Collins 300G Instruction Book

INSTRUCTION

FOR

3oäG

BOOK

AM

BROADCAST

TRANSMITTER

COLLINS

CEDAR

RADIO

RAPIDS,

COMPANY

IOWA

Y

WARNING

r

OPERATION

VIOLVES

ARE

SONNEL

ALL

THE`;L7'SE'O'

DANGERO.USITO

SHOULD tT,

THE SAFETY

NOT CHANGE

MENTS

INSIDE

VOLTAGE

UPON DOOR
BUT ALWAYS

MENT

SUPPLY

AND

CIRCUIT.

GROUND CIRCUITS

THEM.

Since the .uses

to

ous
eration

by

-- fires must

í

personnel

human.

of

these

the radio .transmitting

instructions,

be carefully

during the adjustment

the equipment.

The

major

metal

cabinet enclosures,

which

are

generally fitted

switches which

the cabinets

Interlocks

panels within

will not

cause interlocks

mfr..,

OF

, IS g.QUIFMENT;-

I

t.TtES LISTED

TUBES

.EQUIPMENT

SUPPLY

SWITCHES

SHUT DOWN

OPEN MAIN

ALWAYS

of iìigh vdliáges

life is.

necessary

certain

-

portions

of the

remove

when

.ácces5 doors

are also

provided on

the cabinets.

;.

atiN.

I.íIFE'

ON. DO NOT

PRIOR

sm.t

observed

provided

dangerous

Other panels,

to function

LTÄGES

E

Or

'

L MMES

.ATING P'ER.-

OBSERVE

BELOW.

OR MAKE ADJUST-

-

WITH

DEPEND

FOR

PROTECTION

POWER

SWITCH IN

DISCHARGE

TO TOUCHING

'wkriëh

to the

are

successful

equipment

precautionary

the

by

and

equipment

operating

operation

are within

with access doors

with

safety

interlock

voltages

are

open.

certain

removable

if removed,

and

will thereby

;

IN-

WH

GH;

DO

HIGH

EQUIP

PO4t

EIL7

AND

danger-

op-

covered

meas-

within

of

allow

access to circuits

to human life.

AWAY

KEEP

Under no

within

a cabinet

supply line

or handle any portion

is

external

-q

nets;

even for

portion

supplied

to the

or to

testing purposes

of the

-

- -'

`

ble in testing

ance checks

at various

the

to

DON'T

transmitter

SERVICE

Under no

within
justing

sistance

DON'T TAMPER

Door

cabinet

a

the

of another

or safety

removed

placed

voltages

upon

from

FROM LIVE

circumstances

with interlocked

switches

with

power;

cabinets

apply

cabinet
circuits,

rather

points when

OR

circumstances

for the

equipment

WITH

interlock

or

short

circuited,

the

interlock

the

equipment.

carrying

CIRCUITS

voltages dangerous

should any person

gates

while power

to

the equipment

of

exposed equipment which

or to connect any apparatus

to

circuits within the

high

voltages

while

is

removed. Whenever

to

the equipment

any non -interlocked

make continuity

than

directly checking

any

high voltage is

circuits.

ADJUST

ALONE

should any person

purpose of

without

person

INTERLOCKS

capable of

switches

servicing

the

presence

rendering aid.

should

nor should

switches for

reach

are closed;

cabi-

feasi-

and resist-

voltage
applied

reach

or ad-

as-

or

be

not

reliance

be

removing

ADD

EN DA

The following

to

correct

this

instruction

tion that

1. The

transmitter

audio

60_0

of

fa several instances

book.

pedance should

2. Page 2-4. - The output

shown

to figure

nect

The

'T. section

the

3.

MOTORS.

application

plied

25.', may

primary volt age

ondary voltage, the voltage

the

motors,

4.

has been omitted.

audio

equipment having

ohms

A.U.....mtareac.es..1415cal_aten.as_unl

in figure

9-5,

ions

as included

lead from

center of the

Page

The statement -

by a 115 volt transformer,

Throughout

references

the push type

and plate

has

becomecli fficult

type

push-to-stop

transmitters

2-5,

ment
be

noted,

filament

switches.

of switch,

Figure

indicate only

circuit as

referring

voltage is applied to

notes

have

discrepancies

book

been compiled

that

and

to

input circuir of

is intended

rathe_r_t_hari.aanohms

to

output

in this

be 600

page 9-719-8 for the con-

the

should

ohms.

2-4,

is in error. Refer

in your

loading inductor to

shownconnected

be

loading inductor.

Paragraph b. -

2-1.

to the tuning

be somewhat misleading.

i s 115 volts but the sec-

is actually

this bockyou

illustrations showing

and

to

start

of

type,

now

2-6 and paragraph b.,

This

to

the pull-to-start and

is

being

one oscillator

being energized.

to figure

The power for

motors is sup-

24 volts.

and stop filament

type of switch

procure

being

built.

appear

add informa-

in

the 300G

be used with

impedances

as stated

instruction

ut

circuit,

transmitter.

as

the

to

TUNING

Item

The

applied to

find

will

new

anda

used

in 300G

page

fila-

It will

9-5, that

bothoscil-

-

later tubes

is operated.

6..rigure

that_

11.5

latör.crystal

an error.

to

the

7. Figure

of the

ity

in this illustration

value of these

5600 ;milt instead of

on the schematic.

7 .

- Et. _Not

pagi3--;-8 are the six 866-866A

tube. The correct

these tubes is 2.5 volts.

9.

ADJUSTMENT.

normal

lator

pending

25 ma that

20 to

justment

rience
of starting the oscillator

the

coupling

put circuit

stage

Item

started by varying

ommended

10.. It might be well

the

modulator current

tal

modulator

SELECTOR

AMPLIFI

ING

position.

whenever

vol

t5 'oppflexe

The

crystal

2-12, page-2-9.

feedbackcapacitors,

included

pane, rin-cf)..cateS

heater

Voltage

heater is

capacitors

the

. .

in thelist

filament

Page

olleratinT-Current

varies

upon

procedure.'

has

by

varying

59.

that

Step 4 under

It has

betwcen

freguency

is stated

prover

that

between the

andthe

the

If the

a new

been

grid

coupl

oscrliator

the

crystal

current

switch

ER PLATE

is in the807

cr

MODULATOR

the filament

.circ4itr.'11-hiS,

that

12 volts.

is

an

2000 mmf shown

found

-of the

and

.10

. instead or

under this

In additIon,

a pref erablemethód

oscillator

of

the

ing

cntipl

',rig

to

point out

meter

when

indicatesto-

the

relay

tle ost

iS

arplied

is

The'capac-

ltems45,

error.

Es actually

of tubes

voltage for

OSCILLATOR

27

is

capacitor,

be

TUNE-METER

PLATE,

PLATES

The

rectifier

on

that the _

oscil-

ma,

de-

trie
ad-

expe-

to

change

out-

following

cannot

it

be

is

rec-

procured.

that

FINAL.

LOAD-

-

,

-;

, .

