Zenith Zenith_R-520 Service guide

D

DEPARTMENT

OF

RADIO

RECEIVER

R-520/URR

THE

ARMY

TECHNICAL

MANUAL

DEPARTMENT

OF

THE

ARMY • ';2..

,

]ANUARY

1954

TM

11

- 877

TECHNICAL

No. 11-877

CnAPT£u

Sec lion

Ct1APTER

Section

CnAPn}n 3.

1. INTRODUCTION

I.

JI. Description

2. I. Service upon receipt of equipment ___

II.

III.

IV. Operation under

SecLion

I.

II. P reventive maintenance s<'rvires

III. Lubrication

IV.

CHAPTJ::R CHAPTER

Section

C11APTt;n

.i.

5.

I.

JI. Repair:;___ _

III.

IV.

6.

Section

1.

II. Demolition of nrntcricl to pre,·ent enemy

APPEND

IX

I.

II.

INDEX.

~L.\KUAL}

RADIO

General. _ _ ___________________ _

and

OPERATIXG Controls __

Operation under usual condil ions ____

ORGAxrzATlONAL

DEPART~lEXT

w.,smxGTOx 25,

D.

OF

C.,

RECEIVER R-520/URR

do.to.

I:-.STRUCTIO'>S

111111s11t1l

_ _ _ _ __________ _

_____ • __

_

l'o11ditions __ _ _

~IATl\TENA:\CJ·;

STRUCTIONS

Organizational tools t\nd equipment

and

wt~nt

herproofing. _ _ .

Troublc~hooting

level__

THEORY

FJELD

Troubleshooting nt

Alinemcnt Jt'inal

SII!Pl\IENT

Shipment,

REFEREXCES. IDEXTIFICATJO'\

~IAI:\TE\.\::\CE

tcstin~

DEMOLITION'

USE

P

ARTS.

at organizational mai11tcnancc

fil-ld

maintenance level _

-------

proccdun·~

---

AND J,T:\llTED

TO PREVEN'T

and

limited i-torage _

.

OF

___

_________

----- -__

------

..••.•

I'.'\STR(;CTTO\S

_ _ _

---··

-- --

---

STORAGT·~

______ ---

-----

AND

E~E'.\IY

------

U$C

-

REPLACEABLE

THE

12

January 1954

l'araomph

_

I'.'\-

_

-

_

Ul-101

102,

101, 105

•••

AR~lY

I, 2

:J-8

!)-1.j

15.

1U

17-

2:$

21 27

28,

29

:30-:H

:~!i

-37

38

11

·12-59

GO

76

77-7!1

80

Ha

103

Paoe

7

12 21

23

27

29 29 34

35

41

64

82

85

98

103

105

108

128

1

WARNING

Be

careful

when working

not

on

HIGH

is used

of this equipment.

A

DANGEROUS

may

result

to observe safety precautions .

to

contact

or

near

VOLTAGE

in

the operation

if

operating personnel fail

external powe;r source

this equipment.

SHOCK

input

connections

3

ARTIFICIAL

GENERAL

l.

unless

the victim.

2.

rain

d turned sideward n structlon

3.

Remove

the

4. Begin artificial respiration. Continue int

erruption until dead. Jutely essential.

5. When

sen

loo should receive ficial technique when

6. When the victim tight susc1tallon, keep covery

7.

Don't able, use It, but, since mechanical resuscitators effective delay

BACK-PRESSURE

l.

Position

Bend side, placing his cheek upon

2. Position

head, close knees head are

fust below the l

th

umbs touching

3.

Oomprension Phase. Rock

vertical slow. steady, even, out

o!

downward on

4..

EJ:cpansion

commence arms Apply shoulders. Don't arms ing

on the chest muscles, arching the back the chest.) Drop the the cycle.

5.

Oycls

Use a steady unllorm of about equal len

th

e compression

1

m nlmum duration.

6. Changing Position

<a>

knees during the procedure. provided you don't

~~rve

etharm.JJ!t.

t

o e ease

Be (b)

ou~are

iiie

..

~~~~~c~"Jent

away.

PRINCIPLES

Seconds count! Begin

you

must.

Don't

Start

Place

!rom

victim's

Try

the

natural

hJs

elforts

seems certain.

wait

than

manual

resuscitation!

the

victim's body

the

respiratory

o!

the

ever fle:ced forward;

the

respira

any

troth

ton~ue

natura

to keep

victim

clothing; remove it,

adequate

for

breathing

to

him

for

mechanical resuscito.llon!

properly

resuscitation

ARM

of

his elbows; place one h?nd upon the other.

lacing

to

i!

Place

just

wlll

how you rock forward with the back-pressure

/~you

Victim.

of

Operator. Kneel on your l

him. Your knee should be

his

forearm,

you find

and

the

Timing

Remember

u not

· e ease a

it

more

your

hands

ower

spread

allow

the

downward

lungs. Keep

the

back. (See B).

Phase. Release

to

rock

above

be

<See c and

backward

the

enough

elbows,

lift

bend

drawn toward you. (The

and

Rlrythtn.

gth

and

that

The

rocking motion helps to

o!

operation.

Ure

and

to

break

~o{e

al

loosen clothes,

tory

or

debris from the mouth with

forward.

l breathing

the

rhythm

starts

breathing_, or when additional help

attention. Don't

these measures. Do them only when you have help

has

ls

breathing,

breathe. Synchronize

lying down until seen by a physician

per!ormed

for

LIFT

METHOD

Place

the victim lus hands.

your

foot should

comfortable,

on

the

tip

oJ

your

forward

weight

your

slowly.

and

to

feel resistance

your

elbows. As you rock backward, the victim's

arms

gently

DJ. Now,

rate

or

Press, Release, Lift, Release. Lon/fer counts

should be given to the

expansion phases. Make

or

Operator.

you

can

another t.he

rhythm

in

!rom

ter

one

o!

RESPIRATION

once!

Don't

take

Get

in

a prone position, so

pMsaees.

passages

i!

started.

It.

fiat

his shoulder blades. With the tip of

fingers downward

of pressure up.on your

elbows

the pressure, avoid

draw

repeat

Repeat

use

person

the

the "Lift-Release" phases,

apply

air

Jn

the lungs!

The

the chin shouldn't sag, since ob·

may

occur.

It

rhythmically

starts

smooth. Split-second timing

its

wet; keep the victim warm. Shock

Interrupt

adjust

your liming to assist him. Don't

your

I!

"push-pull"

In

the

eft

or

at

the sfdc of the victim's head

be

near his elbow. Kneel on both

with

of

the

one knee on each side

the victim's back so

until

your

upper

pal't

straight

Place

your

his

arms

and

arm

lift

the

ground

the cycle.

the cycle

and

to

"Press"

either

or

sus

Is

available you

In

changing. Move to one side

other

side. Your replacement begins

time

to

stimulants

head should he

or

the victim is pronounced

move the victim

or

try

You

may

that

your

save a life!

any

fluids will

e)Ct~nded

fingers.

and

without is

ls

to

warm

Draw

not available

the rhythmical

efforts

with

his.

After

or

until re·

o.n

approved model

are

only slig

manual

prone (iace·downl positjon.

rlght

arms

uf

and

upward

tension

expands the chest by pull·

relieving the weight

or

10

the

both knees

break

tain the

technfque.

Turn

knee,

and

outward.

are

your

body

hands. This to1·ces ah·

press

almost

any

finish thrust,

arms

upon the victim's

and

at

floor. This completes

to

12

times

and

"Lilt'

"Release" periods

the rhythm. Ob·

and

backward with

rhythm can

Is

avaJJ.

htly

mor~

never

his face to one

at

the victim's

that

approxim

of

their heels

your

(See

ate

lU

l!xcrt u

directly

and

toward you.

the victim's

per

minute.

steps

or

can

shl1t

and

odds

"take

tur

ns."

and

Jet

as

you move

and

any

abso·

artl·

or

re·

the

Al. ly

on

of of

Tt.1

AR·I

4

•

..

..:

A.

c

0

-

•

..

•

A.

E

0

"

•

E

..

-

"

-

>

.,,

c

..

0

..

•

A.

0 0

-

c

0

..

·-

•

0

A.

-

•

-

..

•

E

..

•

-

•

..:

A.

c

0

-

•

c

..

A.

M

Ill

A

..

-

E

..

-

•

..

..:

A.

c

0

-

•

c

..

A.

M

Ill

ff

.

II:

c

'S

...

c

u

5

Figure

1.

Rad

io

Receiveir

R-520/VRR.

6

CHAPTER

I

INTRODUCTION

Section

1.

Scope

This technical manual contains a description, a detailed theory of

op

eration, and necessary instructions for the installation, operation,

field

maintenance, and repair addition, a chapter on the disassembly and repacking of the receiver for

shipme

covering

2.

Forms

The following standard forms will be used for reporting unsatisfac-

tory conditions of Army

·preventive maintenance:

a.

filled

b.

out and forwarded to the scribed

c.

List for Finding, tions on the back

d.

Li

st Finding, Carrier, Radar), will be prepared in accordan tions on the back

e.

nt

or limited storage

a li

st

of

referenc

and Reco

DD

Form

out and forwarded as prescribed in SR 745-45-

DA Form

in SR 700-45-

DA Form 11-

Signal Corps Equipment (Radio Communication, Direction

Carrier, Radar),

DA Form 11-23

for Signal Corps Equipment (Radio Communication, Directi

Use other forms and r

rds

6,

Report of Damaged or Improper Shipment,

468,

Unsatisfactory Equipment Report, will be

5.

238, Operator First Echelon Maintenance Check

of

the form 9,

Second and Third Echelon Maintenance Check

of

form

I.

GENERAL

of

Radio Receiver R- 520/URR.

is

included.

es

and an identiiication table of parts.

mat

eriel and equipment and

Offic

e of the Chief Signal

will

be prepared

(fig.

12).

(fig.

13)

.

eco

rds as authorized.

Th

ere are two appendixes

in

5. Officer,

in

accordance with instruc-

ce

with instruc-

performing

will

fill

as

pre-

In

be ed

on

Section

3.

Purpose

a.

Radio Receiver R-520/URR (fig. dyne radio receiver designed in

a luggage-type carrying case. loudspeaker, contained within the unit, or a low-impedance headset connected externally.

b.

Radio Receiver R-520/URR is designed to receive a-m

(amplitude-modulated) signa

and

Use

II.

DESCRIPTION

for troop information.

Th

ls

covering frequency ranges from

AND

1), is a portable superhetero-

e receiver will operate either a

DAT

A

It

is contained

540

7

·

kc (kilocycles) to 1600 kc, 2

9.4

me to 9.8 me, 11.6

18.1 me.

The

frequencies are given

me

corresponding wave lengths in M (meters) for these

in paragraph 4.

dry batteries or from an external a-c (direct-current)

som·ce.

me

to

12 me, 14.9

The

types

(megacycles) to 4 me, 4

me

to 15.5 me, and 17,5 me to

Th

e receiver will operate from

(a.lterna~ing-current)

of

batteries and

on which the receiver will operat.e are listed in paragraphs 4,

4.

Techn

ical

Characteristic

Band

: Broadcast ______________ 2-4

MC

__________

4-8

MC

31 25 M ______________________ 11.6 me to 12 me.

19

16 M _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Receiver Type

Intermediate frequency

Number Rect

ifi

Thermal Power

A B

Power

117 volts 117 volts de ________________ _ 230 volts

2

30

Antennas:

Loop

\¥hip

Long wire. ________________ _

:Headset _______ _______________

Band selector

____________________ 4

M ___________________ _

M

----

-------

type

___________ ________

of signal

er-------

input battery

battery _________________

input

that

of

tubes ________________ 5.

_________________ Selenium.

resistor_________________ Glass-inolosed.

(battery) :

_____

(power line):

ac

___

ac

___

volts de _

___

________________

___

_____________ _____ _ _

__

-----------------

___

-----------

can

be received_ A-m.

______

______________ 9 volts

_____________ _

____

___

s

___

_ 540 kc to

_______ 2 me to 4

me

to 8 me

9.4

me

to 9.8 mo.

14.9

mo

17

.5 m c to 18. l m

Super

heterodyne.

455 kc.

at

90

volts

10

wat

ts.

7.5

watts.

20

watt

s.

15

watts.

Fastened

movable buildings broadcast

61

inches long (extended). Consists

eight

telescoped

the

ant

shortwave

Antenna

rear

of antenna assure weak signal

on

rear of

PL-55

nection (plug, cord,

supplied).

panel provide a band covering

_____

__

_____ _

_____

_ _

__

_

Jack

Seven band-sel

Frequenc~

1600kc me

to

15.5

67

ma.

at

17

ma.

to inside

to

and

band.

enna

circuit when

button

and

ground

receiver for connecting

(not

maximum

areas.

for low-impedance

ector

ran

ge

(555 M

(150 M (75 M

speaker

the

to

75 M)

to

37-}'2

mo.

c.

of

front

provide reception

vehicles. Used

sect

ions.

s is pressed.

terminals

supplied)

means

desired frequency range.

and

signal

accommodates

and

buttons

of selecting

me

exLernar

to

187

M).

cover.

Switched

any

one of

provided

ground,

pickup

headset

on

the

to 8 me,

or d-c

l power

12, and

M).

Re~

in

stee

on

into

the

exte

rnal

in

very

Plug

con-

not

front

the

13

the

of

on

to

.

l

8

Tone controL

Weight

Battery

Si

gna

l Corps batteries

Signal Corp

No

te.

5.

Packaging Data and

(fig.

a.

Radio Receiver R- 520/URR is shipped without batteries. When

it

is packaged for

one

smn.

each

receiver.

This carton is covered by

______ __

__

___

_________________

___

________ __________ ___ Zenith

or

s batteries _________

For

Signal Corps

___________

___

_________

battery

___

combinations, see paragraph

Four tone-control buttons loca

dial scale on tion of 16 different

20 pounds, less batteries.

type

battery

vol

ts

90

One 90-volt B Thr

ee 3-vo

Three

90-volt B Batteries BA-270/U.

Six

1.5-volt

Components

2)

expo

rt

or domestic shipment, two large bags

11

bag of silica gel are placed in the battery compartment of

Th

e receiver

is

placed in an inner carton and sealed.

a water-vaporproof bag which

FreQuencv

the

Z985 (not supplied). Single

pack consisting of nine volts A and

B supply.

Batte

lt

A Batteries BA-407/

J>i,.

Batteries BA-30/

13.

range

ted

front panel

to

nal combinations.

ry

BA-423/U.

below

permit

U.

is

placed

the

selec-

n.nd

in

an outer carton and sealed with pressure-sensitive, water-resistant tape.

outs

:four of th

id

e dimensions are listed in the following table:

ese

outer cartons are packed in a wooden crate. The

Item

Inn

er carton, 200-lb

rugated paper.

Outer carton, corrugated "'W'ooden

Not

b.

e.

Items

Th

crate ____

may

e following li

See the packing list

Crate dimensions

33

x 22X x 217i-----

c.

Radio Receiver R- 520/URR is the only component of the radio

set.

The

receiver measures

I

791e

inches lon

test

paper

_____________

be

packaged In a m

st

attached

(In.)

Four

each containing one receiver.

g.

It

weighs 20 pounds, l

, cor-

Height

(In.) (in.)

__

anner

dlfterent from

indicates the contents of each wooden crate .

to each crate for exact contents.

Contents

packaged car tons,

llXa

Width

14X

15%

33

that

inches high by 7

Depth

(In.

19X

20 22

,X

shown, depending on 'the supply channel.

Receivers shipped w

te

ries.

Spare

contained within

ess

batteries.

Volume

) (cu

W,Ys

10

21~

parts

8

It)

1.

~

9. 1

Notes

and accessories are

H2

inches deep

Unit

6

9

ithout

the

weight

(lb)

26

29

~

156

bat-

receiver.

by

9

6.

Description

a.

Radio Receiver R

of

Radio Receiver R

-52

0/URR

-52

0/URR

(fig.

1) is a five-tube (plus selenium

rectifier and glass-inclosed thermal resistor), portable, superheterodyne radio receiver designed to receive a-m wave bands.

The

front panel quired for the operation of the control and the control, and seven bands to be selected. When

it

catches and is held until another pushbutton is partially depressed,

at

which time the first pushbutton releases and the selector mechanism

is

disengaged. The broadcast range

on-off

band

switch, the

selector

butLons which permit

a band selector pushbutton

one band. The frequency range from 2

signals on broadcast and short-

(fig.

8) contains all the controls re-

r

eceiv

.,,

r. These include the

i:

..

iW

switch assembly, the

a.ny

one of seven

is

(540

to 1,600 kc) is covered by

to

8 me is covered

volume

tuning

depressed,

in

two

bands; one band covers the frequency range from 2 to 4 me and the

other band covers the frequency range from

bands

are referred to

bands cover the frequencies from

15.5

me, from

11.6

to

as

12

the

me,

continuous

17.

and

from 9.4 to

5 me to 18.l me, from

uses directly heated filament-type tubes and will operate on batteries

ac connecting areas. The external antenna

b.

with handl the connected

(9

volts A and

or

de. External antenna and ground terminals are provided for

an

external antenna and ground in extremely weak signal

90 volts B)

is

effective on all bands.

117

The receiver is built into a luggage-type carrying case, complete

e.

A loop antenna for broadcast reception

inside of the front cover.

by

an antenna extension cable to provide reception

The

loop antenna can be removed and

4 to 8 me. These two

coverage

bands.

9.8

me.

The

volts ac or de, and

is

Four

spread

14.9

receiver

dry

230

volts

fastened to

in

steel buildings and vehicles. For shortwave reception, the receiver has telescopic whip antenna cover is hinged for access headset jack, power adapter switch, and latch near the top edge of the door holds the rear cover

that

retracts into the cabinet.

to

spares, accessories,

a.ntenna.

The

rear

batt

eries, tubes,

connections. A

in

the closed

position.

c.

The chassis is removable from the carrying case for repair and

maintenance. Refer to paragraph

64

for chassis removal instructions.

to

a

7. A ccessories and

a. Included inside the cabinet of Radio Receiver R- 520/URR are

Running

Spares

the loop antenna extension cable and suction cups, four power cord adapter a nylon a:linement wrench, and

b.

su~h

resistor. Following is

10

p~ugs,

Running spares are provided for

the battery cable assemblies (contained in a bag),

an

instruction book.

all

normally expendable items

as tubes, pilot lamps, fuses, and the glass-inclosed thermal

a list of running spares:

5 fuses, 3/16 ampere, Sig

C stock No.

l neon pilot bulb, Sig C stock No.

3Z2592-1.

2Z5888-5.

2 tubes,

1U4. 1tube,1L6. 1 tube, 1U5. 1 tube,

3V4.

1 glass-inclosed thermal resistor.

8. Additional

The following material is R-520/URR, antenna wire; low-impedance headset; and headset

Equipment

not

supplied

but

is

required for certain operating conditions: 35-foot

as

part

of

Radio Receiver

Plug PL-55.

Caution: Do not make connections to the antenna and the ground

terminals

a.

(fig.

10)

while the set is connected to the power line.

Two terminals, marked A and

G,

are provided

at

the left rear

of the chassis for external antenna and ground connections. These are for use in areas antenna and ground are connected viously unobtainable are received in many cases (par.

b.

Under certain conditions,

of

extremely low signal strength. When an external

to these terminals, signals pre-

18c).

it

may be advantageous to use a headset (such as Headset HS-30-(*)) with a Plug PL-55 connected. The speaker into jack J3, located to the rear

is

disconnected automatically when the plug

of

the speaker (par. 51).

is

inserted

11

CHAPTER

2

OPERATING

Section

9.

Siting

External

~~nds

d

t~e

terrain. Radio Receiver R-520/URR: will have a greater receiving

ange r ooded wther

0

urrounding high terrain absorbs r-f (radio-frequency) energy. Weak

~r

other

under or lines, hospitals, or power units. Ch hilltop or an elevation. Normally, reception over water

over land. .

b.

Interior

urces of

so

ecautions to prevent conditions of extreme temperatures or excessive

:-oisture.

access to the front panel; leave enough leave space above the unit reception. For operation located within 6 feet power cable

I.

SERVICE

UPON

Requirements.

on local conditions, such as the type

if

the unit is high and clear areas, and other obstructions. Depressions, valleys, and

low places are poor locations

wise

undesirable

close

to

si~nals

steel

bnd~es,

Reguireme-nts.

electrical interference or mecharucal

In

a permanent installation, locate the receiver to provide

fro

of

the power source outlet unless an extension

is availabl

e.

INSTRUCTION

RECEIPT

The best location for radio equipment

of

for

may be

steel

oose,

If

possible, keep

to

extend the whip antenna for shortwave

m external power, the

OF

of

hills, buildings,

radio reception because the

e~pe~ted

buil.dmgs,

.

if

possible, a

~he

clearance for ventilation and

S

EQUIPMENT

housing available and

cliffs,

densely

if

the set is operated

.

underpasse~,

~ocat1on

is

better than

re~oive~

v1brat1ons.

away from

rocoivel'

must be

powe.r

on

Take

a

1

O.

Uncrating, Unpacking, and

No~.

For

used

or

recondjtioned equipment, refer

a.

General.

packing cases and, sometimes, in its equipment is received, select unpacked wi to the permanent or semipermanent installation The instructions in cases. Be sure all carrymg cases are present and the equipment is

undamaged. No special unpacking and uncrn.ting procedures are necessary for equipment shipped

Caution: Be careful not to damage the

uncrating, unpacking, or handling. Damage may necessitate a plete overhaul or render the equipment usel

12

Equipment may be shipped in oversea or domestic

thout

exposure to the elements. and which

e

bel~w

Checking

own

a location where the equipment may be

apply to equipment in domestic packing

in

carrying cases.

New

Equipment

to

paragraph

carrying case. When new

equipmenL

ess.

14.

is

convenient

of

the equipment.

by careless

com

-

b. Step-By-Step Instructions for Uncrating

Shipments

(fig. 2).

(1)

Place the imcking case as near till' opcraf.ing position as

ancl

Unpacking Export

convenient.

(2)

Cut

and fold back the steel straps.

(3)

Remove

the sides; the equipment may become

(4)

Remove the moisturnproof barrier and any excelsior or

corrugated paper covering

the

nails with a nail puller. Remove

wooden packing case. Do not

Lhe

equipment inside

attemnt

damaged.

to

lihe

pry

the

top of

off

the

wooden

packing case.

(5)

Remove one of the four cartons from the wooden packing

place

it

on

the

workbench or near i 1 final location.

dur.Ll~

(6)

case and

Inspect

Lhe

equipment for possible damage .ucurred

shipment.

c.

Opening Card

instructions are needed for ing

the

equipment from the cardboard carton.

d.

Checking. Check

e.

Unpacking Domestic Packing

boa

rd Carton and Waterproof Barrier. No special

ope11ing

the

contents against

the watetproof bn.rrier and remov-

the

packing slip.

Cases.

Radio equipment may

be

received in domestic packing cases. 'I'he instructions given in b

above apply also

that

tons

protect the equipment; if heavy wrapping paper has been

used, remove

to unpacking domestic shipments. Open the car-

it

carefully and take

out;

the components. Check the

contents of the packing case against the packing slip.

Note. Save the original packing cases and containers from both export and

domestic shipments.

for storage or shipment.

Th

ey can be used again when

the

equipment is repacked

11. Installation of Receiver

Radio Receiver R- 520/URR is shipped with the tubes, the power

l)upply adaptor, the fuse, and the pilot lamp installed. The receiver

t,o

is shipped without batteries and is ready

For

a-c power source. or d-c source,

refer to paragraph

are included on the inside

12.

Connections

operation from a 230-volt d-c or 117-volt a-c

12.

Running spares and accessories

of

the

receiver case

for

Power Line

Ope

Reach through the finger grip, located near the center of

the

door of

cabinet, and release latch

A7

operate from a 230-volt,

(fig.

3).

ration

(fig.

3)

by

pushing upward.

the

rear

While holding the latch in the released position, open the door by

that

pulling outward on the finger grip. Be sure adapter switch, located on power supply adapter correct position to conform to the type of power from which the

is to be operated.

To

move power snpply adapter switch 85, loosen

the power supply

Zl

(fig.

4), is in the set

13

14

Figure

f.

Packing and packaging

C

ORRUGATED

INN

ER

CARTON

SEALED

of

Radio Receiver R

-5f

0/URR

TM877- 2

.

0 " 0

&

Figure

S. Spare parts and

accessories.

knurled thumb bolt H3, that holds switch positioning plate N2

5). Move the switch

a.

Th

e following table lists the types

the receiver

will

to

the desired position and tighten the bolt.

of

external power from which

operate and indicates the proper power supply

adapter switch position for each type.

Type

or

power

105

to

130 volts

105 to 130 volts de __________ ___________________________ 205

to 230 volts

205 to 230 vol ts ac _____ __

b.

Remove the fuseholder cap

amine fuse

ao·-----

d0-------------

Fl. Use

-----

---

------

__ __

________________

only a

~s-ampere

------------------------

-----------------

at

__________

the rear

lX- by

of

the receiver and

X-inch

Warning: Do not use a fuse rated higher than

receiver

the correct voltage

may become seriously damaged.

c.

Determine whether the power source outlet socket can supply

for

the receiver

(a

above). Determine whether

85 sd3ptor switch

110

_

110 220

--

_

220

fuse.

~o

ampere; the

positions

V.

AC-DC. V. AC-DC. V.

DC.

V.

AC.

the power line cord plug will fit the power source outlet socket. the

plug will not fit into the socket, select one of the four power line

(fig.

ex-

If

15

..

••

....

,,

..

Figure 4. Radi-0 Receiver

R-520/URR,

rear view, back

cover

open,

sh-Owing

typical battery comt>lement.

Figure

5.

Power

supply

adapter

Z1.

T

M877·'4

3011011-55

- 2

17

cord adapters located inside the case

socket

(fig.

4). Figure 6 shows the power line cord ada?ters m e

that

will

m

. d t

i1

~

t · t the outldt

0

fi

Plug the power line cord into the adapter before makmg connection

to the power source outlet. . . e

d.

On direct current, the receiver will operate with

position only.

on, reverse the plug. reverse

the

If

the receiver fails to operate after havmg been turne

On alternating current,

plug for minimum hum or noise.

it

~he

plug m

may

be necessary to

ond

·

TM877·S

Figure 8. Power line cord adapters.

13. Connections for Batte

Radio Receiver R-520/URR is designed to operate from self-contained battery pack several combinations of commonly available

ry Operation

(Zenith

Z985,

a.

single

not supplied) or from one of

Signal Corps batteries. Several combinations of Signal Corps batteries permit operation with the

ba

tteries

that

a.re

self-contained, while other combinations permit

operation with the batteries that are located outside the case.

a. Place a Zenith battery pack

Z985,

if available, in the battery

compartment located below the receiver chassis and insert the plug of battery cable plug of line cord of the chassis.

18

Wl

into the receptacle on the battery. Insert the

W2

into battery switch socket 84, on the top rear

Stow excess cord

a.a

shown in figure 4.

b.

Red harness

W4

(contained in the cloth bag inside the

battery compartment) can be used with the Signal Cqrps battery complement shown in figure 3-volt A Batteries BA-407 receiver battery cable

4.

One 90-volt B-Battery BA-423/U and three

/U are used. Inse

Wl

and the four

rt

the harness between

Sig~a

l

Corps batteries.

In

addition, red harness W 4 will accommodate the following listed alter-

nate

battery complements within the battery compartme

Three

batteries

Ono

battery

nt

of the set.

BA-407/U BA-407/U BA-407/U BA-406/U BA-406/U BA-406/U BA-406/U BA-408/U BA-409/U

c.

The folio

receiver,

wing battery combinations permit ope

in

conjunction with red harness W4, with the batteries

located outside the case:

Thr<>e

BA-406/U BA-406/U BA-424/U

BABA-407/U BA-423/U BA- 408/U

BA-408/U

BA-

BA BA-408/U BA-424/U

BA-409/U BA-416/U BA-409/U BA-419/U BA-409/U BA-409/U BA-423/U BA-409/U BA-4 BA-410 BA-410 BA-410 BA-410/U BA-423/U BA BA-411/U

BA BA

BA-411/U

BA-

- 419/U BA-416/U BA-415/U

BA-423/U

BA-419/U BA-416/U BA-415/U BA-415/U BA-415/U

batteries One battery

BA-420/U

40

7/U

408

/U BA-420/U

- 408/U BA-423/U

10

/U /U /U /U

-410/U

-411/U

BA- 420/U

BA-416/U BA

-4

19/U

BA-420/U

BA-424/U BA-415/U BA-416/U BA-41

9/U

BA-420

/U

BA-424/U BA-415/U BA-416/U BA-

419/U

-42

0/U

BA

rat

ion

of

the

19

Three batWles

One battery

BA-411/U

BA-411/U BA-412/U BA-412/U BA-412/U BA-412/U BA-412/U BA-412/U

d.

Figure 7 shows the batteries

harness

W5

in the general position they occupy within the receiver

BA-423/U

BA-424/U BA-415/U BA-416/U BA-419/U BA-420/U BA

-4

23/U

BA

-4

24/U

that

are connected

by

yellow

battery compartment. This harness is connected permanently to battery case E23, which is supplied with the set. front end

of

the battery compartment and permits operation with the

It

is located

at

the

Signal Corps batteries contained within the receiver case. To insert

six A Batteries given on the decal next the batteries, press down wise.

Place the three B Batteries BA-270/U into position

battery compartment

P

IO

into the receptacle

BA-30/U into battery case E23,

to

the removable end cover E24. To remove

with the palm

and connect cable

of

receiver battery cable WI.

W6

SIX

follow

of

the band and turn clock-

W5

to them. Insert plug

the directions

f24

i.1

the

20

8L.ACK

HARNES~

ro,:t

VSE WITH

EX

TERNA

BATTER1E<

Figure

7.

Signal

Corps

battery

pack

connections

8AfTERV 8A

270/U

BATT

ERV

8A·270/V

.

e. With black

used

that

has

Th

e four connecting leads are tagged, showing

fig

. 7).

(

Ca

ution:

bility of accidently placing

harn

ess W6, any external

a 9-volt, d-c A supply and a 90-volt, d-c B supply.

Be

sure to connect the

A.

battery

the B battery

and causing a burnout.

Note. Insert

place

the

bag in the

battery

cables

that

compartment.

a.re

not being used into

battery

the

first

across

source can be

voltages required

to

avoid the possi·

the

tube filaments

the

cloth bag and

14. Se

rvice

a. Follow

Upon

the

instructions

Receipt

of

Use

in

paragraph

d or

Reconditioned

10

Equipment

for uncrating, unpack-

ing, and checking the equipment.

b. Che'ck the used or reconditioned equipment for tags or other

indications pertaining to changes any

changes

in

wiring have been made, note the change in this techni-

the wiring

of

the

equipment.

If

in

cal manual (along with the serial and order numbers of the modified equipment), preferably on the schematic diagram.

c.

Check the operating controls for ease of rotation.

is required, refer to the lubrication instructions (par.

d.

Perform the installation

paragraphs

11, 12,

and

13.

Section II.

and

connection procedures given in

CONTROLS

35)

If

.

lubrication

15. General

Haphazard o.peration or improper setting damage to electronic equipment. For this reason, it know the function of

pm

ent

equi

16.

is discussed in paragraphs

Controls and

0very control. The actual operation of the

17

Their

Uses

(fig. 8)

Cont.rol

of

the contr

through 23.

F.unctlon

ols

can cause

is important to

On-off switch Volume controL Band selector buttons

Tuning

Switch assembly tone con-

trol.

____________

___

______

control_ _________ _

____

_

Turns receiver

_

Varies

_

volume Selects the Selects desired frequency by

mechanism and ganged tuning capacitor.

Adjusts tone

preference by means below buttons in either possible tone combinations.

on

and

off

.

of

audio

output

.

band covering the desired frequency.

of

the receiver to listener's individual

of

the

dial. 'The combination of these four

of

their two positions offers

means

four tone buttons

of

a.

dial

16

21

DIAL POINTER PILOT LIGHT

VOLUME

AND

ON-OFF

'--

CONTROL

SWITCH

