Kenwood FC-757 User manual

©PRINTED IN*NB50-7726-00(N)
06106
UNIVERSALCOUNTER
FC-757
INSTRUCTION MANUAL
KENWOOD CORPORATION
KENWOOD

CONTENTS
1. GENERAL. ....3
2.SPECIFICATIONS4
3." PRECAUTIONSFORUSE7
4.PANELEXPLANATION8
4-1. FRONTPANEL8
4-2.REARPANEL15
4-3.CASESURFACE18
5.OPERATINGPROCEDURES19
6.MEASURINGCONSIDERATIONS34
7.MAINTENANCE39
2

1. GENERAL
The FC-757 isa universalcounter.Itcanbeusedto
measure frequencies(175MHzMax.),period,frequency
ratio, total number,andtimeinterval.Eventinputs
can bealsocounted with thecounter.
Channel A isan input channelterminated with a
resistor of1.2MOandusedtomeasurethefrequencies
between5Hzand175MHz,periodandthe total number
ofeventinputs.
Channel B isan input channelterminated with a
resistor of1.2MI2andusedtomeasurefrequencyratio
andtimeinterval.Thesignalsintherange from
5Hz to2MHzcanbe input.
The FC-757 universalcounterhasan 8-digit high-
brightnessLEDdisplay.Thehighestdisplayresolution
is 0.1Hz.
The FC-757 isa highlyfunctionaladvanceduniversal
counter with the following functions.
-Periodmeasurementfunction
The periodmeasurementfunctionisusedtomeasure
theperiodofeach input signal. This functionwould
output higher-precisionmeasurementdatainrelatively
lowfrequencyoperationmode.
—Timemeasurementfunction
The timemeasurementfunctionisusedtomeasure
theintervaltimebetweenanytwoedgesof
differenttwosignals,andbetweentwo'single-shot'
pulse signals.
-EventInput total countmeasurementfunction
The event input total countmeasurementfunction
is usedtomeasurethe total numberofeventinputs
tothecounter. This functioncanbecontrolled
through paneloperationsorby inputting gate
signais externally.
Inaddition,the FC-757 universalcounterhasa
self-check function.Withthischeckfunction,major
measurementfunctionscanbetested.
The displayfunctionsupportsa leading-zeroblanking
andconsistsofmany LEDs indicatinga measurement
unit, gateactivityandoverflowoccurrence.
The FC-757 multi-functionalcounterhasa highstable
crystal oscillatorasthetimebaseclockgenerator.
Therefore, highaccuracymeasurementisnotadversely
affectedbyfluctuationsintemperatureandpower
supplyvoltage.
3

2. SPECIFICATONS
[Frequency Measurement(ChannelA)]
Measurementrange
kHz mode: 5Hzto10MHz
MHzmode: 5Hzto175MHz
Accuracy
±Reference time accuracy±1
count
Resolution
kHz mode: 0.1Hzto100Hz
MHzmode: 1Hzto1000Hz
Counting time
(Gate time)
kHz : 0.01s,0.1s,1.0s,10s
MHz: 0.02s,0.2s,2.0s,20s
Unit
kHz, MHz
[PeriodMeasurement(A)]
Measurementrange 0.5j«sto200ms(5Hzto2MHz)
Accuracy
±1 count± reference time
accuracy ± trigger error*!
Resolution
100ps to100ns
Unit
ms, ^s
Minimum pulse width
250ns
Magnification
(Gate time)
x1, x10,x100,X1000
[Frequency RatioMeasurement (A/B)]
MeasurementrangeA
5Hz to10MHz
MeasurementrangeB
5Hz to2MHz
Denominator
magnification DenominatormagnificationN :
x1, x10,X100,X1000
Accuracy
^F^AXN)
±TRI99ER ERR°R
N: magnification
[TimeIntervalMeasuement(AtoB)J
Measurementrange 0.5j«sto200ms(5Hzto2MHz)
Resolution
100ps to100ns
Accuracy
± 1 count± Reference time
accuracy ± Triggererror±N
Minimum pulse width
(A toB)
250ns
Unit
ms, f*s
Magnification
x1, X10,x100,X1000
4

