Gates Bc-1t Instruction Manual

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iJC-1T

IN..,TrWCTION

BCOY

-'•

it

!'~S•.

TrF,!t ·,O'

IFli·,D

r·o~

COf'E.LHAD

OP1

'.,h/

,'I'ION 640KC/

,~5rJKC

-

C8-

?':

7

1'hi:-- c•t~nd ·

,rd

RC-1·?·,

1000

.

att

broad

ca.

t · er

nsmittf!'r,

has

b

en

mo<

ified

to

OD~t"Rt

on

th

Conelr

d

requency

of

640

KC. The

rh1nge

from

P'iQ

tr,

thfll

r-e

.~

1

l

larly

used

broad

ca

t,

fre'1ueney,

o

ths

Conelr~d

fr

quency

o

6M) K ·

•,

.srr.omoliRhed

pr&cti

•.

lly

in.

tant

neously

by

the

operat

on

of

e,.

_v

ral

RF

relays

•ithin

the

transmitter.

These

rel

vs

are, . 11 ·~ctu~

ted

h:,

me

.n~

of

r

n~

lever

r-w

itch

located

on

r,

,e

right

.:rn;j

s

de

o

th

,

t:r

n~-

mit

t~r

ad

Jac

~~t

to

th

to

molula~or

Li·s

control•

• A

nee

indicating

l,

.

.u1

,..

lncat-.ed

iust

&

hove

the

swi.

ch

i~

lit

when

the

freou•ncv

r i an,,-e

re-

]

.':t

y

are

in

tEe-

fe

6

ul

!.

·

posi

·ion.

· · 1

!..

.1Sl

:c..

tAl. vPr,n.-d"ING Pk.O(.;""lJUh.l -

..

In

0r

~r

to

1

·t

?.ntan~ou_ly

c

b·,

m

g~

from

one

frequer:cy

,o

an0

·

h,,r,

ne

BG

- " T

tr;;.r.-:;,r,itt"'r

ha

b

e1

~

"'.1~ified

a~

follows

-

-h

gecond

os.iJJ-~tor

ur.it

(:·~422

~icts

\

ef>n

jn-t

Jled..i.

An

ah1~-:i.:.11um

sh

lf

has

t "'en

mount

en

across

the

j n,..j

de

front

of

the

t.ransmi

t,PJ"

nd

on

hie~

shelf

thP.

Conelrad

oscillator

nc

the

re

6

7.1lar

fr•quen.y

orcil-

lator

{d

)O!~

C)

a re

rlac

d.

The

regu

ir

o~cilla

tor

normal

1

y

i::

loc-

....

d

on

th

. c .:s.,iel

an,j

!:'helf

arsl'!rr.lily.

It

has

o~

_n

r

moved

::\nC.

i.

mo1rnted

~

on

the

right

s

ide

of

the

ho~iz01tal

~helf.

The

Conelrad

o~cillator

i

to

t.h

e

lt<>ft

of

t,h

~

rep;ular

oscj

llc1

or,

on

the

same

shel

r.

'I'

.ese

osciJlar,or

make

u

of

cahles

which

are

pl•1gged

into

the

bac

·

side

ot

the

oscillator

cha

sis.

Thh·

makes

for

easy

r~:nov

J.

of

each

oscil

~tor

for

ser

icin~,

if

n~ceesary.

A11

fr-

quency

control

relays

a ·e

ener

izPd

by

th_

two

S"'t.s

of

cont·lct.s

which

:'Art'!

a

pa.rt

of

+..,he

latchinf

r

lay

Kl6.

Thii

late}

L

,?..

relay

L,

locat-ed

on

the

panel

and

she

f

assembl

y ,

on

the

right

hand

sir!e

of

tho

tran.

rr.itter,

ju

t,

below

the

os~illator

shttl.f.

Two

set

of

3inv,1e

,

ol

doubl

throw

contacts

on

this

latchin

g

rely

do

the

energi2ing

of

each

separa

e bank

of

frequency

s~l~ctor

reldy~.

The

coils

of

this

l

tchtng

r~J

y

are

energized

by

230

volts

AC

which

:ivailable

th1

ough

th~

lev

r

s~l~

tor

switch

Dq/,..9Al

if

th

0

filament

circ

1

J;\t

of

the

EC-1T

tran.,rr.it

t

is

de-energiz"d•

. A

pa

rof""norr.1aI!y

c!o-ed

contact"on

the

filam

n€

start

el~y

Kl

re

in

series

with

230

vols

AC,

the

lever

selector

~wi~ch

S9

1

S9A

~nd

the

coils

of

latchi

g

rAlay

Kl6.

If

the

filaments

ar~

off•

the

opera

ion

of

the

sel~ctor

switch

S9/S9A 11 entr-r ,

ize

on~

of

the

coils

of

the

latching

relay

16

{either

for

Coni'!lrad

or

regular

frequ

ncy),

t

lis

in

turn

will

rn~chanically

latch

n a

set

of

ontacts

which

will

cl

ce

th

AC

230

volt

circuit

to

ne

of

the

two

frequency

chan~e

bank

of

RF

relays.

(Thls

ci

cuitry

is

shown

on

overall

~chematic

C7:~o.,O

included

1

.-.1

1-

th!

s

nstruction

book.)

Bear

in

mind

it

is

imno~sj

J

~

to

chan

•

o~

rgti

~

f

enuencv

of

this

r&

emitter

wnile

the

oiat

or

ilam~nt

cir-

c~1

1~

en

r~ized:

This

Proc~dure

was

inco

o

·ated

to

make

the

ooe

a-

tin

fool-?r-oof,

it

cannot

be

swit,chr>d

with

any

h1

,h

voJ

age

apolied

,o

the

vario

cir

uits

of

ne

transmitter.

This

prec

udes

the

cossi-

bili

y

of

a-cin

co~tacts

•

.

,:

)

KC

oneration

th

following

rel

y

will

be

er

t'!r

~ized,

,

O,

'

'-' -

,.,

I

Tne~ r

lays

h

ve

en

~elected

by

the

op

r

tlo~

of

h

t

tr

n

,1

ter

filurn

n.

c

rut

d

-en

r_

z~d

at

~h

i

...

-

www.SteamPoweredRadio.Com

..

S9A

op.rat'on.

The

function

of

each

relay

of

this

group

will

be

d-

cr·ted.

1-lelay

K8

Is

-

used

to

swi

t

ch

the

two

o

ell

la

tor

units

that

are

a

part

f

thi

transmitter

into

the

~rid

circuit

of

the

6BG6G

RF

driver

sta~e.

A

set

of

double

pole,

double

throw

con

actn

perform

two

switchin

functions.

With

K8

nergized,

on1?

iLt

of

contact

connects

the

s:

0

KC

oscillator

unit

output

to

th(:;

i;rid

circuit

of

the

driver

sta

.,

,

as

m.

n-

t

ioned

previously,

the

othE"r

:=:et

of

contacts

switch

the

pla

e

vol

ta

;Je

to

the

850

KC

oscillator

unit.

Physically,

this

relay

is

located

on

th

panel

and

shelf

5

embly,

it

1 on

the

inside

of

the

ri

ht

hq

.

section

of

the

trans

itt

r .

Th

right

side

of

the

cabinet

mus e

remo ed

to

service

this

r

lay.

R

lay

1<9

i

located

just

below

th~

R~'

driver

coil

nd

behind

the

two

RI-,

driver

vari~hle

tank

condenger.

•

This

loc

tion

is

ju

:;t

to

tl.e

right

h nd

side

of

the

oscillator

mounting

shelf,

on

the

inside

o~ he

trans-

mi~ter

car.in~t.

This

relay,

when

ener

ized

or

S50

KC

operation

co -

n

-C

s

the

variable

condenser

C7

and

it

p

dder

corn1ens

r

Cl

5

;_

"'~•c,r.s

th

eoil,

L8

and

when

a.d.'usted,

Will

tune

the

HF

driver

s

a.er@!!

to

~r::')

KC.

Relay

KiO

iR

loc

t

d t

the

1

ft

hand

sid

of

th

P.A.

tank

coil

Ll2

(when

transmitter

i viewed

from

the

rear}.

With

thi~

relay

ener

gir. d

for

850

KC

operation

its

contact

romplete

the

v

riabl

tap

or

rotat

4

n ,

whe

1

circuit

of

th•

PA

tank

coil

Ll2.

This

varia

le

connectj

on

i"

made a a

i

lable

to

the

o

era

or

by

mean~

of

the

un .n.

knob

located

· n

th~

front

panel,

m~rked

P.A.

Tune.

This

control

11~ s

th

P.A.

coil

to

be

tuned

to

r~sonance

at

P50

KC,

th~

re~1lar

operating

frequ~ncy.

Rel

y

Kll

is

locat

d

in

a

row

of

relays

t

the

very

ton

of

Uie

cabinet

and

is

available

for

servicing

by

removing

the

rear

cabinet

cover.

T1is

relay.

when

energized,

compl~tes

the

RF

c

rcuit

bet

·een

th~

output

o

P.A.

t,~1nk

coil

L2

an

the

input

of

load

int

coil

113.

Rely

Kl2

is

located

on

the

in91de

left

hand

ortion

of

he

ca

,

1net,

very

near

the

output

connection

of

coil

Ll4o

Thi~

r~lay,

when

en

r~ized,

completes

the

RF

circuit

between

th

output

of

coil

114

and

the

input

of

modulation

onitor

pickup

coil

Ll5.

en

this

transmitter

is

in

the

S

~orc

''reful"r"

operating

po~it1.on,

the

various

relays

eet

up

the

output

circu

t so

as

to

use

~11

,hen

t-

works ,

hat

are

normally

used

in

the

scanJard

BC-lT

tr4nsmitt

r.

Thi~

network

has

proved

itself

to

t,e

e,ctremely

~atisf

ctory

for

m·

tchin

the

P.A.

tubs

to

he

51.5

ohm

lo~u

and

at

th

same

t1m~

to

di~criminate

~ainst

harmonics

that

might

be

gener

ted

in

the

fin

1

amplifier.

A

small

n

on

indicating

lamp

is

ountPd

irectly

ahov@

the

fre

u~ncy

change

witch

S9/

9A

.

This

neon lamn

is

ener

ized

when

the

witch

·o/

S9A

is

mov!'d o

the

top

nosi

..

ioni

mark

d '

1

Reg.".

Thi-;

indicates

to

h

opera

or

that

the

l

tching

r ,

ay

Kl6

is

in

the

1

51KC

operat

. n

p

sition

and tht'!

transmitter

will

be

ready

to

be

energized

to

produce

]

ro

w·tts

carri

rat

thi

frequoncy.

T .,

no

...

nal

tuning

proc~dure

wi

1 b

followed

s

described

in

the

stan-

~

d

rd

1n

truction

book

for

opP.ration

o

this

transmitter

on

~~O

KC.

or

oper~tion

on 640

KC

the

Con_lr

ft~que

cy,

th

rel1ys

mention

d

abov

d

.-en

rgized.

At

1-,he

s

me

im~

rel

ys

Kl3,

Kl4

and

Kl5

will

n n

.t

1is

c<1rni:ination

of

E!nt'rg·

'."..ed

and

d

-energi

zed

relay

1.,'-2277

www.SteamPoweredRadio.Com

..

w

11

t

natle

h

trans:rit:ter

to

instantan~ouslr

develop

1

r:,,;

(')f

:)lJr:,

,

,ut

c,~r

Gn

6l0

KC

.

In

the

following

pdragrarhs

a

descrip~ion

of

t

~e

elar~

ac~ion

or

640

KC

operation

wtll

be

de·cribcd.

e

Oscill

tor

c

ange-ove

r

relay

K8

i~

de-enerr,izad

.

In

thi~

position

thr-

dou'"1

l e

oole

doubl

throw

set

o.i.

contacts

have

disconnected

the

:~50

KC.·

oscillator

power

nd

output

circuits

and

have

now

set

,rn

th

clrc'..d,t

J

of

the

,.o

KC

oscillator

.

This

6 0 K

outp.1t

ir

heint~

fed

into

thP

~rid

circ·

it

of

the

,

.RF

driv

r

sta~e

.