~~~--~~--.../

~TONE

Figure 8.

CONTROL

SWITCH

ASSEMBLY

Rad

io

R

ecei11

er R-

of'""""

.....

. "9

oll doy

"'°'"'

""

••other

mOl•n•

a

omottvr

Wtolher •

"'OflM.

SWb<oo4c:oo1

broodcott

6f0/URR

•

~

Illa]

~

mIJ

lmjf]

llllltJ

~

, f ro

nl.

TUNING

pa~l.

c

BAND

CONTROL

SELECTOR

BUTTONS

TM877·8

Section

17.

Note.

paragraph 41,

a.

which the set

b.

clicks and the neon pilot light

Ill.

Starting

Procedure

If,

during

the

OPERATION

the

starting

equipment performance checklist.

UNDER

procedure,

USUAL

an

abnormal result is obtained, refer

CONDITIONS

Prepare the receiver for operation from the power source from

is to be operated (pars. 12

Turn

the volume control

on-off glows

a.nd

13).

switch knob clockwise until (fig.

8). Continue to turn the

to

it

knob clockwise until the desired volume is obtained. When tuning

fo

r very weak signals,

it

may be necessary to turn the volume control

to the maximum clockwise position.

c.

Choose the band

that

covers the desired frequency (par. 4). The color of the letters

and numerals on

corresponding

1

8.

Standard

scale

Broadcast

The broadcast band portion section indicated calibrated in kilocycles with the

(fig

. 8).

a. Normal Conditions.

(1) Press the buff-colored band selector switch button marked

of

operation and press the band selector button

ea.ch

band selector button is the same color

on

the dial.

Reception

of

the dial scale is the buff-colored

by

the lower half

of

the pointer. This secti

last zero deleted

for

convenience

as

on

the

is

BC.

(2) Tune with

back and forth slowly to obtain

(3)

After a station has been tuned in, readjust the volume

the

tuning control knob

(fig.

8).

a clear signal.

Turn

the knob

control to the desired volume.

(4) Adjust the tone control buttons for the desired tone.

b.

Steel Structures and Vehicles.

(1) Remove the

in

position on the inside

the

antenna and replace the knurled nuts

knur

led brass nuts

that

of

the front cover

hold loop antenna.

(.fig.

9). Remove

to

prevent their

E2

loss.

Caution:

Do

not

make

connections

to

antenna and

ground terminals while the set is connected to the power line.

(2) Open the rear door

cable

W3,

and suction cups

(3)

Remove plug

Insert three-pronged plug extension cable other end

of

the cabinet and remove loop extension

015

and

016.

Pl

from the loop antenna. socket

P8, located on one end

W3,

cable

into receptacle

W3

on the loop antenna and snap the

Jl

(fig.

28). Snap the

(fig. 10)

of

loop

suction cups on the two remaining loop antenna snap fasteners.

(4)

Moisten the suction cups and apply the loop antenna to a

corner of

a window.

23

I

,

.

LC<lP

All

MOUNTED

TE

NllA

Cll WlllOOW

LOO

I'

AllTHHU

OISCO

El

Pll

Mll

BETWlEH

S

\1111

CH

PLUC

(C

TEO a OR

TUI£

.AllO 8.AllO

'UP

PORT BRACKET

ES

SEO

Figtire 9. Extension cable connected

(5)

Continue ·with the procedure for operating tho receiver

outlined in

(6)

Experiment for best reception and minimum noise by placing

the loop antenna in various positions on the window

c.

Antenna and Ground (

are provided

at

paragraph

the left

W3

17

and in a above.

fig. 10). Two terminals, marked A and

rear

of tho chassis for external antenna and

Z E H

l

ITtf

98

5

lo

loop antenna.

s.

T

M077

- 9

G,

ground connection. These are for use in areas of extremely low signal

By

strength.

connecting

terminals, signals previously impossible to obtain many cases. Ordinary field may be used.

as high

and

Erect

as

possible above the ground and the sw-rounding terrain. Bring down the insulated lead-in wire and connect Under some conditions,

to the G terminal.

The

an

external antenna and ground to these

ar

e received in

wire, such

an external antenna

it

may

be necessary to connect

as

Wire WD-

at

1/TT

or W-110-B,

least

35

feet in length

it

to the A terminal.

n.

good ground

external antenna and ground are connected automatically to the proper standard or shortwave circuit when the operator presses the band selector buttons.

24

BAND

SWITCH

SUPPORT

BRACKET

EXTERNAL ANTENNA AND

GROONI> TERMJNALS

Figure 10. Antenna and

19.

Shortwave

Th

e six shortwo.

in me.

Four

two on the lower half.

Reception

ve

bands are spread and calibrated

bands are located

Read with the upper half or lower half

the pointer, depending on the

loco.tion

gro

und terminal

on

the upper half

of

the scale in use.

wave operation, proceed as follows:

a.

Rai

se the front cover to an upright position.

b.

Tw·n the button on top

it

snaps up. Extend the

c.

Press the desired shortwave band selector button.

d.

Continue with the procedure for operating the r

in

paragraph 17.

of

the telescopic whip antenna

ant

enna to its full length.

TM877•10

s.

on

the dial

of

the dial and

For

short-

El

eceiver outlined

of

until

25

20.

Logging

(fig.

A logging scale

assure ease and accuracy

Example: A station heard

tuning band, and the number

scale, which,

Scale

8)

is

provided

in

this case, would be 40. Therefore, the station

in

the upper edge

in

logging and relocating shortwave stations.

at

6.9 me would be logged

of

divisions occmTing on the logging

be logged as 6.8 (40).

21.

Tone

Control

(fig. 8)

a.

The tone of Radio Receiver R-520/URR may be regulated preference below their two positions offers

of

the tonal range

b.

To cut the low-frequency response, set the ALTO, VOICE, and high-frequency response,

the left and the combinations of tone respons

of

the listener

by

me11ns

of the four button tone switches

the dial. The combination of these four buttons

16

possible tonal combinations. The portion

is

shown above each button.

For

normal response, all tone control buttons are set

BASS button

es

suited

TREBLE

set

BA

SS

and ALTO buttons

control button settings

to

different conditions.

buttons

to

the right. To lower the

the VOICE and/or

to

will

TREBLE

the right. Various

result

of

the dial face

at

in

to

the right.

to

the left and

buttons to

in

frequency

6.8

on

would

to

either

to

the

of

JJ

PLUG

PL-~6

Figure

WI

11.

Radio Receiver

ZENITH

z

98,

R-520/f!RR,

with headset connected.

TM

877·11

22.

Headset

(fig.

11)

Under certain conditions

such as Headset

PL-55 the plug into jack J3 (located to

is disconnected

are achieved

impedance match is not necessary.

23.

the left control knob fully counterclockwise until

the neon pilot light goes out. Rotate the tuning control knob counter-

cl

tuning range. This insures meshed and are afforded the maximum protection from mechanical injury while the reciever is

to the headset leads, open the back cover

Stopping

When the set is not

ockwise until the dial pointer is

HS-30-(*).

aut9matically when the plug

by

using a low-impedance headset; however,

Procedure

it

may be advantageous to use a headset

To

the

in

use, make sure

that

not

in

use the headset, connect a Plug

of

the case, and insert

rear

of

the speaker). The speake1

is

inserted. Best results

an

exact

that

the power

at

the low-frequency end

the tuning capacitor plates are fully

use.

is

off

by

turning

a click is heard and

of

the

Section

24.

Th

regions

the following paragraphs instructions are given on procedures for

minimizing the effect

25.

weather may affect the efficient operation

tions and precautions for operation under such adverse conditions

follow:

inclosure, construct the open air with a headset

Frequently, when edges this condition. Never them usel or action of the diaphragms. When this happens, remove the bakelite

cap into

IV

.

OPERATION

UNDER

UNUSUAL

CONDITIONS

General

e operation of Radio Receiver R-520/URR may be difficult in

of

extreme cold, heat, humidity, sand, mud, snow, etc.

of

these unusual operating conditions.

Operation

Subzero temperatures

a.

Handle the equipment carefully.

b.

Keep the equipment warm and dry.

c

..

Wear a knitted woolen cap over the headset when operating

of

the ears may freeze without the operator being conscious

ess.

if

moisture condenses within them,

and remove the ice and moisture.

d. When equip

a warm room,

in

Arctic

a headset without rubber earpieces is worn, the

If

water gets into the receiver portions

ment

Climates

anci

climatic conditions associated with

an

insulated box for the set.

that

does not include rubber earpieces.

flex

rubber ear caps; this action may render

it

that

has been

it

will sweat until

e>rposed

it

of

the equipment. Instruc-

If

the set is not

may freeze and impede the

to

the cold is brought

reaches room temperature.

in

of

the headset,

a heated

In

cold

in

of

27

This condition also arises when equipment warms up during the day

after exposure during a cold l1ight. When the equipment has roached room temperature,

e.

Use

any improvised means

will

fail

if

not protected against, the cold. Preheat the batteries.

To

pr

eve

nt

heat

dry

it

thoroughly.

to

loss, place them

protect

in

dry

baf,f,eries,

because they

bags lined with kapok, spun

glass fiber materials, animal skins, or woolen clothing.

26. Operation

When operated

installed

in

When equipment is installed below ground and when swampy areas, Ventilation

in

Tropical Climates

in

tropical climates, radio equipme

nt

may be

tents, huts, or, when necessary, in underground dugouts.

it

is set up in

moisturn conditions are more acute

is

usually very poor, and the high relative hwnidity causes

than

normal.

condensation of moisture on the equipment whenever the t.emperature of the equipment becomes

this condition, place

equipment

27.

Operation

(w

ith the back cover removed).

in

Desert Climates

a. Conditions similar

often prevail

in

desert

low

er than the ambient air. To minimize

lighted electric bulbs close

to

those encountered

area.a.

Use the same measmes

to

the rear of the

in

iropical climates

to

insw·e

proper operat10n of the equipment.

b. The main problem

desert areas is the large the moving parts of tion is to house the equipment

building

is

seldom available and would require air conditioning, the next best precaution is is

located as dustproof as possible with available material

wet sacking over the windows and doors; cover the inside walls

heavy paper; and

secW'e

prevent their flapping

c. Never tie power cords,

to the outside

or

inside of the

sudden wind squalls which

that

arises with equipment operation in

amount,

of

sand 01·

dirt

and dust

that

enters

radio equipment. The ideal preventive precau-

in

a dustproof shelter. Since such a

to

mak

e the building in which the equipment

s.

Hang

'vi th

the side walls of the tents with sand to

in

the wind.

signo.l

may

cords, or other wire connections

tenL.

jerk the connections

Dese

rt

areas are subject

loo

se or break

the lines.

d.

Be careful to keep the equipment as free of dust as possible. Make frequent preventive maintenance checks (pars. P

ay

part

icular attention

to

the lubricants.

30

through

37)

t,o

.

28

CHAPTER

3

ORGANIZATIONAL

MAINTENANCE

INSTRUCTIONS

Section

28.

tools found tained Army receiver is nylon alinement wrench 0

29.

radio set. One end of the wrench has a hexagonal shaft which

for the design allows the wrench to slip through or engage the i-f transformer prim

from the top of the chassis.

for adjustment

use

I.

ORGANIZATIONAL

Tools

~fost

a.

Tool Equipment TE-41.

b.

Special

Alinement wrench 0

the

and

Materials Used

of

the

repair and maintenance may be performed with the

in

Tool Equipment TE-41.

in

Tool Equipment TE-41 are listed

Supply Mnnual

Tools.

Alinement wrench

Materials.

Orange stick. Cnrbon tetrachloride.* Cheesecloth, bleached, lint-free.* Paper, Solvent, D1·y-Cleaning (SD) (Fed spec No. P-S-661a).

sand, flint No. 000. *

Tool

ad

justment

ary

or secondary coil core

alinement

SIG

6-TE-41.

0 14.

Supplied

of

the antenna, r-f and oscillator coil cores.

wrench

with

14

is

the

the i-f (intermediate-frequency) cores. This

The

as a screwdriver

TOOLS

with

Radio Receiver R-520/URR

The

14

AND

tools and equipment con-

in

the Department of the

only tool supplied with the

(fig.

4)

.

Radio Receiver R-520/URR

only special tool supplied with the

so

that

alinement can be performed

other end has a spade tip

to

turn

trimmer

EQUIPMENT

is

used

and

is used

Do

not

capacitors.

Section

30.

Definition

Preventive maintenance

when the equipment is to

avoid brenkdowns and needless interruptions in service. Preventive

maintenance diffel's from troubleshooting and object

750-5.)

•Part

of

II.

PREVENTIVE

of Prev

is

to prevent certain troubles from occurring. (Refer

'l'ool Equipment 'l'E-41.

enti

not

MAINTENANCE

ve Mainte

is

work performed on equipment (usually

in

use) to keep

nance

it

in good working condition

SERVICES

repair, because its

to

AR

29

31. General

a.

Keep

or

a dry brush for cleaning.

b. Inspect the equipment for faults

Preventive

the interior

Maintenance

of

the

set

Techniques

clean. Use a clean, dry, lint-free cloth

just

beginning

to

show, and make the necessary repairs. Locate and tighten loose mechanical parts, reconnect broken leads, tape frayed and repla

capacitors). Be sure are seated firmly

c.

ce

parts

that

appear ready to fail (scorched resistors, leaking

that

all pluck-out items (tubes, fuses, adapters)

in their sockets.

Clean the band selector switch contacts with carbon tetra.chloride only if absolutely necessary. Be careful chloride solution on the coils.

switch contacts and result

Caution: Repeated contact of carbon tetrachloride with the skin

or prolonged breathing of the fumes

ventilation

Note.

tightened beyond the pressure for which they are designed will broken. Be careful when tightening screws the threads in this material are preventive maintenance techniques, refer

32.

Use

a.

The decision as

is

provided.

Screws, bolts,

of

Preventive

(figs.

12 and

and

nuts should

Maintenance

13)

to

which items on DA Forms 11are applicable to this equipment is the case of first echelon maintenance chief or his designated repr third echelon maintenance,

It

may

in

erratic operation.

is dangerous. Be sure adequate

not

in

st

ripped easily.

to

TB

a tactical decision to be made in

by

ese

ntative, and, in the case of second and

by

the individual making the inspection.

Instructions for the use of each form

-0a

bles and wires. Locate

not

to get the carbon tetra-

cause a deposit

be tightened carelessly. Fittings

plastic

or

bakelite material because

For

further information on

SIG

178.

of

wax

be

damaged or

on

Forms

238

and 11-239

the communications

appef).r

on

the reverse side of

officer

the form.

b.

