KrohnHite-4402B-osc-sm维修电路原理图.pdf

Model 4402B Ultra-Pure Sinewave Oscillator 1Hz to 110kHz Typical Distortion of 0.0005% Serial No. _ Operating Manual 15 Jonathan Drive, Unit 4, Brockton, MA 02301 U.S.A. Tel: (508) 580-1660; Fax: (508) 583-8989 www.krohn-; infokrohn- Copyright 2006 Krohn-Hite Corporation. All rights reserved. Contents of this publication may not be reproduced in 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 CONTENTS SECTION 1 . . . GENERAL DESCRIPTION . . . . . . . . . . . . 1-1 1.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1-1 1.2 . . . . . SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . 1-1 1.2.1 . . FREQUENCY . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.2.2 . . MAIN OUTPUTS . . . . . . . . . . . . . . . . . . . . . 1-2 1.2.3 . . FIXED OUTPUT . . . . . . . . . . . . . . . . . . . . . 1-2 1.2.4 . . QUADRATURE OUTPUT. . . . . . . . . . . . . . . . 1-3 1.2.5 . . GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1.2.6 . . OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 SECTION 2 . . . OPERATION . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 . . . . . POWER REQUIREMENTS . . . . . . . . . . . . . . . 2-1 2.2 . . . . . OPERATING CONTROLS AND CONNECTORS . 2-2 2.2.1 . . REAR PANEL . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.3 . . . . . OPERATION . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2.3.1 . . FREQUENCY CONTROL . . . . . . . . . . . . . . . . 2-3 2.3.2 . . AMPLITUDE CONTROL . . . . . . . . . . . . . . . . 2-3 2.3.3 . . FLOATING GROUND . . . . . . . . . . . . . . . . . . 2-3 SECTION 3 . . . INCOMING ACCEPTANCE . . . . . . . . . . . . 3-1 3.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 3-1 3.2 . . . . . LIST OF EQUIPMENT REQUIRED . . . . . . . . . 3-1 3.3 . . . . . PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.3.1 . . DC LEVEL ADJUSTMENTS . . . . . . . . . . . . . . 3-2 3.3.2 . . FREQUENCY ACCURACY . . . . . . . . . . . . . . 3-2 3.3.3 . . MAIN OUTPUT AMPLITUDE. . . . . . . . . . . . . 3-2 3.3.4 . . AMPLITUDE FLATNESS. . . . . . . . . . . . . . . . 3-3 3.3.5 . . OUTPUT DISTORTION . . . . . . . . . . . . . . . . . 3-3 SECTION 4 . . . CIRCUIT DESCRIPTION . . . . . . . . . . . . . 4-1 4.1 . . . . . THEORY OF OPERATION . . . . . . . . . . . . . . . 4-1 4.2 . . . . . AVC OPERATION . . . . . . . . . . . . . . . . . . . . 4-2 SECTION 5 . . . MAINTENANCE . . . . . . . . . . . . . . . . . . . 5-1 5.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 5-1 5.2 . . . . . EQUIPMENT REQUIRED . . . . . . . . . . . . . . . 5-1 5.3 . . . . . PRELIMINARY SET-UP . . . . . . . . . . . . . . . . 5-2 5.4 . . . . . PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . 5-2 Table of Contents - i Table of Contents RadioFans.CN 收音机爱 好者资料库 SECTION 6 . . . CALIBRATION . . . . . . . . . . . . . . . . . . . 6-1 6.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 6-1 6.2 . . . . . EQUIPMENT REQUIRED . . . . . . . . . . . . . . . 6-1 6.3 . . . . . TEST PROCEDURE . . . . . . . . . . . . . . . . . . . 6-2 6.3.1 . . POWER SUPPLY CHECK. . . . . . . . . . . . . . . 6-2 6.3.2 . . AVC ADJUSTMENT . . . . . . . . . . . . . . . . . . . 6-2 6.3.3 . . OUTPUT DC LEVEL ADJUSTMENT . . . . . . . . 6-2 6.3.4 . . FREQUENCY CALIBRATION (Bands x1 - x1k) . 6-2 6.3.5 . . FREQUENCY CALIBRATION (x10k Band) . . . . 6-3 6.3.6 . . DISTORTION CHECK. . . . . . . . . . . . . . . . . . 6-3 SECTION 7 . . . PARTS LIST . . . . . . . . . . . . . . . . . . . . . 7-1 7.1 . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 7-1 ii - Table of Contents Model 4402B Ultra-Pure Sinewave Oscillator RadioFans.CN 收音机爱 好者资料库 FIGURES Section 1 Figure 1.1 . Typical Output Distortion . . . . . . . . . . . . . . . 1-3 Section 2 Figure 2.1 . Operating Controls and Connectors . . . . . . . . . 2-1 Section 3 Figure 3.1 . Test Set-Up for Measuring Amplitude Flatness. . 3-2 Figure 3.2 . Amplitude Flatness Test Set-Up . . . . . . . . . . . 3-3 Section 4 Figure 4.1 . Model 4402B Simplified Block Diagram . . . . . . 4-1 Figure 4.2 . Simplified AVC Diagram . . . . . . . . . . . . . . . . 