Carver Tx-11b User manual

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CARVER

Model

TX-11b

Quartz-SynthesizedStereoTuner

Ultra

High

Fidelity

Wide

Band

AM

Stereo

AsymmetricalCharge-Coupled

FM

Detector

ThirteenStationPresets

MultipathEliminationCircuitry

Noise

Reduction

CAUTION

RISK

OF

ELECTRIC

SHOCK

DONOT

OPEN

CAUTION:

TO

REDUCE

THE

RISK

OF

ELECTRICSHOCK,

DONOT

REMOVECOVER

(OR

BACK)

NO

USER-SERVICEABLE

PARTS

INSIDE

REFER

SERVICING

TO

QUALIFIED

SERVICE

PERSONNEL

SafetyInstructions

1

ReadInstructions

- Allthe

safety

and

operating

instructions

should

be

readbefore

the

com-

ponent

is

operated.

2

RetainInstructions

- The

safety

and

operating

instructions

should

be

retained

for

future

reference.

3

HeedWarnings

- All

warnings

onthe

com-

ponent

andinthe

operatinginstructionsshould

be

adhered

to.

4

FollowInstructions

- All

operating

and

other

in-

structionsshould

be

followed.

5

Water

and

Moisture

- The

componentshould

not

be

usednearwater

- for

example,near

a

bathtub,

washbowl,kitchensink,laundrytub,

in

a wet

basement;

or

near

a

swimmingpool,

etc.

6

Ventilation

- The

componentshould

be

situated

so

that

its

location

or

position

does

not

interfere

with

properventilation.

For

example,

the

com-

ponentshould

notbe

situated

ona

bed,sofa,

rug,

or

similarsurfacethat

may

block

the

ven-

tilation

openings;

or

placed

ina

built-in

installa-

tion

such

asa

bookcase

or

cabinetthat

may

impede

the

flow

ofair

through

the

ventilation

openings.

7

Heat

- The

componentshould

be

situatedaway

from

heatsourcessuch

as

radiators,

or

other

devicesthatproduceheat.

8

PowerSources

- The

componentshould

be

connected

toa

powersupplyonly

ofthe

type

described

inthe

operatinginstructions

oras

marked

onthe

component.

9

Power-CordProtection

-

Power-supplycords

should

be

routed

so

thatthey

arenot

likely

to

be

walked

onor

pinched

by

itemsplacedupon

The

lightning

flash

with

arrowhead

symbol,

within

an

equilateral

triangle,

is

intended

to

alert

the

user

ofthe

presence

of

uninsulated

"danger-

ous

voltage"

within

the

product's

enclosure;

that

may

beof

sufficient

magnitude

to

constitute

a

risk

of

electric

shock

to

persons.

The

exclamation

point

within

an

equilateral

triangle

is

intended

to

alert

the

user

ofthe

presence

of

important

operating

and

mainten-

ance

(servicing)

instructions

inthe

literature

accompanying

the

appliance.

or

againstthem,payingparticularattention

to

cords

at

plugs,conveniencereceptacles,

andthe

pointwheretheyexitfrom

the

component.

10

Cleaning

- The

componentshould

be

cleaned

only

as

recommended

in

thismanual.

11

Non-usePeriods

- The

powercord

ofthe

com-

ponentshould

be

unplugged

from

the

outlet

when

left

unused

fora

longperiod

of

time.

12

Object

and

LiquidEntry

-

Careshould

be

taken

so

thatobjects

donot

fall

into

and

liquids

not

spilled

into

the

inside

ofthe

component.

13

Damage

RequiringService

- The

component

should

be

serviced

by

qualifiedserviceperson-

nel

when:

A.The

power-supplycord

orthe

plug

has

been

damaged;

or

B.

Objectshavefallen,

or

liquid

has

been

spilledinto

the

component;

or

C.The

component

has

beenexposed

to

rain;

or

D.

The

componentdoes

not

appear

to

operate

normally

or

exhibits

a

marked

change

in

per-

formance;

or

E.The

component

has

beendropped,

orthe

cabinetdamaged.

14

Servicing

- The

usershould

not

attempt

to

ser-

vice

the

componentbeyondthosemeans

described

inthe

operatinginstructions.

All

otherservicingshould

be

referred

to

qualified

servicepersonnel.

15

Powerlines

- An

outdoorantennashould

belo-

catedawayfrompowerlines.

16

To

preventelectricshock

donotuse

this

(polarized)plugwith

an

extensioncord,

recep-

tacle

or

otheroutletunless

the

blades

canbe

fully

inserted

to

preventbladeexposure.

EXAMPLE

OF

ANTENNA

GROUNDING

ACCORDING

TO

NATIONAL

ELECTRICAL

CODE

INSTRUCTIONS

CONTAINED

IN

ARTICLE

810-

"RADIO

AND

TELEVISION

EQUIPMENT"

POWER

SERVICE

GROUNDING

ELECTRODE

SVSTEM

BONDING

JUMPE

OPTIONALANTENNA

GROUNDING

ELECTRODE

a.

UseNo.10AWG

(5.3

mmz)

copper.

No.8 AWG

(8.4

mmz)

aluminum.

No.17AWG

(1.0

mmz)

copper-clad

steel

or

bronze

wire,

or

larger,

asa

ground

wire.

b.

Secure

antenna

lead-in

and

ground

wires

to

house

with

stand-off

insulators

spaced

from

4-6

feet

(1.22-1.83

m)

apart.

c.

Mount

antenna

discharge

unit

as

close

as

possible

to

where

lead-in

enters

house.

d.

Use

lumper

wire

not

smaller

than

No.6 AWG

(13.3

mmz)

copper,

orthe

equivalent,

when

a

separate

antenna-grounding

electrode

is

used.

SeeNEC

Section

810-21

(j).

Carts

and

Stands

- The

appliance

should

be

used

onlywith

a

cart

or

standthat

is

recom-

mended

bythe

manufacturer.

An

appliance

and

cart

combination

should

be

movedwith

care.

Quick

stops,excessiveforce,

and

unevensurfaces

may

cause

the

appliance

and

cartcombination

to

overturn.

PORTABLE

CART

WARNING

Pour

prevenir

les

chocselectriques

nepas

utilisercette

fiche

polarisee

avec

un

prolon-

gateur,

une

prise

de

courant

ouune

autre

sortie

de

courant,sauf

si les

lamespeuvent

etre

inserees

a

fondsans

en

laisseraucunepartie

a

decouvert.

17

Grounding

or

Polarization

-

Precautionsshould

be

taken

sothe

grounding

or

polarization

means

ofthe

component

arenot

defeated.

Section

810

ofthe

NationalElectricalCode,

ANSI/NFPANo.

70-1984,providesinforma-

tion

with

respect

to

propergrounding

ofthe

mast

and

supportingstructure,grounding

ofthe

lead-inwire

toan

antennadischarge

unit,

size

of

groundingconductors,location

of

antenna-

discha'rge

unit,

connection

to

grounding

electrodes,

and

requirements

forthe

grounding

electrode.

Table

Of

Contents

SAFETY

INSTRUCTIONS

3

I.

INTRODUCTION

6

II.

PLACEMENT,INSTALLATION,

AND

REAR

PANEL

CONNECTIONS

.7

III.

CONTROLS

AND

FUNCTIONS

9

IV.

MULTIPATH/NOISE

REDUCTION

ANDTHE

ASYMMETRICAL

CHARGE-COUPLED

FM

DETECTOR™'

...11

V.

ANTENNAS

FM

AM

12

16

VII.APPENDIX

Section

1 FM

Stereo

Signals

andthe

Asymmetrical

Charge

Coupled

FM

Detector

18

Section

2 AM

Stereo

Signals

andthe

Ultra

High

Fidelity

Wide

Band

AM

Stereo

18

Section

3

Specifications

20

Section

4

Troubleshooting

21

Section

5

Warranty

22

•U.S.

Patent4.467,012

IMPORTANT!

The

TX-11

b's

memorypresetswitches

are

sensitive.

Use

a

gentle,on-centertouch,don'tpushthem

too

hard,

or

they

may

jam.

WARNING!

To

prevent

fire

or

shockhazard,

donot

exposethis

equipment

to

rain

or

moisture.

If

you

wish

to

engage

the

NOISE

and

MULTIPATHREDUCTION

switches

simultaneously,

usetwo

fingers.Using

oneon

both

buttonscould

jam

them.

TO

AVOIDELECTRICALSHOCK,

DONOT

OPENCHASSIS.

NO

USER-SERVICEABLE

PARTSINSIDE.REFER

ALL

SERVICING

TO

QUALIFIEDPERSONNEL

CAUTION:Wheninstallingthisequipment,read

and

follow

all

safety

and

operating

instructions.

NOTE!

To

CATV

system

installer

-

Thisreminder

is

provided

to

call

the

CATVsysteminstaller's

attention

to

Article820-22

oftheNEC

thatprovidesguidelines

for

propergroundingand,

in

particular,specifiesthat

the

cablegroundshall

be

connected

tothe

groundingsystem

of

the

building,

as

close

tothe

point

of

cableentry

as

practical.

Personal

WarrantyInformation

Serial

Number:

Dealer:

Date

of

Purchase:

S^

r

Personal

ID

Number/Location:

Introduction

Congratulations!You'vepurchased

the

finesttuneravailable:

the

Carver

TX-11

b

Quartz

SynthesizedStereoTunerwithAsymmetrical

Charge-Coupled

FM

Detector™

and

UltraHighFidelityWideBand

AM

stereo(utilizingMotorola's

CQUAM™

system).Your

new

tuner's

special

FM

circuitry

isBob

Carver'sbrilliantsolution

for

eliminating

the

distortion

and

noise

that

usually

make

FM

listening

a

less

than

pleasurableexperience.Whenengaged,thesepatentedcircuits

enable

the

TX-11

bto

literallypullmusicfrom

the

morass

of

hiss

and

distortionassociatedwithmultipathinterference.You'll

be

able

to

consistently,cleanly,quietlyenjoy

the

music

in

STEREO.

The

ambience

and

localizinginformationneeded

to

perceivestereo,also

lost

to

distortion,

is

restored.Finally,

a

realbreakthroughthatmakes

FM

programming

compete

equally

with

records

and

tapes

for

audio

quality,

and

share

of

yourlisteningtime.

The

TX-11

b has

beenexceptionallyengineered,

andis

superbly

crafted

for

morethansonicexcellence.Yourtuner

has

many

sophisticatedfeaturesthatwillenhanceyourenjoyment

of

stereo

listening,

now,

andinthe

future.

To

takefulladvantage

ofall

this,

be

sure

to

read

the

safety,installation,

and

operatinginstructions.We've

prepared

thisowner'smanual

for

learningabout

the

concepts,

controls,

and

functionsthatmake

the

TX-11

ba

superior

tuner

in

every

way.

We'veincludedevenmoreinformation

on

getting

the

most

from

your

new

tuner.

See

ANTENNAS,

andthe

Appendix

of

thismanual

to

ensure

youare

getting

the

verybestsound

you

deserve.

WarrantyCard

Please,

fill

outand

return

the

WarrantyCardthatcamewith

theTX-

11

b's

packing

kit.

It'shighlyunlikelyyour

TX-11

b

will

ever

need

service,

but

should

the

unlikely

occur,

yourWarrantyCard

isthe

ticket

to

Carver's

two

yearslimitedParts/LaborWarrantyrepair.Eitherfrom

a

localAuthorizedCarverServiceCenter,

orthe

factory.

