HP-211A-Manual 电路图.pdf

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1、RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 Model 211A TABLE OF CONTENTS Table of Contents List of Illustrations and Tables Section Page Section page . I GENERAL INFORMATION 1-1 IV MAINTENANCE . 4-1 . . 1 . 1 . General Description . 1-1 4 . 1 Introduction 4-1 . . 1 . 9 .

2、Damage in Transit . 1-2 4 . 3 Cabinet Removal 4-1 . 1 . 1 1 . Power Transformer Conversion . . 1-2 4 . 5 Equipment Required . 4-1 . . 4 . 7 Trouble Localization 4-1 . OPERATING INSTRUCTIONS 2-1 . 2 . 1 . Controls and Terminals 2-1 . 2 -1 1 . Instrument Loading 2 -1 . . 2 -1 7 Ringing 2 -1 . 2 . 1 9

3、. External Sync Operation 2-1 . 2 . 2 2 . Pulses 2-3 . 2 . 2 4 . Balanced Output 2-3 THEORY OF OPERATION . 3-1 . . 3 . 1 Introduction 3 -1 . 3 . 3 . Sync Trigger 3-1 . 3 . 7 . Multivibrator 3-1 . 3 . 1 2 . Clipper Amplifier 3-1 . 3-1 5 . Power Amplifier 3-2 . . 4 . 1 2 Tube Replacement . . 4 . 1 5 A

4、djusting the Power Supply . . 4 . 2 0 Frequency Calibration 4 . 2 4 . Adjusting External Sync Sensitivity . Sync Sensitivity 4 . 2 7 . Waveform Observation and . . Measurement 4 . 4 1 . Servicing Etched Circuit Boards . . REPLACEABLE PARTS . . 5 . 1 Introduction . . 5 . 2 Ordering Information LlST O

5、 F ILLUSTRATIONS Number 2 . 1 . Common Impedance Matching Networks . 2 . 2 . Front Panel Showing Operating Controls . . 2 . 3 . Basic Output Circuit of 211A 2 . 4 . Method of Obtaining a Balanced . Output from the 21 1A 3 . 1 . Block Diagram Showing Operating . Controls of 211A 4 . 1 . Model 21 1A B

6、ottom View Showing . Amplifier and Power Supply Page Number . . 2-1 4 . 2 Model 211A Top View 2 -2 4 . 3 . Test Setup for Frequency Calibration . . . . 3 -1 4 . 4 Test Setup for Sync Sensitivity 4 . 5 . 75-Ohm Output Waveform which has . 3 -3 Defects on Positive Portion 4 . 6 . Model 211A Waveforms

7、. . . 4 . 7 Voltage and Resistance Diagram . . 3 -0 4 . 8 Multivibrator and Power Supply . . 4 . 9 Output Section . . 4 . 1 0 Range Switch Detail . . 4-2 4 . 1 1 Attenuator Switch Detail LlST OF TABLES Number Page . . 1 . 1 Specifications 1-1 . . 4 . 1 Tube Replacement Chart 4-0 4 . 2 . Test Equipme

8、nt Required . 4-1 . 4 . 3 . Troubleshooting Chart 4-3 . . 4 . 4 Calibration Chart 4-4 . . 5 . 1 Reference Designation Index 5-2 . 5 . 2 . Replaceable Parts 5 -7 Page 4-5 4-6 4-6 Section I Figure 1-1 Model 211A Figure 1-1. Model 2llA Square Wave Generator Model 211A Section I Paragraphs 1-1 to 1-5 SE

9、CTION I GENERAL INFORMATION 1-1. GENERAL DESCRIPTION. 1-2. The Model 211A Square Wave Generator is a precision wide range instrument particularly suited for use with a fast oscilloscope for video amplifier testing, permitting a rapid examination of amplifier frequency characteristics up to many mega

