Kenwood FC-758 User manual

©PRINTEDINJAPANB50-7728-00(N)
26408
INSTRUCTION MANUAL
KENWOODCORPORATION
FREQUENCY COUNTER
FC-758
KENWOOD

CONTENTS
1. GENERAL••3
2.SPECIFICATIONS•••4
3„PRECAUTIONSFORUSE7
4.PANELEXPLANATION8
4-1FRONTPANEL8
4-2REARPANEL• 13
4-3CASESURFACE16
5.OPERATINGPROCEDURES17
6.MEASURINGCONSIDERATIONS26
7.MAINTENANCE• 28
2

1. GENERAL
The FC-758 isa multi-functional counter.Itcanbe
used tomeasureperiodsandtocounteventinputs(event
total count)aswellastomeasurefrequenciesofupto
1.3GHz.
The FC-758 counterhastwo input channels:ChannelA
andChannelB.
Channel A isdesignedasan input circuitterminated
with a 1.2Megaohmresistorandusedtomeasure
frequencies from 5 Hzto100MHz.
Channel B isdesignedasan input circuitterminated
with a BOohtnresistorandusedtomeasurefrequencies
from 80MHzto1.3GHz.
The FC-758 counter outputs measurementdatatoa
high-brightnessand 8—digit LEDdisplay.Itsdisplay
resolutionis0.1Hz(MAX.)atupto10MHz.The
display function enablesthe users tocontinuethere
datameasuringoperationsona 'LookandGo' basis.
Use ofthis product wouldbeanadvantageinmeasur-
ingthefrequenciesintherelativelylowfrequencyrange
because a periodmeasuring function (unit:microseconds)
andaneasily-controlledevent total count function are
supported. Note that thisevent total countcanbe
controlledexternally with rear-panelgatesignalor
through front-paneloperations.
The FC-758 isprovided with a self-checkfunction.
The function enablestheusertocheckandconfirm
majormeasurementfunctions.
The paneldisplay portion has several easy-to-use
LED displayfunctionssuchasa leading-zero
blankingfunction,measurement unit displayfunction,
gateactivemodedisplayfunction,andover-range
display(overflowindication)function.
The FC-758 uses a highlystablecrystaloscillatoras
its time base, The time base timercancontinuestable
oscillationevenwhenthepowersupplyvoltage
fluctuatesorinhardtemperatureenvironment.Asa
result,high-accuracymeasurementoperationsremain
unaffected.
The FC-758 counterhastheabovefunctions. This
means that itisa highlyfunctionalfrequencycounter
with high accuracyand that itcanhelpdevelopersand
designers aswellas production lineworkersand
servicingpersonnel with theirwork.
3

2. SPECIFICATIONS
[Frequency Measurement(ChannelA)]
MeasurementRange
kHz mode:5Hzto10MHz
MHzmode:5Hzto100MHz
Accuracy
±ReferenceTimeAccuracy
±1 count
Resolution
kHz mode:0.1Hzto100Hz
MHzmode: 1 Hzto1000Hz
CountingTime
(Gate Time)
0.01s, 0.1s,1.0s,10.0s
Unit
kHz, MHz
[ FrequencyMeasurement(ChannelB)J
MeasurementRange 80MHzto1.3GHz
Accuracy
±ReferenceTimeAccuracy
±1 count
Resolution
Prescale: 10Hzto10kHz
CountingTime
(Gate Time)
0.027s, 0.27s,2.7s,27s
Unit MHz
[PeriodMeasurement(A)]
MeasurementRange 0.285/<sto200ms(5Hzto3.5
MHz)
Accuracy
± 1 count± ReferenceTime
Accuracy ± TriggerError*
Resolution
100ps to 100 ns
Unit MS
Minimum Pulse
Width
142.5 ns
Magnification
(Gate Time)
X1, X10,x100,X1000
*[ TotalizeMeasurement(A)]
MeasurementRange
5Hz to10MHz
MaximumTotal
Count
0to99,999,999
Control Method
Reset/Hold control from the
flont panel.Alwaysactive
exceptforthe case wherethe
Start/Stop input terminallevel
is 'InActive(activehigh).
4

