Metra Electronics DAT Combo Manual de usuario descargar pdf (Pagina 54)

INPUT

MODE

SWITCH

OPERATE

SWITCH

hi-LO

DEVIATION

FREQUENCY

SWITCH

MODULATION

TEST

a

special

mark

at

the maximum

permitted

deviation of 1350 Hz.

The Acid Test. Is the C -12B

reliable? Is

it

really a

secondary

frequency standard

the

CBer and the

service shop can

depend

on?

To

find

out,

we

checked

the C -12B against

a Hewlett-

Packard

counter

with a

known

accuracy

of 1 Hz. The results are

shown in

the table.

Column 1 shows

the channel, col-

Channel

Frequency

in Hz

C-128

Output

Error

in Hz

1

26965000

26964971 29

2

26975000

26974990

10

3

26985000

26985002 2

4

27005000

27004992 8

5 27015000

27014992

8

6 27025000

27024995 5

7 27035000

27035002 2

8 27055000

27054986

14

9

27(65000

27065014 14

10

27075000

27075004 4

11 27085000

27085018 18

12 27105000

27104979 21

13

27115000

27114984 16

14 27125000

27125000

1

15 27135000

27134951

49

16 27155000

27155002

2

17 27165000

27165009

9

18

27175000

27175002

2

19 27185000

27185004

4

20

27205000

27205016

16

21

27215000

27215003

3

22 27225000

27225019

19

23

27255000

27255037

37

24

No crystal

provided

(spare)

58

OSCILLATOR

TUBE

A.F.

AMP

a -ll

COUNTER

BATTERY

COMPARTMENT

CRYSTAL

BANK a

INDIVIDUAL

FREQUENCY

CALIBRATING

TRIMMERS

Operating

panel of

the International

Crys-

tal C -12B (left)

and

internal layout (above)

shows

th^

major portions of

this ac-

curate

( 100 Hz) frequency

meter for CB.

umn 2 the assigned

frequency, column

3 the

actual

reference frequency

of the C -12B, and

column 4

the

C -12B's

error

in Hz. Note

that the error

is

less than

the specified

100

Hz and

in many instances

less than 10

Hz.

Allowing for

interpolation

of

the

meter

scale

(which is calibrated

in units of

60 Hz),

the

maximum error

of

the model

we

obtained

would be

considerably

less

than

100 Hz. Fre-

quency drift

from the moment of throwing

the power

switch

to

the moment

of measure-

ment (a

few

seconds)

was less

than

10 Hz,

again

keeping total

error

well

within

the

claimed 100 Hz.

As far as

the

mechanical operation is con-

cerned, things couldn't

be easier.

You feed

in the transmitter's

signal, set

the mode

switch to

RF,

adjust

the level control

until

the

meter

pointer

lines up

with

a

scale mark,

then switch to

deviation. The

meter then in-

dicates frequency deviation

instantly;

total

measurement

time is less

than 10 seconds.

Other

Functions. To use the C -12B as

a

power meter, you simply

set the mode switch

to

RF

and

turn the

level

control

full clock-

wise. The

C -12B

then indicates the transmit-

ter's output power, and

in the

unit

we

tested

it does

so

with

an accuracy

better than the

claimed

Vs

watt.

For example,

when

the

actual power

fed into the unit

was

3.0

watts,

the C -12B

indicated an input

of

3.2

watts.

Since

the C -12B's

meter

is

damped, a sus-

tained

word rather than a string

of words

must

be used

for

modulation

tests in

order

to

permit the

meter

to

rise to

peak value. For

example,

when the speech

input was a long

(Continued on

page 118)

Rnaro-TV

EXPERIMENTER

1 2 ... 49 50 51 52 53 54 55 56 57 58 59 ... 113 114

Comentarios a estos manuales

Sin comentarios