B&K 1621 User manual

Instruction

Manual

Tunable Band Pass Filter Type

1621

TuMble B•mt

Pua

Fiher

T~

1821

Overload Power

033-0119

Filter

-20t

Hl

A small

light-weight

portable

filter

with

se-

lectable

bandwidths

of

3%

and

23%

(third

octave), covering

the

frequency range

0,2

Hz

to

20kHz

with

a

continuously

vari-

able

tuned

frequency. Powered

from

inter-

nal batteries

or

an external

DC

voltage.

Suited

for

use

with

B & K Sound Level

Me-

ters

Types

2203,

2209.

2210

and

2218.

B & K

Vibration

Meter

Type

2511.

and the

B & K

Wow

and

Flutter

Meter

Type

6203.

Can be

manually

tuned.

or

tuned

automati-

cally by,

and

synchronously

with,

the

B & K

Portable Graphic Level Recorders Type

2306

and

2309

for

recording spectra from

one

of

the

above

instruments.

+ BrUel &Kjaer

TUNABLE

BAND

PASS

FILTER

TYPE

1621

Applicable

to

instruments

with

serial

numbers

from

6941

24

Revision

September

1981

CONTENTS

1.

INTRODUCTION

AND

SPECIFICATION

(PRODUCT

DATA)

..................................................

.

2.

CONTROLS

..... .....

..

.. .. .... .......... .. .... .......

.........

.. .. .. .... ..........

..

.. ..

.......... .... .. ..............

.. ..

........ 3

2.1 . FRONT PANEL ......

.. ..

.......

....

..

.

..

.....

..

.........

.. ..

.

..

...

..

....

..

...

..

.....

..

.

..

.

..

3

2.2

. REAR PANEL ............. .

..

...

.......

....

.....

............

.

........

.

......

... .......

...............

..

4

3.

OPERATION

..............................................

...................................................................

.......

. 7

3.1 .

MOUNTING

....

.. .. .. ..

...

..

.........

..

.. ..

..

.....

..

...

.. .. .. ..

..

...

..

.

.. ..

..

.. .. ..

....

..

....

..

.. 7

3.2

. POWER SUPPLIES

AND

THEIR USE

.......

......

.......

.. ..

.....

..........

..

..............

..

.. 7

Internal

battery

supply

..

........................................................................... 7

Mains

battery

charger

....................................

..

........................................ 8

Mains

power

supply and

battery

charger Type

ZG

0199

.......................

..

.... 9

Mains

power

supply

Type

2805

................................................................ 9

External

DC

supply

...........................................................................

..

.....

10

3.3.

MANUAL

OPERATION WITH

SOUND

LEVEL

AND

VIBRATION METER

ETC

.....

11

3.

4.

AUTOMATIC

OPERATION WITH LEVEL RECORDERS

TYPES

2306

AND

2309

.

...................................

..

........

.......

..

......

........

..

.

12

4.

MEASUREMENT

CONSIDERATION

....................................................................................

.

15

4.1 . FREQUENCY CHARACTERISTICS

.........

.

.....

.

.......

.

.......

......

.. ..

.......

..

......

.......

15

4.2

. PHASE CHARACTERISTICS

......

.

.........

.

..

...

..

......

..................

....................

16

4.3.

FILTER SWEEP RATE CONSIDERATIONS

......

..............

......

.

........

..

..............

16

Selection

of

DC

or

AC recording

.................................................................

16

Choosing

the

meter

and recorder settings

....................................................

17

5.

SERVICE

AND

REPAIR

.

.......................................................................................................

20

FEATURES:

•

Tunable

band

pass

frequency

•

Frequency

range

0,2

Hz

to

20kHz

in

5

sub-ranges

•

Selectable

bandwidths

3%

or

23%

(

1/3

Oct.)

•

Two

alternative

input

voltage

ranges

•

Manual

tuning

or

tuned

automatically

from

Level

Recorders

2306

and

2309

•

Internal

battery

or

external

DC

power

supply

•

Small

size and

light

weight

for

ready

portability

USES:

• In

portable

systems

for

narrow

band

frequency

analysis

of

vibration

with

the

General

Purpose

Vibration

Meter

2511

• In

portable

systems

for

narrow

band

frequency

analysis

of

sound

and

vibration

with

the

Sound

Level

Meters

2203, 2209,

2210and

2218

• Recording

frequency

spectrograms

with

one

of

the

above

instruments

plus

the

Portable

Level

Recorders

2306

or

2309

The

Tunable

Band

Pass

Filter

Type 1

621

is

a

variable

frequency

band

pass

filter

intended

for

use as

an

external

filter

with

Bruel

and

Kjrer

measuring

instruments,

to

which

it

gives

the

ability

to

perform

narrow

band

frequency

analysis.

