Sharp R-309B Instruções de Operação descarregar pdf (Página 42)

5.4.4

20-dB

Eixcd-Attcnuntor

Loss

Check

Preliminary

Instructions:

a . A

20-dB

fixed

attenuator

is

supplied

with

the

CE-7

and

is

stored

inside

the

front

cover.

The

CE-7

attenuators

a r e

calibrated

in

terms

of

signal

volt-

age

at

the

output

of

the

20-dB

fixed

attenuator.

Refer

to

Table

5-5.

The

fi

xed

attenuator

must

therefore,

al -

way s be

used

if

the

output

levels

indicated

by

the

position

of

attenuat

or

knobs

ar

e to

mean

anything.

The

Table 5-5.

20-dB

Fixed-Attenuator

Loss Ch

eck

.......

~

f!!'

[e-

pur

pose

of

the

fixed

atte nuator

is

to

prote

ct

the

instrum

ent

wh

en

the

CE-7

is

dire

ctly

connect

ed

to a

tr

ansceiver

whi

ch

is

ac

cide n

ta

ll

y k

ey

ed to

trans-

mit.

Keying

a

tr

an

smitter

will

~

norm

ally

burn

out

th e

RF

fuse.

But

before

the

fuse

blow

s,

the

r e

sistors

in

the

fixed

a

tt

en

ua

tor m ay h

ave

been

[~

subjected

to a

transi

ent

ov

erl

oad

severe

enough

to d

am

age

them

and

ch

ange

their

v

alues.

Changed

ohmic

values

would

c

ause

cha nge d

attenu

ation

.

[

STEP

FUNCTION

TEST

POINT

OR

ADJUSTMENT

PERFOR

TvIANCE

STANDARD

lA

Feed

a

10-microvolt

signal

from

the

s ig nal

generator

into

the

r

ec

eive

r ,

lB

Note

the

receiver

meter

reading.

lC

Feed

a

100-microvolt

signal

through

the

attenuator

into

the

receiver.

lD

:'\ote

the

two

receiver

meter

readings.

NOTE

The

20-dB

fixed

attenuator

loss

may

be

checked

using

an

RF

Voltmeter

such

as

the

Boonton

9lD

in

place

of

the

receiver.

Perform

the

following

steps

as

required.

The

two

reading

s

should

be

within

0. 5 dB

of

on

e

another.

2A

Connect

the

output

of

the

signal

generator

into

the

RF

Voltmeter

through

a

50S?

termination

using

a

SO

S!

co

axi

al

cabl

e .

--

2B

Set

the

signal

generator

output

level

to

approximately

100

millivolts

and

not e

the

reading

on

the

voltmeter.

2C

In

sert

the

20- d B

fixed

attenuat

or

between

the

signal

generator

and

voltmeter,

and

note

the

diff

er

ence

in

reading

s .

20 dB

±O.5 dB

5-10

l

5601"0015"1

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 95 96

Comentários a estes Manuais

Sem comentários