Kenwood VT-172 User manual

©PRINTEDIN JAPAN
NOISE METER
VT-172
INSTRUCTION MANUAL
KENWOOD CORPORATION
KENWOOD

CONTENTS
1. GENERAL3
2. FEATURES 3
3.SPECIFICATIONS4
4.CONTROLSANDINDICATORS7
5.OPERATION10
6.PRECAUTION11
7.MAINTENANCE12
8.ADJUSTMENT. 13
9.APPENDIX16
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1. GENERAL
The Noisemeterisanhigh-sensitiveelectronicvoltmeter
havinga maximumsensitivityof10M/fullscale.Its
widefrequencyrangecovers from 10Hzto500kHz(1mV
~300V) andthefivetypesofweightingareselectable.
Inaddition,DINor CCIR quasi-peakoraverage
detection with RMSdisplayisselectable,making
possibleS/Nandnoisemeasurementsinaccordance
with J IS-A, DIN NOISE, DINAUDIO, CCIR and CCIR/
ARM standards.
The unitsarealsoprovided with anoverloadindicator,
a 10dBrangerelativereferenceadjustmentandACand
DC outputs.
a. 10#Vfullscalemaximumsensitivity with 0.2/^V
graduated scale formeasurementsdownto-120dB.
b.Buttonselectionof JIS-A, DIN NOISE, DINAUDIO,
CCIR and CCIR/ARM weightingfiltersmake
possiblenoisemeasurementsandS/Nmeasurements
inaccordance with a varietyofstandards.
c. In addition toaveragedetectionandRMSdisplay,
DINand CCIR semi-peakdetection with RMS
displayisavailableformeasurementsinaccordance
with thosestandards.
d. ACOUTandDCOUTterminalsareprovidedto
facilitatewaveformobservation,recordingof
measured valuesoruseofthe unit asanamplifier.
e. A relativereferenceadjustment from 0 10dB
makes possiblerelativemeasurementsofsignals
with respecttoanarbitrarilysetreferencelevel,
particularlyusefulinS/Nmeasurement.
f.Anoverloadindicationpreventsmeasurementerrors
caused by distortion notdetectedbytheoperator
byviewingthemeterlevelforuse with the
weightingfilters.
2. FEATURES
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3.SPECIFICATIONS
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[Voltmeter Section]
Voltage ranges: > 10/A/-300V(10/A//30/<V/100M//
300M//1mV/3mV/10mV/30mV/
100mV/300mV/1V/3V /10V/30V/
100V/300V)fullscale
dB: -120~+50dB(0dB=1V)
dBm: -120~+52dBm(0dBm= 1mW/600O)
Displayaccuracy: With average detection in FLAT
mode:
10#Vand30/A/ranges: within
±5%offullscale
100/xV—300Vranges: within ±3%
offullscale
With quasi-peak detection and
DIN NOISE, DINAUDIOor
CCIR weighting filter:
W/AV range: within ±7%of
fullscale
30/tV~3G0V ranges: within ±5%
offullscale
Frequencyresponse: With average detection andRMS
display
10/iVrange:20Hz~10kHz±5%
10Hz~30kHz±10%
30/A/—300/A/ranges:
20Hz~20kHz±5%
10Hz~100kHz±10%
1mV~300Vranges:
20Hz~100kHz±3%
15Hz~300kHz±5%
10Hz~500kHz±10%
With quasi-peak detection and
RMS display
10/iVrange:30Hz~15kHz±5%
20Hz~20kHz±10%
10Hz~30kHz±20%
30/A/—300Vranges:
30Hz~20kHz±5%
20Hz-50kHz±10%
10Hz~100kHz±20%
input impedance: 1MO±5%
Parallelcapacitance:
50pFor less

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Overloadvoltagelevel: 10/A/—300/A/ranges:
AC 10Vrms,DC500V
1mV~300mVranges:
AC 80Vrms
500V(DC+ACpeak)
1V—300V ranges:
500V(DC+ACpeak)
Relative referenceadjustment:
0~approx.-12dB
Over level: Lightsuporflickerswhena
signalofmorethan+15dBfor
maximumvalueisapplied.
This indicates that thereisa
possibilityoferroneous
indication duetoover input
whena level weighting filter is
used.
Residual noise: Average detection :
10AV range input shorted, Input
equalityvalue
Below1.5M/rms(1.0/iVrmsTYP.)
30/iVrange, input shorted, Input
equalityvalue
Below5/iVs(3.0/A/rmsTYP.)
Peak detection :
10/A/ range input shorted, Input
equalityvalue
Below2.0/iVrms(1.0/iVrmsTYP.)
30M/range input shorted, Input
equalityvalue
Below5/iVrms(3.0/A/rmsTYP.)
Stability: Within ±0.5%offullscalefor
± 10% linevoltagefluctuation.
[AmplifierSection]
AC AMPLIFIER :
Gain : Approx.100dB
Output voltage: 1Vrms± 10%
Output resistance: 800O± 10%
Distortion : Below1%offullscaleat1kHz
This distortion isdeterminedby
theS/Nfortheranges10M/~
300/W
S/N : With respecttofullscale:
1mV~300Vranges:40dB minimum
300/^V range:30dB minimum
10U«Vrange:25dB minimum
30MArange:20dB minimum
*~'Vrange:16.5dB minimum

