Kenwood VT-173 User manual

KENWOOD
©PRINTED II.PAN
AUTORANGEVOLTMETER
VT-173
INSTRUCTION MANUAL
KENWOODCORPORATION

CONTENTS
1. GENERAL3
2. FEATURES 3
3. SPECIFICATIONS4
4.FUNCTIONALCONTROLS6
5.OPERATION8
6.APPLICATIONS11
7. MAINTENANCE13
8.ALIGNMENT14
9.CAUTIONSFORUSE• 16
-2-

! GENERAL
The KENWOOD ElectronicVoltmeter VT-173 isan
absolute-mean valueindicationtypeautomaticelectronic
voltmeterwhichcanmeasureACvoltagerangingfrom
10Hz to1MHzontheroot-mean-squarevalue scale.
Ithasa wide full scale rangescoveringfrom1mVto
300V and selects theoptimummeasurementrange
automaticallyinaccordancewithinput level.
The measurementrangecanbefixedmanually.Foron-
production-lineuse,a remotecontrolunit(option)is
available.
2. FEATURES
a. Dualpowerdifferentialinputamplifiersusedinthe
entirecircuitprovidea highreliabilityandgood
characteristic ofrestorationfrompossiblesaturation
dueto excessive inputs.
b.A large-sizedTaut-bandmeterhasa highsensitivity
and reliability.
c. Thenumberofadjustingtrimmersareminimized
withtheuseoftheamplifierswhichareprecisely
calculated intheopen loop gainsandarenegative-
biased throughmetal-filmresistorsasaccurateas 1 %.
The amplifiercharacteristics,therefore,arefreefrom
any secular change.
d. Theinputresistanceisashighas 10 Milinall
ranges anditsparallelcapacitanceis 45pF orlower.
e. Themeter scales aregraduatedintheroot-mean-
square values forsinusolidal waves. Also, themeter
has a dBanddBm scales convenientformeasuring
relative values.
f.The output terminalallowsyour VT-173 touseasa
high-gain,wide-bandamplifier.
-3-

g. Anelectroniccircuitautomaticallyselectstherange
mostsuitableformeasuring input voltage.
A desiredrangecanalsobeselectedmanually.
h.ACandDC outputs areavailablefor monitoring.
3. SPECIFICATIONS
-4-
[ Meter Section]
Measurablevoltages: 1mV-300mVin12ranges:1mV,3mV,
10mV,30mV,100mV,300mV,1V,3V,
10V, 30V,100V,and300V full scales.
dB : -80~+50dB(0dB=1V)
dBm: -80~+52dBm(0dBm=1mW,60012)
Error : Within±3%of full scale at1kHz.
Frequency response: ±10%at10Hz~1MHz,
±3% at20Hz-200kHzand
±2% at50Hz-100kHzas
referencedto 1 kHzresponse.
Input impedance: 10MO±5%, with less than45pF
parallelcapacitance.
Durable input voltage: 500V (DC-f AC peak)1Vto300Vrange
100V (DC+ACpeak)
1mVto300mVrange
Stability: Within±0.5%of full scale for
±10%linevoltagefluctuation.
Residual voltage: Less than20^V with
input shortedon1mVrange

[PowerSupplySection]
Line voltage: 100,120,220VAC±10%
216-250 V AC, 50/60Hz
Power consumption : Approx,5W.
[ Dimensions ] 128(130)Wx190(215)Hx238(270)Dmm.
Valuenin( ) includeprotrusions.
[Net weight ] 3.2kg
[Accessories]
Powercable: 1 pc.
Input cable: CA-41, 1pc.
Replacementfuse: 0.3A2 pes.0.5A2pes.
Instruction manual: 1 copy.
-5-
[AC output AmplifierSection]
Output voltage: 1Vrms±20%
Output resistance: 60012±20%
Frequencyresponse: Within ±3dBat10Hz-500kHz.
Distortion : Less than 1%at full scale.(Rated
bysignal-noise ratio in 1 mVrange.)
Signal-to-noise ratio : Over40dBat full scale.
[DC Output AmplifierSection]
Output voltage: 1V±20%4-offsetvoltageat
fullscale
Offsetvoltage: ±100mV
Output resistance: 60012±20%
Ripple: Less than 10mVrms
Frequencyresponse: Within ±3dBat10Hzto1MHz
[ Environmental]
Temperature
coefficient: ±0.08%/°C
Within specifications
tenperature: 10—40°C
Full operating
temperature: 0~50C
Relative humidity : Less than 80%

4.FUNCTIONAL CONTROLS
Front Panel(seeFigure1 )
Figure 1 - Front Panel View.
REFER-
ENCE No.
IDENTIFICATION
DESCRIPTION
® ON/OFF
ON/OFF switch
-INPUT
Input connector
©
AUTO/HOLD
Mode selectorswitch
® DOWN
Range DOWNswitch
©
UP
Range UPswitch
©
AC OUTPUT
AC output terminalctor
®
RELATIVE REF
RELATIVE REF
controller
®
UNCAL
Uncaliblationindicator
®
VOLTES/DECIBELS Meter
RANGE RANGE
indicatorlamp
©
METER zero-adjust
trimmer
-6-