[input Characteristics(ChannelA)J
FrequencyBand
Width
5Hz to100MHz(Coupling:AC
coupling)
Sensitivity(sinewave) kHzmode:20mVr.m.s.
(5Hz to10MHz)
MHzmode:20mVr.m.s.
(5Hz to30MHz)
50mVr.m.s.
(30MHzto100MHz)
Impedance
40pF or less
Maximum Input
Voltage
125Vr.m.s. at400Hz
Attenuation
xl (1/1), x10(1/10)
Low Pass Filter
100kHz, -3dB
[ Input Characteristics(ChannelB)j
FrequencyBand
Width
80MHzto1.3GHz(Coupling: AC
coupling)
Sensitivity(sinewave) lOmVr.m.s.(80MHzto600MHz)
25mVr.m.s.(600MHzto1.0GHz)
50mVr.m.s.(1.0GHzto1.3GHz)
Impedance
50a
Maximum Input Voltage 1.5Vr.m.s.
[ReferenceOscillator]
OscillationFrequency
Crystal Oscillation10.0MHz
(Channel A : 5Hzto100MHz)
Crystal Oscillation3.90625MHz
(Channel B : 80MHzto1.3GHz)
Stabilization
(TenperatureFactor,
Aging Rate)
3x10 ~6/0to40°C(10.0MHz)
1X10'6/0 to40°C(3.90625MHz)
5x10"7/ Month (10.0MHz)
2X10"7/ Month(3.90625MHz)
[DisplayFunction]
Display
Eight-digit 7-segmentLED
DisplaykHz//*s,MHz, GATE,
OVER FLOW
FunctionsDisplay
kHz, MHz,CHB,PER, TOTAL,
CHECK
CountingTime
(Gate time)
CH A :0.01s,0.1s,1.0s,10s
CH B : 0.027s,0.27s,2.7s,27s
[Self-cheekFunction]
Display Displaya
count valueofthe
internal time base timer
(10.0MHz).
5

CountingTime
(Gate time)
0.01s, 0.1s,1.0s,10s
Resolution 0.1Hzto
100 Hz
[General RequirementsJ
Power Supply
Voltage
Power Comsunption
100/120/220/240V ± 10%(Max
250V), 50/60Hz,
20VA
Within Specifications
Temperatureand
Humidity
23°C±5°C,70%RH
OperatingTemperature
andHumidety 0°Cto40°C,80%RH
Dimentions
240(W)x64(H)xl90(D)mm
[Max.260(W)x70(H)x210(D)mm]
Weight
1 8kg
Accessories
InstructionManual1
Power SupplyCable1
Replacement Fuse 1
*Triggererroristyp[cal!y± 0.3%ofreadingdivided
bythenumberofcyclesaveraged,for input signals
havingbetterthan40dBS/N ratio andgreaterthan
lOOmVamplitude.
6

3. PRECAUTIONS FORUSE
a-
TurnofftheproductandthenconnectitwiththeAC
wall outletbyusingthe accessory powercablecord.
Refer tothemaintenancesectioninthisdocumentin
changing thecurrentpowersupplyvoltagetoa new
level.
b.Theuseofthisproductunderthefollowingambient
conditonsisstrictlyprohibited:
Direct exposuretothesunlight
High-temperatureandHigh-humidity
Mechanical Vibrationand ElectricalShock
c. Themaximuminputterminalvoltage levels ofthis
counterareasfollows:
(Front Panel)
Channel A Input Juck : 125Vrms(at 400Hz)
Channel B Input Juck : 1Vrms(at80MHzto1.36Hz)
(Rear Panel)
TOTALIZE INPUT START/STOP Input Juck : ±5V
d» This countercanstartitsoperationatthemoment
when powerisapplied.However,wait30minutesto
give ita warmandthenstartyourjobwithit.
Accurate measurementwillbe assured.
The counterisinitializedasfollowswhenturned
on:
FUNC switch: kHz/10MHzmode
GATE switch: 0.27s/0.01s
kHz/p- s display LED:Active
Notethatthedisplayindicates"0"ifnosignalisinput
tothecounter.
7

