BRUEL & KJAER 1623 User manual

Instruction Manual
Tracking Filter Type 1623
Filter Center Frequency
BrOel& Kjaer
Tracking
Filter
Type 1623
Tachometer
Input
r <;)
20mV - 1 20V
033-0280
Trigger level Battery ' Record er
Sync .
• • a • •
. .
.
On~
.
- 1V +IV
r- Manual Tuning /Preaet •--,
200Hz ·I 20kHz
2Hz
1
200Hz
,---- Tracking Mode -._,
Tachm . Filter Noise
In put Input Manual Fiher
-r-1-r---
-.ndwtdth
6% . 1 2% 23%
I
A small battery operated tracking filter
which can be synchronised with the funda-
mental frequency or any harmonic between
1 /99 and 99/1 of a periodic tuning signal.
Combined
with a vibration meter. sound le-
vel meter,
or measuring amplifier, the
1
623 allows signal analysis with respect to
a variable frequency reference signal, for ex-
ample vibration level as a function of shaft
speed. Frequency range covered is
2Hz to
20kHz with filter bandwidths of 6%, 12%.
and 23%. Tuned frequency synchronisation
signals provided for the Portable Level Re-
corder Type 2306 and for X-V recorders.
Manual tuning of the filter by means of a
front panel tuning knob coupled to a built-in
oscillator.
+ Bri.iel & Kjcer

TRACKING FILTER
TYPE 1623
Revision March 1 980

CONTENTS
1. INTRODUCTION AND SPECIFICATIONS (PRODUCT DATA) ................................................. 1
2.
CONTROLS .... ........ .. .. .... ........ ...... .. .. ...... . .. ..... .. .... ........ .. ........ .. .. .. .... .... .... .... ........ .. .. .. .. ........ 7
2.1. FRONT PANEL ....... ....... .. .. .. .... ........ .................................... ...... .............. 7
2.2 . REAR PANEL .. .............. .. .. ......... . .. .......... ........ ...... ............ .... .. ........ .. ...... 10
3. PRELIMINARY .................................................................................................................... ; 12
3.1. MOUNTING ...................... . ........ . ............................................................. 12
3.2 . POWER SUPPLY ...... .... ............................................................................ 13
Rechargeable Cells (8 & K no. QB 0008) .. . .. ........ .. ................ .. .. ...... .. .... .. . .. . 13
Dry Cells 1,5 V ....... . ...................................... ....... ...... .................. . .......... 14
External DC Supply 6 to 15 V ...... .. .... .. . .. . .. .. .. .... .. .. .. . .. .. .. .. ......... .. . .. ... .. ...... 14
Power Supply Type 2808 .................. .. ... .. . .. .. .. .. .. ..... .. ........... .. .... ............. 15
3.3. CHARGING THE INTERNAL BATIERY FROM THE AC MAINS ........................ 15
3.4. FUSE REPLACEMENT .............................................................................. 16
4. OPERATION .................................................................... . ................................................... 17
4.1. USING THE 1623 FILTER ............................................................... . ......... 17
4.2. SUITABLE TUNING SIGNALS .................................................................... 17
Photoelectric Probe MM 001-2 .............. .. .. ....... .. ... . .. . .. ....... .. . .. ..... ... .. .. .. .... 18
Magnetic Pickup MM 0002 .. .. ............... . .. .. .. .... .. ... ... .. ............. .. ............... 18
4.3. SETIING THE TRIGGER LEVEL ......... .. ............................................... . .. ..... 19
4.4. MANUALLY TUNING THE FILTER .... .. .. ....... .. .. .. .. .. ... .. ... .... .... ......... .. .. ..... .. . 19
4.5. SYNCHRONISATION WITH RECORDERS .................................................... 20
Synchronisation with the 'Portable Level Recorders Types 2306 and 2309 .... 20
Synchronisation with an X-Y Recorder ...... .. ................................ ..... .. ........ 22
4.6 . USING THE TRACKING FREQUENCY MULTIPLIER .................................... . .. 23
4.7. USING THE SPECIAL NOISE FILTER .... ...................................................... 23
4.8. FILTER SWEEP RATE LIMITATIONS ........................................................... 24
4.9 . TUNING FROM THE FILTERED OUTPUT SIGNAL ......................................... 25