We

also

suggest

you

fill

outthe

warrantyinformation

inthe

space

we

included

on

the

precedingpage.

Be

sure

to

include

any

personal

ID

number

used

in

furtheridentifying

the

TX-11

b.

Before

Going

any

Farther...

Here

are

somesuggesteddo's

and

don'tsthatwillmakesetting-up

and

using

the

TX-11

ba

safe,

as

well

as

enjoyableexperience:

•

Don'toperate

the

TX-11

b onany

other

power

linevoltageother

than

that

specified

onthe

rear

panel.

•

Make

all

connections

toand

from

the

TX-11

b

with

its

power,

and

power

forall

othercomponents

in

yoursystem,switchedOFF.

•

Unplug

the

TX-11

b's

power

and

antennalead-induringelectrical

storms,

orif

you're

not

going

touseitfora

prolongedperiod

of

time.

•

When

unplugging

theac

linecord,grasp

the

plug

and

pull;

don't

yank

onthe

corditself.

•If

someoneaccidentlyspills

a

drink

onthe

TX-11

b's

cabinet,

unplug

the

tuner

and

have

it

checked

outor

cleaned

bya

qualified

servicetechnician.Thisapplies

to

every

piece

of

equipment

in

your

stereosystem.

•Of

course,we'vementionedthattherearen't

any

user-serviceable

partsinsideyour

TX-11

b.

Please,resist

any

temptation

to

fiddle

aroundinside

the

TX-11

b.

Avoidpossibleelectricalshockand/or

extremeembarrassment.

Refer

all

servicework

toa

qualified

technician.

Again,

keep

the

carton

and

packingmaterial

the

TX-11

b

came

in.

Should

you

move,

the

best

shipping

container

isthe

original

carton.

Hang

onto

this

owner's

manual,

too.Whenyourmusicsystemgets

to

itsnew

home,

the

safety,installation,

and

programminginstructions

could

be

morethanuseful.

Also,

pleasefill

outand

return

the

warranty

card,

ifyou

haven'talreadydone

so.Inthe

remote

possibility

your

TX-11

b

everneedsrepair,

the

warrantycard

isa

passport

to

speedy,

efficientservicefromeither

a

localAuthorizedCarverServiceCenter

or

the

factory.

InstallationCleaning

To

perform

the

basic

installation

and

set-up

ofthe

TX-11

b,

you'llneed

shielded

signal

leads

(dual

RCA

phono

plug

to

phonoplug),

andthe

half-wave

dipole

antenna,

loop

antenna,

and

wirethatcame

inthe

box

along

withthis

manual.

If

you're

planning

to

install

the

TX-11

b

handles,

a

philips-head

screwdriverwill

be

needed.

Placement

Place

the

TX-11

b

near

the

preamp

-

nearenough

sothe

signalcable

willreachwithoutexcessivestrain

onthe

cableitself,

oronthe

connections.

Heat,

at

leastnormalamounts,shouldn't

beany

problem.

The

tuner

itself

doesn'tgeneratemuch

and

isn'tsensitive

to

smallamounts.

But,

you

shouldnevermount

the

TX-11

b

directly

ontopof

power

amplifiers.Unless

your

systemusesCarverMagneticField

Amplifiers,conventionallydesignedampscan,

anddo,

generate

a

lotof

heat.Plus,

the

tuner'schassiscouldblockventsneeded

for

propercooling

ofthe

amps.

If

your

equipmentrack

or

component

cabinet

is

completelyenclosed,forced-aircoolingwith

a

small"rack

fan"willprolong

the

life

ofthe

electricaldevices

in

yourstereo

components.Theserackfansquietlymovebetween

40and

120

cubic

feet

ofairper

minute,come

in

differentsizes,

andmaybe

obtained

from

electronicsupplystores

or

yourstereodealer.

We

also

recommendusing

a

filter

with

the

rack

fanto

minimizedust

inthe

enclosure.

Be

sure

you

clean

the

filterregularly.

Never

mount

or

locate

the

TX-11

b in

directsunlight,nearforced-air

vents,nearmotors,

or

othersources

of

dust

and

possible

interference.

It's

a

goodidea

to

wipe

the

TX-11

b's

cabinetfromtime-to-timewith

a

soft,

dry

cloth.

Ifyou

have

toget

somethingoff,

usea

milddishsoap

or

detergent:don't

use

alcohol,ammonia,

or

otherstrongsolvents.

SignalConnections

When

it

comes

to

makingsignalconnectionsbetween

the

tuner

outputs

and

preampinputs(forintegratedamps,too),

be

sure

to

plug

the

leftsideinto

the

left

tunerinput

ofthe

preamp,

the

rightsideinto

the

righttuner

input.

As

mentionedearlier,

the

signalcable

should

reachwithoutstraining

cable

or

connections.

Inthe

eventthat

the

signalleadsdon'treach,

or

simplyaren'tlongenough

for

yourspecialinstallation,substitute

cables

canbe

obtainedfrom

a

stereodealer

or

electronicsupplyshop.

It'srecommendedthat

any

othercablesused

be

shielded,

andnot

exceed

20

feet

in

length.Thiswillhelpminimizepossiblenoise

or

interference.

Power

Plug

the

TX-11

b

powercordintoeither

a

switched

or

unswitched

convenience

receptacle

ofthe

preamp

or

integrated

amplifier.

Don't

force

the

plug,

doit

carefully.

If

thesereceptacles

are

taken

upby

power

amps,turntables,

or

othercomponents,

a

multireceptacle

power

bar

should

be

used.Plug

the

TX-11

b,and

otheradditional

components

inthe

system,into

the

power

bar

(including

the

preamp

itself).

Makecertain

the

power

baris

rated

to

handle

the

total

maximumwattage

ofallthe

components

in

yourstereosystem.Plug

the

power

bar

into

a

walloutlet.

Make

sure

the

volume-control

onthe

preamp

is

turneddown

oroff

before

switching

onthe

power

ofany

component

in

yourstereo

system.

FM

^

Antenna

input

TX-11b

(red)'

T

(white)

I

'--•R

output

TX-11b

HOOK-UP

DIAGRAM

SignalCable

M

(red)

I

f

(white)

R*

»

L

Tuner

input

PREAMP

or

INTEGRATED

AMP

Grounding

FM

While

grounding

an

outdoorantenna

is

vitallyimportant,there's

normally

no

need

to

ground

the

tuneritself.

But

withsafety

and

possiblyreducedinterference

in

mind,

youmay

want

to

ground

the

tuner

chassis.

Ifso,runa

heavy

(12-gauge

or

heaviercopper/alum.)

wire

from

the

tuner

toa

metal

coldwaterpipe.You'llhave

to

check

to

makesure

the

metalpipe

is

grounded;

PVC

(plastic)pipes

are

somtimes

runin

from

the

watermain

tothe

house,thenmetalpipes

are

usedwithin

the

house.NEVERattach

a

groundwire

toagas

pipe,

either

for

yourcomponents,

or

antenna.

The

bestgroundingscheme

isa

ground

rod

driven

severalfeet

into

the

earth.

Seethe

chapter

on

ANTENNAS

for

information

on

installing

a

groundrod.

Antenna

Terminals

AM

Two

AM

antennashavebeenprovidedwithyour

TX-11

b.

Experimentationwilltell

you

whichantennaworksbest

for

your

location.

Seethe

chapter

on

ANTENNAS

for

furtherinformaton.

AM

LoopAntenna

The

first

isa

highperformance,noise-free

AM

loopantennaheld

on

the

rearpanelwith

a

snap-inhinge.Swivel

itoutfor

bestreception.

You

may

alsoremove

the

antennafrom

its

hinge

and

attach

ittoa

nearbywall.

The

length

ofthe

antennacord

is2

feet

and

should

not

be

pulledtight.

Securely

connect

the

loopantennaleads

totheAMandGND

terminals.

AM

WireAntenna

The

second

AM

antenna

isa

wirethatattaches

totheAM

terminal

of

the

TX-11

b.

Thiswirewillincrease

AM

sensitivity,

andwe

highly

recommend

itsuseforAM

stereoreception.

You

can

either

connect

directly

to

your

local

Cable

Television

System

forFM

(consultyour

Cable

Operator)

usingcoaxial

cable,

orusethe

supplied

75/300

ohm

adaptor

and

dipole

ribbon

antenna.

Cautionshould

be

used

when

connecting

your

Preamp/Tunerto

an

external

outside

TV/FM

antenna.

See

Notice

located

in

the

front

of

this

manual.

If

uncertain,

please

refer

to

qualified

personnel.

Ifhum

occurs

when

using

the75ohm

terminal,

install

a

75/300

ohm

balanced

transformer

tothe

coaxial

cable,

and

reconnect

tothe

supplied

300ohmto75

ohm

adapter

to

break

the

groundloopthat

is

causing

the

offending

hum.

A

commercialcablecompany,

asa

matter

of

procedure

and

policy,

most

oftenconnects

a

tunerusing

the300

n

antennaterminals.

Few

tunershaveprovisions

for

directconnection

to

750

feeds.Normally,

a

feedline

from

a FM

trap

is

connected

with

a

matching

transformer

(75

ftto300ft)tothe300ft

antennaterminals

bythe

cablecompany

installer.Theirtransformerscomewithspadelugs

onthe

leads,

and

arethe

sametypeused

to

terminate

a

regular

TV

cable

attheVHF

antennaterminals

ofaTV

set.NOTE:

It

isn'tlegal

to

"do-it-yourself

andtap

into

a

commercialcable

TV

systemwithouttelling

the

cable

company.

So,

don't

do

it...

even

ifyou

knowhow!

If

youcan

talk

the

installer

intoconnecting

the

cablefeeddirectly

to

the

75ft

terminals,

askto

have

a

female

to

femalecoaxialconnector

insertedbetween

the

mainfeedfrom

theFM

trap

anda

shorterpiece

of

cableconnected

tothe

tuner.Thisprovides

an

easydisconnect

for

the

cable

lead-in,

withoutunhooking

itatthe

TX-11

b's

rearpanel.

This

isan

especiallygoodidea

for

those

who

will

use75ft

coaxial

cablewiththeir

own

antennasystems

for

quickdisconnectduring

electricalstorms.

GND

AM

II

oo

750

•ANTENNA

Controls

&

Functions

FrequencyDisplay

Signal

StrengthIndicator

StereoIndicator

LED

Tuning

Down

Up

Power

On/OFF

FM

AMI

IF

Band

Auto

Tuning

Multipath

Reduction(FM)

Noise

Limiter

(AM)

L

output(white)

NoiseReduction(FM)

RF

Gain(AM)

+

12dB

Antenna

inputs

Power

The

POWERswitch

onthe

lower

lefthand

side

ofthe

TX-11

b

turns

the

unit

onor

off.When

you

power

up,the

tunerwill

be

tuned

tothe

samestation

you

werelistening

to

beforepower

was

switchedoff.

R

output

(red)

ManualTuning

Tuning

What

Happens

When

You

Tune

the

TX-11b?

The

first

inthe

chain

of

eventsthat

goon

inside

a

tuner

isthe

frequency

tuningitself.Here

the

Carver

TX-11

b

uses

a

phase-lockedloopwith

digitallysynthesizedtuningcontrolled

bya

4-bitmicroprocessor.

What

happens

is

this:

a

crystal-controlledoscillatorruns

atan

exact

frequencywhich

is

then

divided

down.Meanwhile,

a

localoscillator

is

tuning

tothe

station'sfrequencywhich

is

lowered

bya

programmable

divider.

