KrohnHite-4402B-osc-sm 维修电路原理图.pdf

Model 4402BUltra-Pure Sinewave Oscillator1Hz to 110kHzTypical Distortion of 0.0005%Serial No. _Operating Manual15 Jonathan Drive, Unit 4, Brockton, MA 02301 U.S.A.Tel: (508) 580-1660; Fax: (508) 583-8989www.krohn-; infokrohn-Copyright 2006 Krohn-Hite Corporation. All rights reserved. Contents of this publication may not be reproducedin any form without the written permission of Krohn-Hite Corporation. Printed in USA - 7/06.RadioFans.CN 收音机爱 好者资料库RadioFans.CN 收音机爱 好者资料库TABLE OF CONTENTSSECTION 1 . . . GENERAL DESCRIPTION . . . . . . . . . . . . 1-11.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1-11.2 . . . . . SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . 1-11.2.1 . . FREQUENCY . . . . . . . . . . . . . . . . . . . . . . . 1-11.2.2 . . MAIN OUTPUTS . . . . . . . . . . . . . . . . . . . . . 1-21.2.3 . . FIXED OUTPUT . . . . . . . . . . . . . . . . . . . . . 1-21.2.4 . . QUADRATURE OUTPUT. . . . . . . . . . . . . . . . 1-31.2.5 . . GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . 1-31.2.6 . . OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3SECTION 2 . . . OPERATION . . . . . . . . . . . . . . . . . . . . . 2-12.1 . . . . . POWER REQUIREMENTS . . . . . . . . . . . . . . . 2-12.2 . . . . . OPERATING CONTROLS AND CONNECTORS . 2-22.2.1 . . REAR PANEL . . . . . . . . . . . . . . . . . . . . . . . 2-22.3 . . . . . OPERATION . . . . . . . . . . . . . . . . . . . . . . . . 2-32.3.1 . . FREQUENCY CONTROL . . . . . . . . . . . . . . . . 2-32.3.2 . . AMPLITUDE CONTROL . . . . . . . . . . . . . . . . 2-32.3.3 . . FLOATING GROUND . . . . . . . . . . . . . . . . . . 2-3SECTION 3 . . . INCOMING ACCEPTANCE . . . . . . . . . . . . 3-13.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 3-13.2 . . . . . LIST OF EQUIPMENT REQUIRED . . . . . . . . . 3-13.3 . . . . . PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . 3-23.3.1 . . DC LEVEL ADJUSTMENTS . . . . . . . . . . . . . . 3-23.3.2 . . FREQUENCY ACCURACY . . . . . . . . . . . . . . 3-23.3.3 . . MAIN OUTPUT AMPLITUDE. . . . . . . . . . . . . 3-23.3.4 . . AMPLITUDE FLATNESS. . . . . . . . . . . . . . . . 3-33.3.5 . . OUTPUT DISTORTION . . . . . . . . . . . . . . . . . 3-3SECTION 4 . . . CIRCUIT DESCRIPTION . . . . . . . . . . . . . 4-14.1 . . . . . THEORY OF OPERATION . . . . . . . . . . . . . . . 4-14.2 . . . . . AVC OPERATION . . . . . . . . . . . . . . . . . . . . 4-2SECTION 5 . . . MAINTENANCE . . . . . . . . . . . . . . . . . . . 5-15.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 5-15.2 . . . . . EQUIPMENT REQUIRED . . . . . . . . . . . . . . . 5-15.3 . . . . . PRELIMINARY SET-UP . . . . . . . . . . . . . . . . 5-25.4 . . . . . PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . 5-2Table of Contents - iTable of ContentsSECTION 6 . . . CALIBRATION . . . . . . . . . . . . . . . . . . . 6-16.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 6-16.2 . . . . . EQUIPMENT REQUIRED . . . . . . . . . . . . . . . 6-16.3 . . . . . TEST PROCEDURE . . . . . . . . . . . . . . . . . . . 6-26.3.1 . . POWER SUPPLY CHECK. . . . . . . . . . . . . . . 6-26.3.2 . . AVC ADJUSTMENT . . . . . . . . . . . . . . . . . . . 6-26.3.3 . . OUTPUT DC LEVEL ADJUSTMENT . . . . . . . . 6-26.3.4 . . FREQUENCY CALIBRATION (Bands x1 - x1k) . 6-26.3.5 . . FREQUENCY CALIBRATION (x10k Band) . . . . 6-36.3.6 . . DISTORTION CHECK. . . . . . . . . . . . . . . . . . 6-3SECTION 7 . . . PARTS LIST . . . . . . . . . . . . . . . . . . . . . 7-17.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 7-1ii - Table of ContentsModel 4402B Ultra-Pure Sinewave OscillatorFIGURESSection 1Figure 1.1 . Typical Output Distortion . . . . . . . . . . . . . . . 1-3Section 2Figure 2.1 . Operating Controls and Connectors . . . . . . . . . 