FEATURES:
• Battery operated
• Frequency range 2 Hz to
20kHz
• Three selectable filter
bandwidths 6%, 12%,
23% (1 /3 Octave)
• Tunable from practically
any periodic signal
• Manual tuning facility
• Filter frequency/tuning
signal frequency ratio
adjustable between 99/1
and 1/99
• Synchronization signals for
level and X-Y recorders
• Wide dynamic range,
>60 dB, with crest factor
capability 4
• Large digital display of
filter centre frequency
• Low-pass noise filter for
tuning signal
USES:
•
Synchronous vibration
analysis of rotating
machinery
• Harmonic analysis of
vibration and
electroacoustic signals
• Filtering of response
signals in vibration testing
set-ups
• Harmonic distortion
measurements on
gramophone pick-ups
19-300
type 1 623
Tracking Filter
Filter Center Frequency Trigger
level Betterv
- - ~ -- ~------~ ------
Recorder
Sync.
~
11',:,// ~
L ___ - - ---------
On
Tracking
Filter
Type
1623
Introduction
The fully portable, battery oper-
ated, Tracking Filter Type 1
623 is a
narrow bandwidth filter whose cen-
tre frequency automatically locks
onto and follows the fundamental
frequency, or a harmonic, of a peri-
odic
tuning signal originating from,
for example, a tachometer or vibra-
tion transducer . Its small size and
built-in battery power supply make
it ideal
for field operation with the
general purpose Vibration Meter
Type 2511.
When combined with a sound lev-
el
meter, vibration meter, or mea-
suring amplifier, sound, vibration,
and other signals which can be con-
verted to electrical
waveforms, can
be analyzed
as a function of a vari-
able frequency reference signal. As
a typical example, can be quoted
the synchronous vibration analysis
of an engine being run up in speed;
the vibration level measured can be
plotted as a function of engine
speed, and
the development of re-
r Menual Tuning/Preaet '
e
2 00 Hz 20kH z
2H z 200H z
,---- Tracking Mode ~
Tachm. Filter Nol18
Input Input Manual Filter
sonances excited by the fundamen-
tal rotation frequency and its var-
ious
harmonics can then be stud-
ied.
Filters
Both the tuning signal frequency
and
the filter frequency ranges
cover
2Hz to 20kHz in one range
with automatic tuning. Three con-
stant percentage bandwidth filters
are provided with "white noise"
bandwidths of 6%, 12% and 23%
( 1/3 Octave) of the tuned fre-
quency.
Constant percentage band-
width filters give a constant resolu-
tion on a logarithmic frequency
scale and are therefore able to give
a
relatively quick analysis over a
wide frequency range.
The
filter, which has a dynamic
range
of about 70 dB, consists of a
digitally tuned pair of two-pole But-
terworth filters that give good selec-
tivity with an attenuation of
12
dB/octave. Characteristic curves
for the filters are shown in Fig .1.

Mea s uring Object : __ _
DDDDDD DO DDDO D O O OODOOOOOO
0 dB
Dat e:
10 dB
20 dB
30dB
40dB
50 dB
100 200
Lower Lim . Freq .:
Potentiomet er: Zero Lev
% Bandwidth =
12% Bandwidth =
3% Bandwidth =
500 1 000 2000
5000 10000
Hz Writ ing Sp eed:
mm l s 760855
Fig.1. Typical filter characteristics of Track -
ing Filter Type 1623
The large digital display on the
front panel, showing the frequency
to which the filter is tuned , is easily
readable in daylight conditions .
Filter Tuning
Practically any well defined peri-
odic signal with a level between
20 mV (noise free) and 1 20 V peak-
to-peak and a noise level less than
20 mV peak-to-peak, is suitable
for tuning the filter. The signal can,
for example, be obtained from a ta-
chometer, photo-electric transdu-
cer, eddy current probe, accelerome-
ter, microphone, force transducer,
magnetic transducer, capac1t1ve
transducer etc . (with suitable pream-
plifier where necessary) which will
give a signal in synchronization
with some periodic motion of the
measuring object.
A manually set trigger level en-
ables the periodicity of the tuning
signal to be detected in the most su-
itable portion of the waveform ; this
adjustment together with the hyster -
esis
effect exhibited by the trigger,
makes it possible for a reliable con-
trol pulse to be obtained from al-
most any periodic waveform .
In addition to the "tachometer" in-
put , two other possibilities exist for
automatically tuning the filter: (1)
Where the signal to be filtered has
a
well defined periodic content it-
self, this can also provide the tun -
ing
signal. (2) In cases where a peri-
odic
component of the signal to be
filtered is not clearly defined, the fil-
ter can be tuned through any single
decade using the filter 's own output
as a tuning source. In this case, the
tracking frequency multiplier facil-
ity, of course, cannot be used. One
2
would normally expect this closed
loop
control system to be unstable,
but with the un i que digitally tuned
filter used in the 1623, this is not
the case.
Note that for ordinary frequency
analysis work the 1 623 can be auto-
matically tuned by the Sweep Unit
Type 5555.
Photo-Electric Transducers
for "Tachometer Tracking"
For analyses on rotating machin -
ery, a reliable method of tuning the
filter is by means of a photoelectric
transducer which gives a well de-
fined pulse each time a photo-diode
or transistor is triggered by an inter-
rupted light source .
The B &K Photoelectric Tachome-
ter Probe MM 0012 is a combined
infra-red light source and pickup de-
vice built into a common housing ,
which is ideal for triggering the
1 623. It is positioned up to 15 mm
from a convenient rotating machine
part so that the light beam is ref-
lected back from a contrasting band
attached to the part . A white paper,
or aluminium foil strip glued onto a
black background is ideal. The de-
vice is fitted with a red filter to re-
duce interference from mains-oper-
ated lights. Power for the MM
001 2 is derived directly from an
extra shield in the tachometer input
socket (BNC) of the 1 623.
Fig.2. Photoelectric Tachometer Probe MM
0012, available as an accessory for
the Tracking Filter Type 1623
Manual Tuning
By means of a tuning knob on the
front panel, the 1 623 can be manu -
ally tuned and used as an ordinary
tunable bandpass filter for fre -
quency analysis work in the field .
The tunable range from 2Hz to
20kHz is covered in this mode in
two ranges (2Hz to 200Hz and
200Hz to 20kHz) . The frequency
tuning knob is also used to preset
the filter centre frequency to the ap-
proximate starting frequency of the
tuning signal. This significantly re-
duces the time taken for the filter to
automatically lock onto the tuning
signal , especially at lower frequen -
cies.
Auxiliary Sweep Unit An alterna-
tive to manual tuning of the 1 623
for ordinary frequency analysis
work is the Frequency Sweep Unit
Type 5555 available on special order
from the B & K Systems Engineer-
ing Group . The 5555 connects to
the tachometer input of the 1 623
and facilitates automatic frequency
sweep between two preset frequen-
cies selected on the front panel of
the 5555. Start frequencies of 2,
20, 200, and 2000Hz may be
chosen while the upper frequency
may be set to 20 , 200 , 2 K, and
10kHz . Coverage up to 20kHz is
possible by using the frequency mul-
tiplier facility in the 1 623 .
It may be seen from Fig.5 that for
a given filtered signal accuracy the
sweep speed is limited at high fre -
quencies by the writing speed of
the recorders, Types 2306 and
2309 . At low frequencies the limit -
ing factor is the 1 623 filter settling
time which in turn depends on the
filter bandwidth chosen . These val-
ues are set on the front panel of the
5555 so that changeover from one
limiting parameter to the other is au-
tomatic during sweep thus ensuring
the shortest possible analysis time .
The 5555 is equipped with a built-
in NiCd battery which may be re-
charged in-situ by battery charger
ZG 0113 which is supplied as an
accessory to the 1623 . Battery con-
dition is indicated on a meter .
Tracking Frequency Multiplier
This facility enables the filter to
be tuned to any ratio combination
between 1/ 99 and 99 / 1 times the
tuning signal frequency, thus allow-
ing any harmonic or sub- harmonic
(between these limits and within
the frequency limits of the instru-
ment) of the fundamental of the
measured signal to be examined .
This feature makes the vibration an-