Circled items in figures 12 and

cable

to

Radio Receiver R-520/URR. References

13

are partially or totally appli-

in

the

ITEM

block refer to paragraphs in text which contain additional maintenance

information.

the

33.

Performing

a.

Check the radio set for completeness and satisfactory condition.

The

corr:ponents

and are illustrat

.

b.

Check suitability

t10n

(par.

c.

Remove dirt and moisture from the antenna., headset jack,

plugs and carrying case

.

d.

Inspect the seating of accessible pluck-out items: tubes, pilot

light, fuse

e. Inspect tone control switch

30

9).

Fl,

Exterior

of

ed

nnd

the fow· adapter connectors

Preventive

the radio set. are listed in paragraphs 5 and

in figures 1 3 4 6 and 7

of

J ' , , •

location and installation for normal

(figs.

4,

7,

9,

es,

tuning control, volume control,

Maintenance

and

11)

.

(figs.

4,

5,

6,

and 28).

7,

opera.-

and band selector switches for binding, scraping, excessive looseness, misa.linement,

j.

Check to verify normal operation (par. 41).

g.

Inspect the line cord, battery cables, and wire, for cuts, breaks,

fraying, deterioration, kinks, and strain (par.

h.

Inspect the loop and whip antennas

(

fi

gs. 9,

i.

Inspect for looseness

and positive action

10,

and 33).

(fig.

8).

13

and

figs.

4 and 7).

for

corrosion and loose fit

of

accessiblo items, tone control switches,

tuning and volume control knobs, band selector switches, jack J3,

connectors, transformer T3, capacitor

(figs.

4,

8,

28,

and 30).

j.

Clean

the

dial window and neon pilot light assembly

C45, and pilot light assembly

(figs.

1

and

28).

k.

Inspect the shelters and covers for adequacy

of

weatherproofing

(par. 9).

34.

Performing Interior Preventive Maintenance

Caution: Disconnect

all

power before performing the following

operations. After completion, reconnect the power, and check for

satisfactory operation.

a.

Inspect the electron tubes for loose envelopes, cracked sockets, bent pins, dirt

carefully; check

b.

di

scolo

c.

me

nt

d. Inspect

tion, and

e.

cabinets

j.

ment

g.

speaker 28

and

h. Inspect transformer T3

and

insufficient socket spring tension; remove dust and

the

emission

of

tubes.

Inspect fixed capacitors C25 and C45 for leaks, bulges, and

ration

(figs.

29

and 30).

Inspect variable tWling capacitor C2 for dirt, moisture, misaline-

of

plates, and loose mountings

the

resistors for cracks, chipping, blistering, discolora-

moistw·e

(fig.

29).

Clean and tighten the switches and interiors

not

readily accessible (par. 63).

Lubricate the equipment in accordance

of the Army lubrication order (par.

(fig.

28).

35

of

\'Vith

applicable Depart-

and

fig.

14).

chassis and

Clean and tighten the connections and mountings for loud-

LSl,

transformer T3, and potentiometers (par.

63

and

figs.

29). a.nd

potentiometers for overheating

(figs. 28 and 29).

i.

Before shipping or storing, remove the batteries (par. 103).

j.

Ins

pect the batteries for shorts and dead cells.

are swelling or oozing, replace them immediately.)

li

ght

does

not

glow on battery operation, insufficient

(If

the

batte~es

If

the neon

B+ voltage is

p

il

~t

indicated. Replace the B battery pack.

k. Check

l.

If

what a

fo

r adequacy of moisture-fungiproofing (par. 36).

deficiencies noted are

ction was ta.ken.

not

corrected during inspection, indicate

31

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33

Section

35.

Caution: Avoid contacting lubricating

such as rubber, paint, and certain plastics may have

Ill

. L

UBR

Lubrication Inst

(fig.

14)

ICATION

ructi

ons

AND

WEATHERPR

oil

or grease with materi

on

which the lubricant

a solvent effect. Avoid contacting lubricant with the

OOFING

drive cords.

a.

Becau

se

Radio R simple design, little lubrication is necessary. ganged tuning capacitor becomes

remo

ve

any g

rit

between the capacitor and driv

eceivt>

r R-520/URR uses a dial drive system of

If

the three-section

stiff and causes the dial cord

e sha

ft

bearing

Lubricate by applying Grease, Aircraft and Instruments

DRIVE

SHAFT

~~:r;-c

j:J:

.,.,_----1-GA

CAUTION: KEEP LUBRICANT

DIAL

N

GED CAUTION: PREVENT LUBRICANT CAPACITOR

CAPACITOR

LUBRICATION

PLATES.

CORDS.

FROM

LUBRICATION POIN

POINTS

AWAY FROM

.

SPREADING

to

surfaces.

(GL)

TS.

ON

dia

slip,

to

al

l

/l'igu

re

14. Lubrication pointt

th

ese

parts. Do not allow lubricant

for Radio Receiver Rr-5£0/URR.

to

spread

on

capacitor plates or

dial cord.

b.

Grease (GL) contains a rust and corrosion inhibitor. It can be

used

in

regions where the tempcratw·e ranges from -

+

160°

F.

36.

WeatherprooRng

a.

General.

climatic conditions such as prevail

region

s,

requir

insects, dust, corrosion,

ratur

tempe

b.

Tropwal Maintenance

proofing vides

a reasonable degree

in

TB SIG

34

Signal Corps equipment, when operated under severe

es

special treatment and maintenance. Fungus growth,

es

are harmful to mo

tr

eatme

nt

13

and TB SIG

Instructi

salt spra

ons

in

tropical, arctic, and dese

y, excessive moisture, and extreme

st

materials.

. A special moistureproo.fing and fungi-

has been devised which,

of

protection. This treatment is explained

72.

Th

e equipme

if

properly applied, pro-

nt

is moistw·eproofed

TM877·14

70°

F. to

rt

and fungiproofed

ment

only when

c.

Desert 1Vlaintenance. Special precautions necessary

equipment

low humidity,

7

5.

d.

poor performance or total operational failure of equipment

tremely l

e.

Lubrication.

and lubricants outlined in when operating equipment under conditions of extreme cold Refer

37

.

Cabinet

Olean

wate

l'.

shoe polish of the proper color.

failw-e in areas subject to extremely high t<'mperatures,

Winter Maintenance. Special precautions necessary to

ow

TB

to para.graph

the

Touch up scuffs and scratches with a good paste-type wax

at

the factory and

parts

are replaced

and

excessive sand

temperatures

The

effocLs

are exi>laincd

SIG

69

and pay sLrict attention to all lubrication orders

35

for detailed instructions.

Finish

outside of

the

it

is necessary to use this

or

repaired.

to

and

dust

are explained in

urc

cxpln.incd in

of cxt,reme cold and

in

TB

cabinet with a mild solution of soap

TB

SIG

66

and

TB

heat

on materials

SIG

69. Obsel've all pl'ecautions

TB

SIG

treat-

prevent

SIG

prevent

in

ex-

219.

or

heat.

and

Section 38

the organizational ma.nitenance level (operators and repairmen) are

necessari ly limited

able troubleshooting is based on

use of

cracked insulators, etc.

which of

compon

39.

caused

opporent, check os a detailed, examination of

IV.

TROUBLESHOOTING

MAINTENANCE

..

Scope

a.

The

troubleshooting

in

parts

issued,

the

senses in determining such troubles as burned-out tubes,

b.

The

following paragraphs

the components are

ent

Visual

a.

Failure of this equipment to operate properly usually will be

by

one

(1)

Improperly connecLed (2) Worn, broken, (3) Burned-out (4)

Broken wires caused by excessive vibration.

(5) Defective tu bes. . .

b.

When failure is eocoumercd and

and

to the defective stage or item, such as a tube

Inspection

or

more of tho foll

many

and

rcpnir work

scope

by

the

by

tho existing tactical

t,be

performance of the equipment

at

fault

owing faults:

bat.Lory

or

disconnecLed cords or plugs.

fuse.

of

t,hcse

the

component

AT

ORGANIZATIONAL

LEVEL

that

can be performed

t,ools,

test

equipment., a.

situn.Lion.

in

this section

and

in localizing the fault in each

cable or power lino cord plug.

the

items as is practicable before

11<.'lp

cause is not, muned1ately

parts

of

nd

Accordingl

in determining

or

Lhe

system.

replace-

and

fuse.

start

at

y,

the

.ing

If

35

possibl

garding performance

40.

help the operator to locate trou tho items to the

correct

it~ms

the sett represents given

visible and audible signs the operator should perceive wl are checked.

apply the

which the operator can make without turning in the repairs. A reference in the table to chapter 5 indicates trouble cannot be by

inoperative or if the recommended corrective measures do

resul ts,

e,

obtain information from the operator of the equipment re

at

the time trouble occurred.

Troubleshooting

a.

General

no1·mal

in

b.

Action

action

ings under which the item is to be checked.

.

The

be

checked, the co.1ditions under which the item is checke

indications and tolerances of correct operation, and the

ive measures the operator can take. To

numerical sequence.

or

Condition.

or condition column consists of various switch and cont

an

action t.

by

Using

equipment performance checklist (par. 41)

hat must

Equipment

b1e

in t.he equipmcn t.

For

some items, the information given

be taken to check the normal indication

Performance

The list

use

this list, jotlow

Fo

r other items, it

Check

in the normal indications column.

c. Normal Indications.

If

the indications are

recommendC'cl

d. Cotrective MeaS'llres. Tho corrective measures listed are tho

corrected during operation and

an experienced repairman is necessary.

troub

leshooting is necessary.

The

normal indications listed include t

not

normal, the operator should

corrective measures.

If

equi~ment

that

troubleshooting

the

set

is completely

1en

not

the it

tha

t the

list

gives

ems

yie

will

d,

th

in

rol

he

se

for

ld

e

36

41. Equipment Performance Checklist

a.

Power lline Operation.

Item

No.

Item

--

p

I Volume

R switch.

E 2

p

A

R height.

A

T

0 5

R

y

3

4

Loop

Vlhip

Power Power

s 6 Volume

T

A

control

\

antenna

switch

___________

_____________

supply line cord _________ _

adapter

control

. clockwise position.

R

T

and

on-off

__

______

__

on-off

Set

to

terclockwise position).

Swing

operating

Extend

Set

voltage

Plug

sou

Set

Action or condition

off position (maximum coun-

front

cover

of

case

position.

antenna

switch

85

on

to

be

used.

cord

into

proper

rce.

volume control

adapter

up

to

maximum

for line

line voltage

maximum

to

into

Normal Indications Corrective measures

Neon

pilot

light

is

illumi- Check fuse. Replace

nated.

light. plug.

dial

Reverse line cord

E ·

Q

u

I

p

M

E N

T

p

E

R

F

0

R

M

A

N

c

E

Item

No.

7

8

9

10

11

12

13

Item

Tone

controL ____

Band

selector switches

Tone

control switches ______

Volume

Headsets

External

controL

________

antenna.__

ground

__ _ __

______

-~

____

_______

___

________

_ _

__

Set

all

right

Press

switches, turn

Operate

----_ Turn

___

Head

_____

Connect

(For power

connect

line

___

Connect

power

power mAking connection.)

Action

tone

(normal

ea.ch

each

or

control

operation}.

of

seven

switch

condltion

switches

band

tuning

control.

_____________

to

the

selector

Normal indlcatlons

Normal

Signals

Tonal

variations

frequency

heard

in

counterclockwise _________ - _ Volume decreases

sets

plugged

into

jack

J3

_____

Speaker

tive;

becomes i

signals

headsets.

to

antenna. line

power

terminal.

operation,

cord

plug

dis-

from

I ncrea.sed

be

and

signal

sw

bands.

while ma.king connection.}

to

ground

line

cord

terminal.

operation,

plug

from

(For

disconnect

line

while

Minimum

hum

pickup.

line

response_

loudspeaker_

__________ _

______

___

nopera

heard

pickup

noise

in

on

and

Corrective measures

If

signals obtained, check voltage condition; receiver.

If

no

noticed,

(chs. 4

_

Check

4a.nd5).

-

If

headsets

check

Check

Reverse line

a.re

and

replace

tonal

variations

check

and

volume

do

jack

J3

antenna..

ground

weak

power

battery

5). cont

not

conta.ct.s.

connection.

cord

or

not

line

pack

tubes

in

a.re

switches

rol (chs.

operate,

plug.

14

15

16

Volume

Power

Tuning

s

T

0

p

switch.

line

control

cord

controL

and

on-off

__ __

________

___ ____ _

Turn

clockwise position control).

Roll

up set of

---

case will close firmly.

Rotate

terclockwise

is

at

ing

to

off

position

and

stow

jack

J3

so

tµning

control

until

low-frequency

range.

cord

that

(full

counter-

of

volume light goes

near

head-

back

cover

knob

coun-

dial

pointer

end

of

tun-

No signals

are

out.

heard.

Pilot

..

0

b. Battery Operation .

Item

No.

--

p

R

E

p A 3

R

A 4

T

0 5

R

y

1

2

Volume

switch.

Loop

Whip

Power Batteries

Item

control

antenna

line cord

________

and

on-off

__________

_____________

____________

__________

___

Action or condition

Set

to

off position

terclockwise position).

Swing

front

operating

Extend

Plug

Connect

height.

power

84

(fig. 4).

antenna

batteries

(maximum

cover of case

position.

line

cord into

to

(par

coun-

up

maximum

switch

. 13) ____

into

___

I

Normal indications

I

Corrective measures

s 6 Volume control

T

A

R

T

N"e.

switch.

For EQUIPMENT

PERFORMANCE

and

on-off

Set

volume control

clockwise

and

STOP

po.c;ition.

checklist,

soo

to

items

maximum

No. 7 tbrou11h

16

Neon

In

a above.

pilot

light

glows

____

__

Replace

dial

batteries.

light.

Replace

CHAPTER

4

THEORY

42. Block

Radio Receiver R- 520/URR designed Th

e frequency ranges are given in paragraph plete schematic diagram of this receiver. of

an

pentagrid converter which operates

(high-frequency) oscillator. is used on each of the three groups of bands ous coverage shortwave bands, and the spread bands). diagram, which shows the signal cussed

a. First

tuned r-f signal voltage, provides isolation between the oscillator section of

tube frequencies) from entering the converter.

b.

section of combination mixer and oscillator tube secti

on higher than the signal frequency on the t

in

uous coverage bands, and

This voltage is combined with the received signal

of tube

then

c.

fixed-tubed to the frequency difference between the h-f oscillator and the incoming r-f signal, and is thus amplifier occurs

d. Detector and First

i-f

amplifier is fed to detector tube V 4 for demodulation. V 4 is a

dual tube, which serves

amplifier. The detector stage ume control)

Dia

gra

m

(fig.

15)

to

receive a-m signals in the broadcast and shortwave bands.

antenna section,

in

a through e below.

R-F

amplifier tube

V2

and the antenna,

Converter.

of tube

V2

is

amplified by i-f amplifier tube

I-F

Amplifier. The i-f amplifier

in

V2

to produce a difference beat frequency of

that

operates on

the i-f amplifier.

vo

an

r-f stage which uses a 1U4 tube, and a 1L6

A different mode of tuning and tracking

Amplifier.

The

signal from the r-f amplifier

produces an h-f oscillator voltage

ltage which automatically controls the gain of the

The

Vl.

The

and

455

A-F

Amplifier.

as a detector and a first a-f (audio-frequency)

is

a portable superheterodyne receiver

4.

Figure 40

The

tuning system consists

as a combination mixer and h-f

(broadcast band, continu-

path

through the receiver, is dis-

signal

also stops unwanted signals (at im

kc lower on the four spread bands.

kc. Most of the signal amplification

also produces the ave (automatic vol-

is

fed

from the antenna to

r-f amplifier serves to increase, the

is

fed

V2. The

broadcast and the two con-

in

the mixer section

V3.

is

a high-gain circuit which is

a constant, single-frequency

The

amplified signal from the

The

to

that

455

is

a com-

block

age

the mixer

oscillator

is

455

kc

kc, which

41

...

receive1· and

to power amplifier transformer which permits the use

loudspeaker.

43.

Tuning for the receiver is provided itor required when the correct band selector button is pressed. This action

nects the stages. Where practicable, switching is simplified by shunting the

desired circuit components across the unused circuit components. Most of the unused coils are shorted to prevent any undesirnble resonant effects. types of bands

details on the receiver tuned circuits are given

through 48.

a.

kc. Tuning is provided by means of

sections for broadca switch rearranged in figure I6 to facilitate circuit discussion (pars. 44, and 46).

b.

from 2

the same gang tuning capacitor Both continuous coverage bands have similar antenna, r-f, and converter circuits. Figure I (par. 47), shows the r-f and converter stages for 4- to 8-mc operation (pushbutton

sections of

c.

Th

9.8

me (3I M),

1'7.5

to I8.I me (I6 M). Tuning is provided by means of the same ganged tuning capacitor used on the broadcast band. All four spread bands have similar antenna, r-f, and converter circuits.

Figure I8, which is used to facilitate discussion (par. 48), shows the r-f and converter stages for Figure

by regulating the bias voltage to the grids

V3.

e.

Final Audio Power Amplifier.

audio-output i;tage

V5

Tuning

in

Th

secbions

The tuning ranges of the two continuous coverage bands are

e tuning ranges of the four spread bands are from

36

Circuits

conjunction with other circuit components.

to

tune the receiver through a desired band are selected

coITect

are described

e tuning range of the broadcast band is from

A,

C, and

st

operation when BC pushbutton

actually are arranged

to

4 me and 4

SIB pressed). Figure

SIB drawn

11.6

shows the circuit with the sections of

VS

for power amplification.

is applied across

tuned circuits to the antenna, r-f, and oscillator

The

tuning methods used for the three different

E.

FiglU'e

to

in

lin

to I2 me

16

8 me, and tuning is provided by means of

7,

which is used to facilitate discussion

e.

(25

16

M operation (pushbutton

The

audio signal from

an

impedance-matching output

of

headsets (not supplied) or the

by

a three-gang variable capac-

in

a through c below. Additional

g.anged

shows the r-f and converter stages

SIA

in

line

(fig.

as used on the broadcast band.

35 show

M), 14.9 to I5.5 me (I9 M) , and

s the circuit with the

SID

of

tubes VI,

V4

The

output

The

components

in

paragraphs

540

to

tuning capacitor

is pressed. The

34),

but

are sh

9.4

SID

pressed).

drawn

in

line.

is

con-

I,600

C2,

own

45,

to

V2,

fed

of

44

42

ANT.

R-F

AMPL

VI

IU4

CONVERTER

r-MixER--, : (112)

V2

I

L-!.r_j

rLOCAL

l

ose

I (

L-..!~

H:-F-,

ILLATORI

1/2) V2

__ _J

i

I-F

AMPL

V3

IU4

DETECTOR

A-F

AMPL V4 IU5

AVCTO

R-F

AMPL

CON

VERTER

I-F

AMPL

AUDIO

OUTPUT

V5

3V4

PLATE

AND S

VOLTAGE

CRE

EN

I

I I

I

L-<"

'

HEA

SPEAKER

A

......

'"'

- \

,_

I

'<_,...

DSET

Figure 15. Radio Receiver R-520/U

RR, bloc

FILAMENT VOLTAGE

117V

AC 230 V AC 230V

DC

k diagram.

OR

O.C

POWER

SUPPLY

BATTERIES

TM

877

- 15

44.

Broadcast

(fig.

The tuned antenna circuit consists of loop antenna E2, antenna

loading

end of the loop antenna (junction of

control grid of the

the control grid of the coil the lower end of loop antenna

is

end of tuning capacitor provided by capacitor ClO. Capacitor C3, resistor ClO antenna and serve caused by 02B track

power line from a direct ground connection when operating from

power line source.

45.

Plate voltage for the r-f stage

through primary winding Screen voltage for the r-f stage is supplied directly from the low bus. Primary winding CD of coil plate load for

ganged capacitor

through capacitor

stage 02D, mounted on top of ganged tuning capacitor C20, is set to track

discussed in paragraph 59. The plate and screen voltage distribution system is discussed in paragraph system is discussed in paragraph

coil

IA

increases the tuning range of the circuit. R-f coupling from

provided by capacitor C3. Similarly, r-f coupling from the lower

form an impedance-matching network for any external long-wire

is

mounted on top of ganged tuning capacitor C2A and

at

the h-f end of the broadcast band. Capacitor

Broadcast

(fig. 16)

is

supplied through isolating resistor

at

the h-f end of the broadcast band.

Antenna Stage

16)

IA, and ganged tuning capacitor

Jl

and IA) is connected

1U4 r-f tube through capacitor C30 which isolates

1U4

r-f tube for ave action. Antenna loading

E2

to the filament of the r-f amplifier

C2A

to the filament of the r-f amplifier

to

minimize any change of loop antenna tracking

different lengths of external antennas. Trimmer capacitor

R-F

Stage

is

supplied from the high

CD

of coil

Vl. Secondary winding AB of coil

C2C.

Th

e filament of Vl

C9. Ave voltage to control the gain of the r-f

Ll

and damping resistor R3.

Ll,

in series with R3, forms the

58. The ave voltage distribution

53.

C2.A.

Rl,

Cl

Ll

is

returned to

R2.

Trimmer capacitor

The

filament circuit

The high r-f

to

and capacitor

is

set

isolates the

B+

bus

B+

is

tuned by

B-

for r-f

is

the

is

to

a

46.

Broadcast

(fig.

The combined functions of the mixer and h-f oscillator are performed by pentagrid converter and first two grids Grid 1 (pin

functions filament, mixer grid (pin 6), screen grid (pin 5), and the plate Plate voltage for the oscillator section is supplied

bus through primary winding

44

Converter

16)

act

4)

functions as the oscillator grid, while grid 2 (pin

as

the oscillator plate. The mixer section consists of the

Stage

V2,

which uses a type 1L6 tube.

a'8

a triode to comprise the oscillator section.

EF

of

coil

L2. Screen

Th

e filament

from the low

volta~e

(pin 2).

also is

3)

B+

supplied from The

screen is bypassed for

provi

ded the gain of R26 (par. 53). C9.

Paragraph

a.

The

its

operating frequency on the broadcast band is the incoming signal frequency. Section pl

ate

feedback winding Windings broadcast

600-

kc

padder

DB.

Temperature

ci

tor C2F Trimmer set

to calibrate the oscillator Coupling from winding by capacitor

· the

broadcast

_ winding

of

swjtch

in

series,

b.

The

to

the

mixer

is

app

lied through capacitor

e

ff

ectively neutralizes

pl

ate

and

Pulling

of and ve within

frequency (i-f) is transformer TI.

in

the

oscillator frequency

it

produces

rter. Mixing

the

low

by

the

combination of

the

converter stage is supplied Lluough isolating resistor

The

59

oscillator is

GH

and

band.

are

capacitor

GH

SIA, through

signal from

the

a

electron

Ganged tuning capacitor

capacitor C13,

both

C14. Windings

band.

of coil L2 is s

and

winding AC is shunted

anoth

grid

(pin 6). A portion of the r-f amplifier

mixer grid so

pentagrid

an

action

taken

B+

bus,

but

rf

by

capacitor

Cl2

and

filament is returned to B-for r-f through capacitor

contains n discussion of the

the

tuned-grid, plate-tickll'r, feedback type a.nd

and

section

AC

of coil L2 nnd coil L3 are

and

both

compensating capacitor

in

parallel with ganged tuning capacitor

C2F

is mounted

at,

the h-f end of the broadcast ba.nd.

