TFT EBS 760 Series Manual de servicio

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I

,

operating

and

Service

Ma

,

nua

:1

EBI

IYITEffl

fflODEt

760

TIMEAND FREQUENCY

TECHNOLO,

GY,

INC.

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Warranty

TIME

&

FREQUENCY

TECHNOLOGY,

INC.

,

warrants

each

of

the

in-

struments

of

its

manufacture

to

be

produced

to

meet

the

specificationsdelivered

to

the

BUY

ER:

and

to

be

free from defects in

mater

ial

and

workmanship

and

will

repair

or

replace,

at

its expense, for a

period

of

one

year from

the

date

of

delivery

of

equipment,

any

parts

wh

i

ch

are

defective from faulty

material

or

poor

workmanship.

I

nstruments

found

to

be

defective

during

the

warranty

periodshall

be

returned

to

the

factory with

transportation

charges

prepaid

by

BUYER.

It

is expressly agreed

that

replacement

and

repair

shall be

the

sole remedy of

BUYER

with respe

ct

to any

nonconforming

equipment

and

parts

thereof

and

shall

be

in

lieu

of

any

other

remedy

available by applicable

law

. All

returns

to

the

factory

must

be

authorized

by

TFT

,

prior

to

such

returns.

Upon

examination

by

the

factory, if

the

instrument

is found

to

be

defective,

the

unit will

be

repaired

and

returned

to

the

BUYER

,

with

transportation

charges

prepaid

by

TFT.

Transportation

charges for

instruments

found

to

be

defective within

the

first

th

i

rty

(30) days

of

the

warranty

period will be

paid

both

ways by

the

TFT.

Transportation

charges for

warranty

returns,

wherin

failure is found

not

to

be

the

fault

of

the

SELLER,

shall

be

paid

both

ways by

the

BUYER.

This

Warranty

does

not

apply

to

instruments

which, in

the

opinion

of

the

SELLER

, have

been

altered

or

misused.

NO

OTHER

WARRANTY

IS

EXPRESSED

OR

IMPLIED

.

TFT

IS

NOT

LIABLE

FOR

CONSEQUENT

I

AL

DAMAGES.

Claim for

Damage

in

Shipment

.

Your

instrument

should

be

inspected

and

tested as soon as it is received.

The

instrument

is insured for safe delivery. If

the

instrument

is

damaged

in

any

way

or

fails

to

operate

properly,

file

a

claim

with

the

carrier,

or

if

insured

separately, with

the

in-

surance company.

WE

SINCERELY

PLEDGE

OUR

IMMEDIATE

AND

FULLEST

COOPER-

ATION

TO

ALL

USE

RS

OF

OUR

PRECISION

ELECTRON

IC

I

NS

TRUMENTS.

PLEASE

ADVISE

US

IF

WE

CAN

ASSIST

YOU

IN

ANY

MANNER.

fflEffL

TIME

AND

FREQUENCY

TECHNOLOGY, INC.

3000

Olcott

St.

Santa

Clara,

CA

9 5

051

40

B

-2

4

6-

6

365

I

J

I

•

I

••

I

www.SteamPoweredRadio.Com

' .

IMPORTANT

MODEL

NO

. 760

REVISION A

Effective

Serial

No. 1000

MODEL 760 MANUAL CHANGES

2.

4

Antenna

Installation

Delete

Resistor

Figure

6-2

AM

Receiver

(Schematic

only)

AD:p X 100 KHz,.

~

1MHz

and

Xl.0 KHz

to

S1

as

Shown

SI

XIOOKt\z

I

: I

XI

Ml-12.

.

8

4

2.

I

XI

-z.

•, · .·.

•·

•l

,

Figure

6-3

., 1

FM

Receiver

(Schematic

only) .

1 , • •

ADD:

Line

from

the

junction

of

Zl-6

'

and

R43

to

center

tap

of

L3

·'

!

-'.

Figure

6-:-4

Tone

Generator

(Schematic

&

Material

List)

. ,Change: .

C2

lO00pf

Part

No. 1005-1000

to

a 1200pf

Part

No.