'

rhe

RF

driv

r

ank

cond

nser

change-over

relay

K9

is

de-energiz

d.

Thi::'

automaticat

1,

cUeconnects

C7 anc

Cl5

and

1

th

ir

plac~

the

V.:iri

nle

condrmser

C26 and

padding

conden

er

G27

havft

been

comP.~teL

Thdse

condensers

will

tun

the

RF

buffer

coil

1$

to

the

Conelr!ld

fr

-

qu

ney

of

640

KC

. Once

these

cori<lensers

a e

')rop(~rly

tune

i

t.

.is,

of

cc

urse

, no

:-,robl

m

to

~wi

td·.

from

850

KC

to

640

KC

im,-n(

dia

·.el

v t

ean

of

relay

K9

.

In

the

power

amplif

i

er

St>

C

tion

of

the

transmitter,

t h

(~

relny

KlO,

Y.ll

and

K12

t,ave

been

de

-

energized

.

A:,

the

sarn.e

time

relays

Kl3

1

Kl4

and

Kl~

have

b en

ene

r

ize

d.

Thi~

relay

act.ion

sets

up

the

am

_

l1fier

for

640

KC

opt-ration.

It

will

't

.

noted

that

f or 640

KC

op,..ration,

the

ot..t

...

rut

circuit

configu

r

ation

has

been

simplif1Pd

to

just

a

common

ttFI•,

3ljpht

tuning

of

this

ci

rcu

i t

is

pos

itle

by means

of'the

s~ries

n-

ductor

Ll6,

the

knob

of

which

js

loc

~

ted

at

the

v ·

ry

top

of

~1e

ca

btnet

nenr

th~

door

~top

.

Rel

y

Kl0

i~

de-energi.zed

.

This

opens

the

variable

coll

:,

r.c.,i't

circuit

and l l ows

the

coil

inductance

to

be

increased

ae

now

thP.

ircuit

mE:Ak

s

u

se

of

th

e

ad

di

ti

on

al

tu

rn

s

which

are

betwe

n

he

var

.

~a

t

l~

wh~,.J I

ap

and

the

C

on

el

rad

f i

xe

d t

ap.

(Late

r

on

,

the

inform

-

3.tton

for

loci:.ting

this

tap

will

be

given

.)

Relays

Kll

and

Kl2

are

de

-

,mere;ized.

This

action

automat1cr1.J

y

dL

-

conn

ct

11'3,

Ll4.

ClJ

and

C_J4

from

the

output

circuit

.

The

~ner~ized

relays

Kl3,

Kl4

anJ

Kl5

now

set

up

the

outru

circ

u

it

for

operation

on

th~

640

Y.C

Con

lrad

fre.quen

Yo

Kl3,

bt!!!ing

P.

er-:;i.1,ed

now

conn<~cts

Cl~

And L16

acros

, e nor-i,a l

P.A.

t,ank

coridens

rn

Cll

"'nd

Cl:2.

Th:is

adds

another

ao,rox1mate

2~0

1nmfd.,

to

the

VrllUEI

of

P.

A.,

t .k

condensers.

As

t.r

1

ere

wer

two

400

mmfd.

conr\('n:.;"!rs u

.:

ed

f'

o 810

KC

1

this

makea

10w

a

to

al

cap

c-i

ta

nee

of

.0010)

mf

d.

used

f

or

,

.,.

.J

KC.

This

approx

:i

r.iate a

,t

c,.

"

of

10

.

or

the

P.

A

..

R

lay

flt

1-

~ne:gized

hich

places

the

loadin~

c~

ndonuer~

Cl6

and

Cl?

into

rne

•>utpit

cjrcuit

.

These

-::ondensers

w r s e

lec

t.

ed

o

.:-·ti

,.,

:·1c

)ri'y

1 ,,d t.r!e

amolifier

into

re

istive

51. 5

ohm

loa

c

l.

If

tL

e ic

tr

l

"orc

,h·

i.·n

oa<i

is

(1iff

rent

than

:;1.5

o

hm

.;

(with

no

ro;:ctanc

t!

v1r

an,

,

!-er-

v-

lu

of

outpu

t

conden

f"

r

":'IU$t

he

H~l,ct

, <l.

PP

· y ¥ l

:"

i.i:-.

ene

gi

ed

which

co

mpl0tes

th

e o,1t

;,

ut

ci

.r<'uit

to

th"'

e..:ter

&

:1

.F.

loH

~.