Single-shotpulse
processing Waitbyreset
[Event input TotalMeasurement(A)]
Measurementrange
5Hz to10MHz
Maximum total count
0to99,999,999
Control
Reset/Hold control from the
front panel.Alwayactive
exceptforthe case wherethe
Start/Stop input terminal level
is 'InActive(activehigh).
[Input Characteristics(channelA)]
Frequencyband width
5Hz to175MHz
(Coupling: ACcoupling)
Sensitivity(sinewave) kHz
mode :
20mVr.m.s.(5Hzto10MHz)
MHz mode :
50mVr.m.s.(5MHzto125MHz)
100mVr.m.s.(125MHzto150MHz)
150mVr.m.s.(150MHzto175MHz)
Impedance
1.2MO, 40pFor less
Maximum input voltage
250Vr.m.s. at(5Hzto60Hz)
Attenuation
x1(1/1), x10(1x10)
Low pass filter
10kHz,-3dB
slope +/—selectable
Triggerlevel Presetableorvariable
(about± 1V)
[Input Characteristics(ChannelB)]
Frequencyband width
5Hz to2MHz
(Coupling: ACcoupling)
Sensitivity(sinewave) 30mVr.m.s.
Impedance 1.2MO,40pFor
less
Maximum input
voltage
125Vr.m.s. at(5Hzto60Hz)
Attenuation
X1 (1/1), X10(1/10)
Slope +/-selectable
[ReferenceOscillator]
Oscillationfrequency 10.0MHz(5Hzto175MHz)
5

Stabilization
(Tenperature factor,
agingrate)
3x10-6/0 to40°C
5x10'7/month
[Reference FrequencyInput]
Frequency
10MHz
Inputsensitivity
1.77Vr.m.s. or less
Coupling
AC
Inputimpedance
540O
[Display Function]
Display
Eight-digitLEDdisplay
kHz/^s, MHz/ms, GATE,
OVER FLOW
Functions display
FREQ, PER, RATIO, TI(AtoB),
TOTAL, CHECK
Countingtime
(Gate time)
0. 01s, 0.1s,1.0s,10s
1, 10,100,1000
[Self-check Function]
Display Display
a countvalueofthe
internaltime base timer
(10.0MHz)
Countingtime
(Gate time)
0.01s, 0.1s,1.0s,10s
Resolution
0.1Hz to100Hz
[General Requirements]
Power supplyvoltage
100 / 120/ 220/ 240VAC±10%
(max.250V), 50/60Hz
Power comsunption
20VA
Withinspecifications
temperatureand
humidity
23°C±5°C, 70% RH
Operatingtemperature
and humidity
0°Cto40°C, 80%RH
Dimentions
240(W)x64(H)x190(D)mm
[max. 260(W)x70(H)x210(D)mm]
Weight 1.8kg
Accessories
Instructionmanual1
Power supplycable1
Replacement fuse1
*iTriggererroristypically±0.3%ofreading
dividedbythenumberof cycles averaged,for
input signalshavingbetterthan40dBS/N
'ratioandgrcr than100mVamplitude.
6

3. PRECAUTIONS FORUSE
a. Turnofftheproductandthenconnectitwith
theACwalloutletbyusingthe accessory power
cable cord.
Refer tothemaintenancesectioninthisdocument
inchangingthecurrentpowersupplyvoltageto
a newlevel
b.Theuseofthisproductunderthefollowing
ambientconditionsisstrictlyprohibited:
Directexposuretothesunlight.
High-temperatureandHigh-humidity.
Mechanical vibrationandElectricalshock.
c. Themaximuminputvoltagelevelsofthis
counterareasfollows.
(Front panel)ChannelA Inputjuck:
250Vrms (5Hzto 60Hz)
(Front panel)ChannelB InputjUck:
125Vrms (5Hzto 60Hz)
(Rear panel) TOTALIZE START/STOP
Inputjuck: ±5V
(Rear panel)EXT.INinputjuck: 10Vrms
d. This countercanstartitsoperationatthe
momentwhenpowerisapplied.However,wait
30 minutestogiveita warmandthenstart
yourjobwithit.Accuratemeasurementwillbe
assured.
7