:

t

-,,t.4.,-

-'*--

(OOG) (3-28-47)

.,..t'....-_.--"--..e-4.

,

r.,:'S;.......'

Cfri.j..-`4'....;:.*

'-

.e. .t.

' ::*ei. '''.,.

. "::,: f.;'=_,:.."-.-

-...:::,;:,,', ...J.

,t. :-_-_-,

-,..4-'*'Tr-7.?

,,,-...t-------.:1Agt.,...z_*.....-

.:;,-,:0,4

.... ?",,

,

-...,',....40

i:. "';',.-4...k..,;11-2-1-40.,`-

. "..:..- :,-4743r-:,;+0,......,14,.

_ .

-,-r.,4::-.'f:`,1;:Z.-,s=i4.=,,C,.- ,,_ _

'n

..,

.- :

-441V..1'4,..4"r-

,":-..4?.!fX..11(1.3.?..,:,.

V.!'

1-

S....-4":

--..7,

.;-;,,, viu":-;,:

-

www.americanradiohistory.com

TABLE OF

CONTENTS

Paragraph

SECTION

1.

General

a. Purpose

b. Mechanical

c.

Electrical

2.

Reference Data

a. Frequency

b.

Character

c. Power

cl.

Power

3.

Vacuum Tube Complement

1. Mechanical

a.

General

b. Tuning

2.

Electrical

a. AC

b. Filament

c.

Low

d. High

e.

RF

f. Audio
g. Metering

of Equipment

Description

Description

Range

of Emission

Output

Source

and Input

SECTION

Theory

Motors

Theory

Primary

Circuits

Circuits

Voltage

Voltage

Supply
Supply

Circuits 2 -7

Circuits

Circuits

1. GENERAL

Requirements

2. THEORY

DESCRIPTION

OF OPERATION

s

Page

14

14

1-1
1-1

1-2
1-2
1-2
1-2
1-2
1-2

24

2 -1
2 -1

2 -1

2 -1
2 -5
2 -6

2 -6
2 -8

2 -9

SECTION

1.

Installation

a. Preliminary

b. Installation

2.

Initial Adjustments

a. General

b. Function

c. Outline of

d. Energizing

e. Power

f. Filament

g. Tuning

1.

General

2. Initial

Circuit

Operation

a. Starting

b. Stopping

3.

Routine

a.

b.

1.

General

2. Routine

3. Voltage

4.

Fuse

Operation

Starting

Stopping

Checks

and

Replacement

3.

INSTALLATION

Procedure

of Controls

Adjustments

the

Equipment

Check 3 -7

Circuit Adjustment

Adjustments

SECTION

Equipment

Equipment

Equipment

Equipment

SECTION

Current

5.

Checks 5 -1

AND INITIAL

4.

OPERATION

OPERATORS

ADJUSTMENTS

MAINTENANCE

3 -1

3 -1

3 -1
3 -5

3 -5
3 -5

3 -6

3 -6

- 3

3 -8

4 -0

4 -0

4 -0
4 -2
4 -2

4 -2

4 -2

5 -1

5 -1

5 -1

-8

www.americanradiohistory.com

i

Paragraph

5.

Circuit

6.

Tube Replacement

7. Room

Breakers

Temperature

Page

5-1

5-3

1. Cleaning

a.

Transmitter

-

b. Air Filter

2, Lubrication

a. Ventilating
b. Tuning

3. Routine

a. Tube

b. Mechanical

1. General

2. Trouble

a.

b.

C. Power

Checks

Check

Shooting

Tube Failure

Isolating

d. Distortion

e. Parasitic

f.

Power

- g.

Failure

h.. Ventilating

i. Tuning Motors

3. Servicing

Code

Color

SECTION

6. PREVENTATIVE

General

Blower

Motors

and

Inspection

SECTION

the

Trouble

Supply

Troubles

Oscillations

Amplifier

of

Stage

Oscillator

Blower

the Equipment

SECTION

8. TABLE OF REPLACEABLE

Assemblies

7.

CORRECTIVE

not

Neutralized

Unit

MAINTENANCE

6-0

6-0

6-0
6-0
6-0
6-0
6-0
6-0
6-0

MAINTENANCE

7-1
7-1

7-1

7-1
7-1

7-2
7-2

7-2

7-2

7-2
7-2
7-3

PARTS

8-10

SECTION

9.

MISCELLANEOUS

PHOTOGRAPHS

AND

DRAWINGS

www.americanradiohistory.com

GUARANTEE

This equipment is guaranteed against defects in

material, workmanship or manufacture,

for a pe-

riod of one year from the date of delivery. Our
obligation under this guarantee is limited to

.ing or replacing any item which shall prove, by our

repair-

examination, to be thus defective, provided the item

is returned to the factory .for inspection with all

transportation charges paid., _Before returning any

item believed to be of defective material, workman-

ship or manufacture, a

mitted to the company giving exact information

to the nature of the defect. The information

include,

material

of parts. Upon receipt

pany, a returned equipment tag

to the shipper without

EQUIPMENT

SHIPMENTS

TION WILL

in as much detail as possible, all subject

listed under instructions for replacement

TAG MUST ACCOMPANY ALL

OF DEFECTIVE

BE TAKEN ON

RETURNED TO THE COMPANY UNLESS
SHIPMENT INCLUDES THE

detailed report must be sub-

of the report by the com-

will be forwarded

delay. THE RETURNED

PARTS.

NO AC-

ANY EQUIPMENT

RETURN TAG.

COLLINS

RADIO COMPANY

as

shall

THE

iv

,-.....,

www.americanradiohistory.com

LIST

OF

ILLUSTRATIONS

. Figure

1 -1 300G Radio
1 -2 40F
1 -3
2 -1 Tuning

2 -2

2 -3 300G

2 -4 Motor

2 -5

2 -6 Filament
2 -7 Low

2 -8

2 -9
2 -10 40F
2 -11
2 -12 Audio Driver

2 -13 Metering
3 -1
3 -2 300G

3 -3

3 -4 Power Level

3 -5 Test Meter

3 -6

3 -7 Tuning Control

3 -8

3 -9

3 -10

3 -11 300G Transmitter

3 -12 RF Tuning
4 -1

5 -1

7 -1 Door

7 -2

8 -1

8 -2 Audio Frequency

9 -1

9 -2 300G

9 -3

9 -4 65Q -30
9 -5
9 -6 38N

9 -7 300G
9 -8 300G Simplified

Frequency

Functional

300G Transmitter

Transmitter

Driven

Power

Voltage

High

Voltage

Oscillator Circuit

Frequency

297 Crystal

Floor

Plan

Transmitter

300G Transmitter

Tune Meter

Block

Block

Diagram

Diagram

Block Diagram

300G Transmitter

300G

Transmitter

Panel- Inside

300G Transmitter

Audio Frequency

100

Watt

250 Watt

300G Transmitter

Transmitter

Transformer

1100N

Vertical

-1

Control

Complete

Title

Broadcast

Block

Motor

Control

Circuits

Rectifier

Rectifier

Oven (503

Circuits

for

Switch (503

Switch

Selector

Curves (503

Operation

Operation

Winding Data

Cable

Schematic

Assembly

Circuits

and Modulator

Chassis Cabling

and

Transmitter

Control

Unit (6978)

