HP-300A-Brochure 电路图.pdf

HARMONICWAVE Model300A ANALYZER A New Wave Analyzer Featuring VARIABLESELECTIVITY SIMPLIFIEDOPERATION IMPROVEDSTABILITY WIDEVOLTAGERANGE LINEARMETERSCALE USES:The many newfeaturesoftheModel300AHar- monicWaveAnalyzer make it an excellentinstrument forbothlaboratoryandproductionworkwhereaccurate andrapidmeasurementofindividualcomponentsofa complexwaveisrequired. The maximum selectivityissufficientformeasurementof harmonicsoffrequenciesas low as30cycles.Further- more,theselectivitycanbevariedovera widerangeby meansofa.uniqueselectiveamplifierdevelopedinthe Hewlett-Packardlaboratories.Withthisvariableselec- tivityfeature,measurementsathigherfrequenciescanbe madmorerapidly,yetwith nosacrificeinaccuracy. Variableselectivity makes this analyzer usefulformany applicationswhereaconstantselectivity wouldbeun- suitable.For example,variableselectivityisrequiredin measuringdistortionofsoundrecordedon film, disk,or othercaseswheretheremaybea smallamountoffre- quencymodulation.It maybeusedinintegratingthe noisespectrumforacousticmeasurementsorforother purposeswhereawiderpassbandgives amorerepre- sentativeintegration.Inmanyotherwaystheusefulness oftheModel300Aisincreased,becausetheselectivity canbevariedatwill. ThewidevoltagerangeoftheModel300Acoversthe valuesencounteredinnearlyeveryapplication.The meter,whichisfullyprotectedagainstoverloads,is linear,andthevarious scaleshaveampleoverlapfor accuratedreadings.A built-incalibratingsystemispro- videdtostandardizethevoltagemeasurements. Theaccuracy,stability, flexibility,andeaseofoperation ofthis newwaveanalyzer assuretime-savingperform- anceforanyapplicationrequiringafrequency-selective voltmeter. T-I03 RadioFans.CN 收音机爱 好者资料库 DESCRIPTION:The Model 300Aisa frequency-selective voltmeter of the heterodyne type.Itconsistsofa vari- able local oscillator which modulatestheunknown voltage toproduce a constant frequency whichisequaltothe difference between the local oscillator frequency and the unknown frequencythatisbeing measured.Thiscon- stantdifference frequencyispassed through a selective amplifier, theoutputvoltage of whichisthen propor- tionaltothe magnitude of theunknownvoltage. A meter isplacedintheoutputofthe selective amplifierto measure the magnitude of the volj-age. Thelocal oscillatorisoftheresistance-tunedtypewhich provides stability, accuracyofcalibration, and freedom from magnetic fields.A balanced modulatorisusedto eliminate the local oscillator frequency andtoinsurelow cross-modulation products.Theselective amplifier con- sistsoffour tuned circuitsinwhichtheeffectiveQis controlled by feedback.Thisamplifier hastheunique characteristicthattheselectivity may be varied over u wide range without appreciably affectingthegainofth:l amplifier. Onthefront panel arethemain frequency selecting dial, anincremental frequency dial for fine adjustment, vari able selectivity control, meter, range selectors, and inpu: control. Atthe bottom of the main panel arethebalancingallI calibrating controls and a calibratingmeterwhichisused tocheck the sensitivity againsttheline voltage.Thes controls are mountedina small, recessedcompartment which may be closed during normal operation. Theinstrument has been designed throughout for ease o( operation and for accuracy whichwillbemaintained over long periods of time. l FREQUENCYRANGE: VOLTAGE RANGE: SELECTIVITY: VOLTAGEACCURACY: INPUT IMPEDANCE: POWERSUPPLY: MOUNTING: SPECIFICATIONS Thefrequency rangeisfrom 30to16,000 cps. The frequency calibrationiswithin3%. There are four input voltage ranges having maximum values of 0.5 volts, 5 volts, 50 volts, and 500 volts.Inaddition, a meter multiplier divides each voltage range into fullscalemeterreadings of 500, 250,100,50, 25,10,5,2.5, andI.Thusfullscale meter readings can beobtainedonfrom Imvto500v.The meterislinear andisfully protectedagainst overloads. Theselectivity can be variedbymeans of a control on the front panel.Atthemaxi- mumselectivity setting,theresponseisdown 3 db.at3 cycles,10db.at8 cycles, 40 db.at30cycles, and 60db.at50 cycles from maximum response.Thisselectivity call be varied continuously untilattheminimum selectivity the band width required for a given attenuationissixtimesthatatthemaximum selectivity setting.Thus,atmini- mumselectivitytheresponseisdown 3 db.at18cycles,10db.at48 cycles, 40 db. at180cps, and 60 db.at300 cycles from maximum response. The variable selectivity controliscalibratedinthe half band widthatwhich the responseisdown 40 db. Theover-all voltage accuracyis5%,providedadjacentharmonics are within limits determined bytheselectivity.The characteristics of the metering circuit are such thatmeasurement of a particular component may be made with5%accuracy, pro- vided unwanted voltages areattenuatedto less than 1/3 ofthevoltage being meas- ured. Thus, with maximum selectivity a I% second harmonic of a 40 cycle voltage may be measured with5%accuracy. The residual modulation products are suppressed byatleast 65db.Humisatleast 75db. below maximum input voltage on any ofthefour input ranges. The input impedanceis200,000 ohms.The input circuit includes apotentiometer whichissettomaximum for voltage measurements. The instrument contains a voltage regulated power supply whichoperatesfromI10 volts, 60 cycles. TheModel300Aismountedinanattractiveoakcabinetto harmonize with the panel whichisfinishedinwrinkle grey with machine engraved designations.A relay rack modelisalso available andisdesignatedas the Model 300AR. Model 300A 300AR Mounting Cabinet RelayRack Length 21 19 HeightDepth 13 12 Shipping Weight 180# 170# Pricesanddeliveryinformationareavailableonrequest. Thesedataaresubiecttochangewithoutnotice. HEWLETT-PACKARDCOMPANY 481PAGEMILLROAD PALO ALTO,CALIFORNIA December10,19+0 RadioFans.CN 收音机爱 好者资料库