t'

~~~

comol~t~s

the

~Pqu~nce

of

op~ration

~or t

he

varic

u~

r•l

ye

th

3t

are

u~

j

in

~~i1

tr~nfmitt~r.

C':.;

-

2277

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r back on

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• 550

to

6oo

ma.

'lt

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round

2t

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·o t s .

his

would

b . a

normal

in

ut

for

the

onelrn1i,

1/

JO

~C

i:

os

l.;

·or.

Slie;ht

tu

ing

adjustm

nt

c

n

be

rn&de

by

varying

th

i,

.:.

du

ctor

Ll6.

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ariou

s

,...elays

d

othPr

compon"nts

h

ve

een

atfe<

uat~

y •-

;te

r

ell)

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conform

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the

ov

•r

11

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s '

~ma

-1

,

dw

_

g;

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-"

6,

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:

md

tc

h~ a,

.-

ditior.a}

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.s

ljst

that

s

p~rt

of

this

instn1ction

book.

For

s1-i1

p

't

nent

the

v

rious

rel

ys

and

oth

r

com

.nent

hav•

be

r,

·

1ea

do~!

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...

. u

p_

o• ·

teci

by

packinv

111ateri·

l.

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sure

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chec

th..,

compl

te

trana-

'

itter

:rnd r move

11

o"

th

mat~rtal..

Check

thorou~

,

hly

at

the

ve

top

of

the

tran

mitter

i

the

~n

compar

ment.

www.SteamPoweredRadio.Com

ADDENDA

0HEET

BC-1

T

TR,L\JM.ITT

.£R

WITH

CONELRAD

SWITCHING

CS-2277

C28,

P.A.

Padder

for

Conelrad

frequency

has

been

removed

for

shipment.

It

will

be

necessary

to

remove

the

Fan

Assembly

in

the

top

of

the

trans-

mitter

to

install

this

capacitor.

This

transmitter

is

equipped

with

silicon

rectifiers

per

customer's

specification.

2/28/61

GATtS

RAJIO

COMPANY

QUINCY,

ILLINOIS

www.SteamPoweredRadio.Com

•

;1.

DD

EN

DA

,3

H

£~

T

For

BC

lT

:B;or

BC

500T

Reference

833A

Tube

Handling

The

Ga

tes

BC

lT

and

its

compa

n

ion

transmitter

the

BC

500T,

use

83

3A

power

tubes

in

the

modulator

and

power

amplifier

stages.

These

are

of

the

single

wire

or

thread

filament

type,

as

com-

pared

to

othe

r

tubes

that

may

have

the

filam

e

nt

(heater)

con-

tained

in

a

tube,

which

is

com11only

called

the

cathode

assembly

.

Tubes

ha

ving

filam

e

nts

su

pp

orted

by

springs

(such

as

the

833A)

require

more

than

normal

car

e

in

handling.

These

filament

wires

are

easily

broken

by

sudden

he

avy

vibration.

At

all

tim

e s

han-

dle

the

tubes

with

care,

until

they

ar

e

safely

ins

e

rted

in

the

tube

sockets

of

the

transmitter.

At

this

point,

more

car e

is

required

as

the

two

filament

prongs

are

also

the

me

ans

for

securing

the

tubes

in

the

transmitter

.

l"iake

sure

th

e

conn

ec

tions

have

some

"give"

so

that

no

u

..

~

due

strain

is

p

l~ced

on

the

glass

to

metal

seal

. As

these

tubes

do

expand

a

bit

during

op

e

ration,

the

two

securing

filam

e

nt

connec-

tors

must

be

able

to

mov0 a

bit

themselves

.

Tak

e

car

e

when

making

the

grid

and

p

late

conn

e

ctions,

do

not

put

any

undue

strain

on

th

ese

connections

also,

during

tube

installation.

Of

cours

e

the

connections

of

th

e

grid

and

plate

should

b e

fl

e

xibl

e

to

al

low

for

expansion

of

the

tube.

For

shipping

or

storing

it

is

a

dvisable

to

us

e t he

packing

material

and

ca

rton

that

the

tube

was

shi

p

ped

in

from

the

tube

manufac-

turer.

·

Following

th

e

se

reason

a

bl

0

precautions,

ther

e

should

be

no

trouble

in

handling

th

ese

tubes

•

2/17/61

-1-

www.SteamPoweredRadio.Com

I -.

L

.

BC

-IT,

BC500T,

BC250T

A.M.TRANSMITTERS

www.SteamPoweredRadio.Com

•

INDEX

Page

AIR

FILTERS

........................

.

..

.

.........................................

;........................

7,

9

ANTENNA

COUPLING

••••......... .

.........

•..•..

..

.....

..

•

............

...

.. ...

••

.••••.

...

.•

.....

..•.•

7

AUDIO

INPUT

.............................................................................................

3

CRYSTALS

AND

ADJUSTMENT

...........

..............

...........

......................

.

..........

Z,

7

DUMMY

ANTENNA

................................................

_.

.....................................

4

FEEDBACK.............

.....

........................................................

..

....................

3

FILAMENT

RHEOSTAT...............................

..

.............

..

.............

......

.........

7

FLOOR

WEIGHT

..

.............

..

... .

...

...•..

......

..

.•.

..

.

..

.. ...•

..

..................

...

..

.

..

...

.....

. l

FREQUENCY

MONITOR

..............

•••

..................

...

..................................

....

..

. 3

GROUND

SYSTEM

..................................................

.....................................

Z

INTERMEDIATE

POWER

AMPLIFIER.....

..

..........................

.

..........................

3

METERS

....................................................................................................

7

MODULATION

MONITOR

........

.

.........................................................

.......

.....

3

MODULATOR

BIAS

,

ADJUSTING

.................

..

......................................

...

........

3,

6

NEUTRALIZING

..........................................................................................

3,

5,

6

PARTS

LIST

......................................................

.....

................

.

........

.....

......

10,

11

PLATE

RHEOSTAT

.......................................

...

....

............

.

....

...

...............

..

.. 7

POWER

AMPLIFIER

AND

TUNING

...

..

........

....

..

.

...

....

..

...............

...

....

•..

..

.•

....

..

.

3,

6

POWER

SUPPLIES

:

HIGH

VOLTAGE

.........

..

...

...................

:

.........

-..

.......................

.......

....

4

INTERMEDIATE

................................................................................

4

MODULATOR

BIAS

............................................................................

4

PRIMARY

LINE

...........................................................................................

Z

PROTECTION:

MODULATOR

...

•.

...•..

...................

...

........

.................

.......

........

..

.

..

.

...

..

3

POWER

AMPLIFIER

..

...

......

..

....

•

..

.

..

....

..

.

..

.

..........

....

.

..

..........

3

RELAYS...............

.

........................

.

.......................

...........

.......

..

......

3,

7

READYING

CHECK

LIST

.........................................................................

,

..

•

..

4

REMOTE

CONTROL

............

.•

.............

....................

....

...........

...

..........

.........

1,

4,

8

SPECIFICATIONS,

TYPICAL

................

...........

......

....

.......

.

..................

...

..

.....

I

SUCTION

FANS

...........................................................................................

1, 7

TEST

EQUIPMENT

......................................................................................

7

TRANSMITTER

BASE

.............

..................

.....

..

..................

.

..........................

Z

TUBES

.......................................................................................................

1

TUNE-UP

PROCEDURE

................................

.....................................

.....

.•.

...

4,

.

5,

6,

7

VOLTAGES

AND

CURRENTS

................

,........................................................

6,

7,

9

GATES

RADIO

COMPANY

-

Quincy,

Illinois,

U.S.A.

www.SteamPoweredRadio.Com

•

INSTRUCTIONS

FOR

INSTALLING

AND

OPERATING

THE

GATES

MODEL

BC-lT

lKW

BROADCAST

TRANSMITTER,

M5393

IB-869A

In

the

preparation

of

this

instruction

book,

we

have

endeavored

to

be

concise,

yet

thorough.

In

several

places,

symbol

numbers

are

referred

to,

such

as

R 1

or

S 1,

etc.

These

symbol

numbers

will

be

found:

(a)

on

picture

illustrations

in

this

book,

(b)

on

the

wiring

diagrams

in

this

book,

(c)

adjacent

to

or

on

the

part

itself

in

the

equipment,

and

(d)

on

the

Parts

List.

Symbol

numbers

follow

industry

standard

procedure

and

have

a

mean-

ing.

"R"

means

a

resistor

or

rheostat,

"C"

is

always

a

capacitor,

"V"

a

vacuum

tube,

''S"

a

switch,

"K"

is

always

a

relay,

"L"

is

an

inductor,

either

air

or

iron

core,

etc.

As

you

read

this

book

and

it

might

say,

"Adjust

Ll2

to

resonance".

Find

Ll2

on

the

picture,

which

in

this

instance

is

picture

M5393,

and

you

quickly

understand

what

to

adjust

and

also

gain

familiarity

at

the

same

time.

--

You

will

find

this

equipment

a

pleas

-

ure

to

install

and

not

nearly

as

difficult

as

the

length

of

the

instruction

book

might

indicate.

Instruction

books

are

reference

manuals

for

both

installation

and

future

servicing.

IMPORTANT

...

If

this

transmitter

is

to

be

unattended,

i.e.,

operated

by

remote

control,

care

should

be

taken

that

winter

temperatures

inside

the

transmitter

building

do

not

go

below

50°

Fahrenheit.

Mercury

vapor

recti-

fier

tubes

will

arc

back

at

low

temperatures,

often

causing

serious

damage

to

other

expensive

components.

Protective

relays

and

blower

motors

may

also

become

sluggish

under

extreme

cold

conditions.

Failure

to

provide

adequate

winter

minimum

building

temperatures

will

void

the

guarantee.

THE

FOLLOWING

SPECIFICATIONS

ARE

TYPICAL

AND

MAY

VARY

SLIGHTLY

WITH

VARIOUS

MODES

OF

OPERATION:

1.

Rated

power

output

:

1000

watts.

Capable

of

1100

watts

where

directional

systems

induce

losses.

2.

Frequency

range:

1600

Kc

to

540

Kc

at

the

frequency

you

ordered.

3.

Power

input:

230

volts,

single

phase,

either

50

or

60

cycles.

Provide

#4

or

larger

primary

wiring

from

entrance

box

to

transmitter.

Transmitter

will

con-

sume

approximately

4000

watts

at

100%

modulation.

4.

Frequency

stability:

t_

10

cycles.

_

5.

Audio

input:

12

db

f

2

db

for

100%

modulation.

The

output

of

a

Gates

SA-39B

limiter

should

be

correct

for

this.

If

other

limiter

or

audio

amplifier

used,

be

sure

and

check

output

capabilities.

/

6.

Input

audio

impedance:

Ai,

supplied,

600

ohms,

which

will

also

match

500

ohm

impedance.

It

may

be

connected

for

150/250

ohms

if

desired.

7.

Distortion:

Rated

at

3%

from

50

to

10,000

cycles

but

capable

of

much

better

at

many

frequencies.

You

will

be

pleasantly

surprised.

8.

Noise:

60

db

or

better

below

100%

modulation.

9.

Carrier

shift

:

3%

or

less

between

O

and

full

modulation

provided

wire

size

in

Point

3

(above)

is

followed

and

R.F.

load

is

correctly

tuned.

10.

R.F.

output

impedance

:

Will

match

loads

from

50

to

70

ohms.

An

antenna

coupling

unit

ii;

usually

necessary

to

match

the

antenna

tower.

Gates

Radio

Company

OTHER

HELPFUL

DATA:

(a)

Provision

for

2

vacuum