Diagram

-Rear

Open View (9758)

-Front

(503

Circuits

(503

(503

2268

Circuit (503

Circuit

Schematic

Control

Unit -open

2267

(503 2272

Installation

-Top Rear

Bottom

-

2258

(503

Switch

Switch (503

Adjustments

of

Power

of

Panel

of

Control

-Front

2266 002)

-Front

-Front

(Inst

(503

Open View

2270

(503 2263

002)

(508 0899

Rear View

2262 001)

(503 2261

Circuit Checks

Open

View Closed

View

(510

0320

00)

800X)

2269

002)
(9757)

003)

2259

001)

002)

2265

001)

(503

2264 001)

001)

View (6779)

- 2 -8

Schematic (503

003)

20)

2271 003)

View (9761)

(9762)

001)

001)

2260

001)

Functions

View (9757)

Open

(510 0320

(6973)

00)

View (9764) 7-4

-Rear

Response
Response

- Bottom

-Top

Schematic

Schematic

Meter

View

Open

and

Distortion

and

Distortion

Front

Front

View (9763)

(503 2273 004)

(508

0597

Schematic

Door

Schematic (508

(508 0145 40)

(508 0206

(9758)

View

10)

30)

Curves for

Curves

(9760)

(508

0194 30)

for

0143 50)

Page

1 -0
1 -1

1 -1
2 -1

2 -2

2 -3

2 -4
2 -4

2 -5

2 -5
2 -6

2 -6

2 -7

2 -9

2 -9

3 -1

3 -2

.3

-4

3 -5

3 -5

3 -5
3 -6

3 -6
3 -7
3 -9

3 -10

3 -12

4 -1

5 -2

7 -5

8 -11

.

8 -12
9 -1

9 -2
9 -4

9 -3

9 -5

9-7/9-8

9 -9

9 -11 '9 -12

9-13.'9-14

www.americanradiohistory.com

iii

REPLACEMENT OF PARTS

In case

sired,

pany.

failure and must

(A) Date of delivery of equipment.

(B) Date placed

(C) Number of hours in service.

(D) Part number of item. .

(E) Item number (obtain

(F) Type

.

(G) Serial number of unit.
(H) Serial

a replacement under

a full report must

This report shall cover

include the following

in service.

matic Diagram). _

number of uriit from

moved.

number of the complete

(I) Nature of failure.

(J) Cause of failure.

(K) Remarks.

the guarantee is de-

be submitted

from Parts List or Sche-

to the com-

all details of the

information:

which part is re-

.......______

equipment.

_

_

.......

When requisitioning

lowing information must be furnished:

(A) Quantity required.

(B) Part number of item. ..

(C) Item number (obtain from Parts List or

Schematic

(D) Type number of unit.
(E) Serial

(F) Serial number of equipment.

NOTE: Blank Service Report forms will be

found in the appendix of

number of unit.

replacement parts, the fol-

.

Diagram).

this instruction book.

- -

..._

-

.

At;

;Jr

44".. ,4-

20C.G

Radio

6.-oadcast

www.americanradiohistory.com

GENERAL

DESCRIPTION

Section

1

GENERAL.

1.

The

purpose

a guide

and

Broadcast

a.

300G Transmitter

for

ter is

system.

feedback-errs-flit

high

to

maintenance

PURPOSE

high

fidelity

high

fidelity.

of

the

Transmitter.

level

modulated

The audio

these

instructions

installation,

of the

OF

has

broadcast

is cgirgirja

Collins

EQUIPMENT.

been

with

requency

adjustment,

type

designed

service.

a Class

system,

to

give

----------SECTION

GENERAL

is

to

serve

operation

300G

Radio

-

The

Collins

particularly

This transmit-

B

modulator/

employing

exceptionally

203

1st
65

1

DESCRIPTION

"b: MECHANICAL'

as

mitter

appearance.

space

approximately

is

293/4"

transmitter

the

,the

front.

3ows

iñ

nance

vided

*feature

working

_._provided

_fife

type

..

pie

"iTe front_p

ewer

may

ti

the

The

of

with

be

á ng

e

air

purposes,

on

frequency

osc'llator.-

hTov

upright

Ter-

earnporiñf.'s

g astiis ters-ócated°in

awing

T oCi ñ

tuned

a

"Three

tors

s

circus.£_,

capacitor

housed

the

both

provides

part

with

protection

constructisx}

removed

is

chassis

separate

a

sÌug

Thethrd

Ti;-:

in

The

deep

by

1,370

is

such

Full

vision

tubes

is provided

áccés`s:

full

the

front

quick

of

the

high

control

each

equipment.

nel

óf the

fò_r_repair,

--

is located

e d t

and

The

circuits

flexible

inthe

motor

the

intermedIate

-

DESCRIPTION.

a single

complete

41"

lb.

that

door.

length

wide

The

all

tubes

of

the

For

and

rear

and

convenient

cabinet

equipment

by 78"

by

hinged

transmitter.

voltage

of

maintenance

unit5is

,Two

complete

33Q

uni

he

óscillatór3not

or

in the

roug

circulated

are

urn-

steel

network

air

is'drawn

the

rear

motor

mo or,

ribbon

drives

uclsh

coil

amp/

-The

of neatly

high

arrangement

are

accessible

power

service

interlocking

A

ádjústm_éñt

to

doors

driven

the

means

doors

of

the

The

pers

of

switch

a ows

rear

of the

thé

cool

-in

of the

wo

that

variestFF

óf -their

rotor

fier

amplifier°ánd

of -ggTass

and

cabinet.

access

timt.-

the

units

se7ëctioñ

in

front

the transmit

through

each

of these

of

stägëy

trans-

styled

occupies

and

weighs

of

the

from

win

maiote-

are pro-

This

to the

door_s_are

switches

"plug

-in'

are _s_up-

located

on

of

operation

A vën=

cabinet.

of

the

spun

cabinet.

circuit

mo-

pp-

respective

a tuning

a

-

*

-

Figure

CRYSTAL

OSCILLATOR

5tr

r ,,~

f

`? /gyd

¡ t

!

PREAMPLIFIER

-

1 -2.

-3

,

!

40F

- ._

-

Frequency

,7

3

Control

s

Figure

c.

ELECTRICAL

Unit

-

.

1 -3.

Functional

www.americanradiohistory.com

(1)

Block

Diagram

VOLTAGE

DESCRIPTION.

SUPPLY.

-Two

rectifier

TO

ANTENNA

TUNING

sys-

UNIT

1 -1

Section

terns

necessary

the plates

One

Ìow

for

thé modiiTtörs."

_loys

amplification

pull

pair

-

lator

ating

four

diate

is

age

'AT"

lator

Type

fier.