The

phase

ofthetwo

reduced

frequencies

is

compared,

and

oncetheymatchexactly,

the

LOCKEDlightgoes

on

and

phase-lockedlooptakesover.

The

phase-lockedloop

isa

circuit

thatcompares

the

phase

ofthe

tunedfrequency

andthe

reference

frequencycontinuously.

Ifthe

tunedfrequencydrifts,

the

comparator

brings

it

rightback.

With

the

TX-11

b on,

press

the

Autotuningmomentaryswitch.

The

Auto

LED

will

go

out,

andyoucan

presseither

the

DOWN

orUP

controlbuttons

to

changefrequencies.

One

pushgets

youa

change

of

0.1

MHz.Holding

the

buttonresults

ina

morerapidchange

of

frequencies.Stopwhen

yougettoa

station'sexactfrequency.

If

you're

not

quite

sure

what

the

exact

frequency

is,usethe

SIGNAL

STRENGTHINDICATORS

and

"LOCKED"INDICATORL.E.D.

If

youtryto

tunelower

or

higherthan

the

frequencylimits(87.5

MHz

low,

108

MHz

high),

the

tunerwill

not

changefrequencies;

you'll

have

to

push

the

othertuningbutton.

The

TX-11

b's

thresholdcircuitry

is

defeatedduringmanualtuning;

this

will

allowreception

ofa

weak

or

extremelydistantstation.More

aboutthis

ina

bit.

Automatic

ScanTuning

Make

sure

the

AUTOtuning

LEDison.

Thenpresseither

theUPor

DOWN

button.

The

tuner

will

change

tothe

or

lower

station

with

a

signalstrongenough

to

defeat

the

mutingcircuitry

oftheTX-

11

b.The

automaticinterstationmutingcircuit

is

engagedduring

tuning

(in

bothMANUAL

and

AUTOmodes).

Ifyou

hold

theUPor

DOWNbuttonsdownduring

the

autotuning,

the

tunerwillskippast

stations

until

youletgo.

"

If

you

scanpast

the

laststation

onthe

dialgoing

inone

direction,

the

tunerwillsearch

totheendofthe

tuningrange,then

"turn

around"

and

start

scanning

inthe

oppositedirection.

NOTE:

In

order

to

receivesignalsbelow

15

\M

(very

low

power,

or

distant

stations),

it

will

be

necessary

to

switch

the

TX-11

bto

MANUAL

tuningotherwisetheselow-strengthstationswill

be

cancelled

bythe

mutingcircuitry.Tunethesestations

aswe

described

inthe

preceding

section

on

MANUAL

TUNING.

Programming

Select

AMorFMby

depressing

the

momentaryswitch

forAMorFM

band.

AnLED

above

the

switchwillindicatebandselection.Simply

tune

toa

station

or

frequency

you

want

to

program.Push

the

MEMORY

button

(onthefar

left

side

ofthe

13

progamswitchesbelow

the

display),

then

anyoneofthe

13

station

presetswitches.

Any

preset

canbe

programmed

forAMorFM.

Onceyou'vepushed

the

MEMORYbutton,

theredLED

above

it

will

stay

litfor

about

ten

seconds,

or

until

you

push

oneofthe

station

preset

switches.

The

station

you

selectedwill

be

stored

inthe

memory.Repeat

the

process

forthe

Rememberthatusing

the

manualtuningmodewillallow

youto

receivemore

distant

stations

or

weakersignals,because

the

thresholdcircuitryisn'toperatingduringmanualtuning.These

stations,

weakand/ordistant,

can

still

be

stored

inthe

TX-11

b's

station

presetmemories.

Programmed

Tuning

Just

press

oneofthe

stationpresetswitchesthat

hasa

frequency

programmedinto

it.

Automaticmuting

will

be

engaged

until

the

station

is

locked

in,andtheredLED

abovethatpresetswitchwilllight

up.

Programmed

tuning

is

possibleregardless

ofthe

MANUAL/AUTO

switchpostion.

It

mighthavecrossedyourmind,

but

whathappens

to

stationsyou've

programmedafter

the

TX-11

bis

switched

off?

Programmedstations

remainstored

inthe

memorysystem,evenwith

the

tunerunplugged

for

upto

threeweeks.

We've

alsoincluded

a

handystation

logto

writedown

the

frequencies

and

callletters

ofthe

stations

and

programsources

(onthe

lastpage

of

the

Appendix).Yes,it'spossible

to

fill

upall

13

stationpresets

on

the

TX-11

b.

Oftenwithstationsyou'veignored

inthe

past

dueto

annoying

noise

or

poorqualityreception.Since

13

stations

canbea

lotfor

anyone

to

memorize,just

jotthe

informationdown

inthelog

for

futurereference.

SignalStrengthIndicators

The

SIGNAL

indicators

show

youthe

strength

of

the

signal

the

TX-11

b

is

receiving.

Tothe

left

ofthe

frequencydisplay,

the

SIGNAL

indicators

are

arranged

in

10

dB

stepsfrom

20dBto80dB.The

higher

the

reading

onthe

indicators,

the

stronger

the

signalbeingreceived.

Locked

Indicator

The

LOCKEDindicatorlightswhen

the

tuningcircuit

has

locked

preciselyonto

the

frequency

ofthe

station

you'vetuned.

StereoIndicator

This

indicatorlightswhen

the

TX-11

b is

receiving

the

19

kHz

pilot

of

a

stereo

multiplexed

signal

forFM,orthe25Hz

pilot

for

stereo

AM.If

the

STEREOindicatordoes

not

light,

yetthe

station

is

positively

lockedwith

a

strongsignal,

itmaybethe

station

is

mono.

IF

Band

This

switch

controls

theIF

filter

circuit

the

TX-11b

uses.

It's

useful

when

stations

are

closeenoughtogether

onthe

band

to

startcausing

interference.

Push

in

(NARROW)thiscontrol

to

decrease

theIF

bandwidth

whenyou're

trying

to

tune

a

station,

andgeta

nearbysta-

tioncausingthistype

of

problem.

If

crowdedairwavesaren't

a

problem

in

yourreceptionarea,

you

shouldhave

the

control

off

(WIDE)

toget

improveddynamicrange.

TheIF

switchworks

in

both

AMandFM

bands.

When

switching

from

oneIF

mode

tothe

other,

the

TX-11

b's

muting

system

will

be

engagedbriefly,approximately

11/2

seconds.

AM

De-emphasis

This

AM

stereotuner

is

absolutelyunique

in

that

it

possesses

performance

capabilitythat

is

similar

tothe

performancecapability

of

anFM

tuner.

Ithas

bandwidththatextends

to

15

kHzandallits

other

specifications

are

verysimilar

toFM

specifications.Thisradio

hasthe

capability

of

soundinglike

anFM

set.

Asyoumayormaynot

be

aware,

FM

receivershave

a

deemphasiscurvethat

is

expressed

in

microseconds.

The

emphasis

forFMis75

microseconds.This

AM

radioalso

hasa

deemphasis

curve

that

allows

noise

free

high

fidelity

listening.Thisswitchshould

be

engaged,pushed

IN.The

reasonthat

there

isa

switch

onthe

frontpanel

is

that

notallAM

stations

usea

deemphasiscurvebecause

AM

stereo

is

fairlynew.

However,

we

havefoundthateverysingle

AM

station

inthe

Seattle

areadoes

indeed

usea

preamphasis

curvethatrequires

theuseof

a

deemphasiscurve.

The

switchshouldalways

beintheIN

position

for

normaluse.You'llnoticethat

it

comesfrom

the

factorytaped

IN.

We

have

been

unable

to

find

a

single

case

in

which

the

buttonshould

be

OUTbutwe

knowthattheoretically,somewhere

inthe

country,

there

isa

radiostationthatprobablydoes

notusea

preemphasis

curve

for

broadcasting.

Ifthe

button

is

left

out

while

you

listen

toa

radio

stationwithpreemphasis,

it

willsoundmuch

too

bright

and

much

too

noisy.

The

frequencyresponse

of

this

AM

tuner

is

flat

frombelow

20Hzto

15

kHz,

the

samespecificationsthat

anFM

systemhas.Using

the

deemphasisswitchallowsapproximately

a

10dB

increase

in

signal

to

noiseover

the

signal

to

noisethat

we

wouldobtainwithout

a

deemphasisswitch.That's

the

samereason

FMhasit,and

almost

everything

has

deemphasis

and

preamphasis.Cartridgeshave

it-

it's

called

theRIM

curve.

FMhasit;

it's

called

75

microsecond,

CD

playershave

it;

that

is

why

we

have

included

it- to

give

the

TX-11

b

bestpossiblefidelity.

10

RFGain

+12dB(AM)

Pushthisswitch

into

increase

the

sensitivity

forAM

stationsthat

are

veryweakand/orvery

far

away.

The

proper

operating

position

for

thisswitch

is

pushed

inand

leftthat

way,

justlike

the

noise

reduction

button

is

supposed

tobe

pushed

in

and

leftthat

wayfor

normaluse.

On

this

unit,

RF

gain

plus

12dB

button

andthe

noise

reduction

button

areoneinthe

same

andare

automatically

switchedfrom

AMtoFM

depending

on

whether

you

listen

toAMorFM.For

bothnoisereduction

FMandRF

gain

forAM

youare

supposed

to

leavethisbuttonpushed

inallthe

time.

For

AM,ifyou

have

an

overloadcondition,

or

hear

two

stations,

one

on

topofthe

other

indicating

an

overload,thenrelease

theRF

gain

switch

and

this

will

always

eliminate

the

offendingoverload

andit

will

usually

eliminate

thetwo

stations

ontopofone

another.

Ifit

doesnot,

then

you

have

to

push

intheIF

widenarrowswitch

to

reduce

theIF

response

oftheAM

receiver

and

thiswilleliminatethisproblem

of

two

stations

ontopof

one.

NoiseLimiter(AM)

Pushthisswitch

to

engage

the

impulsenoiselimiter

forAM

stations.

Thiscircuitwilleliminate

periodic,

low

dutycycleinterference,such

as

thatcaused

by

fluorescentlights,thermostats,lightdimmers,

and

soon.

Pushingthisbuttonengages

an

impulsenoiselimiter

forAM

stations.

Thisswitch

is

veryeffective

for

reducing

and

virtuallyeliminating

impulsetypenoisesassociatedwith

AM

reception.

It

worksbest

on

impulsenoisesthat

are

locallygenerated.

The

normalposition

for

thisbutton

isintheOUT

Position.Thisbuttondoesdualdutyalong

with

the

multipathreduction

onFM,

which

is

alsosupposed

tobein

theOUT

position.

The

normalposition

for

thisbutton

isOUTforAM

andFM.

NoiseReduction(FM)

Push

thisswitch

to

engage

the

noisereductionpart

ofthe

AsymmetricalCharge-Coupled

FM

Detector™*.

Use

thisswitch

gently,pushing

it

carefully

inthe

center.

Multipath

Reduction

(FM)

Pushthisswitch

to

activate

the

multipathreductionportion

ofthe

AsymmetricalCharge-Coupled

FM

Detector.

Using

the

Noise

and

MultipathReduction

Switches

The

followingsectionsprovideinformation

on

using

the

NOISE

and

MULTIPATHREDUCTIONswitches,

andthe

AsymmetricalCharge-

Coupled

FM

Detectorcircuit.