type

crystals

and

holders.

If

you

wish

a

spare,

order

M5602,

giving

your

frequency.

(b)

The

inbuilt

dummy

antenna

will

accept

100%

modu-

lation

and

is

for

51.5

ohms.

See

Par.

4

under

"How

Can

We

Helr,

You?

"

in

the

back

of

this

manual,

entitled

'Computing

Power

Output".

The

dummy

antenna

is

substituted

for

the

tower.

(c)

THE

TWO

TOP

SUCTION

FANS

can

do

their

best

in

cooling

performance

by

periodical

replacement

of

the

removable

air

filters

located

at

the

front

bottom

of

the

transmitter.

Order

Type

M5825

and

two

are

required.

The

time

cycle

in

replacing

filters

depends

on

dust

conditions.

Normally

about

three

times

annually.

(

d)

The

floor

weight

is

800

lbs.,

or

slifhtly

leas

than

100

lbs.

per

square

foot.

Allow

28

'

for

the

front

door

swing.

Size:

78"

high,

36-1/16

."

wide

and

31-7/8"

front

to

back.

(e)

TUBES:

Your

100%

tube

complement

(TK287

if

you

wish

to

reorder)

is:

(2)

(6)

(4)

(2)

( 1)

12BY7A

for

oscill,ator

and

first

intermediate

amplifier.

6BG6G,

of

which

two

are

parallel

operated

as

the

second

intermediate

amplifier,

\wo

are

push-pull

audio

input

amplifiers

and

two

are

cathode

follower

driver

amplifiers.

833A

tubes,

of

which

two

are

R.F.

power

amplifiers

in

parallel

and

two

are

Class

B

modulators.

8008

main

power

supply

rectifiers.

866A

intermediate

power

supply

rectifiers.

5R4GY

bias

supply

rectifier.

I~

you

wish

FCC

spare

tubes,

which

is

-

the

minimum

list

of

spares

acceptable

to

FCC

(TK288

if

you

wish

to

reorder),

these

are:

( 1)

12BY7A;

(3)

6BG6A;

(2)

833A-

( 1)

8008•

( 1)

866A-

and

( 1)

5R4GY.

' ' '

GATES

RADIO

COMPANY

-Quincy,

Illinois,

U.S.A.

Page

1

www.SteamPoweredRadio.Com

INSTALLATION

HINTS

Most

of

us

do

not

like

to

read

instruction

books.

We

have

tried

to

be

as

concise

as

possible.

If

you

are

busy,

take

this

book

home

and

read

at

your

leisure.

We

believe

it

will

help.

Here

are

a

few

suggestions

:

1.

CHECK

YOUR

PACKING

LIST

CAREFULLY

...

Put

as

many

of

the

yet

to

be

used

components

as

possible

out

of

harm's

way.

A

tube

or

crystal

has

been

stepped

on,

even

lost.

2.

HAVE

THE

PREMISES

TIDY

before

going

to

work.

Nothing

quite

so

bad

as

stirring

up

a

lot

of

dust

with

a

vigorous

broom,

to

let

it

settle

on

components

or

be

sucked

into

the

new

air

filters.

3. A

BASE

FOR

THE

TRANSMITTER

...

Look

at

Drawing

A30585

in

the

back

of

this

book.

This

base

can

be

quickly

made

of

2"

x

4"

lumber.

Paint

it

black.

It

becomes

both

a

mop

base

and

an

easy

way

to

get

the

wiring

in

and

out

of

the

bottom

of

the

transmitter.

Lay

this

base

to

the

floor.

Be

sure

the

top

is

level

so

the

transmitter

won't

rock.

-

With

transmitter

on

this

base,

you

can

mop

without

fear

of

water

rust-

ing

the

bottom

of

the

transmitter

and

your

wiring

installation

will

be

easier.

It

will

look

snappy

too.

4.

THE

PRIMARY

LINE

is

important

both

from

the

utility

and

what

you

install

in

th

.e

building.

Your

transmitter

operates

on

230

volts

and

service

should

be

for

4000

watts

at

least.

But

don't

for-

get

that

th

.e

utility

company

will

probably

provide

the

same

entrance

cables

for

tower

lights

and

all

your

other

equipment

even

if

for

115

volts.

Talk

this

over

with

your

utility

company

and

be

sure

service

is

ample

-----

to

be

sure,

more

than

ample.

We

suggest

#4

wire

from

your

entrance

box

to

the

transmitter.

The

utility

company

may

prefer

larger.

5.

A

THOROUGH

INSTALLATION

.•.

Don't

rush.

We

know

new

equipment

is

tempting

but

a

day

or

two

longer

in

installation

will

pay

big

dividends

later.

Dress

wiring

nicely.

Use

plastic

tape

over

any

entrance

wire

that

might

look

like

it

could

bump

against

something

else.

6.

THE

GROUND

SYSTEM

.•.

Don't

overlook

the

most

important

thing

of

all

- a

2"

copper

strap

from

your

transmitter

to

where

the

ground

radials

join

together

under

your

tower.

---

It

has

been

over-

looked.

7.

HOW

CAN

WE

HELP

YOU?

Read

Par.

27

under

"How

Can

We

Help

You?

"

in

the

back

of

this

book.

It

may

save

you

some

rerouting

of

wires

in

case

you

might

have

forgotten.

GETTING

READY

..•

For

shipment

all

tubes

and

vacuum

enclosed

relays

are

removed,

relay

con-

tacts

blocked

and

tied

and

other

parts

tied

down

to

prevent

damage

during

shipment.

Power

ampli-

fier

RF

choke

L9

also

has

been

removed.

The

connector

straps

have

been

adequately

tagged

for

easy,

correct

re

-connection.

Coil

L 13

located

at

top

rear

of

cabinet

has

special

mounting

brackets

for

shipping.

These,

along

with

all

other

packing

material,

string,

tape,

etc.,

should

be

removed.

The

front

door

of

the

trans

-

mitter

has

been

mechanically

supported

to

the

cabinet

for

shipping

safety.

Remove

this

support.

All

relays

inspected

for

free

travel

of

armatures

and

contacts.

Heavy

components

such

as

the

power

and

modulation

transformers,

and

filter

reactors.

are

not

removed

for

shipment

but

mounting

bolts

should

be

re

-checked

for

tightness.

Tubes,

crystals

and

the

vacuum

time

delay

relays

are

removed

for

shipment.

Go

over

the

transmitter.

After

riding

a

long

distance

a

bolt

could

come

loose.

Put

a

screw-

.

driver

or

wrench

to

all

available

nuts

and

bolts.

It

may

take

an

hour

and

again

save

many

head-

aches

later.

While

doing

this,

look

over

wiring

connections

as

you

go~

Look

at

terminal

strips,

or

in

essence

--

do

the

same

thing

your

auto-

mobile

dealer

does

when

he

receives

a

new

car

from

the

factory,

go

over

it

from

stem

to

stern.

8.

KNOW

YOUR

TRANSMITTER

.•.

After

assembly,

let's

take

a

little

time

to

become

familiar

with

it.

The

following

may

help

as

you

observe

it

:

(a)

Most

of

the

low

power

radio

and

audio

frequency

components

mount

vertically

on

an

aluminum

panel

and

shelf

assembly,

to

the

right

as

you

open

the

front

door.

This

is

reached

from

the

inside.

You

may

remove

the

right

side

of

the

cab-

inet

to

expose

the

wiring.

(b)

At

the

top

of

this

assembly

are

the

four

833A

tubes.

Thus

both

RF

and

audio,

the

circuit

starts

at

the

bottom

and

directs

toward

the

top.

Note

one

of

the

suction

fans

is

directly

above

these

tubes

to

instantly

remove

the

hot

air.

(c)

The

cabinet

ceiling

holds

the

power

amplifier

tank

and

loading

components.

The

aluminum

chassis

holding

these

components

is

well

perforated

for

heat

release.

The

second

suction

fan

keeps

a

steady

up-draft

for

cool

opera-

tion.

(d)

Heavy

components

are

in

the

bottom

of

the

cabinet

where

air

is

coolest.

(e)

Air

filters

just

below

the

front

door

may

be

removed

and

changed

without

turning

off

the

transmitter.

Change

air

filters

when

you

can

no

longer

see

through

them

when

holding

up

to

a

ceiling

light.

You

can

brush

off

heavy

accumulation

of

dirt

and

dust

to

add

to

their

life.

(f)

With

the

perforated

inner

shield

just

behind

the

front

door

in

place,

you

can

see

essen-

tially

all

of

the

·

internal

transmitter

without

turning

it

off.

When

you

remove

this

per-

forated

shield

or

door,

you

disengage

the

interlock

switches,

turning

off

600

volt

and

_2500

volt

supplies.

NEVER

strap

out

interlocks.

Your

life

is

valuable

and

memories

are

short.

9.

DUAL

VACUUM

MOUNTED

CRYSTALS

may

be

mounted

in

the

oscillator

unit

near

the

bottom

of

the

vertical

panel

mentioned

in

(a)

preceding.

Crystal

changeover

switch

(S

1)

and

frequency

trimmers

(Cl

and

C2)

operate

from

the

front.

~scillator

tank

is

untuned

and

lightly

couples

to

the

12BY7A

first

RF

stage,

also

part

of

the

oscillator

chassis.

Crystals

are

low

tempera-

t~re

coef~i~ient

type.

Very

low

crystal

current

aids

stab1hty.

Frequency

trimmers

Cl

and

C2

are

touch

up

frequency

adjustments

for

each

crystal

both

for

aging

and

initial

tune-up.

The

first

intermediate

stage

is

tuned

but

the

crystal

oscillator

is

not

tuned.

Page

2

GATES

RADIO

COMPANY

-

Quincy,

Illinois,

U.S.A

.

a

www.SteamPoweredRadio.Com

•

10.

FREQUENCY

MONITOR

is

connected

at

the

oscil-

lator

unit

to

terminal

#27

and

ground

.

See

Draw-

ing

C-78180.

The

Gates

M4990

monitor

is

an

excellent

companion

instrument

to

the

BC

-1

T

transmitter.

Plate

voltage

for

the

oscillator

unit

is

from

the

600

volt

intermed

i

ate

supply

through

resistor

R9.

11.

SECOND

INTERMEDIATE

RF

AMPLIFIER

has

two

6BG6G

tubes

in

parallel.

These

relatively

new

husky

tubes

ha

ve

600/650

plate

volts

applied.

Current

will

run

150

to

200

MA

for

both

tu

bes,

varying

as

to

frequency

and

load.

Current

indi-

cates

on

the

multimeter

when

the

multimeter

selector

switch

is

set

at

"RF

Driver

Cath

. "

Above

1050

Kc

no

tank

padder

is

used.

Belo

w

1050

Kc

a

padder

is

provided

,

see

Chart

A30604.

Multimeter

switch

position

"RF

Driver

Grid"

will

indicate

grid

current

0.3

to

0.5

MA,

which

is

normal.

The

plate

and

screen

voltage

of

this

stage

are

modulated

about

10% .

This

causes

grid

drive

to

the

final

power

amplifier

to

in

-

crease

under

modulation

,

improving

linearity

and

reducing

distortion.

12.

NEUTRALIZATION

is

only

required

in

the

power

amplifier.

Neutralization

of

the

power

amplifi

e r

is

accomplished

by

the

out

of

phase

volt

a

ge

be

ing

obtained

from

the

6BG6G

tank

coil,

LB.

Several

taps

brought

out

adjacent

to

the

electrical

center

of

this

coil,

these

taps

affording

rough

neutral-

ization

.

By

means

of

the

variable

neutralizing

condenser

C 10

and

these

taps,

it

is

possible

to

completely

neutralize

the

two

833A

tubes

in

the

power

amplifier.

The

neutralizing

condenser

C 10

can

be

adjusted

from

the

front

of

the

trans

-

mitter,

by

use

of

a

screwdriver

working

through

the

small

aperture

in

the

lower

right

side

of

the

upper

front

panel.

13.

POWER

AMPLIFIER

consists

of

parallel

833A

into

an

"L"

and

two

"T"

sections,

unusually

effective

as

to

efficiency

and

harmonic

reduc

-

tion.

Refer

to

Drawing

C78180.

Coils

Ll2

and

L

14

are

variable

tuned

coils

for

resonance

and

loading.

Other

than

the

neutralizing

condenser,

there

are

no

variable

air

condensers

used

in

the

power

amplifier,

which

adds

greatly

to

reliability.

Grid

drive

to

this

amplifier

(multimeter

switch

position

"Power

Amp.

Grid")

should

be

at

least

100

MA

for

good

operation.

Higher

grid

drive

to

150

MA

is

acceptable

but

will

vary

as

to

frequency.

14.

POWER

AMPLIFIER

TUNING

...

Tank

circuit

is

tuned

by

variable

tank

coil

Ll2

(Drawing

C78180).

Two

Type

G2

mica

padder

capacitors

in

parallel

for

the

tank

circuit

vary

in

size

as

to

frequency,

as

do

loading

mica

capacitors

C 13

and

C

14.

-

Please

consult

Drawing

A30604

in

this

book

for

values.

The

correct

values

are

supplied

for

