external

c6n-

nections.

It

might

be

of

interest

to

note

here some

of

the

production

problems

connected

with the making

of

a

transistor.

The

germanium

must first

be

refined

to

an

extremely

high degree

of

purity.

The

rigid

requirements

would

compare

to

allow-

ing no

more than

one kernel

of corn in

several

carloads

of wheat. The

pure

germanium

is then

"doped"

with

precisely

controlled amounts

of

other elements

to

obrtain

the

properalloyneces-

sary

for transistor

action.

More will

be said

about the

doping

process

later. The

center

Iayer

or

"meat"

of

the

sandwich may

be

only

t/lloc inch

thick.

This

layer must

be

pre-

cisely located,

and a wire

attached. The

entire

process

must

be

performed

under

"operating-

room"

clean

conditions.

Any

contamination

of

the

transistor

may

be

cause

for failure. The

as-

sembly is then

hermetically

sealed

in a

pro-

tective

case,

often

with an

inert compound to

assist

in

conducting heat away from

the as-

sembly. The

drawing

shows a typical transistor

assembly.

As

mentioned

before, the

germanium

must

be

doped

to

obtain

the

characteristics needed for

transistor

action. Different

materials are

used

to

produce

a

"P"

or arr

"N'

tlpe

germanium.

"P"

t5n)e

germanium

means that the

pure

metal

COLLF.CTOR

LEAD

BASE

LEAD

ALL

LEADS

ARE

SEALED

IN

HERMETICALLY

GLASS

PROTECTIVE

COVER

T'

**""

@ElFl

CURRENT

-

Generally

the

movement

of elec-

trons through

a

conductor. In

vacuum

tubes

electron flow

occurs in the vacuum. Movement

of

"holes"

can

constitute

current

flow

in

tran-

sistors.

DC

-

Direet

Current.

An

electrical current

that flows in

one

direction

only.

RATIO DETECTOR

-

A

circuit

used to extract

the intelligence

or

desired

information from a

FM

radio

signal. Ir the Radio this

intelligence

consists

of

the

speech

or

music transmitted

by

the

radio station.

DIODE

-

A two

element

or

two te:nminal device

capable

of

passing

an electrical

current

in

one

direction

only. Used in

the

ratio detector

cir-

cuit in the Radio.

FREQUENCY

-

Repetition

rate of

analternating

current

or of

the

vibration

of

the loudspeaker

cone.

Measured

in

cycles

per

second.

GROUND

-

An

electrical

connectiontotheearth.

Also

the reference

point

for

signals

and

oper-

ating voltages

in electronic equipment, usually

the

chassis.

HETERODYNE

-

The result

of combining signals

of

different

frequencies

in

order

to

obtain

a signal

of

new

frequency. Either the

sum

or

the

differ-

ence frequency

of

the two is

generally

the desired

resulting frequency.

Also

loxown

as

"beat."

!f

-

Intermediate

Frequency. The

heterodyne

or

beat frequency

produced

by the mixer. Most

of

the

amplification

and selectivity

of

the

radio

signals is accomplished

at this

frequency.

AnIF

of 10.7 mc is

employed

by

this Radio.

INDUCTANCE

-

The

property

of

acoiltooppose

any-chang-e-m the

magnitude

of an electrical

current flowing in

it.

INSULATOR - Any material

thatdoesnotpermit

easy

passage

of

an electrical current.

KC

-

Kilocycle

-

1,000 cycles.

MC

-

Megacyele

-

1,000,000 cycles,

1,000

kilocycles.

MEGOHM

-

1,000,000

ohms.

MICROFARAD

-

A

rmit

of

capacity.

Refers

to

6-eGEEid[-"size"

of

a capacitor, one

mil-

lionth

of a

farad.

OHM

(O)

-

The

unit

of electrical

resistance.

OSCILLATOR

-

Circuitry designed

to

generate

AC

at

some desired

frequency

when

operated

from

a DC

source.

Usually

some circuit

element

or elements

are adjustable

sothat adesiredfre-

quency

may

be obtained.

RF

-

Radio Frequency.

Those

frequencies

em-

ployed

for transmission

of

radio

signals, from

10 kilocycles

to

100,000

megacycles.

RESISTOR

-

A

component designedtoopposethe

flow

of current. The degree

of opposition

or

resistance

is measured

in units

called

"ohms."

Resistors

are

used to reduce

current

orvoltage

to

a desired

value, to

provide

isolation

between

circuits

or

to

provide

a

load across which a

use-

ful

signal

may

be developed. Resistors

used in

this

Radio

are made

of

a

carbon

compound

housed

in an insulating

protective

sleeve,

Wire

leads

sealed

in

each end

provide

electrical

connection

to the

resistance material.

SELECTMTY

-

The abilityof

areceivertosep-

araifi;aio,stations

operating on

adjacent

chan-

nels. In the FM

broadcast

band

these

channels

are

assigned

at 200 kilocycle

intervals, that is 89

mc,

89.2 mc, 89.4 mc,

etc.

[@Fl

n'o'n

SENSITIVIIY

-

A

figure that

e:qtresses

the

sig-

nal strength

required at the

receiver

antenna

to

produce

a

specified amount

of sound fromthe

loudspeaker.

SUPERHETERODYI{E

-

A

radio

circuit

that

heterodynes

or convertg an incoming signal of

any frequency in

its

tuning

range

to a

signal of

constant frequency

before amplification

and de-

tection. This

is accomplished by

combining

the

incoming

signal

with

one from a self-contained

oscillator

that is

automatically

trmed

by

the

gtation

selector. h this Radio

the

oscillator sig-

nal ig always 10.?

megacycles

higher in fre-

quency

than the incoming

signal.

The resultant

signal

therefore

ig 10.? megacycles,

the inter-

mediate frequency.

Amplification

of

the

radio

signals may

then

be accomplished

at a fixed

frequency. This

males it

possible

to design

maximum

efficiency tnto

the IF

amplifiers.

Im-

proved

selectivity and

sensitivity

are

advantages

of

the

superheterodyne circuit.

E!4If.ISFORMER

-

A

component

designedto

cou-

pffiiffior

energy

from

one circuit

to

another. Construction

can

vary

widely depending

on

the

application but

generallyconsists

ofinsu-

lated

coils

of

wire

wound

on

a

common

form.

The form maybeofsheetironforpower or

audic

transformers,

or

powdered

iron

or

air for IF and

RF transformerg. Transformers ai'e employed
for

one or

more

ofseveralreasons;

theyprovide

coupling of signals

while isolating

the DC

oper-

ating voltages

of

the.coupled

circuits;

they

are

capable of

producing

AC

voltage

"step-up"

or

"step-down;"

t}tey may be tuned

to

provide.

se-

lective coupling of signals

ae the case of

the IF

transformers

used,

they

provide

proper

imped-

ance

matching between

coupled

circuits.

The

last

application

can

be compared

to the firnction

of

the transmission

of

your

automobile.

The

transmission

is designed to

provide

the most

efficient match or coupling

between

the source

of

power,

the

engine,

and the load,

the

rear

wheels.

A

good

example of

this application

is

the audio

output

transformer

which

provldes

the

proper

match

or coupling

between

the source of

power

(the

transistors) and

the load

(the

loud-

spealser).

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