DB

of coil L2 to tho oscilJator grid is provided

GH

and AC of coil L2 are

To

pr.went undesirable resonance effects,

hunted

er

section of swjtch

the

r-f amplifier is applied through capacitor C7

the

interelectrode capacity between the oscillator

converter, such as

to

incorre

ct

between the oscillator

stream

from

by

C8

to the oscillator plate (pin

that

shift toward the applied signal fre.quency,

i-f frequency

of the converter tube.

the

plate (pin

through dropping resistor R7.

Cl

1.

Grid leak bias is

R6. Ave voltage to control

filam<.'nt

455

EF

of coil L2 is the oscillator

DB

is the tuned-grid winding.

C2E

capacitors

Cl5

shunt

and

circuit.

kc

higher

not

used on the

is

in series wjt,h

grid winding

Lrimmer capa-

than

CZE

on

top of capacitor

capacitor

oscillator pulling is minimized.

042

by

capncitors C38

SlA.

the

1L6, is the tendency

in

the

output

and

2)

and

C2E

and

is

not

used

on

through a section

and

C14,

output

of the con-

r-f signals occurs

The

applied to the i-f

also

3)

which

difference

.

47.

Continuous Cov

(fig. 17)

The

two continuous coverage tuning ranges

and

4 to 8 me.

ganged tuning capacitor C2.

r-f

and

, , , J

1'vill

a.

coupl antenna

converter circuits· therefore onlv

be

discussed.

Antenna

ed

to

antenna

(when used) is coupled to

The

Stage

erag

e Bands

antenna,

(4-

to

coil

L5

r-f,

and

Both

tuning ranges

8-mc).

through capacitor C27,

The

ant

are

from 2 to 4

conve

rter

stages

have

t,he

telescopic whip

.enna coil L5 tlu·ough capacitor

are

similar

4- to 8-mc circuit

antenna

and

an

me

tuned

antenna

external

by

is

45

E2 Pl

~1

I

~1)

L - -

---'

I

JI

0

L4

TO

V4

PIN7

RI

2200

'

Figure 16. Broodcast band antenna, r-f amplifier,

I

and

ccnverter circuits.

TO

LOW

R7

68K

B+ I

I

TM877-16

C2S. capacitor the track pacitor the direct ground connection when operating from

r-f amplifier are sut>Plied as described stage is coupled inductively to

and tively shunted across

section of

Tuning is provided

C35A is circu

coverage oscillator coil winding of broadca C39.

pa.dder capacitor on winding of switch in impedance loading coil lator winding resistor R7. filament circuit is discussed

set

The antenna

C2A

1 U4 r-f tube

at thel

-f (low-frequency) end of the tuning range. Trimmer ca-

C3IA

in series with parasitic suppressor R24 is

h-f end of

b. R1

is coupled capacitively

to

track

it

is discussed

c.

Conv

At

the

secondary of broad

the 4-S

series,

on

by

ganged tuning capacitor C2E.

to calibrate C40A is set to calibrate at the r-f amplifier is coupled to the mixer grid (pin 06

and

amplifier is applied

(pin 3) which effectively neutralizes the interelectrode capacity

between

the

St,age

band

at

the

set

to

track

erter

band

st

oscillator coil

the same time oscillator coil winding LISB is shtlllted a.cross

me band. To

GH

of coil L2 is s SlB, through

shortwave. Oscillator

EF

of coil L2. Screen voltage is supplied through dropping

Th

also through

the

oscillator

pulling is minimized.

the

incoming signal frequency.

mixed within

cy

frequen tran

sformer

(i-f) is

Tl.

cll-cuit consists of coil LS shunted

and

trimmer

VI

is provided

tuning range. Capacitor

(4-

to

8-mc). Plate, screen, and ave voltages for

selector switch

by

1-f

end of

at

in

paragraph 59.

St,age

is selected

and winding AC is shunted

th

(4-

LISA is shunted effectively across

03

9.

another section of switch SIB. Coil L3 is a high-

e screen is bypassed for r-f

at

the

1-f

r,oil

tlu·ough capacitor C8

e electron

taken

02B.

by

the

secondary of broadcast coil

gang tuning capacitor C2C. Coil

the

h-f end of the tuning range.

to

8-mc). When the 4-S me continuous

by

section

EF

cast

oscill

Windings

prevent

hun

that

improves

in

end

of

tho h-f end of the band. The signal from

Ll

and capacitor

plate

The

oscillator frequency is 455 kc higher

stream

from the

Coupling to the control grid of

by

capacitor C30. Coil L5 is

01

isolates the chassis from

a power line source.

in

paragraph 45.

the

converter stage

capacitor 06. R-f coil L

SIB

and

capacitors C34

tuning range and trimmer capacitor

SlB

of the band selector switch,

through series capacitors

ator

coil

DB

through fixed oscillator

GH

and

AC

of coil L2 are

undesirable resonance effects,

ted by. capacito r 042 tlu:ough a section

by

capacitors

the

operation of the h-f oscil-

plate

voltage is supplied through

by

capacitor 011. T

para.graph 59. Tuning is provided

Th

e core of coil LISA, L18B is

the

4- 8

me

band

. Trimmer capacitor

6)

through capacitor

07.

A portion of

to

the oscillator

and

the mixer grid

The

oscillator and r-f signals nre

of

the

converter.

plate

(pin

2)

so

and applied to

set

by

LI

The

the

038

that

The

by

to track

r-f coil

I2

through a

and

Ll2

037

and 014,

oscillator

difference

tuning

set

to

at

the

The

r-f LI

is effec-

ClO.

is

set

filament

primary

and

not

used

he

the

r-f

plate

than

the

i-f

47

TELESCOPIC

W

ANT.

6

El

C27

470

WHIP

C'9

B-

BUS

I

1

NOTE:

J..

SWITCH SIB

I.

POSITION. I

f 2. RESISTOR VALUES

VALUES

-S~E_o.

L

SHOWN

IN

UUF

UNLESS OTHERWISE /

__

- - - _

Figure 17.

.IUF

IN

OPERATING I

l~

OHMS, CAPACITOR

--

Typical

_

_J_ _ --

continuous

I

coverage

!"

I

,

_ - _ SI 8

band

(4 to 8 me), antenna, r-J amplifier,

R26

IMEG

rfii'Mm

and

converter

circuits

.

48.

Spread

Ban

ds

(fig. 18)

The

four spread

(11.6 to

T

he

each of

will

antenna Tuning itor Th

12

me), 19 M (14.9 to 15.5 me),

antenna, r-f,

the

be

discussed.

a.

Antenna Stage

coil L7 shunted

capacitor C2A with

C32 to

provide

is circuit is coupled to the control grid of 1 through capacitor C30. Antenna coil L7 is of

the

tuning

t

hr

ough coupling capacitor When antenna the

an

external

coil is provided

chassis from direct ground connection when opera.ting from a

bands

tune

and

converter stages are similar

four spread bands

(16

M).

by

its

band

spreading over a narrow frequency range.

range.

The

antenna

telescopic whip

027

is used, coupling to the high side of the

by

capacitor

as follows: 31 M (9.4 to 9.8 me), 25 M

and

16 M (17.5 to 18.1 me).

in

operation

and

therefore only

The

antenna

the

circuit is

16

made

two series capacitors C32

trimmer, C2B, is

to the high side of

028.

shunted

U4

r-f amplifier tube

set

to

antenna

across capac-

track

at

is connected

antenna

Capacitor

01

powerline source.

b.

R-F

Stage (16

amplifier

are

supplied as described consists of r-f coil L14 The

coil is

set

tuned

by

ganged capacitor

coupled to the control grid of converter tube

06

and

the

high side of r-f coil L14 is tied to this same capacitor C36. spread-band operation. capacitors

C34

impedance to shortwave frequencies,

to

the shortwave frequencies, control grid of charge.

c.

The

filament circuit is discussed

Converter Stage

(1)

When

band

verter

to

the

to operate

the

possibilit,y of h-f oscillator shift which

ave

voltage is applied to a converter stage. Oscillator

voltage is supplied through winding voltage js supplied through dropping resi screen is bypassed for

circuit is discussed in

M).

to

track

Plate, screen,

in

series with isolating capacitors C34

at

the center of the

CZC.

and

in

paragraph 45.

band.

The

plate of

ave voltages for the

The

the

1 U4 r-f

V2

through capacitor

point

Lll

is an r-f choke coil which acts as a fixed grid

It

is

shunted

and

C36. Since

it

and

the

1L6 converter tube from accumulating

(16

M).

the

16

M spread band is selected

across r-f coil

has a low d-c resistance

it

creates a high-loading effect

its

low d-c resistance prevents

in

paragraph

by

section

selector switch, no ave voltage is applied

stage, since the mixer grid (pin

filament through coil

at

the

point

Lll.

of maximum sensitivity

6)

is returned directly

This allows the converter

might

EF

of coil L2. Screen

stor R7.

rf

by

capacitor

paragraph

59.

011.

circuit is

Ll4

59.

to

and

result when

The

M circuit

up

and

C33.

the center

coil L7.

isolates

r-f circuit

and

C36.

not

tube

through

and

a high

the

any

grid

SID

of the

the con-

avoids

plate

The

filament

on

of

VI

r-f

is

on

361'.'iOl

1- 5

5-

4

49

UI

0

TO

LOW

8+

I

/

I

BUS

/

8-

.I

C9

UF

i----

-

-+-=-_,,.-

I

-

--lf---_.

I I

/

NOTES

I I .

1

2.

I VALUE!.

L---~-ECl~IED.

: /

SWTTQi

SID

9iOWtf

IN

RESISTOR VALUES IN OHMS, CAPACITOR/

IN

UUF UNLESS OTHERWISE I

___________

OPERATING

F'l.gure 18.

POSI~

Typical

.

/ i

_J_

____________

spread

band

(16

M)

___

;'

;_'

___

antenna,

I

..1,

!l~~6

r-f

amplifier,

I

.. , _____________

and

converter circuil.8.

C42

l20

TO

LOW

i!

L20

8+

;'

._/

Tii1871"-18

(2)

The

basic oscillator circuit is a modified tuned-grid, plate-

ticklor, feedback type. Oscillator shortwave secondary winding shunted across broadcast padder capacitors grid is provided

bination

capacitor

over

loading coil

on shortwave. The broadcast oscillator

is

not

broadcast primary winding

oscillator section. Oscillator coil L20 me. The signal from mixer grid (pin

r-f amplifier

oscillator

interelectrode capacity between the oscillator plate and

mixer grid so

spread bands, the oscillator frequency is

the signals are mixed within the electron The difference frequency and

of

capacitors 014, C15, 038, C42, and gang tuning

C2E with trimmer C2F results in band spreading

a narrow frequency range. Coil L3

left

in

the

affect circuit operation. On shortwave frequencies,

plate (pin 3) which effectively neutralizes the

incoming signal frequency. The oscillator and r-f

1s

applied

014

by

that

improves the operation

circuit to simplify band switching and does

6)

through capacitor C6. A portion

output

that

to

i-f transformer

coil

and 042. Coupling to the oscillator

capacitor 012. The series shunt com-

EF

the

is

applied through capacitor C8 to the

oscillator pulling

(i-f)

coil

L20 is in series with

AO

of

coil

L2. Both

secondary BD through fixed

is

a high-impedance

of

the h-f oscillator

coil

secondary

acts as a plate choke for the

is

set

to track

r-f amplifier

is taken from the plate (pin

Tl.

is

minimized.

455

stream

coupled to the

of

coils

a.re

BD

at

17

.8

of

the

On

the

kc lower

the converter.

than

2)

49. 1-F Amp

lif

ier

(fig. 19)

The

i-f amplifier consists

amplifier

core tuned.

across the primary and secondary windings of used for resonating the input and pacitor of isolation resistor R12, provides neutralize

plate.

i-f amplifier can

oscillation. the transformer T2. The i-f signal is coupled to t.he tuned circuit consisting of the secondary of transformer T2 and capacitor

then is applied to of ave voltages.

V3

uses a 1U4 tube. I-f transformers

Capacitors C16,

Cl8

does

not

provide complete bypassing for the screen grid

the

i-f amplifier.

the

effect

of

With

an optimum value for capacitor

be

increased considerably without danger

The

455-kc i-f

tuned circuit consisting

the

diode section

of

a single stage tuned to

Tl

Cl

7,

Cl

9,

and C20A are

Tl

ouLpuL

Inst

ead, capacitor Cl8,

a feedback

the capacity between the signal griu and the

output

from the plate

of

capacitor

of

V 4 for detection and development

circuits to

in

path

to the screen grid to

C18,

Cl9

and the primary

455

kc. I-f

and T2 are iron-

fixed

capacitors

and T2 and are

455

kc. Ca-

conjunction with

the gain

of

V3

of

self-

is applied to

C20A,

and

the

of

51

FROM

PLATE

TO

V2

HIGH

B+

TO

AVC

NOT~

:ES

ISTOR

IN

UUF UNLESS OTHER

I·F

AMPL

V3

IU4

TO

PIN I

VALUES

V!!

IN

OHMS,CAPACITOR

WISE SPEC

TO

CO

IFIED.

TO DIODE

VOLUME

NTROL

VALUES

TM877·

V4'

R17

19

Figure 19.

1-f

amplifier.

50. Detector-Amplifier

(fig. 20)

d

The

Detector-amplifier stage

i-f signal from the secondary of i-f transformer

the diode plate and one side of tho filament.

appears across diode load resistors R Rl7. contro

Tho audio signal

· d f h d · G · d load resis

l

gn

o t e pento e amplifier section.

R18 is high enough

V4.

uses a 1U5 djode pen.to

16

and

R32 and

is

fed through coupling capacitor

in

value to provide contact

e.

T2

is

apph~

The

.volU1D

ri

po

ten trnl

au

class A operation. Screen voltage is supplied from the low l'fi d source through decoupling network R21 and 022.

audio.developed across capacitor

bypasses

voltage for dropping

024

to the gm! of tho audio-output stage.

the

plate of the amplifier for radio frequ<'ncies.

the

pentode amplifier section is supplied through

resis~or

025. '!'he action

51. Audio

Output

~late

load resistor R22 is

R4. Additional filtering is provided

of the ave circuit is discussed in

The

fed

through?°?

Oap_acito

paragraph

(fig. 20)

The

audio signal from

the

3V4

(V5~

of

a.u~io-output

voltage is supplied directly from the high is provided from output

transformer T3.

the

high

the

detector-amplifier is applied to the grid

stage across grid

B+

bus through

Ca.pa.cit

.or

0450

n+

resi

stor

bus.

Plate

the

primary

bypasses

R20. Screen

the

455-kc

. b

tween

e tput

10

Ot~trol

°

c~

the

21

0

. tor

. b'

ins

a.mp

for

B+

1

U.:

CZ~

Pl te

a.

volt~ge

by

capacitor

53.

voltage also

winding of

plate

and

52

T2

DET·AMPL

V4

IU5

4

C23

51

AUDIO

OUTPUT

V5

3V4

screen volt

obtain d

{par.

r:~

· Y ietu1~nmg

~t~·

f

ormer T3

closed

contacts

is dis jack

;,nnected

C22

CZI

.01

UF

TO

TONE

CONTROL

NOT

E:

5

a~Ek

0R

8T8

F'igure

to.

b

ng~

sour~e

.02

UF

B-

VALUES

0

THERW

Detector-amplifier and audio output

for audio frequencies.

BUS

R21

4.7

MEG

S2B

IN OHMS_,

ISE

SPEC

ll"IEO

R20 to a point on

~apn~itor

0

scillat.tons in transformer

· ·

is coupled to loudspeaker

C26 bypasses undesirable noise frequeucies and

r · k .

0

Jae J3.

For

head

automatically when

TO

VI

PINS 1,5

LOW

B+

R4

3300

CAPACITOR VALUES IN

The

the

series filament circuit

T3

The

secondary of trnns-

LSl

through the normally

set

operation, the loudspeaker

the

headset plug is inserted in

TO

CONTROL S20

TO HIG

B+

UUF

stages.

correct grid bias is

TONE

H

TM877-20

52.

Tone

Control Circuit

(fig. 21)

a.

