KROHNHITE 6900B Operation & Maintenance 电路图.pdf

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1、 5Hz to 1MHz WIDE RANGE FULLY AUTOMATIC DISTORTION ANALYZER MODEL 6900B SERIAL NO. _ OPERATING AND MAINTENANCE MANUAL Unit 4, 15 Jonathan Drive, Brockton, MA 02301-5566 Tel: (508) 580-1660; Fax: (508) 583-8989 E-mail: infokrohn-; Web: www.krohn- RadioFans.CN 收音机爱 好者资料库 Model 6900B Table of Contents

2、TABLE OF CONTENTS 1.0 GENERAL DESCRIPTION. 1-1 1.1 Introduction . 1-1 1.2 Specifications . 1-1 1.3 General Specification. 1-3 2.0 OPERATION. 2-1 2.1 Introductions. 2-1 2.2 Power Requirements. 2-1 2.3 Turn-on Procedure. 2-1 2.4 Controls, Terminals, Indicators. 2-1 2.5 Operation . 2-2 2.6 Optional Fea

3、tures . 2-4 3.0 INCOMING ACCEPTANCE. 3-1 3.1 Introduction . 3-1 3.2 Procedure. 3-1 4.0 CIRCUIT DESCRIPTION. 4-1 4.1 Introduction . 4-1 4.2 Circuit Description. 4-1 5.0 CALIBRATION. 5-1 5.1 Introduction . 5-1 5.2 Calibration Procedure. 5-1 5.3 Power Supply . 5-1 5.4 Voltmeter Calibration. 5-2 5.5 Inp

4、ut Amplifier Calibration. 5-3 5.6 Stepping Amplifier Calibration. 5-3 5.7 Output Amplifier Calibration. 5-3 5.8 Frequency Detector Calibration. 5-4 5.9 1kHz Oscillator Calibration. 5-4 5.10 1kHz Calibration . 5-4 5.11 Integrator Level Calibration. 5-4 5.12 Calibration Adjustments. 5-4 6.0 MAINTENANC

5、E . 6-1 6.1 Introduction . 6-1 6.2 Trouble-Shooting Procedure. 6-1 6.3 Step-by-Step Troubleshooting procedure. 6-1 6.4 Power Supply . 6-6 6.5 ALC Amplifier . 6-6 6.6 Null Amplifier . 6-7 6.7 Meter Amplifier . 6-7 6.8 Operational Rectifier . 6-7 6.9 Integrator. 6-8 6.10 Voltage Discriminator . 6-8 6.

6、11 Frequency Discriminator. 6-8 6.12 Oscillator. 6-8 7.0 PARTS LISTS, SCHEMATICS AND BOARD LAYOUTS . 7-1 7.1 Ordering Information . 7-1 7.2 Ordering Unlisted Parts . 7-1 RadioFans.CN 收音机爱 好者资料库 Model 6900B Figure 1.1 Model 6900B RadioFans.CN 收音机爱 好者资料库 Model 6900B Section 1 General Description SECTI

7、ON 1 GENERAL DESCRIPTION 1.1 INTRODUCTION The Krohn-Hite Model 6900B, illustrated in Figure 1.1, is a Fully Automatic Distortion Analyzer designed or ultra-low distortion and ac voltage measurements in the 5Hz to 1MHz frequency range. The Distortion Analyzer will measure total harmonic distortion (T

8、HD) down to 0.005%, typically, with 0.001% resolution. A unique Auto Set Level feature eliminates the need to manually preset the input reference level before each measurement for any input voltage between 0.1-130 volts rms. An Auto-Null Network provides Auto Nulling of the fundamental frequency ove

9、r the entire frequency range. The Analyzer also measures ac voltages from 10mV to 130 volts rms over the range of 5Hz to 1MHz. The Auto-Ranging Digital Display Meter (DDM) reads directly in percent distortion or ac volts, and eliminates the ambiguities commonly found in analog voltmeter. A 1kHz ultr

10、a-low distortion (0.003%) sinewave output is provided for use as a stimulus to test circuit or system distortion characteristics, or for self-checking of the Analyzer. A switch selectable High-Pass filter reduces the effects of hum and low frequency noise. The 400Hz, 30kHz and 80kHz selectable filte

11、rs are effective only in the DISTORTION MODE. An internal low-pass tracking filter eliminates high frequency noise when making low distortion measurements. A DISTORTION OUTPUT is also provided for visual inspection or spectral analysis of the input signal after the fundamental has been filtered out.

