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

3

4
4

4

5

5

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

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

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

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

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

the

overlooked

remove

cartons

damage be

mail

packing

packing

designed

shock.

L-4B

attempted

should

be

itly

•

your

of

the

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

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

Pin

ends

The

chimney

and

parasitic

choke

of

of

them

and

extra

chimneys

the

chassis.

that

after

and

ends

with

the

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

pin

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

to

allow

or

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

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

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

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

o

Amplifier

4

Power

Supply

o

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

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"

pin

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

the

current

plate

current

rear

of

relay

at

contacts

the

transmitter

TR-3,

to

key a linear

two

pin

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