The

f eedb k ion o the tone control crrcwt epen s on an mverse res·

IS

f

ormer

.

~~~stors

. ·

r~sistor-capacitor

operat· f · · d d ·

tac voltage

Ol'-Cap"c1'

T3

· e tone control resistor-capacitor network consists of

R16,

The

thnt

t . . d' t t t

""

or

Th

Rly,

function

is fed back to the volume control through a

network from the tertiary win mg on ou pu rans-

. .

R32, R33, R34, R35, and

of

the four-tone control switch

cap~citors

es

.C47,

is to

network frequency characteristic which results

048, and

vary

the

in

c lan?e of a-f response. For example, when BASS tone control switch S2B.1s open, only the higher audio frequencies audio because they effect. Since capacitor

frequencies are effectively suppressed in the

a.re

fed back

out

of phase; this results in a bass boost

C48

has a higher reacts.nee to

a.re

fed back.

output

the

low audio

The

circuit,

high

53

a

OET-AMPL

V4

IU5

AUDIO

OUTPUT

V5

3V4

____

2

,

T2

frequencies, the low frequencies nre boosted effectively switch

shorted

7 I

---.,

NOTES L

2.

I

~I

____

J

:

TONE

CONTROL RESPONSE THE

RESISTOR

UNLESS OTHERWISE SPECIFIED.

RIGHT

(ALL

ON

VALUES

B-

BUS

SWITCH

FOUR

FRONT

RIB

15

MEG

B-

BUS

S2B

lBASSl

POSITIONS BUTTONS

PANEL).

IN

OHMS. CAPACITOR VALUES

Figure

131.

157

TO

HIGH

.02UF

C4J

S2C

lvo1cEI

SHOWN

OF

SWITCH

Tone

control

B+

(ALTfil

FOR

52

circuit.

S2B is open. When switch S2B is closed,

out

and eliminates the bnss boost; this

520

NORM~

SET

IN

uuF

capa~

results

J3

BASS

~beD

048

it~r

creased

lD

Jll

treble response. . ueoe-

· R33 · l" · ·

R

b

. es1stor is a urutmg resistor and is used to

ration

amplitude of the audio frequencies fed crrcmt. Wlth reduced effectively. Capacitor

quencies around

at

the very low audio frequencies. Resistor

back

Lo

. . Wh th ALTO · · I

. l ' ' ' 1 boos

the

C49

pn.sses boost when age. When sistor

and

middle frequencies. frequencies

lower audio frequencies is been boosted

en

e

sw1tcb

feedbac { vohage and the

Rl

. h

b b

t e

1g

swi~ch

s~vitch

~34;

this

caus~

is

reduce Y

in

relation to

6 when

S2C

TREBLE

f . a ass

er requenc1es more readily and produces

i~

closed because of the inverse f eedbn.ck "'

1s

closed! capacitor c

a greater

The

..

tl

db

ns

· ·

not

S2D is open R35 is

output

C47

bypasses

switch S2A is closed.

i~verse

gam

feedback voltage

n.t

these

inverse f eedbn.ck. Since

ff

d ·

a ecte , the low audio frequencies .

the

middle and higher audio frequ encies.

the

levol of

the

9

is

4

hiah

o .

vent

pre

R35

l6e

.

•ts

liW' otrol

volutn°. co

ed

Pac

the

in

ow

higher audio

Capa

shunted

and

across j b

_of

middle

the

ga1n a

the

·jes

50

1

t

. I

ci~or

b

0

b

au h

tt

b~e

is

·s

1

·e-

lt

;

.6_

1

lo

e

54

53.

Ave

System

(fig.

22)

a.

The ave system controls the gain stages. tinuous for

to

Figure

coverage bands.

22

shows the ave network for the broadcast and con-

On

spread-band operation, the ave circuit the r-f and i-f stages remains the same the converter stage.

The

converter control grid is connected

of

the r-

f,

converter, and i-f

but

no ave voltage is applied

through the band selector switch from grid resistor R26 to r-f choke coil

Lll

(fig.

18). Under these conditions,

operates

which

voltages are obtained from tween to develop

for

voltage

n~

nux~r

the i-f amplifier control grid load

and shunted branch

?-ivid~r

isomt1on

~t

mg for the ave system is provided

at

the point of maximum sensitivity.

b.

Resistors R16,

Rl7,

and R32 form the diode load circuit across

the ave voltage is developed. Three different levels

a voltage-divider network connected be-

the diode load circuit and different points of the filament circuit

the

correct level

of

ave

volt11.ge

each stage.

c.

To prevent r-f overload and distortion, the greatest portion

is

fed back to tho control grid

xt

greatest portion

tube

V21 and the smallest portion

d.

The maximum amount

is

fed back to the control grid of

R15

through isolation resistor R2. Resistors

by

resistor R9 through

is

in

series with resistor R13 to the diode load. This shunt

of

ave voltage is fed back to the control grid

of

V3.

of

ave voltage developed across the diode

part

network feeds ave voltage to the control grid

resistor R26. From the junction

portion of ave voltage is fed back to the control grid of

by

capacitors

1L6

converter tube

of

and correct operating bias

of

r-f amplifier tube Vl. The

of

ave voltage is fed back

Vl

from the junction

Rl4

of

the filament circuit. This

of

R14 and RlO the small-

of

and RlO are

V2

through

V3.

04,

043,

s.nd

044.

V2

ave

of

ave

of to

Rl9

Filter-

54.

Bias

System

(fig.

22)

a.

';l'he.avc and bias voltages for the receiver are tied together in a combmat1on bridge network to supply the proper tube. zero

Th

e common

v:oltage.

B-

bus

of

the receiver is used .as the point of

Bias voltage for the various tubes is provided

returnmg the control grid to the appropriate point

vol.tage

divider formed by the series tube filaments_ and the ave

bi~

voltage to each

in

the complex

by

resistor network. Filament and bias voltage are derived from the

8.4-volt d-c filament supply

b.

Ave

voltage is developed across diode load resistors

an~

R32, when

an

i-f signal is fed into the

(po.r. 59).

T2

secondary winding.

RI6, Rl7,

T~e

resistance network proportions the ave voltage to each control grid. Ave action reduces the

go.in

of the r-f converter

and

i-f stage and

55

prevents overload and distortion on strong input signal

o.

potential of -

The control grid to resistance networks between the diode plate and the various grids.

c.

Because the filame along the physical length of the filament, the center of the is used filament-center

the tube occupi

voltage of

switched to r-f choke own

as

a reference point when measuring the grid bias, EG.

d.

The diff eren

is

the operating grid bias, EG,

e.

On spread-band operation, no a

V2

(par.

filament

f. The grid bias on

connecting the grid d-c return through resistor R20 to the

of

the 1U4 is 1.4 volts positive with respect to B filament

B-.

of the operation for this

volts

of the

the voltage

The contact bias across

fil

~me?t

gr1d in

55.

Power

S3A-S3B S4 adapter

chassis). Adapter

located on the

t e

h

when the power plug is inserted S3A-S3B, which is mounted on application of power to the radio set. e

and B + circuits to the receiver

9-volt d-c sow·ce for the series

~nter

This results m

3V

4 power-amplifier tube which

o~

the control grid

mterna~

center~to-

bias, EG, is therefore

which the remainder of the tubes · . gure. s

Power Control Circuit

(fig.

for

Zl

B+

and filament circuits from e spea er, c

.25

volt is developed across diode lo

B-

voltage of each tube is determined by

nt

voltage on direct heater-type tubes

to

B-

voltage is determined by the electrical

es

in the series co

between the control grid and filament

48). 'l'he grid return which normally goes coil

(fig.

18).

the 3V4

r-f

and

1U5

is

a~proxima.tel

an

t~e

~ntact

e":1stmg

24). Radio Set R-520/URR . •t

fus

l'~hich

chll.$sis

bias created by normal filame

b

etwe~

resIBtor Rl8

B

- voltage is

e

Fl

is piugg:x;ial resistor

Zl

is shown

and to

. e

:6.la.mont

LU

and returns to the negative end

powor-ampli.fier tube is obtained

detector-ampli1ier

y

7.0 volts de positive with respect

operating bins

of

pentode.

?f

the 1

U5

n

the center of the 1 US

-1

7 volts Fi

th is applied through

:C~r:nan~ntly

th

in

fila.m

circuit.

of

each tube. .

ve

is applied to tho control

.filam

ents. This

-.

The 3V4

EG

of

-5

is

normal for class A

Tho operating bias

det,ector-ampli:fier tube is

·

1

s approxunate y - .

o.

volt. The resultant operatwg

7

receive

mo.tically

rear of th k

e~terna

6

t~

Th

ent

.

22

theu

operatmg '

RT!

, and power

into J2

in

figure 23.

l

power to

socket of switch $4. Switc

~olu.me

0

re~eiver

string and a 90- to 105-volt

control, controls

co~p

l

etes

requires

s.

ad

resistor

power-amplilier

.6

vo

lts

on the

EG

nt

emission

filament and B- ·

volt and the

1

h the manner

ow

~

on

the

SWitch

hnnD'es

~

battery

both

the

an

Norma

lly,

R16.

the

control

varies

.filament

The

position

center

gr1_d

to

1unct1on

18

R26

.

of

its

.by

~unct~on

~o

gr~d

audio

of I.7

~be

sum plus

bias EG.

hes

0

sWI

su~p

l

y

1

~ece

;~

h,

bot

po~e~

th~

fila.men

8.4- to

56

TO

a-Bus

DET-AMPL

R-F

AMPL

CONVERTER

I-F

AMPL

AUDIO OUTPUT

V4

VI V2

V3

V5

DET-AMPI..

V4

IU5

IU4

IL6

IU4 3V4

R-F

VOLTAGES

FILAMENT

CENTER RETURN

.7

v

2.1 v

3.5

4.9V

7.0

GRID

-1.ov l.56V

v

2.75V

4.30V

l.40V

AMP!..

VI

IU4

EG

-l.7V

-

.54V

-

.75V

-

.60V

-5.60V

CONVERTER

V2 IL6

NOTES:

I.

RESISTOR VALUES ARE IN OHMS UNLESS OTHERWISE SPECIFIED.

2.

ALJ..

VOLTAGES

CONDITION.

3.

FILAMENT ARE

4. OPERATING GRID BIAS 'EG' IS THE DIFFERENCE BETWEEN THE Fl

LAMENT

AGE

5.IN

BAND SPREAD OPERATION

AV

C VOLTAGE IS APPLIED

CENTER VOLTAGES AND

REFERRED

CENTER VOLTAGE AND THE

FOR

EACH TUBE.

I-FAMPL

ARE

CALCULATED

TO

B-

V3

IU4

VALUES UNDER

BUS.

GRID

LJ@(![MJl25MJ(]IMJNO

TO

V2.

AUOIO OUTPUT

V5

3V4

NO-SIGNAL

RETURN VOLTAGES

GRID

RETURN VOLT-

Figure 22. Radio

Rece1·ver

R-520

/ URR,

ave

and

Irias

system.

S5

K

R38B

620

NOTE: THODE TERMI

LETTER K

Figure t8. Power supply adapter

d-e source for the B + lme.

tials whether the

power line sow·ce. section A of switch 83 connects one side

bus, whilo section B completes the B + crrcw

R36. With •witch 84 sot for battery

connects the grounded negative terminal of the .

B-

bus, while section B completes the

terminal of the B battery.

set

is

With

CR2

AT

CR2 INDICATES

. , . ·

~he

powe1

operatmg from

switch

84.

circ .

batteiy

set

o!

operat~nitcrY

B+

CA

TM

877

Zt.

ui

t

for

p~wer

th~

P brougb fuse f

t.

crrc

. these

supp}JeS

or

from an ration,

wer

line to

t section

'\ii

t

to

56. External Power Source

(figs.

24

and

25) .

a.

Selenium rectifiers CR1 and

de. Rectliier CR2, which is locatsd in power functions only when operation

The

d-c

output

through

to capacitor 045C and the high

voltage to

B+

is also applied th.rough resistor R27 C45A,

de to tho filament strmg through

resistor

the receiver the tube filaments ;!{-ampere rating and protects the power su.pply from

the

which discharges capacitor 045A when the power is

~urge

bus. 1'he d-c output.voltage

RTI,

RTI

B+

and filonient .circuits. Res;,to,

voltage from the cathode of rectifier ·esistor R

limiting resistor R27,

•lower

and

value

•nd

and

C4~B.

is

in

senes

tendds

~rhe

WJ.t~

t?tmain~a~

esp1

e var1at1ons in line

CR2

change

is

from • 230-volt

the

a-o

supp

-

0

1

0

fuso

FI,

and

filter;

B+

bus. ResisLor

•PPlies

it

to capacitor

from

the cathode of

to

the filter circuit

output of the filter supplies Tberrnal

Rao

•nd

•section

r~s1stor

R3o

to

a constant current

"Voltage.

R2s

02

of

the

:filame~t

flow-Jog

Fuse

is

• bleeder

turned

NAL

_

23

ten-

po

external

line

opeh

B-

tF~

and

sa

A.

:

the

system t

the

0

linadapter

Y.

d-c

~

1

Rand

ctifier

.

5

10

~o

$4. circuit

ov-erl~

"tivs

posi

voltage to

soUJ

is opplie

droP• th

the

loW'

OR!

nsisting

4

vo

8

through

Fl

has a

ad in

·stor

~;

1

~l,

·':i

.

6

3

19

oJ

lts

of

58

b.

Power supply adapter

J2

at

the rear of the chassis, consists resistor R38A-

of

a three-position switch, SS; a selenium rectifier, CR2; and

R3

8B·

Zl,

when plugged into receptacle connector

is

in series with the power line.

(fig.

23). The complete assembly

is

housed

It in

a perforated metal can. Receptacle J2 is a closed circuit-type connector. Therefore,

if

power supply adapter

Zl

is removed, the

receiver may be operated from a 110-volt a-c or d-c power source. When

switch is

shorted

When

switch

A and B, and selenium rectifier CR2 are placed in series

~ower

line m the R38B

and selenium rectifier

capacitor

t?tal current drawn through the line is greater t1on

than on 230-volt d-c operation. Shorting-out resistor R38A compensates for the power supply adapter

SS

is in the

out

and the power line is connected directly to the receiver.

8S

is in the

to

lower the voltage to

220

V.

AC

.position, resistor

04SA draws

tho

110

V.

AC-DC position, plug connector P2

220

V.

DC position, resistor R38, sections

110

volts de. When

R38A

OR2

in.series with the line. Since filter

an

appreciable amount of ripple current, the

additional voltage drop

and maintains the correct line voltage to

w.ith

switch

is shorted out, leaving

on

230-volt a-c

that

would

occw-

8S

O{>era-

through

the

is

the set.

Note.

The

receiver will

cord plug is reversed; however, electrolytic capacitor C45A,

harmed by reversed currents ·because selenium rectifiers high

back resistance.

not

operate on de if the polarity of

the

B,

and C will

CRl

and CR2 have a

power, line

not

be

57

. Battery Power Sou

(fig. 24)

a.

For battery operation, a B supply voltage supply voltage

The.

bat

tery supply voltages are fed to the receiver thr?ugh. both

sections

of the B battery is connected to the positive side connection boosts the effective B+ voltage by the a.mount

supply voltage socket switch

may

not make or break simultaneously.

close

before the

capacitor of

S3A·..S3B.

surge

of

charging current and thus

b.

Resistor

to

chassi

s,

When the receiver t?e

chassis through switches

of

s\vitch 83, and through switch 84. The negative side

(9

S4

0450 tlu-ough

When this occurs, resistor R37

R29

forms

rce

o~

90

volts and

~n

9 volts are required for operation of the receiver.

of

the

A.

battery. This

of

the A

volts). When the power line

for

battery operation, all the

If

the

sWltch

B+

p~ug

is inserted into

contacts

and

A+ conta

of

A-contact, the B battery will charge electrolytic

the tube filaments and

pr~vent

which' is connected from the B- bus

~

high-impedance path to the external. power line.

is

operating on batteries, the B

S3A

and 84. Capacitor 046

~he

~l~sed

will hnut

co~t~~ts

the initial

filament bw-nouts. .

of

the receiver

~

bus

is

sh?r~~

m~im

signal and noise pickup from the power line when the receiver opera.ting from

an

external power line.

A

~f

84

cts

to

1z~s

is

59

58. Plate and

(fig. 24)

Plate

nnd screen voltage for the receiver is supplied either

batteries and is present ies,

90

volts is applied to operating from the power line, bus through S3B.

supplied through drnpping resistor R4

a.

The high B + bus feeds voltage

Va

(the 1 U4 i-f amplifier) through dropping resistor RI2.

feeds voltage to the plate of

transformer of r-f coil of transformer T2, to the plate of

former

b.

converter tube

feeds voltage to the screen grid of

~he

directly, voltage bus Capacitor

voltage

LI,

'f3

The low

screen grid of r-f tube

and

~hrough.

al~o

is supplied to the plate of

025

that

Screen

or·

from the power line through the rectifier-filter

at

switch S3B (par. 55). When operating from

TI,

to

to the plate of

and

to

the

B+

V2

the screen grid of detector-amplifier tube

dropping resistor R21. Voltage frorn the low B+

is a filter for the low

may

be present nL

Voltage

The

low B+ A bus (approxin;late

the

plate of

screen of

bus feeds voltn.ge

through winding EF of oscillator coil L2.

VI

Distribution

t,he

high

B+

bus through S3B.

105

volts is applied to the high

and

is filtered

to

the plate

V2

through the primary winding.

VI

through resistor R3

Va

through resistor R12 and the primary

V5

through the primary

V5.

to

the oscillator anode grid of

V2

through droppfog resistor

receives voltage from tho low

V4

through plate load resistor

B+

bus

and

eliminates any

that

point.

by

and

from

circuits,

batter-

ly

80

volts)

capacitor

screen

the

of

grid

It

prllllar.Y

It

B+

V4

receives

t11e

When

Bt

is

C25.

of

a.l~o

of

i-f

trans-

116

also R7.

.bus

RZZ.

}iuin

59.

Filament

(fig. 25)

a.

Radio Receiver R 520/URR B

50-ma (milliampere) co

nnected across the

power line circuit operation ge source m a series

down to 8.4 volts d thr

a.nd

Rao. On

plied across the

d circuit. Durin

an screen grid currents of

filament and add to the

current accumulates toward tl flowing through the filament. This

pr

event this extra current

resi~tors

Resistor R23 is placed across half output tube because most of the cumulates near the negative end

shunted across the filaments of v

relatively heavy plate current for the av4'

60

Circuit

bat~

filam7n~P?rat~on,

R8, R5,

fil

v::nt-type

'the

ough

ad

curre~~

fro~e

Rll,

and R2a

uses fow· 1.4-volt

tu.bes.

l05-volt d-c rectifier

~hermal

resistor

9 volts from the A

fil

·

~ent-type

bneg~tive

ui·nm~

7~h

0

1

(~na~

and

2

The

tube filaments

RTI

g norma operation, b

out

mcorporated

e filament of the aV4 audr0-

and

Va

1

tube pass through t .

end

of

the filament.

the

filaments,

s~reen

~=JSto:S

pect1

output tube around the

vely, to s

and

one

2.

-vo

arra.nge~ent.

output

and

grid

R5

IS

resistors R

battery

.

sh':1nt

in

the c1rco:t· current

and

hunt

droppe

a.re

the plate

Rll

the

Jt

~

~n

d

27

ap-

6

.To

~g

ac-

a.re

C2'

.OSUF

R21

4.TMEG

To e-eus

DET-AMPL

C25

12UF

,...-..,

._

_

_.

V4

IU5

R-F

AMPL

VI

IU4

R22

I

MEG

T

LOW

B+

BUS

eov oc

CONVERTER

V2

IL6

R4

3,300

TORTI

PRI

1-F

AMPL

V3

IU4

1,5

Tl

Rl2

..

HIGH

T2

PRI

B+

AUDIO

SUS

OUTPUT

vs

3V4

TO

FIL

VOLTAGE

SOURCE

POWER SOURCE

llTVAC

230V

I.

2.IN

3.

4.

NOTES:

SWITCH

S4

SHOWN

FOR

POWER

BATTERY

CONTACTS OF SWITCH

TO

THE

LETTErt K AT

CATHOOE UHLESS OTHERWISE SHOWN,

RESISTORS

IN

LINE oPf.RATION.

OP.ERATIOH,SLIOING

RIGHT.

CRI

INOICATES

TERMINAL.

ARE

IN OHMS.

OR

AC

DC

POSITION

54

MOVE

..-4~1~-l-~

oe

CRI

C46

.OSUF

Figure

105VOC

I

s4

. Power

R27

130

97V

DC

PART OF CHANGEOVER

,--

I

R28

UOK

I

A

supply

_S:!_l!EH_S__! ____

a- aus

circuit.

/.

.J

.

8

90VOC

c

TIUTT-41

OET-

V4

1·u5

AMP

2

1:-F

R-F

L

AMPL

CONVERTER

V2 IL

6

2

AMPL

V3 IU4

2

AUDIO OUTPUT

V5

3V4

2

INSERT

HERE

OPERATION

POWER SOURCE

117V

230V 230V

AC

PLUG

FOR

BATTERY

I.

UNLESS

RESISTORS

2.

SWITCH

FOR POWER

TO B-BUS

POWER

ADAPTER I I

RECErP_r

AC

OR

0C

OC

AC

OTHERWISE SHOWN,

ARE

S4

SHOWN

LINE

l.

4V

RB

150

C9

.IUF

SUPPLY

r---1

_

Ac_L~E..._~•o

L-O-~'~~C-R~11t--K,.,,.,,,..,.,,....,..~1/3~0,..,._.~3

l

___

J

Ji!

C46

.

OSUF

r-------------

1

I

1

NOTES:

3.

IN

OHMS.

IN

POSITION

OPERATION

CONTACTS 1'0

4.

.

LET1'ER K AT CA1'H00E

cs

~-OIUF

IOSVDC

PART OF VOLUME

CONTROL

OFF SWIT

ON ·

BATTERY

OF

1'HE

RIGHT

TERM

Fig1tr~

OPERATION,

2.8V

R27

C45

60UF

CH

SWITCH

. CRI

INAL.

~!L

RS

100

TO

HIGH

Fl

-

101s"--'A~M

-

P~_.~~"'"-rv'Cl\.-+

97VDC

PART

OF

- - - -

Al

I

~

B·BUS

SLIDING

S4 MOVE

INDICA1'ES

CHANGEOVER

~W_!°IS'i

Fil.a.nient circuit.

B+

2

~~--

4.

RTI

2V

Rll

120

C4:1

20UF

...

-

~~~---4

47V

A,

I

&J

R30

~

-A6,~80A.~

DC

____

0,

C4:1

1

200

J

UF-

5.6V R23

270

~

J

I

R29 330K

8.4V

.J

9V

-=.

filaments

of

Filament r-f bypassing for the detector-amplifier

stages

b.

of

V2

and

V 4 and

Vl

is

provided

because their plate

Thermal resistor

V3.

by

capacitors

RTl

One resistor, RS,

and

screen grid currents are small.

05

and

09.

is

a self-regulating resistor

is

used across the filaments

and r-f amplifier

that

helps to drop the 105-volt d-c power supply voltage down to the required 8.4 vo

lts

de.

Its

internal resistance varies from with power-line. voltage variations of 50-ma

current in the filament circuit is maintained. Capacitor C45D is

connected from pin 1 of

V5

to the

90

B-

600

ohms

to

1,300

ohms

volts to

127

volts; a constant

bus. Thus, any audio voltage present in the output tube filament is prevented from entering and modulating · the other tube filament circuits.

63

CHAPTER

5

FIELD

•·

•-

This

HO.,;,

repair

that

limited only

repairman.

Section

I.

can be performed

MAINTENANC

chapter

by

TROUBLESHOOTING

the

contains

tools

information

by

and

test

• I . field

units

oqu1pme11t ava1

E

. f

or

.1av111g

AT

fi

INSTRUCTIC:~~

Id

maintenance.

e . •en" nee

mam.

'!able

FIELD

.. . I r

and

by

AINTENANCE

M

mountor

. . it ·s

respons1b1l

the

sk1l

o

LEVEL

ly

are

Wa

rnin

g:

The

voltages present enough to produce shock, dangerous to life. When working

P

reser.t it is a good practice to place the equipmepf 0 perspiration

surface first, particularly 1f the s or water.

60.

sectionalize the

major component

the set.

tracing the fault to the defective part

condition. Some faults such as burned-out resJStors, shorted transformers often can

The ma

and

tion of poisonous fumes and the deposit of poisonous .8 strong.

compounds. Provide adequate ventilation immediately. Avoid inhaling e

and

b I

e ow

procedu1e should be followed

s~rv1cmg

Fu·st,

the trouble

voltage, resistance, and continuity

cedure is summarized as follows: . to

, . k' . t .

Do

not

let the rncoi'1or touch

Troubleshooting

a.

General.

jority of faults, however,

The

second step is to localize the

Procedur

first

fa.ult. Sect1onahzation means traclllg 1 opera.tton

or

circuit responsible for the

1·e8istances.

Warning: The failure of selenium rectifiers can

If

a rectifier burns

do

not handle

b.

Component

'd

· · I · h {Iect1ve,

a~

m

· ·

Pl'Oce

trouble should be locahzod to

may

(1)

VU'Ual

locate any visible

the repairman frequently

mine the stage

is

valuable

the

damaged

Sectionalization. and Localization.

1so

atmg t e

d h Id 1

ures s be isolated within

ou

inspection.

in

a.voiding

and under certain: t with

es

st~p

in. ser:icing

be

rectifier

sou~·co

in

c~use

The

trouble. Through this inspection

in

which the trouble exists.

· th power

ill

e . conditions may e

on

the

e~wpme:

mis

\Ve

damp

oi

other

a.

defec~ive

a.bnorm~·zation

fa.ult:

Loca

respons1~1e

located

must

out

of trouble.

the order given. Rernern · er. no

that

measurements.

purpose of visual inspection is

may

additiona

by

sight,

srn\

be localized

or

a.res

until

it

furt

her damage

a.

single stage

stage or circuit

discover the trouble

l dama

over,

has

To

by

result

the

cooled.

ge

P

sup

n

an

rom t

t.s

or equipmen ·

se

. dio set

t~~

fault

~be

for

-f

arcing, and

~

nd bearing.

~no

1

c

ec

. the

J.Jl

o~or

The

tes~

be

e ber that

to.

t

~

or

1

c1l'CUlt.

by

app~·oplla

The

service pro

This

inspec~ion

to

the

hig

voltages

insulated

is

~

the

means

abnormal

voltages

li

bero.-

elenium

~~

fumes

listed

the

rece1v

'flten

,.

te

a.lone,

or

de~r

receiver

y •

the

.h

b

to

o(

_

64

that might occur through improper servicing methods

39).

(par.

(2)

Input

resislalnce

66)

prevent further damage to the receiver if o

exists.

the

(3)

Operational

because In

Since this test gives an indication of tbe condition of

fi

lter circuits, its function

it

many instances,

exact nature of the fault.

fully, all symptoms must be interpreted

measure

ments.

These measurements (par.

short

is

more than prevenLive.

test.

The

operaLional

tesL

(par.

67)

is

frequently indicates the general location

Lhe

information gained

In

order to utilize this information

will

determine the

in

relation to one

important of

another.

(4)

TrO'Ubleshooting

charts (par.

(5)

Signal

substitution. The principal advantage of signal sub-

stit

ution (pars.

repairman to localize

chart.

68)

70

The

trouble symptoms listed in these

will aid greatly in localizing trouble.

through

73)

is

that

it

usually enables the

a trouble accurately and quickly to a

given stage when the general location of the trouble

immediately evident from the tests above.

(6)

Stage

gain and sensitivity

used to localize obscure,

(7)

Intermittents.

mittents should

trouble set. It b conditions.

may

be

is

possible

ut

in the installation, or

In

all these tests, the possibility of inter-

not

made

this event, test the installation, it possible.

chart.

This chart (par.

hard-to-find troubles.

be overlooked.

to

that

appear

the trouble

by

it

may be caused

76)

If

present, this type of

tapping or jarring the

is

not in the radio itself

by

circuit

trouble.

is

not

can be

external

61.

Troubleshooting

Ta

ke advantage of the material

rapid location

Fig. No.

22

___________

24 ________________ _

25 __________ __

26 _

_______________

27

________________ _

28 ______

29

___

32

_________

62.

Test

of faults. Consult

_

____

__________

____ _

_______

Equipment Required for Troubleshooti

Data

in

this manual.

Lhe

following troubleshooting data:

Description

Ilaciio Receiver R-520 /URR, ave and bias system. Power supply circuit.

_

Filament circuit.

_

Radio Receiver

Voltage

_

Top view of chassis.

Bottom view of chassis.

_

Dial cord drive system.

11.nd

R- 520/

URR,

chassis removal.

rcsi.;te.nce diagram.

The test equipment required for troubleshooting

Th

e technical manu

als associated with the test equipment also are

listed.

365011- 55- 5

It

ng

will help

is

in

listed below·

the

65

Test

l'QUipmen~

TM

---

TM

TM TM

TM

'f

l\

l 11-5500

lt

-F

Sip;

nal

Output

Frequency

l

"lc

ct

,

Tub

e T

Audio O:icillator

\1ullim

.05

-µf

Generator

Meler

ro11i~

~lultimctcr

este

r l 177, I- 177- A,

ete

r TS-297/ U -

capacitor,

S A

Hot

TS

-382A/U

400

ot.

Sf'R-21

T

vdcw

TS··585/U -

N/ UR;\l

---

!

-(•)___

S-505/U,

or

_________

.

•

-

or

an

cq

--------

25 -

an

uiva

cqlu

----

----------

--ivalent

t - -

en • -

------·---

----

--------

--------·-

- ----

------

. o 1-µf capaci t or, 400 vclcw. • us-ao-(•)).

Low-iinpedarwr. hcadKct

I

63. Genera recauhons f lly whene

P

Observe the followmg precautions v h

Lhe

. .

radio receiver. r

a.

If

availn.blc1 uso an isolation Lrnnsforme

and the receiver.

b.

Be

careful when

voltages

mo.king

Lhe m1s1UmemenL.

are present. . d

c.