4. PANEL EXPLANATION
4-1FrontPanel
® POWER ON-—./QFFJB. Switch (See Figure1.)
The POWER ON JUL/OFFM switchisprovidedto
applypowertothiscounter.If pressed ( J«-), the
counterwillbeturnedon.Ifpressedagain(JKL),
thecounterwillbeturnedoff.
© GATE LED
© kHz/^s IndicatorLED
The kHz/i«sLEDindicatorisprovidedtoremind
theuserofthecurrentmeasurementdata unit.
This LEDindicatesthe unit ofthecurrent
measurementoperation.Ifthefrequencymeasurement
modehasactivated,itmeansthatthemeasurement
value is output inkiloherz.TheLEDindicatesthat
themeasurementvalueisdisplayedinmicroseconds
ifa periodisbeingmeasuredortheself-check
modeisselected.
®MHzIndicatorLED
The MHzLEDindicatorisprovidedtoremindthe
user ofthecurrentmeasurementdata unit.
This LEDturnsonwhenthefrequencymeasurement
value isdisplaedinMegaherz.
©DisplayLED
The displayconsistsof eight-digit LEDs
indicatingallthemeasurement values.
© OVER FLOW IndicatorLED
The OVER FLOW LEDisprovidedto notify the
user thatanoverflowhasoccurred.
This LEDblinkswhenanymeasurementdata
exceeds thedisplayrange.
© CHANNEL B(80MHzto1.3GHz)Inputjuck
The CHANNEL B input juckisa prescale input juck
providedtoallowobjectsignalstoenterthecounter.
Ifthefrequencyofgreaterthan100MHzismeasured,
thisjuckisusedasthe input juck. This juckis
terminated with a resistorof50ohm.
This input juckcanbeusedtomeasurethefrequencies
intherangebetween80MHzand1,300MHz
(1.3GHz).
This input juckcanbealsousedtomeasurethe
frequencies of less than100MHz.However,itis
recommendedthatChannelB beusedforthispurpose
8

Figure1.FrontPanel
3

because itsresolutionfunctionsbetterthanthe
channel A'sone.
® CHANNEL A(5Hzto100MHz)Input Juck
The CHANNEL A input juckisprovidedtoallow
objectsignalstoenterthecounter.
Ifthefrequencyof less than100MHzismeasured,
every kindofcycleismeasured,oreventinputs
are counted,thisjuckisusedasthe input.
This juckisa BNCconnectorterminated with a
resistor of1.2Megaohm.
Note:Ifa 50ohmsystemisconnectedtothis
counter,theChannelA Inputjuckneedstobe
terminated with a resistorof50ohm. Please keep
itinmind.
@ ATTx 10Switch
The ATT(enuation)x 10switchisprovidedto
enable theinternalATTenuatorcircuitoperation.
Ifthisswitchispressed(x10),the input signalto
channel A isattenuated into 1/10andthenreaches
thecounter.
Ifthisswitchispressedagain(x1),the input
signal tochannelA reachesthecounter without
attenuation.
Notethatthisswitchcanworktogether with
channel A onlybutdoesnotaffectchannelB.
®LPFSwitch
The LPFswitchisusedtoenabletheLow Pass
Filter circuitoperation.
Ifthisswitchis pressed(JUL), the input signalto
channel A isforcedtoentera low pass filter of
about100kHz.
Ifpressedagain( I,)fthe input signalreachesthe
counterdirectly. This LPFswitchdoesnotaffect
channel B.
© RESET Switch
The RESET switchisprovidedtoclearthecounter
into 0. This switchcanwork,independentlyofany
operationmodeselectedby FUNC switch(13).
Ifthisswitchispressed(thecounterwillbe
reset to0.
Ifthisswitchis released(JR.), a newmeasurement
willbestarted.
©HOLDSwitch
The HOLDswitchisprovidedtoperformvarious
operationsshownbelow.NotethattheHOLD
switchfunctionsdependonoperationalmodes
10