Filter Bandwidth
6% 12%
23 %
(?(? (y
G
M
Filter Input
Amplitude
(oot~o!l'l
Overload !-
Detector
0 Manual
D
E
Manual
Tuning/
Auto -Cut-
r--- out
f > 200Hz
200Hz
~ LP Noise
Fi lter
6
{ Noise
4~ fFilter
Schmitt
Trigger
Preset/
Digitally Tuned
Analogue Filter
Filter Output J"\
~Frequency
~ (out of range)
Tuning
Range .__ _________ ~
Change Recorder
Logic
Control /
Range Changing -
r--------<--1 Synchron-
.-------+---i isation
-----o
Pulse a:
Log f
(for 2306)
and 2309
Memory
~-----iTFimej .,._ _____ ,Frequency
requency Display
Logic
~
Battery Charger
-
!---(included) 12 V,
-
400mA
Preset e---------1
~Preset
Power
Track
~Track
-Supply
0
1-- External Power Supply
Logic -
T
6Vto15VDC(4W)
J
I
t Denomina Numerator
tor
1 1 2 MHz
Tuning
Oscillator 1 1
-to-
Counter 1
to gg
Reference
1 99
Oscillator
Divider Divider
760851
Fig.3. Simplified block diagram of Tracking Filter Type 1623
alysis of machinery containing gear
wheels and shafts rotating at differ-
ent speeds a relatively simple mat-
ter. The multiplication ratio is se-
lected and clearly indicated by two
pairs of tens and units knobs on the
front panel.
Noise Filter
A special low-pass filter is built
into the tracking input circuitry in or-
der to attenuate high frequency rip-
ple which could cause false trigger-
ing at low frequencies . If the noise
filter is switched in, it automatically
becomes inoperative for tuning sig-
nal frequencies above 200Hz . This
filter is particularly applicable for fil-
tering out the 1 kHz synchronization
signal when the 1 623 is used in
conjunction with the Frequency Re-
sponse Test Unit Type 441 6 and
the Test Records OR 2009 and OR
2010 .
Principle of Operation
Reference is made to the simpli-
fied block diagram shown in Fig.3 .
The tuning signal is converted by
the Schmitt trigger . into a uniform
pulse form with a period time equal
to the period of the original input
waveform . This period time is mea-
sured by counting the number of pe-
riods of oscillation of a 2 MHz oscil-
lator between each trigger pulse,
and this number is then shifted into
the memory . The tracking frequency
multiplier function is achieved by di-
viding the pulse rate and/ or by di-
viding the oscillator rate (in effect
multiplying the pulse rate) by the fi-
gure selected on the denominator
and numerator knobs, respectively .
From the memory, logic circuits
digitally control the tuning of the
main filter according to the calcu-
lated period time . The filter range is
one decade of frequency, but range
changing is automatic until the fre-
quency limits are reached, after
which the out-of-range "frequency"
lamp lights. The filter is tuned over
each decade with a hyperbolic
sweep consisting of 175 discrete
steps . The step width varies be-
tween 0,8% and 2% of the tuned
frequency as shown in Fig.4. Due
to the stepwise method of tuning
the filter, the 1623 is not suitable
for use where phase accurate sig-
nals are required.
The memory also controls the fre-
quency display logic where the cal-
culated period time is converted to
frequency for the digital display . So
that the specified filter gain accu-
racy is
not significantly altered, it is
recommended that the frequency
tuning is not swept faster than indi-
cated in Fig.5. This chart is based
on the filter settling time . The exam-
ple shows a sweep from 10 Hz to
50 Hz with the 1 2% bandwidth fil-
ter which requires a minimum
sweep time of 5 s- 1 s = 4 s. With
a logarithmic sweep, the sweep
rate (determined by the lowest fre-
quency, 10Hz) will be 5 decades
per minute. The sweep rate could
be progressively increased with in-
creasing frequency to 25 decades-
/
min at 50 Hz .
Recorder Synchronization
Synchronization signals are pro-
vided
for controlling one of the axes
of a recorder in accordance with the
tuned frequency, so that vibration le-
vel
versus frequency or r. p.m . plots
can be made . Two forms of synchro-
nization signal are provided: A pulse
2,01,------ ------ -~
1, 6+------::..-------,..-- -- ----.,.,c...--1
'*- 0,8
c
0
:~
c
~
Cl
/
/
/
0,2.-""- ___ _...._ ___ _.__ ____ -::'
2 4 8 20
l------1 decade of frequency •I
760850
Fig.4. The filter is tuned through each de-
cade of frequency in steps. The step
width and therefore the filter defini-
tion varies between 0,8% and 2% of
the tuned frequency as shown . The
definition of the frequency display va-
ries
between 0,2% and 2%, as traced
by the broken line
3

