Allied Radio Knight-Kit 83 Y 140 Manuel d'assemblage - Page 6

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With your KNIGHT

VOM you can perform a very

great variety of measurements.

The different measure-

ments are selected (a) by different panel jacks into

which the test leads are inserted and (b) by the posi-

tion of the Function Switch.

A number of scales on

the meter allow proper readings for any range of any

function provided.

The Function Switch has 18 posi-

tions and 2 decks.

This makes it possible to connect

the different components of the instrument so that d-c

and a-c voltages, direct and alternating currents, and

resistances can be measured.

The meter has a highly

sensitive 50-ua moving coil

permanent magnet move-

ment.

A calibrating resistor

(R3) assures the highest

degree of accuracy of the dial indications.

The meter

serves as the indicator for all measurements.

It has

separate scales for a-c voltage, d-c voltage, decibels,

xesistance and current.

Preliminary

Adjustments

Before

any measurements

are made,

be sure

the

instrument is placed squarely on a bench

where the

measurement is to be performed.

Always check that

the meter pointer is lined up with the zeros on the

left hand side.

If the pointer does not fall in line

with

these marks,

turn the bakelite

screw directly

above the word "'OFF"' either left or right until pointer

is positioned correctly.

Another reminder before using the meter for a par-

ticular type of measurement

is to make certain that

the operator understands fully how to handle this in-

strument,

as well as its capabilities.

With this in

mind, the following paragraphs are written, to give an

outline on how to use the KNIGHT VOM to your best

advantage.

How to Measure

D-C Voltoges

Coution:

Wherever possible, disconnect power

from

the equipment under test before connecting

the meter.

In cases where it is impossible to do

this, connect the leads separately and use only

one_hand at any one time.

Grasp the test prod

well back from the metal tip and make momentary

contact with the circuit under test by letting the

metal tip of the prod touch the point at which the

potential

exists.

Never

touch

any part of the

equipment under test with the other hand.

Plug the black test lead into the ""COM'' jack and

the red test lead into the ""V. ,

.A"' jack. First touch

the probe end of the black (negative) test lead to the

negative

side of the circuit to be checked.

Then,

leaving one hand free, touch the red (positive) test

probe

to the positive

terminal

of the circuit to be

tested.

It is a good practice

always

to start with the

highest

range

available,

a protection

for your

meter.

Then, after first indication, the switch should

be reset to the position in which more accurate read-

ings can be obtained.

If possible, make final readings

on a range on which the indication is in the right hand

half of the scale, because meter accuracy is based on

full scale value.

The

value of the measured

voltage can now be

read

from

the

appropriate

meter

scale,

taking into

account

the range

setting of the Function

Switch.

Read

tne meter

scale

whose

extreme

right-hand

marker is labeled with the full-scale value indicated

by the Function Switch or some multiple or submultiple

of it.

For d-c voltage readings, use only the black

scales marked "*DC''.

For the 0-2.5 v d-c range use the 250 v d-c scale.

Divide meter scale reading by 10.

Each minor scale

division equals 0.05 v d-c.

For the 0-10 v d-c range use the 10 v d-c scale.

Read scale directly. Each minor scale division equals

-2v d-c.

For the 0-50 v d-c range use the 50 v d-c scale.

Read scale directly. Each minor scale division equals

Iv de.

For the 0-250 v d-c range use the 250 v d-c scale.

Read scale directly.

Each minor division equals 5

v d-c.

For the 0-1000 v d-c range use

10 v d-c scale.

Multiply

scale reading by 100.

Each

minor scale

division equals 20 v d-c.

For the 0-5000 v d-c range use 50 v d-c scale.

Multiply reading by 100.

Each minor scale division

equals 100 v d-c.

If d-c voltages in excess of 1000 v but less than

5000 v are to be measured,

the red test lead has to

be plugged into the '5000 V DC' jack.

If working

with high potentials of this order, make doubly sure

that the Caution

paragraph at the beginning of this

section is strictly observed.

How to Measure A-C Voltages

NOTE:

same

precautions

as under

"Caution"?

in above

section

''How to Measure

D-C Voltages.

Plug the black test lead into the "'COM'' jack and

the red test lead into the "'V, .A''

jack.

Clip the

probe

of the black

test lead

to one

terminal

of the

potential to be measured and the probe end of the red

test lead should be touched

to the other terminal of

the potential.

Always

start

with

the highest

"'AC

V'' range

available, as a protection for your meter.

Then after

obtaining

the

first

indication,

reset

the

Function

Switch

to the position in which

a convenient meter

reading, preferably in the upper half of the scale, is

obtained.

Tum

the power on and observe the meter deflec-

tion.

The value of the measured voltage can now be

read

from

the

appropriate

meter

scale

taking into

account the range setting as indicated by the Function

Switch.

For the 0-2.5 v ac range use 2.5 v a-c scale.

Read scale directly.

Each minor scale division equals

0.05 v ac.

All other a-c voltage scales are chosen and read

in the same

way as the d-c scales discussed in the

section,

except that the red "'AC'' scales

are used.

If a-c voltages in excess of 1000 v, but not higher

than 5000 v a-c are to be measured,

the red test lead

has to be plugged into the '5000 V AC" jack.

working with high potentials of this order, be doubly

sure that the Caution at beginning of previous section

is strictly observed.