Drake L4-B Service manual

IlllE

IF

CIIIEIII

_

PAGE

STANDARD

GENERAL

FRONT

DESCRIPTION------------------------

INStALLATION

A. B.

c.

D.

E. Jumper Connection

F.

G.

H.

I.

J.

K.

L.

M.

WARRANTY

SPECIFlCATIONS--·-------------_ 1

PANEL

Unpacking-------------------------Tube &

CONTROLS-----------------__ 1

INSTRUCTIONS-------------- 3

Chimney---------------------

(inside

front

cover)-

Location---------------------------

Power

Low

Antenna

Ground

Exciter Transmitting

VOX

Initial Viewing Angle

Requ~rements-----------------

Diagrams--~------

Pass

Filter--------------------

Requirements---------------

Requirements----------------

Requirements---------------

AGC-------------------

Relay--------------------------

Connection

Diagrams--------

Options--------------

1

2

3

4 4

4

5

6 6

6

7

8

TUNING

A.

B.

OPERATION------------------------------ll

A.

B.

c.

D.

E.

THEORY

SERVICE

A.

B.

c. Ordering

D~

PROCEDURE-----------~-----------

CW & RTTY--------------------------

88B &AM---------------------------10

CW & RTTY--------------------------ll 8SB-------------.·-----------------ll

AM---------------------------------ll

SWR

Calculation--------------------12

Accessory

OF

DA~--------------~------------14

Amplifier--------------------------t4

Power

Returning

Frequencies--------------l3

OPERATION--------------------13

Supply-----------------------16

Service

L..

4Bto

Parts-------------17

Pactory-----------17

ALIGNMBNT------------------------------18

A.

Input

B.

Meter

c.

Knob

D.

Wattmeter

Cotl

Adjuatment--------------18

Adjuatment-------------------18

Pointer

Alignment-------------19

Calibration--------------19

9

SCHEMATICS

for

L-4B

Amplifier

and

Power

Supply

(lalt

2

fold

out

pagel)

.

gENERAL SPECIFICATIONS

FREQUENCY 30

MHz

PlATE INPUT -

DRIVE

INPUT

OUTPUT IMPEDANCE -

exoeed

INTERMODUIATION DISTORTION PRODUCTS -

WATTMETER

+ 3

POWER REQUIREMENTS -

60

REQUIREMENTS

IMPEDANCE

watts).

cycles

DIMENSIONS - Amplifier

COVERAGE -Ham

may be

2:1.

30

covered

2000

ACCURACY'"

3000

watts

amperes.

Power Supply

with

watts

- 100

...

50

ohms.

Adjustable

forward,

230

13-1S/16'·

bands

some

PEP - SSB,

watts

pi-network

300

watts

± (5%

volts

6-3/4·

80

through

alteration

1000

PEP

- SSB, 7S

forward

of

reading + 30

50 - 60

W x

7-1/S"

W x

7-7/8"

watts

cycles

10

of

input

watts

matches

In

excess

and

reflected,

H x

meters.

circuit.

OC

on

15

amperes,

14-5/16"

II'·

CW,

~W,

50

ohm

of

-33

.±.

watts).

D.

All

frequencies

AM

and

AM

and

Une

DB

(5%

of

or

OJ

RTrY.

RTTY.

with

reading

115

volts

SWR

3.5

not

50 -

to

WEIGHT

TUBE

FRONT PANEL CONTROLS ON-OFF

...

Amplifier

COMPLEMENT -

...

Rocker

32

SWitch

Ibs;

Two

Power

3-S00Z

SSB-CW/l'UNE - Rocker SWitch

ation.

BA.ND -Switch

PIATE

resonance

METER -Switch

reflected

AGe/STANDBY

that

RFAR

ing

mitting

(for

and

RF

allows

JACKS -Power

on

L-48

AGe

connecting

LOAD and

loading

power

PUSH

the

with

to

exciter),

L-4B

selects

...

Tuning

selects

on

L-48

exciter

to

desired

adjust

on

all

monitoring

the

lower

...

Transmitting

to

remain

(connects

VOX

contacts),

RF

input

an

antenna)

Supply

or

changes

ham

pi*-network

bands.

either

meter.

on

while

L-4B

(for

•

43

Two

8802/3-S00Z

plate

bands

AGe

(See

grid

threshold

operating

to

power

transmitting

connecting

lbs.

voltage

Frequency

capacitors

current.

adjustment

with

supply),

AGe

to

exciter

or

Two 8163

for

different

Coverage)

in

tank

circuit

plate

voltage,

and

the

exciter

high

voltage,

(for connecting

RF

output),

or

Two

3-400Z.

modes

of

•

for

proper

forward

push-pull

only.