12、 An optional BCD output is available. 1.2 SPECIFICATIONS 1.2.1 DISTORTION METER SPECIFICATIONS 1.2.1.1 FUNDAMENTAL FREQUENCY RANGE: 5Hz to 1MHz automatically tuned over the entire specified input frequency range. An intermittent display indicates an out-of-range condition. 1.2.1.2 INPUT: No presetti

13、ng required over input level from 100mV to 130 volts rms. Impedance; 110k ohms shunted by 100pF. 1.2.1.3 DISTORTION RANGE: A digital panel meter with Auto-Ranging displays percentage of total harmonic distortion (THD) to 19.9%. Measurement (%) Resolution (%) 0.000 - .100 0.001 0.10 - 2.00 0.01 2.0 -

14、 19.9 0.1 1.2.2 DISTORTION MEASUREMENT ACCURACY 1.2.2.1 Input volts: 0.1 0.25 1.2.2.2 Distortion levels: 0.01% 10Hz to 50kHz: 15% of reading or 0.01%, whichever is greater. 5Hz to 100kHz: 15% of reading or 0.02%, whichever is greater. 100kHz to 500kHz: 15% of reading or 0.1%, whichever is greater. 5

15、00kHz to 1MHz: 25% of reading or 0.5%, whichever is greater. 1-1 Section 1 General Description Model 6900B 1.2.2.3 Input volts: 0.25 130 1.2.2.4 Distortion levels: 0.005% 10Hz to 50kHz: 15% of reading or 0.005%, whichever is greater. 5Hz to 100kHz: 15% of reading or 0.01%, whichever is greater. 100k

16、Hz to 500kHz: 15% of reading or 0.05%, whichever is greater. 500kHz to 1MHz: 25% of reading or 0.5%, whichever is greater. 1.2.3 RESIDUAL DISTORTION AND NOISE 1.2.3.1 Input: 0.1V 0.25V 5Hz to 1MHz; less than 0.03% from 5Hz to 50kHz rising to 0.5% at 1MHz. 1.2.3.2 Input: 0.25V 130V 50Hz to 20kHz; les

17、s than 0.01% 5Hz to 1MHz; less than 0.02% from 5Hz to 50kHz rising to 0.5% at 1MHz. 1.2.4 SETTLING TIME (to 0.1% THD): Typically less than 3 seconds from 50Hz to 1mHz. Longer at lower frequencies. 1.2.5 FUNDAMENTAL REJECTION: Greater than 10dB below residual THD. 1.2.6 FILTERS 400Hz High Pass: - 3dB

18、 at 400Hz 10%; 40db/decade rolloff. 30kHz Low Pass: -3dB at 30kHz 5%; 60db/decade rolloff. 80kHz Low Pass: - 3dB at 80kHz 5%; 60db/decade rolloff. 1.2.7 DISTORTION OUTPUT (Residual signal after fundamental is nulled): Voltage; 100mVrms/%THD. Impedance; less than 500 ohms. 1.2.8 ANALOG OUTPUT: 100mVd

19、c/%THD. Impedance; less than 1k ohms. 1.2.9 DIGITAL DISPLAY METER (DDM): Three digit meter with Auto-Ranging. 1.2.10 AC VOLTMETER SPECIFICATIONS 1.2.10.1 Frequency Range: 5Hz to 1MHz. 1.2.10.2 Voltage Range: 0.01V to 130 volts rms. Voltage Range Resolution (volts) 0.01 1 0.001 1 10 0.01 10 130 0.1 1

20、.2.10.3 Accuracy: 2% 1 digit from 10Hz to 500kHz, 5% 1 digit from 5Hz to 1MHz over specified voltage range. 1.2.11 DIGITAL DISPLAY METER: Three digit meter with Auto-Ranging. 1.2.12 INPUT IMPEDANCE: 110k ohms shunted by 100pf. 1-2 Model 6900B Section 1 General Description 1.2.13 OSCILLATOR OUTPUT 1.