output representing the tuned fre-
quency, on a logarithmic scale. This
is intended
for controlling the posi-
tion of the recording paper on the
portable Level Recorder Types 2306
and 2309. A switch on the rear
panel of the 1 623 selects either for-
wards and backwards paper move-
ment or forwards (increasing fre-
quency) paper movement only .
Unless
the Level Recorder Type
2306 is modified the recording
paper can
only be fed in the for -
ward direction . Where the tuned fre-
quency falls, for example due to a
reduction of
machine r.p. m., the
paper feed will stop. The paper feed
will commence only if that fre-
quency (or r.p.m.) is reached and ex-
ceeded again.
Modification Kits for the Level Re-
corder Type 2306 to enable it to
run both backwards and forwards
are: Kit No. WB 0250 for 2306's
with serial No . lower than 718
058. Kit No. WB 0329 for 2306's
with serial No. 718 058 and
higher.
Two-Channel Level Recorder Type
2309 may be run in both forward
and backward directions under con-
trol from
the 1 623.
The second form of synchroniza-
tion signal provided is a
DC ramp
voltage which is logarithmically pro-
portional to
the filter tuned fre-
quency. This operates in both direc-
tions and is intended for controlling
one of the axes of the X-Y Recorder
Type
2308 .
Power Supply
The internal power supply con-
sists of six, 4 Ampere - hour capacity
Nickel Cadmium rechargeable cells.
Their capacity is sufficient to cover
a
continuous operating time of 8
hours. The separate battery
charger, Type
ZG 0113, supplied
can recharge the cells from a com-
pletely discharged condition in
about
14 hours.
Alternatively, an external DC
power supply of + 6 V to + 15 V can
be used
to power the instrument.
The external power supply and bat-
tery charger are connected through
a socket on the rear panel of the
1623.
4
0,25
J. I I I
Note: Valid for denominator settings D<10
for D>10, multiply Time by -RJ
I I I
and multiply Sweep Rate by ~--1-----l
250
500
Frequency (Hz)
760863 / 1
Fig.5. Chart for determining the recommended maximum logarithmic frequency sweep rate
and
the recommended minimum frequency sweep time for filtered signal inaccuracy
<-1 dB (additional to specified filter gain accuracy)
:If CA.UttON
CH ll.ltGE VOLTAGE MOS T ONLY
IE APPUED WHEN USING
RECHAIIGEAB
LE BATTEIIIES
Fig.&. Rear panel view of Tracking Filter Type 1623
Photoelectric Tachometer
Probe MM 0012
Tracking Filter
Vibration Meter
Chart
Synchronisation
----l
I
I
L __
_,.•..:.'
,., .. ,.
.....
Level Recorder 2306 or 2309
or X-Y Recorder 2308
Filtered
Signal
Fig.7. Typical instrument set- up for synchronous vibration analysis
760852