8Ó7

cut ,

is

also

er

tubes?'

810

tubes

work

tank

tuning

pic

-f -ná7 to

m- o

bring

ter. -No

dar`r-accessory.

`téi déd

to W1i

' transmissiói

----

operation

REFERENCE

2.

a.

FREQUENCY

designed

wi

operat

to-I600

once

may

1

are

employed

direct

and

'stem

employing

voltage

(2)

àm

ofWAo

circuit')

CiasT 73.

(3) RF CIRCUITS.

four

AUDIO

7

to

rectifier

ër circuit.

r -f stages-

ampl

with

6L6 is

cam pentode

er

is

contro-lle-d

cut

quartz

a high

empToÿëd

T

íl-e iñtermëd'iate

in this

current

scieens_

the auTc

utilizes

tu :e_s_operating

itilizes

io

"`Thy

tubes.b

SYSTEM.

a pair

a pair

an

oscìllatoi?

d a power

byyemperature

plate

degree

as

_tubes

e intermediate

used

as

t íF e gril

Th

yower

in

a parallel connected

ö_ u tput

and "T"

and

loading

the

up coil is

ground

mont orf-

-for

use

1ch

it is coñnebtéd"bÿ

rtiñe-

w7.-fhán.

Collins',

for

ó

kc.

been

sset_,

require

network

section

networks

tank circuit

connected

to

provide

equipment to

iñg_equipment

The

with

adernar

an

The`trañsmitter

e teii

Type

6M

DATA.

RANGE.

use

in t

íf e- broadcast

n

any

one

A fter

the frequency

any

substantial

modlficátion_of

transmitter

voltage

of the

for

transmitting

twö` rectifier

and exciter

hig

vo

----A

ogle

of bJS`

fine

áuaiö-

driverrem

C`lass_A..

ó pe

-

he

equipment

a buffer,

ampli

crystal,

of frequency

a

ampl

in

ampií$ér`tplate

rcuit_of

filter.

and

the

a1_program

or

frequency

prove

bufferár

fier`(utilizes

a parallel

the_

circuit,

ís

a combination

The

yärT

áre_ind

the

o_ther

from

the

á means

output

is

300G

transmitter

antenna

m-e-án

_._òf

26W.

-This

in

of

change

the

output

GENERAL

to

supply

application

tubes.

tubessuppli-es

stages

age

tubes

810

3

and_bias

supply

stage of

in

a_push-

Th

lages

----

employs

an

interro

lo

m_ odu-

-_

Thé oscillatori

coefficient

ing

an

stability.

isolation

connecte

power

ampli-

two

Typé

tank

irciij-

ámpli-

tvwa_Type_

The

pi

bles

in

cioxs,._on

forloading-

antenna

offccoupflj

of

the_transmit-

provided

is

amplifier

transmitter

band

the range

o eration

in frequency

termi-

g_the

is

tuning

á bncentric

esigned

only

tank

the

to_

-'

em

audia

s a

oper

e,

oscil-

A

irl

plate

-net

-

the

or_

as a

in-

unit

for

such

is

and

540 .

DESCRIPTION

cuit capacities

`system.

The

oscillator

compensate

same

as

the

b.

CHARACTER

tion

system

prove

e

u

:läting-frëgúéñcies

carrierr-fi

Zit-the

_é. POWER_

liver

nrequency

a

resistive

ance

for

üency

assigned

250

watts

within

va

ue

in-stanta_

transmissióñ

_by reducing

fier

tubes.

f

d.

POWER

MENTS.

erate from

neutral

at

400

at
approximately

dbm

The

1

-This

a 115 volt

power

100%

modulation

cps

is approximately

average

An

* is

audio

milliwatt

program

audio

required

input impedance

reference

° m/ t.la ii Ga

3. VACUUM

The

vacuum

ment

are listed

Quantity

2

1

2

2
2

2

4

2
2

Tube

6F6
6L6

807

6J5

-6A5G

866/866A
866/866A

810
810

as well

unt is

unit.

The

output

o the

l00`,;ó

of70 to

eu_s

the

TUBE

300G transmitter

modulation-òf

between_30

deviation

value.

OUTPUT.-

of radio

the

reduction

plate

SOURCE

equipment

system.

level,

1.5 kw

input

for

level

c

COMPLEMENT.

tubes

below:

Type

as changes

a crystal

crystal

frequenc

OF E_

frequency

desired.

MISSION.

the carrier

'an-a-10,000

is

held

Theránsmitter

frequency_

range

200

The maximum

with

level

employed

of

540 to

Ine

load

ohms.__Prwision..is

of_power

voltage

I. phase

at a power

full

-600 ohm

on

_

...""

AND

a

1.7

INPUT

has

been

60

modulating

kw.

the

power

of

approximately

100%

is

&BfJ

Goo

in

Function

R -F oscillator

Buffer
Int.

amplifier

Audio
Audio

L.V.

H.V. rectifier

Modulator
Power

amplifier

driver

rectifier

amplifier

in

the

neutralizing

controlled

,

-The

is 'designed

to

within 10

ower,

1600

having_án

to

the power

REQUIRE-

designed

cps

or

power

frequency

When

tone

ohms.

rase.

modulated

requirement

factor

the

of

modulation.

300G

-

heat

being

the

modula -

at modu-

cps.

The

cps

will de_

on any

into

kc,

impe-

made

100

watts

ampli-

op-

to

208;230

demand

of

is

85%.

+19

--teR

5

equip-

Unit

40F

33Q

33Q

33Q.0"-

i

33Q

401W/"S

401W I°

3Z ""a

tb'

v

1 -2

C.

www.americanradiohistory.com

THEORY

OF OPERATION

SECTION 2 .

Section

2

MECHANICAL

1.

a.

GENERAL

in

housed

a

wilted-

Components

ing holes

the

hold

to

removed

300G

rout of

power

switch,

confrTw

justments

motor driven

by

ing

are utilized. The

or replaced. All operating

Transmitter are - Tocated çönvenlently.-Qn,tlie

the

cofifrol, a plate power

a

meter selector

in the transmitter.

the selective tuning selector switch

control

THEORY.

-The

single

300G

cabinet ---M -c st

olï`rticál' chassis inside

mounted

that are

securing

ábinet_

re serves` too contról`a e uning

variable

knob. Both

following

this chassis have

on

tapped in the

bolts in place while the

They consist of

switch,

tuning

sides

the vertical chassis:

A

Unit

11M

Output Network

Unit B 3Z Final

C

Unit

Unit

Unit

33Q R -F &

D

401W

E is mounted

/A;

Rectifier

the cabinet

on

THEORY

Radio

Transmitter

th

of

components

the cabinet.

vertical

controls

a filament

control

a power

and a single

Full

control ö

elements

is

and the tun-

of

the vertical

units

are

mounted

& Modulator

Audio Driverj-H

Relay

&

base.