It

is

particularly

suited

for

use

with

the

General

Purpose

Vibration

Me-

ter

2511

for

narrow

band

fre-

quency

analysis

of

vibration,

and

with

the

Sound

Level

Meters

2203

2209,

221

0

and

2218

for

narrow

138-81

type

1

621

Tunable

Band Pass

Filter

Tunable Band Pass

Filter

Type

1621

Overload Power Filter

, Frequency Tuning •

On

12

Frequency Range

20-200

14

2 -

2~

•

0,2 - 2

• -

2k

-2

0k

Hz

Manual

Auto e

Start •• Briiei&Kjaar

band

frequency

analysis

of

sound

and

vibration.

Its

light

weight

and

battery

power

supply

make

the

1

621

the

ideal

portable

instrument

for

applications

away

from

fixed

power

sources.

Description

The

1

621

consists

of

a

tunable

single

pole

butterworth

filter

with

switchable

bandwidths,

its

own

power

supply,

and

the

necessary

control

circuits.

The

FILTER

selector

allows

the

fil-

ter

bandwidth

to

be

switched

to

"3%"

or

to

"23%",

which

are

the

bandwidths

·

between

the

half

power

points,

i.e. 3 dB

down

from

the

peak.

The

selector

also

has a

"Linear"

position,

that

by-passes

the

filter

.

Five

contiguous

frequency

sub-

ranges

can be

selected

from

the

in-

strument's

overall

frequency

range

between

0,2

Hz

and

20kHz,

each

sub-range

covering

one

order

of

magnitude.

The

frequency

may

be

swept

manually

through

the

sub-

range

by

a

large

control

knob

hav-

ing an

attached

pointer

that

sweeps

a scale

showing

the

filter

centre

fre-

quency,

and

the

preferred

centre

fre-

quencies

of

1/ 3 octaves

according

to

ISO R

266

.

Alternatively,

the

Filter 1

621

may

be

tuned

automatically

from

the

Por-

table

Level Recorders

2306

or

2309

when

they

are

interconnected

by a

suitable

cable

(see

specifica-

tions).

The

required

paper speed,

which

controls

the

sweep

rate,

is

F

i

htr!~UI

Medel

In

Oenmartc:

-

Fig

.1.

Rear

view

of

the

Type

1621

set

on

the

level

recorder,

and

the

sweep

is

initiated

from

the

1

621

.

The

filter

is

then

advanced

one

com-

plete decade

synchronously

with

the

recording

paper (QP 01

20,

OP

0124,

QP

0143,

QP

0224,

QP

21

00

and

QP

21

20).

During

this

process,

the

1

621

tuning

knob

does

not

move,

its

position

being

ir-

relevant.

After

one

decade,

the

1

621

frequency

range

is

changed

manually,

and

another

decade is

swept

.

Alternative

input

voltage

ranges

can be

chosen

by a

rear

panel

switch

.

"1

V RM

S"

matches

the

1 V

level

that

the

Vibration

Meter

2

51

1

delivers

to

external

filters

when

op-

erating

in

RMS

mode

.

"0,2

V

RMS"

should

be

selected

for

use

when

the

2

511

operates

in Peak

mode,

or

for

use

with

the

Sound

Level

Me-

ters.

An

"Overload"

lamp

lights

if

these

ranges

are exceeded.

The 1

621

is

powered

by

either

in-

ternal

batteries

or

by

al"l

external

DC

supply

.

The

alkaline

cells

sup-

plied

with

the

instrument

give

about

25

to

30

hours

continuous,

while

rechargeable

NiCd

cells

will

give

16

Frequency

Range:

0,2

Hz

to

20kHz

in 5

sub-ranges

Pass

bandwidth:

Switchable

3%

or

23%

(1/ 3

oct

.)

Attenuation

at

1/ 2

and

2

times

selected

frequency:

Switchable

34

dB

or

16 dB

Dynamic

Range

:

>

40

dB

RMS

with

3%

bandwidth

be-

tween

0,

2Hz

and

6kHz

>

35

dB

RMS

with

3%

bandwidth

be-

tween

6kHz

and

20kHz

>

40dB

RMS

with

23%

bandwidth

be-

tween

0,

2Hz

and

20kHz

Accuracy

of

indicated

frequency:

±

1,5%

at

25

°C,

with

additional

±0 ,

04

%

per

°C

Input:

BNC

socket

1 V

RMS

with

crest

factor

5

0,2

V

RMS

with

crest

factor

5

Input

impedance:

1 V

input:

approx. 1

MO

in

series

with

10pF

0,2

V

input:

approx.