VOX (for tum-

trans-

RF

output

oper-

or

switch

1

ME'lERS Power (switch

Plate

Current,

selected>.

Grid

Current/Plate

Voltage/Forward

Power/Reflected

POWER

DESCRIPl'ION

The R L

ssa,

through

alteration

The triodes

feedback

A

transmitting

power

through to

cutoff,

The internal current,

SUPPLY

DRAKE

and

1000

10

meters.

of

L-4B

output

uses

in a Class B grounded

for

without

when

eliminating

tubes

blower.

plate

controls

watt

the

input

two

lower

AGe

peak

the

L-4B

are

Two

voltage,

Model

DC.

All

circUit.

3-S00Z odd

circuit

clipping.

is

unwanted

forced-air

taut-band

- Two

L-4B

CW,

frequencies

order

turned

circuit

Linear

AM

or

two

grid

distortion

controls

An

off.

heat

cooled

suspension

and

relative

breaker

Amplifier

and

RTTY

3.5

8802/3-S00Z

circuit

the

internal

A

and

RF

operation

to

30

configuration

products.

exciter

changeover

pair

of

diode

by

a.

very

meters

output

reset

offers

MHz

or

two

gain

relay

noise

quiet

power.

buttons.

continuous

covering

may

be

8163

that

to

allow

relay

contacts

when

low

indicate

2000

the

covered

or

two

3-400Z

utilizes

the

highest

feeds

receiving.

velocity,

plate

bias

current,

the

watts

ham

with

RF

antenna

output

high

PEP-

bands

some

negative

average

80

re-

zero

tubes

volume

grid

bias

The

separate

excellent

solid

dynamic

state

and

power

static

supply

voltage

.

Do

amplifier

removed

requires

regulation.

not

with

because

voltage interlock

the power

8 +

supply

and

no

warm up

turn

the

on

top

the

cover

the

shorts

will

damage

components.

period

L-4

high

out

and

provides

2

INSTALlATION INSTRUCTIONS

The L-4B ous

electrical

minal

should

voltage

age

terminal

installed

has

while

never

terminal

and

been

the

be

should

serviced

·followed expl1c

A

Carefully their

Should the

Fill

tive

Save

Inspect

not

UNPACKING

o

packing

any

full

extent

out

and

o

the

overlooked

remove

cartons

damage be

mail

packing

designed

shock.

L-4B

attempted

should

be

itly

•

your

of

the

enclosed

material,

material

the

cables

incorporating

However,

Is

turned

for

be

disconnected

connected

in

complete

on.

any

it

reason.

first.

L-4B Amplifier,

and

examine them

apparent,

notify

damage.

registration

you

may

closely

or

other

several1nter-Iocks

Is

possible

This

Is a potentially last

The L-4B

safety

if

tubes

closely

the

qard

need

'it

before

hardware

to

disconnect

When

disassembling

and

upon

and

the

instructions

and

chimneys,

for

signs

delivering

so

that

later

putting

for

it

shipped

to

the

dangerous

reassembly

its

power

in

and

of

shipping

carrier

your

immediately,

warranty

reshipment

away

with

to

the

be

L-48.

prevent

high

situation

the

supply

this

power

or

storage.

sure

danger-

voltage

L-4B,

high

can

manual

supply

damage.

-will be

you

ter-

and

the

high

volt-

be

are

from

stating

effec-

have

B

Tubes

Data,

The adjacent ling base

The handling

.

pushing

cleared

both neys. the

sitic

!!!!.S!

be

TUBE

o

and

chimneys

Amplifier, Removing Top Cover) •

tubes

are

pins,

the

tubes,

pins

may

chimneys

them

t~,yo

when

chimneys

The

screw

at

choke

from

the

connected minum machine this

screw

replacing

when

the

AND

CffiMNEY

installed

face

push

break.

are

installed

because

clips

the

are

outward

chimney

flush

parasitic

the

top

to

the

plate

supporting

to

the

screw

connecting

top

cover,

can

be

first

In

either

straight

they

with

chokes

of

the

connector.

top

of

already

the

INSTALlATION

installed

Notice

o

SOCket, down

after

are

to

the

fragile.

with

is

lowered

the

chassis

are

installed

pla~

leads.

the

plate

in

the

parasitic

connector

The

the

amplifier

after

that the insert

tubes

the

onto

The

free

RF

top

can

removing

base

ends

The

chimney

and

parasitic

choke

of

them

and

extra

chimneys

the

chassis.

that

after

and

ends

with

the

and

until

no

the

use

choke

of

both

the

plate

tubes

chokes: a snug

be

connected

the

top

3,

the

amplifier

do

not

care

~ust

should

the

opposite

Check

clips

and

this

screw

coil

parasitic

1/4

choke.

fit

for

cover

with

(see

no

case.

rock

the

be

exercised

be

installed

clips

to

be

are

inside

chimneys.

to

fasten

should

chokes

- 20 round

Do

not

is

adequate.

operation.