OF OPERATION

is

mount-

chassis

nut is

the

in

level

tunnn

ad-

a the

provided

chassis

on

a°b i

g

Unit

. _---"- ° -./

The

two frequency

plug

! the

the 33Q
units

-in

type.

front

panel for these control

aiejdeptical

damaging the equipment

wrong

used to tune the
cuits are (refer

power

Iñg

mg motors

Item 25.

. trolled by

the

2.

2 -5.)

the 11:b-_-

receptacle.

b. TUNING

MOTORS.

300G. The three tor

to figura

amplifier p ate

netvoc.

The power

is

supplied by a

Operation of the tuning motors

the tuning control switch,

tuning

ELECTRICAL

a.

AC PRIMARY CIRCUITS. (Refer

-All

selector switch, Item

THEORY.

power

ol

contactors

c

£ÿpe..

trolled by opening_or

marÿcircuìts. T

stant voltage transformer to supply

control units (40F)

Two

receptacles

so

that there is no

by plugging a

-Three

2 -4

tunin

for

äpplication

115

in the

A11 power

closirig

.e300G

transmitter

t Or plate

nd

the

cvc

are

provided on

units. The

possibility

unit into

tuning

motors are

driven rir-'

thë_äntéïlriä

tö thé tun -

volt

transformer.

Item

116.

equipment

circuits

transformer

uses ä con-

power

of

are

of

the

circuit.fJ

Ioád-

is con-

and

17,

to figure

are of

are còri

pri-

-toot

the

Figure

2 -1. Tuning

COLLINS

A

B

C

D

E

F

G

a

I

J

K

L

M

.N

o

P

@

R

S

T

U

V

G1 311 7010

X 311 6000

Y 311 5010

z 311 7000

Motor Assembly

990
230 7000 00
369 1001
369

369 3000

340 7040 00

507 3878 00
502 0468 001

507

507 3868
507 3867

507 3866

507 3865

507
507 3863
502

507

500

500 6537

507 0054

500
502

PART NO.

2120 00

00

2000 00

00

3869 GO

00

00
00

00

00

3864

00

001

0466

2828 50 . .

OOA

2684

OOA Collar

00
5952 OOA
0370 001

00

00

00

00

- -

.

ITEM

98P 48T

24 y Tuning

Plug
Retainer
Receptacle
Ring Spring
Spur Gear
Bushing

Bracket

Bearing

Pin

Clutch

Drum

Clutch

' Clutch

,:

Ring

Pinion

Pinion

Collar

Bearing

Oilite

Bushing
Nut

Standoff

1/4" Shaft

7/0 Taper Pin

6/0 Taper Pin
5/0 Taper Pin

Taper

7/0

1"

P.D. Spur

Motor

Plate

Plate

Pin 3/8"

Gear

1/2"
1/2"

2 -1

www.americanradiohistory.com

Section 2

THEORY

OF OPERATION

AIR

OUTLET

AIR

VENTS

VENTILATING

BLOWERS

AIR FILTER

Figure

2 -2. 300G

Transmitter

--Rear

Open

View

AIR

AIR

AIR

VENTS

BAFFLE

FILTER

2 -2

www.americanradiohistory.com

THEORY

OF

OPERATION

Section

2

Figure

2-3.

300G

Transmitter

www.americanradiohistory.com

Front

Open

View

2-3

Section

2

O

O

o

O

o .

o

o

O

O

o

o

THEORY OF

o

O

MOD.

Figure 2 -4.

OPERATION

807 PLATE

OFINAL

AMP.

PLATE

MOD. PLATES

O

MOD. PLATE

PLATE,

2.

O

Motor Driven-Circuits

LOADING

L

IIO V.

MOD.

MON.

filament

may

'chan

béen prove

the

l tÏem

re

powr

tub-5-11.77-the

open

t

7,

- -- - -. -..

tac

the

lié

5,

re

plate

çlosmg

reláÿ

-_ ó

The

£hë circuit

töñ.Ttem

'l'heilámént

open

Item 1,

Ìterñ"20

blouser

g1. :n

power to the

the

2 -4

transformermáries.

vary

as

e in the filament

ed

1tübes ágáirist

'iseñër

aT -Item

-ting- IT.15 "rat

Three

con ro

-

major

also acts

powerr

ver-start~bütto

circuit

contacts

a

fransmitter.

1, and prevents

unt'iI

súfficient

transmitter

magnetic circuit

t

íh major power`

circuit

e

reaker serves

circus

filament

as

mugt-'bè

cá be

-th

-6 filàmeñt

cane

énérgized

for

br- e

f3,

and

irelayis

energizes

-t

íe time

-aker,

1 -l: `Thé'óperatiari-

filament

much

as

vo á

with á time_

-damage.

izéd

üpóii

£-ime

-üre.

aì"ï3ir" ró de

power

a

supply

disconnect

cf

applied-to

circuit

on the

the

operation

i

m 5, tF

the

firameñt

held

the

constant

cTelÿ

relay,

`'`,ment

voltage

transformer-S--o7

After

approximately

.

15%

without

e. e7tran

delay

The

allé

ópérâìi

the

application

has

elapsed-to

to

warm

breakers,

Tcizcüits

two

purposes.

protection

circuit

scarf h

before

éit í1

t&ie

transmitter

breaker

by

pressing

transmitter

of this

ë fiIa

stop-button,

opéiated

voltage

Item

tranSIOrmeT

The

line

voltage

noticeable

a

mitterhas

relay

to_protect

time

delay_

relay,

oL

lament

of_platel

allow ai

up

to the

Items

oTthe-trahsmìtter,7

breaker,

-This

erñlament

control

relay

ments_tartb_ut-

by

bf-firäment

4,

the

T.

á1f

proper

5, 6 and

to

isolate

in

case

of

Item

circuit

or

.

After

hëFfiIan

the_fxlament

its normally__

trañsfr'mér,

vèñtilátirig

,-

30 seconds

panel.

isis

thröügfiJ

Item

relay,

r-rä_-

súpplies

ilb-es in

ent

13,

60

220V

t

a-I

!..v.7

C,ß

24

C.P.S.v+

. --

I-3

>r't

26

lo

5

2 0

-

" - d:

)

R

.

7-ti

1-2

_

r,

t

22

Figure

2.5.

Power

Control

Circuits

www.americanradiohistory.com

THEORY OF OPERATION

Section

2

relay will close the

delay

time

the

Toz the operation

when energ>zëi

voltage cïrcúî

low

However,

ofthë Iów voltage plate

wiTI còìñpiete

before the low voltage

energize i will be

`VOLTAGSÜUPPLY

ore

high

voltage

can be applied to

'grid power amplifier

8F6

OSCILLATOR

'OF

MODULATOR MODULATOR

20

BARG

AUDIO

86e-

866

23

Figure 2 -6. Filament Circuits

contacts

-the

circuit

réäkëi-

Itém...r V '

supply will be

necessary t-o-ç1ose the

circuit breaker, Item

the modulatory

uses it will

810

BL6

SUFFFFER

BIO

necessary

Te-

807

AMP.

{NT.