The

circuityourCarver

TX-11

b

uses

togetyou

morelistenablestereo

thanyou'veeverheardbefore

isthe

AsymmetricalCharge-Coupled

FM

Detector™.

The

first

part

of

thispatentedcircuit

isa

charge-

coupleddelayline

for

detecting

and

reducingphasemodulation

in

an

oncoming

signal.

Thisphasedistortion

is

multipath-induced,

and

canbe

compared

tothe

ghosts

yousee

when

theTV

signals

suffer

from

it.

The

secondportion

ofthe

circuit

isthe

LeadingEdgeDetector,

anotherbreakthroughderivedfrom

Bob

Carver'sear/brainresearch

(the

source

of

Sonic

Holography™,

too).

He

foundthat

allthe

noise-

polluted

L-R

part

oftheFM

stereosignalisn'tnecessary

to

makeyour

senseshearstereo.Whenthispart

ofthe

AsymmetricalCharge-

Coupled

FM

Detector

is

engaged,

the

TX-11

b

usesonlyenough

of

the

L-R

signal

to

producestereomusic

and

programming,rejecting

the

rest.

Although

the

AsymmetricalCharge-Coupled

FM

Detectorcan'thelp

noisy

and

distorted

L+R

components

ofa

transmitted

FM

stereo

signal,

itcanaddupto23dBof

signal-to-noiseratio(S/N),

and

make

stereosignals

as

quiet

as

stationsbroadcast

in

mono.

To

further

understand

howthe

AsymmetricalCharge-Coupled

FM

Detector

and

variouscomponents

ofthe

transmitted

FM

signalinterrelate,

see

Section

1ofthe

Appendix.

In

FM

mode,

the

lower

twoofthe

fourswitches

(onthe

lowerright-

hand

side

ofthe

TX-11

b)

engage

the

Asymmetrical

Charge-Coupled

Detector.

The

lower

left

switchengages

the

noisereductioncircuitry;

the

lowerright,

the

multipathreductioncircuitry.Eitherone,

or

both

may

be

engagedsimultaneously.

Pushing

just

the

MULTIPATHREDUCTIONswitchsets

the

circuit

to

reducemultipath

and

noise

by

approximately

15dB,and

optimizes

the

circuit

for

multipathreduction.Pressing

the

NOISEREDUCTION

switch

sets

the

circuit

to

reducenoise

and

multipath

by

approximately

10

dB.The

NOISEREDUCTIONswitchwilloptimize

the

circuit

for

reducingnoise.

If

bothswitches

are

engaged,therewill

be

approximately

23dBof

noise

and

multipathreduction

for

received

signalstrengthlevelsbetween

1

p,V

and20

(j,V.

In

otherwords,very

weak

or

distantstations.

Which

switch

youuse

depends

onthe

problemswithreception.Some

stations

willsoundbest

ifthe

NOISEREDUCTION

is

engaged;

some

withonly

the

MULTIPATHREDUCTIONswitched

in;

somewithboth.

It'simportant

to

rememberthatmoststereoreceptionproblems

can

be

cleared

upby

using

the

MULTIPATHREDUCTIONpart

ofthe

circuit

by

itself.

At

least

until

you've

hada

chance

to

set-up

an

antenna

system

and

experiment

ona

station-by-stationbasis,

we

suggest

switching

the

MULTIPATHREDUCTION

inand

leave

it

thatway.

This

willresult

in

spectacular

FM

stereoreception

ina

greatmanyareas,

andforthe

majority

of

stations.However,

ifa

station

suffers

fromboth

noise

and

distortion,plus

is

veryweak,

usethe

NOISEREDUCTION,

too.

If

your

TX-11

b

will

be

usedwith

a

commercialcable

FM

feed,

it

will

probably

be

enough

touse

just

the

NOISEREDUCTION.

Multipath

interference

isnot

really

an

issuewithcablereception.

If

you're

connected

to

cable,

we

suggest

the

NOISEREDUCTION

be

simply

11

switched

in,and

left

in.

This

can

give

you

music

and

programming

that'sunbelivablyclean

and

quiet,without

a

hint

of

annoyingdistortion

and

noise.With

the

noisereductionfeatures

ofthe

Asymmetrical

Charge-Coupled

FM

Detector,

FM

stereolistening

on

cablefeed,

in

many

cases,

will

rival

or

exceed

the

noiseperformance

of

yourtapes

(cassettes,reel-to-reel,etc.),

in

terms

of

audio

quality.

MutingTime

When

either

the

NOISEREDUCTION

or

MULT1PATH

REDUCTION

switches

are

engaged,

a

logic

systemanalyzes

the

signal

for

multipathand/ornoisecontent.Thisprocessrequiresabout

3/4

ofa

second.Whenever

a new

stationselection

is

made,

the

mutetime

is

about

1/2

second.

Ifa new

station

is

selected

AND

either

the

NOISE

REDUCTION

or

MULTIPATHREDUCTIONswitch

is

simultaneously

engaged

ORhas

alreadybeenengaged,

the

mutingtimes

are

additive:

3A

+

1/2

=

11/4

seconds.

Antennas

Sendinginformationthrough

the

air,

as

part

of

basic

radio

broadcasting,

isa

relativelysimpleprocess.

At

the

broadcaster'send,

the

set-upincludes

a

studio,

transmitter,

and

transmittingantenna.

The

studiosuppliesprogrammaterials(music,drama,news,etc.)

to

the

transmitter.Acting

asa

giantamplifier

of

sorts,

the

transmitter

sends

the

signal

at

highpower

anda

specificfrequency

ontothe

transmittingantenna

inthe

form

of

alternating

current.

This

creates

an

electromagenticfieldthatpropagatesthrough

the

air.

At

yourend,

the

listener'send,

a

length

of

wire

issetupforuseasa

receiving

antenna.When

the

electromagnetic

fieid

generated

bythe

transmitter/transmittingantennacombinationreaches

the

wire,

a

small

AC

current

is

induced

init.A

tunerconnected

to

thiswire,

or

receivingantenna,translatesthissmallcurrentbackinto

a

"usable"

form.

In

short,backintomusic,drama,

and

otherprograms

for

your

enjoyment.

Of

course,

this

description

of

whatgoes

oninthe

transmissionpart

of

radiobroadcasting

has

beengreatly

over-simplified.

There's

alot

going

oninthe

actualtransmission

of

stereosignals,

and

you'llsoon

discover

there's

a lot

going

onat

your

end

when

it

comes

to

that

"length

of

wire"

or

receivingantenna.Thischapter

isan

in-depth

discussion

ofhowyoucan

obtain

the

bestsignalpossible

fortheTX-

11

b

throughselection

and

installation

ofan

antennasystem.

Atthe

same

time,

we

offer

somealternatives

and

ideas,

soyoucan

choose

a

systemthat's

not

onlyright

forthe

TX-11

b,but

right

foryouand

your

locale.

We'll

be

looking

atthe

threemajortopicsthatconcernreceiving

antennas:antennaconfigurations,

installing

the

antenna,

andthe

feedlinefrom

the

antenna

tothe

TX-11

b.Of

course,

if

you'vedecided

to

have

a

companydistribute

TVandFM

programming

to

yourhome

via

cable,

the

followinginformation

maybeof

passinginterestonly.

Skip

ahead

tothe

CABLEsection

attheendof

thischapter.

If

you'd

like

to

knowmoreaboutantennas,

the

benefits

ofa

qualityantenna,

and

some

ofthe

causes

and

cures

for

multipath,pleaseread

on!

FM

Antennas

Configurations

To

beginthislook

at

receivingantennas,

we

mustfirstestablish

a

reference

for

comparing

different

antennas.

Our

reference

antenna

will

bea

half-wavedipole,justlike

theone

thatcamewith

the

TX-11

b.

Antenna

A isan

illustration

of

thistype

of

ribbondipoleantenna.

Notice

the

length

ofthe

"arm"

or

element.This

is

importantbecause

antennas

are

resonant(electricallysensitive)whentheirlength

is

one-

half

the

wavelength

ofthe

transmitted

signal.

Here's

the

formula:

5616

divided

bythe

frequency

in

megahertz(MHz)

=

half

a

wavelength.

The

middle

oftheFM

band

is98

MHz,

so

57.3"

is

half

a

wavelength.

As

youcan

guess,

this

iswhy

it's

called

a

half-wave

dipole.

Another

antennacharacteristic

isits

gain.

Thisresults

from

a

focusing

of

the

electromagnetic

energy

ofa

transmitted

signal.

The

half-wave

dipolethatcamewith

the

TX-11

bis

bi-directional.

Ifyou

werelooking

down

onthe

dipolefromabove,

the

receptionpatternwouldappear

asit

does

inthe

diagram

of

Antenna

A.

reception

pattern

52"

to

63.7"

configuration

Now

that

you

know

the

importantcharacteristics

ofthe

reference

dipoleantenna,let'slook

ata

commonderivative,

the

Yagi

(or

Yagi-

Uda,

morecorrectly.

It's

named

forthe

folks

who

invented

it).

The

Yagi-typeantenna

is

Antenna

Binthe

diagram.These

are

multielementantennaswhere

the

drivenelement,

the

partthat's

connected

tothe

feedline,

is

surrounded

by

reflectorsbehind

it,

directors

in

front.Look

atthe

receptionpattern

inour

diagram.Note

the

dramaticchange

in

directionalityfromthat

ofthe

dipole.

The

gain

of

a

Yagi-typeantennadepends

onthe

number

of

elements,their

lengths,

and

spacings.

But

compared

tothe

reference

half-wave

dipole(where

the

gainequals

"0

dB",)

Antenna

Bhasa

greatergain:

from

6dBto20dB—all

otherthingsbeing

equal.

receptionpattern

12

The

practical

consequences

of

changes

in

gain

and

directionality

are

several.First

of

all,

while

the

referencedipolewillusuallydeliver

enoughsignals

for

goodreception,

is

"good"goodenough?Consider

that

the

19

kHz

pilot

signal

the

tuneruses

to

sense

a

stereobroadcast

is

transmitted

at

1/1

Oth

the

power

ofthe

signalcarrier.

If

thispilot

signal

is

lost,stereogoesaway.

Ifthe

pilotsignal

is

degraded,

so

will

be

the

stereoseparationbetween

the

left

and

rightchannels.

A

strong

signal

is

alsonecessary

to

reducenoise:noiseassociatedwithsignal

transmission,

and

noisefrom

localized

sources

of

interference.

Directionality

can

alsoreduce

the

strength

of

signalscoming

in

from

elsewhere.Thisincludesother

FM

stations,multipathreflectionsfrom

the

stationyou'relistening

to,

even

the

blender

inthe

kitchen.

Installations

Thissubject

is

prettystraightforward.

Allyou

reallyneed

to

know

is

that

the

higher

the

antenna,

the

better.

Height

is

important

because

radiowavestravel

ina

straightline,

or

line-of-sight.

If

yourantenna

is

free

and

clear

of

obstruction,

it

willperformbetter,

and

you'llgain

signal

strength.

Height

is

alsoimportantbecauseradiowavesbounce.Theybounce

off

hills,

buildings,

even

offthe

ground

in

front

of

your

antenna.

When

a

bouncedwavegets

to

yourantenna,

ithas

travelled

a

slightlylonger

paththan

the

line-of-sightwave,gettingthereslightlylater.

The

result

is

phase

distortion,

usually

the

loss

of

stereo

reception,

in

other

words:

the

dreadedmultipath.