Service

immediately

When

tubes

instal-

or

the

while

by

will

be

sure

that

of

the

chim-

Remove

the

para-

hang

can

head

down-

then

alu-

overtighten

After

3

c.

In

considerations

be

cases

radiators

fier

overheating and

blower

LOCATION

general,

taken

to

allow

or

power

should

will

the

insure

heating

may

not

be

location

which

that

adequate

units

supply

blocked

cases

resulto The

be

placed

of

must

space

air

closer

and

the

L-4B

be

given

is

allowed

circulation.

should

with

overheating

be

books,

back

than 1 inch

is

not

to

insure

around

avoided.

papers

of

the

amplifier

of

critical,

optimum

the

Extremely

Do not

or

other

from a

the

ampUfier

however,

performance. amplifier hot

locations,

cover

pieces

case

wall

must or

tubes

the

there

and

power

tops

or

equipment

not

be

air

inlet

may

occur.

are

certain

Care

such

of

obstructed

should

supply

as

the

for

near

ampli-

or

the

D.

The L-4B from

plug operated L-4B. The L-4B

230

volt

be

other

stances

ductors

E.

Below

jumpers

serious

POWER REQUIREMENTS

is

included

either

and

VAC 0 It

15 amp

fused

equipment

JUMPER

socket from

for 30

operate

are

pictorials

in

damage

115

either

1s

or

not

both

greater,

with

its

VAC

or

230

VAC

configurations

115

volts

is

shipped

highly amps

should

the

large

CONNECTION

the

to

recommended

circuit.

and

the

be

operated

L-4B from a 115

enough

of

jumper

amplifier

the

L-4B

own

separate

SO

- 60

_for

230

or

230

volts, a line

from

the

factory

that

If

a 115 V

circuit

to

DIAGRAMS

connections

and

components

115

conductors

from

volt

safely

VOLT OPERATION

carry

power

cycles.

volt

service,

the

circuit

this

lighting

for

supply

may

Because

with

L-4B

should

circuit.

this

load.

both

must

result.

supply

and

because

plug

is jumpers be

operated

Is

all

that

not

Do

circuit

230 V

be

connected

which

of

not connected

not

because

and

can

the

large

furnished

from

is

available,

be

less

under

115 V

be

operated

variety

the

L-4B

to

operate

its

own 230

than

any

the

circuit

operation.

as

shown or

of

can

with

the

it

should

il0

and

circum"

con-

be

on

no

The

o

Amplifier

4

Power

Supply

o

230

VOLT

OPERATION

F• LOW

The

L-48 second Because feed

a

suitable

harmonic

of

line

Amplifier

PASS

has

been

the

that

is

low

FILTER

designed

content

posSibiUty

resonant

pass

filter

in

accordance

Is

attenuated

that

you

may

at a harmonic

such

as

our

Power

with

good

from

the

fundamental

be

using a multiband

frequency,

Model

TV-IOOO-LP

Supply

engineering

it

is

highly

be

practices

by

at

least

antenna

recommended

used

with

or

the

35

have

and

dB.

a

that

L-4B.

G.

The

quency

The

should meet

With

to

Most

ANTENNA

L-48

and

nominal

never

these

S~

ohm

an

appropriate antenna

practical.antennas

exceeds such

as

our

maximum

CAUTION:

H.

GROUND

REQUIREMENTS

has

been

having

output

exceed

requirements,

coax.

2:1.

MN-2000

power

designed approximate

impedance

For

this

transfer

NEVER NEcTING IT TO SUFFICIENT

MAY

RESULT.

REQUIREMENTS

2:1.

the

For a

detailed

book.

exhibit

reason

which

into

ATTEMPT

for

use

impedances

of

the

Although

simplest

discussion

an

we

recommend

will

allow

the

antenna.