33Q

810

POWER

z

AMP.

BARG

AUDIO

/\

AMP. AUDIO

6R OJO

DRIVER AUDIO

n

áß

atm.,

866-866A 866-866A

^

Yai w

-868A

866-666A

yot

required'

relay

`Which

up

to -tEe

7.

INT.

AMP. POWER

866-866A

/

LOW

Be-

to

807

.AAMP.

810

AMP.

IIc

DRIVER

HIGH VOLTAGE

close

breaker,

closed,
ing the

The relay,

FILAMENT
PLATE

t

interlock

- tacts

ation

transformer,

lamp,

..-> b. FILAMENT

-Filament power

is supTierI'ÿ

cáted

by power

- *Inch

R

c

. ployed to provide the best possible

r e -Iätion. However,

providë3

cilitate

the

item

6: When t e circuit

the relay, Item 2,

PLATE POWER

Item 2, will

POWER

POWER

STOP button,

switches, Item 19,

2 -2 and the circuit.

of the relay,

Item 22, and the

Item 153.

CIRCUITS.

for

stepdown

in

the same

A i ament

apliE

.

from

hi

is energized-When-tire

ose e constant

with

raising

the

taps

or

unit

lowering

be held

STOP button,

Item 2,

all tubes in

as the tubes

constant

vóltág`e`rráñsf-

alf- filàmëñt

on the primary

Transformer, Item furnishes

the 6F$ oscillät

ro-i7-the

intermediate

8807

et

33

Item_ 42, fúrñishes voltage

tithe

amplifier.

mplifier tubes andië twö'6J5

Separate

filament transformer

a irectifier system, the modulator

fier túbes,_ Transformer, Item

for application to the filaments

rectifiers

w

la

furnishes voi á

low voltage rectifiers

-fhb

formers

or the

Items

fi ament o t e two

the

(four 866

Items

two

28

an 29,1úrnis voltage

/866A).µTräñsförmèr,

e for

application

3Ó .a-3Ì

mo irarers

power

UPPLY

S

breaker

may be

START button,

operated

operated through

Item

the normally

breaker,

Item 5.

will

energize the plate

PLATE

(Refer

trans

o

transformers

voltage

contácts

filamentvoltage

transformers

the

secondary

fil

6L6

buff_

tübeS.

the

to

(two

ürñish

two

au io river tübe_s.

are

provided

and

the power

21,

furnishes

the

of

to the

86Z$56`A

filament

g=7"-

for

amp

ih

er

_circuit

been

has

by press-

'Item 18.

Item'- 23, -the..

18, the door

open con-

The oper-

POWER pilot

to

figure 2 -6.)

the

transmitter

that are lo-

that

are

being

are erieigized

tràïzsförm

öiIïëm

ormër-.-1-i-...&.-

windings

1 We

to fa-

voltage.

voltage

t

the ttó

and

T`rä_nsfö_rmerr

6Á5G

audio3.3

for _each

ampli-32

voltage

voltage

high

-item

filme

.tsof

d Trans-

voltage

fis

Amers,

application to

tubes

(810

the

er

m-

are

23,

s)

?3

' .

32

Q

Ct

115

TO

L.V.

CIRCUIT

BREAKER

24

Figure 2 -7.

37

868A

888-

Voltage Supply

Low

46=

37

48;

82

420 V.

130

130

h

O

u

d

o

2

O

2-5

Section

2

THEORY

OF

OPERATION

TO

H.V.

CIRCUIT

BREAKER

c.

IOW

2,-7.)-2-Two

rectifier

system.

rectifiers

Ttém

Trêär

he

out

tion

choke

_ground

reduced

plication

866

- 866A

.'22

VOIÇE

Type

tubes

are

-

te

vge

by

the

he

after

approximately

ut

oft

potential.

through

o ih-

Frafës

81

SUPPLY.

B6.6/866A

có

necfczin

öIta

is

operation,_

c!osingof

e

rectifiers

fie_

The

voltage

a vol

age

and

81

401

half

applied

of,

the

the

30

seconds

is

filtered

negative

divíC

screens

_-- Figure

(Refer

wave

a fúÌ1

to

the

time delay.,,relay,

low

from

ìñg:

of

to

mercury

wáve_rectifier

löw

voltage

have

elapsed.

by

a two

.side

is

this

supply

tem

the

oscilla

866-856A

2 -8.

figure

vapor

_Xöltage

circuit

sec-

above

is

or

_áp_

pr

High

115

g

Voltage

4

G7

buffer

of fi

output

me

ing-

low

supply

ì

eostats,

d.

HIGH

2 -8.)

-The

wave

rectifiers

ye

866

-866A

1010

21

Supply

1-

audio

amplier

voltageis

amplifier

v-oltáge

furnishes

ëm7

VOLTAGE

high

is

in

applied to

to...the

bias

voltage

a full

the

36

and

audio

appl'ied

tubes

stages.

for

the

a

SUPPLY:

supply

wave

high

36

..

.

_"

45

driver

to

ffie

In

addition

_mention

modulagor

means

z

o'

(cf

(Refer

_employs

rectifier

voltage

system:

rectifiers

45

-`°.-.

tubes.

plate

to

bove

Jibes.

varying

to

four

1550

V.

80

The

of te

s pply-

this

The.: The

h s

figure

half

Plate

after

_:

w

of

Y

TO

RECTIFIER

2-6

151

Figure

2 -9,

6F6

Oscillator

OSC,

10M

Sihematic

_

2500

-

TO

L.V. RECT.

60

.001 MFO.

{TO

6L6

GRID

www.americanradiohistory.com

the

time

delay

relay

has

voltage

pcnver

2._

px-r-ampliei

sùly

start

ciercilifbreakei-a-n-d

161-iitIter-ri18.-Platé

and

hy-flipply:::Two-P-a-Eillel

eries

with

the

P-577eillitliffe-i--plate

-'776/ta7,4Trorri1550

-age

orthe

_operating

ing

at 100 watts

contact

"re-graör-sn

P5STIT6Tir-No

4-)p-ribli-tr)-the-modulairiiihèS-fo-r.-.loW

atiön.

power3amplifiers

at

250

watts,

output

of

the relay,Item

the

rerclUCtio4"-ii-fri-ade

'l'he

power

operated

modiili4oL

yil.ts

to

and

level.

8,

pouvez

level

tubes

connected

1150io-lfsTE-6-51-a-e

being

1150

The

"short

switch-is

ih

adjustment_may

-

units

MP-1

(Refer

are

furnished

to

.

CIRCUITS.

40F

oscillator

by

closing

pressing

Viilfa-e.

are

resistors

lead

1550

volts

volts

when

normally

out"

th-e-d-r-o-P-p-rn`g

in

ffieoItage

power,

figure

2-9.)---Two

with

.-.

THEORY

the

high

..

the

plate-

for

the

furnished

dro_pthe

volt-

when

operat-

closed

the

!Hi

that

operT_

be

made

-

the

300G

OF

OPERATION

ransmitter.

power

)

Type

6F6

in

is obtair

in

the

from

the

Unit.