200

kO in

series

with

1

OpF

Output:

BNC

socket

Impedance:

<

0,5

0 in

series

with

100pF

load

Impedance:

;;.

25

kO

to

20

hours

of

continuous

opera-

tion.

A

DC

voltage

can be applied

to

the

1621

to

recharge batteries,

and/

or

to

power

the

instrument.

External

sup-

plies can be

between

+4

and +

15

V,

or

alternatively ±

14

V DC,

which

can

be obtained

from

a

Battery

Charger

ZG

0133,

a

Power

Supply

ZG

0199

or

a car

battery.

When

the

ZG 0

113

or

ZG

0199

is used

the

instrument

can be operated and

the

batteries

re-

charged (at a reduced rate

with

ZG 0

113)

simultaneously.

Portable

Vibration

Analyzer

The

comp.Jetely

self-contained

Por-

table

Vibration

Analyzer

Type

351

3,

shown

in Fig.2,

consists

of

a

Vibra-

tion

Meter

2511A

and a

Filter

1621

installed

in a

rugged

hard-

foam

plastic

Carrying

Case

KA

2000

that

can

contain

1

2/1

2

of

a

19

inch

rack

module

.

Other

items

included

in

addition

to

the

standard

accessories

are

two

connection

cables

AO

0133,

six

rechargeable

NiCd

cells

QB

0008

and

a

Battery

Charger

ZG

011

3

for

the

1621

.

Fig.2

.

Portable

Vibration

Analyzer

Type

3513

Specifications

1

621

Gain

at

se

ected

frequency

:

0

dB±

1

,0

dB

Hum

and

noise:

Max.

Volt

-

age

0.2

Hz - 6 k

1 v

10mV

0.

2V

2mV

Distortion

:

< 1%

3%

Hz

6kHz

-

20kHz

18mV

3.

6mV

Environmental

conditions

:

23

%

0 .2 Hz -

20kHz

10mV

2

mV

The

instrument

performs

within

specifica-

tions

under

the

following

conditions

Operating

temperature:

- 1

0°

to

+

50°C

(

14°

to

122°F)

Humidity:

0

to

90%

relative

humidity

,

non

condensing

Electromagnetic:

Field

strengths

up to

100A

/ m

Power

Consumption:

Typically

200

mA

at

8 V

External

power

supply

:

+ 4 V to + 15 V,

or

± 14 V,

approx

. 2 W

Internal

power

supply:

6 x 1,5 V

cells

(IEC

TypeR

20)

Battery

life

:

25

to

30

hours

continuous

operation

with

alkaline

batteries

(supplied)

16 to

20

hours

continuous

operation

with

NiCd

cells

Charging

time

for

fully

discharged

batter

-

ies

approx

.

14

hours,

12

V

400

mA

Dimensions:

Height:

132,6

mm

(5,2

in)

Width:

139,5

mm

(5,5

in)

Depth:

200

mm

(7,9

in)

(B

& K

module

cabinet

KK

0024

, 4/

12

of

1

9"

rack

module)

Weight:

2,2

kg

(4

,91b)

with

batteries

Accessories

included

:

6

Batteries

QB

0004

7

-pin

DIN

plug

JP

0703

8-pin

DIN

plug

JP

0802

2 BNC

plugs

JP

0035

Accessories

Available

:

Synchronization

cable

for

2306

and

2309

:

AQ

0034

for

2306

from

serial

no

.

718058

and

for

2309

AQ

0182

for

2306

before

serial

no

.

718058

Rechargeable

NiCd

cells

QB

0008

Battery

Charger

ZG

011

3

Power

Supply

ZG

0199

2.1.

FRONT

PANEL

Overload

In

dicator

--:---JII.,

.

Frequency

Tuning

Knob

Sweep

Control

Sweep

Control

--~-

2.

CONTROLS

Tunable Band

Pass

Filter Type

1621

Frequency Tuning

Power

Filter Power On

·-----------:1---

Indicator

On

1----e

--

Filter

Selector

fJ811'""'cy Range

20-200

14

2-

2~

•

;oo

-2k

0

,2-2

•

Brilel &

K;.t

Frequency

,-----c---

Range Selector

Fig.2.1

.