TO

AN

POWER

With

antennas

Within

L-4B

there

is

are

is a one-half

SWR

range

the

L-48

OPERATE

ANTENNA

HANDLING

resonant the

50

ohms

many

on

antennas,

types

over

using

to

an work

THE

OR 50

CAPACITY

at

the

operating

limits

and

(1/2)

of

the

of

antennas

wave

we

25

to

SWR

of

dipole

suggest

100

this

which

a complete amateur

antenna

into

L--48 WITHOUT

OHM

matching network

a 50 ohm

FIRST

DUMMY LOAD

OR

SERIOUS

fre-

ohms.

load

will

center

referring

band

load

that

for

CON-

OF

DAMAGE

fed

The

a

ground

L-4B

should

strap

be

as

possible

attached

to

for

a

best

good

results.

earth

5

ground

A

binding

through

post

as

short

is

provided

and

as

on

large

the

rear

of

the

It

Is

always

gether

all

of

and

the

amplifier

L-4B

chassis

a good

ground

equipment

chassis.

idea

them

in

for

to

at

your

this

connect

one

point

station

purpose.

the

chassis'

to

avoid

be

connected

of-all

ground

together

associated

loops.

and

We

recommend

grounded

equipment

that

at

the

to-

L-48

I.

To to

RP mitters

EXCITER REoUIREMENTS

operate

deliver

power

allowed L-48

A

amplifier

J•

TRANSMITTING

jack

of

a

transmitting power supplied

Power A

connector

and a

K.

transmitting

VOX

the

L-48

to

the

on

CW,

all

have

on

8SB,

as

on

the

rear

level

can

with a cable

Supply

which

is

available

RElAY

at

the

L-48

adequate

CW.

AM

input

RrTYand

Rl'T~

practical

AGe

of

the

AGe

be

voltage

run

to

up

terminates

AGe

connector

maximum

legallnput,

connector,

TUNE. The

power

L-48

to

connect

to

and

AM.

so

that

amplifier

which

2000

in

drive

the

controls

watts

this

the

The

jack

particular

for AC-3 Power

from

100

watts

TR-3,

the

exciter

coax

and

is

proVided

PEP

to

Supplies

the

transmitter

it

PEP-SSB

TR-4.

L-4B

to

should

ground

the

gain

without

a

similar

transmitter

that

will

be

r-4/r-4X/l'-4XB

the

strap

for

connection

of

peak

jack

brings that

required

RP

maximum

be

placed

will

of

power

legal

as

be

to

the

exciter

clipping•.The

on

our

Model

the

AC-4

out

the

AC-3

the

exciter

and

15

Trans-

input

close

short.

the

exciter

so

that

L-48

AC-4

is

powering.

vox

c·ontacts

is

powering.

watts

to

the

any

is

A

two

pair

of

thus connect

ates

Some contacts necessary

.

position.

the

L-48

that

the"

Jack

nonnally

tum

on

this

in

the

exciters

made

to

With

plate

L-48

on

the

open

the

L-4B

Jack

to a similar

particular

(except

available

plug

the

current

plate

current

rear

of

relay

at

contacts

the

transmitter

TR-3,

to

key a linear

two

exciter

to

1n

read

Is

the

L-48

same

Jack

time.

on

the

TR-4.

connector

standby, up

scale,

zero.

amplifier

in

the

The L-4B

our

Model

AC-4

Is

exciter

is

powering.

prOVided

which

is

supplied

AC-4

close

Power

T-4/r-4X/1':"4XB) ground

amplifier.

tnto

the

if

plugging

reverse

6

For

L-48

in

the

these

vox

the

vox

connector

socket

vox

for

connection

on

transmit

with a cable

Supply

one

of

the

exciters

in

connector

1n

which

extra

it

will

the

correct

causes

its

socket

to

a

and

to

termin-

relay

be

so

T

.....

3141

T-41T-4X/T-4)(8

fiG. I

INITIAL

CONNECTING

CONNECTION

THE

TR-3/TR-4/T-4/T"4.

AND

AC-4

DIAGRAMS

L-48

TO

THE

L48 UNEAR

AUPUFIER

•

<t

....

AGe

e.....

L-48

L-4PS

<t

•

7

M.

VIEWING ANGLE OPTIONS

STANDARD

OPTION

OPTION.

15:1/..,

__

--

INVERTED FRONT

FEET REMOVED

# I

2

SCREW

FE

FEET

FROM

ET

REMOVED

REAR

MOUNTED

OF

BASE

REAt;

tt

STUO

SUPPLIED

.Oa24

8

WITH

x

S/8

UNIT

LONe

TUNING PROCEDURE

WARNING

-

Be

dummy

the

used.

For al!.

ing

tuned

BY

when

After

STANDBY switch)

SSB

Some of unplugging control

switch

AGO

it

and up

push

driving

the

modes

switch

of

with

on

CW

the

exciter has

push

to

CW-TUNE

operation

exciters

operationo During

the

fully

off

on

counter-clockwise

AGe

these

sure

that

the

load

and

power

supply

(See 115 V

operation,

the

plate

into

in.

L-4B

the

The

since

voltage antenna

exciter

been

switch

out

position.

should

utilize

be

off.

transmitting tune

transmitting

in

TUNE,

transmitters.