your

frequency.

Power

amplifier

plate

current

will

vary

from

525

MA

to

600

MA.

Plate

voltage

will

indicate

near

2500

volts.

The

tank

coil

is

tuned

by

the

large

knob

marked

"P.A.

Tune"

and

the

output

tuning

for

load

is

marked

"Loading".

15.

MODULATION

MONITOR

operates

from

pickup

coil

L15

(Drawing

C78180)

and

connects

toter-

minal

strip

TB2.

The

RF

line

ammeter

is

the

last

component

prior

to

the

antenna.

The

Gates

MO-2639

or

M5693

modulation

monitors

are

ex-

cellent

companion

instruments.

16.

POWER

AMPLIFIER

PROTECTION

..•

Overload

is

guarded

by

relay

K6

located

near

the

833A

filament

transformer

T9.

With

semi-variable

shunt

resistor

R2

l

and

adjustment

is

possible

for

desired

overl9ad

tripping

of

the

relay.

As

factory

adjusted,

trippilng

point

is

at

700

MA

or

about

20%

over

normal

opera-

ting

current

of

the

power

amplifier.

Relay

K6

actually

controls

master

overload

relay

K3,

which

when

open,

disconnects

the

main

power

transformer.

17.

AUDIO

INPUT

is

connected

to

terminal

strip

TB

1,

ter-

minals

29

and

30,

and

is

wired

for

500/600

ohms.

If

150/250

ohms

is

desired,

change

input

transformer

connections

on

transformer

T6

(Drawing

C

77711)

by

breaking

the

jumper

between

3

and

4

and

connecting

l

to

3

and

4

to

6.

In

testing,

distortion

can

often

be

improved

by

adjustment

of

variable

control

R3

lo-

,/

cated

on

the

audio

printed

wiring

formica

board.

As

no

improvement

would

be

noticeable

to

the

ear,

if

t

est

equipment

is

not

available,

set

R3

at

mid-point.

Cathode

current

for

the

push-pull

6BG6G

first

audio

tubes

is

indicated

from

5

to

10

MA

on

multimeter

switch

position

"Input

Audio

Cathode".

No

meter

readings

are

taken

on

the

second

audio

stage

as

their

operat

i

on

controls

the

bias

to

the

modulators

and

the

proper

operation

of

the

~odulators

indicates

proper

operat

i

on

of

this

stage.

18.

MODULATOR

BIAS

is

adjusted

for

each

833A

modula-

t

or

by

controls

R 1

and

R2

located

on

the

inner

front

panel.

These

controls

vary

the

operating

constant

of

the

cathode

follower

driver

stage,

causing

a

bias

change

on

t

he

modulators

by

causing

a

voltage

change

at

resistors

R

11

and

R 12

in

the

cathode

follower

stage.

This

effects

extremely

smooth

and

accurate

modulator

bi

as.

Modulator

static

current

(no

signal

to

audio

input)

s~ould

read

about

40

MA

per

tube

as

adjusted

by

the

·

bias

controls.

Below

the

modulator

bias

controls

is

a

3-position

switch.

Left

position

"Modulator

l"

and

right

position

"Modulator

2"

indicate

individual

current

of

each

modulator

tube.

Center

or

"Total"

position

indicates

both

tubes

and

this

position

is

used

for

normal

broadcasting.

Total

modulator

current

wi

ll

indicate

from

350

MA

to

500

MA

during

heavy

modulation.

Reliance

on

modulator

currents

is

of

negligible

value

and

the

modulation

monitor

is

the

only

reliable

indication

regardless

of

modulator

current.

19.

MODULATOR

PROTECTION

operates

through

over-

load

relay

K7

provided

with

semi-variable

shunt

resistor

R22.

Factory

adjustment

is

for

700

MA

tr~pping

even

though

currents

substantially

under

this

would

be

normal.

This

is

so

a .

quick

modula-

tion

peak

will

not

put

the

transmitter

off

the

air.

Re~ay

K7

operates

with

PA

overload

relay

K6,

which

controls

relay

K3

to

de

-energize

plate

contactor

K2,

turning

off

the

high

voltage

.

20.

FEEDBACK

.

..

Fourteen

decibels

of

feedback

from

modulat?r

pl3:tes

to

firs

_t

audio

grids

adds

greatly

to

low

~1s

tortion

and

no1s

e

readings.

The

feedback

ladder

1s

on

a

printed

wiring

formica

board

directly

above

modu

_

lation

transformer

T3.

Altering

the

con-

stants

of

this

feedback

ladder

will

seriously

effect

performance

specifications.

21.

RELAYS,

including

fuses

and

time

delay

relays,

are

located

at

the

bottom

of

the

vertical

aluminum

panel

and

shelf

assembly,

except

relays

K6

and

K7

located

ne

,

ar

the

833A

filament

transformer.

Fuses

F 1

and

F2

are

30

ampere

cartridge

type

and

this

block

ac-

commodates

the

230

volt

primary

line.

Fi~ament

contactor

K 1

is

energized

by

filament

start

s_

witch

S5

beneath

the

multimeter.

This

starts

all

filament

transformers,

the

heater

for

time

delay

relay

KS,

and

the

bias

power

supply.

Allow

about

30

seconds

for

time

delay

relay

operation.

When

GATES

RADIO

COMPANY

-

Quincy,

Illinoi

s ,

U.S

.A.

Page

3

www.SteamPoweredRadio.Com

zz.

the

time

delay

relay

closes,

this

turns

on

the

intermediate

power

supply

and

the

bias

power

supply.

The

door

interlock

must

be

clos~d

before

these

supplies

operate.

Also

the

high

voltage

time

delay

relay

K4

is

energized

and

will

permit

turning

on

high

voltage

through

plate

contractor

KZ

by

pressing

plate

start

switch

below

the

multimeter.

This

connects

primary

voltage

to

the

main

plate

transformer

and

suction

fans.

With

proper

tune-up,

the

transmitter

would

now

be

operating

if

door

interlock

switch

S4

is

closed.

BIAS

POWER

SUPPLY

is

for

the

modulator

tubes

and

operates

in

conjunction

with

the

cathode

follower

driver

amplifier.

It

develops

280

volts

to

oppose

the

z

10

volts

developed

in

the

cathode

follower

circuit

to

provide

about

60/70

volts

to

the

grids

of

the

modu-

lator

tubes.

Z3.

INTERMEDIATE

POWER

SUPPLY

is

for

all

inter-

mediate

audio

and

RF

stages

for

plate

voltage.

Voltage

to

the

oscillator

unit

is

dropped

to

195

volts

by

resistor

R9.

Primary

of

plate

trans

-

former

TZ

is

fused

(F4)

at

3

amperes.

Filament

transformer

TS

(866A

tubes)

energizes

with

fila-

ment

start

switch

but

plate

voltage

is

delayed

about

30

seconds

by

time

delay

relay

KZ.

Door

interlocks

must

be

closed.

24.

HIGH

VOLTAGE

SUPPLY

develops

2500

volts

direct

current

for

all

833A

tubes.

All

components

are

in

the

bottom

of

the

transmitter,

including

plate

trans

-

former

Tl,

rectifier

filament

transformer

T4,

swing-

ing

choke

coil

L

1,

filter

capacitor

CZ

and

the

pair

of

_

8008

rectifier

tubes.

Rectifier

filaments

energize

by

inserting

the

"Filament

Start

Switch".

High

voltage

is

applied

by

pushing

the

"Plate

Start

Switch"

after

allowing

time

for

time

delay

relay

K4

to

operate.

Door

interlocks

must

be

closed.

ZS.

REMOTE

CONTROL

...

Separate

pages

are

included

in

this

instruction

book

entitled,

"Attachment

Of

Remote

Control".

26.

27.

DUMMY

ANTENNA

...

This

inbuilt

feature

will

be

especially

appreciated

during

the

first

tune-up

but

as

years

go

by

it

will

be

found

indisp~~sable.

Knife

blade

switch

S3

is

in

the

lower

position

to

connect

the

dummy

antenna.

A

lamp

on

the

dummy

antenna

chassis

will

flash

when

the

transmitter

is

connected

to

the

dummy

antenna.

This

is

a

warn-

ing

light

to

make

sure

the

operator

returns

switch

S 3

to

the

upper

position

to

connect

to

the

regular

antenna

when

finished

with

the

dummy

antenna.

READYING

CHECK

LIST

••

We

are

near

ready

for

tune-up.

First,

let's

recheck

as

follows:

'I

(~)

(b)

Be

sure

all

packing

material

is

removed

such

as

braces,

tie

cords

and

blocks

for

relays,

etc.

This

has

been

covered

in

"Getting

Ready".

DO

NOT

place

the

plate

caps

on

either

the

866A

or

8008

rectifier

tubes.

This

will

be

done

later.

Drawing

A30603

gives

tube

''V"

numbers

such

as

V 1,

VZ,

etc.

These

"V

"

numbers

are

stenciled

near

each

tube

socket.

(c)

The

230

volt

primary

is

connected

to

fuse

block

XF

1.

Entrance

of

this

cable

is

best

at

the

right

rear

bottom.

(d)

Audio

input

(be

sure

to

use

shielded

wire)

is

connected

to

29

and

30

on

terminal

strip

TB

1.

You

will

wish

to

ground

your

cable

shield

to

terminal

ZS.

Entrance

is

best

at

the

right,

front,

bottom.

I

Modulation

monitor

connects-

to

terminals

1

and

Z

on

terminal

strip

TBZ.

Use

solid

dielectric

coaxial

cable

for

this,

such

as

RG

-6ZU.

This

connection

is

near

the

top

at

th-e

left

front

sid-e.

(£)

(g)

Frequency

monitor

connects

to

terminals

7,,7

and

ZS

on

terminal

strip

TB

1

(location

in

(d)

above).

Use

solid

dielectric

coaxial

cable,

such

as

RG-6ZU.

Terminal

ZS

is

a

ground

connection

for

the

cable

shield.

A

big

ground

stud

will

be

found

on

the

cabinet

frame

near

the

location

of

modu-

lation

transformer

T

3.

Connect

the

Z"

copper

strap

that

goes

to

your

ground

radials,

to

this

ground

stud.

This

strap

may

enter

the

cabinet

through

the

access

hole

in

the

right

rear

where

the

230

volt

primary

cable

enters.

(h)

Connect

the

RF

output

to

the

ceramic

feed

through

insulator

near

output

load-

ing

coil

L

14.

You

may

run

your

coaxial

line

either

through

the

top

entrance

hole

or

the

base

of

the

transmitter.

This

is

a

heavy

line

and

be

sure

it

is

well

secured

and,

of

course,

the

shield

portion

of

the

cable

grounded

to

the

transmitter

ground.

(i)

Grounding

is

of

major

importance.

Remem-

ber

it

is

part

of

your

radiating

system

but

lack

of

complete

grounding

will

often

per

-

mit

stray

radio

frequency

current

to

make

its

way

into

audio

equipment,

hindering

neutralization

of

the

transmitter,

etc.

It

is

wise

to

bond

all

electrical

conduit,

metal

frame

work

of

building,

water

piping,

etc.,

to

the

overall

ground

system.

If

these

suggestions

are

followed,

there

will

be

less

trouble

over

the

years

as

the

ground

system

ages.

(j)

Be

sure

the

components

shipped

separately,

such

as

tubes,

crystals

and

time

delay

relays,

are

carefully

inspected

and

then

inserted

in

their

proper

location.

(k)

You

will

tune

up

on

the

dummy

antenna,

so

the

dummy

switch

will

be

inserted

in

the

lower

two

clips.

When

inserted,

a

micro-

switch

(SZ)

will

close,

starting

the

flashing

lamp,

if

the

filaments

are

on.

TUNE-UP

PROCEDURE

EXTREME

CAUTION

.•

Lethal

voltages

are

applied

to

·

certain

areas

of

the

transmitter.

DO

NOT

strap

out

door

interlocks.

We

suggest

two

people

present

during

initial

tune-up

so

one

may

observe

the

other's

actions,

with

the

eye

on

safety.

Using

normal

care

and

good

intelligence,

operation

around

high

voltage

can

be

completely

safe.

CARELESSNESS

CAN

MEAN

DEATH

.

For

tune-up

we

will

use

1400

Kc

as

an

example.

Con-

sult

frequency

charts

in

this

book

for

other

frequen

,

cies.

Tune-up

at

any

frequency

is

similar.

Step

by

step,

let's

now

proceed.

Be

sure

all

voltages

are

off

by

turning

off

both

filament

and

plate

start

switches.

Look

at

the

833A

tubes

as

a

safety

measure

to

be

sure

they

are

not

lighted.

Put

plate

caps

on

866A

rectifiers.

GATES

RADIO

COMPANY

-

Quincy,

Illinois,

U.S.A.

•

www.SteamPoweredRadio.Com

•

Push

filament

start

switch.

Tubes

will

light

and

time

delay

relays

start

in

action

to

close

about

30

seconds

later.

Set

