Boonton Electronics 71A, 71AR - Page 19

Boonton Electronics 71A, 71AR

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(c)

Adjust

the

"CaMP

ADJ"

control

for

a

maximum

reading.

(Readjust

the

"e

ZERO"

control

to

keep

deflections

on

scale

if

required).

(d)

After

peaking~

zero

the

pointer

using

the

"c

ZERO"

control.

Once

adjusted~

the

"CaMP

ADJ"

control

need

not

be

re-

adjusted

for

some

time

(although

periodic

checking

during

extended

periods

of

operation

is

advisable)

unless

some

change

in

either

the

connection

system

or

the

nature

of

the

test

samples

substantially

effects

the

stray

capacitance

from

the

"HI"

post

to

ground.

In

such

cases~

readjustment

of

the

"CaMP ADJ"

control

is

required.

The

above

"CaMP

ADJ"

adjustment

procedure

will

suffice

for

the

majority

of

remote

measurements.

However,

to

obtain

the

greatest

possible

accuracy

when

using

the

l~

3~

10

or

30

pF

range,

and

when

the

specimen

has

sig-

nificant

capacitance

from

the

"HI"

post

to

ground,

the

following

procedure

should

be

followed:

(a)

Attach

the

coaxial

cables

and

test

fixture

(if

any)

which

are

to

be

used

in

subsequent

measure

ments

to

the

"

..

TEST"

posts

and

connect

a

specimen

typical

of

those

to

be

measured.

(b)

Set

the

"RANGE"

selector

to

the

lowest

range

on

which~

using

the

"C ZERO"

control~

a

reading

of

approximately

75%

of

full

scale

is

possible.

(c)

Adjust

the

"CaMP

ADJ"

for

peak

reading.

(Re-

adjust

the

"c

ZERO"

to

keep

deflections

on

scale

if

necessary.)

(d)

Disconnect

the

cable

at

the

low

post

and

zero

the

pointer

with

the

lie

ZERO"

control

(see

paragraph

3.4.2.3

below).

3.4.2.3

"C

ZERO"

Adjustment

The

front

panel

"e

ZERO"

adjustment

is

checked

by

switch-

ing

to

the

1

pF

range.

with

the

"CaMP 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

"e ZERO"

control.

(The

coaxial

cables

and

test

3-7

71A