Sparta 683 User manual

www.SteamPoweredRadio.Com

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MOD L

683

SCA GENERATOR

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Division

of

Cetec

Corporation

,

•

..

I

5851

Florin-Perkins Road, Sacramento,

Ca

. 95828 •

(916)

383-5353 • Telex 377-488 • Cable

SPARTA

> I -.

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www.SteamPoweredRadio.Com

I

~

ELECTRONIC

CO

RPORATION

OPERATING AND SERVICING MANUAL

MODEL

683

SCA

GENERA

TOR

Copyri

ght

SPARTA

ELECTRONIC CORPORATION , 1973

58

51

F

lorin-P

erkins

Road

,

Sacramento

,

California

TELEPHONE: (

916

)

383-5353

TELEX

377-488

CABLE

SPARTA

PRO

PRIETARY

NOTICE;

Sparta

Electronic

Corpor

ation

proprietary

dat

a

is

contain

ed

herein

.

Neither

this

document

nor

the

infor-

matio

n

contained

herein

shall

be

disclosed

to

oth

e

rs

for

manufactur-

in

g

or

any

other

purpose

except

as

authorized

in

writing

by

Sparta

Electronic

Corporation

.

Printed

in

U .S .A.

Pric

e $5 . 00

098-7070-01

October

19

73

www.SteamPoweredRadio.Com

I

Model

683 Fr

on

t

Matter

Section

I

II

III

IV

V

VI

T

ABLE

of CONTENTS

GENERAL INFORMATION

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

-

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

1-

l .

IN

TRODUCTION-----------

----

-------

---------

---

----

-

1-

2. GENERAL DESCRIPTION

-----------

-

-----

--------

----

-

--

---

1-2.

l.

Physical

Description

--

--------

-

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

---

- -

I

NSTALLATION-------

---

-----------

---

---------

------

-----

----

-

2-l.

INSTALLATION

PLANNING

------

---

---------

-

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

--

2-1.

1.

Environmental

Requirements----

----

- -

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

--

2-1

. 2. Power

Requirements--

---

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

-

---

--

2-1,

3 ,

Cooling

Requirements

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

-

2-2

.

INPUT

AND

OUTPUT

CONNECTIONS

--

- - -

--

-----

---------

-

--

OPERATION---------

.

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

3-l,

OPERATING CONTROLS

AND

I

NDICATORS--------------------

PR1NCIPLES

or

OPERATION------------

-

------

- -

-----

- -

---

-

--

-----

4-l.

INTRODUCTION---

--

-

---

-------

---

--

- -

--

----------

-

----

4-2

. GENERATOR

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

4-3

. POWER SUPPLY

------

---

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

MAINTENANCE

---------

--

- - -

-----

-

--

-

----

-----

--

- -

---------

5-l

, P

ER

I

ODIC

MAINTENANCE----

-

----

-

---------

-

------

----

-

----

5-2

.

ALIGNM

CNT

AND

ADJUSTMENT

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

-

---

5-2

. 1.

Test

Equipment-----------------

-

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

--

5-2

. 2. Alignment

Procedure

--

----

--------

-------

-

----

REPLACEABLE

PARTS--

-

---------

-

--------

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

-

------

6-

l.

ORDERING

INFORMATION

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

6-2.

PART

S

LOCATION-------------------------------------

-

--

6-3

. TABLES

or

REPLACEABLE

PARTS

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

098-7070-01

1- 1

1-1

2-1

2

-1

2-1

3

-1

3-1

4

-1

4

-1

4-1

4- 1

5-1

5- 1

5-1

6-1

(j-1

6-1

www.SteamPoweredRadio.Com

I

Mod

el

683

1-1

INTRODUCl'ION

SECTION I

GENERAL

IN

FORMAT

IO

N

Sectio

n I

Thi

s

manua

l

contains

information

required

to

install,

operate,

and

maintain

the

Sparta

Model

683

SCA

Generator

.

Section

I

describes

the

generator

and

li

s ts

its

specifications

,

Section

n

provides

in

sta

ll

atio

n

instructions

,

Section

I

ll

contains

operating

procedures

and

Section

IV

describes

the

prin

ciples

of

operation

,

Maint

enance

procedures

and

troubleshooting

diagrams

are

contained

In

Section

V

and

r

eplaceable

parts

are

identified

and

listed

in

Section

VI

.