L..

that

the

tuned

on

the

up,

AGe

CW,

4B

is

connected

the

proper

and

linear

and

230 V Jumper

L-4B

is

switch

connected should antenna

up,

turn

L-4B

The

and

red

AGe,

transmitting

connector,

0 The

and

TR-3,

AM

to

a

SO

Jumpers

amplifier

have

for

Connections,

tWled up With a

in

CW-TUNE

to

the

L-4B

be

checked

connected

the

exciter

put

light

that

the

to

plate indicates

sometimes.called

AGC

will

or

turning

TR-4,

modes;

T-4/r-4X/I'-4XB

it

is

unnecessary

ohm

antenna

been

the

line

single

position.

by

pushing

be

sure

the

L-4B

standby

voltage

high

ALe,.

have

to

the

AGe/STANDBY

or

installed

voltage

that

Page 4 and

RF

frequency

The

exciter

the

that

it

is

may

not

and

pull

switch

plate

during

be

defeated

Tra

to

externally

50

ohm

in

BOTH

is

to

be

5).

driV-

may

AGe/STAND-

tuned

be

(red

voltage

all

50

the

rocker

modes

by

up

ohms.

AGe/

for

either

push

nsmitters

defeat

be

A.

PRESET THE CONTROLS

1.

2

3.

4.

5.

6.

Turn amps

load until

voltage

for 1000

.

is input

forward

CW,

Plate Band

0

Meter Load Plate

RTTY

voltage

switch

fully

control

Turn AGe/STANDBY

on

the

exciter

and

tune

and

plate

maximum

a graph.

watts

operating

cannot

RF

at

be

watts

switch

to

counter-clockwise

in

and

the

plate controls RF

output

is

supplied

DC

plate

or

under

obtained

at

maximum

AS

FOLLOWS:

desired

3000

the

arc

increase

control

while

occurs

input

the

beoause

in

CW-TUNE.

band.

watts

forward.

provided

push

control

the

for a dip

increasing

at

.565

below

which

power

maximum

of

exciter

(CCW)

for

fully

exoiter

the

plate

correlates

and

should

legal

low

exciter

Power.

on

the

number

the

desired

counter-clockwise

in

output

plate

exciter

current.

amps.

while

power

Because

plate

be

used

Input

power.-

power,

zero.

band.

not

in

voltage

to

In

tune

(CCW).

exceeding

Alternately

small

of

increments

variations

and

be

sure

that

case

maximum

the

L-4B for maximum

.4

adjust

plate

the

plate

the

in

line

current

L~4B

legal

9

PLATE

VOLTAGB

2000

1900

1800

1700

1600

1500

\

.500

1000

Watts

D.C.

Voltage

VS

and

Plate

\

Plate

Input

Ampere.

\

1\

\

,

\

,

\

,

\

r\.

"

\

.550

.600

.650

'"

.700

B.

PRESET THE CONTROLS

1.

2• Band

3 •

4.

5 •

6.

7.

Turn

amps and tune the

exciter

plate

CWTent the

small

essary

8SB,

Plate

Meter

Load

Plate

Tum

Substitute

tubes

on

the

power,

amps

with

load

control.

adj

ustments

to

obtain

AM

voltage

switch

fully

control

AGC/STANDBY

have

exciter

switch

to

desired

to

grid

counter-clockwise

1n

the

250

rna

been

supplied.

and

plate

maintain

is

reached.

the

plate

control

The L-4B

of

the

.565

plate

AS

FOLLOWS:

in

CW-TUNE

band.

current.

arc

provided

push

grid

current

increase

control

220

rna

Leave

and

will

driving

amps

(CCW)

control

the

for

a

of

grid

the

exciter

then

now

power,

with

PlATE

position.

on

for

the

fully

in

succeeding

exciter

dip

in

current

power

bring

be

very

and

220

rna

AMPERES

the

number

desired

zero.

band.

counter-clockw1se

text

if

Amperex

output

plate

the

close

plate

current.

with

at

grid

while

the

load

this

current

to

being

and

load

current

not

While

level

tuned

controls

at

(COW).

8802/3-500Z

exceeding

increasing the

control

and

back

untU

re-dlp

to

up

and

will

resonance.

220

.4

.565

the

rna

only

be

plate

plate with

nec-

The forward power meter

plate current

power

current.

tWle

while

the

dip,

and

the

still

maintaining

In

case

.565

plate

L-4B for maximum

is

a more sensitive indication

of

plate control should be adjusted for

the

relationship

amps

forward

cannot

RF

watts

be

reached

at

of

.565

because

maximum

plate

exciter

10

plate

amps

of

tank resonance

maximum

to

low

forwald

220' ma

exclter

power.

than

grid

power.