Examples of Use
Vibration Analysis
The 1 623 is a valuable accessory
to the portable Vibration Meter Type
2511 . Fig.8 shows the two instru-
ments mounted in a sturdy carrying
case to make up a versatile vibra-
tion analysis system. With the two
instruments alone, manually-swept
frequency analyses can be per-
formed; the addition of a battery op-
erated,
portable Level Recorder
Type
2306 or 2309 will permit fre-
quency analyses to be recorded on
amplitude and frequency calibrated
paper. The addition of a tracking
pick-up will allow the vibration ana-
lysis of fundamental and harmonic
components, as a function of a ma-
chine 's running speed, to be per-
formed and recorded. These i nstru-
ments combinations are shown in
Fig.7 .
Fig.8 . The Portable Vibration Meter Type 2511 combined with the Tracking Tunable Filter Type
1623 mounted in a sturdy, hard-foam carrying case KA 2000
Monitoring/Measuring
~lerometer
Vibration Exciter
4801 + 4813
2626
Conditioning
Amplifiers
Measuring
Amplif i er 2610
Tracking Filter
1623
l ~ l: :c ~ : :l ~l
t® ;; : ~ : : ·. - · @ ;.; ....._ _____ .....
Power Amplifier
2707
~--~~--~~
Exciter Control
1047
Filter
Tuning
Si gnal
--,
I
I
I
I
Chart I
Synchronisation I
I
t
I
I
Constant Level Output I
-~ Adaptor ZM 0100 I
I I
L __ _________ _ _j
16 0989 /2
Fig.9 . Typical instrument set - up for vibration testing where a Tracking Filter Type 1623 is used for filtering the test object response signal
Vibration Testing
In swept frequency vibration test-
ing, a tracking filter is often used to
filter the test object response sig-
nal. A typical instrumentation set-
up
showing this application is
shown in Fig.9.
Used in the monitoring of vibra-
tion tests, the 1 623 will allow the
recording of both the fundamental
and the harmonic responses of test
objects.
Harmonic Distortion Measure-
ments on Audio Systems
Recording the various harmonic
components produced by audio rep-
roduction systems is straight-for-
ward when using the Tracking Filter
Type 1 623. The sweeping fre-
quency test signal from a sine gen-
Pickup under Test
erator or test recording is also used
to tune the tracking filter , and the
required harmonic is selected on
the 1623 multiplier-divider facility.
I I
t
Measuring Amplifier
2610
Chart Synchronisation 1
~-------....J
Level Recorder
2307 Filtered
nal
Tracking Filter
1623
760853 / 1
Fig.1 0. Instrument set - up for plotting harmonic distortion curves for gramophone pick - ups
5

A special filter ·is included in the
1 623 to attenuate the 1 kHz syn-
chronization signal which precedes
Filter Frequency Range:
2Hz to 20kHz continuously tunable from
tachometer input
Manual Tuning:
2Hz to 200Hz
200Hz
to 20kHz
Filter Bandwidth:
Switchable effective noise bandwidths of
6%, 12%, and 23% ( ~ 1/ 3 octave) con-
stant percentage bandwidth plus linear
position
(3 dB bandwidths of 5,4% , 10,8% and
21,7%)
Filter Type:
Two-pole Butterworth band-pass filter
Filter flank Slope: 12 dB/octave. (See
Fig .1.)
Octave selectivity (±1 dB):
6% B/ W 57,5 dB
12% B/ W 45,5 dB
23% B/ W 34 ,1 dB
Dynamic Range:
> 60 dB under 1 V RMS plus crest factor
4
Digital Display:
Gas display shows filter centre frequency
Overall accuracy: ± 1.5%
Filter Input:
BNC socket
Max. level: 4 V peak
Input impedance: 1 MO
Max. DC offset: 42 V DC
Filter Output:
BNC socket
Output impedance: < 1 0
Load impedance: ;;. 500 0
DC offset at output: < 2 mV
Filter Gain:
0 dB with following accuracy
Bandwidth 2 Hz to 2kHz 2kHz to 20kHz
6% ±1 dB ±
2dB
12%
± 0,5 dB ±1 dB
23%
± 0,25 dB ±0,5 dB
additionally + 0 dB -1 dB accuracy for fil-
ter sweep in accordance with Fig.5
each test band on the B & K Stereo
Test Records OR 2009 and OR
2010. An instrumentation set-up
Specifications 1 623
Noise:
< 1 mV RMS
Distortion:
< 0,1%
Tuning Signal ("Tachometer") Input:
BNC socket (with double shield)
20 mV to 1 20 V peak-to-peak
Max. Signal: including DC offset 42 V
RMS
Maximum noise: 20 mV peak-to-peak
Input impedance: 10 MO
Frequency range: 2 Hz to 20kHz
Power supply for pickup on inner shield
of socket + 7.5 V (direct internal connec-
tion to battery )
Trigger Level:
Adjustable + 1 V to -1 V
Hysteresis: 20 mV
Sweep Rate:
See Fig.5
Frequency Multiplier:
1/ 99 to 99 / 1 of tuning signal frequency
Output of Tuned Frequency for Recorder
Synchronisation:
Rear panel connection through 8-pin DIN
socket
1. Log f
----7 pulse for B & K Level Recor-
der Types 2306 and 2309
Max. sweep rate: 2 s/ decade
Frequency accuracy of pulse out-
put:± 2%
2. Log
f~DC for X-Y recorder e.g. Type
2308
Range 2Hz to 20kHz covers 0 to 7 V
Output impedance: 2,2 kO
Max. sweep rate: 2 s/ decade
Frequency accuracy of DC output:
±2%
for performing harmonic distortion
measurements on gramophone pick-
ups is shown in Fig.1 0.
Environmental Conditions:
The instrument performs within specifica-
tions under the following conditions :
Temperature: -1 0°C to + 50°C
Humidity: 0 to 95% relative humidity,
non condensing
Electromagnetic: Field strengths up to
100A / m
Internal Power Supply:
6 x NiCd rechargeable cells
Operating capacity: 8 hours continuous
External Power Supply:
Rear panel connection through 7-pin DIN
socket
Requires+ 6 V to+ 15 V, 3,5 W
Battery Charger:
B&KTypeZG0113
Input: 1 00 to 1 30 V AC or 200 to 240 V
AC
Output : 12 V 400 rnA. Short circuit pro-
tected
Time for complete recharge: approx. 14
hours
Dimensions: (excl. feed knobs etc.)
Height: 133 mm (5,2 in)
Width : 210 mm (8,3 in)
Depth: 200 mm (7,9 in)
(B & K module cabinet KK 0025 . 6/ 12
of 1 9" rack module)
Weight:
Including batteries, 3,2 kg (71b)
Accessories Included:
3 BNC plugs JP 0035
7-pin DIN plug JP 0703
8-pin DIN plug JP 0802
6 NiCd cells QB 0008
Battery charger ZG 011 3
Spare fuses VF 0032
Accessories Available:
Photoelectric Tachometer Probe MM
0012
Sweep Unit Type 5555

