Realistic DX-75 User Manual

Ltstlc-

COM

MUN

INSTRUCTIONS

I

OPERATING

SERVICE

AT I ON

C

AND

REC

IV

E

R

E

M(IDEL

RADIO

SHACK

DIVISION

OF

TANDY

DX.I5

CORPORATION

COR,PORATION

#

INTRODUCTION

The Realistic

rvideboth

to

I

-75

DX

Communications Receiver is desig'ned

usual

"long

wave" standard broadcast

the
recei)tion and'short wave' international
tion. Therefore,
ald

travel around

of

radio

waves.

Short wave radr,r signals
nission

becausc

it allows the listener to

the

world

means of

by

arcused forlong

of the way they

are reflectcd back
earth by the ionosplx'rc. Radiation frorn
Ironr thc
above thc carth.
trate t.hcse tonized gascs; rnst.ead,
earth much like a stone skips
watcr.

sut)causes ioniz:ltioll olthe loycrs

wrr,rt

Shott

r-aclio signals rvill not

they

across

the

Variations

in thc reflccting

charactcristics
ionosphere due to sun spots, scasons,
producc periods
is

espccially effective.
cur h regular
ule

the

of

Darts

best times to

of

the world.

the

when

cycles the

skipping

nrany of these

Sincc

listener may

listen for

of short wave signals

sisnals from distant

the

recep-

oceans

broadcast

span

radio waves.

distance

space

trans-

(primarily

oI gascs higlt

pcne-

bounce back

surface

to

of quiet

of

tlre

time of day, etc.,

periods

oc-

develop a sched-

to

Listed

below are

[hat can be heard

sone

on the short wave bands:
Amateur
Mobile

Military
Citizens
lnt.

Short Wave

Standard Time Sigrnls

Thc Realistic DX-75
covcrs the
550 to 1600

tlrree

Utilizing four

perf

tube

cuit is
power
ard of a

model

rule" type
plus

busy

standarcl

KC; and the

bands: 1.6

to 4.4 MC; 4.5 to fl

tubes

o rmance

plus

)
designed to operate
source. A

hot

cabinet,

power

chassis.

the

dial with continuous tuning of
bandspread for
short

wave bands.

of the

(Ham)

Radio

Radio - Telepirone

(CB)

Band

types of

many

(Voice

of America, etc.

(WWV)

GENERAL

is a four band

broadcast

short

AM

frequencies

wave

receiver which

MC;

(one

multipurpose tube affords

rec tif ie

the

r,

105 to l25volt, 60

a

from

supe rhetrodyne c i r

transformer eliminates

Housed in a vinyl clad steel

receiver features

an eight

all four bands,

precise

location

of

signals

broadcasts

in

one band:

frequencies

ll

to 30MC.

five

cycle

the

haz

taple

"slide

inch

on

)

in

-

-

tie

SPECIF'ICATIONS

OPERATION

Ditncnsions
Wcight
Frequency Rangc

Sens itivity

Selectivity

Audio

Power

(net)

Orltput

Input Voltage

Consumption

INSTALLATION

Choice of a location for
several

oI
listencr,
outside

available
ed
be

The

however, an outside

ception
outside

as
signals.

lines, trees, buildings,

its

16 ga.

both the
should

storm

design
American
antenna handbooks

Connect the down
nal on
nal
power

power.

considerations.

lurnitur-c

that the selection

carefully

possible (up

supports

to a

in thc

roon,

and acccss to a

antenna. MarT hours

from a

short wave ll:cciver soitis

made,

antenna for

on
antenna

The

copper covered steel wire

antenna and the down lead. A lightening

be connected
damage.

refer to

the rear of

good

cord into

standard broadcast

antenna

the short

antenna

by glass

Radio Relay League, or to any

earth ground

wave bands. As a general

should

to I00

ft.)

should be mounted

to

For additional

'A.

R. R.

currently

lead from the

the receiver

standard

a

6-5/16 x

5

1

550

3.5prv
noisc

6 db

60 db

I

.5 warrs

105 to 125 volts, 60

14-I/4 x Lt)-17/32

pounds

to 1600

at

KC

20 MC

ratio with 30/s

14.5

dorvn,

I 25

dorvn,

­(6

1.6

KC;

KC

to

db

signal-to-

mocl .

cps

30

MC

)

35 watts

tlrc

rece iver may bc

Tlrese include the arrangement

thc

comfort

good

of

a location

is

high

be as

for best

etc.

orceranric insulators. No. 12 to

the

down

L. Antenna

available.

such as a water

receptacle

ancl

electrical

of listening enjoyrnent arc

for

is self-contained,

required for

practical

as

reception of

and should

,

(uninsulated)

lead for

information

Book"

of the

antenna

and connect the

providing

subject

convicncc of

ground

recommend-

the

DX-75

distance

and as long

short wave

away from

be

attached

is best

arrestor

protection

on

antenna

published

many

#2

to

the

#l

pipe.