selected by FUNC switch@.
a. InanymeasurementmodeotherthantheEvent
Input TotalCountoperationmode:
Ifthisswitchispressed (JBL), thecurrent
measurementvalueindicatedbythedisplay LEDs
is 'held'andthecounterisreset.
Ifpressedagain (JHL), a newmeasurement will
bestarted.Thedisplayvaluebeing'held'isnot
until thenewmeasurementiscomplete.
b.EventTotalCounter (TOTAL/10 MHz) Mode :
Ifthisswitchispressed(_«&.),thecurrent
measurementvalueindicatedbythedisplay LEDs
is 'held'andtheevent total countisterminated.
Ifpressedagain(_•_),a newcountingoperation
will bestarted. Note that TOTALIZE INPUT
START/STOP input juck© shouldbe left 'Open'
beforethenewcountingoperationisstarted,
operationisstarted.
@ FUNC Switch/ModeIndicationLED
The FUNC switchisprovidedtoselectthedesired
operationalmode from theavailablemodes.
The Mode IndicationLEDisprovidedtoenablethe
user toseethemeasurementmodecurrentlyinuse.
The following operationalmodescanbeselected
with thisswitch:
a. kHz/10MHz(frequency)measurementmode
The kHz/10MHzmeasurementmodeisan
operationalmodeinwhichthisfrequency
countermeasuresthefrequencyofan input
signalto CHANNEL A.Themeasurementdata
will bedisplayedin'kHz'.
A desiredresolutionvaluecanbeselected with
GATE switch@ .
Note : Themaximumfrequencytobehandled
inthismeasurementmodeis10MHz.The
properrangeshouldbeusedaccordingto input
frequencies with eachrangecharaceristics fully
inmind.
b.MHz/100MHz(frequency)mode
The MHz/100MHzmodeisanoperationalmode
inwhichthiscountermeasuresthefrequencies
of input signalstochannelA and outputs the
measurementdatatothedisplaysection.They
are displayedinMegaHerz(MHz).
A desiredresolutionvaluecanbeselected with
GATE switch@ .
11

Note: Themaximumfrequencytobehandledin
thismeasurementmodeis100MHz.Theproper
range shouldbeusedaccordingtoinput
frequencies with each rangecharacteristicsfully
inmind.
c. CH B/1.3GHz (frequency prescale) mode
The CH B/OGHz modeisanoperationalmode
inwhichthisproduct measures thefrequenciesof
inputsignalstochannelB andoutputsthemto
thedisplaysection. They aredisplayedin
MegaHerz (MHz).
A desiredresolutionvaluecanbeselectedwith
GATE switch© .
d. PER/0.3j«s (PERIOD) mode
ThePER/0.3/*s modeisanoperationalmodein
which thisproduct measures the cycle timesof
inputsignalstochannelA andthenoutputs
themtothedisplaysection. They aredisplayed
inmicroseconds.
A desiredresolutionvaluecanbeselectedwith
GATE switch© .
e. TOTAL/10 MHz(eventinput total count)mode
The TOTAL/10 MHzmodeisanoperationalmode
inwhichthisproductcountsthenumberof
channel A input cycles andthenoutputs each
countvaluetothedisplaycontinuously.
This cycle countanddisplayoperationscanbe
externally controlledwiththegatesignalinput
tothe TOTALIZE INPUT START/STOP input
juck ontherearpanelorthe HOLD switch
onthe front panel,
f. CHECK/10MHz Mode
The CHECK/10MHz modeisanoperationalmode
inwhichthisfrequencycounter checks internal
functions. Ifthisself-checkmodeis selected, the
frequency oftheinternaltime base timer(10MHz)
willbedisplayedbythe 8—digit 7-segment LEDs.
Look atthedisplayvaluetoseeifthisproduct
operates normallyornot.
A desiredresolutionvaluecanbeselectedwith
GATE switch@ .
@ GATE Switch/GATE LED
TheGATE switchisprovidedtoselecta desired
display resolutionvaluefortheperiodmode
(PER/0.3us) orthefrequencymode(MHz/100MHz,
kHz/10MHz, orCH B/1.3GHz) startedby FUNC

