Heathkit IM-4100 - Page 47

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Gag

HEATHKIT?

Page

41

With

Instruments

NOTE:

In

the

following

steps,

keep

the

cabinet

shell

on

the

Counter.

(_

)

Turn

the

Counter

on

and

allow

it

to

warm

up

for

30

minutes.

This

is

MOST

IMPORTANT

for

an

accurate

calibration.

You

will

need

precision

equipment

to

calibrate

the

clock

and

the

input

sensitivity

of

your

Counter

in

the

following

steps.

This

calibration

can

be

performed

with

either

a

frequency

counter

and

a

signal

generator

(capable

of

a

1-30

MHz,

250

mV

output)

or

with

a

known,

stable,

laboratory

standard

frequency.

Determine

which

of

these

methods

you

will

use.

Then

complete

the

steps

under

the

appropriate

heading.

If

at

any

time

you

do

not

obtain

the

results

called

for

in

a

step,

refer

to

the

“In

Case

of

Difficulty”

section

on

Page

44

to

correct

the

problem.

CALIBRATION

WITH

A

FREQUENCY

COUNTER

AND

SIGNAL

GENERATOR

Refer

to

Figure

5

in

the

Illustration

Booklet

for

the

following

steps.

NOTE:

The

accuracy

of

your

Counter,

for

this

type

of

calibration,

depends

on

the

accuracy

of

the

test

frequency

counter.

(

)

Connect

the

test

leads

of

the

test

frequency

counter

to

the

output

terminals

of

the

signal

generator.

(

)

Also

connect

the

test

leads

of

your

Counter

to

the

output

terminals

of

the

signal

generator.

(

)

Press

the

POWER/TIME

BASE

switch

to

the

kHz

position

for

maximum

resolution.

(_

)

Set

the

signal.generator

to

any

convenient

frequency

between

1

MHz

and

30

MHz

at

250

mV

to

500

mV

output.

(_

)

Use

the

alignment

tool

and

adjust

the

OSC

ADJ

capacitor

(see

the

inset

drawing

on

Figure

5)

until

your

Counter

indicates

exactly

the

same

frequency

as

the

test

frequency

counter.

(

)

Disconnect

the

test

leads.

This

completes

the

calibration

of

your

Frequency

Counter.

Proceed

to

the

‘’Operation”

section.

CALIBRATION

WITH

A

KNOWN

LABORATORY

STANDARD

FREQUENCY

NOTE:

It

is

essential

that

the

known

frequency

source

(frequency

of

your

choice

between

1-30

MHz)

be

absolutely

stable.

The

accuracy

of

this

type

of

calibration

depends

entirely

on

the

accuracy

of

this

known

frequency.

(

)

Connect

the

known

frequency

to

the

test

cable

of

the

Counter.

(

)

Push

the

POWER/TIME

BASE

switch

to

the

kHz

position

for

maximum

resolution.

NOTE:

If

the

frequency

is

100

kHz

or

higher,

the

overrange

lamp

will

be

lighted.

( )

Use

the

alignment

tool

and

adjust

the

OSC

ADJ

capacitor

until

the

known

frequency

is

exactly

indicated

on

your

Counter.

This

completes

the

calibration

of

your

Frequency

Counter.

Proceed

to

the

‘‘Operation”’

section.