Plug the

tl'rc

and an

re-

rule an

power

against

other

termi-

termi-

ff7

VAC

to

to

for

by

be

VOLUME

turns on

knob

BAND
switches antenna and local oscillator

ious tuning bands.

Ciockwise

powcl

rotation

and increascs

SE,LECTOR Rotation

Index numbers are

of

volume.

of

the Band

t]le

Volurne control

Selector knob

circuits for

located

the

near

var-

the

knob and at each end of the diai.

TUNING
tuning

BANDSPREAD
a fine tuning

mally

After
the rnain
reduces

BFO
Beat

!-requency

lation

usecl
contains no modulation
ceiver
range
signals

ANL
the Automatjc Noise
mize

downposition may
weak
er level

REC

/

this

slide switch to
turning
position
tion

without warTn-up or retuning.

PHONE
(50

to

nal

speaker.

vary the volume

Rotation

indicator

adjustmcnt

indicator

the

the

approximate

tuning

the

frequency

Clockwise rotation of

of the IF

fol single side band

proper

for

of this control

other than

ln

ON

of the Tuning

(red)

to move across

Rotation

should

of
the reception

of

be adjusted to the

knob causes

the

Bandspread

the dial

frequency has been tuned

lcrob, tl-rc bandspread

pinpoint

for

Oscillator

and

adjustrnent

selection

the

BFO

increases

control

signalby tlris oscillator. A

or

code telegraphy purposes,

must be

and

reception

may also

(Note:

improve

modulated in
settings in the

reception of

CW type).

position

rfie

up

this slide

.

loob

frequency.

SET

of

turns

the % of

CW signal,

switch

Limiter circuits designed

background noise, static, etc. Operation

benecessary

signals since the noise limiter

for reception of

suppresses

signals.

power

The

receiver

the STBY

to

the nrbes. Switching

may

be silenced

position

instantly returns tlle receiver

jack

This

provides

which

The

Volume control functions as

at

tie headphones.

aconnectionforheadphones

automatically

by moving

witiout actually

to

back

to normal

silences tlre inter-

STBY

off

1000 ohms)

the

main

affects

Nor-

position.

by use

gradually

signals,

on

modu-

the re-

lov/er

weak

activares

to mini-

in

the very

low-

all

REC

tfie

opera-

usual

of

a

as

t

,l

the

to

2

TUNING

SET
FULLY

CAPACITOR

CLOSEO

FAST

LOOP

E

CORD

TUNING

SET
FULLY

CAPACITOR

CLOSEO

SPRING

HERE

FASTE

G'

3_LooP

TURt{S

3_t/2

coRD

AROUNO

MAIN TUNING

(REAR

SHAFT

DIAL

VIEIV)

CORD

Fig.

LooP coRD 2-t/2-''

TURNS AROUND

BAND

SPREAD DIAL

(

VIEIY)

REAR

I

Dial

Stringing

Diagram

CORD

SHAFT

,ffit

s

c3
2-25

c4

4-40

c5

4-40

7

reov

R7

looK

c22

.olpt

---

I

I
I
lc24

I

i

L--

L
I

R22

IK

){

f3-

R2
t.5K

g.F.o.

:

c6
4-40

I

c27

30

c7

220

ct5

.OO5Pf

clo

t.o
R3

roo

R4
47K

VIB

lz,

eCuea

"/

.{

I

{as

I

=

sw

oN

470

4

B.F.O.

ALL RESISTOR

ALL CAPACITOR

VALUES

IN

ARE

VALUES ARE

A I/2WATT

OHMS

IN MICROMICROFARADS UNLESS OTHERWISE SPECIFIED.

UNLESS

OTHERWISE SPECIFIED,

s

4

8.F.O.

CONT

v2

I28A6

o,
.1 ST8Y.