10、cycles. In computer, pulse code, telemetering, and similar appli- cations it offers great convenience as a variable trigger source for switching purposes. In television work it can serve as a bar generator. In highfrequency appli- cations it is valuable as a modulator source. It also finds use in te

11、stinga variety of devices such as atten- uators, filters, delay lines and audio systems. 1-3. The Model 2llAhas been designed with two out- puts, one 75-ohm output and one 600-ohm output. The rise time of the signal from the 75-ohm output is only 20 millimicroseconds, which is sufficiently fast to t

12、est the response of video devices out to approximately 20 megacycles or toprovide a high speed triggeringvolt- age of variable rate. The peak-to-peak amplitude of the signal across the 75-ohm internal impedance is 7 volts, or 3.5 volts peak-to-peakinto a 75-ohm external load. This output level may b

13、e adjusted with a 60-db step attenuator in combination with an amplitude con- trol, a particularly desirable arrangement when low output levels are required. 1-4. The second output from the generator provides 55volts peak-to-peak from a source impedance of 600 ohms. The rise time of this signal is l

14、ess than 0.1 microsecond with the output level controlled separately from that of the 75 -ohm output. Both outputs are used simultaneously. 1-5. The frequency range of the instrument, 1 cps to 1 mc, is covered in six 10/l bands. The frequency Table 1-1. Secifications Frequency Range : 1 cps to 1 mc,

15、 continuous coverage. Low Impedance Output: -3.5 volt peak across 75-ohm load -7 volt open circuit, zero level clamped to chassis; rise time less than 0.02 p e c . High Impedance Output: -27 volt peak across 600-ohm load -55 volt open circuit, zero level clamped to chassis; rise time less than 0.1 p

16、sec. Relative Phase : 180 phase difference between high and lowim- pedance output signals. Amplitude Control : Low Impedance Output - Potentiometer and 60 db attenuator, variable in 20 db steps. High Impedance Output - Potentiometer. Frequency Control: Dial calibrated 1 to 10 and decade multiplier s

17、witch. Six bands. Symmetry Control: Allows exact square-wave balance. Sync Input : Positive-going pulse or sine wave signal, min. amplitude 5 volts peak. Power: ii5/230 volts +looh, 50-60 cps, 225 watts. Dimensions: Cabinet Mount: 9-3/4 in. wide, 15-1/4 in. high, 14-5/8 in. deep. Rack Mount: t m m n

18、 m m ! B D L 11 Cabinet Mount: Net 26 lbs, shipping 38 lbs. Rack Mount: Net 25 lbs, shipping 34 lbs. Accessories Available: (Cable Assemblies) AC-16A. Four feet of RG-58C/U 50-ohm coaxial cable terminatedwith dual banana plugs. AC-16B. Four feet of RG-58C/U calbe term- inated by a dual banana plug o

19、n one end and a UG-88/U type BNC male connector on the other. $ 9 AC-16D. Four feet of RG-58C/U cable term- inated on one end by a BNC male connector. AC-16K. Four feet of RG-58C/U cable term- inated by BNC male connectors on each end. Section I Paragraphs 1-6 to 1-12 Model 211A dial is linearly cal

20、ibrated from 1 to 10. The six posi- tions on the range switch multiply these calibrations in decade steps. 1-6. For purposes of synchronization a Schmitt trig- ger circuit is located ahead of the multivibrator and is set to trigger on a minimum input sync signal of 3 volts peak, but a 5-volt peak si

21、ne wave or a positive pulse signal is recommended for practical use. The sync trigger provides a fast trigger of uniform rise and amplitude which aids in obtainingaccurate time switch- ing of the frequency multivibrator, and at the same time isolates the. multivibrator from the input wave- form. If

22、no sync signal is used the multivibrator free-runs at a frequency controlled by the range switch and the frequency control. 1-7. The multivibrator employs two type 6CL6 power pentodes with precision components in the rc timing networks. Residual variation in tubes or time con- stants may be compensa

