Boonton Electronics 71A, 71AR - DC Output

Boonton Electronics 71A, 71AR

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3.14

DC

output

,

3.14.1

General

A

dc

analog

of

the

measured

capacitance

or

inductance

value

is

available

in

two

modes

(REC

and

DVM)

as

selected

by

con-

nections

at

the

rear

panel.

The

output

is

valuable

for

such

uses

as

application

to

a

recorder~

x-y

plotter~

digital

volt-

meter~

voltage

comparator~

etc.

Response

time

of

the

dc

output

is

less

than

10

milliseconds.

3.14.

2REC

Mode

By

connecting

to

the

"REC"

and

common

terminals,

the

output

for

all

ranges

varies

linearly

with

the

meter

reading

from

o

to

a

maximum

of

approximately

1.7

volts

(into

loads

of

10

megohms

or

greater).

3.14.3

DVM

Mode

Taking

the

output

from

the

"DVM"

and

common

terminals

pro-

vides

a

voltage

which

varies

from

0

to

100

millivolts

or

300

millivolts

for

full

scale

deflection~

depending

on

the

numerics

of

the

selected

range.

In

cases

where

the

output

is

used

with

a

digital

voltmeter

having

an

input

impedance

of

10

megohms

or

greater,

the

resistor

supplied

across

the

terminals

should

be

left

in

position.

For

digital

volt-

meters

having

an

input

impedance

of

1

megohm

this

resistor

should

be

removed.

If

the

input

resistance

of

the

DVM

is

less

than

1

megohm,

the

3:1

ratio

of

the

internal

attenuator

will

be

somewhat

in

error.

3.14.4

DVM

outEut

Adjustment

A

control

for

the

"DVM"

output

is

provided

on

the

rear

panel

to

permit

setting

a

digital

voltmeter

for

exact

agreement

with

a

standard

capacitor.

To

set

this

adjustment,

attach

a

standard

capacitor

that,will

produce

a

suitable

reading

(the

Model

7l-1A

Standard

Capacitor

is

convenient

for

this

purpose)

to

the

test

terminals

and

set

the

range

selector

to

the

appropriate

range.

(The

"CaMP

ADJ"

must

be

properly

adjusted

as

in

paragraph

3.10.2.)

with

the

digital

volt-

meter

properly

connected~

adjust

the

"DVM

ADJ"

control

so

that

the

digital

voltmeter

indicates

the

proper

value.

Once

adjusted

for

a

given

digital

voltmeter,

the

Model

71A

may

be

switched

from

range

to

range,

and

the

digital

volt-

meter

will

follow

correctly.

3-18

71A

d