1007-0012

Figure

6-5

Tone

Decoder

(Schematic

&

Material

List)

REMOVE:

Fl

a 2A

Slo

Blo

Fuse,

Part

No

.

1900-0002,

Replaced

with

a

jumper

Figure

6-6

Dual

Purpose

Decoder

(Schematic

&

Material

List)

REMOVE:

Fl

a

2a

Slo

Blo

Fuse,

Part

No.

1900-0002,

replaced

with

a

jumper

CHANGE: P .

C.

Board

No. 6609-0970

to

6608-0970

CHANGE: Switch

Sl,

reverse

nomenclature

of

LISTEN/OPERATE

CHANGE: On

Material

List

Z3

to

a 74132

Part

No.

1100-4132

CHANGE: On

Schematic

C27

from

a 7000µf

capacitor

to

a8000µf

capacitor

www.SteamPoweredRadio.Com

-.,,,--,.._

IMPORTANT

MODEL

760 MANUAL CHANGES

MODEL

NO.

7G0

REVISION B

Effective

Serial

No

. 1000

2.

4

Antenna

Installation

Figure

6-2

Sl

Figure

6-3

Figure

6-4

Figure

6-5

Figure

6-6

Figure

2-1

Delete

Resistor

AM

Receiver

(Schematic

and

Material

List)

ADD X 100

KHz,

X

1MHz

and

XlO

KHz

to

Sl

as

Shown

8

4

2

I

')(\00

1(1,1-z.

t

')(.\MHZ.8

4

'l

I

X

10

\(~?.

Change:

Ql

40841

Part

No.

1271-4084

to a 40673

Part

No.

1271-4067

Change:

R14

330Q

Part

No

.

1065-0330

to

a 240

QPart

No.

1065-0240,

factory

select.

FM

Receiver

(Schematic

only)

ADD:

Line

from

the

junction

of

Zl-6

and

R43

to

center

tap

of

L3

Tone

Generator

(Schematic

&

Material

List)

Change:

C2

l000pf

Part

No.

1005-1000

to

a 1200pf

Part

No.

1007-0012

Tone

Decoder

(Schematic

&

Material

List)

REMOVE:

Fl

a

2A

Slo

Blo

Fuse,

Par

t

No.

1900-0002,

replaced.

with

a

jumper

Dual

Purpose

Decoder

(Schematic

&

Material

List)

REMOVE:

Fl

a

2A

Slo

Blo

Fuse,

Part

No

.

1900-0002,

replaced

with

a

jumper

CHANGE:

P,

C.

Board

No.

6609-0970

to

6608-0970

CHANGE:

Switch

Sl,

reverse

nomenclature

of

LISTEN/OPERA

TE

CHANGE:

On

Material

List

Z3

to

a 74132

Part

No.

1100-4132

CHANGE: On

Schematic

C27

from

a 7000µf

capacitor

to

a 8000µf

capacitor

CHANGE:

As

Shown

Below

TFT

MODEL

760

K1:

POTTER

&

BRUMFIELD

R10-E1-Y2-

V185. TOTAL

RELAY

CURRENT

MUST

NOT

EXCEED 250

mA

.

www.SteamPoweredRadio.Com

-

..........

APPLICATION

BULLETIN:

75-02

TO:

Model 760 EBS

System

Users

FROM:

F.

Stolten,

Customer

Service

Manager

DATE:

December

15,

1975

SUBJECT:

Automatic

Reset

of

Two-Tone

Generator

TFT

has

recently

received

inquiries

from

the

field

requesting

information

on

how

to

modify

the

Model

760-04

Two-

Tone

Generator

to

make

the

RESET

automatically

function

after

the

23. 5

second

two-tone

transmission

period.

This

change

is

desired

because

some

broadcasters

want

to

make

EBS

announcements

on

their

nprmal

program

line

and

thus

do

not

want

to

manually

reset

the

Two-

Tone

Generator

after

each

tone

transmission

before

making

Emergency

announccments

-

-or

maybe

forget

to

reset??