2.1. FRONT PANEL
Filter Center Frequency
Brtiel&KjSIII'
Tracking
Filter
Type 1623
Tachometer
Input
20mV - 120V
Max. 42V RMS
2. CONTROLS
Trigger Level Bettery
r- Manual Tuning/ Preset ~
.
200Hz
120kHz
2Hz 200Hz
•
Recorder
Sync .
~
r--- Tracking Mode ~
Tachm . Filter Noise
Input Input Ma nual Filter
r-- r-- r-- --
- . I
Bandwidth
6% 12% 23%
Lin .
I
Fig.2. 1. Front panel of the Tracking Filter Type 1623
FILTER CENTER FREQUENCY: A digital display of the centre frequency to which the filter is tuned;
with either Hz or kHz illuminated.
Frequency: When illuminated indicates that the signal from the tuning
source selected (possibly modified by the setting of the TRACKING FRE-
QUENCY MULTIPLIER knobs) is
outside the frequency range 2 Hz to
20kHz. Synchronisation signals to recorders are blocked when the Fre-
quency lamp lights but synchronisation is not lost.
Amplitude: When illuminated indicates that the filter input signal level
exceeds 4 V peak.
Preset: When illuminated indicates that the filter is not being tuned by
a
Tachometer Input signal or Filter Input signal and is therefore auto-
matically tuned to the frequency determined by the setting of the MAN-
UAL TUNING/PRESET knob multiplied by the N/ D ratio set on the
TRACKING FREQUENCY MULTIPLIER.
Track: When illuminated indicates that the filter is being tuned by the
tuning signal selected by depressing either the Tachometer Input or
Filter Input or Manual pushbuttons.
7

TACHOMETER INPUT:
TRIGGER LEVEL:
BATTERY:
TRACKING MODE:
BANDWIDTH:
MANUAL TUNING/PRESET:
TRACKING FREQUENCY
MULTIPLIER:
RECORDER SYNCHRONISATION:
8
A BNC socket accepting either single or double shielded BNC plugs for
a tuning signal input. The inner shield is connected through the
On/Off switch to the built-in battery supply (+ 7,5 V) and is intended
for powering a photoelectric pickup (e.g. B & K Type MM 0012). Signal
level 20 mV (noise free) to 1 20 V peak-to-peak. Maximum signal level
including DC offset 42 V RMS. Noise level less than 20 mV peak-to-
peak. Input impedan 'ce 10 MO.
For positioning a 20 mV wide amplitude window, through which the
tuning signal is viewed, within the range ± 1 V. Enables the periodicity
of the tuning signal to be detected in the most suitable portion of the
waveform.
Toggle switch which applies power to the instrument. The adjacent me-
ter indicates if the instrument is powered (by the internal or an exter-
nal supply) and if the supply voltage is sufficiently high (blue/green
area) or whether the supply voltage is too low or the battery should be
charged (red area < 6 V).
Three pushbuttons which select the source of tuning signal for the fil-
ter.
Tachm. Input: Selects a signal applied to the TACHOMETER INPUT
Socket.
Filter Input: Selects the signal applied to the FILTER INPUT socket
(rear panel).
Manual: Allows filter tuning by means of the MANUAL TUNING knob.
Noise Filter: Connects a special low-pass noise filter into the tuning
circuit to attenuate high frequency noise in the tuning signal. It be-
comes
automatically inoperative for tuning signals above 200Hz. See
section 4. 7.
Four pushbuttons to select effective filter bandwidths of 6%, 12%,
23% ("' 1 /3 Octave), or Linear.
In the linear position the filter input is connected directly to the output
socket.
With the TRACKING MODE - Manual pushbutton depressed the tun-
ing knob can manually tune the filter over the frequency range 2Hz to
20kHz in two ranges, 2Hz to 200Hz and 200Hz to 20kHz as se-
lected on the adjacent slide switch. Whenever the Preset window in
the display is illuminated the filter is tuned to the frequency deter-
mined by the position of the MANUAL TUNING/PRESET knob multi-
plied by the N/D ratio set on the TRACKING FREQUENCY MULTIPLIER.
Four ten-position switches which multiply the tuning signal fre-
quency by the ratio indicated by the upper (Numerator) knobs and
lower (Denominator) knobs. The centre frequency of the filter is there-
fore tuned to the tuning signal frequency x N/D. All ratios between
1/99 and 99/1 are selectable.
Three pushbuttons which direct the filter-to-recorder synchronisation
circuitry. These comments apply to operation with the Portable Level