multimeter

switch

to

"Plate

Cur.

Osc./Buf."

This

reads

the

combined

plate

current

of

the

untuned

oscillator

and

first

buffer

or

intermediate

amplifier.

The

first

intermediate

or

buffer

amplifier

is

tuned

by

a

slug

tuned

coil

(L3),

Drawing

M5422.

This

is

usually

factory

tuned.

Tuning

is

correct

if

by

setting

J?Ultimeter

switch

at

"RF

Driver

Grid"

a

reading

of

0.3

MA

to

0.5

MA

is

obtained.

If

not,

adjust

L3

and

capacitor

C9

until

a

reading

,

as

above,

is

obtained.

Refer

to

tuning

chart

30604

in

this

book.

Set

multimeter

switch

to

"RF

Driver

Cath."

Tune

control

C7

located

on

front

of

trans

-

mitter

by

opening

door

(see

front

view

illustration)

until

minimum

current

is

obtained.

This

will

vary

between

150

MA

and

200

MA,

depending

on

frequency.

In

this

instance

for

1400

Kc,

no

driver

tank

padding

capacitor

is

used.

Be

sure

and

consult

chart

30604

and

add

the

padding

capacitor

C

15,

if

called

for

on

your

frequency.

This

is

located

on

the

RF

driver

unit

on

the

main

vertical

aluminum

panel

and

shelf

assembly.

Set

multimeter

switch

to

"P.A

.

Grid".

If

tuning

is

proper

to

this

point,

the

meter

should

indicate

between

120

MA

and

160

MA.

This

will

vary

as

to

frequency

and

will

also

drop

slightly

when

you

apply

plate

voltage

to

the

power

amplifier

later

.

Set

multimeter

switch

to

"Input

Audio".

Reading

should

be

5

MA

to

10

MA.

Using

a

v<?ltmeter,

check

the

modulator

bias

supply

to

be

sure

it

is

functioning.

Remove

the

right

side

of

the

cabinet.

Terminal

lug

#

11

will

measure

about

-280

volts

against

ground.

Use

Drawing

C77711

or

C78180,

if

need

be.

The

280

volts

will

vary

slightly

with

line

voltage

and

this

is

normal.

Re

-

place

the

side

removed,

immediately.

Turn

each

modulator

bias

control,

R 1

and

R2

controlled

from

the

front

(door

open),

entirely

counter-clockwise

or

to

"Max."

position.

This

will

provide

80

volts

of

bias

to

the

modulators

for

minimum

current

while

we

are

tuning

up

the

radio

frequency

section

.

We

will

come

back

to

this

final

adjustment

later.

Shut

down

the

transmitter

entirely

by

pressing

filament

stop

switch

S6

on

the

front

of

the

transmitter.

Refer

to

tuning

chart

30604.

Check

the

"active

turns"

listed

for:

(a)

the

P.A.

tank

coil

L

12,

(b)

for

loading

coil

L 13,

and

(c)

for

output

coil

L 14.

For

your

fre-

quency,

_

adjust

each

coil,

either

variable

or

fixed,

to

what

is

indicated

on

the

chart.

Again

these

turns

will

vary

slightly

under

local

in-

stallation

conditions.

In

our

1400

Kc

tune

-up

example,

we

have:

15.7

active

turns

for

P.A.

tank

coil

L 12

10

active

turns

for

loading

coil

L 13

7

active

turns

for

output

coil

L 14

Again

by

consulting

Drawing

30604

we

find

the

proper

size

capacitor

for

your

frequency.

Using

1400

Kc

as

our

example,

we

find:

P.A.

tank

pa

dder

ca

pa ci

tor

C 11

and

C 12 - 2

Type

G2

.00025

mfd.

Input

loading

capacitor

C 13 -

,003

mfd.

Output

loading

capacitor

C 14 -

.003

mfd.

NEUTRALIZING

...

Attention

to

this

procedure

is

very

important

as

complete

neutralization

is

man-

datory

for

good

performance.

Neutralizing

means

eliminating

any

RF

voltage

from

the

tank

circuit

of

the

power

amplifier

with

all

RF

stages

operating

except

the

power

amplifier

stage.

BE

POSITIVE

the

high

voltage

IS

OFF

.

As

yet

you

should

not

have

the

plate

caps

on

the

8008

rectifiers.

Keep

them

off.

To

be

sure,

press

the

hi

gh

voltage

plate

start

switch

to

Off

position.

A

grid

dip

meter

, a

wave

meter

with

some

sort

of

indicator

or

a

flashlight

lamp

connected

to

a

few

turns

of

insulated

wire

will

do

as

a

neutralization

indicator

.

Of

course,

a

very

good

neutralization

indicator

is

already

built

in

the

transmitter;

namely,

the

Power

Amplifier

Grid

Current

Meter.

Two

methods

of

neutralization

will

be

described;

first,

that

of

using

th

·e

grid

current

for

neutralization

indication.

1.

Keep

the

dummy

load

connected

to

the

power

amplifier

.

2.

Energiz

e

all

filaments

by

depressing

the

Fil.

Start

Switch.

After

approxi

-

mately

30

seconds

,

the

oscillator,

1st

IPA

and

2nd

IPA

are

in

operating

con-

dition

and

grid

current

will

be

flowing

in

the

Power

Amplifier.

(

The

multi-

meter

switch

is

set

on

"P.A.

Grid

Cur."

position)

.

3.

Set

the

neutralizing

condenser

C 10

at

maximum

capac

i

ty,

plates

fully

meshed.

This

control

is

conveniently

located

on

the

top

front

P.A.

panel

near

the

right

-

hand

lower

corner.

4.

Adjust

the

P .

A.

tank

coil

L 12

tuning

by

means

of

the

right

-hand

knob

on

the

P.A.

panel

(marked

"P.A.

Tune")

when

resonance

is

reached,

the

grid

curren

t

as

in

dicated

on

the

multimeter

will

dip

noticeably

(if

not

neutralized)

5.

Change

the

neutralizing

condenser

setting

by

a

small

amount

(gradually

decreasing

capacity),

then

re-resonate

the

power

amplifier

(Point

4

above),

noting

the

dip

in

the

grid

current.

As

the

correct

neu-

trali

z

ing

is

reached,

the

grid

current

dip

will

become

less

and

less

until

complete

neutralization

is

effected.

This

will

be

indicated

by

no

deflection

of

the

power

amplifier

grid

current

meter

when

resonance

is

obtained.

Under

these

conditions

the

amplifier

should

be

neu-

tralized.

In

case

complete

neutralization

cannot

be

obtained,

sev

_

eral

taps

on

driver

tank

coil

LS

(Drawing

M5393)

are

provided

to

aid

this.

Using

the

exact

center

tap,

move

the

grid

lead

over

one

tap

and

repeat

the

entire

neutralization

procedure

as

above.

The

correct

tap

will

always

be

found

for

entire

neutralization.

-

In

many

instances

your

transmitter

is

tuned

at

the

factory

to

your

frequency.

In

thls

case,

you

will

find

neutralization

is

largely

a

touch-up

pro-

cedure.

·

GATES

RADIO

COMPANY

-

Quincy,

Illin~is,

U.S.A.

Page

5

www.SteamPoweredRadio.Com

NEUTRALIZING

WITH

A

FLASHLIGHT

BULB

The

same

procedure

will

apply

as

previously

men-

tioned

to

provide

Power

Amplifier

grid

current.

A

flashlamp

bulb

is

a

sensitive

and

inexpensive

RF

indicator.

The

bulb

should

be

connected

in

series

with

a

couple

of

turns

of

insulated

wire,

approxi

-

mately

the

same

diameter

or

a

little

smaller,

than

the

PA

tank

coil

L 12.

Place

this

coil

·

and

lamp

RF

indicator

in

close

inductive

relation

with

LZ.

1.

Set

the

neutralization

condenser

at

maximum

capacity.

2.

Very

carefully

tune

the

power

ampli-

fier

toward

the

resonance

point,

It

is

important

to

tune

slowly

because

if

the

resonance

point

is

obtained

quickly,

there

most

likely

will

be

sufficient

RF

in

the

Power

Amplifier

tank

to

burn

out

the

flashlamp

bulb.

3.

Adjust

the

coupling

between

the

lamp

coil

and

L 12

so

that

the

lamp

will

glow

brightly

when

resonance

is

reached.

Now

decrease

the

neutralizing

con-

denser

capacity

a

bit,

the

lamp

bril-

liance

will

decrease,

adjust

the

power

amplifier

tuning

again

for

resonance

which

may

cause

the

lamp

to

brighten

up

a

bit.

Continue

this

operation

until

the

lamp

goes

out.

The

amplifier

will

be

satisfactorily

neutralized

under

this

condition.

4.

Remove

the

lamp

and

coil

RF

indicator

from

the

transmitter.

Remember,

all

of

these

neutralizing

.

procedures

are

done

with

the

high

voltage

removed

from

the

power

amplifier.

As

yet

we

have

not

connected

the

8008

plate

leads

to

the

tubes.

TUNING

THE

POWER

AMPLIFIER

We

are

ready,

after

neutralizing

is

complete

and

satisfactory,

to

tune

the

power

amplifier.

This

is

the

big

amplifier

that

puts

out

the

power,

so

we

go

about

it

carefully

and

methodically.

Your

overload

relays

should

protect

the

equipment

if

you

do

anything

wrong

but

here

we

are

dealing

with

power

size,

so

watch

the

power

amplifier

plate

current

meter

and

if

readings

get

too

high

(above

700

MA),

check

your

overload

relays

to

see

why

they

are

not

operating.

(See

Power

Amplifier

Protection

on

a

preceding

page.)

--

The

833A

tubes

may

have

a

cherry

red

glow

.

in

the

center

of

their

plates.

This

is

normal

but

a

deep

red

spread

all

over

the

platt.

of

the

tube

usually

indicates

excessive

current

and

will

be

indicated

on

the

plate

current

meter.

---

Turn

off

all

primary

voltage

by

pressing

the

"Filament

St

efl

"

switch.

We

have

earlier

set

all

tank

and

loading

coils

to

the

proper

"active

turns"

and

capacitors

in

accordance

with

your

frequency.

--

Remove

the

front

door

screen.

Again

be

sure

all

voltage

is

off.

Press

the

filament

stop

switch

again

to

be

sure.

Place

only

one

plate

cap

on

an

8008

tube.

Leave

the

other

one

off.

This

will

provide

partial

plate

voltage

that

will

vary

with

load

but

as

a

guide,

approximately

900

volts

when

200

MA

is

drawn

by

the

power

amplifier.

Now

replace

the

perforated

screen.

-

Turn

on

transmitter

by

pressing

the

fila-

ment

start

switch.

Leave

time

for

the

time

delay

relays

to

operate.

Check

to

be

sure

you

have

in

excess

of

100

MA

grid

current

to

the

power

amplifier.

We

are

ready

for

our

first

try

of

the

power

amplifier.

Press

the

"Plate

Start"

switch.

--

Immediately

adjust

the

"Power

Amplifier

Tune"

control

for

lowest

plate

current

read-

ing

on

the

"P.A.

Plate"

meter.

Keeping

this

control

in

one

hand,

adjust

the

"P.A.

Loading"

control.

If

current

goes

up,

readjust

"Power

Amplifier

Tune''

for

lowest

current.

When

you

reach

about

ZOO

MA

at

900

plate

volts,

you

are

near

normal,

175

MA

at

around

950

or

1000

volts

is

near

normal,

but

much

above

200

MA

would

indicate

improper

tuning

or

loading.

When

tuned,

you

will

be

indicating

a

small

amount

of

RF

current

in

the

"Line

Current"

meter

between

the

two

controls

you

have

been

tuning.

--

If

above

is

norm

·

al,

you

are

ready

for

total

high

voltage.

Shut

down

the

transmitter

by

pressing

the

"Filament

Switch"

to

off.

Remove

the

front

door

perforated

screen,

and

observe

that

tubes

are

off

--

just

to

be

sure.

Now

attach

the

plate

cap

to

the

other

8008

rectifier.

Replace

the

perforated

door

screen.

Make

sure

it

is

locked

in

place

to

engage

interlock

switches

S3

and

S4.

-

You

are

ready

to

try

full

power.

Press

the

"Filament

Start"

switch

and

wait

for

the

time

delay

relays

to

operate.

Are

you

brave?

Push

the

"Plate

Start"

switch.

If

you

are

living

right,

the

power

amplifier

plate

current

will

rise

to

between

500

and

600

MA

and

you

will

have

between

2500

and

2550

plate

volts.

Your

"Line

Current"

meter

will

read

around

4

amperes.

Rotate

your

''

Power

Amplifier

Tune''

control

slightly

to

see

if

you

can

raise

the

line

curt-ent.

Even

one-tenth

of

an

ampere

is

important.

Re-

adjust_

your

"P.A.

Loading"

control,

watching

your

hne

current.

--

You

