Metra Electronics DAT Combo Manual do Utilizador descarregar pdf (Página 66)

Although

it looks

like

any

other

microphone,

this

one doubles

as the

Safari Ill's

speaker.

Sound quality

is

quite good.

13.6

V (battery

supply)

was

4.6 watts

into

a 50-ohm

load.

Modulation,

under the

best

conditions,

peaked

at 80

%,

running

about

50%

on

an average

voice

level (if

there

is

such

a thing

as an

average voice

level).

Receiver

sensitivity

checked

out

at 1.8 uy

for

a 10 db

S -1-

N/N (signal

plus

noise

to

noise)

ratio. AGC

action,

that

is,

the vari-

ation in

audio

output

for

a 94

db variation

in RF input

signal,

was

23 db. Adjacent

channel rejection

was

slightly

better

than

35 db-not

super

-selective

by

any means

but

adequate

in

all but

the

most

heavily

con-

gested

CB areas

and

certainly

adequate

for

straight family

and

business

communications.

Talk And

Listen.

Because

of the

speaker

arrangement

we

could not

use the

standard

test for

audio power

output

as it

would

be

meaningless.

Subjectively,

the

signal repro-

duction

is quite

good if you

favor having

the

speaker

in

the microphone.

Unlike

very

early

CB transceivers

which

utilized

speaker

/mikes

and delivered

a muffled,

"hollow"

sound, the

Safari III

delivers

a notably

intelligible

sig-

nal from

the speaker

/mike.

To us,

response

appeared

devoid

of

all

highs and lows -it

was

all mid -range,

such

as you'd

expect

from

a

very

good

quality

intercom.

While

it was

a bit unusual

to

have

the sound coming

from

the

mike,

under high

ambient

noise levels

it proved

advantageous

to

be

able

to

direct

the

sound directly

into

the

ear.

But it

might prove

a

bit cumbersome

to utilize this

system

in

a quiet

office.

Many

options

are available

for the

Safari

[II.

You may purchase

individual

crystals

at

$2.50 each,

or

a full

set

at $69.95.

There

is

a portable battery

pack

that

accepts

D

cells

or

rechargeable

alkalines,

and

an

AC

power

pack that

also

doubles

as a battery

charger.

For

field use

there

is

a canvas

carrying

bag

and

a portable

antenna

specially

designed

to be

used

with

the

battery

pack.

For

additional

information

on

the

Safari

III, write

Dept.

20, Allied

Radio

Corp., 100

N.

Western

Ave..

Chicago,

III.

60680.

Shrunken

Antenna

for

Expanded

DX

Limited in

antenna space?

Here

is

a low -

cost

three

-band

system

that

will

fit

the aver-

age

backyard

and is

ideal

for

the

novice

amateur

operator

since

it's

designed

for

80,

40

and 15

meters.

The

system

is

constructed

with

300 -ohm

television

twin

lead

and consists

of

a

40-

and

80 -meter

dipole

with

the same

feed

line

at

the center.

The

entire system

is "shrunk"

to 100 ft.

by bending

the 80

-meter

section

back 12

ft.

at each

end. There is

no notice-

able sacrifice in

performance.

Construct

the antenna

to

the dimensions

in the diagram,

using

copper -clad

steel TV

twin lead.

Start by cutting

two

50 -ft. lengths

of twin lead

and attaching

an egg insulator

to

a

single insulator

to form

the

center feed

point.

From

each outer end, measure

back 12

ft.

toward the center,

then remove

a

5 -ft. sec-

tion

of

conductor from one

side of

the twin

lead.

Attach the feed

line and the

system is

ready to go

on

the air.

72

Either 72

-ohm

coax

or twin

lead

may

be

used

for

feeding

the

system.

A

72 -ohm

twin

lead reduces

the weight

which

the

antenna

must

support

and

keeps

the system

electri-

cally balanced.

You should

obtain

adequate

results

with

this

antenna system

of

80, 40,

and 15,

and

it will

also

work

fairly

well

on 20

and

10

meters.

But

for

the best

overall

perform-

ance. use

an antenna

tuner,

if

available.

300Á

TWMLEAD

EGO

INSULATOR

TO

SUPPORT

300n TWINLEAD

E40'

INSULATOR

TO SUPPORT

Cut

ANO

STRIP

EGG

out S' INSULATOR

SECTION NEAT

AO METERS

IOU'

IS"}--.--.4OANDISMrTEASae'

I

I-

72 n

TO

%MIR

RADIO

-TV EXPERIMENTER

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