There

are

several

ways

to

implement

the

automatic

reset.

. One

way

is

to

modify

the

generator

directly.

This

is

done by

removing

C20,

lµf,

and

placing

a

0.

22µ.f

capacitor

between

Z3

pin 11 and

Zl

13.

An

alternate

approach

to

automatically

rcsef

the

generator

would

be:

1.

Do

not

route

the

normal

program

audio

through

Kl

on

the

Two-Tone

Generator.

2.

Connect

a

pair

of

lines

from

the

AUDIO

OUTPUT

terminals

of

the

Two-

Tone

Generator

to a

mixer

on

the

audio

console

.

This

would

inject

the

,

two-tone

's

on

the

program

iine

without

interrupting

it.

However,

the

Generator

must

be

reset

either

manually

or

automatically

before

the

transmission.

. ;

..

.

I •

r

':-,

.

',J;

r

I •

,.

..

II

•

r

1

'I

.

..

,

..

www.SteamPoweredRadio.Com

Sect.Ion

'1

Table

af

Cant:ent:s

caeneral

Informal.Ion

1.1

General

Description

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

.

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

.

1.2

Specificaitons

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

....

...

..........

....

.

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

.

7.2.1 Model 760-07

AM

Receiver

......

.

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

...

......

.

.......

.

1.2.2 Model 760-02

FM

Receiver

.

......

.

..

.

..........

.

........

. .

..

...

.

.........

.

7.2.3 Model 760-03 Tone

Decoder

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

.

......

.

..

.

...

. . .

..

.

...

.

.........

.

Page

1-1

1-2

1.2.4 Model 760-04 Two-Tone

Generator......

. . .

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

.

...

......

.

..

1-2

7.2.5 Model 760-05 Dual

Purpose

Decoder..........

.

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

. . .

..........

1-2

Sect.Ion

12

lnat.allat.lon

2.1

Unpacking

and

Inspection

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2

Power

Requirement

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3

Installation

and

Hookup

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3. 7

Receiver

AM

or

FM

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3.

7d

External Carrier Fail Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3.2 Two-Tone

Generator

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3.2b Combined

AM/FM/TV

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . 2-1

2.3.3 Tone

Decoder

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3.4 Dual-Purpose

Decoder

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2

.4

Antenna

Installation

2-4

Sect.Ion

3

Dperaclon

Sect.Ion

4

Section

15

3.1

General

......

...

.

...

....

.

.........

.

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

.

....

...

. .

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

.

3.2

AM

Receiver

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

. .

........

.

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

.

......

.

.....

.

3.3

FM

Receiver

.........

.

....

.

...

.

....

. . .

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

.

..........

.

.....

.

3.4

Two-Tone

Generator

...

.

.........

. . . . . .

..........

.

....

. . . .

..

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

. .

3.4.1 Basic Operation

........

.

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

.

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

..

........

.

3.4.2 Remote Control .

......

.

..........

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

...........

. . .

..

.....

.

3.4.3 External Audio Switching .

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

...

. .

.....

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

.

...

.

..

. . .

...

.

.3.5

Tone

Decoder

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

.

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

. .

3.6

Dual

Purpose

Decoder

..

.

......

.

.....

...........

..

.....

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

. .

Theory

of

0peraclon

4.1

System

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

.

........

.

........

.

......

. . .

....

.

..........

.

4.2

AM

·

Receiver

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

.

4.3

FM

Receiver

.......

.

.........

.

...

....

...

.

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

. .

..

......

.

..

. . . . .

4.4

Two-Tone

Generator

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

. . .

...........

.

..

.

....

.

......

...

.....

.

4.5

Tone

Decoder

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

.

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

.

.........

.

4.6

Dual

Purpose

Decoder

Malncenanca

5.1

General

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

.

..........

.

....

.

.....

.

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

...

.

3-1

,3-1

3-2

4-1

4-2

5-1

5.2

Periodic

Maintenance

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.

.3

Performance

Checks........

.

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

.

...........

. .

..

...

.

..

5-1

5.3.1

AM

Receiver

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

5-1

5.3.2

FM

Receiver............