Dis

connect the external power

repairs. .

d.

When

working

ganged Luning capacito1· plaLes;

. s tb.rea

e.

Do

not

overtighten screws inserted thrOU r

plastic materials.

j.

When changi

rep

lace

the

lockwnshers.

g.

Carclcss replacement of

Note

the following points: 't,ion of the

(1) Before

l£

the

· ' pus

t1ons,

(2) Be careful

them

(3)

Do

not

may

(4) A

It

cn.ro

is

soldered joint is one of the most difficult

(5)

When a part

placed exactly

the cause proper groundmg when replacing a

(such

a.ci

II

cadiicL

· ver

. .

the

boLtom

on

the

top

This

might

ng

a componenL held

parl

n.

part

is unsoldtwed,

parL, such

tag

each of the leads. ulJing

ouL

of

as

a transformer

not

to

damage

the

way. receiver;

allow drops of soldPr

cause short circuiLs. a

lcssly soldered connecLion

very

important

ery

care u .

,ssis is

of

the cha

lm

e cor t

of

the

chassis, Id

this

cou

strip

~he

threads 0 s

by

screw . vito.ble.

s often

makes

note

tho

bas

other lea

to

ds

fall

may

Lo

mnke well-soldered

e.ote

betwe

c~pose

from

the

be car

eful no short or

cause

gh

or

produce

or

faults

new

091

P

umber

a n b' g

by

P

iJ1Lo

the

creat~.

JOlll

fault~

is replaced

as

same

elec~rical

troub

le

1;1l

h-f ctrcu1ts. Give partteuln.1 a

in

the r-f

or

i-f

circuits, 1t

the original was placed. A

v~lue.

but

differenL

physi.c\tention

part.

Use

11-5551

11-5017 11-300

11-5511

11-2627 11-2684A

servicing

power

d.

dangerous

'

outlet

a

d

cracks.

nuts,

llle

of

or

neW"

ts.

find.

to.t

.Pa

r size

the

hne

before

to

bend

ed

into

always

ads.

~ec-

1

co

1Jl

Lhey

Io.ult.

a poorly

must

be

that

btlS

may

to

sa.me

66

ground as in the original wiring. Failure to observe these precautions

tion in the circuit.

64

. Ch

assis

Removal

(fig.

26)

To

remove the chassis from

elow.

b

a.

Rotate the tuning control knob counterclockwise until the dial

is

at

pointer

b.

Remove the volume control and

pulling

the low-frequency end of the tuning range.

them

off

c. Disconnect the

receiver.

d.

Remove the four line cord adapters and the bracket assembly

(fig. 4).

e. Loosen the two captive screws

(fig-.

4)

to the

chn.~sis,

f. Remove the wood screw

to

the wooden cabinet.

{J.

Remove the three chassis mounting screws and washers.

h.

Disconnect the loop

of

tbe chassis.

may

result in decreased gain or possible oscilla-

t,he

the shafts.

battery

cables and remove the batteries from the

and remove the cover.

that

antenna

case, follow the procedure outlined

t,he

tuning control knobs

that

hold protective cover

secures the

cable from the socket

band

selector bracket

at

the

by

A3

rear

WHIP

ANTENNA

E2~~~~~~~-..I

\

~@

MOUNTING WASHERS

WHIP

ANTENNA

SCREWS

Figure £6. Radio Receiver R-6£0/ URR, chassis removal.

-...::---ic.'-----+----BAND

SELECTOR

MOUNTING

PROTECTIVE COVER MOUNTING SCREWS,

(CAPTIVATED)

SCREW

TM877-26

67

i.

t

nat

j.

Remove

secure

Remove

it

thr

lo

the

whip

llw

cabinet.

drnssis.

ant<•JUrn

65. Preliminary Inspection

When

remove

a. Examin<• for

wax

b.

apparatus, bare

c.

corr~spond

the the

socket

d. InsprC'L

blown

a

c.

f.

g.

or

cables

h. Insp<'ct for loose

11

niclio

set,

the

rN·ciYrr

lcaknge

Inspect, for broke11

wires

and

as wrll

LhuL

touC'h

any

ns

Be SUI'(' !,hat the

lo

thr

conect

mstruction

wrong

contacts.

fus<• Inspect Check

InspcC't nil POWC'J'

thnt

book. RephH·c

numbers.

the

fuse>.

is fo1md. ·

the

dinl

nil

swikhes

ti.re

broken.

is

bmught from burned

discoloration

c·onncdions

for

tli1•

chassis

markings

Rrplac·e

Check

meclinnism.

and

plugs

or

missing

h,\

.

in

the

C'11sr

insulution

of

dcfc<'Li\(•

or

0

t,ubt• t,ypcs

OJ"

broken

c·nrcfu

n<'

eontrols

und

C'llbl<'S.

screws.

lnkin~

off

th<•

from the firld for

(par.

64) and

and

apparatus

to

tube

solder

ot.hcr

wirrs.

1 the

1

tubes

for

interchange

tubes.

lly for

surc

tbnt

for

ease

Repnir

inspect

resistors.

u11d

sock<•ts,

co11nc·rtio11s.

in

thcs<'

positions

un,r

Inspect

short

th<'

of

opcrntion.

01· r

two

wire.

the

circuits

din!

eplace

nuts

<'110ck

as

followi<:

Examine

plugs,

Examine

various

tubes

for loose

Lw·ns

and

wnshrl\

or

repair,

fot·

nnd

othet-

fol'

~ockc_l~

g1vm

ha\()

1

,'l

as

that

tub()

whcnovel'

smooLhly.

an)'

plugs

66. Checking

a.

Trouble

the

resistance

. t

p

,

0

ve1

supph with

di

those

at

associated check

t B . me chc<'k

o -

s

hould

f'1

l

nment

output. Use

6

7.

a.

ll.llC'e

o t

portion

. • 1

110

sconnected. Th

list

that

point.

b.

A

partial

for

w1Ll1

be

this

Operational

OpernLr checklist

Key

Circuits for

wiLhin of

1

it•

<'qu1pm<'nt,

power

ed.

How

part

troublc

thc

1

,noo

cil'cuil, rcsisLunco

Figut·<' 24

diagrum

thr

(par.

the

th<'

fila .

. menL

of

the . .

appli<'

short

and

cce1ve1·

1

o

rea~lin

eve

r a

'

on

eventunu'.

of

th.is

on-off ohms.

shows

with

the

Test

equipment

41).

Shorts

re('eivrr

and

thercb

to

·

1

tle

rcc·c1vcr

~s

~1:ny

iea

mg

B-L . . . { some

11

)

1

.

1

11:1

shunt

B

111

<

1·

<'s1s

C'

k"

volu~c

'1'l

the

vol~

g

as

closer"b .

This

check!~

68

oft,

en

may

l11gh-voltag<'

' . .

.)

prcventmg

Th

:sc

measurcmm~s

and

vtu-y

slight

noti

c·eably

line

will

cause

<'

pnrt

will

th

, e

0

~Hrol

d n.ncc

;oltng<' di_sLribution

7

resistance

switch

L · 1

measurcm<'nt

nc·r·oss

nod

re.s1st1u1cc•

c~ 1~

ist ts unpo1·tanL

J

•t

,

0

c ' € N • lying circuits

wiLh

ly in

different. indicates

become

. f

part

tho equipm

·tcd

damage

•

the

some

overheatlllg

rom

in

t,hc

of

Lhe

in

diagram

because

by

checking

before

are

on

app

to

the

power

b made

to

o

bles

?attery

instance~

defective.

me

power

the

ent

c~roin

ble

tiou

0

.

To

f

positi.on;

VS

3 o

. . .

1

<l

es u

u

re('etvc)r.

(fig.

I,

supp}

27

10

pei:forn.1-

1L

fic-

it

·

RTI

NOTES:

I.ALL

MEASUREMENTS MADE TO

COMMON

2.VOL.TAGE RESISTANCE READINGS

3.VOL.TAGE UNDER THE FOL.LOWING

4.RESISTANCE MEASUREMENTS

~*INDICATES

6.

NC

B·

BUS.

READIN

GS

ARE SHOWN ABOVE

BEL.OW

MEASUREMENTS MADE WITH

A. RECEIVER OPERATING FROM 117-V B. BAND SWITCH C.

NO

SIGNAL INPUT.

CONDITIONS:

A.

LINE

CORD AND NOT INSERTED ON·OFF

B. C.

t INDICATES MEASUREMENT MADE WITH ON- OFF

VOLUME

INDICATES

SET

PLUG DISCONNECTED FROM POWER SOURCE,

VOLUME CONTROL SWITCH

CONTROL SWITCH CONNECTION SOMETIMES MADE

NO

CONNECTION.

LINE.

COND

ITIONS:

FOR

BROADCAST OPERATION.

MADE UNDER

IN

CHANGEOVER SWITCH S4.

IN

Figure 27. Voltage and resistance diagram.

5.6

8.

l. IMEG

OL.T

ON

48

72

2V

VTVM

4V

LINE,

IN

POSITION

PWR AMPL

V5

3U4

v

OV

0

l.

4 V

16

-

.IV

15

"4EG

A·C

POWER SOURCE.

THE

FOL.LOWING

OFF POSITION.

.

INTERNALLY.

85V

l

.8Kt

87V

l.

5Kt

IV

2MEG

6.

95V

2

.5

26

87

2.

4K

87V

.

4K

4.2V

33

v

V

I·F AMPL

IU4

V3

CONVERTER

V2

IL6

R-F

AMP IU4 VI

L

2.8 V

l

.4V

16

.85V

2.8MEG

TM877-17

quently indicates ground noise in

b.

Check the on-off switch

the

general location of .trouble.

receiver

or

for received signals. f ositive

and

volume

control

Listen

or

P

and smooth control of volume. . . a

c.

Try

the tuning control for smoothness WJthout

d.

Check the

e.

Extend the whip

band

selector

antenna

buttons

and

for positive operate

~lipp

o.ctio~~er

the

rece i

to check for signal pickup. .

f. Correct ave action can be checked

on

strong signo. s.

loading or distortion should occur. .

g.

No microphonics should occur on a strong signa

volume control

h.

Use a frequency meter and check

i.

Fino.Uy,

set

tap or

at

maximum. _

the

jar

the

set

to

make

. ·

cahbro.tion nnections

certain

no

loose

exist.

68.

Troubleshooting

T

ble

a.

an aid

(1) Coupling capacitors between stages

h

rou s ooting

in

troubleshooting the receiver.

d

pro uce on the capacitor for leakage disconnect one

d h

an c ec its resistance; use the highest

Radio

·

A,:"A

hi

h

a.

g resistance

~.

Recei

ver

R-520/URR li d

Th

o following inforrno.

.

short that

grid of the following tube.

. .

k

• .

t.

on

1

can

beco.rn~.

places a a suspected

To

positive

check pacitor

lead of the

resis-

the ohmmeter. f

(2) I · one o

mproper ave. action

bypass capacitors,

1U4 r-f tube V1 1L6 ' .

1

a so c.an. e

b , converter tube V2,

~he

can be caused

04,

C43

by

or

C44 (fig. 40).

cause. Figure 22 sho

a

short

JU4

or

ws the c1rcu1

ave d1str1but10n system )

(3)

Wh

vol~:s~g

battery

b.

Troubleshooting

aid in locating trouble in the le . ollowmg toms which the operator or audibly, while making

how

to

sectionalize

signal substitution tests outlined in can

be used to supplement this pro Jara.graphs 70

tive

circuit. A tube check and

of the defective circuit ordinarily defective

part.

. .

~he

~oltage

op::at~o~.

ould be made for

Charts.

and resistance diagrarn

both

Tl

r . pplied as

charts

r

trouble

ep:~~e1ver.

a

few

s·urn~n

guickl;%pt~e

These

may

tests:

observe,

The

particular

vo~~

ure and to.deternune surernent

sh~~:nbd

r

estSt~nce

e suflic1ent

power

are

cha.rt~

eit

charts

stage

OT

thr~ug

for

back

-

action

e.

g

on all

bands

No

1

with

11

iw

over-

the

bands.

1

on

co

as

ky

1

ea

-voltage

ca

nee sea

8

and

le

of

is suPP

~n

the

in def

.

ecti-ve

A:-

t

be

1-f u

V3

·t

of

the

(.fig

27

lin~

and

I

an

~·u

t

the

syrnP-

JS visually or

herlso

indicate

c~1·cwit.

The

h 73 .then

the

defec-

mej~olate

to

the

Note.

First

set

ment

performance checklist (par. 41). Then :

proceed with

the receiver controls as

the

following tests.

10

in

the

r . C

eraratory

PP

Y power

sect

to

tbe

ion o ceiver and

the

re

equip-

(I)

Sectionalizi,ng trouble.

...

-

Sympt.om

1. Receiver

tion only. Neon

E,IOWS.

2. Receiver neon

3. Receiver voltage. Neon

not

line voltage

4. Receiver tery

5. Motorboats on

6. Microphonic distortion

7. Distorted

inoperative

light

on

dial

operative

glow on battery,

inoperative

operation.

output

scale does on

dial

operation.

on

broadcast

on

broadcast

light

(2) Localizing trouble.

Symptom

I.

Low-frequency

cuts

2.

out,

No

signal on power line operation _____

no

signals.

end

of

on

battery

on

bat~ry

battery

indicator

but power

band __________ V3,

on

broadcast

dial scale

not

and

lights

line

band

opera-

only; B batteries

glow.

line

does

up

on

or

bat-

band .____

band

Probable

Weak A batteries-

Weak B batteries

Fuse

Fl

open._________________

IU4

i-f

VI,

1U4

_ V 4, 1 U5 detector-amplifier

V4, 1 U5 detector-amplifier

Oscillator coil

__

CRI Poor

r-f

or

CR2

contact

----------------------

dead.

--------------

_____

tube

defective

tube

defective.

Probable

L2

defective ____________________ Replace coil.

selenium rectifier defective _

on

ballast

trouble

- -

--------------

_____ _______________

___

__________ Replace fuse.

___

_________________ Replace

tuoe tube

trouble

adapter

defective defective

socket J2_ _ _ _

•• -·_

___

____

---

Replace A batteries.

Replace B batteries.

___

Replace

__

Replace

__

Replace

Replace Reset

tube.

rectifier.

contact

·B

batteries.

tube.

on

Comictlon

J2

socket

.

Sympto

m Probable trouble

3. W

eak

audio ____

No

audio from

4.

5. H

um

with

6.

Slight

hum

up

.

7. Noi

se

in

selector

8. Weak audio

9. Weak signals

______________________ Coupling capaci

speaker

________________

volume control

with

volume control

speaker

buttons

when operating

.

___

_____

_________________ _

on

all bands, using power

line operation.

10. Signals weak on broadcast band

11. In:.age signals

12.

No

.

lo

No

Signal

is

.

Tone

signa

signals

shifts

jarred.

control

13.

14. Receiver breaks

15

ls

on

at

7.9 me

frequency

on

broadcast

4-8

MC

band

________ _________

into

oscillation

when

buttons

break

band

___________ _

turned

down__

turned

band

_______

______ _

at

7.9

me_

the

receiver

oft _____ __

Gr

id bias resistor R18

Headset Filte

jack J3 open __________________ ___

r capacitors C45A, C45B,

fective.

C21 audio grid blocking

Dirty

contacts

Tone

control resistor

Filter

capacitors C45A, C45B,

B+ voltage.low.

_

Converter

Ave

Band

_

Capacitor

Trimmer

Coupling Converter

Filament

Defective

H -f oscillator

Lead

__

Receiver

grid

bypass

selector

C39

capacitor

tube

bypass

band

wire

capacitor

to

chassis

tor

on

baud

coupling

contacts

open

___

C40A

C37

1L6

defective ____

capa.citor·Cg

selector

capacitor

oscillator

not

taut

not tightened

C24

partially

has

low value resistance_ -

C45C

capacitor

selector

R32

has

switch

low

C45C

capacitor

C4

open

____ ---

defective

_______________

____ ___ ______

shorted

open

______________

__________________

open

switch

contacts--------

C12

shorted _____

section

C2E 0£

.

to

shorted

______ _

__

open

or de-

defective

__

- - _ - _ -_

____

resistance____

defective;

C7

open

______

-------

__ __

------

--

______

--_____

____________

_______ ganged

ca

binet

_______

Replace Replace

_

Reset

contacts.

Replace filter.

_

Replace

Clean

ide.

31. Replace Replace

Replace Replace

Set

contacts

Replace Replace Replace

Replace Replace

Set

band

Replace Dress

and

ch. 5).

Tighten

I

Correction

capacito resistor.

capacito

contacts

Refer

resistor.

filter

capacitor.

capacitor. capacitor.

for

capacitor. capacitor. capacitor. tube

.

capacitor

selector

capacitor

wire away coils.

the

chas

r.

with

to

caution,

positive

.

contacts. .

from

Che

ck a

sis mou

carbon

tetrachlor

in

paragraph

action.

capacitor frame

linement

(sec.

nting screws.

-

III,

17. Receiver

noise

when loop

position

18

. Signals

No

19.

20. No signals

weak

signals

on

bands.

21. Set

22.

23. Signals weak

24.

25.

deacl

or

All

shortwave

whip

antenna.

SignPls weak

spread

bands

No

resonance

capacitor

26.

No

resonance

capacitor

27. R

-f

tr

immers

28.

Broad

peak

and

9.6 me.

29.

Broadcast

signa

band

ls are weak.

present

antenna

over

cabinet

at

3.9

me

on

16 M

band __________

16, 19, 25,

off calibration

bands

weak when using

at

3.9 me ___

on

16, 19, 25,

.

at

3.9

me

C35B.

at

7.9

me

C35A.

C35A, C35B,

at

17.Smc,

does

15.2mc,

not

on

broadcast

is

swung

or when

or

7.8

and

31 M

at

____

for r-f

for

r-f

broad

calibrate

band

up

into

jarred.

me

______ _

___

spread

3.9 me_ - - -

________ _

and

31M

trimmer

peak

__

ll.8mc,

and

Riv.,t

or

assembly unsoldered,

broken.

Plate

coupling

ance

Oscillator coil

_

Defective

Oscilla

Coupling

leakage.

tor

itor

C38

Coupling

contacts

coil

capacitor

resistance.

Capacitor

C41

Oscillator coil Telescopic

R-f

Whip

capacitor

trimmer

antenna

whip

capacitor C35B

C34

open.

Trimmer

Trimmer Coupling

Coupling

Three

capacitor

s'\\.jtch

has

capacitor

switch

has

capacitor capacitor

itor

C38 open.

section

mounting

defective

screw

pins

capacito

L2

open ___

on

L2

has

C37

open,

or

open

___

L2

h~c;

antenna

canacitor

open.

C35B

C35A

defective

C34 C36

ganged

shorting

of

front

cover

or

solder

r C6

open

or

___________________ _

band

selector

shorted turns

open. Coupling

high

leakage

C42

open,

or

_____

---------

shorted

turns

capacitor

C27

shorted ___________

C27

open.

Cou

pling

capacitor

shorted.

Band

contacts.

shorted.

contacts.

open open.

capacitors

Band

_____________ ____ _

Coupling

C2A, C2C,

to

capacitor

hinge br

acket

connection

high

resist-

___________ _

__

--- - ---- - capac-

resistance.

high

leakage

-------

_______ _

open

___ ___

Coupling

C33

selector

cspac-

C2E

stat.or.

Resolder rivet

Replace

Replace Reset

Replace

- _

Replace

_

Replace

Replace Replace

Replace

selector

Replace

tacts Replace Replace

Set

ance.

(fig.

33)

capacitor.

coil.

for

positive

coil.

defective

capacitor coil. capacitor.

defective defective

trimmer

contacts

trimmer

for

positive capacitor. defect

capacitor

pins

.

action.

capacitor.

.

capacitor. capacitor.

capacitor

for

capacitor. Set

action.

ive

capacitor

mountmg

to

mounting

positive

.

screw

. Set

action.

·

for

br11olo:et

band

con-

clear

-

Symptom

Probable

trouble

Correctlqn

\

I

30.

No

31.

No

32.

33.

No

Nci

34.

35. No

36.

Broadcast

37. No resonance

---

~

Oscillator coil L20 does

-....JJ.,_

455-kc resonance for i-f t ransformer

T l secondary.

resonance for

at

1,420 kc.

resonance

tr

immer resonance for loop

C2B

at

resonance for br

trimmer

resonance for

converter trimmer

at

3.9

C31A.

1,500 kc.

oadcast

C2B

.

broadcast

me

for

antenna

loop

r-f t

C2D

antenna

trimmer

antenna

rimmer

C2D.

band

does

not

calibrate.

on

16, 19, 25

8

me

or

antenna

31 M

or

r-f

coils on

spread bands.

not

resonate

Resistance R14

Capa

citor

Open

secondary

Conver

Antenna Antenna

Capacitor

wires from are

too close

Signal grid

vert.er

Oscillator coil L2 Band

selector switch

Lead

at

wire from oscillator coil

1L6

C44

open

ter

coil Ll

<'.Oil

L5

loading coil

C30 too close

the

lead

tube

is

converter

has

too

low a

value

or

has

winding

high

on

T L _______________ Replace

open ____________

open·----

loop

to

the

wire

too

has

tube

L4

open

to

antenna

chassis. to

close

shorted

has

is

too

---------- -

metal

to

metal

defective

dose

___________ _ Replace resistor.

resistance short.__ Replace

___________ Replace coil.

--------

_________ .___

chassis.

to

loop receptacle

No.

6 of 1L6 con-

Lead

____

Replace coil.

Dress

from

Dress the

chassis.

turns

_____

L20

to

______ _

contacts ____

No. 3 of

the

.chassis.

Replace coil.

_

Reset

Dress

chassis.

capacito

r.

transformer.

capacitor

the

c~is.

wire aw:. y from

contacts.

the

lead

"';re

I

and

lead

away

wires

the

Crom

\

away

chassis.

the metal

Figure

f8.

Toi>

mw

of chauia.

75

CR

I Fl

RZ7

C46 54

TM877•

Z9

76

Figure 29. Bottom view

of

chassis.

SIA

SIB

J

.l

4

Figure SO. Rear

...

view

of

chassis.

TM877

30

69.

D-C Resistance

The

d-c resistance

Transformer

LI

conver.er grid coiL _ _

L2 osciUator

L3 r-f choke coiL ___________

Tl

i-f transformer____ _______ l

T2

i-f transformer_ _ _ _ . _ _ _ _ l

T3-

---------------·-------

E2

____

--· _ -----_ ___

or

coiL

of

ooU

__

__________

_ _

__

__ _ Broadca

Transformers

the transformers

_ _ AB ___________________

CJ)

______________________________

AC

--------------------------

BJ)

______________________________

EF

_______ ------__

IIG-

-------------------------------

---------------------to 8 ____ ------- -----------------__

4

to

5

_______

to

8. - . - ---- -- - - ---- - -- - - - -- - - -

6

to

7

_____________________________

Primary

co

Voice

Inverse

and Coils

and

coils

Terminals

winding _______ _

il

winding. _______________ feedback winding st

loop

or

winding

----

------

----

--------------

____

__________________ _

____

___

---. --

----.

are

listed bel

________

--

----

-----

_____

__ __

__ . ______

---

--

_ _

__

_ _

_

R

esistance

(ohms)

8

6.

8.