Te-Tent

-

supplY.

67:127

"1E7::

-Conlirceirld

is

CUit,afldthepItesuplies

-the

électron

--tr-o-n-gr-eani-is

--die-fifSt-tiio-sgrid,

ilf-tilè-§à-trie-frequericy.

k...reen.--trrpraztically

Each

oscillator

supply.

power

Th-e-Fry-tas

arnTraerl7)eil.tT.e7Pil-a-Ment-p-Oi.ver

transformer,

3.32.

unit.-PIate

low

voltage

The

oscillat:érnp-loyed

frequency

voltage

I

or

d

and

stream

Tfa'rled-b-y-The

ana-gEFeëh-P-5\7-VeFfs-6-51--i.ined

stability

.

variation

2

of

the

6f6

anode

e

supplies

of

the

Hol,ving-f7the

producing

Théthit-d-g-rTd'

eliminate

Section

is

complete

I-osc-illato-r--employs

against

.

in

tube..characteristics._

except

Item

277-1-6Fared

in,the-4161W

variation

_

in

pentodeñstjtute

road.

plate.

current

capacity

osciflatàrcir-

Tiie---Plat-é-

TElsle-c---

potentiars-on

in

the

acts

between

the

oscillator

a

any

o

for

dc

.tfle

is

load

as

2

a

a

Figure

2-10.

40F

Frequency

www.americanradiohistory.com

Control

Unit

-Open

View

2-7

::,

t-.

.

zeètion

2

-THEORY

OF

OPERATION

the plate

She small

_across

_may

. the

found

ra

óf 200 tó 30

en

étt

--(-Refer'tb-

Tl3e__oscillators

temperature

_

aTs

-. degree_centiggrade.

Type

at aÓ

thermostat

_40F

this

not

couple

`6L6 bea

stage.

oscillätor

'variable

807 beam

cuït._

is_also

fier tubes.

and may

_transmitter.

able tap

and the

variable

the

crystal

be

varied

capacity

necessary,

the

in

in parallel

connecting plate

fc'gure

coëffcient"AT"

i

less than_t_hree

297 crystal

_degrees centigrade

having

IJñit-m_ay

way

effect

The

to

be selected

the remo

the

operation

output

the buff

pöiv'er amplifier

The coupling

and

the

capacitor, -Ite

Thy

te_-

mediate

pentode

The

iiïtermediate

used as

the.grid

The

controlled

be

'fhé

so

that the value

be varied.

power am p ifier

ode tubes

ut ö

cavilled to

pressors,l%ms

' " osclIla`tions

riTi a.tión;çïrcúltis

1ìï a par

einter tat

the grids_of_

118,

"in tl-ie pöwër

capacitance.

first two

capacitor,

so that

range

a

grids of_th_

rtem

the

frequency

±10

to

with

the

20 cps

crystal.

the frequency_may.be

cQps ley

are supplied

óveïtThe

a

o

r

grid

tubes in

tuning

ductor

The

Jggb

r '

compl

The

adjusting

and

the

with

_cút quartz.

parts

,in

a

Each crystal:

_is

crystals

by

means

0.2 degree

using

r

of

of the

sensitivity.

'the

öiis

ooscillätor

transmitter.

oscillator

isolation

o

is

"between

tfieeli

of

n-59.

ampler

amplifier

circuit

amplifier.

em_pl

-o ed

the

ffer

utilizes

a parallel

plate

for

the power"ampli_

capacitor

from the

of inductance

emplöy_s

nnected

..:_

amplifier

the 810

amplifier

a

combination

capacitance

front._pane_of_tIie

is provided

two
circuit.

s.

The_parasitic-sup-

élp

súppress_all

circuit.,

is

is

e

oscillator.

is

65,

connected

of

operation

by

varying

If

varied

over

the

air

gap

quartz

million

mounted

crÿsfal.

selected

plate

drift

crys-

in

aremaintained

of

a __mercury

Either

switch,

is

output

is

Item_

unit

capacityy

A

iñ

the`6úffer

b

f

varie-ci-by

_tw.o_

does_

Type

Type_

connected

tank_

circuit

motor

Type

is

driven

with

a

mov-

may

easily.

.810tri-

_gut -

he

capacitively__

.parasitic_

-.

The.neu-

of inductance

arable

Theme

it

be-

low

per

12,.

ely

the_

the

cii-

is

a

a

_

power

as ólñblñatïón

_

This

combination

-' va ue.

works-

are

employed;

the

other

fixed.

induçtó

coupling

the

of

terminal

An

antenna

the

antenna

tical chassis

Tránsmittér

f. AUDIO

, _The.

,

...

audio

circuit, is

ifv`

Ari

_DBM

..She

audio

is

designed

amplifier

.audio

of

resistance

a

Tëmlñals

The secondary

resistors

The

sij stage

pair

of 6J5 tubes

'The output

grids of

e mploys

Circuit.

rormer

Two

as modu

operating

lated

b

ack

network

coupled

amplifier

plate

pi- network

reduces

e

variables

areindugtors.

one

for loading.

The

arms

óf _th

s _A__pickup

the

monitoring

transmitter

to

ground.

ammeter

lead

and is

and

may be

when

the

CIRCUITS.

frequency

designed-to

audio input

is required

input

for

such astÌie

input

voltage

ánß& the

across

of thé

the_audio

a pair

The,

coupled

Type

a

ors, w1

wl

va

a

6ackto

for

impedance

operation

network

á_udio

of Item

eác

of audio

in á mush

6J5's

drive

of

6A5G

output

tó tt ejrl

810

tubes

fixed

'able_resistor,Item

from

the

tank

and

'andr"_T"

harmonics

in

the

tank

_ j

wo

tuning

All

values

coil

tó

Motor"

thé

_

section-

_provid_e

for

equipment

is

connected

This

inductor

:is

.connected

,mounted

read

from

"cabinet

door

(Refer

system,

give-

level

full

ColIiils'

is

_applied

employing

exceptionally

of

approximately.

100%

is-480

with

'áì1

Type

across

inserted

_input

32 is

transformer,

shunt

iñding.for

amplification_

-pull

is

,resistance

tubes.

tubes

in

s of

volts

á

the

on

w í ñ

the

of

audio

operating

00

bias e bias__

the

output

seconda

output

networl

sectiöli^

tò

-ä negligi

ii-d

loading

tuned"

tiik

circuit

of

capacitance

are-várial

a_

to

from

on the

ohms.

the outil

the

is

also

in

series

1100N

the

front

is

closed.

to figure

a feedbac

tone

modulation

The_syster

external

6M

or 26W.

the

between

ed

by

two

better

regulation.

amplifier

coupled

The

audio driver

CTäss

A amplifiër

driver

mòaüla

Class

B

t

eir plates

supply

130.

th

ome dulators is

a i n g

s of tj

fil

r

induct

a

means

anten:

variab

vii

ve

of

ti

¡-

2 -12.)-

high fide:

progran

Th<

terminale

the

inpu:

Item

32.

loading

utilizes

circuit

to the

is trans -

or.

are used

regu-

is

The fe_ed-

input

e

I

a

2 -8

0

O

0

Figure

2 -1

a

0
0

o

o

1.