switch@ .
The GATE LEDisprovidedtoindicatethe
counteriscurrentlyactive.
Iftheswitchispressed,a newdisplayresolution
value isselected.Thisoccursevery time whenthe
switchispressed.Thereare four displayresolution
values available.Theyare:
0.01s, 0.1s,1s,10sforChannelA
0.027s, 0.27s,2.7s,27sforChannelB
Resolution
value
0.027s
0.27s
2.7s
27s
Resolution
value
0.01s 0.1s
1.0s 10s
Magnification
xl
xlO
X100
X1000
4-2 Rear Panel(SeeFigure2.)
© TOTALIZE INPUT START/STOP Input juck
The TOTALIZE INPUT START/STOP input juckis
providedto control theevent input countoperation
mode.
The event input countoperationisenabledifthe
input signaltothisjuckbecomesactive(TTLlevel:
'H').
The event input countoperationisforcedto
terminateifthe input signaltothisjuckbecomes
inactive(TTLlevel: 'L').Theevent input count
operationisalsodisabledifthisjuckisgrounded
tothe chassis ground.
13

Figure 2.RearPanel
14

@ Powersupplyvoltageselector (LINE VOLTAGE
SELECT)
The powersupplyvoltageselectorisprovidedto
select thesupplyvoltage that isappliedtothe
counter.
When youchangethecurrentsupplyvoltage,
refer tosection7-1'Maintenance'.
©Power input connector
The power input connectorisprovidedfor
connectinga powercordtothecounter.Usethe
accessory powercord.
@ Fuse Holder
The fuseholderisprovidedtoenabletheuserto
set a protection fuseinthecounter.
For the100V-or120V-powerrequirement,use
the0.25A/250Vslow-blowtype fuse.
For the220V-or240V-powerrequirement,use
the0.125A/250Vslow-blowtype fuse.
When youreplacethecurrent fuse, refertoChapter
7 'Maintenance'.
15

4-3 Case Surface
@ Thereisanopeningonthe case surfacetoenable
theusertofine-adjustthe TCXO
(standardoscillator).
This adjustmentappliesto both oftheCHA
(10.0MHz) andCHB (3.90625MHz)channels.
The openingisnormallycovered with a rubbercap.
Iftheoscillatorneedstobefineadjusted,please
contactyourdealerrepresentative.
Figure 3. Case Surface
16