4-2 Section 5 Figure 5.1A. . Troubleshooting Flowchart. . . . . . . . . . . . . 5-3 Figure 5.1B . . Troubleshooting Flowchart. . . . . . . . . . . . . 5-4 Table of Contents - iii Table of Contents RadioFans.CN 收音机爱 好者资料库 iv - Table of Contents Model 4402B Ultra-Pure Sinewave Oscillator Model 4402BSinewave Oscillator RadioFans.CN 收音机爱 好者资料库 SECTION 1 GENERAL DESCRIPTION 1.1INTRODUCTION The 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, audio preamplifier and power amplifier harmonic distortion. With its exceptionally flat response (0.02dB), the 4402B eliminates the need to constantly monitor voltage levels, during frequency response tests. The4402Bprovidesa7Vrmssinewaveoutput,(balancedoutput,14Vrmsend-to-end),3.5Vrmsinto50 ohms, and has no loss in performance when loaded with a linear 50 ohm load. A3-position,push-buttonattenuatorcalibratedin20dBsteps,alongwiththea30dBvernier,providesa total dynamic range of 90dB. Simultaneous fixed and quadrature (90) outputs are provided. Each output is 7Vrms with 600 ohm source impedance. The 4402B is the perfect addition to your present test and/or precision measurement set-up. 1.2SPECIFICATIONS The following specifications apply to the Main, Quadrature and Fixed Outputs, except where noted. 1.2.1 FREQUENCY Range: 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 providing continuous coverage between the 0.1Hzsteps, plus a5decade push-button multiplier withoverlapping ranges. 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 - 1-1 General Description - Section 1 RadioFans.CN 收音机爱 好者资料库 1.2.2 MAIN OUTPUTS MaximumAmplitude:7Vrmsopencircuit(balancedoutput,14Vrmsend-to-end);3.5Vrms;+48dBm into 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 10kHz<0.0005106 10kHz to 20kHz<0.001895 20kHz to 50kHz<0.005685 50kHz 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 Range x11.00Hz to 11Hz x1010.0Hz to 110Hz x100100Hz to 1.1kHz x1k1.00kHz to 11kHz x10k10.0kHz to 110kHz 2.3.2 AMPLITUDE CONTROL TheMainOutputcontroliscontrolledbya4-positionpush-buttonattenuator;andasingleturnvari- ablecontrol.Theattenuatoriscalibratedin20dBstepsfrom0dBto60dB.TheVOLTSRMScontrol is calibrated in volts and provides an additional 30dB coverage on each attenuator position. Attenuator Volts RMS Range (Main Output) 0dB220mV to 7V 20dB22mV to 700mV 40dB2mV to 70mV 60dB220V to 7mV To 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 at 7Vrms. The output impedance of each of these outputs is 600 ohms. 2.3.3 FLOATING GROUND TheCIRCUITGROUNDswitchontherearpanelallowstheoscillatorto“float”orisolatetheoscillator circuit or signal ground from the chassis or earth ground. Maximum allowable DC isolation is 100V. Operation - 2-3 Operation - Section - 2 RadioFans.CN 收音机爱 好者资料库 This page intentionally left blank. 2-4 - Operation Model 4402B Ultra-Pure Sinewave Oscillator RadioFans.CN 收音机爱 好者资料库 SECTION 3 INCOMING ACCEPTANCE 3.1INTRODUCTION The following procedure should be used to verify the oscillator is operating within specifications, both forincominginspectionandroutineservicing.Testsshouldbemadewiththecoverinplace,andthepro- cedure given belowshould befollowedinsequence. Familiarize yourself withthe set-up andoperating procedures outlined in Section 2, Operation. 3.2LIST OF EQUIPMENT REQUIRED 1.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, better than 3% accuracy. 4.RMS Voltmeter for Measuring Amplitude Flatness: Able to measure ac voltage variations of <0.02dB (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 - 3-1 Incoming Acceptance - Section 3 Thecoveroftheunitshouldnotberemovedwhenthein- strumentisconnectedtoanacpowersource,becauseof potentiallydangerousvoltagesthatexistwithintheunit. CAUTION! RadioFans.CN 收音机爱 好者资料库 3.3PROCEDURE Allow the Model 4402B to warm-up for at least 30 minutes, then set the controls on the front and rear panels 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 ADJUSTMENTS Connect the DVM to the Main Output and adjust the rear panel screwdriver control marked “MAIN OUTPUT DC LEVEL” (adjusts the dc level for the top Main Output BNC connector) for a reading of 0V. Repeat the same for the bottom Main Output marked on the rear panel “MAIN OUTPUT DC LEVEL”. 