I

=

+7ovj

I
I.otpt

-

sw

3

REc.

c26

R24

IOOK

Rll

2.2M

T­I

I
l

rC

t28

R23

4.7K

V3

I2AV6

V4

6AQ5A

JI

PHONE

rt

c38

.oo5l

EO

cRl

3004

Rt9

250

clD
40pl

350v

stv

crc

lOpf

350V

-75

DX

/ii-\

ey/

,ri-3-l

t'_J

.t@

.o@

,-.@

cs@

cq@
cs@
ceO

15@

L6@

(O

u

z

L8@

o

cu@

crz@

gs@

qq@

Fig. 2 Chassis Layout Diagram

*

A LIC;NMENT INSTITIJC'f

IONS

Equiptnr:nt

l.

Oscilloscopc

2,

RF

IF Alignnrent

1.

Looscly
into

sition

2.

Corulcct
With

3.
nal
rnunl recovcred audio.

RF Alignmcnt

l.

Prcliminary set

NO|E:

These

rcquirccl

a, Oprcratiol
b.

c. Modulation

:

with

gcncrator-

Signal

Attenuation

pcrccnt.rges

tron

couplc a 455

thc

antenna temrinals

#l)

oscilloscopc to

gcncr.rtor:'sct to

signal

levcl,

1rcak

a, Bcgi,ruring

tightly closcd,

Iows:

C3
C4 3/4 Ttrn
C5 l/4
C6
Crl 1/'2
Clz
Cl3 l/4'furn
C 14 l,z4

b.

llcginnirg
just

as

follotvs:

L2
L3
L4

L6
L7
L8

settings

are approximate

calibratcd

capablc

fronr

below
at I KC wich

IF-

all

up

vcrtical scalc
of:

455

KC to 30 MC

lpv

output

KC, 50/u

(Bancl

spcaker

lowcstu.scablc

transfomrers

with all tr-imnrer

o1r:n

thc trinrn)crs

I

/4

7

/8

l/4'furn

$itlr ail

slugs at top of fonn ad-

l5

Turns

22 Turns

l5 Turns

Turns

30
22 Turns

Turns

30

'I'urns

15

and are

variablc modula-

modulatcct signal

po-

for

in

sig-

nrexi-

Sclector

tcrminals

calrecitors

fol-

as

'I'urn

Tuln
Turn
1-urn

'furn

NOT

final-

RF Alig'nmcnt

Z. Final

ln t-lrc

ilicd
antenna tcrminal.

Iator

rccovcrcd

cornlxrncnts first.

Iland

2

4

NOTE:
ordcr
caclt band, until
taincd.

The

shown, anrl

(con't.)

A-lig'nrncnt

following

frcqucncy

tuncd circuits arc adjustcd for

atrovc adjustrncnts should bc madc in tlrc

proccdurc,

(ltJ/u

Thc antcnna and

audio, always adjusting thc oscillator

Signal

Dial

600 KC

1400

I,8

4.3 MC

5.0 MC
lr.0 Mc

lr.0

30.0

shoukl

bc rcg.:atc-d

propcr

trackfurg and

a signal of

ntoclulat-ctl) is {cd into

Frcq.

and

Sctting

thc spcc-

local

maximum

Adjust

for

Maximunr

L5, LI

KC

MC

cll,
L6, L2

ctz, c4

L7,
c13, c5

MC
MC

calibration

scvcral

L8, L4

14,

c

[inrcs on

oscil-

c3

L3

c6

arc ob-

thc

7

PARTS

LIST

I'TEM

VI

v2

V3
V4

CI

C2

C5
C6
C7

rra

rro

cr0

cll
CT2
c13

c14
cl5
c16
c17
cl8
cl9
c20

rtt 1

c22

c23
c24

a)E

c26

c27
c28

c29
c30

NO.

DESCRIPTION

TUI]ES

CAPACITORS

-20

-10 -4Oprfl350V

40

GMV

.0lpf

2-2Spf

Ceramic Trirnmer

-40pf

4

Ceramic

4-40pf

Ceramic

4-40pf

Ceramic
22Opt tl\/o
Main Truring
Bandspread

l.Opf t10/6

-

luuill

/

4-4opf

4-4opf
4-4Opf

.005uf GMV

Bzpf

.Olpf

560pf

1800pf

3900pf

.0lpf CMV
.0lpf GMV

SEE
SEE

SEE
SEE T4
30pf t57"

ueramlc I rlmmer
Ceramic
Ceramic

Ceramic

-

l0!i N750 600V
GMV
t5lo

15% 125V

t5[

.Olpf GMV

T3
T3

GMV ZsU 500V

.0lpf

t5%

30pf

NPO

'T4

NPO

-350V

Electrclytic

Z5U

500V Cerarnic

Trimmer
Trimmer
Trimmer

NPO 500V

500V

Z5U

Z5U

125V

l25V Polystyrene
ZSU
ZSU

Z5U

Ceramic

Composition

Trimmer
Trimmer

Trimmer

500V Ceramic

Ceramic

Ceramic

500V

Polystyrene

Polystyrene

Ccramic

500V

Ceramic

500V

500V Ceramic

Ceramic

500V

Ceram.ic

500V

Ceramic

PART NO.