4. PANEL EXPLANATION
4-1 Frontpanel
® POWER ON-—-/OFF JBL Switch
The POWER ON/OFF switchisprovidedto
applypowertothiscounter.If pressed(_•*.),
thecounterwillbeturnedon.Ifpressedagain
(JHL), thecounterwillbeturnedoff.
© GATE Indicator(LED)
(3) kHz/^s Indicator(LED)
The kHz/^s LEDindicatorisprovidedto
remindtheuserofthecurrentmeasurement
data unit.
This LEDindicatesthe unit ofthecurrent
measurementoperation. This LEDremains
active aslongasthemeasurement unit isnot
changed with themeasurement unit selectswitch
(not pressed).
Ifthefrequencymeasurementmodeortheself-
check modeisactivated,thisindicatormeans
thatthemeasurementvalueis output inkiloherz.
The LEDindicatesthatthemeasurementvalue
is displayedinmicrosecondsifa periodortime
intervalisbeingmeasured. This LEDindicator
becomes inactivewhenthefrequencyratio meas-
urementmodeortheevent total countmeasure-
mentmodehasbeenstartedup.
©MHz/msIndicator(LED)
The MHz/msLEDindicatorisprovidedto
remindtheuserofthecurrentmeasurement
data unit. This LEDbecomesactiveaslong
as themeasurement unit ischanged with the
measurement unit selectswitch(pressed).
Ifthefrequencymeasurementmodeortheself-
check modeisactivated,thisindicatormeans
thatthemeasurementvalueis output inmega-
herz. TheLEDindicatesthatthemeasurement
value isdisplayedinmillisecondsifa periodor
timeintervalisbeingmeasured.
This LEDindicatorbecomesinactivewhenthe
frequencyratiomeasurementmodeortheevent
total countmeasurementmodehasbeen
startedup.
8

Figure 1.Frontpanel
9

©Display(LED)
The displayconsistsof eight-digit LEDs
indicatingallthecurrentmeasurementvalue.
© OVER FLOW Indicator(LED)
•The OVER FLOW LEDisprovidedto notify
theuserthatanoverflowhasoccurred.
© CHANNEL B (5Hzto2MHz)InputjUck
The CHANNEL B input juckisprovidedto
allowobjectsignalstoenterthecounter.
This juckisusedforfrequencyratiomeasure-
mentandtimeintervalmeasurement.
The CHANNEL B input juckisa BNCconnector
terminated with a resistorof1.2megaohm.
The maximum input voltageis125Vrms.
©ATTx 10Switch
The ATT(enuation)x 10switchisprovidedto
enable theinternalATTenuatorcircuit
operation.
Ifthisswitchispressed(x10),the input
signal tochannelB isattenuated into 1/10and
thenreachesthecounter.
Ifthisswitchispressedagain( x 1 ),the input
signal tochannelB reachesthecounter without
attenuatjon.
Notethatthisswitchcanworktogether with
channel B onlybutdoesnotaffectchannelA.
© -SLOPE Switch
The -SLOPE switchisprovidedtopermitthe
user toselectpositive-goingedgeornegative-
going edgeofthe CHANNEL B signalfor syn-
chronization.
Ifthisswitchispressed(m),negative-going
edgewillbeselectedforsynchronization.
Ifthisswitchispressedagain (JUL), positive-
going edgewillbeselectedforsynchronization.
© CHANNEL A (5Hzto175MHz)Inputjuck
The CHANNEL A input juckisprovidedtoallow
signals tobe input tothecounterforfrequency
measurementandperiodmeasurement.
Inthefrequencyratiomeasurementmode,the
ratiobetweenthe CHANNEL B inputsandthe
CHANNEL A inputsismeasured.
Inthetimeintervalmeasurementmode,the
differenceintimebetweenthe CHANNEL B
inputsandthe CHANNEL A inputsismeasured.
The CHANNEL A input juckisa BNCconnector
10