23、ted by a symmetry control which balances the relative plate voltage swing on the multivibrator tubes. 1-8. Two outputs are taken from the frequency multi- vibrator to drive a push-pull clipper amplifier consist- ing of two 6CL6s. The clipper serves as the driver for four 6CL6 power tubes arranged in

24、 push-pull parallel as the output power stage. Local feedback is used in the power stage to stabilize the system against variations in output level with a change in frequency or range. This local feedback together with a regulated power supply assures an output essentially free from amplitude variat

25、ions over the entire fre- quency range from 1 cps to 1 mc once the output controls have been set. 1-9. DAMAGE IN TRANSIT. 1-10. After unpacking the instrument, should any shipping damage be discovered, follow the procedure described in the Claim for Damage sheet in this manual. 1-11. POWER TRANSFORM

26、ER CONVERSION. 1-12. Should it be desired to operate the Model 211A from a 210-250 volt source proceed as follows: a. Remove the two bare wire jumpers from the terminal strip located beneath the power transformer. These jumpers connect the Black to the Black-Green lead and the Black-Red to the Black

27、-Yellow lead of the power transformer primary. b. Insert a new jumper on the terminal strip which will connect the Black-Yellow to the Black-Green lead. c. Change line fuse F1 to one with a 1.25 ampere slow-blow rating. As shown in the schematic dia- gram, this alteration changes the primary winding

28、s of the power transformer from a parallel to a series arrangement. Model 211A SECTION II OPERATING INSTRUCTIONS Section I1 Paragraphs 2-1 to 2-21 2-1. CONTROLS A N D TERMINALS. 2-15. When it is desired to realize the 20 millimicro- 2-2. ON. Applies line voltage to the instrument. second rise time,

29、75-ohm output cable should be used (RG-59/U). When it is desired to drive low impedance 2-3. RANGE. Switches time constants in the multi- systems other than 75 ohms, it is necessary to match vibrator circuit to establish various frequency ranges. both ends of the output cable to its characteristic i

30、mpedance. FREQUENCY. Varies the grid 2-16. Physical arrangements for use in matchingthe to produce :lo frequency change On each instrument output to common impedances are shown RANGE switch position. in figure 2-1. 2-5. OUTPUT AMPLITUDE. The 600 5 1 control varies the amplitude of the signal at the

31、600 5 1 output OUTPUT 75n terminals. The 75 5 1 controlvaries the signal voltage applied to the 75 5 1 output attenuator. 2-6. 75 51 ATTEN. This control reduces the output 75fi (RG-59lU) * jack in 20 db steps below the level set with the 75 5 1 - OUTPUT AMPLITUDE control. - 2-7. SYMMETRY. A balance

32、potentiometer in the multivibrator plate circuit which effectively balances 75 n OUTPUT the amplitudes of the signals tothe multivibrator grids and equalizes each square wave half cycle. t 93 A (RG-62lU) 2-8. 600 5 1 OUTPUT. Two three-fourth inch spaced b binding posts which serve as the 600 5 1 out

33、put, or as - a sync out connection when 7551 output is in use. - 2-9. 75 51 OUTPUT. A female type BNC connector serves as the 75 5 1 output connector, or as a sync out 75 n OUTPUT connector when the 60051 output is in use. 2-10. SYNC IN. A female typeBNC connector to the SYNC trigger which accepts s

34、ine waves or positive pulse synchronizing signals with a minimum amplitude 7 7 : . (RG-581. of 5 volts peak. FREQUENCY control must be set at - SD-M-8 a slightly lower frequency than the desired synchro- nized frequency. Figure 2-1. Common Impedance 2-11. INSTRUMENT LOADING. 2-12. For low frequency

35、applications involving high 2-17. RINGING. impedance devices under test the output from the-211 may be taken from either the 75-ohm terminal or the 600-ohm terminal with little effect on the square wave characteristic and the calibration of the 75-ohm attenuator. 2-13. Low impedance devices, however