6CL8A

128A6
I2AV6

6AQsA

-350V

-338 -

301

-338 -2

301

-150V

r

ITEM

-? I

t- 2)

c33
c34

r.?c

c36

c37
C3B
c39

c40

RI
R2
R3
R4

t(5

R6

R7

R8

R9

RIO

Rtl

R12

Rl3

R14

Rl5

R16

r7

11
R18
Rl9
R20
R2 l

a),

R23
R24

NO.

DESCRIPTION PART

CAPACITORS

t20J,

22opt

t20fi

00lpf

NOT USED

!2ffi

.001pt

NOT USED

.0lpf CMV ZsU 500V

CMV ZsU

.()05

GMV

.005

250Y Elcctroiytic

40ttf.

/

GMV

.0lpf

RESISTORS

Variable

2M

l.5K Variable

tl0%

l00ft

tlj% l/2W

47K

110%

3.3M
t10% 1/2W

lM

tt0%

l00K

!10% I/2W

4.7K
tl0%

4700

1l0t;

27in

tl0T

2.2M
t10% l/2W

47K

!I}a/(.

47OK

tl0%

10M

!10%

270K

!1070 l/2W

470K

lI0To

47Gt

tlO%

l&A

25A1!n%

110%

lK

!rO%

4.7K
tl0% l/ZW

rK

!

4.7K

i00Ktl0% r/2W

l07o I/2W

(CONT.)

Z5lr 500V Ceramic

ZSU 500V Ceramic

Z5U 500V Ceramic

Ceramic

500V Ceramic

Z5U

Z5U

l/2W

1/2W Carbon

1/2W Carbon

l/2W
l/2W

1/2W

t/2W Carbon

I/2W

I,/2W

I/2W

i/2W

sW W.W.

l/2W

l/ZW Carbon

5U0V

500V

Carbon

Carbon

Carbon

Carlrcn
Carbon
Carbon

Carbon

Carbon

Carbon

Carbon

Calllon

Caitx>n

Carbon

Carbon

Carbn

Carbon

Carbn

Ceramic

Ceratnic

300

rot

-268

-7

34

-

-6

NO.

l8

I

PARTS LIST

(CON'T.)

NO. DESCRIPTION

ITEM

TRANSFORMERS

TI

lz

.r?

T4

LI
L2

LJ

L4
L5
L6
L7
L8

Power
Outprt Transformer
IF 455KC
IF

455KC

COILS

RF

Band
RF Band
RF Band

RF Band
Osc, Band
Osc. Band
Osc. Band
Osc. Band

Traasformer

#l
#2
#3
#4

#l
#2
#3
#4

PART

-685

500

-335

301

1655-6

-6

1655

-340

301

-34

301
30L-342

-343

30r

30r-344

-345

301

-346

30i
30r-347

NO.

NO.

ITEM

MI
M2
CRl
cR2

J1

SPK

T

l

DESCRIPTION

MISCELLANEOUS

Dial Light
Dial Light

Diode

400PIV 500 MA. ED-3004

Diode

400 PM00

Phone

Jack

Speaker
Cabinet

(Front)

Panel

(Back)

Panel

(Bandspread

Knob

(Band-Volume)

Knob

(BFO)

Knob
Dial Glass
Feet

MA. ED-3004

-Tuning)

PART

#1813
#1813

I6-2

14826
600-r73-3

5W-787
soo-629-2

-

27

L

OO2

27OO2P-1

26600P-r

-336

301
r00-435-1

NO.

l

swl

sw2

sw3

sw4

sw5

SWITCHES

Power

Switch

(On

Volume

(On

ANL

STBY-REC

Switch

BFO

(On

BFO

Band Switch

-

Off)

Control)

Control)

-268

300

ss-32

SS.32

-7

LOr

-339

301

-

34-6

18

9