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bottom

uiew,

showing

typical

]|

]

]

]

]

x

'

Pr`

`71

Q L

O

22

SecaOna

.LUBRICAT10N

35.

Generol Lubricotion

lnstuuctions

a.

Several

factors

determine the

frequency

with

which

parts

in

the signal generator

need

to

be

lubricated.

These

factors

are-.

(1) After

a

certain length of

time,

most

lubri-

cants

become wax-like

and

cake up

in

spots

so

that

they

will not

give

the

proper

lubrication.

In these

c ses,

the

old

lubricant

should

be

cleaned off and

new.

lubricant

applied.

(2)

The signal

generator

may be operated

in

a

location

where

extreme

temperature

changes

occur;

the

lubricant

then

will

be

hard

because

of low

temperatures

when

the

signal

generator

is not

in

operation

and

extremely soft

or liquid

when

the

signal

generator

is

operating

and

the

temperature

risos.

\{here the

tempera-

32

ture

change

is great,

the

condition

of

the

lubricants

must

be

inspected

frequently.

In some

locations,

the

foreign

materials

present

in

the

air, such

as

dirt,

sand,

smoke,

metal

filings, or

g ses,

may

enter

the

signal generator

and

mi-x

with

the

lubricant

and

form

a

grit,

or

decompose

the

lubricant.

If

grit

is

formed,

it rvill

act

as

an

abrasive

and

cause

serious

wear.

The

old

lubricant

should

be

cleaned

away

thoroughiy

with

solvent

(SD)

and

fresh lubricant

applied

frequently.

Although

the

signal

generator

is

protected

against

humidity,

a

certain amount

of

moisture

may

enter

and injure

the

moving

parts.

tr4oisture

condensation

is

preva-

Ient

when

the temperature

drops

quickly

and the

relative

humidity

is

high.

If

(3)

(4)

@

Y

=]

O

a

=]

k

t

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of reacrtance

tube V5,

R49

is

the

fi'ont

panel

control

which

sets

the deviation

level of the r-f oscillator.

c.

Tube

V9,

a

6C4

triode,

is r.'onnected

as a

calho

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57.

l-F

Attenuotor

(fig.

z7)

tz. A

simpiifiecl

scirematic

ciiaglam

of

tire

i-f

attenuator

is shorrn

in

figure

27.

Any voltage

supplierl

b1-

the

i-f

output

stage

passes

through the

i-f

attenuator

before

reaching

the

i-f

oulput,

cable.

The

attenuator

is

made up

of

trro switches

and a

resistor

pacl

rr-hich

allows

20-db

(voltage

ratio

of

10

to 1) attenuaticn

steps

betrveen

the

contacts in

each

position

of

the

If'

\{ICROVOLTS

srvitch.

The

purpose

of

the

pad

and

srvitch

54

is

to

atten-

uate

the input signal

and

provide

a

constant

irlpeclance

to

the

output

cable.

The

pacl

consists

of

resislors

R76 through

R83.

Wren

the Itr'

\IICRC\-OLTS

sii,itch

is turned

to

the

1.0 YOLT

position,

srritch

S5,

rr,hich

is

operated

by

a

cam on

54. alloivs

the direct

output

of

1

volt from

the

i-f

amplifier

stage

to

be

supplied

to

the

i-f output

cable.

Resistors

R75 and

R103 are sq,itched

into

the attenuator

orrtput

circuit in

the 1.0

YOLT

position

to

maintain

thc

necessary

orrtput

im-

pedance.

CR2

1N21B

D.

The

output

from

the

attenuator

passs

thlough

a sholt

length of

coaxia,l

cable

to

jack

J6

oa

the

front panel,

and

then through

the

flont

panel

tlirough

a

cablc

r.hich

is

permanently

con-

nected.

The i-f

oulput

cable is

terminated

by

resistor

R84.

Looking

into

the

generator,

a

25-

ohm

output

impedance

is

seen.

Connection

is

nrade

from

this

cable

by

means

of

ailigat,or

clips.

58.

R-F

qnd

l-F

Output Metering

Circuits

tr'igure

28

shows,

in

a

simplified

form,

the

metering

circuit t hich

me sures

the

voltage

inputs

to the

r-f

and

i-f

output attenuators.

Depending

on

rhe position

of

OPERATION

su'itch

51,

either

the r-f or i-f voltage

is measulcd.

s,.

In

the IF

position

of 51,

a

portion

of

the

i-f

attenuator

inpub voltage

is

rectified

bv

crystal

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2o00r--Gu|{*--r-1?ooo

+,,*+

17

TM1257-54

3996340-56(Face p

Vi V2 V7 Ve v9

5CCI .9uu

E

1 500 0

P9T VVV T

]~u

~~~v

(equipments

after

seri,al No.

110).

TO LUG:

Si SECT:

P

\

VVV \

V 2

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