2-1Section 3Figure 3.1 . Test Set-Up for Measuring Amplitude Flatness. . 3-2Figure 3.2 . Amplitude Flatness Test Set-Up . . . . . . . . . . . 3-3Section 4Figure 4.1 . Model 4402B Simplified Block Diagram . . . . . . 4-1Figure 4.2 . Simplified AVC Diagram . . . . . . . . . . . . . . . . 4-2Section 5Figure 5.1A. . Troubleshooting Flowchart. . . . . . . . . . . . . 5-3Figure 5.1B . . Troubleshooting Flowchart. . . . . . . . . . . . . 5-4Table of Contents - iiiTable of Contentsiv - Table of ContentsModel 4402B Ultra-Pure Sinewave OscillatorModel 4402BSinewave OscillatorSECTION 1GENERAL DESCRIPTION1.1INTRODUCTIONThe Model 4402B is an ultra-pure sinewave, stable amplitude oscillator designed to meet the needs of to-days high precision 16 to 18 bit A/D converter testing, and audio test and measurement technology.Covering the frequency range from 1Hz to 110kHz, with precise 3 digit frequency tuning, the 4402B pro-duces a virtually “distortion-free” (0.0005%) sinewave for measuring A/D converter accuracy, audiopreamplifier and power amplifier harmonic distortion. With its exceptionally flat response (0.02dB), the4402B eliminates the need to constantly monitor voltage levels, during frequency response tests.The4402Bprovidesa7Vrmssinewaveoutput,(balancedoutput,14Vrmsend-to-end),3.5Vrmsinto50ohms, and has no loss in performance when loaded with a linear 50 ohm load.A3-position,push-buttonattenuatorcalibratedin20dBsteps,alongwiththea30dBvernier,providesatotal dynamic range of 90dB.Simultaneous fixed and quadrature (90) outputs are provided. Each output is 7Vrms with 600 ohmsource impedance.The 4402B is the perfect addition to your present test and/or precision measurement set-up.1.2SPECIFICATIONSThe following specifications apply to the Main, Quadrature and Fixed Outputs, except where noted.1.2.1 FREQUENCYRange: 1Hz to 110kHz.Accuracy: 0.5% of frequency setting.Control: 2 digits of frequency, calibrated in 1Hz and 0.1Hz steps, with a calibrated vernier providingcontinuous coverage between the 0.1Hzsteps, plus a5decade push-button multiplier withoverlappingranges.Stability:Vs. Time: 0.01% in 1 hour or less.Vs. Temperature: 0.05%/C.Vs. Line: 0.001% for a 10% change in line voltage.General Description - 1-1General Description - Section 11.2.2 MAIN OUTPUTSMaximumAmplitude:7Vrmsopencircuit(balancedoutput,14Vrmsend-to-end);3.5Vrms;+48dBminto 50 ohm load (balanced output, 7V rms end-to-end).Impedance: Constant 50 ohms.Maximum Current: 75mArms.Minimum Amplitude: 0.2mV.Amplitude Flatness: 0.02dB, 1Hz to 110kHz.Amplitude Stability:Vs. Time: 0.01% in 1 hour or less.Vs. Temperature: 0.05%/C.Vs. Line: 0.001% for a 10% change in line voltage.Amplitude Control: A4-position push-button attenuator calibrated in20dBsteps from0dBto60dB,Accuracy,0.25dB/20dBstep;Voltsrmscontrolwithgreaterthan30dBofcoveragecalibratedinvolts.Accuracy: 20% of setting.Main Output Distortion:FrequencyDistortion %Distortion (dB)1Hz to 10kHz0.000510610kHz to 20kHz0.00189520kHz to 50kHz0.00568550kHz to 110kHz9, and provides additional resolution between the 0.1Hz steps.The 5-band push-button multiplier is calibrated in decade steps from x1 to x10k.MultiplierFrequency Rangex11.00Hz to 11Hzx1010.0Hz to 110Hzx100100Hz to 1.1kHzx1k1.00kHz to 11kHzx10k10.0kHz to 110kHz2.3.2 AMPLITUDE CONTROLTheMainOutputcontroliscontrolledbya4-positionpush-buttonattenuator;andasingleturnvari-ablecontrol.Theattenuatoriscalibratedin20dBstepsfrom0dBto60dB.TheVOLTSRMScontrolis calibrated in volts and provides an additional 30dB coverage on each attenuator position.AttenuatorVolts RMS Range(Main Output)0dB220mV to 7V20dB22mV to 700mV40dB2mV to 70mV60dB220V to 7mVTo optimize the resolution of the adjustment, use the lower of the