3.3.2 FREQUENCY ACCURACY Connect the frequency counter to either Main Output. Verify that the frequency accuracy is within 0.05% of the FREQUENCY Hz setting between 1Hz and 110kHz. 3.3.3 MAIN OUTPUT AMPLITUDE Setthe4402Bfrequencyto1kHz(1-0-0X1k).ConnecttheACVMtotheMainOutput;withtheVOLTS RMScontrolsettomaximumCW,theMainOutputshouldbe?7Vrms.RotatetheVOLTSRMScontrol to minimum (counter clockwise, CCW), the Main Output should be <220mV. Turn the VOLTS RMS clockwisetoobtainareadingof7Vrms.Connecta50ohmresistor 1%acrossthetopBNCoftheMain Output; 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 the QUAD OUTPUT. 3-2 - Incoming Acceptance Model 4402B Ultra-Pure Sinewave Oscillator Figure 3.1 Test Set-Up for Measuring Amplitude Flatness RadioFans.CN 收音机爱 好者资料库 3.3.4 AMPLITUDE FLATNESS (see set-up on next page) AmplitudeflatnessisdefinedasthemaximumdeviationfromconstantamplitudeexpressedindBor% over a specified frequency range. Since few ac voltmeters are capable of accurately measuring voltage deviations <0.02dB (0.23%) up to 100kHz, the use of a high frequency thermal converter, and either a differentialdcvoltmeterordcnullmeterwithacalibratedorstabledcsupply,isrecommended(seeFig- ure 3.1). Minimize the capacitance in the meter leads to avoid loading effects at the higher frequencies. SetthefrequencyoftheModel4402Btoareferencefrequencyof1kHzandadjustthevoltmeterornull meter for a 0dB/0% deviation. Tune the oscillator frequency from 10Hz to 110kHz. The Main Output should 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 DISTORTION The use of a spectrum or wave analyzer (HP, BandthetwoCvalues by the frequency MULTIPLIER switch S103. TheMainOutputisprovidedbyU183,whichisfedfromtheVOLTSRMScontrolpotentiometer,R180. The FIXED Output is derived from the oscillator loop. The signal on the common point of the bridge T capacitors is lagging the oscillator loop signal by 90. This signal is buffered by amplifier U103 and fed to the frequency vernier, R104, the band calibration potentiometers (R110 through R113 and R122), and the QUAD Output amplifier U100. 4.2AVC OPERATION The AVC system is shown in Figure 4.2. Theoscillator loop output signal in Figure 4.1is fedto the peak detector diode CR163and inverter am- plifierU138,whichinvertsthesignalanddrivesCR162forpeakdetectiononboth+andpeaks.Italso feedsoneinputofthelinearmultiplierU145.Themultiplierfunctionsasavariablegainintheregenera- tive path of the oscillator. 4-2 - Circuit Description Model 4402B Ultra-Pure Sinewave Oscillator Figure 4.2 Simplified AVC Diagram RadioFans.CN 收音机爱 好者资料库 The peak detector charges its capacitor to the plus peak value of the sinewave and is fed to one input of U165A,theDetectorBuffer.Adifferenceorerrorvoltageproportionaltothedifferencebetweentheref- erence and detected value is produced onthe output ofU165A.Theerror voltage is fedto the AVCam- plifier,U150B,foradditionalfilteringanddcgain.TheAVCamplifieroutputfeedsU150whichinturn drives the second input of the linear multiplier U145. This control loop varies the regenerative gain thereby controlling the oscillator loop amplitude. AsmallportionoftheerrorsignalontheoutputofU165AisfeddirectlytotheinputofU150B,bypass- ing the AVC amplifiers time delay and stabilizing the control loop from oscillating. Tominimizeamplitudetransients whenchangingfrequency,andtospeeduptherecovery oftheampli- tude control loop, certain circuit refinements are added. Onthe lower twobands (x1and x10) the peak detector the peak detector capacitor is electrically multi- pliedupinvaluebyamplifierU165B.TheOutputofU165Bisdynamicallylimitedsothatonlargeam- plitude changes, U165B no longer multiplies the capacitor values, and the peak detector can respond more quickly. TofurtherenhancetheAVCresponsetoalargeamplitudetransient,additionalfeedforwardtoU150Bis provided by back-to-back diodes from the peak detector buffer. TooptimizetheAVCamplifierstimeconstant,theinputresistorfeedingU150Aisswitchedwiththefre- quency MULTIPLIER. Circuit Description - 4-3 Circuit Description - Section 4 RadioFans.CN 收音机爱 好者资料库 This page intentio