Recorders Types 2306 and 2309. (Comments in parentheses apply to
operation with an X-Y recorder, eg. Type 2308) .
Reset Forward: When pressed, resets the pulse counter in the synchro-
nisation system to 0 position. Can take up to 10 s to achieve this condi-
tion. With an already synchronised level (X-Y) recorder, pressing the
Reset Forward button will move the paper (pen) forward to a "reset "
position on the next (same) chart about 4 mm before the 2Hz line
when paper QP 0120, QP 0143 or QP 0124 is fitted to the level recor-
der.
Reset Reverse: When pressed, resets the pulse counter in the synchro-
nisation system in the reverse direction to 0 position. With an already
synchronised level (X- Y) recorder, pressing the Reset Reverse button
will move the paper (pen) backwards to a position on the chart about
4 mm before the 2Hz line when paper QP 01 20, QP 0143 or QP
0124 is fitted to the level recorder. Applies only for Level Recorder
Type
2309 and when the Level Recorder Type 2306 is modified for
backwards movement and when the RECORDER SYNC. slide switch is
in the Fwd. & Rev. position.
Start: When pressed, indexes the pulse counter in the synchronisation
system forward to a condition in agreement with the frequency indi-
cated by the frequency display. With an already synchronised level (X-
Y) recorder, pressing the "Start" button will move the paper (pen) for-
ward to this frequency.
Holding the Start pushbutton in the depressed position locks all out-
puts from the RECORDER SYNC. socket. This prevents the recorder
paper (pen)
moving backwards and forwards while, for example, adjust-
ment are being made to the tuning of the filter. Synchronisation with
recorders is NOT lost, on release of the Start button the recorder
paper (pen)
will move directly to the tuned centre frequency.
9

2.2. REAR PANEL
· f'~ · Fwd.&
liF! ·I· Rev.
Fwd .
"Only
E. ><t . Power Supply Filter
Output
Made in Denmark
)f CAUTION
CHARGE VOLTAGE MUST ONLY
BE APPliED WHEN USING
RECHARGEABLE BATTERIES
Fig.2.2. Rear panel of the Tracking Filter Type 1623
RECORDER SYNC.: An 8 pin DIN socket giving access to the various synchronisation sig-
nals for X-Y and level recorders.
10
Pin 1 carries forward-reverse instruction for Level Recorder Type
2306 and 2309.
Pin 2 signal ground.
Pin 4 carries pen down instruction for Level Recorder Type 2309 and
for an X-Y recorder. When RECORDER SYNC. Reset Fwd. or
Reset Rev. are depressed pin 4, which is normally grounded, is
opened
to lift the pen until the reset condition is achieved.
Pin 7 carries a pulse output for automatic synchronisation of the re-
cording paper on the Portable Level Recorders Type 2306 and
2309.
Pin 8 carries a DC ramp voltage which is logarithmically proportional
to the filter tuned frequency (2Hz to 20kHz covers approx. 0 to
7 V). Intended for controlling one of the axes of an X-Y recorder.
DC ramp for X- Y recorder
0-7 V =2 Hz- 20kHz
Output impedance 2,2 k.Q
Ground
Paper synchronization for 2306 and 2309
Pen lift for 2309 and for X-Y recorder
(Pin 4 normally grounded, is opened
while 1623 is resetting)
110306 / 1
Fig.2.3 . Pin designations for RECORDER SYNC. socket viewed from
outside