The

higher

the

antennafrom

the

ground,

the

lesssusceptible

itisto

other

interference,

as

well.

A

roof-mountedantenna

is

muchlesslikely

to

"hear"vehicleignitionnoisefrom

the

street,

or

inducedinterference

within

the

home:

from

vacuumcleaners

tothe

kitchenblender.

Feedlines

canbe

compared,

ina

way,

tothe

cablesthatinterconnect

the

differentcomponents

in

yourstereosystem.

If

thesecables

and

cords

areof

poorquality

or

condition,perhapspoorlyinstalled,even

the

bestaudiocomponentswill

not

sound

as

good

as

theyshould.

It's

the

samewithantennafeedlines.

Youcan

cancel

any

advantage

from

height,

or

from

having

a

multielement,high-gainantenna

ifthe

connectionsbetween

the

antenna

and

tuneraren'tright.

Thetwo

commonfeedlinechoices

are300ft

twinlead

(alsoknown

as"TV

antennawire"),

and

7511

coaxialcable.There

are

sometrade-offs

whendecidingwhich

feedline

is

best

touse

withyourantenna

system.

300ohm

TWINLEAD

The

majoradvantage

to300ft

twinlead

is

thatit'sinexpensive,

and

if

it's

properlyinstalled,signallosseswithin

itare

reasonable(about

1.25

dBper

100

feet

at

100

MHz).However,

ifthe

twinlead

is

poorly

installed,

itcanact

like

an

antennaitself,degrading

the

performance

of

the

rest

of

yourset-up

by

picking

up

extraunwantedsignals,

and

interferencenoise.Twinleadrequirescarefulrouting,

and

must

be

insulatedfromeverythingmade

of

metal,likegutters,otherwires,

etc.Plus,

ifit

rains

in

your

neighborhood

like

it

does

in

ours,signal

losses

gowayup

with

wet

twinlead.

75ohm

COAXIALCABLE

Compared

to

averagetwinlead,

75ft

coaxialcable

is

moreexpensive,

and

it's

a bit

harder

for

signals

toget

throughcoax(about

3.5dB

loss

per

100

feet

at

100

MHz).

The

75ft

impedence

ofthe

cablemeans

a

matchingtransformerwillhave

tobe

installed

atthe

antenna(not

atthe

TX-11

b;ithasa75ft

connector

onthe

rearpanel).

The

realadvantages

to

coaxialcable

are

that

it's

not

prone

to

pick

up

extra

noise

and

interferencebecause

it's

shielded,

and

doesn'tsuffer

much

inwet

weather.Also,

you

don'thave

tobeas

carefulabout

routing,

so

installingcoax

is

mucheasier.

Antenna

Choices

As

we'vesaid,dipoleantennastend

tobe

susceptible

to

noise

because

they

aren't

very

directional,

and

because

they're

usually

mountedinside

the

home.Depending

on

yourspecificarea

and

location,signalstrengthwill

be

adequate

at

best.This

isduetothe

lack

of

directionality

and,

in

most

cases,

height

ofthe

antenna.

But

there

are

someadvantages,including

low

cost.

Inall

fairness,

the

type

of

dipoleantenna

we

providedwillwork

well

in

manydifferent

places

and

situations.

It

should

at

least

be

used

soyoucan

start

enjoying

FM

programmingrightaway,beforesettling

on

another

antennasystem

or

commercialcable.

It

should

be

pointed

out

that

the

ribbondipoleantennathatcame

with

your

tunerisn't

the

onlystyle

of

dipoleantenna.There

are

other

dipoleswhich

you

installoutdoors.Thesedipoles

can

overcomesome

of

the

problemswhichnormallymake

the

dipole

a

mediocreantenna

choice.

RABBIT

EARS

Unfortunately,

rabbit

ear

antennas

have

the

same

disadvantages

of

the

half-wavedipole.

Onthe

otherhand,rabbitears

canbe

tuned

by

adjusting

the

"ears"

tothe

wavelengths

ofthe

stations

you

listen

to.

Remember,

a

halfwavelength

atthe

bottom

endoftheFM

band

is

63.7";

atthe

upperend,it's52".

Youcan

easilydetermine

the

right

length

of

each"ear"needed

fora

particularstation.Also,

the

orientation

of

rabbit

ears

is

easy

to

change,

unlike

the

dipole

which

is

usuallystuck

toa

wallsomewhere.Movingrabbitearsaround

is

simple.Changingantennasfrom

one

wall

to

another

will

work,

but

thatisn't

the

whole

story.

Rabbit

ear

antennashave

one

more

disadvantage:

notas

muchgain

asthe

dipole.Also,check

toseeif

the

rabbitearshave

a FM

trap

to

removepossible

TV

interference.

All

thingsconsidered,rabbitearswillprobably

doa

better

job

than

the

half-wavedipoleincludedwithyourtuner.

INDOOR

FM

ANTENNAS

There

area

number

of

"blackbox"

or

table-top

FM

antennasavailable.

They'reessentiallyrabbitears:

youcan

tunethem

for

particularparts

of

theFM

band;

youcan

changetheirorientation(electrically).Losses

in

gain

are

about

the

same

as

rabbitears,

in

comparison

tothe

reference

dipoleantenna.

13

TV

ANTENNAS

If

a TV

antenna

is

mountedhighenough

and

connectedwith

a

properly

installedfeedline,

it

shouldresult

in

moreavailablesignal

than

the

antennaswe'vetalkedabout

so

far.Perhaps

notas

much

signal

asa

directional

FM

antennabecause

TV

antennas

are

broadband

(54MHzto

216

MHzfora

VHP

model).However,some

TV

antennashave

special

provisions

for

receiving

FM

signals,

while

the

rest

ofthe

antenna

is

used

for

VHP

TV

reception.Thatcould

be

more

moneythanyou'dwant

to

spend,unlessyou'reusing

the

antenna

for

both

TVandFM

reception.

If

you

alreadypossess

a TV

antenna,

orare

planning

to

hook

uptoa

master

antennasystem

inan

apartmentbuilding

or

condo,

it

might

not

work.Some

TV

antennashave

anFM

filter

built-in

to

rejectexactly

the

samesignals

you

want

to

hear.

Ifyou

fallinto

the

group

of

people

who

alreadyhave

TV

antennasinstalled

in

theirhomes,there

are

still

some

things

youmay

want

todo

before

adding

a

splitter

to

supply

signals

forthe

TX-11

b.

You'veovercome

oneofthe

costs

inan

antennasystem

by

having

the

antenna,

but

possiblereinstallation

andnew

feedline

maybe

desirable,evennecessary,

for

proper

performance.

It

willprobablyalsorequirereaiming

the

antenna.That

couldcreatesomeproblemswhichcoulddegrade

theTV

reception.

Thismeansyou'dhave

to

install

an

antennarotator.

A

rotator

allows

almost

infinite

realignment

ofthe

antenna

to

produce

the

best

signal

possible

for

stations

you

want

to

hear(andsee)

ona

station-to-station

basis.

OUTDOOR

FM

ANTENNAS

When

mounted

and

connectedproperly,

a

directionaloutdoor

FM

antenna

can

provide

the

bestsignal

of

all,with

the

lowestinterference

and

noisefactor.

The

greatestdisadvantage

to

thissystem

isthe

cost

of

the

antenna,

mounting

hardware,

anda

rotator.

The

rotator

isan

absolutenecessity

ifyou

want

to

pointthesehighlydirectional

antennas

in

morethan

one

direction.Most

FM

antennas

of

thistype

tend

tobe

evenmoredirectionalthan

a lotofVHFTV

antennas,with

or

withoutspecialprovision

forFM

reception.

Inany

outdoor

installation,

the

cost

ofa

groundrod,feedline,

and

insulatorsmust

also

be

figuredinto

the

totalprice

ofthe

antennaset-up.

The

combined

totals

can

quickly

addup.

Otherthandirectional

FM

antennas,there

are

outdoordipole

antennas

that

can

provide

many

ofthe

same

benefits,

ata

somewhat

lower

cost.You'realreadyfamiliarwith

the

half-wavedipolewhich

can

also

be

calledsingledipoleantennas.

The

dipolethatcamewith

the

TX-11

b is

meant

tobe

usedindoors,

andhas

justthat

one

upper

arm,

or

element.

The

virstvariation

on

this

dipole

isan

antennathat

is

really

two

singledipoles

setat

rightangles.

It

works

the

same

way

as

the

single

dipole

but

instead

of

picking

upthe

majority

of

signals

in

two

directions,

the

dual

dipole

will

pick

up

signals

ina

modifiedomni-

directionalpattern.

Another

outdoor

variation

isthe

S-curve

omni-directional

antenna.

For

all

intents

and

purposes,

the

S-curveantenna

is

just

a

single

dipolebentinto

a

"S"

shape.

The

change

inthe

shape

ofthe

antenna

makes

its

pick-uppattern

a

littlemoreomni-directionalthan

the

reference

dipole.

Other

than

the

changes

in

pick-up

patterns,

both

thesemodifieddipoles

offer

moregainthan

the

reference

dipole.

On

topof

that,theseantennas

maybe

installedhighenough

to

reduce

the

possibility

of

localinterference,

and

some

multipath

interference

problems.

When

totalling

up

costs

for

hardware,these

two

outdoordipoles

eliminate

the

need

ofa

rotator,

but

will

still

require

the

proper

mounting

hardware

and

feedlines.

You

mustweigh

and

compare

the

costs

and

benefits

of

directional

vs.

omni-directionalantennasystemsinstalled

outdoors

onthe

results.

It

could

bethe

omni-directionals

willgive

superiorcoverage

and

signalquality

in

yourarea,making

a

directional

antennaunnecessary.

Onthe

otherhand,

the

directional

FM

antenna

may

bethe

onlyroute

togo

because

of

severelocalizednoise

and

multipathinterferenceproblems.

The

point

is

thatactualantenna

selection,over

and

above

the

fact

someantennas

are

"better"than

others,must

be

made

onan

area-by-areabasis.Terrain,transmitter

locations,

and

your

relation

to

them

will

bethe

deciding

factorswhen

figuring

out

whichsystemwillreceive

the

signals

the

best.

Installation

Choices

INDOORINSTALLATION

For

obviousreasons,indoorinstallations

arethe

easiest

todo.It

doesn't

involvemuch

to

stick

the

dipolethatcamewith

the

TX-11

b

on

a

wall.

But

remembersome

ofthe

drawbacks

to

indoor

antennas:

1)

height,

and2)

possibleproblemswithinterferencefromcars

on

the

street

and

smallelectrics

inthe

kitchen.Plus,antennaheight

is

essential

to

goodsignalstrength

and

signal-to-noiseratio.

An

indoorantenna

can

work

justfine

if

you're

ina

taller

building

with

good

"line-of-sight"

tothe

area's

FM

transmittingtowers,

or

other

places

where

youget

clean

signals

fromyourfavorite

stations.

If

you'vebeenlistening

toFMon

anotherreceiver

in

yourhome,

you

might

geta

veryroughidea

how

manystationscould

be

available.

However,

your

TX-11

b isa

tunerwithimpeccableperformance,

capable

of

makingstationsthatweretotallyobnoxious

dueto

noise

and

distortion,soundgreat!Thisalonewillallow

youto

experience

allthe

pleasure

ofFM

stereolistening,with

a

less-than-ultimate

antenna.