1-2

GENERAL DESCRIPTION

Th

e

Model

683

SCA

Generator

provides

a

signa

l

meeting

the

requirements

of

a

subs

i

diary

communications

authori

za

tion

(SCA)

mode

of

operation

,

Because

of

its

design

,

this

SCA

generator

may

be

used

with

any

Direct-FM

Exciter

1'ype-Accepted

by

the

Federal

Commu

nications

Commission

for

operation

under

part

73

of

the

rules

.

If

t

he

SCA

generator

is

to

be

ope

rat

ed

at

a

frequency

of

67

KHz

simu

l

taneous

ly

with

a

standard

stereo

sign

al

make

certain

the

optiona

l S

KHz

l

ow

pass

f

il

ter

has

been

installed

.

External

muting

is

accomplished

with

a

simp

le

contact

closure

.

This

!unction

is

availab

le

al

terminals

on

th

e

rear

of

the

Unit.

As

supp

li

ed

th

e Modei

683

will

accept

program

and

tel

emetry

signals

.

Fi

ve

front

pane

l

operating

controls

are

provided

-

frequency

adjust

,

output

level,

subca

r

rier

on

-

auto

-

off,

muting

delay

und

power

on-off.

1

-2

. l PHYSICJ\L Df.SCRIPT!ON

The

Model

683

consists

of

a

single

unit

of

standard

rack

panel

construction

.

Physical

charact

e

ristic~

of

t

he

Model

683

are

listed

in

tabl

e

1-1.

Dimensions

:

Weight:

Construction

Style:

Maximum

Altitu

de

:

Maximum

Humidity

:

Connectors:

098

-

7070-01

Tabl

e

1-l

Physic

al

Charaoterlstlcs

3-

1/2"

high

, 10"

deep,

19"

wide

12

Lbs

.

1/

8"

alodin

ed

alum

inu

m w

it

h

pa

int

ed

fr

ont

panel

with

mounting

flang

es

notched

Lo

mate

with

s

tandard

1

9"

equipme

nt r

ack

To

1

2,500

feet

95%

AC-audio

input

Tel

emetry

-

Standard

barrier

strip

Output

-BNC 1'ype (

2)

1- 1

www.SteamPoweredRadio.Com

Section

I

Model

683

Table

1-2

El

ectrica

l

Characteristics

Power

Requirements:

Ambient

Temperature

Range:

Altitude

Range:

Pilot

Frequency

Stability:

Audio

Inpu

t

Impedance

:

Audio

Input

Level

:

Frequency

Response:

Di

stortion

:

Noise:

Subcarrier

Frequencies:

Modulati

on

Method:

Modulation

Capability:

Inj

ectio

n

Range:

Muting:

Muting

Sensitivity:

Muting

Delay:

1

-2

105-125

VAC

,

50/60

Hz,

1

,,

15

Watts

o°F

to

120

°F

To

12,

500

ft

.

!

500

Hz

maximum

600

Ohms,

Balanced

+ 10 dbm

::

2

DB

at

400

Hz

for

100

modulauon

! 2

DB

from

50

Hz

to

7500

Hz

(r

eferred

to

75-use

c

preemphasis

)

< L 5%

at

10%

deviation

(SO

Hz

-

7.

5 KHz)

65

DB

below

15%

deviation

41

KHz

and

67

KHz

Direct

FM

"!:

1

5%

of

subcarrle

r

frequency

(10%

deviation

=

100%

modulation)

0 -

30

%

Selectable

at

front

panel

Subcarrier

gate

opens

at

-10 dbm

at

400

Hz

Adjustable

from O. 6

to

4

seconds

,

nominal

098-7070-0l

I

www.SteamPoweredRadio.Com

I

Mode

l 683

2-1

INSTALLATION PLANNING

SECTION

II

INSTALLA

TIO N

Section

ll

Di

mensions

essential

fo

r

pro

per

installation

of

the

Mode

l

683

SCA

Generator

are

show

n

in

Figure

2-1.