OPERATION

In

the

following

that

the

L-4B

as

described

infonnation

and

its

in

the

Tuning

exciter

concerning

have

be.en

Procedure.

operation

tuned

up

on

various

the

desired

modes

operating

I

it

is

assumed

frequency

While plates

life that the 1s

periods

several

A.

For tion.

product

For

light

old

With

1s

exciter

with

the

you

clockwise

desire.

be

the

relationship

voice

meter

legal

transmitting

may

show a dull

of

the

tubes.

L-4B

tuned

of

be

up

properly.

transmitting,

minutes

ew,

CW

With

8SB

that

must

the

adjusted

the

RTTY

and

RTI'Y

the

of

plate

operation

indicates

be

set

plate

by

either

exciter

AGC!STANDBYpush

desire

to

run

until

Return

set

once

L-4B

on

should

of

operating between

input

allowed

exceeded.

with

the

L-4B

red

color.

If

the

plates

checked

to

detennine

The L-4B

but

should

to

allow

operation

exciter

voltage

the

high

before

voltage

the

on

and

plate

using

switch

final

the

and

plate

voltage

the

applying a large

an

oscillator

adjusted

for

maximum

control

less

than 2 kilowatts

the

single

the

plate

each

be

.565

band.

checked

plate

conditions,

.300

to

and

tone

voltage

amps

.400

this

When

for

the

amps.

level

over

extended

This

Is

display a very

that

should

be

not

left

amplifier

plate

the

voltage

key

depressed,

current

switch

voltage

should

L-4B0

in

OW-TUNE

single

or

by

whistling

audio

output.

clockWise

PEP,

plate

to

eXciter

current

SWitch

making

tank

220 ma

0400

should

to

large

should

amps

be

periods

normal

and

bright

it

1s

not

be

turned

on

standby

tubes

to

switch

adjust

is

at

or

under

should

be

on.

position

tone

into

a

single

With

until

the

tum

the

decreases

SSB. The

changes

resonance

grid

current

be

adjusted

of

plate

reached

of

time,

does

orange

being

off

with

cool

should

not

color

over-driven

immediately

zero

down.

be

in

the

drive

maximum

in

8SB

position

The

transmitting

the

transmitting

the

microphone

tone

into

this

single

plate

current

AGe/STANDBY

to

the

power

AGO

threshold

in

frequency

while

on

still

CW

..TUNE. Under normal

to

run

current

only

occasionally

the

final

detract

it

from

is

advised

and

after

plate

amps

CW-TUNE

level

legal

input

and

AGe

input

the

microphone

tone

applied,

Is

.0580 amps., U

push

level

needs

Within a

maintaining

the

L..

48

is

the

maximuml.

and

amplifier

the

that

it

long

for

posi

until

the

power

the

red

thresh-

thre~lhold

of

the turn

control

you

only

to

band,

the

plate

never

..

~

If

should

c.

. For

light

the

AM

exciter

be

monitored

aM-

operation

that

indicates

has

no

provisions

with

the

plate

high

for

an

oscilloscope

voltage

plate

voltage

transmitting

to·check

switch

should

11

AGC,

be

for

be

on.

the

peak

in

The

output

SSB

L-4B

from

clipping.

position

works

the

and

quite

L-4E~

the

red

favor"

ably

with

controlled

TR-4,

an

modulated

.

watts

D.

T-4/r-4X/r-4XB

oscilloscope

OC

SWR

the

TR-3,

carrier

AM

transmitter,

input

CALCUIATION

TR-4,

modulation. Transmitting

to

check

With

an

T-4/T-4X/T-4XB on

AM

AGe

Transmitters and the L-4B

for

peak

the

unmodulated

clipping.

exciter

carrier.

should

If

the

be

since

is

not

used

output

L-4B

adjusted

these

on

should Is

to

be

to

run

transmitters

AM

with

the

be

monitored

used

with

the

L-4B

use

TR-3,

with

a 100 %

at

500

The SWR and

reflected

plied

scales

the

dicates

using degree of the delivered forward

with

center

only

the

3000

meter

at

of

the

power

the

L-4B.

the

L-4B

scale

forward

the

accuracy

watt

tQ-03000

to

the

power.

load

connected

readings

forward and

at

the

and

reflected

exciter.

can

scale.

watts

load

from

The

calculator

intersection

power

For

measuring

be

obtained

When

or

the

can

be

determined

fOIWlID

-

1.-

7.

to

the

L-4B

the

L-4B

1s

used

reflected

of

the

at

all the

by

using

returning

wattmeter

can

wattmeter

by

meter

straight

times~

exciter

the

L-4B

may be

by

subtracting

V.I.

....