Ifyou

can't

geta

trulylistenablesignalfrom

a

dipole

or

other

type

of

indoorantenna,there

are

otheroptions.

OUTDOORINSTALLATIONS

Properly

done,outdoorinstallations

can

offer

vastly

improvedsignal

quality

over

indoorantennas.

But

there

isthe

cost,

andthe

actual

effort

of

putting

itallup.

Another,perhapsmostimportantconsideration,

is

SAFETY.Safety

is

veryimportant

in

planning,

setting-up,

and

using

your

antennasystem.Withthat

in

mind:

•

Don't

runthe

risk

of

having

a

bolt

of

lightning

—

natural

orman

made

—join

you,your

tuner,

and

yourstereosystem

inthe

living

room:

A)

Keep

the

antenna,mast,boom,

guy

wires,feedline,whatever

away

from

all

powerlines.Thatincludes

the

linesfrom

the

powerpole

tothe

house.DON'TEVENTHINKABOUTPUTTING

ITUP

WHERE

r

14

IT

COULD

FALL

INTO

POWER

LINES!

B)

Make

sure

the

antenna,

mast,

and

boom

are

properly

grounded

with

a

largeconductor-wire

running

from

the

antenna

toa

ground

rodinas

short

a

path

as

possible.

NOTE:

10-gauge

copper,8-gaugealuminum,

or

12-gauge

copper-

cladsteelwireshould

dothe

job.However,

the

heavier

the

better.

Certainmasts

canbe

grounded

bya bar

attachment

toa

groundrod,

with

a

strap

asa

connector.

This

isa

superiorgroundattachment

if

the

mast'sbaserests

onthe

ground,

or

specialgroundplate.

•Use

stand

off

insulators

to

keep

the

groundwireawayfrom

the

house.Spacetheseinsulatorsfour

tosix

feet

apartwherepractical.

It's

a

poorpractice

to

staple

the

wire

to

yourhouse.

•Usea

proper

antenna

discharge

unit

or

lightening

arrester,

mounted

as

close

as

possible

to

where

the

feedlineenters

the

house.Make

sure

the

arrestor/dischargeunit

is

securely

attached

tothe

ground

rod

with

the

heavy-gaugegroundingwire,insulatedwithstand

off

insulators

along

the

house.

•

NEVERground

the

antenna

(or

anything)

toagas

pipe.

Makesure

any

groundingschemeemploying

pipes

inthe

house

belong

tothe

water

system.

A

lightening

strike,instead

of

being

harmlesslyrouted

to

earth,

can

turnyourhomeinto

an

explodingsun.

•If

yourantenna

and

mastrequire

the

support

ofguy

wires,makesure

the

wires

use

in-line

insulatorsbetween

theguy

wire

and

roof.These

insulatorselectricallyisolate

the

supportwiresfrom

the

house.This

isn't

a bad

idea

even

iftheguy

wires

are

anchored

tothe

earth.

•

NEVER,

NEVER

work

onany

part

of

(andbestkeepcompletelyaway

from)

yourantennasystemduring

an

electricalstorm!Remember

to

disconnectyour

TX-11

b

from

the

antennaduringelectricalstorms,

too.

•

Anotherimportantitemrelated

to

personal

safety

is,of

course,

to

be

careful

when/if

you

startclimbingaround

on

roofs

andthe

like.

Don'tmakeyourantennainstallation

bethesetupfora

quickfall.

Ground

Rod

When

it

comes

tothe

ground

rod

we've

beentalkingabout,thismetal

rod

should

be

drivendeeplyinto

the

earth.

A

ground

rod

drivenonly

two

feetdownusually

has

three

to

fourtimes

the

resistance

ofa

ground

rod

driven

ten

feetdeep.That's

the

key:

low

resistance.

The

object

ofall

thisgrounding

isto

give

a

lighteningstrike

the

easiest

path

tothe

earth,

not

your

home.

Aswe

said,makesure

youusea

lightening

arrester

or

dischargeunitthat'sattached

tothe

ground

rod

with

the

sameheavy-gaugewireusedfrom

the

antenna

tothe

discharge

unit.

BetweenAntenna

and

Tuner:Feedlines

Last

butnot

least

in

considerations

for

putting

upan

outdoorantenna

is

the

feedlinewhich"connects"

itall

together.Earlier

inthe

chapter,

we

talked

about

the

problems

and

merits

of300

0

twinlead

and75(1

coaxialcable.There

are

some

additional

thingsthatcouldrelate

to

your

finalchoicebetween

the

two.

300

0

TWINLEAD:Remember,it'slessexpensive

andhasthe

lowest

line

losseswhendry,

and

properlyinsulatedfrom

the

house

and

mast

withstand

off

insulators

specially

designed

for

twinlead.Twinlead

mustalso

be

kept

away

frommetalgutters,windowframes

and

other

wires.

Of

course,

it

should

be

keptwellawayfrom

power

lead

ins.

Thereshould

be

over

an

inchspacingbetweenotherwires

inthe

home

and

stereosystem

—

more

is

better.Avoiding

the

obstacles

we've

mentionedwill

add

overalllength

tothe

lead

in,and

some

of

thesedetourswillcause

additional

line

losseswhenwet.Also

rememberthattwinleadmust

be

wellinsulatedfrom

the

antennamast,

house,etc.withstand

off

insulators.Theseinsulators

are

available

ina

variety

of

attachments:

the

shaftscometerminated

in

screw-in

units,masonrynails

for

brick

and

concrete,

and

nail-ins

to

suit

any

installationneed.

The

stand

offs

should

be

usedabouteveryfourfeet

with

twinlead.

In

addition,

special

careshould

be

takenwhenrunning

twinleadthrough

a

wall,

or

bringing

it

indoorsthrough

a

window

frame.

Use

a

walltube

or

framebushing

to

isolate

and

insulate

the

twinlead

from

the

wall/framematerials.This

can

avoidpossiblesignalloss

and

interferenceproblems

at

thispoint

inthe

installation.

Ifthe

total

run

from

the

antenna

to

your

TX-11

b

exceeds

300

feet,

a

preamp

atthe

antennamight

be

needed

to

boostsignals

inthe

line.

75

n

COAXIAL

CABLE:

Coaxialcable

isthe

easiest

ofthetwo

feedlinechoices

to

install,

andhas

somedistinctadvantages.

Obstaclesthatwouldseriously

affect

the

performance

of

twinlead

canbe

virtuallyignored,

and

since

coaxialcable

is

shielded,

interference

is

muchless

ofa

problem.

The

onlyrealdrawback

isthe

cost,

andthe

need

ofa

preamp

to

boostsignal

in

runsover

120

feet.

Actually,

120

feet

isa

prettylong

way

fromyourantenna

tothe

tuner.

Also,

sincecoax

is

easier

to

install,

the

cost

of

cable

and

preamp

(if

needed)

canbe

made

upina

moreeffortlessinstallation.Plus,

the

benefits

of

loweredlosseswhenwet,

and

reducedinterference

can

be

an

additional

incentive

touse

coaxialcable.Coaxialcable

canbe

easilybroughtinto

the

house

tothe

tunerwithout

the

need

of

special

fittings

or

passages.

Fewer

stand

off

insulators

canbe

used

inan

installation

usingcoaxialcable

asa

feedline:

one

aboutevery

sixto

eight

feet.

SomeAdditionalHints

•

Ifyou

decided

to

chimney-mount

the

antenna,

route

the

feedline

away

from

the

chimneyoutlet

byat

leastthreefeet.Heat,smoke,

and

residue

can

breakdown

the

insulation

of

bothtwinlead

and

coaxial

cable.

•

If

you'replanning

to

attachyourantennasystem

toa

chimney,make

sure

the

chimney

hasthe

structuralstrength

to

support

it.

Thoroughly

inspect

the

chimney

for

loosebricks,brokenmortar,cracks,

or

other

conditions

thatcouldindicate

a

poorstate

of

repair.

•DONOTusea

metalchimneystovepipe

to

support

an

antennaset-

up.

Otherthan

the

considerations

of

structuralsupport,

a

lightening

strike

could

turnyourstoveinto

a

giantelectrode.That

can

happen

with

a

metalpipechimney,even

ifthe

antennaitself

has

beenproperly

grounded.

•For

those

whoare

located

a

considerabledistancefrom

anyFM

transmitting

facility,

a

tower

or

mast

maybe

necessary

to

obtain

better

line-of-sight

and

clearance

forthe

antenna.

If

youroutdoor

installation

fits

intothiscategory,

pre-made

masts

and

towerkits

are

available

from

many

TV

stores

and

electronic

supply

shops.Despite

the

cost,

a

30-to-50

foot

mast

or

tower,

in

combinationwith

a

good

high-gain

15

antenna,

can

provide

a

quality

signal

forthe

TX-11

b.

Even

in

"fringe

areas"

wheregoodreception

is

normally

a

realproblem.

Be

sure

any

mast

or

towerset-up

is

properlysecuredwith

guy

wiresupports

(if

needed),

and

installedwhere

it

can'tfallintopowerlines,

the

neighbor'sgreenhouse,

or

whatever.

Cable

When

we

talkaboutcable,

we

mean

a

masterantennasystem

supplying

high

quality

TVand

FM

signals

to

individual

homes

(or

"subscribers").

The

signals

are

sent

viaa

distributionnetwork

of

wires

and

lineamplifiers.

The

wire,

or

cableportion

ofthe

system,

canbe

likened

toa

telephonedistributionset-up.

The

lineamplifiers

are

used

to

boostsignals

at

certainintervals

inthe

lines,muchlikeusing

an

antenna

preampwithlongfeedlines

in

your

own

antennasystem.

Originally,

communitycabletelevision

(CATV)

wasa

response

tothe

problems

of

poor

or

nonexistantreception

ofTV

signalsbroadcast

"clear

air."Theseproblemscould

be

caused

by

distance,terrain,

or

even

just

remotelocations(out

of

range,

or

fringeareareception).

The

cablecompanychooses

a

highhilltop

or

otherlocationwhere

they

can

obtain

the

best

line-of-sight

tothe

area'stransmittingtowers.

Thissite

is

known

in

cableparlance

asthe

"headend."This

is

where

high-gain

antennas

and

amplifiers

are

used

to

receivedistant,weak,

or

otherwise

unreceivable

signals.

The

signals

are

passed

onto

line

transmitters,

then

tothe

distributionpart

ofthe

cablesystem.

At

yourhome,signalsfrom

the

cable

inthe

street

arefedto

your

TV

set.

Ifyou

want

FMas

well

asTV,the

signals

are

split

with

oneset

going

totheTV,the

other

to

your

TX-11

b.Of

course,

youcanbe

connected

to

justreceive

FM

signals,

without

the

videohook-up.

An

FM

feed

mayusea

specialfilter

to

remove

TV

interference,

orto

prevent

you

from

illegally

receiving

FM

signals

from

a

single

TV

feed,

an

FM

trapmight

be

installed

atthe

street.When

the

cablepeople

connectyour

TX-11

btothe

system,

any

necessary

filters

are

installed,

any

traps

are

removedfrom

the

line.Thisbrings

up

somethingelse

again:

it's

not

legal

totap

into,

or

hook

a

commercialcable

up

yourself.

It

must

be

done

bythe

cablecompany.

As

mentionedearler

in

thismanual,feedlines

for

cable

TVareall75fl

coaxialcable,

so

connections

canbe

madedirectly

tothe

TX-11

b's

75

ft

antennainput.However,

the

usualprocedure

isforthe

cable

companyinstaller

to

connect

a

tunerwith

a

matchingtransformer

(75

ftto300ft)toits300ft

inputs.