2-

1.

1 ENVIRONMENTAL REQUIREMENTS

Locati

on

of

th

e

Mode

l 683

must

be

within

th

e

following

environme

nta

l

limitation

s:

a.

Maxi

mum

altitude:

12,

500

ft.

b,

Max

imum

temperature:

12

0°r

c,

Mi

nimum

temperature

:

oor

d,

Maxim

um

humidity:

95

%

2-1.2

POW

ER

REQUIREMENTS

10

5-12S

VAC,

50/60

Hz

, l

J6

is

required

to

operate

the

Mode

l

683.

Since

this

unit

uses

v

ery

littl

e

power

(1

5

watts)

it

can

remain

p

ermanentl

y

connected

to

the

AC

lin

e

and

l

eft

operational

.

Should

you

desire

to t

urn

it

on

and

off

with

lhe

transmitter

you

shou

ld

allow

at

least

30

seconds

for

the

devi

ce

to

stabilize

before

program

operation

begins.

Sho

uld

it

be

necessary

to

operate

this

equipment

from a

230

volt

sou1

cc

u

se

a

step

-

down

transformer

such

as

a

Triad

N-G8X

.

It

is

important

that

an

auto

-

tran

sformer

.!!Ql_be

u

sed

.

2- 1. 3 COOLING REQUIREMENTS

Wh

en

used

with

the

companion

680

exciter

the

SCA

generator

shou

ld

be

mounted

under

the

exciter.

It

i s

important

that

the

SCA

generator

be

mounted

as

close

to

th

e

exci

t

er

as

p

ossib

le

.

When

used

to

r

etrofit

older

trans

m

itters

it

is

wise

to

l

ocat

e

the

SCA

generator

and

the

exciter

in

a

rack

adjacent

to

th

e

tr

a

nsmitt

er

, Io

this

way

you

can

be

assured

that

th

e

sensit

i

ve

circUitry

with

in

this

equipment

is

k

ept

away

from

the

fields

of

motors,

transf

o

rmers

and

high

current

carrying

conductors

that

might

exist

wit

hin

the

tran

sm1

tler

.,

2

-2

INPUT AND OUTPUT CONNECTIONS

All

input

and

output

connections

fo

r

the

Mode

l

683

a re

made

at

th

e

rear

of

the

unit

and

are

noted

on

fi

gure

2

-1

.

Pri

mary

power

is

connected

to

terminals

J

and

2

of

TB-1.

Remote

control

of

th

e

SC

A m

uti

ng

function

is

accomplished

by

a

contact

cl

osu

re

across

terminals

7

and

8

of

TB-1.

The

audio

frequency

input

connections

a re

terminals

l

and

2

of

TB-1.

The

telemetry

input

connections

are

terminals

Sand

6

of

1'B-1.

098-7070-01

2-1

www.SteamPoweredRadio.Com

Section

II

Mol!el

683 I

I

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-

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I

~~

- -

~

I

2-2

09

8-70

70-01

I

www.SteamPoweredRadio.Com

I

Mod

e l

683

SECTION Ill

OPERATION

3-1

OPERATING CONTROLS AND INDICATORS

Section

III

There

are

onl

y

five

front

pan

el

controls

on

the

Model

683

SCA

Generator

-

illustrated

on

the

drawing

below

.

As

supplied

from

the

factory

the

Model

683

is

ready

for

operation

and

once

the

prope

r

power

and

in

put

conn

ections

are

mad

e

it

can

be

placed

into

service

.

Out

put

leve

l

control

(R-3)

should

be

set

for

the

proper

modu

lati

on

l

eve

l

as

Indicated

on

an

approved

moni

tor

. R- 2

will

set

the

frequency

to

the

desired

value

. 1f

automatic

muting

is

desired

the

subcarrie

r

control

switch

S2

should

be

set

to

auto

.

The

SCA

carrier

will

then

tu

rn

on

and

off

as

audio

is

applied

-

the

muting

turn

-

off

time

determ

in

ed

by

the

setting

of

R- 1

(m

uting

delay

).