terminated with a resistorof1.2megaohm.
The maximum input voltageis250Vrms.
©ATTx 10Switch
The ATT(enuation)x 10switchisprovidedto
enabletheinternalATTenuatorcircuit
operation.
Ifthisswitchispressed(m),the input
signaltochannelA isattenuated into 1/10and
thenreachesthecounter.
Ifthisswitchispressedagain(ML),the input
signaltochannelA reachesthecounter without
attenuation.
Note that thisswitchcanworktogether with
channelA onlybutdoesnotaffectchannelB.
©- SLOPE Switch
The-SLOPE switchisprovidedto permit the
user toselectpositive-goingedgeornegative-
going edgeofthe CHANNEL A signalfor syn-
chronization.
Ifthisswitchispressed (-••-), negative-going
edge will beselectedforsynchronization.
Ifthisswitchispressedagain (JBL), positive-
going edge will beselectedforsynchronization.
©LPFSwitch
The LPFswitchisusedtoenablethelow pass
filter circuitoperation.
Ifthisswitchispressed(m),the input signal
tochannelA isforcedtoentera low pass
filter ofabout10kHz.
Ifpressedagain (JB_), the input signalreaches
thecounterdirectly. This LPFswitchdoesnot
affectchannelB.
@TRIG.LEVEL ControJ/PUSH PRESET
TheTRIG.LEVEL control/PUSH RESET isa
knobprovidedtoallowtheusertoadjustthe
trigger levelofthe input signalstothe
CHANNEL A input juck.
Iftheknobispressed (-**-), the trigger level
ofanobjectsinewavesignalissettoits
center.
Iftheknobispulled(ML)andthen rotated
counterclockwise,the trigger levelmovestoan
earlier point.
Iftheknobispulled(JH.)andthen rotated
clockwise, the trigger levelmovestoa later
point.
11

© RESET Switch
TheRESET switchisprovidedtoclearthe
counter into 0. This switchcanwork,independ-
entlyofanyoperationmodeselectedby FUNC
switch©.
Ifthisswitchispressedthecounter will
beresetto0.
Ifthisswitchisreleased,a newmeasurement
cycle will bestarted.
©HOLDSwitch
The HOLDswitchisprovidedtoperform
variousoperationsshownbelow. Notethat the
HOLD switchfunctionsdependonoperational
modesselectedby FUNC switch©.
a. • Intheoperationmodesotherthantheevent
total countmeasurementmode (TOTAL/A) :
Ifthisswitchispressed(thecurrent
measurementvalueindicatedbythedisplay
LEDs is'held'andthecounterisreset.
Ifpressedagain (JB-), a newmeasurement
will bestarted.
The displayvaluebeing'held'isnotupdated
until thenewmeasurementiscomplete.
b. Event total counter (TOTAL/A) mode:
Ifthisswitchispressed),thecurrent
measurementvalueindicatedbythedisplay
LEDs is'held'andtheevent total countis
terminated.Ifpressedagain (JHL), a new
countingoperation will bestarted. Notethat
theTTLlevelofthegate input signaltothe
TOTALIZE INPUT/STOP input juck©shouldbe
Highortheterminalshouldbe left 'open'
beforethenewcountingoperationisstarted.
©MHz/ms (jnL)/kHz/j«s (JB.)Switch
(Hereafter,thisswitchisexplainedasthe
'display unit select'switch.)
Ifthisswitchispressed(_••_)inthefrequency
measurementmodeortheself-checkoperation
mode,themeasurementvalue will bedisplayed
inmegaherz,intheperiodor time interval
measurementmode,themeasurementvalue will
bedisplayedinmilliseconds.
Ifthisswitchispressedagain(ML), the meas-
urementdata will bedisplayedinkiloherzor
microseconds.
12

• This switchishelplessinthefrequency ratio
measurementmodeandevent total count meas-
urementmode,
® FUNC Switch/Modedisplay LEDs
The FUNC switchisprovidedtoselectthe
desiredoperationalmode from theavailable
modes.
The modedisplay LEDs areprovidedtoindicate
themeasurementmodeselectedbythisswitch.
The following operationalmodescanbeselected
with thisswitch,
a. FREQ/A (frequency)mode
TheFREQ/A modeisanoperationalmodein
whichthiscountermeasuresthefrequenciesof
input signalstochannelA and outputs them
tothedisplaysection. They aredisplayedin
eitherkHzorMegaHerz(MHz).Thedisplay
unit canbeselected with display unit select
switch@ andindicatedbyeitherdisplay unit
indicatorLED® or(D.Thedisplayresolution
can beselected with GATE switch©.
The measurementfrequencyrangesineach
displayrangeareasfollows:
kHz range:
5Hz to10MHz
Measurementsensitivity:
5Hz to5MHz: 20mVrms
MHzrange:
1MHzto175MHz
Measurementsensitivity:
5MHto125MHz: 50mVrms
125MHzto150MHz: 100mVrms
150MHzto175MHz: 150mVrms
The properrangeshouldbeusedaccordingto
input signalfrequencies with eachrangechar-
acteristics fully inmind,
b. PER/A (Period)mode
ThePER/A modeisanoperationalmodein
whichthis product measurestheperiod
of input signalstochannelA andthen
outputs themtothedisplaysection. They
are displayedinthe unit selectedbydisplay
unit selectswitch@.Thatdisplay unit is
indicatedbyeitherdisplay unit indicatorLED
(3) or@.Thedisplayresolutioncanbe
selected with GATE switch©.
13