5.OPERATING PROCEDURES
Every timewhenyoustartusingthe FC-758 Multi-
FunctionalCounter,lookattherearpanelandverify
thatthepowersupplyvoltageselectorsetting
indicatesthelevelofthesupplyvoltagetobeactually
applied.
1) Connectthe accessory powercord with thepower
input connector(inlet)oftherearpaneland
inserttheACplug into thenearby outlet.
2) Press the POWER switch( JHL). Thecounterwillbe
turnedon.
3) Read carefullyChapter3 ' Notesonuse'(onpage7)
tohandlethisinstrumentcorrectly.
5-1FrequencyMeasurement
5-1-1. FrequencyMeasurement with ChannelA
(5Hz to100MHz)
(1) Inputa targetsignal(tobemeasured)to CHANNEL
A input juck®.
(2) Select eitherthekHz/10MHzmodeorMHz/100MHz
modebyusing FUNC switch@). kHz/^s LED(3)
orMHzLED® willbeturnedon.
Note: Themaximumallowablemeasurement
frequency varies dependingonthemeasurement
modes. InthekHzmeasurementmode,upto
10MHz-frequencycanbeprocessedwhilethe
maximumfrequencythatcanbehandledinthe
MHzmodeis1.3GHz.
(3) Select a desireddisplayresolutionvalue with
GATE switch© .
(4) Thefrequencyofthe input signalcurrentlybeing
measured willbe output toDisplay©.
GATE LED© blinksduringthemeasurement.
The measurementvalueonthedisplaywillbe
updatedatthemomentwhenonemeasurement
intervalisover(whenthe GATE LEDbecomes
inactive).
(5) Press ATTx 10switch (JBL.) accordingto input
signal levels. Iftheinternalattenuatorcircuitis
enabled, input signaltothe CHANNEL A pinis
attenuated into 1/10beforereachingthecounter.
This attenuatesnoise-superimposed input signals.
Inaddition,theattenuationcircuitpreprocessesa
signal with rathera highamplitude into a
reasonable level. Asa result,accuratecounting
is assured.
17

(6) Press LPF(low pass filter)switch© ( JL) to
eliminatenoisesignalcomponents.Iftheinternal
LPF circuit function isenabled,the input signal
tothe CHANNEL A juckishandledfirstbythe
LPF circuit(about100kHz)andthen input tothe
counter.Therefore,thecounterprocesses input
signals without high-frequencynoisesonly.Asa
result,accuratelow-frequencymeasurementis
assured.
(7) IfHOLDswitch© ispressed during frequency
measurement,thecurrentmeasurementvalueon
theDisplayisheldasitis.Iftheswitchisreleased,
a newmeasurementcycle will bestarted.However,
themeasurementvaluecurrentlybeingdisplayed
will remainunchanged until thenewmeasurement
cycle iscomplete.Thatis,thedisplayvaluebeing
heldbytheHOLDswitchisupdatedbythe output
value from thenewmeasurementoperation.
(8) If RESET switch@ ispressed during frequency
measurement,themeasurementvalueonthe
Display will beresetto'0'.Ifpressedagain,a
newmeasurementcycle will bestarted.However,
themeasurementvalue will remain'0' until the
newcycleiscomplete.
5-1-2. FrequencyMeasurement with CHANNEL B
(80MHzto1.3GHz)
(1) Input a targetsignal(tobemeasured)to
CHANNEL B prescale input juck®.
Note : Themaximum input voltagetothisjuckis
1 Vrmsandits input impedanceis50ohm.ATTx
10 switch® cannotworktogether with thisjuck.
(2) SelecttheCHB/OGHzmode with FUNC switch
(3) Selecta desireddisplayresolutionvaluebyusing
GATE switch@ .
(4) Thefrequencyofthe input signalcurrentbeing
measured will be output toDisplay©.
GATE LED(2)blinks during thefrequency
measurement.
The measurementvalueindicatedbytheDisplay
will beupdatedatthemomentwhenone
measurementcycleiscomplete(whenthe GATE
LED becomesinactive).
Note : Itmayhappentooccur that measurement
is delayedorthedisplayisunstable.Inthis case,
refertosection5-4' DisplayDescription'.
18