NOTE :

Telemetry

tones

do

not

have

sufficient

le

ve

l

to

pr

ovide

the

automatic

control

featu

re -

ii

the

SCA

unit

i s u

sed

for

telemetry

only

the

unit

should

be

turned

on

and

off

by

a

re

l

ay

closure

ac

r

oss

the

"enab

le ''

terminals

-

7

and

8

on

TB

-1.

A

co

mplete

setup

procedure

ls

included

in

the

maintenance

section

of

this

manual

.

.S

- 1

T

3

,</t;8

l

f=t-L:=!h:::!!:::=========================i==t'==t=@======ll:=L:

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.

(7()

I

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------

-

-----

/8.S0/

-9._00

__

/-;-----,,-

--,--------

.1

RB;;

J

LR/

.'3~

098-7070-01

FRONT

VIBW

-MODEL

683

FIGURE 3- l

3-1

www.SteamPoweredRadio.Com

I

Mode

l

683

4-

1 INTRO

DUCT

ION

SECTION

IV

PRI

N

CIPLES

OF OPER

ATION

This

section

describes

the

principles

of

operation

of

the

Model

683 SCA

Generator.

4

-2

GENERATOR

CIRCUIT

DI:SCRIPTION

Section

IV

I

nasmuch

as

the

41-KHz

SCA

module

and

th

e

67-KHz

SCA

module

have

similar

circuitry,

th

e lollO't,ling

discu

ssion

applies

equally

to

both

units

.

The

diffe

re

nc

e

table

on

the

schematic

specifies

those

components

used

for

ope

rati

on

at

eithe

r

fr

equency

.

I

ncoming

audio

is

fed

to

a 10

db

r

esistive

pad

that

is

followed

by

transformer

Tl.

The

circuit

board

cont

ains

provision

for

an

optiona

l

5-KHz

low-pass

filter

for

use

with

the

67-KHz

SCA

module

when

t

he

exc

it

er

is

equipped

with

a

stereo

generator.

The

filt

er

conn

ec

ts

to

terminals

20, 21,

and

22,

and

th

e

jumper

shou

ld

be

r

emoved

from

between

terminals

20

and

21 .

The

emitter

circuit

of

Ql

cont

a

ins

the

preemphasis

and

rolloff

networks.

The

75-usec

preemphasi

s

n

etwork

consi

s

ts

of

Rl2

and

C4,

and

high-frequ

e

ncy

rolloff

is

provided

by

the

network

o!

Ll

and

Rl0.

Th

e

preemph

as

is

time

constant

may

be

chang

ed

to

150

usec

by

changing

t

he

value

of

C4

to

O.

33

uF

.

Telem

e

try

ton

es

can

be

inject

ed

into

th

e

emitter

of

Ql

from

termina

ls

on

the

rear

panel

of

the

unit.

Emitt

er

-

follower

Q2

is

used

to

d

riv

e

the

mutin

g

amplifier

and

the

subcarrier

modulated

osclllator.

Modul

at

ed

oscillator

O10-Qll

is

a

free-running

multivibrator,

the

frequency

of

which

is

proportional

to

it

s

bias

voltage

.

Transistor

09

regulate

s

th

e

bias

to

compensate

for

temperature

drift.

The

modulated

osc

ill

at

or

is

fo

ll

owed

by

diode

gate

CRS-CR6,

buffer

amplifier

Q l

2,

and

a

low-pass

filter

which

removes

harmonics

of

the

oscill

a

tor

waveform

.

Th

e

output

of

the

filter

is

f

ed

to

emitter-

follower

013

.

Subcarrier

contro

l

switch

S- 2

is

mounted

on

th

e

front

panel.

This

switch

provides

a

choic

e

of

three

op

erating

condition

s: ON , OFF,

and

J\UTO. Th

ese

designations

relate

to

muting

the

subcarrier

.

In

th

e AUTO

position,

th

e

subcarrie

r

is

automatically

muted

when

there

is

no

aud

io

input

in

to

the

SCA

module.

Th

e

muting

amplifier

composed

of

03

through

08

gates

the

subcarricr

on

with

normal

audio

i

nputs

of

20

db

or

l

ess

below

peak

deviation

capability

, The

subcan1er

remains

on

for

a

short

period

(

no

mina

lly

b

etwee

n

O.