Frequency response: 1mV~300Vranges:
10Hz~500kHz within ±3dB
30/A/—300M/ ranges:
10Hz~150kHz within ±3dB
10/iVrange:
10Hz~30kHz within ±3dB
DC OUTPUT AMPLIFER :
Output voltage: 1V±10%forfullscale
Output resistance: 600O±10%
Frequency response: Approxthesameasthemeter
indication.
[Environmental]
coefficient: 0.08%/°Cor less
(at 1mVrangeormore)
Operatingtemperatureand humidity for within
specification: 15~35°C,80%RHmaximum.
Full operatingrange: 0~50°C,80%RHmaximum.
[PowerSupplySection]
Supplyvoltage: 100/117/220/240VAC ±10%
(Max. 250VAC)50/60Hz
Power consumption: Approx.15W
[Dimensions] Width 128mm,Height190(214)mm
^Depth285(315)mm
( ) dinsionsincludeprotrusions
from thebasic case.
[Weight] 4.6kg
[Accessories] Powercard1
Input cable(CA-41)1
Instructionmanual............1
-6~

4.CONTROLSANDINDICATORS
FRONT PANEL
© POWER (ONj>l/OFF* ) Switch
AC powerswitch.
®PowerLamp
IndicatestheVT-172ispoweredup.Lightswhen
POWER isdepressed.
(D RANGE SelectorSwitch
Attenuatorselectorswitch.16positionsin10dB
steps. Toprevent excessive inputs,thisswitchis
startedinthehighest,300Vrangeandgradually
workeddownrangetoprovideaneasilyreadable
meterdeflection.
®INPUT Juck
BNC signal input connector.
© RELATIVE REFControland© UNCALLamp
Sensitivityadjustmentanduncalibratedannunciator.
More than10dBofadjustmentispossible.When
the control isturned fully clockwise,thesetrange
is calibrated.This control canbeusedtoadjust
themetertoanappropriatelevelforrelative
measurements. - Whennotsetat fully clockwisethe
UNCAL lamplightstowarntheoperator.
Fig. 1 Frontpanelview
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® OVERLEVEL Lamp
Whenusingweightingfilterstheeffectofthe
filter istomask from theoperatorthepresence
ofanexcessively high input level.Thus distortion
andtheresultingerrorscanoccur without the
operatorbeingawareofthiscondition.Toprevent
thisthe OVERLEVEL warninglampalertsthe
operatorwhenthe input levelgoes+15dBabove
the full seal level (OdB). .
® AVERAGE/PEAK Switch
This switchisusedtoselectthedetectionmethod.
Inthereleased position averagedetectionand
RMS displayareineffect.Depressingtheswitch
selects eitherDINor CCIR quasi-peakdetection
andRMSdisplayofthesignallevel.When CCIR/
ARM isselectedthedetection method isauto-
maticallyswitchedtoaveragedetectionandRMS
displayregardlessofthe position ofthisswitch.
® WEIGHT Switch group
This six position selectionswitch group allows
selectionofoneof FLAT or JIS-A, DIN NOISE,
DINAUDIO, CCIR or CCIR/ARM weighted
response. Selectionofthe FLAT position turns
the unit into a widebandACvoltmeter.Ifno
button isdepressed,themodeisautomatically
CCIR/ARM.
JIS-A :
Used fornoiselevelmeasurementsinaccordance
with JSS:C1502A, JIS"C5551A, IEC-A, and IHF-A
standards.
DIN NOISE ;
Used fornoiselevelmeasurementsinaccordance
with DINstandard45405.
DINAUDIO: "
Used for1QHz~2.0kHz:.audiolevelmeasurementsin
accordance with DINstandard45405.
CCIR :
Used formeasurementsofnoiselevelinaccordance
with CCIR standards..
CCIR/ARM :
Used fornoiselevelmeasurementsinaccordance
with CCIR/ARM standards.
This measuringequipmentisrecommendedby
DolbyLaboratorie.
Whenthe CCIR/ARM filter isused,average
detectionisusedregardlessofthe AVERAGE/
PEAK switch.
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The appropriate AVERAGE/PEAK switchsettings
thevariousfiltersare:
for.
Filter : AVERAGE PEAK
JIS-A
O
DIN NOISE
-o
DINAUDIO o o
CCIR
-o
CCIR/ARM
o
® METER
® METER Zero-adjustTrimmer
Fig. 2 Rearpanelview
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REAR PANEL
©AC OUTPUT Juck
This output isusedforwaveformobservationor
forusedoftheVT-172asanamplifier.
@ DC OUTPUT Juck
This output isusedforrecording off-line measured
values.
®GNDTerminal
Groundconnection.
©AC POWER Connector
This isACpower input connector.Usethepower
cordprovided with the unit.
@ AC LINE VOLTAGE Selector
Set the plug ofthisselectortothelocalline
voltage(100/117/220/240VAC).
@ FUSE HoWer
Use a screwdrivertoopenthisholderfor
replacementofthefuseofspecifiedrating.
For 100or117V: 0.5A
For 220or240V: 0.3A
5.OPERATION
1. Checkthemechanicalzeroingofthemeter.
2. Connectthesignalcableto INPUT ©
3. Setthe RANGE switch® tothe300Vrange.
4. Connectthepowercordandpressthe POWER ®
switchto turn the unit ON.TheredLED©
should light indicatingthe unit isreadyforuse.
5. Input thesignaltobemeasuredandifnecessary
graduallyswitchtolower(moresensitive)ranges
until an easy toreadmeterdeflectionisobtained.
USING RELATIVE REF
To makemeasurements with respecttosomearbitrary
referencelevel, input thesignaltobeusedasthe
referencelevelanduse RELATIVE REF© to obtain a
OdB meterdeflection without changingthe RELATIVE
REF settingmeasurementofothersignalscanbemade
andreaddirectlyoffthedB scale indB with respect
tothereferencelevel.
The adjustmentrangeofthe RELATIVE REF control
is from 0 to-12dB(negativeonly)sotosetOdBfor
signalunderOdBswitchingdownrangemustbedone.
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