1.05

1.1

1.2

1.1

1.4

1.5

be

determined

and

laying a straight-edge

readings

so

R.F.

300

into

damaged.

and

line.

that

output

watt

service,

the

IBUCIII

1.0

2..

1.0

5..

by

the

SWR

reading

The

L-4B

SWR

can

power a

forward

be

The amount

reflected

7.0

using

calculator

wattmeter

be

scale

sure

the

forward

sup-

across

the

VSWR

in-

calculated

higher

instead

to

return

of

RF

power

power from

the

on

the

-

Lay Itraighteclge .

on

appropliate forwanI

.........

v.s.

S.W.R.

ntacIi

w.

I

..

on c scale.

CALCULATOR

12

....

reaeI

II

•

50

71

1.

E.

OPERATION

ON

ACCESSORY

FREQUENCIES

The

input amateur values

of

THEORY OF

The

50 ohm

each

ganged obtained C30,

coils

bands.

the

band

to

by

C31,

Bandsw1tcb

may

be

For

frequencies

capacitors

OPERATION

input

which

the

is

bandswitch

slightly

C32

and

80

40

20

15

10

re-tuned

ill

the

matched

selected

82.

raising

C37.

Position

for

frequencies

far

removed,

input

to

by

circuit.

the

Negative

the

grids

final

input

above

Frequency

3.2

5.0

10.5

15.5

22

moderately

it

may be

amplifier

SWitch

feedback

ground

in

-

..

necessary

cathodes

Sla,

in

SIb.

the

with

MHz

5.0

10.5

15.5

22

30

removed

to

by a pi-network

The

input

L-4B

amplifier

capacitors

from

change

C23,

the

switch

is

C29,

on

1s

Wh~n

exceeds

conducts

input

A

1s

The

consisting

The take to

and

200 ma movement

the

appears

positive

applied

plate

directional

the

swn

indicate

RI9

rectify,

nega~ive

positive

and

a

at

voltage from

to

the

circuit

of

C46,

and

forward

going

bias

negative

the

transmitting

the

cathode

is

matched

L6,

L7,

wattmeter

difference

and

renected

filter,

to

and

indicate

peak

voltage

set

RF

by

resistor

dUring

to

C48,

consists

of

multiply

forward

voltage

R3,

the

proportional

AGe

output

divider,

standby

the

50 ohm

C49, C52,

basically

the

transmission

RF

power.

the

and

from

the

capacitor

transmitting

to

the

connector.

R9, RIO,

which

lower

reflected

cuts

output

C53

of

L8,

line

03, 04,

front

by

and

AGC

RF

RII

off

the

eS6.

C54,

phase

C59,

panel

RF

power.

divider

threshold

signal

the

in

plate

the

applied

adjustable

CSs

voltages

C60,

meter

power

current.

and

R1S,

M2's

024,

C25

control,

to

the

supply

pi-network

CS7.

and

which

currents

R17,

basic

01

R18,

13

SERVICE

DATA

WARNIN~

-

EXTREME

ANY ADJUSTMENTS INSIDE EITHER THE AMPLIFIER OR POWER

SUPPLY.

UNPLUG THE POWER SUPPLY FROM THE POWER

THE POWER CONNECTOR

THE

MINAL

A.

1.

2• Removing

AMPUFIER

Removing After cover

on

After

completely

both

completely

bottom three

can

cover

screws

3• B!!moving

front

The

of

the

amplifier.

the

six

the

leads

careful

ment

to

will

1;-4B,

top

cover

then

sides

bottom

can

on

front

panel

screws

of

the

note

be

made easiar.

CAUTION

BEFORE

AND lAST; DISCONNECT THE

FROM

THE

SHOULD

MAKING

AMPUFIER.

BE

ANY

ADJUSTMENTS

GOING

-

disconnecting

be

safely

of

the

amplifier.

cover

-

discoIUlecting

then

be

both

sides

panel

can

that

the

be

The

hold

front

tenninals

removed

knobs

panellndicator

removed

safely

the

of

the

should

front

that

L-4B

by

taking

L-4B

removed

amplifier.

only

after

be

panel

lights

each

from

removed

to

lamp

EXERCISED

FROM THE POWER SUPPLY TO

all

out

the

all

by

taking

first

removing

chassis.

from

was

WHENEVER

TO

HIGH

sources

top

row

source

out

s

the

followed

Finally,

their

te~inal

connected

THE LINE,

VOLTAGE

of

power,

of

three

of

power,

bottom

top

and

by

striP.

to

so

MAKING

L-4B

UNPLUG

TER-

the

screws

the

row

of

bottom

removal

unsolder

Be

replace-

top

of

4.