two attenuator settings (e.g. if the ap-plication requires a 500mV rms signal, use the 20dB setting rather than the 0dB setting).The Quad (90) and Fixed (180 out of phase from top Main Output BNC) outputs are fixed at7Vrms. The output impedance of each of these outputs is 600 ohms.2.3.3 FLOATING GROUNDTheCIRCUITGROUNDswitchontherearpanelallowstheoscillatorto“float”orisolatetheoscillatorcircuit or signal ground from the chassis or earth ground. Maximum allowable DC isolation is 100V.Operation - 2-3Operation - Section - 2This page intentionally left blank.2-4 - OperationModel 4402B Ultra-Pure Sinewave OscillatorSECTION 3INCOMING ACCEPTANCE3.1INTRODUCTIONThe following procedure should be used to verify the oscillator is operating within specifications, bothforincominginspectionandroutineservicing.Testsshouldbemadewiththecoverinplace,andthepro-cedure given belowshould befollowedinsequence. Familiarize yourself withthe set-up andoperatingprocedures outlined in Section 2, Operation.3.2LIST OF EQUIPMENT REQUIRED1.Oscilloscope: bandwidth of at least 1MHz, vertical sensitivity 10mV/cm, ac/dc coupled.2.DC Voltmeter: 0V to 15V.3.AC Voltmeter: Frequency range 110kHz, to measure between 0V and 7Vrms, betterthan 3% accuracy.4.RMS Voltmeter for Measuring Amplitude Flatness: Able to measure ac voltage variations of0.02dB (0.23%) from 10Hz to 110kHz.orHigh Frequency Thermal Converter: Fluke Model A55 and either a DC Differential Voltmeter(FlukeModel895A),oraDCNullDetector(FlukeModel845A)withastable,DCreferencesup-ply.5.Spectrum Analyzer: Able to measure harmonic components below 0.0005% (106dB).6.Frequency/Period Counter: Accuracy better than 0.5%, 1Hz to 110kHz.Incoming Acceptance - 3-1Incoming Acceptance - Section 3Thecoveroftheunitshouldnotberemovedwhenthein-strumentisconnectedtoanacpowersource,becauseofpotentiallydangerousvoltagesthatexistwithintheunit.CAUTION!3.3PROCEDUREAllow the Model 4402B to warm-up for at least 30 minutes, then set the controls on the front and rearpanels to the following positions:Frequency Hz: 1kHz (1-0-0 x1k).Amplitude: 0dB, Volts RMS set for maximum clockwise (CW).Circuit Ground: Chassis.3.3.1 DC LEVEL ADJUSTMENTSConnect the DVM to the Main Output and adjust the rear panel screwdriver control marked “MAINOUTPUT DC LEVEL” (adjusts the dc level for the top Main Output BNC connector) for a reading of0V. Repeat the same for the bottom Main Output marked on the rear panel “MAIN OUTPUT DCLEVEL”.3.3.2 FREQUENCY ACCURACYConnect the frequency counter to either Main Output. Verify that the frequency accuracy is within0.05% of the FREQUENCY Hz setting between 1Hz and 110kHz.3.3.3 MAIN OUTPUT AMPLITUDESetthe4402Bfrequencyto1kHz(1-0-0X1k).ConnecttheACVMtotheMainOutput;withtheVOLTSRMScontrolsettomaximumCW,theMainOutputshouldbe?7Vrms.RotatetheVOLTSRMScontrolto minimum (counter clockwise, CCW), the Main Output should be 220mV. Turn the VOLTS RMSclockwisetoobtainareadingof7Vrms.Connecta50ohmresistor 1%acrossthetopBNCoftheMainOutput; the voltage should drop to 3.5Vrms. Repeat the same for the bottom BNC at the Main Output.Remove the 50?terminator.Tochecktheattenuatoraccuracy,adjusttheVOLTSRMScontrolforanACVMreadingof7Vrms.Ver-ify that the attenuation accuracy is within 0.25dB (2.9%) per 20dB step.ConnecttheACVMtotheFIXEDOUTPUT.TheACVMshouldread?7Vrms.Connecta600ohmload(1%) across the FIXED OUTPUT; the amplitude should drop the value. Repeat the same for theQUAD OUTPUT.3-2 - Incoming AcceptanceModel 4402B Ultra-Pure Sinewave OscillatorFigure 3.1 Test Set-Up for Measuring Amplitude Flatness3.3.4 AMPLITUDE FLATNESS (see set-up on next page)AmplitudeflatnessisdefinedasthemaximumdeviationfromconstantamplitudeexpressedindBor%over a specified frequency range. Since few ac voltmeters