Boonton Electronics 71A, 71AR - Page 17

Boonton Electronics 71A, 71AR

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those

to

be

measured.

If

no

connectors

are

to

be

used,

insert

the

leads

of

the

specimen

in

the

center

conductors

of

the

"TEST"

posts.

(b)

Set

the

"RANGE"

selector

to

the

lowest

range

on

w.mch a

reading

of

approximately

75%

of

full

scale

is

possible.

(On

the

lower

ranges

the

"C ZERO"

control

may

be

of

help

in

obtaining

this

reading.)

(c)

Adjust

the

"COMP

ADJ"

for

peak

reading.

(Readjust

the

tIC

ZERO"

to

keep

deflections

on

scale

if

necessary.)

(d)

Disconnect

the

specimen

from

the

low

post,

leav-

ing

any

terminal

adapters

to

be

used

for

subse-

quent

tests

in

position;

zero

the

pointer

with

the

"c

ZERO"

control.

3.3.2.3

IIC ZERO"

Adjustment

The

front

panel

"c

ZERO"

adjustment

is

checked

by

switching

to

the

1

pF

range.

with

the

"COMP

ADJ"

control

properly

peaked

and

no

specimen

across

the

test

terminals,

observe

the

rest

position

of

the

pointer.

If

necessary,

the

pointer

should

be

brought

to

zero

using

the

front

panel

control.

Any

terminal

adapters

to

be

used

in

subsequent

measurements

should

be

left

installed

for

this

adjustment.

with

"100

pF

ZERO"

and

"c

ZERO"

controls

properly

set,

the

instrument

will

be

correctly

zeroed

for

all

ranges,

assuming

the

"COMP

ADJ"

control

is

properly

adjusted.

It

is

advisable

to

check

the

1

pF

zero

position

periodi-

cally

during

the

course

of

operation,

particularly

if

working

on

the

1

or

3

pF

ranges.

NOTE

The

front

panel

"c

ZERO"

control

is

a

dual

ratio

control

which

adjusts

a

variable

air

capacitor

having

a

full

360

0

of

rotation.

It

will

be

noted

that

the

"C

ZERO"

control

turns

very

easily

for

about

270

0

of

rotation.

At

this

point

the

torque

requirement

increases

abruptly,

indicating

a

shift

from

the

36:1

"fine"

adjustment

to

the

6:1

"coarse"

adjustment.

3-5

71A