c. RATIO A/B(frequencyratio)mode
The RATIO A/Bmodeisanoperationalmode
inwhichthisproduct measures both signals
* onchannelsA andB,andthencomparesthe
CHANNEL B signalswiththoseon CHANNEL
A (A/B)forratiocalculation.
The displayresolutioncanbeselectedwith
GATE switch©.*
d. Tl/A-*B (timeinterval)mode
The Tl/A->B modeisanoperationalmode
inwhichthiscounterproduct measures the
timeintervalbetweena selectededgeofthe
CHANNEL A signalanda selectededgeof
the CHANNEL B signal.
The edgecanbeselectedfrompositive-going
and negative-goingedgesof each signalwith
-SLOPE switches© and@.Themeasurement
data isdisplayedin^sormsselectedby
display unitselectswitch©.Thatdisplay
unitisindicatedbyeithermeasurementunit
display LED© or®.Thedisplayresolution
can beselectedwith GATE switch®.
e. ' TOTAL/A (eventinput total count)mode
The TOTAL/A modeisanoperationalmode
inwhichthisproduct measures thenumberof
channel A input cycles andthenoutputs each
countvaluetothedisplaycontinuously.
This cycle countanddisplayoperationscan
be externallycontrolledwiththegatesignal
inputtothe TOTALIZE START/STOP input
juck ontherearpanelor HOLD switch© on
the front panel.
f. CHECK/10MHz mode
The CHECK/10MHz modeisanoperational
modeinwhichthisuniversalcounter checks
internalfunctions.Ifthisself-checkmodeis
selected, thefrequencyoftheinternaltime
base timer(10MHz)willbedisplayedbythe
8-digit 7-segment LEDs.
© GATE Switch/GATE LED
The GATE switchisprovidedtoselecta
desired displayresolutionvalueforthe meas-
urementmodesstartedby FUNC switch©•
This doesnotapplytotheevent total count
14

(TOTAL/A) mode.
The GATE LEDis also providedtoindicate
theselecteddisplayresolution value.
Measurement
mode
Resolution
kHz Frequency
mode
0.01s
0.1s
1.0s
10s
MHz Frequency
mode
0.02s
0.2s
2.0s
Period/Frequency
Ratio/Time Interval
measurement mode
xl
xlO
X100
X1000
4-2 Rear panel
© TOTALIZE INPUT START/STOP Inputjuck
The TOTALIZE INPUT START/STOP inputjuck
is providedtocontroltheeventinputcount
operationmode.
The eventinputcountoperationisenabledif
theinputsignaltothisterminalbecomesactive
(TTL level: 'H').
The eventinputcountoperationisforcedto
terminateiftheinputsignaltothisterminal
becomes inactive(TTLlevel: 'L').Theevent
inputcountoperationis also disabledifthis
terminalisgroundedtothe chassis ground.
@ EXT.IN. Juck
If OSCILLATOR EXT./INT. switch© issetto
theEXT.(leftposition),thisterminalisusedas
an inputterminalforexternaltime base clocks.
© OSCILLATOR EXT./INT. Switch
The OSCILLATOR EXT./INT. switchisprovided
toselecta functionfortheEXT.INjuck.
In short,eithertheinternaltime base oscillator
oranexternaltime base clockoscillatorcanbe
selected withthisswitch.
15

IfthisswitchissettotheEXT.side,the
universal countercanbeconnected with an
external 10-MHztime base clockgeneratorvia
theEXT.INjuck.
IfthisswitchissettotheINT.side,the
universal countercanbeconnected with the
internaltime base oscillator.
©Powersupplyvoltageselector
The powersupplyvoltageselectorisprovided
toselectthesupplyvoltagethatisappliedto
thecounter.
When youchangethecurrentsupplyvoltage,
refer tosection7-1'Maintenance'.
®Power input connector
The power input connectorisprovidedfor
connectinga powercordtothecounter.
Use the accessory powercord.
® Fuse holder
The fuseholderisprovidedtoenabletheuser
toseta protectionfuseinthecounter.
For the100Vor120V-powerrequirement,use
the0.25A/250Vslow-blowtype fuse.
For the220Vor240V-powerrequirement,use
the0.125A/250Vslow-blowtype fuse.
When youreplacethecurrent fuse, referto
section 7-1'Maintenance'
16