EXTERNAL POWER SUPPLY:
The adjacent slide
switch is set to Fwd. & Rev. (forward & reverse)
when the 1623 is used with an X-Y recorder, a Level Recorder Type
2309 or a Level Recorder Type 2306 which has been modified (see
p.4 for Kit No.'s) to run in both directions. The Fwd. Only position is
selected when working with unmodified Type 2306 Level Recorders.
A 7 pin DIN socket
for connection of an external supply for powering
the instrument (+ 6 V to + 15 V DC) and a + 12 V charging voltage for
recharging the internal batteries. See section 3.2. Pin designations are
as
shown in Fig.2.4. Power consumption is approx. 3,5 W.
The adjacent slide switch selects either External Power supply or Inter-
nal Battery for powering the instrument.
+ 12 V charging --+---
---+----+ 6 V to +15 V
voltage
Power supply
ground
power supply
770305
Fig.2.4. Pin designations for EXT. POWER SUPPLY socket viewed
from outside
FILTEA INPUT: A BNC socket for applying the signal to be filtered. Nominal input level
1 V RMS. Crest factor capability 4. Input impedance 1 MO. Maximum
allowable DC offset 42 V DC.
FIL TEA OUTPUT: A BNC socket for feeding the filtered signal out of the instrument. Out-
put impedance < 1 0. Required load impedance ~ 500 0. DC offset at
output< 2 mV.
BATIERY COVER R_ELEASE Enables the side plate to be removed for access to the internal re-
SCREW: chargeable cells.
11

3.1. MOUNTING
12
3. PRELIMINARY
The 1623 cabinet is designed to fit the B & K modular cassette system. Its width is
6/ 12
of the width of the combining frame KK 0014 and the carrying case KA 2000 so
that it can be, for example, combined with the General Purpose Vibration Meter Type ''I
2511 (also 6/ 12 wide) to fill either of these.
To mount the 1 623 into the combining frame or the carrying case, first remove the base
panel of the 1 623 by loosening the base securing screw on the front panel, remove the
rubber feet and inclining leg, then remount the base panel into the base of the combin-
ing frame or carrying case. The 1 623 can then be slid into position and fastened with
the securing screw on the front panel.
Mounting Frame KK 0014
r (with 19" rock mo""'log brock•")
Fig. 3. 1. The cassette combining system
770318

Fig. 3.2. The Portable Vibration Meter Type 2511 combined with
the Tracking Filter Type 1623 mounted in a sturdy, hard-
foam carrying case KA 2000
3.2. POWER SUPPLY
There are several methods of supplying power to the 1 623, they are described in the fol-
lowing subsections . Whichever supply method is used, check that the battery condition
indicating meter deflects to the blue/green area, thus indicating sufficient supply vol-
tage .
3.2.1. Rechargeable Cells (B & K no. QB 0008)
Six rechargeable nickel-cadmium cells are supplied with the 1623. They are each rated
at 1 ,2 V with a capacity of 4 Ah and are specified to give at least 500 charge cycles be-
fore replacement i·s necessary. The need for replacement is indicated by the cells failing
to reach a fully charged condition after being left on charge for 14 hours or more (with
battery charger ZG 0113 supplied). A fully charged battery can be expected to give a con-
tinuous operating capacity of 8 hours. The cells are mounted in the 1 623 as follows:
1. Lay the instrument on its left side panel (viewed from the front) imd remove the
screw marked Battery on the rear panel. The side panel can now be slid out of the
instrument body.
2. Place the cells in the compartment with their polarities as indicated. (See Fig.3.3.)
WARNING: There is a possibility of explosion if recharging is attempted on cells
that have been fitted with their poles reversed.
3. Replace the side panel and stand the instrument on its feet, or use the stand to
raise the front panel as desired.
4. Slide the power supply switch on the rear panel to Internal Battery.
5. Set the BATIERY switch to On, and check that the battery condition indicating me-
ter registers in the blue/green area, indicating that the battery is in usable condi-
tion .
13

Fig. 3. 3. Location of the six cells in the battery compartment of the
Type 1623
6. Switch the instrument Off to conserve battery power if it is not to be used immedi-
ately.
Note that the Battery Charger Unit ZG 0113 has a current capability which is about
equal to the current consumption of the 1623 when operating, so that with well-
charged cells, the ZG 0113 will act as an AC Mains power adaptor. (The power supply
slide switch on the rear panel is set to Int. Battery.)
3.2.2. Dry Cells 1,5 V
Ordinary 1,5 V dry cells to IEC R 20 (33 mm x 60 mm high) can also be used. "Long
Life" alkaline cells will give an operating capacity of about 12 hours continuous opera-
tion while ordinary cells will give 0,5 to 2 hours.
Never attempt to recharge ordinary or alkaline cells - there is a danger of explosion.
3.2.3. External DC Supply 6 to 15 V
14
A car battery or other DC source of between 6 V and 15 V with a power capability of at
least 3,5 W can be used to power the 1623. The source is connected to the 1623 via
the rear panel socket marked EXT. POWER SUPPLY with the connections shown in
Fig.3.4.
+
6 V to 15 V
;;;. 3,5 w
7 Pin DIN
Plug JP 0703 '
+ 6 V to+ 15 V
~--------------------~ov
770303
Fig.3.4. Connections for external power supply. Soldering side of
plug shown