(5) IfHOLDswitch© ispressed during frequency
measurement,thecurrentmeasurementvalueon
theDisplayisheldasitis.
Ifpressedagain,a newmeasurementcycle will
bestarted.However,themeasurementvalue
currentlybeingdisplayed will remainunchanged
until thenewmeasurementcycleiscomplete.
That is,thedisplayvaluebeingheldbytheHOLD
switchisupdatedbythe output value from the
newmeasurementoperation.
(6) If RESET switch© ispressed during frequency
measurement,themeasurementvalueonthe
Display will beresetto'0'.
Iftheswitchisreleased,a newmeasurement
cycle will bestarted.However,themeasurement
value will remain'0' until thenewcycleis
complete.
(7) ATTx 10switch® andLPFswitch© are
helpless intheprescale input mode.
5-2PeriodMeasurement
Intheperiodmeasurementmode,thecycle time of
each input signalismeasured.
The cycle time finally output bythecounteristhe
average ofallthe cycles measured.Thenumberof
cycles tobemeasuredcanbe1,10,100or1000.
The maximum input frequencyis3=5MHz.
(1) Input a targetsignal(tobemeasured)tothe
CHANNEL A input juck.
(2) Selectthe PER/0.3us (period)mode with FUNC
switch@ .
The kHz/^s LED will turn onindicating that the
measurementvalueisdisplayedinmicroseconds.
(3) Selecta desireddisplayresolutionvalue with
GATE switch@ . This GATE switchisusedto
specifythenumberof cycles percyclemeasurement.
As alreadyexplained,thefinalcycle time output
is theaverageofallthecycletimes.Thedisplay
resolution LEDs (fromtheleft)indicates1,10,
100 and1000.
(4) Theaveragecycle time ofalltheperiodsmeasured
is output toDisplay©.
GATE LED® blinks during theperiodmeasurement.
The measurementvalueonthedisplay will be
updatedatthemomentwhenoneperiodmeasurement
is complete(whenthe GATE LEDturnsoff).The
GATE LED blinking maynotbeconfirmedbecause
19

itgetstoofastduetohigh-frequencysignal
measurement.
Note : Itmayhappentooccur that measurement
is delayedorthedisplayisunstable.Inthis case,
refertosection5-4' DisplayDescription'.
(5) Press ATTx 10switch(_•*.)accordingto input
signallevels.Iftheinternalattenuatorcircuitis
enabled, input signaltothe CHANNEL A juckis
attenuated into 1/10beforereachingthecounter.
This attenuatesnoise-superimposed input signals.
Inaddition,theattenuationcircuitpreprocessesa
signal with rathera high amplitude into a reasonai
level. Asa result,accuratecountingis assured.
(6) Press LPF(low pass filter)switch<© (-ML) to
eliminatenoisesignalcomponents.Iftheinternal
LPF circuit function isenabled,the input signalto
the CHANNEL A juckishandledfirstbytheLPF
circuit(about100kHz)andthen input tothe
counter.Therefore,thecounterprocesses input
signals without high-frequencynoisesonly.Asa
result,accuratelow-frequencymeasurementis
assured.
(7) IfHOLDswitch© ispressed during period
measurement,thecurrentmeasurementvalueonthe
Display isheldasitis.Ifpressedagain,a new
measurementcycle will bestarted.However,the
measurementvaluecurrentlybeingdisplayed will
remainunchanged until thenewmeasurementcycle
is complete.Thatis,thedisplayvaluebeingheld
bytheHOLDswitchisupdatedbythe output
value from thenewmeasurementoperation.
(8) If RESET switch© ispressed during period
measurement,themeasurementvalueontheDisplay
will beresetto'0'.
Iftheswitchisreleased,a newmeasurementcycle
will bestarted.However,themeasurementvalue
will remain'0' until thenewcycleiscomplete.
5-3Event-InputTotalCountMeasurement
IntheEvent Input Totalmeasurementmode,the
total numberofeventsgenerated during a fixed
certainperiodismeasured. This measurement
periodcanbesetbyusingthe front panelswitch
ortherearpanelgatesignal input juck.
The signal input circuitandthecounterare
coupled with capacitance(AC),whichrequires
atleast5 eventspersecondtobegenerated.
20