36、, require greater attention to impedance matching and line losses in order to preserve attenuator calibration and to pre- vent deterioration of square wave shape. 2-14. The Model 211A produces a square-wave cur- rent pulse with a peak value of 100 ma across its internal impedances. The use of the 75

37、-ohm terminal permits a fast rise square wave to be developed across the 75-ohm internal impedance, and the 75-ohm attenu- ator allows these square waves to be reduced in ampli- tude without destroying their characteristics. Matching etworks 2-18. Most video amplifiers or rlc circuits resonant below

38、 30 mc are subject to ringingwhen hitwith a fast rise pulse or square wave. Care should be taken in these cases to reduce this effect by proper matching before assuming faulty operation of the Model 211A. 2-19. EXTERNAL SYNC OPERATION. 2-20. With the instrument externally synchronized, the Schmitt t

39、rigger will control the switching of the multivibrator only when the period of the multivibrator is slightly greater than that of the external sync signal. 2-21. To permit the Schmitt-trigger output to fire the multivibrator, set the FREQUENCY control to a value slightly less than the frequency desi

40、red for sync use. This setting permits the trigger pulse to fire in a free-running recovery. 2-1 Section II Figure 2-2 Model 211A Figure 2-2. Front Panel Showing Operating Controls 00093 - 3 - OUTPUT AMPLIT LD- L- I9 1. RANGE. Select range of output frequency 6. 7552ATTEN. Attenuate voltage at 7552o

41、ut- desired. put jack in 20 db steps. 2. FREQUENCY. Select output frequency. 7. OUTPUT SIGNAL. Source impedance 7552. 3. OUTPUT AMPLITUDE 60052. Adjust output signal voltage at 60052 output terminals. 8. SYMMETRY. Adjust square-wave output voltage symmetry by viewing on cathode ray 4. OUTPUT SIGNAL.

42、 Source impedance 600% tube. 5. OUTPUT AMPLITUDE. Adjust output volt- 9. SYNC IN. Apply external signal to synchro- age at 7552 output jack. nize square-wave output signal. Model 211A Section I1 Paragraphs 2-22 to 2-29 2-22. PULSES. 2-23. The clipper amplifier and output tubes in the Model 211A oper

43、ate in a circuit designed for a 50% duty cycle. The balance of this circuit is maintained by the SYMMETRY control which balances the two outputs from the multivibrator. Any alteration of this circuit attempting to generate pulses, such as padding the SYMMETRY potentiometer to extend its range of con

44、trol, would overdrive one side of the clipper ampli- fier and output tubes beyond the 50% duty cycle factor to the eventual damage of the instrument. 2-24. BALANCED OUTPUT. 2 -25. The 21 1A can be converted to a balanced source without modifying the instrument in any way. Figure 2-3 shows the basic

45、arrangement of the output circuit. The output tubesthemselves are in push-pull but have unequal loads as shown A balanced voltage can thus be obtained by equalizing the tube loads. This can be done directly at the terminals on the panel. 7 5 n OUTPUT LEVEL CONTROL nn OUTPUT OUTPUT T ATTENuATOR figur

46、e 2-4. This additional resistance will reduce the source impedance at the lower terminals to about 75 ohms and will also reduce the voltage available from the lower terminals to approximately the same amount available at the upperterminal. At the same time the additional resistance will form a more

47、favorable time constant with the stray capacity Co at the lower termi- nals and thus speed up the normally slower rise time at those terminals until it is comparable to that of the 75-ohm output. 2-27. Figure 2-4 suggests the use either of two 75- ohm cables or abalanced 150-ohm cable for connecting to the load. In. either of these cases it is normally unnecessary to terminate the cables, so that they can be connected directly to the load. The arrangement has the advantage that it can be used with any load impedance. If cables of other impedances are used