.

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

. . . .

...........

.

......

5-1

5.3.3 Tone

Decoder

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

5-1

5.3.4 Two Tone

Generator

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . 5-1

5.3.5 Dual

Purpose

Decoder

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Section

B

Schematic

Diagram•

6.1

Block

Diagram

6.2

AM

Receiver

.,.......,.,_

*6.3

FM

Receiver

6.4

Two-Tone

Generator

6.5

Tone

Decoder

*6.6

Dual

Purpose

Decoder

*These Diagrams

are

only included when applicable.

www.SteamPoweredRadio.Com

Section

1

General

Information

1.1

General

Description.

The

TFT

EBS System

is

designed to meet the

FCC

Two-Tone

EBS interstation signal

ing

require-

ments. It normally consists

of

three modules-

the

model

760-04

Two-Tone

Generator,

the

Model 760-01

AM

Receiver

or

the

Model 760-02

FM

Receiver,

and

the

Model 760-03

Tone

Decoder-

mounted

in

a

cabinet

for

installation in a 19-i

nch

relay rack.

1.2

Specifications.

EBS

Cabinet

Assembly

Module

Capacit

y

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

.

.....

....

.

Input

Power*

....

, . .

..

.

...

.

....

.

...

..

. . . .

Operating

Temperature*

.........

.

...

. . . . .

Operating

Humidity*

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

.

...

.

Size

.....

..

.....

....

.

......

.

......

...

..

.

Weight .

......

. .

..

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

. . .

...

. .

7.

2.

7

Model

760-07,

Frequency-Synthesized

AM

Recei

ve

r

FrequencyRange

......

.

....

.

....

.. ..

. . . . .

Local OscillatorStability

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

• . .

..

Tuning

Method

...

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

.

.......

. . .

Antenna

Input

...........

.

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

.

Sensitivity .

...

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

..

. .

..

....

.

Image Rejection

......

.

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

. .

AGC

..

.........

.

......

.

.......

.

.......

.

IF

Bandwidth, 6dB . .

...

.

....

...

. .

..

.....

.

Harmonic

Distortion

...

..

.....

. .

......

.

Noise

...

.

......

..

.

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

. . . . .

Audio

Outputs

, 600

ohms

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

. . .

Carrier-Off

Output

..

. . .

...

. .

.........

,

..

.

7.2.2

Model

760

-

02,

Crystal

Controlled

FM

R

ece

i

ver

FrequencyRange . ,

.......

. .

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

. .

Channel Frequency . .

....

...

..........

.

..

.

Antenna

Input

.

....

.

...

..

. .

...

......

...

. .

Sensitivity

....

.......

.

..

•.

...

.

..........

.

IFBandwidth, 6dB

...

.

..

.

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

.

Image Rejection

.....

...

. . . .

.......

.

...

. . .

AGC

.

......

.

.....

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

.

....

.

Audio Frequency Response

.....

.

....

...

.

Harmonic

Distortion

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

.

S/N

Ratio

........

. .

..

...

..

...

. . .

.......

.

*Specifications

apply

to

all system modules.

1-1

An emergency two-tone signal received from

the

AM

or

FM

station

being monitored will be

heard

on

the

EBS System

speaker

after

such

a tone has been received

for

at

least 8 seconds.

The

EBS System provides the

means for interruptingnormal

programming

and

broad

-

casting

the

two-tone emergency signal for 23.4 seconds,

and

for

inserting

emergency

announcements. Normal

operation

can

be restored by

operation

of

two reset

switches.

willaccept

up

to

three

EBSmodules (Models 760-01, -02,

-03, -04,

and

-05). Blank panels

are

provided when fewer

th

an

three

modules

are

in

use.

117

VAC

±

15

%,

50/60

Hz

, 20 watts maximum.

0 °

to

50

°C.

95% Relative..

3.5"

(8.9 cm) high x

19"

(48.3

cm

) wide x

12"

(30.5 cm)

deep.