3. 2

23

25

280

3

13

. 7

ow:

l

. 013

2

.7

70. General Signal Substitution

a.

Signal

If

available, use

substitution

an

isolation

requires a source of audio, i-f,

Note

s

transformer bet

ween

-and

r-f signals.

Lhe

power line and

the receiver.

b.

Note

speaker or

the volwnc,

headset

and

listen

for serious distortion from the loud-

at

the various points in the sii;nal substi

tution

procrdw·e. Where possible, compare operation with a receiver known

be in good condition.

to

c.

Check the wiring

and soldering

in

e

ach

stage

during the proce-

dure.

Note.

Do

not remove r-f

the

tuned units,

unit.

Do

not damage wiring by pushing

Be

careful

not

to damage

d.

Misalinement of one

reduced

output.

until

Misalineme

and

i-f shields from

the

trouble b88 been traced definitely to

the

receiver

In

any

or

mor

e stages

nt

of the h-f oscillator

the

chassis, or shield cans fr

it

back aud forth

other

way.

of

the receiver will cau

the particul

dur

iug inspection.

may

prevent

a

om

ny

output.

e.

When

tr

the voltage,

uble is.localized in a

and

measure the resistances

giveu

sLage,

at

Lhe

test

the tube, measure

tube socket of that

stago ·(fig. 27).

f. Trouble in a circuit

and resistance measurements

in

this paragraph

cedures, such as voltage

are

or

stage

may

at the

tube

merely a guide

and

resistance measurements on individual

not

cause changes in voltages

socket. T

and

should suggest other pro-

he

no'tes included

parts.

g.

Remove onJy one

tube

at

a time when testing. Check

the

type

ar

se

78

number of the tube

it

to

its

proper socket before removing another tube.

h.

Each

step assumes the satisfactory completion of all previous

and

steps. Isolate and clear

a.ny

succeeding steps.

test

the tube.

any

trouble located before proceeding with

If

it

is

not

defective,

retwn

71. A-F Signal

Under normal conditions, with mum clockwise position, center lug of

(milliwatt) of power to audio-output transformer secondary. equivalent, by

means of Plug PL-55. (The speaker voice coil

automatically.)

generator

output receiver; for example, 0450,

C45D,

Subs

titution T

ests

the

25

mv

(millivolt) of audio signal fed

the

volume control will deliver approximately

a 3-ohm resistive load connected across the

set

for a 3-ohm lo

The

shielded

ad

may

be connected to headset

or

ground

cable should be connected to

the

negative lug of filter capacitor C45A, C45B,

or

the negative filament (pin 1) of t,

volume control set to

Ou

tput

Meter TS-585/U,

is

disconnected

Lead

of the audio signal

the

B- hus of

he

1U5 detector-

its

jack

maxi-

to

50

or

the

mw

an J3

the

amplifier tube.

a.

Apply a 25-mv, 1,000-cycle sine wave audio signal from

audio generator through a

lug of volume control potentiometer

.05-µ.f

(microfarad) capacitor to

Rl

7, and turn the control to

the

center

its maxim.um clockwise position. A high volume audio signal sh.ould come from

load

is

the audio

headset jack, tubes

used,

output

the

speaker or,

it

should read

if

an

output

50

mw (0.4 volt ac).

is low, check the speaker, the

V4

and

V5,

and

meter connected for a 3-ohm

If

there

i.s

no

output

the

capacitors and resistors in

transformer, the

audio or

lihe

associated nudio circuit.

b.

Weak audio or audio with distortion or hum further of on

by

feeding

VS

and

then to the center lug on

full)

and comparing the two out.puts. Approximately

the

audio signal first to

the

volume control (volume control

the

can

be localized

signal grid (pin 6)

50

times as much audio power should be developed with the volume control connection sa

as compared with the signal grid connection of V5 'vitb

me signal level from the audio generalior.

the

72.

1-F

and

Converter

a. Adjust

the

signal generator to 455 kc with 400-cycle 30-percent

modulation applied. Apply

Signal

Sub

stitution

this signal in series

to the signal grid (pin 6) of the 1 U4 i-f

or ground Jead of the signal

volume control to

its

genera.tor cable to the B- bus and

maximum clockwise position.

selector to BC.

b.

Connoct an

With a

V3,

3,000-µ.v

approximately

output

meter with Plug PL-

(microvolt,) signal fed to

50

mw should

be

developed

Lube

Tests

";th a 0.1-µ.f

V~.

Connect the shield

55

into

head

the

signal grid (pin 6) of

at

the output.

Set

set

capacitor

the

set

band

jack

the

J:3.

79

c.

Gain through a stage can be recognized erator tube.

output

The

d.

If

there is no signal or a weak signal when the signal gen

to

the

signal grid, and then

out,put level should

be

is connected to tho signal grid (pin 6) of have a shorted be shorted,

or

an open winding; capacitor C20A or C19

the

transformer may be misalined, or tube

defentive.

e.

If

the

output

(pin

6)

of V3, connect

1L6

converter tube V2. With

100

µv, with 400-cycle 30 perc

power should be developed ncross

j.

IC

there is

open winding; capacitor

may be misaJined, or t,ube

73.

R-F

Signal

Check generator of the

for

Lhe

r-f st,age for proper operation by connecting tho signal

output

1

U4

r-f tube

50

mw into a 3-ohm load. Any deviation from the val

below indicates misalinoment or

is normal for a signal applied to the signal grid

the

signal generator output lead to pin 6 of

the

signal generator output set for

ent

modulation, approximately

a 3-ohm resistiYe load.

i10

signal or if

Substitution Tests

it

is weak,

016

or

017

V2

may be defective.

may be shorted,

lend with 400-cycle 30-percent modulation

Vl.

The

following sensitivities should be measured

a defective component.

higher

V3,

Tl

by

connecting the g

to

the plate of the sa:-

at

the grid connectio e

i-f transformer T2

V3

may

ha~e

a shorted or an

t,he

tra

erat:·

mar

ina~

may be

50

:rnw

nsformer

to

pin 6

ues

listed

of

Dnnd

Broadcast -

4-8 i\l!C _____________________________________________________

2-4

l\1C __

Spread·--

---------------------

-----------------------

---

------

-

-----------------------

-------

-------------

-----------··----------------------------

--------

- - --

---

74. Antenna Stage Test

Since a loop typo antenna, whip wire antenna arc antenna sensitivity

incorporated

will

vary

used in the moasuremonts. Check loop antenna E2

El for shorts and open connections.

75. H-F Oscillator

Te

st

Check the h-f oscHlator for proper action tube voltmeter from the oscillator grid (pin tube to

tho negative side of tho filament (pin 1). The following

voltages should be road:

80

ant

enna, and provisions for a long

in

Radio Receiver R- 520/U

considerably, depending on

and

whip antonna

by

connecting a vacuum-

4)

of the

1L6

Input

voltaire

(uv)

lo

to

ao

40 to 70

_

40

to 70

30 to 75

RR

coudit

i

o~

converter

H·f

--

oscillator grid

voltage

-4

to

-9

- 3

to

-5

-3

to

-7

-2

to

-4

v v

Band

Broadcast--

2-4

JMC----

4-8

JMC----------

Spread--------

76.

a.

------------

------

-- ----------

---

---------

----

----------------------------------------------

---

-------------------------------------

----- --------------------

Stage

Gain

and

Sensitivity Chart

When checking stage gain or sensitivity, observe the following

----

-----

----

---

points:

(1)

If

availabl

e,

use

an

isolation transformer between

the

power

line and the receiver.

(2)

The

dummy antenna for external antenna operation consists of

a 400-ohm resistor

in

series with a

200-µµ.f

(micromicrofarad)

capacitor.

(3)

The

20-µµ.f

the

(4)

When using

dummy

20-µµf capacitor

antenna for shortwave operation consists of a

capacitor. Disconnect the whip antenna and connect

to

the

whip antenna tip jack (fig. 26).

the

external antenna or whip

antenna

dummy

connections, connect the ground lead of the signal generator

to the ground terminal

(5)

When checking the r-f amplifier, connect the signal generator

output

to the grid of the r-f amplifier through a

blocking capacitor. Connect the ground lead of

generator

(6)

The dummy antenna for broadcast operation is a

to

the

of

the receiver.

B-

bus of the receiver.

0.1-µ.f

the

signal

standard RMA (Radio Manufacturers' Association) test loop (par. 95). Do

not

ground the signal generator

receiver when using the

b.

The chart

of

the

r-f

50

mw which is equivalent to 0.4 volt

Use this

chart

all gain of the receiver

When checking the sensitivity

locate

the

below lists the average

and

i-f stages of the receiver to produro a signal

as a

stan

dard

when trouble shooting to check

and

t.he

go.in

of

test loop

and

the receiver loop and parallel to each other. Under at

the

receiver loop in µv

the signal generator

/M

output

(microvolts per meter) will be one-tenth

voltage. When the receiver

low, localize the defective stage

of each stage against the

chart

while using either the signal tracing

RMA

test

input

ac

across a 3-ohm resistive load.

of each stage, or group of stages.

the receiver on the broadcast band,

19%

these conditions, the field intensity

by

checking the signal voltage level

output

cable to

loop.

voltages required

output

inches

apart

on centers,

at

each

the

over-

output

the

of

is

method of troubleshooting or measurement of tho individual stage

gain.

:msou-ss

11

81

Band

Broadcast

'2-4

4-8 31

25 M ... ------

19

16

•••.

---·-····--·---

MC

..

----------

MC

....

------·····------

M

-------------···--------

M

---

-------

· ·

----------·--

---

-----------

M-------------·----------

··------

Test

quency

(mo)

(modulated

ao

percent

et400

cycles)

-

--

Cr&

o.

1.

2.

a.

4. 2

7. 8

9. 6

11. 15

17.

6 5 1

o

8

. 2

' Average

R-

ramcu-

tier

~ln6oC

I)

8

IT

C,.v)

20

d

20 35 40 85 50 20

20 30 25

SCD!ltlvlt}'

J,oopan·

tennB

(J.v{M)

--

------

--------

--

--------

---

--------

----

--

-----

----

-

--

ut

(~P

OU

pu

WblPBll)

t811J)8 {j.V

--

...

65 50

--------

--

---

t)

-

. . acb cucuit

c.

The following chart lists the approximate

in the r

as of signal generator voltage required

output. Divide the

ece

follows:

V2

to

iver. For example, the gain of the r-f

Measure the signal generator voltage req Measui·e

produce 50-mw

output acro

at

first reading (the larger one) by

ss a 3-ohm load. d

pin 6 of

g111n

for

st

ag

Vl

to pro u nd reading

t~e

to determine the stage gain. When making stage gain be sure to connect the ground lead of the signal genera.to

bus.

--------

---------·-

R-f amplifier

Converter

I-f amplifi

De~ampllfier

Audio

output

----.-

Stage

•••

__

_______

---

er

•.

_____

_____ ---

_______

--------....,-~---o-------'

Test

trequcnoY

(modulated 30

percent et

cycles)

------

600

kc

• .

455

kc

.••.•

455

kc

.•

4

cps_

00

400 cps

400

••.

- - -

____

.•..

--

20

100 3000 µV

25

1.6

--------

•.

__

_

Pin 6 of

__

_

Pin 6

..

_.

--

Pin 6

__ _

Pin 6

point

'l'eat

Vl

of

v2

6

of

va

of

V4

of V5·------

:·-----

.::::::