have

arrived

if

you

approximate

these

readings.

...

plate

current,

500

to

550

MA

...

plate

voltage,

2500

to

2550

volts

...

line

current

(into

50

ohm

dummy),

4.45

amperes

-

With

inductive

tuning,

maximum

power

out-

put

does

not

always

occur

at

minimum

power

amplifier

plate

current.

Usually

one

side

of

tank

resonance

provides

greater

output

than

the

other

side.

Resonance

is

always

lowest

plate

current

by

adjusting

"Power

Amplifier

Tune".

Check

your

suction

fans

for

operation.

The

modulator

tubes

are

probably

reading

little

or

no

current

on

the

modulator

plate

meter.

--

The

efficiency

of

the

power

amplifier

should

be

around

70%-.

Read

Par.

3

of

"How

Can

We

Help

You?

"

in

the

back

of

this

book

on

com-

·

puting

efficiency.

ADJUSTING

THE

MODULATORS

...

Earlier

we

have

moved

the

modulator

bias

controls

entirely

counter-clockwise,

or

to

"Max."

position.

This

gave

us

maximum

bias

or

too

much.

Now

we

want

to

adjust

properly.

What

we

want

is

80

MA

for

both

tubes,

or

40

MA

for

each

tube.

This

is

easy.

Be

sure

no

audio

signal

is

being

sent

to

Page

6

GATES

RADIO

COMPANY

--

Quincy,

Illinois,

U.S.A.

www.SteamPoweredRadio.Com

the

transmitter.

If

your

limiter

is

already

con-

nected,

close

both

controls

on

the

limiter.

--

Now

place

the

modulator

selector

switch

located

just

below

the

modulator

bias

controls

to

position

"Mod.

l"

and

adjust

the

left

modulator

bias

con-

trol

until

the

modulator

plate

meter

reads

40

MA.

Now

place

this

switch

to

"Mod.

Z"

position

and

adjust

the

right

bias

control

to

40

MA

..

By

moving

this

switch

to

"Total"

a

reading

of

80

MA

on

both

tubes

is

indicated.

This

will

be

your

operating

position

of

this

switch

for

broadcasting.

This

feature

allows

you

to

check

modulator

tubes

for

balance

and

re

-balance

them

from

time

to

time

as

all

tubes

do

not

age

alike.

Slight

touch-up

of

these

controls

often

helps

in

final

distortion

readings.

Actually

perfect

balance

of

static

currents

is

not

mandatory.

In

some

cases

one

tube

drawing

slightly

more

static

current

than

the

others

provides

the

best

measurements.

They

should

not

be

out

of

balance

severely,

however.

-

THE

PLATE

RHEOSTAT

marked

"Plate"

on

the

inside

cabinet

support,

provides

about

ZOO

plate

volt

variation

for

day

to

day

power

adjustments.

Clockwise

rotation

increases

plate

voltage.

-

THE

FILAMENT

RHEOSTAT

located

adjacent

to

the

plate

rheostat

adjusts

correct

primary

voltage

to

all

filament

transformers

and

the

bias

power

supply.

Adjust

this

so

the

"Fila-

ment

Voltmeter''

always

reads

10

volts

and

all

other

filament

and

bias

voltages

will

be

correct.

--

YOUR

ANTENNA

COUPLING

EQUIPMENT,

not

involved

in

these

instructions,

is

a

very

important

part

of

the

entire

successful

oper

-

ation.

The

instruction

book

with

the

antenna

coupler,

aids

in

its

alignment.

As

all

towers

must

be

measured

by

an

approved

engineer,

this

engineer

could

use

his

radio

frequency

bridge

for

proper

tune

-up

of

the

antenna

coupler.

Ask

him

about

it.

If

your

opera-

tion

is

directional,

the

engineer

will,

of

course,

tune

the

entire

directional

system

including

the

tower

coupling

equipment.

HELPFUL

OPERATION

PROCEDURE

THE

CRYSTALS

are

of

the

vacuum

enclosed

type.

There

are

no

air

g~ps

and

~~

only

0

~djustmE;1;ts

are

those

marked

Freq.

1

an~

freq'.

Z

which

are

small

trimmer

cotitiensers

to

zero

in

each

crystal.

These

controls

will

allow

about

a

/.

30

cycle

change

at

1600

Kc

and

about

t_

10

cycle

change

at

540

Kc.

-

During

equipment

tests

your

external

frequency

measuring

source

will

advise

you

of

your

frequency.

You

can

then

zero

in

by

adjusting

the

trimmer

condensers

and

then

adjust

your

frequency

monitor

to

correspond.

As

the

frequency

monitor

has

greater

accuracy

than

the

transmitter

crystals,

future

"zeroing

in"

of

the

transmitter

crystals

is

referred

to

the

frequency

monit6r.

CLEANLINESS

cannot

be

over-emphasized.

Please

read

Par.

30,

31

and

3Z

of

"How

Can

We

Help

You?

"

in

the

back

of

this

book.

Dirt,

grime,

dust

and

maintenance

negligence

cause

more

outages

than

any

other

cause.

Outside

cleaning

indicates

pride

of

ownership.

Inside

cleaning

will

prevent

the

engineer

from

being

called

away

from

an

afternoon's

fishing

jaunt,

later

on

--

and

most

important,

advertising

revenues

will

not

be

lost.

AIR

FILTERS

must

be

replaced

regularly.

If

not,

the

hot

air

will

not

be

removed

from

the

transmitter

and

heat

is

cleanliness

as

an

offender

and

trouble

maker.

We

have

made

it

easy

to

replace

them.

Open

the

front

door,

slip

up

and

out,

replace

--

don't

even

turn

off

the

transmitter.

RELAY

MAINTENANCE

is

usually

well

under-

stood

as

to

procedure

and

necessity.

Dirt

and

grime

will

eventually

have

a

binding

action

on

the

armatures.

Check

contacts

for

pitting.

Burnish

as

need

be.

A

burnishing

tool

is

preferred.

If

not

available,

use

a

very

light

grade

of

sandpaper

sparingly.

AIR

FANS

keep

the

blades

clean.

They

run

faster

and

work

better

to

remove

more

air.

They

require

no

lubrication.

PRINTED

WIRING

is

the

new

Gates

solid

process.

To

further

protect

it,

all

printed

wiring

boards

are

treated

with

silicone

varnish.

Use

a

soft,

brittle

brush

to

re

-

move

dust

-

nothing

else.

METERS

...

The

five

meters

on

the

vertical

column

can

be

replaced,

if

ever

need

be,

by

removing

the

entire

vertical

decorative

front

grill

to

expose

all

meters

and

the

start-stop

switches.

ASK

YOUR

MANAGER

to

provide

you

with

a

suction

type

vacuum

cleaner.

The

kind

you

clean

a

davenport

with.

This

will

make

suck-

ing

out

dust

from

the

inside

both

easy

and

pleasurable.

It

is

not

an

investment

as

it

will

save

him

in

repair

parts

in

years

to

come.

TEST

EQUIPMENT

...

A

broadcasting

station

must

own

minimum

test

equipment.

A

volt-

ohmmeter

and

an

oscilloscope

are

·

very

desir-

able

and

not

.

excessive

in

cost.

Annually,

all

broadcasters

must

talce

proof

of

performance

measurements.

Annual

tests

are

the

minimum.

For

top-flight

performance

to

assure

the

mar-

velous

Hi-Fi

signal

capable

of

this

equipment,

monthly

performance

tests

are

recommended.

The

Gates

SA-131

proof

of

performance

set

is

recommended

to

keep

a

fine

broadcasting

station

continually

excellent.

SUMMARY

You

have

the

finest

transmitter

money

can

buy.

We

at

Gates

cannot

always

know

of

the

accessories

being

us-ed.

It

goe

..

without

saying

that

a

poor

microphone

will

insure

poor

transmission

quality,

no

matter

how

good

the

transmitter.

Much

enters

into

the

final

results

-

the

quality

of

the

telephone

line

between

studio

and

transmitter,

your

turntables,

control

console

and

even

people.

-

It

is

better

to

have

less

eq_uipment,

all

good.

It

is

well

to

remember

that

your

transmitter

will

indicate

all

performance,

good

and

bad.

A

loose

or

broken

connection

in

the

transmission

line

will

in-

dicate

at

the

transmitter.

A

poor

connection

at

the

tower

will

indicate

at

the

transmitter.

All

problems

are

reflected

on

the

transmitter.

Only

your

trans-

mitter

yells

''ouch''.

So

if

you

have

a

problem,

remember

you

have

more

than

a

transmitter

you

have

a

system.

Gates

engineers

will

be

delighted

to

correspond

or

confer

by

telephone

about

any

questions

you

might

have.

Do

not

hesitate

to

let

us

help

you.

-

We

thank

you

for

your

business

and

the

confidence

placed

in

us

..

GATES

RADIO

COMPANY

-

Quincy,

Illinois,

U.S.A.

Page

7

www.SteamPoweredRadio.Com

ATTACHMENT

OF

REMOTE

CONTROL

IN

GATES

TRANSMITTERS

BC-lT,

BC-500T,

BC-250T

Refer

to

the

following

overall

transmitter

schematic

diagrams:

BC

-lT

.......

C-78180

BC

-500T

....

E-25569

BC

-250T

....

E

-25582

A

steel

plate,

drilled

for

mounting

the

M4719

plate

voltage

kit,

M4720

plate

cur-

rent

kit

and

M4703

rheost

.

at

assembly

is

availab

le

for

the

installer's

use.

Tapped

mounting

holes

for

this

plate

have

been

provided

in

the

cabinet

corner

supports,

directly

beneath

the

terminal

boards

and

contactors

(

ri

ght

side

of

transmitter

as

viewed

from

front).

Photographs

showing

the

remote

control

kits

in

place

are

in-

cluded

with

these

instructions.

M4703

MOTOR

RH

EOSTAT

ASSEMBLY

As

viewed

from

the

rheostat

end

of

this

a

ssembly,

with

the

three

rheostat

terminals

to

the

left,

strap

the

center

terminal

(arm)

to

the

top

terminal.

Since

application

of

"increase"

voltage

brin

6s

about

clockwise

rotation

of

the

arm

(same

view),

resistance

will

decrease.

With

application

of

"decrease"

voltage,

the

resistance

will

increase.

The

existing

plate

voltage

meters

in

the

BC

-lT,

BC

-500T

and

BC

-250T

transmitters

read

plate

to

cathode

voltage,

whereas,

the

remote

control

voltage

sampling

kit

will

read

plate

to

ground

voltage.

Therefore,

in

order

for

the

two

meters

to

track

the

rheostat

must

be

wired

in

series

with

the

high

voltage

lead

feeding

the

final

amplifier

.

The

control

circuit

hook-up

between

the

M4

703

motor

and

remote

control

unit

is

explained

in

the

Remote

Control

instruction

book.

PLATE

VOLTAGE

EXTENSION

KIT,

M4719

1.

Using

Packard

cable

or

a

high

voltage

equiv-

alent,

connect

the

M4

7 19

"HV"

terminal

to

the

motor

rheostat

terminal

furthermost

from

the

power

supply

.

Do

not

connect

to

the

rhea

-

stat

terminal

which

goes

to

the

modulation

reactor.

Connect

the

M4

7 19

1.<;it

terminal

''

G

''

to

a

good

ground

point

within

the

transmitter.

2.

Refer

to

the

Remote

Control

instruction

book

for

connection

of

meter

sample

voltage

to

remote

control

unit

.

PLATE

CURRENT

EXTENSION

KIT,

M4720

1.

The

plate

current

kit

is

to

be

connected

between

the

lower

end

of

P .

A.

overload

relay

K6

and

ground.

2.

A

ground

lead

runs

from

a

chassis

ground

terminal

to

one

of

the

coil

terminals

on

K7

modulator

overload

relay,

thence

to

one

coil

terminal

of

K6

P.A

.

overload

relay.

Clip

out

the

portion

between

K6

and

K7.

K7

is

to

retain

its

direct

chassis

ground

since

we

want

only

P.A.

current

to

flow

through

the

plate

current

kit.

3.

Both

K6

and

K7

must

retain

their

shunt

resistors

directly

across

their

respective

coils.

4.

The

"G"

terminal

of

the

two-terminal

strip

on

kit

M4720

connects

to

a

good

ground

point

within

the

transmitter.

Run

a

lead

from

the

other

terminal,

upward

to

the

K6

terminal

which

was

formerly

grounded.

5.

Refer

to

the

Remote

Control

instruction

book

for

connection

of

sampling

voltage

to

remote

control

unit.

REMOTE

PLATE

START-STOP

CIRCUITRY

The

BC-lT,

BC-500T

and

BC

-250T

overall

schematic

diagrams

plainly

indicate

the

necessary

connections

for

filament

and

plate

remote