Approx. 10

pounds

(4

.5 kg)

540-1620

kHz

±500

Hz

per

year

Channel

frequency digitally set m 10

kHz

steps by

thumbwheel switches.

75

ohms

nominal, unbalanced.

30

µ V for 20 dB

S/N

at

30% modulation.

SO

dB

70

dB

±5

kHz

Less

than

3%

at

90% modulation.

45

dB

or

greaterbelow100%modulationwith 10

MV

RF

Balanced:

+8

dBm. Unbalanced: 1 V

rms

Active pullup

to

10

V, 10

ma

88-108

MHz

Speci

fy

frequency, either

one

or

two channel versions

available.

75

ohms

nominal, unbalanced.

2 µ V for 30 dB

of

quieting.

±150

kHz

40 dB

80 dB

±1

dB, 50

Hz

-15

kHz

1%

60

dB

or

greater below 100% modulation

at

SO

µV

RF

i

nput

www.SteamPoweredRadio.Com

I

••

I

~

I

De-emphasis

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

. . .

Audio

Outputs,

600

ohms

....

.

..

.

.........

.

Carrier-Off

Output

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

.

..

.

...

.

1.2.

3 Model

760-03,

Two-Tone

Decoder

Input

Le

vel

Requir

ed

..

.....

......

..

.....

. .

Tone

Frequencies"'*

.......

..

.....

.

......

. .

Bandwidth**

.....

......

. .

....

.....

.

Listen

Operate

Switch

.........

.

..........

.

Audio

Output

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

.

..

.

....

.

..

.

Re

set Switch

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

. .

Remote

Operation

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

.

Time

DelayforDe-muting"'* .

...

.

.........

.

External

Alarm

Cont

ra

cts

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

.

1.2

.4 Model

760-04

, Two-Tone

Generator

Output

Frequencies"'* . .

......

..

..........

.

Frequency Accuracy*"'

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

.

Output

Level

...........

.

.....

.

..

.

......

.

Output

Impedan

ce

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

..

........

.

Harmoni

c Distortion"'*

.........

.

.........

.

Tone

Duration••

....

..........

.

.......

..

.

Tone

Level Adjust**

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

.

.......

.

Program Audio Routing

.....

.

.. ..

.....

...

.

Emergency

Program

Audio I

nput

...

.

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

......

.

Test

Switch

...

.

...........

.

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

. .

Tone

Switch

......

.

.....

.......

. . . .

.....

.

Command

Switches

...

•

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

ResetSwitch ,

.......

.

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

..

. .

Remote

Operation

. . . •

........

. .

..........

l.2.5 /lfudel

760-05,

Dual-Purpo

se

Decoder

75 µ sec

Balan

ced:

+8

dBm.

Unbalanced:

I V

rms

Active

pullup

to

IOV,

10ma.

l00 mV into 600

ohms

053

Hz

and

960

Hz

±5

Hz

In

Operate

mode

the

loudspeaker

is

muted

until

an

EBS

alert

is decoded.

fn Listen mode,

the

loudspeaker

is

demuted

.

I

Watt,

in

ternal

loudspeaker

Resets

decoder

and

mutes loudspeaker

The

RESET

switch wiring is

brought

out

to

the rear

panel.

12

seconds

±4

seconds

SPOT

relay contacts brought

out

to

rear

panel.

853

Hz

and

960

Hz

±0.25

Hz

, crystal controlled

+8

dBm

nominal (per tone)

600

ohms,

balanced

Less

th~n

2%

23.4 seconds,

±0.15

seconds

Front

panel

pot,

-2

dBm

to

+8

dBm

Rear

panel

DPDT

relay contacts. Balanced

input

and

output.

Switchover

and

latch

to

EBS

programming

is

automatic.

Unbalanced

input.

Internally

inserted into

program

line.

Connects

Generator

to De

coder

for testing without inter-

rupting

program

audio.

Enables

one

tone

at

a time for setting level

and

checking

distortion.

2 toggle switches.

Must

be

activated in opposite direc-

tions

to

turn

on

Generator

.

Releases

latch

to restore

normal

program

audio.