Cleaning

Since of

dust

be

governed environment the remove

If

compre

used

5• Tube

If

it

should

COil

replaced

6.

Input

The

If

the

amplifier

the

amplifier

which

by

1s.

amplifier

the

top

ssed

to

brush

replacement

becomes

be

used

Adjustment,

by

the

Switch

input

belt

switch

ever

compartment -

compartment

must

how

be

many

When

should

and

air

the

necessary

Drive

be

oottom

is

not

amplifier

-

or

it

may

Page

same

Belt

is

Unked

needs

is

removed

hours

the

periodically.

the

blower

cleaned.

covers

available,

clean.

to

replace

be

neoes

18).

brand

Replacement

of

to

If

one

tube

the

replacement,

forced-air

L-4B

wheel

The and

a

the

sary

as

is

accumulates

best

blow

soft

bristled

tubes

to

tune

tube

needs

originally

-

way

bandswitch

it

should

14

cooled, The

frequency

operated,

to

clean

the

dust

1

in

the

input

replacement,

supplied.

by

two

be

done

it

will

and

a

large

the

out

with

inch

L-4B,

colIs

pulleys

in

the

collect

of

cleaning

by

how

amount

amplifier

particles

clean

of

is

compressed

paint

the

same (See

it

and

brush

brand

Input

should

a bead

can

be

following manner.

will

its

dust,

to

air.

be

belt.

6.

Input

Set

Switch

the

bandswitch amplifier that

is

on

shaft been that

and

removed,

the

input

insertion connecting

same two check

screws,

time

switch

that

replace

Drive Belt

and

remove

the

bandswitch

remove

switch

forces.

both

0 The

sha

fts.

the

input

to

only

great

Set the

pulleys,

copper

Before

the

Replacement

20

meters

the

front

shaft

the

pulley

caution

rotors

are

input

install

sleeve

tightening

switch

front

is

panel

and

panel.

and

on

in

replacing

aligned

switch

the

on

still

and

(Continued)

remove

Loosen

remove

this

shaft.

this

and

on

pulleys

the

chain

the

setscrews on

aligned

amplifier

the

are

20

meters

on

should

for 20

top

the

setscrews

pulley.

If

the

shaft

not

damaged

their

be

meters.

covers.

and

bottom

Hold

input

~ust

and

be

with

respective

midway

the

Tighten

covers

in

the

pulley

the

input

switch

taken

..

by

the

new

shaft

to

shaft

insure

shafts

between

ba.ndswitch

the

of

the

switch

has

belt

at

the

thE~

pulley,

set

7.

8.

L-4B

CW"

8SB

Lubrication The

blower

weight

Trouble

Careful

maintenance

some

problem occurs, direct detail.

settings, number

00

NOT RETURN EQUIPMENT

of

blower

motor

petroleum

shooting

- "

consideration

problems

will

we

suggest

to

our

CUsrOMER

Include

full

assc;>ciated

of

the·

L-4B.

should

oil

arise

that

information

AUTHORIZATION.

PlATE VOLTAGE

Tune

1900

2600

volts volts

motor

in

has

to

-

be

lubricated

the

front

and

rear

been

a minimum.

which

you

SERVICE DEPARTMENT

given

cannot

either

return

concerning

equipment,

No No

Load Load

antenna

TO

THE FACTORY WITHOUR PRIOR

1760

2400

once a year

bearing

to

the

design However, be

cured

your

by

unit

external

and

be

volts

with

several

oiler

it

tubes.

of

the

Is

quite

tube

substitution.

to

your

describing

connections,

sure

to

indicate

@

.565

@

.800

L..

4B

possible

dealer,

your

amps amps

drops

to

of

keep

that

If

or

write

problem i,n

control

the

serial

10

this

L-4B

Amperex Amperex

IDUNG

8802/3-S00Z 8163

Eimac 3-40QZ

Eimac

All

ting

All age

3-500Z

tubes

the

above

full

voltages

variations.

PlATE

tubes tube

tube

are

legal

and

CURRENT

s

directly

limit

currents

interchangeable

for

amateur

listed

above

CW-Tune

.100

.110

.170

service.

bear a 10%

15

amps

in

the

L..

4B

and

tolerance

SSB

.160

.170

.260

are

for

amps amps

amps

capable

tube

and

of

line

opera-

volt-

B.

.

POWER

SUPPLY

1.

2• Removing

Circuit There the

breaker

are

circuit

breakers

the

circuit

an

investigation

After

the

bottom

completely

power

of

two

breakers

triP.

breakers

bottom

supply

the

3• Removing top

The

top

cover

4.

moved. the remaining

Troubleshooting

Careful

to

keep

fails

After

barrier

strip

screws

consideration

maintenance

to

function,

necessary.

in

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