Front

Panel

of

the

Tunable

Band

Pass

Filter

Type

1621

POWER ON INDICATOR:

This

lamp

lights

when

there

is a

sufficient

voltage

supply

to

the

instru-

ment,

from

internal

and

external

power

supplies.

FILTER SELECTOR:

Note:

It does

not

light

when

the

instrument

is

powered

from

a ±

14

V

DC

source

.

A

4-position

rotary

switch

for

switching

the

instrument

on

and

off,

and

for

selecting

the

required

filters.

"Linear",

"23%",

and

"3%"

are

avail-

able.

In

the

"Off"

pos1t1on,

the

power

is

off,

but

the

input

signal

is

directly

transmitted

to

the

FILTER OUTPUT socket.

In

the

"Linear"

position,

the

output

signal

is

unfiltered,

but

the

input

signal

is also

applied

to

the

23%

bandwidth

filter.

Thus,

when

the

23%

filter

bandwidth

is selected,

there

is

no

"settling

time"

for

the

fil-

ter;

the

filtered

signal

is

instantly

available.

3

FREQUENCY RANGE

SELECTOR:

FREQUENCY

TUNING

KNOB:

OVERLOAD INDICATOR:

SWEEP CONTROL:

SWEEP CONTROL INDICATOR:

THUMBWHEEL:

2.2.

REAR '

PANEL

FILTER

INPUT:

FILTER

OUTPUT:

4

A

5-position

rotary

switch

for

selecting

the

decade

required

for

analysis.

Two

scales

are

shown,

the

upper

scale

giving

the

decade

for

selection

and

the

lower

scale

giving

the

factor

by

which

the

scales

on

the

FREQUENCY

TUNING

KNOB

should

be

multiplied

to

give

the

actual

frequency

or

RPM

value.

A

continuously

variable

tuner

covering

a

range

of

one

decade

select-

ed

by

the

FREQUENCY RANGE SELECTOR.

The

outer

scale

shows

the

centre

frequency

of

the

band

being

swept

and

the

inner

scale

shows

the

RPM

value.

To

obtain

the

actual

frequency

or

RPM

value

the

scale

values

should

be

multiplied

by

the

factors

given

on

the

lower

scale

of

the

FREQUENCY RANGE SELECTOR.

The

small

black

circular

marks

in

between the

scales

indicate

the

prefered

centre

frequencies

of

the

1I 3

octave

bands

according

to

ISO

R

266.

The

FREQUENCY

TUNING

KNOB

has

no

effect

when

the

SWEEP

CONTROL

switch

is

set

to

Auto.

This

lamp

lights

whenever

too large a voltage is applied

to

the

FILTER

INPUT socket; depends on

the

setting

of

the

VOLTAGE RANGE SELEC-

TOR

on

the

rear panel.

A

3-position

paddle

switch

to

select

the

method

of

tuning

the

filter,

with

positions as

follows:

"Manual":

In

this

upper

position,

the

filter

is

tuned

manually

by

the

FREQUENCY TUNING KNOB.

"Auto":

In

this

central

position

the

filter

is

tuned

automatically

from

the

Portable Level Recorder· Type

2306

or

2309

when

a

suitable

cable connects

the

two

instruments.

The

sweep

will

always

start

at

0,2

Hz (or a decade

multiple

thereof)

and

will

sweep

one decade.

"Start":

When

the

switch

is depressed

to

this

spring-loaded

self

re-

turning

position and released (so

that

it

comes back

to

"Auto"),

the

Por-

table Level Recorder Type

2306

or

2309

will

start,

when

the

rele-

vant

cable connects

the

1

621

and

the

appropriate recorder and

will

sweep

the

filter

synchronously

with

the

recording paper over one

com-

plete decade (selected by

the

FREQUENCY RANGE SELECTOR) and

then

stop.

During

this

process,

the

position

of

the

FREQUENCY TUN-

ING KNOB is

irrelevant,

and

it

does

not

move.

This

lamp

lights

when

the

filter

is

actually

being

swept

synchronously

by

the

Portable Level Recorder Type

2306

or

2309.

At

the

end

of

de-

cade,

when

the

sweep

stops,

the

lamp goes

out.

The

knurled

knob at

the

bottom

centre

of

the

front

panel is

to

release

the

baseplate

to

enable

the

1

621

to

be

mounted

in

a rack or portable

carrying

case.

Turn

it

anticlockwise

to

release,

clockwise

to

tighten.

A BNC socket

for

feeding

the

signal

into

the

instrument.

A BNC socket

for

feeding

the

filtered

signal

out

of

the

instrument.

B&K 1621 User manual

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