The

COMMAND

and

RESET

switch wiring is

brought

to

the

rear

panel.

See

M

ode!

760

-

03,

T

wo

-Tone

Decoder

for

Two-

Tone

Spec1fications

CarrinBrf'ak/

J(XX}

H{Speczfzcations:

Input

Le

vel

Required

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

..

.

Tone

Fr

equency

...

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

. . .

B

andwidth

.....

.

......

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

. .

...

.

Time

to

demute

after

start

of

Carrier

Breaksequence

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

..

.......

. .

..

.

RE

SET

switch

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

..

.

Listen/Operate

Switch .

........

. . .

Audio

Output

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

.

...........

. . .

Remote

Operation

. .

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

.

.......

.

External Alarm

Contacts

......

.

..

.......

.

100 mV into 600 ohms

1000

Hz

±50

Hz

23

to

27

sec.

Resets decoder

and

mutes

loudspeaker.

fn

Operate

mode

the

loudspeaker is muted until

an

EBS

alert

is

decoded. In List

en

mode

the

loudspeaker is

demuted.

1

Watt

,

internal

loudspeaker

The

RESET

switch

is

brought

out

to

the

rear

panel.

SP

OT

relay contacts

brought

out

to

rear

panel.

Specifications

are

typical except those identified by ** which

are

guaran

teed.

1-2

www.SteamPoweredRadio.Com

Section

2

Installation

2.1 Unpack

ing

and

Inspection.

Upon

receiving

the

instrument, inspect

the

packingbox

and

instrument

forsi

gns

of

possible

sh

i

pping

damage.

Operate

the

instrument

in

accordance

with

the

procedures

of

Section3

of

this

manual.

If

the

instrument

is

damaged

or

fails

to

opera

te

properly, file a claim

with

the

t

ransportation

company,

or

with

the

insurance com-

pany

if insured

separate

ly.

2.2

Power

Requirements.

The

Model 760

EBS

System

operates

from a

117-volt Ac Source.

The

line frequency

must

be

between

50

and

60

hertz.

Maximum

power

requ

i

red

is 20 watts.

2.3 Installation

and

Hookup.

When

the

EBS

System

Cabinet

assemb

ly is

mounted

in a 19-inch relay

rack

with

all modules in

place,

make

the

following connections

to

the

module

terminalstripsat

the

rear

of

the

cabinet. Afterall connec-

tions have

been

made,

plug

the

power

cord

into a 117-

volt, 60-hertz source.

There

is

no

power switch in

the

system: it is energized wheneverits power

cord

is

plug

g

ed

m.

2.3.7 R

eceiver

AM

or

FM.

2.3.2

ii-

a.

If

an

AM

or

FM

Receiveris installed,

connect

a

75

ohm

coax cable from the

antenna

to

the

rear-panel

ANTENNA

connector.

,.~

b.

Connect

the

rear-panel

UNBAL

AUDIO

terminal

to the

DECODER

AUDIO

I

NPUT

terminal.

c.

If

desired,

the

rear-pan

el

BALA

NCE

D

AU

DIO

t

erminals

can

be

connected

to

a

monitor

or

other

device.

Output

at

these

terminals is

+8dBm

at

600

ohms

for 100%

modulation.

d.

ff a remote indication of

car

rier fail

ure

is

to

be

provided, connect

the

rear-panel

CARRIER

FAIL

termina

l

to

the

remote indicator.

Output

from

th

is terminal

is+

10 volts @ 10

ma

for

normal

carrier

level,

and

O volts wi

th

5

ma

current

sinking for

car

rier

failure. For

operating

an

external

carrier

fail

ala

rm relay, see Figure2-

1 for suggested circuit. Total external relay

current

must

not exceed 250 ma.

Two-

Tone

Generator.

a. If

the

monaural

program

audio

is

to

be

looped

through

the

Two

-

Tone

Generator,

connect the

program

input

line

to

the

rear

-panel

AUDIO

IN terminals

and

connect t

he

program

output

li

ne

to

the

rear-panel

AUDIO

OUT

term

inals.

b.