21、2.13.1 Frequency: 1kHz, fixed. 1.2.13.2 Output (rms): 5 volts at 3 milliamperes maximum. 1.2.13.3 Distortion: 0.003%. 1.2.13.4 Impedance: 600 ohms. 1.3 GENERAL SPECIFICATIONS 1.3.1 FRONT PANEL CONTROLS MODE switch for selecting either voltmeter (VOLTS) or distortion (% DIST) operation. FILTER switch

22、 for selecting 400Hz High Pass, 30kHz and 80kHz Low Pass operation. POWER switch. 1.3.2 REAR PANELS Switches for selecting 120V/240V ac operation and normal or low (NORM/LOW) as line voltage. 1.3.3 CONNECTORS (BNC) Front panel: INPUT, 1kHz OUTPUT and DISTORTION OUTPUT Rear panel: INPUT, ANALOG OUTPU

23、T 1.3.4 MAXIMUM DC COMPONENT: 100V. 1.3.5 ISOLATION TO CHASSIS: 500Vdc. 1.3.6 OPERATING TEMPERATURE RANGE: 0C to 45C. Unless otherwise noted, specifications apply at 25C 5C. 1.3.7 POWER REQUIREMENTS: Switch selectable, 90-110, 10-8-132, 180-220 or 216-264 volts, single phase, 50-400Hz, 15 watts. 1.3

24、.8 DIMENSIONS AND WEIGHTS: 16.625”/42.3cm wide, 3.5”/9cm high, 14.375”/37.5cm deep, 13.5lb/6.1kg. An optional rack-mounting kit, Part No. RK-319, is available for installing the unit in a standard 19” rack. 1.3.9 BCD OUTPUT (optional): Provides 13 lines of parallel BCD output, plus 1 MODE output, 3

25、decimal point outputs and 4 separate 3-state control lines. Compatible with DTL, RTL and TTL logic. 1-3 Section 1 General Description Model 6900B Figure 1.2 Operating Controls, Connectors and Display 1-4 Model 6900B Section 2 Operation SECTION 2 OPERATION 2.1 INTRODUCTION This section describes the

26、basic operation of the Model 6900B. It includes the proper ac power requirements, the recommended turn-on procedure and a detailed explanation of all operating controls, modes of operation and special optional features. 2.2 POWER REQUIREMENTS The Model 6900B is designed to operate from a single phas

27、e, 50-400Hz ac power source of 90-110, 108- 132, 180-220, or 216-264 volts. Line switches allow the 6900B to be powered from one of the above 4 voltage ranges. The ac power receptacle is a standard 3-pin connector, and complies with the European I.E.C. standard. A detachable 3-wire line cord is prov

28、ided with the instrument. A 2/10A slow blow fuse should be inserted in the fuse receptacle. 2.3 TURN-ON PROCEDURE 2.3.1 Set the line switches for the correct voltage range. For 90-110 volts, set the voltage range to 120V and the NORM/LOW switch to Low. For 108-132 volts, set the voltage range to 120

29、V and the NORM/LOW switch to Normal. For 180-220 volts, set the voltage range to 240V and the NORM/LOW switch to Low. For 216-264 volts, set the voltage range to 240V and the NORM/LOW switch to Normal. 2.3.2 Make sure the POWER switch is in the off position. 2.3.3 Plug the line cord into the unit an

30、d into an ac outlet. WARNING! The chassis of this instrument is connected to ground. For safety purposes, connect the line cord to a grounded, 3 terminal ac outlet. 2.3.4 Turn the POWER switch on, and allow the unit to warm up for several minutes. CAUTION! Because of the potentially dangerous voltag

31、es that exist within the unit, the cover of this instrument should not be removed when the instrument is connected to an ac power source. 2.4 CONTROLS, TERMINAL, INDICATORS 2.4.1 FRONT PANEL: 2.4.1.1 INPUT: Input voltage; 100mV to 130 volts rms in PERCENT DISTORTION MODE, 10mV-130V rms in VOLT MODE.

32、 Input impedance; 110k ohms shunted by 100pf. Maximum dc; 100V. Isolation to chassis; 500Vdc. 2.4.1.2 INPUT LEVEL: LOW LED indicates when the input, in the DISTORTION MODE, is below the minimum level of 100m Vrms. 2.1 Section 2 Operation Model 6900B 2.4.1.3 DIGITAL DISPLAY METER (DDM): Displays dire

33、ctly in percent distortion or ac volts. 2.4.1.4 MODE: Pushbutton switch for mode of operation either percent distortion (% DIST) or ac volts (VOLTS). 2.4.1.5 FILTER: There are three switch selectable filters: 40dB/decade, 400Hz, HIGH PASS, for reducing the affects of line (to be used at input frequencies greater than 1kHz); 60dB/decade, 30kHz, LOW PASS, which provides band limiting requi