are capable of accurately measuring voltagedeviations 0.02dB (0.23%) up to 100kHz, the use of a high frequency thermal converter, and either adifferentialdcvoltmeterordcnullmeterwithacalibratedorstabledcsupply,isrecommended(seeFig-ure 3.1).Minimize the capacitance in the meter leads to avoid loading effects at the higher frequencies.SetthefrequencyoftheModel4402Btoareferencefrequencyof1kHzandadjustthevoltmeterornullmeter for a 0dB/0% deviation. Tune the oscillator frequency from 10Hz to 110kHz. The Main Outputshould remain constant within 0.02dB (0.23%) over the entire frequency range.Repeat this procedure for both Main Outputs and the Fixed Output. Repeat for the Quad Output, toler-ance, 2dB (2.5%).3.3.5 OUTPUT DISTORTIONThe use of a spectrum or wave analyzer (HP, B&K, Marconi, etc.) and a pre-filter is recommended fordistortion measurements below 0.001%. The pre-filter consists of a passive “twin-tee” or notch filter,andisusedtoattenuatethefundamentalfrequencyinordertoincreasethesensitivityofthespectrumorwave analyzer.Component Values:R = 7.96k, 1%Center Frequency (Hz)1001k10kCapacitance (F)*0.10.010.001* Capacitance values are 1% toleranceIncoming Acceptance - 3-3Incoming Acceptance - Section 3Figure 3.2 Amplitude Flatness Test Set-UpThe diagram below shows the test set-up for measuring the output distortion of the 4402B.To measure distortion, proceed as follows:1.Set the controls on the analyzer to the following initial positions:ADAPTIVE SWEEPOffDISPLAYClear WriteFREQUENCY1kHzAMPLITUDE MODELog dB/DivAMPLITUDE REFERENCE LEVEL0 (Zero)INPUT SENSITIVITY+20dB (10V)RESOLUTION BANDWIDTH100HzFREQUENCY SPAN/DIV0.5HzSWEEP TIME/DIV1SecSWEEP MODERepetitive2.Set switch S1 to the “INPUT” position. Adjust the 4402B frequency to correspond to the“twin-tee” null frequency.3.Adjust the INPUT SENSITIVITYvernier on the analyzer to obtain a 0dB reference at the funda-mental frequency.4.Switch S1 to the “OUTPUT”position. Adjust the frequency of the 4402B to null the fundamentalfrequency.Itmaybenecessarytomakefineadjustmentstothe“twin-tee”componentvaluestoob-tain sufficient null of the fundamental.5.Increase the INPUT SENSITIVITY in dB steps until the harmonic components are visible.ThedBlevelofeachharmoniccomponentisthesumofthedBbelowthe0dBreferencelevelonthedis-play, plus the change in the INPUT SENSITIVITY level, in dB.To compensate for loss through the “twin-tee” filter, add +9dB to the second harmonic component and+5dB to the 3rd harmonic component.For example, if the second harmonic is 128dB: 128dB +9dB = 119dB.The total harmonic distortion may then be calculated as follows:T H D dBndrdnth. .()logloglog.log?2012101310110Since: log ( )log( )( )?1110 xxxT H D dBdBnddBrddBth. .()log(.?101010102103104101010dBnth)T H D dBdBn. .()log()?101010dBn = sum of all harmonics3-4 - Incoming AcceptanceModel 4402B Ultra-Pure Sinewave OscillatorExample: 2nd harmonic = -40dB3rd harmonic = -46dB4th harmonic = -50dBT H D. .log()log(?10101010101014010461050104010101002510101351034 65? ?.)log(_)log().?873871010011638 720? ?.%()%.dBIncoming Acceptance - 3-5Incoming Acceptance - Section 3This page intentionally left blank.3-6 - Incoming AcceptanceModel 4402B Ultra-Pure Sinewave OscillatorSECTION 4CIRCUIT DESCRIPTION4.1THEORY OF OPERATIONAsimplified block diagram of the oscillating loop is shown in Figure 4.1.The 4402B oscillator is a true RC oscillator designed to generate ultra-pure sinewaves and flat ampli-tude response.Itconsistsoftwofeedbackloopsystems,onetoproducethesinewavesandonetomaintainstableampli-tude.ItusestworesistorsandtwocapacitorsconnectedinabridgeTasthetuningortheresonatingpartofthecircuit.Circuit Description - 4-1Circuit Description - Section 4Figure 4.1 Model 4402B Simplified Block Diagram