Aswe

suggested,

askthe

installer

if

it

would

be

possible

tousethe

TX-11

b's75ft

input.

The

benefits

of

using

a

commercialcable

to

supplyhighquality

FM

stereo

signals

forthe

TX-11

bare

many.

For

example,

you

don'thave

to

worry

about

the

cost

and

effort

of

installing

a

goodoutdoorantenna.

You

don'thave

to

worry

about

the

performance

of

such

a

system

after

all

thatwork,either.

Asa

rule,cablecompanieshave

a

one-time

installationcharge,then

a

monthlyfee.

The

cost

of

cableservice

can

depend

on

manyfactors,

and

variesfromsystem

to

system.Costs

will

run

higher

fora

commercial

cable

feed

for

both

TVandFM

service,

less

forFM

only.

Other

thanopening

upanew

world

for

enjoyment

ofFM

programming,

commercialcable

can

open

anew

world

of

audio

for

your

TV

set.Many

cable

systemsprogrampremiummovie/filmserviceswith

spectacular

stereo

soundtracks.

The

videoportion(withstandardaudiocarrier)

is

broadcast

onthe

cable

fortheTV

set.

A

separatestereosoundtrack

is

broadcast

intheFM

band.

The

TX-11

b

receivesthesesignals

and

turnsyour

living

room

into

a

real

theater

or

concert

hall.

Younot

only

see

greatartistsperformingyourfavoritemusic,

but

hear

it

like

you

werethere.Thisset-upfreesyour

TV

from

its

burden

of

having

a

tiny,

limited-response,internalaudio

ampand

speaker.

AM

Antennas

The

Motorola

CQUAM™

AM

stereosystemrequires

a

stronger

and

cleanersignal

to

takefulladvantage

ofthe

benefits

ofAM

stereo.

Two

AM

antennas

are

includedwithyour

TX-11

b:a

longwireantenna

and

a

loopantenna.

We

havedetailed

the

benefits

of

eachtype

to

help

you

select

the

bestantenna

for

yourenvironment.

AM

WireAntenna

The

longwireantenna

is,

undermostcircumstances,

the

preferred

antenna.

Itis

able

to

receivesignalsfromfartheraway

and

willreceive

normally

distantsignalsmuchstrongerthan

the

smallloopantenna.

Thiswireantenna

is

alsomoreeffective

for

eliminatingnoisesthat

occur

ininthe

atmospherethat

isata

distancefrom

the

tuner.

The

long

wire

orientation

isnot

particularlycritical.Sincethisantenna

is

used

for

maximumsensitivity,

ifyou

liveveryclose

toa

strong

transmitter

youmay

overload

the

front

endof

yourtunerwiththis

antenna

and

willwant

totrythe

loopantenna.

AM

LoopAntenna

There

are

certainconditions

in

which

the

loopantennaworksbest.

It

has

betternoiserejection

for

locallygeneratednoise

-

noisesthat

are

generatedclose

tothe

tuner

andmay

soundlikebuzzes

or

hum.

Itis

able

to

reducethesenoises

fortwo

reasons:

1)

Thisantenna

is

directional,

and2)ithasa

lowerdrivingimpedancethan

the

wire,

so

it

tends

to

short

circuit

this

kind

of

interference

readily.

The

loopantennapicks

upthe

signal

at

rightangle

toan

axispassed

through

the

loop.

Ifyou

want

to

pick

upa

radiostationthat

isdue

north,

orient

an

axisthatpassesthrough

the

loop

at

rightangles

to

north.

If

you

wereholdingthisantenna

asifit

were

a

gun,

you

wouldpoint

it

at

the

station.Again,

the

loopantenna

isfor

maximumrejection

of

locally

generated

interference.

Ultimate

AM

Antenna

For

those

ofyouwho

wouldlike

to

take

the

time

to

build

the

ultimate

AM

antenna,

we

offer

the

plansthatfollow.Thisantennaincorporates

the

benefits

of

both

the

wire

andthe

smallloop.

It

willhave

the

noise

reductioncapability

ofthe

smallloop

for

locally

generated

noise,

the

noise

reductioncapability

ofthe

wire

for

atmosphericallygenerated

noise,

it

will

be

extremely

sensitive,

andit

will

be

very

directional.

Thisantenna

is

basically

a

home-built

loop

whosearea

is

measured

in

squarefeetratherthansquareinches.

To

buildthisantenna:

1)

Construct

a

woodcrossframethatmeasures

12"

from

point

to

16

I

point.(17"

eachcrossbar).

2)

Secureframe

toa

base.

3)

Wrapframewithfour

turns

ofthe#22

insulated

solid

wire.

4)

Twistwireendstogetherapproximately

2

turns

per

inch.

5)

Stripwireends

1/2

inch

and

connect

toAM

terminals

on

back

of

TX-11b.

Drawing

A

shows

a

completedantenna.

Drawing

B

detailsconnections

forall3

antennas.Don't

be

afraid

to

experiment

to

discover

the

best

antenna

for

your

location.

_—

_

frame

— —

wire

loop

17"

base

B

SomeOtherThoughts

The

bulk

of

thischapter

has

beendevoted

to

explanations

and

comparisons

of

differentantennas

and

antenna-systeminstallation.

We've

providedinformation

to

help

you

make

a

decision

on

what

can

provide

the

bestsignalpossible

forthe

TX-11

b,

usingyour

own

antenna.

It's

pretty

obvious

thatmuch

time

and

attention

canbe

spent

in

pursuit

ofa

goodsignal

by

installing

a

goodantenna.Especially

if

you

live

far

awayfromradiostations,

orinan

areawithclassic

receptiontroubles.Beforethrowing

up

yourhands

and

despairing

the

thought

of

installing

a

morecomplexoutdoor

antenna,

wait

a

minute!We'dlike

to

remind

you

that

the

TX-11

bhas

uniquefeatures

and

performance,

making

the

choices

of

antennas,feedlines,

and

installationmethodslesscriticalthanwithvirtually

any

othertuner.

Still,

to

realize

the

maximumquality

of

performance

and

programming

excellence

offered

by

stereostations,you'llhave

to

pull

the

best

signalpossiblefrom

theairforthe

TX-11

b.For

thatreason,

youmay

want

to

select

oneofthe

betterantennaoptions.

If

it

comesdown

tothe

outdoorvariety,with

the

effort

and

cost

involved,

you

might

be

better

off

having

the

antennasysteminstalled

by

professionals.Thesefolks

know

alltheinsand

outs

of

qualitysignal

reception

for

yourspecificarea

and

circumstances.Plus,they

doall

the

climbingaround

onthe

roof.

A

companythatspecializes

in

this

type

of

work

can

give

youan

estimate

of

whatthey

feel

ajob

like

it

couldcost,allowing

for

somefurthercomparison

of

prices.

A

company

thatdoes

this

type

of

workoften

hasa

retailoutletthatstocksgood

antennas,materials,

andthe

hardwareyou'llneed

(ifyou

decided

to

do-it-yourself).

Taketime

to

checktheseservices

out

beforegiving

in

or

giving

up.

dipole

ribbonantenna

OO

17

r

Appendix

SECTION

1

FM

StereoSignals

andthe

Asymmetrical

ChargeCoupled

FM

Detector™*

FM

radiostationsstarted

life

broadcasting

a

carrierfrequency

modulated

by

music.When

you

listen

to"FM

108",

whatyourtuner

is

receiving

is

thatfrequency

—108

MHz

(megahertz,

or

millions

of

cycles

per

second)

—

modulated

bya

musicspectrumfrom

30Hzto

15

kHz

(KiloHertz,

or

thousands

of

cycles

per

second).

The

Federal

Communication

Commissionensures

(bylawand

threat

of

fine)

that

the

rock

music

onone

station

won't

interferewithclassics

onthe

next.

When

radiostationscameunderpressure

to

deliverstereosound,

somesystem

of

broadcasting

two

signals,

short

of

setting

up

another

station,became

necessary.

Earlyexperimentswereactually

tried

with

one

channel

onFM,the

other

onAM.

Needless

to

say,someother

solution

hadtobe

found.

One

constraint

ofthe

stereobroadcast

system

requiredthattableradios

geta

usablemonosignal

— not

just

the

left,

or

just

the

rightchannel.What

was

finallyadopted

and

approved

bytheFCCwasa

broadcastingsystemwhereboth

channels

(L+R)

wereavailable

as

usual.

To

supply

stereo,

a

differencesignal

(L-

R)was

developed

and

used

to

modulate

anothercarrier

at38

kHz.

Now

forthe

first

complication.

It

turns

out

thatbroadcastingthat

signal

in

stereorequired

too

muchfrequencydeviation(thedifference

between

the

necessarysignal

andthe

carrier),

sothe38kHzL-R

carrier

is

suppressed

anda

muchsmalleramplitude

19

kHz

pilot

is

added.

Mono

radios

use

only

the

firstblock

ofthe

signal.

The

SCA,

or

SubsidiaryCommunicationAuthority

signal,

is

oftenleased

to

companiesthat

specialize

in

commerical-free

backgroundmusic

for

stores,dentist'soffices,plusspecialprogramming

forthe

visually

impaired

—

evenforeignlanguagebroadcasts.

To

receive

anSCA

service,

a

specialtuner

is

needed.Thesesignalscan't

be

picked

up

ontheTX-11b.

The

components

ofthe

transmitted

FM

stereosignalthatconcerns

us

are

L+R

signals,

and

mostimportantly,

theL-R

signals.

The

graphic

representation

ofa

sample

FM

signal

shows

the

various

relationships

ofthe

different

signal

components

in

frequency

and

amplitude.

There

aretwo

morethings

you

shouldknow:

1)

actually,only

15%

of

the

L-R

signal

is

differentthan

the

L+R

signal;

2)theL-R

portion

of

the

transmittedsignal

is

veryprone

to

mishapsbetween

the

transmittingtower

and

your

TX-11

b.

It'sthissignalcomponentthat,

when

degraded,causesnoise

and

distortionproblems,usually

induced

by

multipath

reflections

off

hills,

buildings,

the

ground...

whatever.

The

AsymmetricalCharge-Coupled

FM

Detectoroperates

principally

on

theL- R

signalcomponents,improving

it

from

10

dBto23dB.

However,

itcan

onlyimprove

the

L+R

component

by1dB.Ifyou

kHz

15kHz

23kHz

19

kHz

(pilot)

FREQUENCY

«-

SCA

at

67kHz

receive

the

L+R

signalcomponentswell,

but

suffer

frompoor

L-R

reception,

the

AsymmetricalCharge-CoupledDetectorwill

drastically

improve

the

reception.

Ifthe

L+R

signal

is

poorlyreceived

as

well,

the

circuit

can

onlyhelp

a

little.

Degraded

L+R

reception

is

often

due

to

improper

or

inadequatesignal

strength.

Thiscouldindicate

a

distant

station,

orthe

need

ofa

betterantennasystem.

Almost

all

stereo

FM

receptionproblems

canbe

traced

to

poor

L-R

signals.

The

AsymmetricalCharge-Coupled

FM

Detector

is

extremely

effective

in

reducing

the

noise

and

distortionassociatedwiththistype

of

multipathinterference.

In

short,

itcan

providestereoreceptionthat

is

as

noise-free

asFM

broadcast

in

mono.Because

ofthe

nature

of

the

components

ofa

transmitted

FM

signal,

the

circuitcan't

significantlyimprove

a

poormonoprogram.