Figure 2 - Rear Panel View.
Figure 3
Figure 4
_7_

Rear Panel(seeFigure2 )
REFER-
ENCE No.
IDENTIFICATION
DESCRIPTION
@
Power connector
©
Line voltageselectoi
andfuseholder
®
DC OUTPUT
DC output terminal
©
CONT. INPUT Remote
control connec-
tor(option) blind plate
5.OPERATION
The VT-173hasthreerangesettingmodes; Auto,Hold
andRemote(option). With thesemodes,theVT-173
providesa wideapplications.
[HowtoUseAuto Mode]
(1) Bypressingthe ON/OFF switch®,the RANGE
indicatorlamps© goonsequentially from 300V
rangeindicator.The1mVindicatorgoesonfinally.
(2) Whensignalis input totheINPUTconnector®,
theVT-173automaticallyselectsthemeasurement
rangewherethemeter pointer indicatesa value
from 27%to102%ofthe full scale (standard
value ).
(3) Ifthelevelofthe input signalcorrespondstoa
value from 85%to102%ofthe full scale (standard
value), a 1 levelhigherrangemaybeselectedto
indicatethevoltage within 27%to32%(standard
value). Insucha case, thesensitivitycanbe
increased by1 range with theDOWNswitch@ to
indicatethevoltage within 85%to102%(standard
value).
Note:The "full scale" denotesthedivision10on
the scalr"
Preset ControlesonSidePanel(seeFigure3 and4 )
REFER-
ENCE No.
IDENTIFICATION
DESCRIPTION
©
TC 101
First Attenuatorpreset
trimmercapacitor
©
VR 101
First Attenuatorpres.
variableresistor
VR 102 Meterfullscalepreset
variableresistor
©
VR 201
Range uplevelpreset
variableresistor
VR 202
Range downlevelpreset
variableresistor
_8_

(4) Tofixtherange,settheMODEselectorswitch©
toHOLDposition.Therangeimmediatelybefore
settingtheselectorswitchisheldhereafter.
[HowtoUseHoldMode]
(1) Press the ON/OFF switchCDtofixindicationof
the RANGE lamps© to300V.
(2) Supplysignaltothe INPUT connector®.
(3) Whileobservingtheswingofthemeter pointer,
select a desiredrange with theDOWNswitch®.
(4) Theselectedrangeischanged into the1 level
higherrangebypressingtheUPswitch© orthe
1 levellowerrangebypressingtheDOWNswitch®.
[Scale (SeeFig.5)]
(1)Voltage Scale
The meterhasdouble-graduatedblack scales: the
scale © graduated from 0 to10andthe scale ®
graduated from 0 to3.Inthe1Vrange,division
10 onthe0—10 scale @ indicates1V.Inthe
300mVrange,division3 onthe0~3 scale ®
indicates300mV. Scales correspondtovoltages
likewiseinotherrancje.
(2)dB Scale
The dB scale, marked with dBVingeneral,
indicates1VasOdB.The0—10 scale © has
voItage-ratio-baseddivisionsanddivision10onit
correspondstoOdB.
Ifthemeterreads-6dBinmeasurementusingthe
20dB (10V)range,themeasuredvalueis20dB-6dB
= 14dB. This correspondencealsoappliestoother
ranges.
(3)dBm Scale
Ingeneral,voltmetershavea referenceleveldivision
ofOdBmequalto0.775V(1mVpower)induced across
a 6000resistanceload.Therefore,thereddBm scale
is availabletomeasurea powerlevelreferencedto0
dBm, with theimpedanceofthegivenpowercircuit
being600Opureresistance.Wheremeasured across
specific resistanceloads,forexample,10kll,other
thanthe600Oload,thelevelsaresometimes
expressed indBs.
-9-

[HowtoUseRelativeReferenceControl]
The RELATIVE REF control iskeptat"CAL"in
general cases ofreadingcalibrated,absolutevalueson
theMeter.Tomeasurerelativelevelssuchasfre-
quencyresponses, turn the control foruncalibration
state(UNCAL) until thereferencelevelissettoa
desiredvalue,forexample,OdBm.Thisallowsreading
therelativelevels.
[HowtoUseRemoteControl]
The RT-61 option, oneofthefeaturesofthe VT-173,
providestheVT-173 with remote control capability.
To attachthe RT-61, removethe blind plate from
therearpanelofthe VT-173, installtheconnector
supplied with the RT-61, then plug theRT-61 into
theconnectoronthePCB(voltmeterunit).
-10-
Then, settheMODEselectorswitchontheremote
control boxto REMOTE position.Bythis,the
measurementrangesoftheVT-173canberemote-
controlled with the RANGE selectorontheremote
control box.BysettingtheMODEselectoronthe
remote control boxto PANEL, theVT-173canbe
operatedonthepanel.
For details,seetheInstructionManualofthe RT-61.
Note:TousetheVT-173intheRemotemode,be
sure tosettheMODEselectoronthepanel
toAUTOposition.
[HowtoUseACOUTPUTandDCOUTPUTConnectors]
The AC OUTPUT connector outputs 1VrmsAC
voltagewhenthemeterreadsthe full scale,
regardless ofthemeasurementrange.
Output impedanceis600O.
Likewise, theDC OUTPUT connector outputs approx.
1V DCvoltagewhenthemeterreadsthe full scale,
regardless ofthemeasurementrange.
Output impedanceis600O.
Figure 5 - Meter Scale Graduations.