-------

~~~~~~~~~..!__~~j__-~

for

'

eo-mw

required

-

Bmrnal

anWlll&

(ii•)

--

6

----

~

uire

......

28

5

9 3 3 4

4 6

~

measured

isd

ce

5

00

2

0

2

0

20

1

5

2

5

30

40

,.t pin 6

••

the

same

sec~ureJJlents,

01

~.

to the

B-

---

.,\vera&

e

a

••

• •

taJO

galll

_

-

5

30 28 65

14

-

Jnput

___

µV

rnv

vo

-·····

-····

------

1•a

..,

Section II.

77. Replacement

h

Most o t e

and easily replaceable. Figure 29 shows the location of

f

of Parts

· R d' ssible

t

par

s m a

REPAIRS

io Rece

iver R

-52

0{URR are acce h

parts

beneat

the chassis. t

a.

Wh

en the band. selector switch assembly requires r eplacemen ; carefully mark the wires connected devices installed. R

to

a.void

efe

r to figure

errors in connections when

31.

to

the switch with tags

the

or

otb~

new switch is

82

/t

'io1ire

31. Band

selector

switch, rear

view.

Rb. Figure

2

-:

o/URR. 'l'wo

':::

th~

tU:· pomter

Wh

mg

en

h

aft first. '

s

JS.

Front

32

shows the dial cord

dia

other for

.sh~ft

it

is replaced

Cover H inge Repair

the

P~ey,

dial co

it

rd can

the

l cords are

pointer pulley.

is necessary to remove the. dial

be strung without removrng cord should be strung around the tuning

The two hinge bracket a."8Semb the electrical circuit the

~eceiver

nection on mittent fo

llows:

a.

Disconnect the loop

(fig. 33). A broken wire or a loose or broken solder con-

the

operation on

that

connects

riv

et

pill will create electrical interference

the

broadcast band.

ant

driv

e system on Radio Receiver

used-one

lies on

the

for the dial tuning shaft

To

replace

the

front cover are

loop antenna on

To

enna. cable plug from

the

dia.l

cord for

sc~e.

the

The

dial scal

part

door

or

int

e.

of

to

er-

repair, proceed as

the

set.

83

oRWE

PO\NlER

PULLE'<

,.

--

.....

'

...

'

' \

\

0

I

,,

,;

,,

SHOULDER

Rl'J

El

\lURN

Ol~L

coRO

F

igures~.

D

io.L

cord

drive

1M877-'32

system·

84

RIVET PIN FOR LOOP ANTEN

NA

SOL

OE

R CONNEC TION

Figure

SS.

Front

cove

r

hi

nge auembly repair.

b.

Remov

e the volume control knob

c.

Remove

64).

d.

Remove

net

and

e.

Remove both

net

and

f.

Take

cabine~

g.

Remove

to

the

assembly

h.

Resolder

mounting

79.

Refinishing

Instructions for refinishing badly marred cabinets are given

paragraph

the receiver chassis

all front panel screws

remove the front panel.

screws

remove

and

top

the

out

the five wood screws

remove

the four wood screws

of

the

cabinet

from

the

rest of

the

broken solder connection of

bracket and reassembl<'

37.

that

handle.

the

panel.

the

and

hold

remove

cabinet.

and

the

tuning control knob.

and

batteries from the cabinet (par.

that

secure

the

handle to the top of the cabi-

that

hold

the

in

the reverse ordex.

the

panel to

hold the top panel to

both

mounting brackets

top cover with the hinge

the

i·ivet pin to the

the

cabi-

the

in

Section

80

.

Test

Equipmen

a.

Signal

Generator ment capable of producing modulated and unmodulated r-f signals.

'l'h f .

e roquency range

ment frequencies are shown in

noccssa~·y,

mental

of

l2.5

~t

l

e.o.st

~-£

cn·ctnts. Accw·ate frequency calibration of

1

s.

extreme ly important to insure

will

be correct.

b.

quencies range of must

TS

- 585/U (or equivalent),

c.

not available, a frequency meter can be used to check of

the generator. Frequency

purpose.

d.

loudspeaker rough

Generator.

Set

tbe second

ts

not

available. 'Phus, a signnl generator with a top frequency

rnc

also is suitable. 'Phe generator should

,5,000

Output

Meter.

and

500

match

Frequency

Headset

or

alinement.

Ill.

ALINEMENT

t Re

quired for

The

signal generator (such

AN /URM-25)

must

haL·monic

µ.v

for best results in alining

The should provide readings mw.

For

the 3-ohm voice coil winding. Use

Meter.

or

Permanent Magnet Loudspeaker. The receiver

a.

h~adsct

must

extend from

the

generally can

output

correct readings,

W11

(such as Headset HS-30- (*)) can be used for

meter should respond to audio fre-

set

for a 3-ohm load.

en a hjgbly accurate signnl generator

~fetcr

PROCEDURE

S

Alinement

as

be an accurately calibrated instru-

400

kc to

25

me.

alinement chart (par. 93).

be

used when the funda-

hav

e an

the

r-f, h-f oscillator, and

the

signal generator

that

the

receivel' din! calibration

at

50

mw

and

hav

e a maximum

the

impedance of the meter

Output

BC-221

-(*)

is suitable for this

RF

The

output

the

Signal

alme-

Meter

accuracy

If

of

is

85

14

0

e.

Alinem~nt

receiver

and

Tools.

an

insulated

The

alinement

screwdri:e~

Caution: Alinement tool 0 14 is

and

r-f transformers.

capacitors

81

. Calibration of Signal Generator ·ator

Tbe

tion is

a.

the

use

as follows:

b . .

the signal generator

82

.

a. Remove the cha · f d

tions in paragraph

b.

and

the

c.

to conform to

d

. onnect the power

the receiver on

(I-)

( (3) Connect a

(4) Aline

or

as a screwdriver.

procedure below is used on not

acceptable. . . t

Accurate alinement

of

the

frequency

(1) Place

(2) Calibrate

(3)

Attach

(4)

~et

(5) While

i:ieter, signal

Turn

Pr

eparation fot Al·

If

available, use .an . . n

receiver •solat1on transformer

Be sure the.power su . .

C

Turn

S

2)

into

order: c ions of

the

Turn

them

minutes. .

furnished

a piece of wire to

Lion

and

the

meter

1s

to be used.

li

stening to

tune

generator now is

off

the

frequency

the

po

and

the

volu-

et

the receivei· f . b o its maxunum

jack

J3.

the

Do

not

att~mpt

ly

when

of

the

b-f oscillator

meter

generator

on

and

the

frequency m

with

the

place tho wire

to

the

generator

output

•n

ement . h instruc-

ssis rom

64

Pply

wer source th . . bl T

let itcord to the external

warrn

•ue

control t . . I ckWJS

3-o

l

un.o~

va.rious se

to check t

and

frequency p for

allow

them

eter

unit,,

the

near

e.xact frequency to

the headset

to zero

set

for

meter

connection.

roadcast operation. d j,nsert

utput

and

the

cabinet

adapter

at

1s

up

for

meter to

t'

1

too,

are

mtende

re;tre

to

the

he

to

e

'U8

sign

meter

warm

.

d'

~linernent

~;

~or

J'

signal gener

he

~

al genera.tor settmg,

u

to

according

signal genera.tor cter

the

frequenc~

whic

connecte.d

beat

the

frequency

remove

in

accor

betwee

switch 1s

availa e.

pow

5 minutes. .

Plug

the

receiver

t~he

'vith

the

wire

nee

a .

ID

the

er

tine

co

Pir55

in

I-f stage.

Broadcast band.

4-8

MC

continuous cov

2-4

MC

continuous

cov:rra.ge

age and.

bba.nd.

86

supplied

turning

receiver

ear

n 5

the

output connec-

~the

desired.

. attached

the

correct

80

the

with

of

the

trimmer

calibra-

requ.ires

each

other.

at

least I

instructions

antenna.

generator

the

frequency

meter. The

Wl t

pow-er

position

ur

ce

·

position.

6

an

following

the

to

lme

urn

it

i-t

31

M band.

25

M band.

19

M band.

16

M band.

Note.

With

the

signs.I.

generator modulated 30 percent.

the

final

sensitivity measurements are taken

mw

across a 3-ohm load.

83.

1-F Alinement

(fig.

28)

a.

Adjust the i-f transformer cores with alinement wrench 0 14

supplied

the h then ca.ref

mate

done, core coeffic

ad'

BcrewdNver

cycles,

the a.. si usab ground

with the receiver. This wrench should

ol

e

in

the top of the can to adjust the top core of the transformer,

lowered

ul when a.lining these

}

~

c~ntered

it

is possible to advance the top core beyond, tind the bottom

~hove,

its

ient of coupling

Note

Al'

: memeut wrench O 14 is a special purpose tool

JUsti~g

the i-f and r-f transformers.

t . .

0

r o

b.

Set the signal generator to

and

connect

~ta.to

r

terminal of capacitor C2C. The i-f signal

pplied

to

gna

l genera.tor

the 1L6 converter signal grid (pin 6). Do

le reading on the

lead of the signal generator output cable to the

Procedure

through the top core to adjust the bottom core. Be

tra

nsformers to keep each core approxi-

in relationship to

associo.Lod

turn

trimmer capacatora.

its

output

coil. This would result in

o.nd

unstable and improper a.linement.

output

o.ny

output

its

associated coil.

Do

not use

455

kc, modulated

through a 0.1-µf blocking

higher than is necessary to provide a

meter (a.bout 10

at

standard

be

des1gne

the

alinement wrench

mw).

at

output

inserted through

If

this

an

· d ·

pmnar1 Y

30

percent

capaci~r

is

not

Connect the

B-

the receiver.

c:

With the alinement wrench, adjust the top

of

i-f

transformer T2 for maximum output indication on the output

a.nd

bottom cores

meter.

d.

Adjust the top and

output indication on the

e.

R

epeq.t

the adjustments given

bo~tom

output

cores of transformer

meter.

inc

and d above.

Tl

for maximum

400 cycles,

of

50

is

not

incorrect

·1

f

or

aa

at

400

to

effectively

set the

bus of

a

84.

Broadcast

a.

Couple the

Band

Alinement

signa.1 genera.tor output lead through

a.

0.1-µf blocking

capacitor to the grid (pin 6) of r-f amplifier tube VI. Leave the ground load of the signal generator connected to the

B-

bus of the

receiver.

b.

Set the signal generator to 1,500 kc, modulated

400 cycles.

c.

"Press

the

BC

band selector switch.

30

percent

at

87

d.

With

frequency end), mechanically

the

clio.l

e.

Turn

the

scale.

the

ganged tuning capacitor completely meshed

set

the

dial pointer horizontally

tuning control so

that

the dial

pointer

is

set

to

the broadcast scale.

f.

at

1,500 kc.

Adjust

oscillator

Do

not

trimmer

set

capacitor

the signal genera.tor

C2F

output

(fig. 28) for

any

resonance

higher than

is necessary.

g.

Adjust

indication on the

h.

Sot

cycles.

. rr . . . t

i.

r-f trimmer capacitor

output

the

signal generator to 600 kc,

motor.

urn the tunmg control so

C2D

that

(fig. 28) for maximum output

modulated

the dial

30 percent

pointer

is se

to

the broadcast scale.

· R ck h . . d · t' " broadcast

J.

o t e ganged tunrng capo.cit.or while a

pa.elder

output

0

ca.po.ciLor meter.

k.

Repeat

l.

Re?eat

m.

~igw:e

pcmt1on, is

the operations outlined in b through j above.

operations outlined

34, which shows the switch connections for broadcast

shown for reference purposes.

Cl3

(fig.

30) for maximum

in

output

b through g above.

JUS

lllc

.

indicat10n

Oow-

across

150

on

400

at

60

on

th

on

e

85

ou~~~i~co;~ect

jack

ter~innl

cycles. era.tor to 7 .8 me,

on

capacity of be t

output

9

· 4-

b.

c.

d.

e.

Note.

f.

MC

Band

(fig. 31)

Cea

m series with a

~~ect

Alinement

t~e

w

~1ip

the ground lend of the signal

Press the band sele t .

Set

the signal gen c

Tum

the

4- to 8-mc sc!l control

A

djust

.

k

to

a en

. •mage.

Ad1

met

tunin 7 8

oscillator trimmc .

C40A has t r capacitor C40A

the

trimmer

"d

avo1

e.

wo

resonant P . b

Th

. e second P . .

selecting

the

ust r-f trimmer

er.

If

two

reso~

Procedure

antenna

20-µµf

or

sw1tch marked

. oint ts

03

r:

A.

and

connect tho

capac

itor

to

the

wh•P

generator

4-8

modulated

so

that

the dial

omts.

The

correct one

the

f . the

or

~aximum

MC.

30 pcrcen

pointer

for

resonance

is

image frequency, a

output

indico.Lion on .

maximum trimmer capacity.ant Points are noted, use

g.

Set

400 cycles.

the signal generator t

h. TW'n the tuning control

on

the 4- to 8-mc scale. a the

Note.

There

may

be

Receiver

R-520/URR.

two resonant p .

The

corr

0

4

·2 me,

so

th

t . 2 roe

ect

eetti:in~

g or the oscillator coil cores is

modulated

d1al

pointer

on the

shortwave

88

si~no.l

gen;:°'~;

anten , und

to

g10

t

LLt

400

rnc

is

set

to ·

at

7.8

rnc.

..

near

fllllXlrnuro

t e ust

nd

care

rn

st

the

one

neOJe

at

30 percent

is

set

to

4.

d'

coils in

Ra

the

10

one

R7

6BK

TELESCOPIC

WHIP

ANT.

~El

-fJ'.>+-+-+---4---<

LI.

J-"'4--"'--'

L4

8

C3

.OIUF

(

C I

4000

------------

ANTENNA

CIO

.05UF

C9

.

IUFJ

B-BUS

AVC

NOTES:

1.

SWITCH SIA OPERATING POSITION.

2. RESISTOR VALUES CAPACITOR VALUES IN UUF R. UNLESS OTHERWISE SPECIFIED.

C6

47

----

SHOWN

AVC

IN

IMEG

OHMS,

R26

Figure 34. Band selector switch shown

t

'------'

C7

1000

F.

in

BC

posili<m.

C42

120

OSCILLATOR

.OIUF

L2

TO

A

LOWS+

--~

t

SIA

I

C38

I

120

TM877-35

•

farthest from oscillator coil on a that

the

is

the peak nearest the open end of the coil.

i.

Adjust

me while rocking

.

i.

Adjust

output

k.

Repeat

l.

Repeat

m.

Figw·e 35, which shows

operation, is shown for

the

core be

the

meter.

operations

open end of the coil. Images are created

shortwave

set

correctly.

band

The

is

core of oscillator coil L18A,

the

ganged

tuning

core of r-f coil

the

operations

outlined

the

ref

erencc purposes.

whe

n the core of the

set

to

the

wrong peak.

correct resonant point

LI8B fo

It

is

very importa

for

all

other

r resonance

capacitor .

LI2

for maximum indication on the

in c tb1·ough

in

c through f above.

j above.

switch connections for 4- to 8-mc

nt

coil cores

at 4.2

86. 2-

4 MC Band Alinement Procedure

(fig. 31)

a. Use the connections

b.

Press

the

band

c.

Set

the signal

generator

outlin<>d

scJc.ctor switch

to 3.9 me, modulated

in

paragraph 85a.

marked

2-4

MC.

30

cycles.

d.

Turn

the

tuning

control

dial

so

that

the pointer is set to 3.9

on the 2- to 4-mc scale.

e.

Adjust oscillator

me

.

This

is

f.

Adjust

tion on the

g.

Turn

the

resonant

r-f

trimmer

output

tuning

trimmer

point

nearest

capacitor C35B for

meter.

control so

capacitor

C40B for resonance

maximum trimmer capacity.

maximum

that

the dial pointer is set

on the 2-to 4-mc scale.

h.

Set

the

signal

generator

to 2.1 me, modulated 30 percent at 400

cycles. ,

i. Adjust

rocking

j . Adj

output

k.

Repeat

l.

Repeat

87.

31

a. Use the connections outlined

b. Press

c. Sot the signal

the

ust

core of oscillator coil L19

ganged

the

tuning

core of

capacitor.

r-f

coil

LI3

for

for maximum indicat

meter.

the operations outlined in c tlu·ough i above.

the operations outlined

in c throughj

M Band Alinement Procedure

(l:!g.

31) in

parn,graph

the

31 M band

generator

selector switch (9.4-9.8 me).

to 9.6 me, modulated 30 per

resonance

above.

85a.

cycles.

d.

Turn

the tuning control dial so that, the pointer is set to 9.6

on the

ou

90

31

M scale.

e.

Adjust

f.

Adjust

tput

the core of oscillator coil L23 for resonance

the core of r-f coil Ll 7 for

meter while rocking

the

ganged

maximum

tuning

capacitor.

indication

percent

ou

tput

to

at

2.1 me while

io

n on

cent

at

9.6 me. on

at

400

me

at

3.9

indica-

2.l

m<'

the

400

me

the

TELESCOPIC

WHIPANT.

UJ

NOTES•

I SWITCH

2 RESISTOR VAl..UES

AVC

0 El

518 IN OPERATING POSITION

IN OHMS,C

VALUES IN UUF UN

LESS

SPECIFIED

SHOWN

APAC

OTHERWISE

R2

I

MEG

B- BUS

ITOR

I C9

J i

'"

'

10\14

P1

N7

C30

27'0

R24

4.7

c

.

01

Ll2

~

UF

C37

470

ANTENNA

Figure

.'j/j.

Band

3('/rrlor 11ritrh

R-F

~hotrn

in

4-8

.\IC po31t1on.

TM877-34J

88. 25 M

a.

Use

b.

Press

c.

Set

cyc

les. . .

d.

Turn

on

the

e.

Adju

f. Adjust.

output.

89.

19 M Band

a.

Use

b.

Pre

c.

Set

400 cycles . . . ter is set

d.

Turn

15.2 me

Ad

e.

Ad~ust

l

·

output mete

9

16

o.

a.

Use

b.

Press the

40~·

Set

cyc

d.

Ttun

me

on

the

Ad

e. Ju

f . .Adjust

ou

Lpu

t me

. e

F

g.

igure 36

is

shown

91

Ch

·

.

Install

m

paragraph.

after

fina.l

92.

Final

T

he

modulated

a.

B1·oadcast

(1)

92

Band Alin

(fig.

31)

the conn

the

25

tbe signal generator

the

tWling

25 M

sca

le. e

st.

the

core

the

core

meter while rocking tho

the

connect.ions

ss the

on

· .

1ust

M

(6g. 31)

les. ' to

.

19

the

sig

nal

the

Lun

the

19

the core

the

core

r while rock

Band

Alineme

the co

nn

16

M

the

signal

th

t · . t r is set ·

~ umng

16

st

scale. , l 7 8 inc.

Lhe the

co~e

ter

wh

cilo1 e of

whi

for

r~fore

assis

the cha

ad1ustment

Adjustm~nts

following adju

30

Loop

around

nee Purposes

Installation

ssis

64

but

percent

Band

a

turn

broadcast

ement Procedure

ect

ions

out

lin

ed

in

~n.ragraph

M

ba

nd

sel

ector

sw1Lc

h (11.

to

control

of

oscill

of

Aline

M

band sel

generator

ing

control

so

ator

r-f

coil LJ 6 for

ment

Procedur

outlined

ector switch

to 15.2

so that

11.8 me,

that

coil L22

ganged tumog

in

modulate

the

dud

for

maxunurn 1.ntoi·

e

paragraph

(14.9-15·

me,

the

receiver

M scnle. t 15.2

of oscillator coil L21

of

t·-f coil

fog

ect

ions ou

band sele

generator

control

of

oscillnt.or coil r-f

i·o

cking

h " e g

c s.,ows

Ll5

the ganged

nt

Procedu

Uio

od in paragraph 85a. )

ctor

at 17.8 me

so that. the

coil

Ll

th

an

Lhe

switch

switc

4 for

ged

for.r

for

maximum

tuning capac1to1.

re

h (17.5-

modulated

dial

L20

for

ma

xim

·

tuning cap

connec

8

:

~

roe).

6-

l

cl

percent at

30

ter

is

set

pow

n.t

11.8

r.csonan~

· apac1 · c

modulate

eson

18.l

potn

r

eso~a

uDl

tions for

dicat.ion

85~

c).

~

o percent

3

clial

pow

a.llce a b

indi

cat

ion

. .

mc

o percent

3

e

11

ce

a

~

ation

Jll

c

acitor.

1

M

opera

6

·

in

th

e .

do

notc~bmet

s are lnado (

msto.U

.

R

everse

protective cover

Par.

92).

stm

n.t

~~t

s

are rnade

4

. cycles.

of wire from .

loop

antenna E2.

the

with

signal

th e proced(.fig. 4) until

the s1gon

generator

.A.

.

ur

3

1

outp

e

generator

to

outline~

ut

400

11.8

me

me.

on

the

at

to

me.

on

t

at

17

8

•

on the

t'on

1 ,

lend

6

TELESCOPIC

WHIP

ANT.

~El

TO

LOW

CIO

.05UF

Lii

R6

IOOK

l2

A

G

I

NOTES:

l SWITCH SID

OPERATING

2.

RESISTOR OHMS, VALUES

UNLESS SPECIFIED.

SHOWN

POSITION.

VALUES

CAPACITOR

IN

UUF

OTHERWISE

IN

L7

ANTENNA

Figure 86.

C36

1000

R-F

Band

selector switch shown

C34

.OIUF

Lf

4

---------

C37' 470

in

16 M

pi>sition.

OSCILLATOR

t-~

SID

Cl4

120 Cl5

10

C38

120

TM877-37

(2)

With

the

signal

antenna.

indication

(3)

With

ganged tuning capacitor while

maximum

(4)

Repeat

b.

4-8

Mc Band.

(1) Connect

long extended whip

(2)

With the signal genera.tor

antenna put

(3)

With

antenna ca.ted oo the

Repeat

\4)

c.

2-4

Mc Band.

31)

at

3.9

me

era.I

procedure outlined in b above.

d.

S1

Meter Band. Adjust

me, following the general procedure outlined

2

6

cl.

M~ter

me, followmg the general procedure outlined

f. 19

M~ter

me,

fo

llowmg the general procedure outlined

g.

16

M~ter

rnc, followrng the genera.I procedure outlined

h. Protective Cover. Install

93. Aline

The

a.linement instructions

ment

a.linemeot cha.rt below

trimmer

the

signal

the

and

trimmer

as

indicated

the

~uninf?

the

and

antenna

Band.

Band. Adjust

Chart

genera.tor

capacitor C2B (fig. 28) for maximum output

on

the

output

generator

output

operation described

place

signal genera.tor

opcr~tion

indication on

signal generator

it

at

antenoa

capacitor C31A (fig. 31) for maximum

on

coil

output

Adjust

tuning coilL6

Adjust

·A·

1

a.r

.

e given m paragraphs 83 through

and

receiver

meter.

and

receiver

adjusting the in

output

a distance of approximately 1 foot

El. .

and

receiver sel to 7.8 me,

the

output

LS

(fig. 31) for

meter.

described

antenna

prot

ec111ve

1

ln~

uded as

'

meter. .

and

receiver

maximum

in

trimmer capac

at

2.1 me, following the

tuning

tuniag coil L9

tuning

tuning coil

•. A (fi

cover 3 g · ·

a.

reference

set

to 1,500 kc, adjust

set

to 600 kc, rock

CI3

output

(2) above.

lead to

(2) above:

coil

in

coil

in

set

to 4.2 me,

LlO

in

b above.

L8

b above.

an

L7

in

b above.

gu1

(.fig.

meter.

antenna

output

itor

C31B

(fig.

3l)

(fig.

31)

(fig. 31)

(.fig.

31)

)

4

'd

8

·

9z.

~he

30)

fot

3

feet

.

froll(

ad1ust

out~

a~JU~t

ns

mdi.

fi

( g.

gen~

9

6

at

·

at

ll.S

o.t

15.2

at

17.8

Specific

94

I

per

0

Output

I

converter capacitor B-bus.

2 Couple

r-f

3

4

ConnecUon

lead

of grid

and

generator

grid (pin 6)

signal

through

ground

output

of

VI.

generator

a

lead

.1-

µf

to

I

Input

quenga.J.:i

ID

400

455

1,

500

1,500

600kc

signal

percen

ted

cycles)

kc

_______

kc ______

kc

______

___ _

___

I

fre-

t

St

BC_--

BC

BC ________

Band

-----

________

______

__

1

Set

dial

600

kc

_______

1,500

kc ______

1,500

kc

___

600 kc*-----

nt

___

__

Adjust

T2

top

and

bot-

tom_

top

Tl

and

bot-

tom_

C2F

_____________

C2D

_____________

c1a

______________

I-f

alinement.

Oscillator

R-f

alinement.

Oscillator

ment.

Purpose

aJinement.

padder

aline-

5

6

•Indicat

es

adjustment

tb$t

requires

rocking

or

the

Repeat

ganged

operations

operations 2 and

tuning

capacitor.

2, 3,

and

3.

4.

\

Oper

--

- -

--

10

11

12

7

8

9

Couple

through whip nect post

Connection

generator

a 20-µµf c

antenna ground G.

tip

lead

output

apacitor

jack

.

terminal

to

quenga

7.8

lead

to

Con-

4.2

Repea

Repeat

3.9 me _______

2.1

Input

signal fre- I

(30 percent

m ulAled

me

at

.COO

cycleS)

me

_______

mc

___

____ / 4-8

t operations 7

ope

rati

_______

4-8

on 7.

2-4

Band

MC

___

MC ____

and

:\IC

____

MC

___

I

_ 7.8

4.2

8.

3.9

_

2.1

Set

dlAI

at

I

me _______

me•

______

me

_______

me*-

-----

Adjust

C40A ____________ C35A.

L18. Ll2.

C40B.

C35B.

Ll9.

Ll3.

Oscillator

ment.

Purpose

and

r-f

aline-

13

14

15

Repeat

9.6

\

operations

opera

me

___

tion

}

____ \ 31.

11

and

12.

l.

~L-----

1

9.6

mc

_______ 1

t;;·.*

16

17

18 17.8

11.8

15.2

me_~-----

me ___

___

me ______

25 M __

19 M ______ 15.2

16

M

____

__ 17.8

11.8

me

___

L22.

Ll6.*

______

______ L20.

L21.

Ll5.*

L14.*

'°

""

19 Replace chassis in cabinet.

20 One

turn

loop

broadcast loop antenna..

coupled loosely

--

21

22

Connect generator

3 feet of wire approximately

foot from whip antenna.

output

--

23

--

24

--

25

--

26

--

27

'Ind1cates adjustment

that

requlrt's rocking of the ganged tuning capacitor.

Reconnect

to

lead

to

1

whip antenna

600

kc_------

1,500 kc

7.8

4.2

3.9

2.1

9.6

11.8

15.2 me

17.8

______

me

_______

me ___

me

_______

me _______ me ___

me

______ ____

__________

____

------------

2-4

------------

____

31 M ___ 25

__

19

16M

tip

lead

BC

________

BC

________

4-8

MC

M ______

M ___

and

____

___

______

insert

loop antenna

600

kc.*------

1,500

kc ______

7.8 me ___

4.2me

. L5.

3.9

me ___

2.1

me

_______

9.6 me

_______

11.8 me

15.2 me ______

17.8 me ______

__

I

plug

Cl3

______________

C2B _____________

____

C31A.

C31B ____________

____

L6.

LIO.

____

L9. LS. L7.

into

loop

antenna

Alinement

antenna.

Alinement

socket.

of

ante

BC

nna.

loop

94

. Gene

a.

This quality tesL

pcrformed

o.nd

mmts

line source minut<'s

n.c.

95

.

a.

in

b.

be

of a

requirements

the

nocessn.ry skills. Rcpn.ircd

will furnish uniformly snt.isfactory

b.

The

nncl

.

Te

st

Equipment Requir

The

paragrnpb 62.

If

an

fn

bricu

(1)

Wrap 3 Lul'ns

spaced 3 Lurns per half inch. .

(2)

S?lder a 450-ohm

side

(:3)

Solder the cen

cnble conductor to the

o e s elded cable should be 30 µµf for

Section

IV.

ral

section is inlendt>cl us a

repaired

by

maintcnanc<' pcrsonnel

receiver should

and

batteries. Allow

mnke all

Radio

outlined in

br

measurements

opcmtcd

ed

equipment

RMA

Led

as

of

to

f

th

necd<'d for

In

addition,

test

loop is not, avltilable

follows (fig. :37): '

of

No. 20 wire

noninductive

the

loop. .

tcr

conductor

Lhe

free end of the 450-ohm

hi

oth

er

FIN

A L

guide

Rt>ccivcr

paragraphs

equipment

the

'"ith

for

Final

testing

l\

standard

of a 4-foot

'd

f h

s1

e o t e oop.

TESTING

to

be used in

R-520/URR.

96

with

adequate

meet

operation.

from

boLh

receiver to warm up

n l

ine

cletcrmi~ing

The

through

voltnge of

test

ing these

n.n

cxtcrnnJ

101

Testing

the

repaired

RMA

11

suitab

on

n 7U-inch diilrnoter

resistor

resistor,

1

recei~er

test

loop

le substitute

in

srries

length

t,ho

of

nnd

(The capacitance

4-f

oot

the

m1n[mum

•

~ay

equipment

require

Power

for

a

few

7

11

volts

is

~ted

is. required

may

form,

with

one

sl11elded

the. outer

th)

1

eng

be

-

.

96. Operation of

A complete check of

be mn.de in accord an

(par. 41). cc with

Controls

th

o.

97 · Sensitivity

The

readings

overall sensitivit f

in

paragraph

{.

7

98. Selectivity

Connect. the shielded

gcnomt,or conduct.or

loop

these conditions,

be

one-lPnth

generator a

:3-ohm

iack J3.

98

(center

to

the low sid

19%

inches

the

to 930 kc, modulated

output

Adjust

apart

the

meter

en

concl11c·Lo

signal

the signal

bl

')

on

~e.nt'

field inteers.'

g<'n"

(such as 0 Percent

. . L .0Js

operation

the

LI

0

le

1·

t'

I of Lhe R

oL

I he high side

ocu.tc

11811

' rMor l ignal

·rn

levct1~put

of

the

should

test, l

test Joop

at

Meter

znw

rece1

of

400 cyclc•s

equipment

.

receiver

MA

the

anu

paralleJ

.Y

at.

the receiver l

output. voltage.

01

·

50

ver

performanco

Lo

con l becklist

correspo

oop

t,o

th<'

gcnrrator,

and

each

other.

oop

Srt

t,hc

in µv/iv

TS-585/U)

at

the

output

c

nd

r-

f

the

receive~

l ie

and

connec

to

headshet

of t

should

to the

· al

signe

r

o~t

Ufnd~

wi

5

t

8

NOTE:

UV/METER=

SHIELDED CABLE 4

LON~J.

30

TO

APPROX

uvF

CA~CITY

GENERATOR

COAXIAL

6 FT

OUTPUT

10

450-0HM

(NON

INDUCTIVE)

RESISTOR

Figure S7. R

3 TURNS

WIRE,

TURNS

MA

test loop setup.

14------19£

NO.

WOUND

PER

20

6

INCH

------""

4

r----

I

-

-----,

I

'

I

•

I

-.

TM877-34

I

....j

rect>ivcr. setting

then

(6

db)

below difference ho

approximately

IO

timt>s

nnd

approximate

Rollo or Input

1

(0-db)

(reference) ____________________ _____________

2

(6-db

attenuation)

10

(20-db

attenuation).

100

(40-db

attenuation

Increase

(decibels).

930

kc

between

100 times

the

values

•• ___

the

signnl

until

the

high

6.38 kc. the

given

voltaico ol? rcs

.-----

__

••••

). ____

------

generator

Detune

the

receiver

nnd

low

Repeat

original

in

the

---------

onnnou

to

voltngo

-

________________ • - - - - - ---__

_____________

_____ _ • ______ - - ----- • -

output

signal

output gene1·a.tor

for .signal

settings.

following

nt rosonanco

~

____ ---

to

gener~to.r

ag~~

ge~er

The

table.

.---~:::

- - - - • • --__

twice its

.first above

50

1

ssettings

1

111

a.tor outputs

dwidths

.an

__-.-

•••

_

••

original

mw.

J.vemgo

width

and The

should

of

should

bsnd·

(kc)

6.38

15.32

27.

94

~----

99.

Image

a.

Any

signal t.ho i-f frequency.

Radio

above

from bro.aclcast osc1llo.Lor

s·

·1

,

im1

o.r

bands

~al.ol'

on

1£

tho receiver

b

d

an

, a

b

Tb

. . l e

~~7:.

a;he1t:;:;:i:g:

image

produce and

concsponding

frequencies.

c.

'l'o check

standard couple tho loop

Connect

----------

Ratio

Check

supei·hetorodyno recl.'i

that

is

removed

This interfering

Receiver

I · ·

y,

from below

t~ese

strong

da.

R-520/URR

the

desired

or

the

two

on

these

bands

unage

frequen

the

~ands

1s

tuned

.

signal

bT

i

i~y

of a repaired

tunes below

f~e~uency

frequenc:

a.

standa.rdo e vol

RMA

an

the

test as

output

t

~~o

out.put

lb

c Mtenuat.ion for

irno.

clos~iy

meter

---------

from

the

is

ver

desired

subject

---~~

is

input

signal

to

subject

is

signal frequency

cont

inu

ous

coverage

tunes

cy

above

interfer

ence

the

is

desired signal frequency,

the

desired signal

to "

on

••

14 -"

lS

the

·

si'g

.

.,

tag<'

'l'l

f

1

nn

rcquency

me

.

11

w1

rer

ratio

1

cause

,oivcr

to

is

determined

of the

at

the

desired frequenhc 'irnage ratios

t.

bl . d b 1

c a e m e

distinguish

each

.

0

log

ratio

on

the

broadcast

L~s

tho

~ignal

generator.

with Possible to

ceed as follows: Plug PL--55

(1)

(2)

Apply

Set

power

on

the

the signal

400 cycles. c,

Lo

broadcast

generator

tho

l'Cc

oiv . . .

bnnd.

01

to

and

set k ul d

600

~

------

. torference .

10

to

signal

called

image

when

desired

poss1ble

m·

input

of

the

to

the

mod

fr~q

the

frequenc!

opei;0t::use

b~nds,

on

bccauso

{requ

of

15

5

·

terf

erence.

bet"~eg

by

°:1ensur~~Jtnge

signal

lists

ow

severa

ban

ou.t~~

rece1ve

headsoL J

rece1ve1

ate

from

ncY by tmce

ue 6 frequency.

JJJlag interference

n is

on

the

the h-f

i nnl frequency.

8

g f

ur

o .

the

b-f

onCY·

t.he

on

en a

spread

oscil-

Thus,

19

dAo;red

.,..,.,..

tho

me

the image

a.t

the

y required to

t e t t

diJf

el'ent es

1

cl

connect the

' t cable and

1

p

antenna.

0

1

·o.ck J

30

dial

percent

3

to

.

600

Pro-

kc

at

a

M

100

Zenith Zenith_R-520 Service guide

Specifications and Main Features

Frequently Asked Questions

User Manual