control.

The

plate

start-stop

circuitry

consists

merely

of

shunting

the

transmitter

plate-start

switch

with

a

set

of

normally

open

remote

control

contacts.

The

plate

-stop

function

is

accomplished

by

connecting

a

set

of

normally

closed

remote

contacts

in

series

with

the

transmitter

plate

-

stop

switch

.

REMOTE

FILAMENT

START-STOP

CIRCUITRY

Note

that

a

jumper

is

to

be

removed

in

the

filament

contactor

circuit.

Removal

of

this

jumper

disables

the

'holding

contacts

on

the

filament

contactor.

A

se

t

of

remot

e

normally-open

contacts

shunted

across

the

transmitter's

filament-start

switch

will

then

serve

as

filament

start

and

hold,

satisfying

FCC

require-

ments

for

a

"fail-safe"

circuit

.

If

the

telephone

line

between

studio

and

transmitter

fails,

or

if

the

remote

control

equipment

becomes

defective

the

remote

holding

contacts

open.

This,

in

turn,

causes

the

filament

contactor

to

drop

out,

removing

the

transmitter

from

the

air.

In

multiple

transmitter

installations,

the

filament

fail-

safe

operation

is

accomplished

in

a

slightly

different

manner,

so

that

individual

filament

control

for

the

various

transmitters

is

possible.

Each

transmitter

employs

its

individual

slave

relay

associated

with

its

respective

transmitter

filament

contactor.

The

fail-

safe

relay

in

the

remote

control

unit,

in

turn,

holds

energized

all

of

the

slave

relays.

The

slave

relay

c.

ontacts

are

wired

in

series

with

their

respective

fi.lam~nt

contactor

off

circuits,

providing

a

holding

c1rcu1t.

Thus,

separate

on-off

filament

control

is

p~ssible

f?r

each

transmitter.

These

circuits,

along

with

drawings

are

presented

in

detail

in

the

Remote

Control

instruction

book.

Page

8

GATES

RADIO

COMPANY

--Quincy,

Illinois,

U.S

.

A.

•

www.SteamPoweredRadio.Com

•

TYPICAL

VOLTAGE

CHART

GATES

BC-lT

lKW

AM

TRANSMITTER

These

measurements

made

with

a

Simpson

#

260

Volt-Ohmmeter,

a

20,000

ohms

per

volt

DC

and

1000

ohms

per

volt

AC

instrument.

DC

Voltages

to

GROUND.

First

Audio

Input

(V

1,

V2,

6BG6G's)

Plate

Volts

Screen

Volts

Filament

Volts

Cathode

Volts

275

DC

200

DC

6.3

AC

49

DC

Cathode

Follower

(V3,

V4,

6BG6G

's)

Plate

Volts

Screen

Volts

Ca

th

ode

Volts

Neg.

Filament

Volts

650

DC

230

DC

70

DC

6.3

AC

Modulators

(VB,

V9,

833A's)

Plate

Volts

Plate

Current,

Static

Bias

Volts

Filament

Volts

2600

DC

40

MA

each

Approx.

65/70

DC

10

AC

Crystal

Oscillator

(V 1,

12BY7A)

Plate

Volts

Screen

Volts

Ca

th

ode

Volts

Filament

Volts

100

DC

50

DC

.8

DC

6.3

AC

First

IPA

(V2,

12BY7A,

A

part

of

Osc.)

Plate

Volts

Screen

Volts

Cathode

Volts

Filament

Volts

205

DC

105

DC

3.5

DC

6.3

AC

Second

IPA

(V

1,

V2

Parallel

6BG6G

's)

Plate

Volts

Screen

Volts

Ca

th

ode

Volts

Filament

Volts

650

DC

400

DC

45

DC

6.3

AC

Power

Amplifier

(V6,

V7,

833A's)

Plate

Volts

Plate

Current

Bias

Volts

Filament

Volts

Bias

Supply

2500

DC

500

/

550

MA

DC

360

DC

10

AC

Output

of

Supply,

measured

at

terminal

# 11

of

Audio

Printed

Board

-

Neg.

280V

.

Intermediate

Plate

Supply

Output

of

Supply,

measured

at

L5

,

terminal

#2 -

600

/

650V

DC.

High

Voltage

Plat

e

Supply

Output

of

Supply

,

measured

at

top

end

of

Bleeder

,

Rl0,

2600V

DC.

NOTE

:

Voltages

and

currents

are

approxi-

mate

and

will

vary

slightly

with

line

voltage

and

other

local

conditions.

IF

THEY

ARE

NEEDED

Listed

below

are

several

items

mentioned

in

this

instruction

book.

In

case

you

need

any

of

them,

they

are

listed

below

with

prices.

RG

/

62U

coaxial

cable

for

connecting

frequency

and

/

or

modulation

monitors

to

transmitter

.•............•.............

per

ft.

.

06¢

2"

copper

strap

for

grounding

trans

-

mitter

to

tower

radials

.............•..

per

ft.

.23¢

Removable

air

filters,

2

required

per

transmitter,

order

catalog

M5825

...

each

.

95¢

Burnishing

tool

for

cleaning

relays,

Type

TM

-1

..•.....•.•..•..................•

each

.60¢

Spare

crystal

and

vacuum

holder,

please

state

your

frequency

when

ordering,

catalog

M5602

....•.

.

.......

each

$

70.00

GATES

RADIO

COMPANY

Spare

100

%

tube

complement

for

BC

-lT

transmitter,

a

tube

for

every

socket,

catalog

TK287

..

...........

.

.............•

set

$

270.35

Spare

FCC

tube

complement

for

BC-lT

transmitter,

tubes

required

by

FCC

as

spares,

catalog

TK288

.•

..

.

..

...

.

......

set

$

136.15

SA-131

proof

of

performance

equip-

ment,

listed

on

Page

149

Gates

catalog

.............•......

.

.......

.

........

each

$

513.00

NOTE

:

As

copper

prices

vary

on

the

daily

market,

copper

strap

and

coaxial

cable

may

vary

upward

or

down-

ward

from

above

stated

prices.

Terms

are

F.O.B.

Quincy,

Illinois.

Quincy,

Illinois,

U.S.A.

Page

9

www.SteamPoweredRadio.Com

BC-lT

(M5393)

PARTS

LIST

BASIC

CABINET

ASSEMBLY

Symbo

l

No

.

Drawing

No.

B 1,

B2

Cl

C2

C4

C 10

LI

L2

L3

L4

Rl0

Rl

l

Rl2

R

13

Rl4

S3,S4

T l

T2

T3

T4

Yq.,80

TS

ff,

~<\

V 1,

V2

V3,V4

XV

1,

XV2

XV3,XV4

2676-PM-101

C -

77697

-10

l

AC-10458E

AC-10465E

A-30526-101

AP-10459E

AP-30097K

AM-30469E

AF-10456K

Description

Fa

n

Assembly

Cap

.

Filter,

10

mid

.

1000

{W)

V.

Cap.

Input

Filter

, 8

mfd

.

3000(W)V.

Cap

.

Coupling,

2

mid

.

3000

V.

~

Ne

ut.

Condenser

asse~ly

•

Swinging

Choke

Modulation

Reactor

Filter

Choke

Res.

Bleed

er ,

100K

ohm,

100

W.

Resistor,

Bleeder

Precision

Meter

Multiplier,

3

megohm

, 3

KV

Control

(Fil.

Rheostat),

7½

ohm,

150

W.

Control

(Plate

Rheostat)

400

ohm

,

300

W.

Interlock

Switch

Transformer

(High

Voltage)

Transformer

(

600

V.

Power)

Transformer

(Mod.)

Transformer

(Fila.)

Transformer

(Fi

la

. )

Tube

8008

Tube

866A

Socket

(

8008

Rectifier)

Socket

(

866A

Rectifier)

BASIC

METER

AND

SWITCH

PANEL

A

l,

A2

Ml

M2

M3

M4

MS

R26

S5,

S6,

S7,S8

XA

l,

XA2

A-10534-10

l

C -

7770

5

-101

Lamp

Meter,

Fil.

V

oltmet

e r

0-15V

AC

Meter,

P.A.

Plate

Current,

0-lA,

DC

Meter,

P

.A

.

Voltmeter

0-1

MADC,

W/

0-3000V

Scale

Meter,

Modulation,

0-1

Amp.

DC

Multimeter,

0-1

MADC

W

/Q

-30,

0-300

MADC

Scale

Multimeter

Series

Res.

Assy.

Fil.

&

Plat

e

Start-Stop

Switch

Assy.

Socket

BASIC

P.A.

TUNING

AND

LOADING

ASSEMBLY

C8,C9

C

11,

C 12

C

13,

C

14

Cap

..

001

mid

.

Cap.

(Det.

by

Freq.)

Ca

p .

(Det.

by

line

i

mpedance)

Symbol

No.

Drawing

No.

L9

Ll0,

Lll

L 12

L 13

L 14

L

15

M6

A-30910-10

l

105-VB

-3735F

26-FB

-2843F

30-VB

-2344F

A-10391-102

R

15,

R

16,

R

15A,

Rl5B,

Rl6A,

Rl6B

TB2,

TB

3

Description

P.A

.

Plate

Choke

(Det.

by

Freq.)

Parasitic

Suppressor

Coil

P.A

.

Tank

Coil,

Input

Loading

Coil,

Output

Loading

Monitor

Coil

Meter,

RF

Line

Current,

0-8

RF

Amp.

Res.

(Part

of

LlO,

Lll)

Terminal

Board

BASIC

PANBL

AND

SHELF

ASSEMBLY

(R.F.

Audio,

Relay

and

Bias)

CS,

C6

C7

C 15

Cl6, Cl9,

C20

C21,

C22,

C25

C 17

C 18

C23,

C24

F

1,

F2

F3,

;F4

Kl,

K2

K3

K4

KS

K6

K7

LS,

L6

L7

LS

Pl

Rl,

R2

R3

R4,R5

R6

R7,

RS

R9

R 19,

R20

R2

l,

R22

AK-12635

A-30518-101

B

-65284-101

A-3404-6

R23,

R24,

R25

Sl

A-10900-2

S2

T6

AI-3002

T7

AP-30098K

TS

AF

-30

l00K

T9

AF-30099E

TB

1

A-30544-101

TPl

B-11729-19

Cap.

4

mid.

600V

oil

filled

Cap.

Plate

Cap.

(Det.

by

Freq.)

Cap

..

01

mfd.

1000

(W)

V.

Cap

..

002

mfd.

1200

(W)

V.

Cap.

1

mfd.

1000V.

Cap

..

01

mid.

600

(W)

V.

Fuse

30

,

Amp.,

250V

(non-

renewable)

Fuse.

3

Amp.

Fuse

3

amp.,'

Slo-Blo

Fil.

Plate

Start-Stop

Relay,

230V.

Master

O.L.

Relay,

230V,

50

/

60

Cy.

Time

Delay,

HV

Relay

Time

Delay,

600V

Relay

Overload

Relay,

6V,

DC

Modulator

Overload

Relay

Choke,

Isolation

Filter

&

Bias

2nd

IPA

Coil

Plate

Coil

Socket

Bias

Control,

l0K

ohms,

4

W.

Wirewound

Res.

5000

ohm,

l0W.

Res.

6000

ohm,

l0W

.

Res.

2500

ohm,

l0W.

Res.

5000

ohm,

SOW.

·

Res.

20,000

ohm,

25W.

Res.

7.5

ohm,

lOW.

Res.Adj.

l0ohm,l0W.

Res.

3

ohm,

lW,

5%

Mod.

Switch

Multimeter

Switch

Transformer,

Audio

Input

Transformer,

Bias

Transformer,

Multi-Fil.,

6.3V

Transformer,

Multi-Fil.,

l0V

Terminal

Board

Assembly

Tie

Point

Page

10

GATES

RA

DI

O

COMPANY

-

Quincy,

Illinois,

U.S.A.

•

www.SteamPoweredRadio.Com

a

Symbol

No.

Drawing

No.

Description

VS

Tube,

SR4GY

V6, V7,

VS,

V9

Tube,

833A

XFl

Fuse

Block

XF3,

XF4

Fuseholder

XK4,

XKS

XVS

Socket

XV6,

XV?

XV8,XV9

C-77708-101

P.A.

and

Mod.

Socket

Assy.

FEEDBACK

LADDER

ASSEMBLY

C 1,

Cl

C3,

C4,

CS,

C6,

C7,

CS,

C9,

Cl0

Rl,

R2

R3,

R4,

RS,

R6,

R7,

RS,

R9,R10

C 1,

Cl,

C3,

C4,

CS,

C6,

C7

Ll

L2,

L3

A-30S20-101

Rl

R3,R4,RS

R6,

RS

R7,

R9

R

10

Rll,Rl2

Vl,

V2

XV1,XV2

Cap

..

002

mfd.,

1200

(W)

V.

Cap

..

0001

mfd.,

1200

(W)

V

Res.

82K

ohm,

2W,

S%

Res.

2.2

megohm,

2W,

5%

Cap

..

01

Mfd.,

1000

(W)

V

Choke,

2.5

mh.

Parasitic

Suppressor

Res.,

12K

ohm,

2W,

10%

Res.,

250

ohm,

20W

Res.,

3

ohm,

lW,

5%

Res.,

47

ohm,

2W,

10%

(Used

on

L2

and

L3)

Res.

47

ohm,

2W,

10%

Res.

15K

ohm,

20W

Res.

20

ohm,

lW,

5%

Tube

6BG6G

Socket

AUDIO

INPUT

AND

DRIVER

PRINTED

CIRCUIT

ASSEMBLY

Cl,C2

C3

C4,C5

C6,

C7

cs

L

1,

L2

Rl,

R2

A-30531-101

R3

A-3404-8

R4,Rl5,Rl6

RS

R6,R7

RS,

R9

Rl0

Rll,Rl2

Rl3,Rl4

R

19,

R20

R21

R22,

R23

Rl7,

R18

Cap.

.00027

mfd.

Cap

.

.47

mfd.,

400V

Cap.

.01

mfd.,

600V

Cap

..

33

mfd.,

600V

Cap

..

01

mfd.,

1000

(W)

V

Parasitic

Suppressor

Res.,

33K

ohm,

2W,

10%

Control,

1000

ohm

Res.,

82K

ohm,

2W,

10%

Res.,

120K

ohm,

2W,

10%

Res.,

l00K

ohm,

2W,

10%

Res.,

470K

ohm,

2W,

10%

Res.,

l0K

ohm,

2W,

10%

Res.,

l0K

ohm,

l0W

Res.,

47K

ohm,

2W,

10%

Res.,

20

ohm,

lW,

5%

Res.,

8200

ohm,

2W,

10%

Res.,

47

ohm,

2W,

10%

(Part

of

Ll

and

L2)

Res.,

47

ohm,

2W,

10%

Symbol

No.

Drawing

No.

Vl,

V2

V3,

V4

XV1,XV2

XV3,XV4

lKW

DUMMY

ANTENNA

Al

Rl,

R2,

R3

R4,R5,R6

R7,

RS

Sl

S3

TB

1

XS

1

A-4938-101

Description

Tube,

6BG6G

Socket

Lamp,

60W,

230V

(Mounts

in

S 1)

Res.,

412

ohms,

190W,

non-inductive

Winker

Micro

Switch

Shorting

Blade

and

Handle

Assembly

Terminal

Board

Socket

M5422

OSCILLATOR

UNIT

FOR

AM

TRANSMITTER

C 1,

Cl

C3

C4

C5,C7,C8

C6,

Cll

C9

C

10

Jl

Ll,

L2

L3

Rl,

R6

R7

R3, R9,

Rl0,

Rll

R4

RS,

RS

Rl2

Rl3

R14

Rl

Sl

Vl,

V2

XV1,XV2

XY1,XY2

Yl,Y2

A-30316-101

Variable

Cap.,

3.9-50

mmfd.

Cap.

24

mmfd.,

500

(W)

V

Cap.

800

mmfd.,

500

(W)

V

Cap

..

01

mfd.,

600V

Cap.

100

mmfd.,

500

(W)

V

Variable

Cap.

6.7-140

mmfd

Cap.

l0p

mmfd.,

500

(W)

V

Receptacle

R.F.

Choke,

2.5

mh.

Variable

Coil,

105-200

mh.

Res.,

l00K

ohm,

2W,

10%

Res.,

150

ohm,

2W,

10%

Res.,

27K

ohm,

2W,

10%

Res.,

15Kohm,2W,

10%_

Res.,

l0K

ohm,

2W,

10%

Res.,

1000

ohm,

2W,

10%

Res.,

47K

ohm,

2W,

10%

Res.,

10

ohms,

lW,

5%

Res.,

1000

ohm,

2W,

10%

Rotary

Switch

Tube,

12BY7A

Noval

Socket

.

Crystal

Socket

Crystal

GATES

RADIO

COMPANY

-

Quincy,

Illinois,

U.S.A.

Page

11

Gates BC-1T Instruction Manual

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