'6

and

4

seconds

)

after

the

audio

in

put

is

removed;

the

duration

of

the

period

ls

adjustable

by

muting

delay

control

R4

l .

4-3

POWER SUPPLY

CIRCUIT

DESCRIPTI

ON

A r

egulated

power

supp

ly

serves

the

DC

power

needs

of

all

stages

.

The

operation

ts

as

follows

-

the

positive

(

+)

input

of

operation

amplifier

4IC1

is

main

t

ained

at

some

iixed

vo

ltage

by

the

action

of

zener

diode

4D5.

Curren

t

flows

out

of

this

amplifier

into

the

b

ase

of

se

ries-pa

ss

tran

s

istor,

401.

This

causes

its

emitter

voltage

to

ri

se

.

The

voltage

will

rise

until

the

negative

(-)

input

of

the

opera

tion

al

amplifier

r

eceives

a

voltage

from 4R3

that

exceeds

the

zene

r

voltage

at

the

positive

(+)

Jnput,

At

t

his

point

th

e l

eve

l s

will

stab

ilize

so

that

ju

s t

enoug

h

current

fl

ows

out

of

tJ1e

operational

amplifier

into

401

to

maintain

tMs

condition

.

Since

th

ere

is

a

grea

t

deal

of

gain

enclosed

within

this

negalivc-feed-

b

ac

k

loop

,

th

e

output

volt

age

will

r

emai

n

very

stable

for

large

changes

in l

oad

curr

e

nt

or

supply

voltages.

The

input

voltag

e

to

this

re

gulator

is

supplied

by

a

conventional

bridge

r

ectifier

a nd

filter

capacitor.

098-7070-01

4-1

www.SteamPoweredRadio.Com

I

Mo

d

el

683

Section

V

5-1

PERIODIC MAINTENANCE

SE

CTIO

N V

MAINTEN

A

NCE

No

specia

l ma

int

enance

procedures

are

nec

essary,

The

Model

683 SCA

generator

ls

des

i

gned

with

comp

onents

that

should

not

ex

hibit

problems

throughout

the

lif

e

of

the

equipment

.

None

of

th

e

active

d

evices

are

operating

with

parameters

kn01Nn

to

cause

time

-

dependent

fa

ilur

e

modes

,

The

to

p

cover

sh

ou

ld be r

emoved

and

the

dust

blown

out

of

the

generator

using

a

soft

bl

ast

device

such

as

a

vacuum

cleaner

rather

than

an

air

compressor.

Remember

to

re-install

th

e

cover

and

all

screws

after

cl

eaning

.

5- 2 ALIGNMENT AND ADJUSTMEN1' PROCEDURE

If

t

he

SCA

gene

r

ator

requi

res

adjustment

H should

be

performed

only

by

experienced

person

nel

havin

g

an

adequate

understanding

of

the

generator

and

who

are

thorouyhly

familiar

with

the

test

equipm

ent

requi

r

ed

.

5-2

. 1

TEST

EQUIPMCNT

(1)

LOIN

distortion

/\udio

fr

equenc

y

Generator

(2)

Wideband

Oscilloscope

(3)

Accurate

VOM

(

'1)

SCA

Monitor

(5) SHIELDED Audio

leads

for

t

est

conn

ections

(6)

G.

C .

9302

/\ligment

too

l

{7)

l

foot

len

gth

of

RG-58U

cab

le

with

BNC

Connector

s

5-2.

2 ALIGNMENT PROCEDURE

Kr

ohn-Hite

4200

or

equiva

l

ent

T

ektronix

422

or

equiva

l

ent

Si

mpson

260

(1) Remove

the

SCA

Generator

from

th

e

transmitter

, r

emove

the

t

op

cove

r,

and

place

th

e

unit

on

a

test

bench

(2)

Conn

ec

t

117

VAC

to

terminals

to

1

and

2

of

'rB-

1

(3)

Conn

e

ct

wideband

oscilloscope

to

Jl

using

a

I-foot

length

of

coaxial

cable

098-7070-01

5-1

Sparta 683 User manual

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