Boonton Electronics 71A, 71AR - Page 10

Boonton Electronics 71A, 71AR

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(c)

-Measuring

a

standard

capacitor.

(d)

Testing

a

specimen

having

markedly

different

"HI"-to-ground

capacitance

than

those

tested

previously

with

a

given

connection

system

(as

caused

by

considerable

differences

in

internal

construction,

encasing,

or

terminations).

~

CAPACITANCE

TEST:

BNC

connectors

for

the

test

specimen.

Measurements

may

be

made

either

locally

or

remotely

by

means

of

coaxial

cables.

CAPACITANCE

DIFF:

A

given

capacitance

connected

to

the

"TEST"

terminals

produces

an

accurately

calibrated

up-scale

reading.

Attaching

the

same

capacitance

to

the

"DIFF"

post

causes

a

comparable

down-scale

reading.

These

connections

are

useful

for

such

functions

as

making

differential

capaci-

tance

measurements,

extending

the

measuring

range

upwards,

or

extending

the

range

of

the

"c

ZERO"

control.

There

are

certain

limitations

on

the

use

of

the

"DIFF"

posts

which

are

detailed

in

paragraphs

3.5, 3.6,

and

3.7.

~

L/c:

This

switch

selects

a

condition

for

measurement

of

either

inductance

or

capacitance.

INDUCTANCE:

Test

terminals

for

inductance

measurements.

Measurements

should

be

made

directly

at

the

terminals.

Use

of

even

short

test

leads

should

be

avoided,

if

possible.

<:~

ON

(PUSH):

The

main

power

switch

(push

for

on,

pull

for

.

off)

i

the

translucent

red

button

serves

as

the

pilot

light.

This

assembly

also

contains

the

primary

power

fuse,

which

may

be

removed

by

rotating

the

black

ring

counterclockwise

and

withdrawing

the

fuse

holder.

~

MECHANICAL

ZERO:

This

adjusts

the

meter

pointer

to

a

mechanical

zero.

It

should

be

checked

with

the

instrument

switched

off.

I

I

@ OPERATE/CAL

l/CAL

2

(Model

7lAR

only):

For

measuring,

th~s

selector

is

left

in

the

lIOPERATElI

position.

Set

the

"CAL

1"

and

"CAL

2",

it

switches

in

the

internal

100

pF

standard

capacitor

for

high-Q

and

low-Q

calibration

checks,

respec~ively.

(See

paragraph

3.10.4.)

METER

ON/OFF

(Model

71AR

only):

There

is

no

interaction

between

the

indicating

meter

and

the

dc

output

except

for

a

small

counter-emf

from

the

moving

coil

of

the

meter

move-

2-5

7lA