Metra Electronics DAT Combo Instrukcja Użytkownika Pobierz pdf (Strona 58)

INSTANT

BFO

Using

The

BFO.

However,

in order

for

your

BFO

to

act successfully

as

a substitute

carrier

two

conditions

must be

met.

First,

it must

appear

in the

IF, frequency

-wise,

ex-

actly where

the

station's own

carrier,

if it

had

one, would

be.

Second,

strength

of mod-

ulation

and

artificial

carrier must

be the

same in

that IF stage.

Both problems

are

considerably

simplified

in this instance

be-

cause

the living

-room

type of

all -band

(SW)

receiver

you

are now

being

forced to

use

TO

LONGWAVE

RECEIVER

GIMMICK

OR

5 TO 10 MMF

CAPACITOR

INPUT

10

t/!;

LAST

IF STAGE

The

5-

to

1 0-mmf

capacitor reduces

detuning

of

IF

amplifier to

a minimum

but

after the

connection is

made last

stage should

be re-

peaked.

IF

signal goes

to

longwave

receiver

through

a short

length

of coaxial

lead.

AUDIO

OUTPUT

Doorbell

Silencer

Here's

a simple way

of

silencing that

door-

bell or

buzzer

so that

it

won't wake

Junior

taking his

afternoon

nap.

Pick

up a

small twist

switch with

threaded

shaft and

nut

for

panel

mounting

from your

hardware

store or "five-

and -dime."

Remove

the

cover or

housing

from your

doorbell

and

drill

a hole through

it large

enough to pass

the

threaded shaft

on

the switch.

Make

sure

the

switch body

inside

the

housing won't

in-

terfere

with

the bell

mechanism.

Remove

the

wire

coming

from

the

bell

transformer

from

its terminal

and connect

one of the

pigtail wires

on

the switch

to the

transformer terminal.

Then

connect the

transformer wire to

the other

pigtail wire

on

the

switch

by twisting

them

together and

taping.

You don't have

to turn

off the house

cur-

rent for this job -house

bell

circuits

carry

64

is

not very

selective,

which

means

a range

of

signals

at least

10 kHz wide

(5 kHz on

each

side of

the

tuned

frequency) will

be

passed

on

to the

LW

receiver

with

their

comparative

strengths

unaltered.

Then

be-

cause

just

about

all

superheterodyne

sets are

blessed

with

AVC (automatic

volume

con-

trol),

you

merely

have

to tune the

LW

re-

ceiver

up

and down

those IF

signals

until

the

desired

modulation

becomes

readable.

However,

because of

the military

rig's

own

high

degree

of

selectivity,

the

amateur

sta-

tion's

modulation

level will

probably

be

weaker

than normal.

To

compensate

for

this,

push

the

LW's

audio gain

(volume)

well

up.

How

Good?

Now before

anybody

gets

delusions

of

grandeur,

we'll

level

with

you.

This

system

will

not work

as well

as

a regu-

lar

Ham receiver.

It

is intended

strictly

for

those who

have

inherited

(gratis)

one

of

those

highly polished,

so-

called

hi

-fi

sets, or

even one

of

the many

transistorized

port-

ables whose

shortwave

band has

been

added

just "for

luck."

On the

other

hand, when

you consider

that

such rare

amateur loggings

as

FK8AB

New

Caledonia,

CR5SP Sao

Tome,

a number

of Antarctic

stations,

etc.

(who

use

almost

nothing

but single

side

-

band),

we

think

you'll

agree

that

the

effort

involved

in

using

this inexpensive

converter

combination

is

well

spent.

TRANSFORMER

POWER

WIRE

TWIST

WIRES

TOGETHER,

FOLD

AND

TAPE

DRILL HOLE

FOR SNITCH

DOOR

SELL

HOUSING

only

6

volts.

However,

it

is

wise

to do

so if

you

must stand

on

a chair or

stepladder.

Replace

bell

housing,

and

have someone

press

doorbell button

so you will

know

if the

switch

is

in the

"on" or

"off" position.

RADIO -TV

EXPERIMENTER

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