SECTION

2

AM

StereoSignals

andThe

UltraHigh

FidelityWideBand

AM

Stereo

Thistuner

is

absolutelyunique

in

that

its

basic

AM

performance

capability

is

essentiallyequal

to,andin

somecasessuperior

to,the

performancethat

FMcan

deliver.

AMis

inherentlyimmune

to

multipath

distortion,

the

primaryproblem

ofFM.

There

isno

fundamental

limitation

to

frequencyresponse,

distortion

or

noise

in

AM.

AM

systemshistoricallyhave

fallen

bythe

wayside

until

very

recently,

whenmanufacturershavetypicallyaddedthem

as

afterthoughts.

TheAM

systems

in

mostradiossoundterriblebecause

they

havebandwidththatextends

to2 or

3kHz;theyhavesignal

to

noise

ratios

inthe30sor

40s,instead

of

60s,70s,

or

80s;theyhave

distortionthat

is

usually3-8%

- not

high

fidelity

byany

means.

The

distortion

levels

in

this

machine

are

orders

of

magnitude

belowthat,

the

signal

to

noiseratio

isfar

superior,

andit

also

hasAM

stereo.

CQUAM™

AM

stereo

isa

brand

new

system

developed

by

Motorola.

The

wayit

worksbasically

is

that

a

signal

is

phasemodulated,

asub

carrier

is

phasemodulated

ontopofthe

regularcarrier,

anda

phase

detector

responsive

tothe

phasedeviation

of

thatcarrierseparates

out

the

left

andthe

rightchannelsignals.

Theway

it's

done

is;

the

L+R

part

ofthe

stereo

signal

is

broadcast

as

amplitude

modulated

AM,

theL-Ris

broadcast

on

thatsame

carrier

asa

phase

modulated

signal.

It's

actually

FM

because

whenever

you

have

a

phase

modulation

you

have

a

corresponding

FM

deviation

and

whenever

you

have

anFM

deviation,

you

have

a

correspondingphasemodulation.

Soby

modulating

the

phase

and

18

having

a

phasedetector,we'reable

to

detect

theL- R

part

ofthe

signal.

AnAM

detector

is

absolutely

insensitive

to

phasemodulation.

An

FM

detector,

when

properly

constructed,

is

insensitive

to

amplitude

modulation,

sothe

phasedetectorpicks

outtheL-R

becauseit'sphasemodulated

and

ignores

the

L+R

component.

The

output

of

eachdetectorthen

is

composed

ofan

L+R

signal

andan

L-R

signal.

Those

two

signals

are

combined

inan

appropriatematrix

to

produce

a

left

anda

rightoutput.

In

addition

to

thatthere

isa

pilottonethat

is

broadcast

at25Hzat

4%

modulation

to

turn

the

stereodecoder

onoroffand

light

upan

indicator

light

toletyou

knowthat

youare

listening

to

stereo.

The

featuresthatthistuner

hasof

receiving

AM

stereo

are

vast.

Our

circuitry,unique

toall

circuits,

hasa25Hz

pilotcancelling

circuit.

Most

AM

receivers,

to

eliminate

the

25Hzfromtheiroutput,willsimply

put

ina

bandstopfilter

and

nothingbelow

25Hz

getsthrough.

Our

system

is

flatdown

to

below

20Hzby

using

a25Hz

pilotcancellingsignal

so

the

pilot

will

be

cancelled

and

will

not

appear

atthe

output

asa

low

frequencyundesiredrumble.

Inthe

absence

ofa25Hz

pilottone,

the

stereodecoderwillswitchoff.This

is

desirablewhen

the

tuner

is

receiving

a

signal

in

mono,otherwise

it

would

be

somewhatnoisier.

The

difference

in

noise

is

theoreticallyabout3dB,

in

practice

we

find

it'sabout

14dB.

However,it's

14dB

noisier

whether

the

signal

is

strong

or

weak.

It

actuallyworks

out

betterthan

it

doeswith

FM.

Because

when

the

signal

islowinFM,youcango

fromstereo

to

mono

orgo

from

an

unlistenablecondition

in

stereo

toa

listenablecondition

in

mono.With

AM

thatdoesn'thappen.

InAM,the

signalwillremain

eminentlylistenable,evenwhenswitching

to

stereo

ona

weak

station.

This

isthe

only

AM

tunercapable

of

15

kHz

response

and

bandwidth.

The

typical

AM

bandwidth

is

approximately

3

kHz;goodenough

for

speech

andnot

reallygoodenough

for

highfidelitylistening.High

fidelityrequires

15

kHzor

more.Thisradio

hasa

unique

IF

system

(intermediatefrequency).

Ithas

beencarefullydesigned

tobe

perfectly

flat

15

kHzon

eitherside

oftheIF

carrier.Mostotherradios

have

a

responsethat

is

flatmaybe

to2 kHzand

several

dB

down

at

3

kHz;

the

best

of

them

are

usually

10dB

down

at6

kHz.

The

TX-11

b

system

is

perfectly

flat

andyou

willimmediatelyhear

the

difference.

When

you

listen

toanAM

radio,

you

willhearsparkle,life-liketimbres

just

thewayyou

hearthose

sparkly,

life-like

high

frequencytones

when

you

listen

toFM.

Why

areall

othertuners

are

only

3 kH

wide?

The

mainreason

is

that

itis

very

difficult

to

design

a

wideband

AM

radio.

It

requiresheroic

efforts.

It

requiresthat

theAM

antenna

be

widebandwithhigh

selectivity;

it

requires

a

greatmany

IF

stages.

It

requires

anIF

tuning

mechanismthattunes

simultaneously:

the

oscillator,

the

antenna,

and

theIF

must

track;

almost

impossible

todo

with

modern

electronic

varactictunedsystems.

Intheold

days,

the

tracking

wasa

matter

of

capacitorgeometry(some

ofyou

mightremembertuningcapacitors

that

had

serratedmetalinterleavedfinger).

Itwas

relativelyeasy

to

make

those

track

well

upand

down

the

band

simple

because

itwasa

matter

of

doing

the

geometryright.They

hadan

interestingquasi-

eliptical

shape

to

them

as

theyrotated

inandoutof

mesh.Modern

varactictunedsystems

are

verydifficult

to

maketrackproperly,

so

difficult

in

fact

that

most

AM

radio

manufacturers

gave

upand

made

the

bandwidthvery,verynarrow.

By

doing

so,

front

end

varacticmistracking

was

masked

bythe

narrow

bandwidth.Evenoscillatormistracking,oscillator,

IFandRF

mistracking

was

almosttotallymasked.Eventodaywithmostradios

you

willfinddifferentfrequencyresponses

on

differentsegments

of

the

dial.

Thelowendofthe

dial

may

have

a

higheraudiofrequency

responsewhenmeasuredthan

the

high

endofthe

dial

that

isdueto

mistracking.What

wehadtodowasto

develop

a

veryaccurate

trackingsystem

forour

varacters,

and

thisincludedenclosingthem

in

a

verypowerfulfeedbackloop

to

makesurethattheytrack

and

were

in

fact,alsowideband.

The

goal

wasto

make

the

bandwidth

15

kHz:

same

asFM.

Now

an

immediatequestioncomes

up;ifthe

tuner

is

capable

of

such

fine

performance,whatabout

the

broadcasttransmitters?

A

survey

in

the

Seattleareaimmediatelydemonstratedthat

the

majority

oftheAM

transmitters

are

broadcastingsignals

outto

15

kHz.Almost

allof

them

have

signalsthat

goouttoat

least

12

kHz,many

to

beyond

15

kHz.

You

willnotice

it

immediately.

15

kHzisan

acceptedminimum

for

highfidelity,

andtheFM

system

that

weuseis

limted

to

15

kHzandit

stopsinstantly

ata

brickwall

at

15

kHz.

TheAM

system

isnot

quitethatmuch

ofa

brickwall

andthe

responseactuallycontinues

a

little

bit

beyond

15

kHz.

We

can'tmake

it

20kHz

becusethatwould

putthe

modulatedcarriersquarely

ontop

of

an

adjacentchannel.Channels

in

thiscountry

are

spaced

20kHz

apart.

Thistuner

has

incrediblespecifications.

IthasanAGC

rangethat

is

approximately

10

timesgreaterthan

a

standardradio.Thatmeans

that

ona

strongstation,

the

outputlevelfrom

a

strong

to

weakstation

will

remainessentiallyconstant;

it'll

behave

in

thatregardlike

anFM

system;

a

weakstationwon'tdrop

in

volume

andit

won't

be

susceptible

to

airplaneflutter,won't

be

susceptible

to

fading

theway

a

regular

AM

radiowould

be.

That's

No.

1.

No.2of

course,

isthe

wide

bandwidthwhichresultssimply

in

high

fidelity

because

it

picks

upthe

highfrequencycomponents

ofthe

music.

19

SECTION

3

Specifications

FM

TUNINGRANGE:

87.5

MHz-108

MHz

ANTENNA

TERMINALS:

75H

coaxialinput

INTERMEDIATE

FREQUENCY:

10.7

MHz

FREQUENCY

RESPONSE:

20Hzto

15

kHz,

± 1

dB

SELECTIVITY

(At400

Hz):

90dB

(narrow);

35dB

(wide)

CAPTURE

RATIO:

1.0

dB

AM

SUPRESSION

RATIO:

IMAGERESPONSERATIO:

IF

RESPONSE

RATIO:

SPURIOUSRESPONSERATIO:

50dB;65dBwithCCD

110dB

100dB

OUTPUTLEVEL

(75Hz

deviation):

700mV,

600H

SYSTEM:

PPL

crystal-locked

digital

synthesizer

USABLE

SENSITIVITY

750:

50

dB

QUIETINGSENSITIVITY

75(1:

SIGNAL/NOISE

RATIO

75(1:

STEREOSEPARATION(wide):

MONO

16.1dBf/1.7>iV

82dB(a85dBf

STEREO

WITHOUTSTEREOWITH

CHARGE-COUPLEDDETECTOR

34dBf/14^,V

37dBf/19^V

74dB1(a85dBf

1kHz:

45

dB

100

Hz:

36

dB

10kHz:36dB

16.3dB/1.78^V

21

dB/3.1

(

85dB2(a85dBf

45dB(a-10dB

30dB(a-15dB

15dB@-23dB

AM

TUNINGRANGE:

SENSITIVITYTERMINAL:

RADIATED:

DISTORTION

(5mV/M)

SELECTIVITY:

IMAGE

REJECTION:

IF

REJECTION:

AGC

FIGURE

OF

MERIT:

AM

STEREOSEPARATION

(1

KHz):

FREQUENCYRESPONSE:

SIGNAL-TO-NOISERATIO:

POWER

REQUIREMENTS:

POWER

CONSUMPTION

DIMENSIONS

(w/h/d):

WEIGHT:

520

kHz-1710

kHz

20

nV

250^V/mfor20dBS/N

0.9%

42

dB

45

dB

34

dB

90

dB

40

dB

20Hz-15kHz,

±1.0dB

75

dB

120V,

60Hz;

240V,50Hz(optional)

15W

19V3.9V14"

11.9

Ibs.

1.

-

Includes

full

carrierjitter

of

testinstrumentation.

2.-

Withoutcarrierjitter.

Features

and

specifications

subject

to

change

without

nonce

20

Carver TX-11b User manual

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