Amber 5500 - Page 33

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Amber

model

5500

Owner’s

Manual

Version

07

2.4

SPECIAL

FUNCTIONS

There

are

several

lesser

used

parameters

that

'

can

be

set

using

SPECIAL

FUNCTIONS.

Ex-

amples

are

dBm

impedance

reference,

cer-

tain

GPIB

functions,

etc.

SPECIAL

FUNCTIONS

are

also

used

for

diagnostic

purposes,

special

programming,

to

override

auto-ranging

and

other

unusual

situations.

The

syntax

for

Special

Function

entry

is

the

special

code

followed

by

the

SPCL

key.

No

prefix

is

required.

Many

special

functions

have

a

two

part

code

separated

by

a

decimal

point.

The

first

part

of

the

code

specifies

the

function

while

the

second

part

of

the

code

the

sub-function,

value,

etc.

For

example,

the

dBm

impedance

can

be

set

using

Special

Function

26.

To

set

a

150

ohm

reference,

enter

26.150

SPCL.

The

following

are

some

of

the

more

commonly

used

special

functions.

2.4.1

WATTS

IMPEDANCE

REFERENCE

The

meter

can

express

the

input

signal

level

as

a

power

reading

by

calculating

a

Watts

value

using

the

measured

input

Voltage

and

a

stored

impedance

reference.

The

default

value

is

8

ohms

but

the

user

can

change

the

stored

reference

to

be

any

value

between

1

and

999

ohms

inclusive.

Use

Special

Func-

tion

25

followed

by

a

decimal

followed

by

the

desired

impedance

followed

by

the

SPCL

terminator

key.

For

example,

to

set

a

value

of

16

ohms

key'

in:

Programmable

Audio

Measurement

System

Section

2

fifififil-

The

currently

stored

impedance

reference

can

be

displayed

by

using

Special

Func-

tion

25.0.

2.4.2

dBm

IMPEDANCE

REFERENCE

dBm

is

in

fact

a

power

ratio

measurement

expressing

a

measured

signal

level

relative

to

a

power

of

1

mW.

The

5500,

like

most

dBm

meters,

measures

dBm

by

measuring

volts

and

calculating

the

power

presuming

a

refer-

ence

impedance.

The

default

impedance

is

600

ohms.

However,

the

user

can

change

the

reference

to

be

any

value

from

1

to

999

ohms

inclusive

using

Special

Function

26.

To

set

a

dBm

impedance

reference

of

150

ohms,

for

example,

key

in:

fill-m

To

display

the

currently

set

value

of

dBm

impedance

reference

use

Special

Func-

tion

26.0.

Remember

that

the

600

and

150

ohm

input

terminations

automatically

select

600

and

150

ohms

respectively

as

the

reference.

Also,

the

dBm

reference

described

here

is

for

LEVEL

measurements

only

and

does

not

affect

Generator

level

dBm

settings

which

have

their

own

independent

reference.

2-‘31'

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