297

A

B

C

D
E

F

G

H

J

K

L

Crystal

Oven

COLLINS

500

1357 00

501

1356

500

1358

190

9310

500

1672

500

1670

190

7233

500

1671 00

292

0013

PART

00

00

00

00

00

GO

00

NO.

ITEM

Nameplate

Air Gap
Locking

Tap Plate

A -T Cut

Isolantite
Thermometer

Anvil

Heater
Isolantite

Thermostat

Angle

Regulator
Ring

Crystal

Ring

Element

Base

Thermostat

'

Guide

Cover

32

83

3900n 250M

2000MMF

113

/OOMMF

AUDIO

6145

AMP

THEORY OF

DRIVER

6A5G

OPERATION

.POWER

BIO

.

AMP.

2000MMF,

+

LV. LV.

RECTIFIER

LV.

RECTIFIER

transformer

output

lating

100

-All

rectifiers

of the moduläto-

the

-7:

vliT iln

filament

and

the filament

6F6

05C.

49

41

4000n.

250n.

the

of

audio amplifier

r -f output

iê frequency

CIRCUITS.

voltages

audio

tubes

volts

meter

61_6

BUFFER

2000n

Am°

U010

130 ?

ti

250n

Figure

iicúit

of

the

range

except

can

and

the

956n

ó

2 -12.

tubes.

is capable

Audio

The

of

final amplifier

of

30

to 10,000

er

Re

( f figure

be

to 9'

those

applied

measured

tune -meter

807

utilizing

selector

90

6Á5G

DRIVE

Driver

_audio__

modu-

t

s

cps.

2 -13.)

to the

807

R

and

Modulator

'switch. When the

"807

the

-indicate the

termediate

plate" position

voltage on

amplifier

selector switch

the filament

one of the power

volts meter

meter selector switch

810

..POWER

Schernatic

tune

stages.

in

the "Final

amplifier

is

AMP. .. .

IIr7

-meter

the

filament

the

oscillator,

will

tubes.

in

the "Mod.

era

POWER

118

o-o

RECTIFIER

.

selector

With

Amp.

indicate

switch

volts

meter will

buffer and

the

tune

Plate"

the

voltage

When

Plates

the
Loading"

BIO

POWER AMP.

is

in-

-meter

position

tune

ANT.

148

in

of

-

144

27

30

114

115

160

160

ODQ9Q

34

147

160

\oE

147

118

b

-oE

2 -9

116

---.

147

BASG

AUDIO

6J5

AMP.

Figure

6Á5G

AUDIO AMP.

6J5

2 -13.

AUDIO

DRIVER

Metering

910

MOD.

147

Circuits

s

www.americanradiohistory.com

Section 2

THEORY

OF

OPERATION

position

age

"Mod.

the

former,

the filament

on the remaining

Plate

1"

voltage

across

Item 31. To

modulator tube

in the

of the oscillator

mounted

"Mod.

in

Plate

the 40F

the 6L6 buffer

switch.

cathode

tubes

on meter

circuit

the

and

can

"807

6J5

Item

can be

audio

15, in

current of

be read

Item

grid"

volts meter

position

the

check

place

2"

can

be read

Unit.

can

be read

the

the

at all

140.

The

read

with

position.

driver

will

power

amplifier

the filament

modulator

the

voltage

the

tune-meter

position.

The

by the meter,

The

cathode

with

6L6 cathode

807 intermediate

times,

without

intermediate

the

test

The

6A5G

tubes

cathode

read the

tube.

voltmeter

filament

on

selector

cathode

current

the

test

position.

switching,

amplifier

meter

switch

audio

current

volt-

In

the

reads

trans-

the

other

switch

current

Item

203,

of

meter

The

amplifier

grid

in

amplifier

is read

with

cathode"

the

power

meter,

amplifier

141.

modulator

000

ohm resistors

age

meter.

; with

_Plate

current

antenna

meters

oscillator

are

mounted

the

cabinet.

the

test

positions

Item

is

The

plate

is read

the

tune-meter

1"

and

is

read

current

with

cathode

meter

respectively.

amplifier

142.

The

metered

voltage

with

are in

The

modulator

"Mod,

with meter,

is

the

exception

current

on

the

switch

is

metered

cathode

at all times

of the power

meter, Item

series

selector

Plate 2"

read

with meter,

and

meter

panel on

in

the

"6J5

The

grid

at all

current

with

of the

meter,

amplifier

145.

with

this plate

cathode

positions.__The

Item 148.

switch

current

in "Mod.

The remote

Item

of those

the

measuring

r-f

line

the front door

and

current

times

power

Two

is

r-f

143.

current

6A5G

of

with

Item

and

100,-

volt-

read

line

All

the

of

2-10

www.americanradiohistory.com

INSTALLATION

AND INITIAL

ADJUSTMENTS

Section

3

I- INSTALLATION.

PRELIMINARY.

a.

UNCRATING. - Caution should be

(1)

uncrating to avoid

:ven

A nail

instead

inspected

make

spect each

all controls

operation as far as

application of power.

be filed promptly

puller

of

should be used

a hammer or

carefully. Inspect

sure that

all cable

unit for loose

such

as switches,

with the transportation

INSTALLATION

damage to the equipment.

remove the

to

All

bar.

units should be

cables and

connections are tight. In-

and

dials,

etc.,

determined

for

damage should

bolts.

cán

be

All

screws

claims

SECTION

AND INITIAL

used

nails

wiring and

Check

for proper

without the

company.

3 '

b.

INSTALLATION

(1) LOCATION

location

is

a

minimum

the

transmitter

minimum

the

of

(2) SETTING

transmitter

units

as well

moved from

no

attempt be

41

39

32

z

ADJUSTMENTS

OF TRANSMITTER.

of the

transmitter should

clearance

permit

to

clearance

transmitter

of

36

to

allow the

UP TRANSMITTER.

is shipped

as some of

the

cabinet. It

made

to

PROCEDURE.

be

such that there

30

of

inches at

free circulation

inches is

required in front

door to

the

with

the more

place

heavier

fragile

'reconiriiended

is.

these

components in

- The

the rear of

air. A

of

open.

- The

iron

parts

core

re-

that

ANTENNA

TRANSMISSION

LINE

OPENINGS

FOR

POWER

1. AUDIO

CONDUITS

¡

DUST

COVERS

FRONT DOOR

n4

f

1 I

f

36

BOTTOM

VIEW

Figure 3 -1.

www.americanradiohistory.com

Floor

Plan

for Installation

3 -1

Section 3

INSTALLATION

AND

INITIAL

ADJUSTMENTS

3 -2

1-2.

300G Transmitter

www.americanradiohistory.com

-

Pear. ViAi

Too