Figure 2. Rear panel
17

4-3 Case surface
® There isanopeningonthe case surface. This
openingisprovidedforfineadjustmentofthe
internal TCXO (standardoscillator).
The openingisnormallycovered with a rubber
cap. Ifthe TCXO needstobefineadjusted,
please contactyourdealer.
Figure 3. Case surface
18

5.OPERATING PROCEDURES
Every time whenyoustartusingthe FC-757 Multi-
Functionaluniversalcounter, look attherearpanel
andverify that thepowersupplyvoltageselector
settingindicatesthelevelofthesupplyvoltageto
beactuallyapplied.
1) Connectthe accessory powercord with thepower
input connector(inlet)oftherearpaneland
inserttheAC plug into thenearby outlet.
2) Press the POWER switch(m).Thecounter will
beturnedon.
3) Whenthecounterisswitchedon with allthe
functionalswitchessettoOFF,theLEDdisplay
indicates'0'.
4) Read carefullyChapter3 PRECAUTION FORUSE
(onpage7)tohandlethisinstrumentcorrectly.
5-1Frequencymeasurement
5-1-1FrequencyMeasurement with ChannelA (5Hz
to175MHz)
(1) Input a targetsignal(tobemeasured)to
CHANNEL A input juck©.
(2) Select the FREQ/A modebyusing FUNC
switch@.
(3) Select themeasurement unit with display unit
select switch@.
Ifthedisplay unit selectswitchispressed
(-JM-), themeasurementvalue will be
displayedinMHz/ms.Inthis case, display
unit LED© will beturnedon.
Iftheswitchispressedagain (JUL), the
measurementvalue will bedisplayedin
kHz/^s. Inthis case, display unit LED(3)
will beturnedon.
Note : Themaximummeasurementfrequency
ineachdisplayrange varies depending
onthemeasurementmodes.Inthe
kHz/^s measurementmode,upto
10MHz-frequencycanbeprocessedwhile
themaximumfrequency that canbe
handledintheMHz/msmodeis175MHz.
The properrangeshouldbeusedaccord-
ingto input signalfrequencies with
each rangecharacteristics fully inmind.
19

(4) Selecta desireddisplayresolutionvalue(gate
time) with GATE switch©.
(5) Thefrequencyofthe input signalcurrently
beingmeasured will be output todisplay©.
GATE LED® blinks during themeasurement.
The measurementvalueonthedisplay will
beupdatedatthemomentwhenonemeasure-
mentintervalisover(whenthe GATE LED
becomesinactive).
Note : Themeasurementmaybedelayedor
displaymaybeunstable.Forthese
unexpectedoperations,refertosection
5-6'DisplayDescription'.
(6) IfHOLDswitch© ispressed during frequency
measurement,thecurrentmeasurementvalue
ontheDisplayisheldasitis.Ifpressed
again, a newmeasurementcycle will bestarted.
However,themeasurementvaluecurrentlybeing
displayed will remainunchanged until thenew
measurementcycleiscomplete.Thatis,the
displayvaluebeingheldbytheHOLDswitch
is updatedbythe output value from thenew
measurementoperation.
(7) If RESET switch© ispressed during frequency
measurement,themeasurementvalueonthe
Display will beresetto'0'.Ifreleased,a
newmeasurementcycle will bestarted.
However,themeasurementvalue will remain
'0' until thenewcycleiscomplete.
Input AdjustmentFunctions
1) Input Adjustment with anLPF
Press LPF(low pass filter)switch© to
eliminatenoisesignalcomponents.Ifthe
internalLPFcircuit function isenabled,the
input signaltothe CHANNEL A juckis
handledfirstbytheLPFcircuit(about
10kHz) andthen input tothecounter.
Therefore, thecounterprocesses input signals
without high-frequencynoisesonly.Asa
result,accuratelow-frequencymeasurement
is assured.
2) ATTx 10switch
Press ATTx 10switch (-ML) accordingto
input signallevels.
Iftheinternalattenuatorcircuitisenabled,
input signaltothe CHANNEL A juckis
20