If

the

program

line

is

not

to

be

looped

2-1

TFT

MODEL

760

EXTERNA

AUDIO

RELAY

K1: POTTER

Ii

BRUMFIELD

R10-E1-

Y2

-

V185. TOTAL RELAY

CURRENT

MUST NOT

EXCEED

250

mA.

Fi

gure

2

-1

through

the

Two

-T

one

Generator,

or

if

combined

AM/FM/TV

program

audio

is

to

be

controlle

d,

external

circuitry

like

that

diagrammed

in Figure 2-2

is

recommended.

Relays

Kl,

K2,

and

K3

shown in Figure 2-2

should

have

12

-

vo

lts coils,

and

the

total coil

current

must

not exceed 250 milliamperes.

Relay power

and

EBS

audio

input

come from

connect

or

J2

on

the

rear

panel

of

the

Two

-T

one

Gene

ra

tor

.

c-~

c.

Connect

a wire from

the

rear-panel

TEST

OUT

terminal

to

the

DECODER

TEST

INPUT

terminal.

This

provides a

means

to

test

the

Two

-T

one

Generator

and

Tone

Decod

er

together without interrupting

the

program.

o

'-'-

d.

Connect

t

he

emergency

announcement

audio

line

(unba

l

anced)

to

the

rear

-panel AN

INPUT

terminal.

i~

e.

ff

remote control

of

the

command

and

reset

functions is desired,

connect

the

rear

-

pan

el

COMMAND

and

RESET

terminals

to

remote

switches.

Groundi

ng

the

se

lines activates

the

functions.

NOTE:

Pursuant

to

Section

73.940

(j

)

of

the

FCC

Rules

&

Regulations,

the

remotely

located

command

switch

must

be

guarded

such

as

to

prevent

accidental

operation

.

2.

3.3

Tone

decoder.

ti\L

a.

Connect

the rear-panel

AUDIO

INPU

T

terminal

to

the

REC

EI

VER

UN

BAL

AUDIO

as

previously

stated

in Subsecti

on

2.3.1

b

or

to

another

EBS

monitor

receiver

if

used.

The

sentitivity

of

the

Tone

Decoder

is

factory

adjust

ed

so

that

a 100

per

cent modulatedsignal

(+8

d

Bm

at

the

DECODER

AU

DIO

I

NPUT

terminal) will

produce

10

vo

l

ts

peak

-

to

-

peak

at

the

rear-panel

LEVEL

terminal

when

used with

---------

-

www.SteamPoweredRadio.Com

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

TFT

MODEL

760-04

TWO-TONE GENERATOR

+RELAY

--<+,

J--

------

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

-

RELAY--<'-,

J

----

AUDIO

--<~

AUDIO

--<~

•►

:►

1

kn

◄:

----""------

.

CR

1

•t/

OPERATE

- I -

AM

TEST

1

OFM TEST

O

TV

TEST

J

)

::

1

kn

◄:

----""-""--"----'

I

- I -

CR

2

~•/

- I -

,~

I

~0-------'

I

-

.....

--.0~1-

r--df"

Kl

K2

I

-~

I

◄•

:►

1

kn

◄:

-----+-

+----

◄

I

!

CR3

.3'_,,-

- I -

I

o

I

o

lo---

_

_.

I

- I -

Kl

AM

AUDIO

IN

AM

AUDIO

OUT

FM

LEFT

AUDIO

IN

FM

LE

FT

AUDIO

OUT

FM

RIGHT

AUDIO

IN

FM

RIGHT

AUDIO

OUT

TV

AUDIO

IN

TV

AUDIO

OUT

...

◄

..

200

n

◄"'

TOTAL

RELAY

CURRENT

NOT

TO

EXCEED

250

ma

K1

,

K3

:

POTTER &

BRUMFIELD

R10-E1-

Y2

-V185

K

2:

POTTER &

BRUMFIELD

R10-El·

Y4·V185

CR1, CR2, CR3:

HPA

5082-4487

Figure

2-2

►

TFT EBS 760 Series Manual de servicio

Manuales populares de Receptor de otras marcas