HP-202A-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 SPECIFICATIONS r FREQUENCY RANGE: 0.008 to 1200 cps in five decade ranges with wide overlap at each dial extreme. DIAL ACCURACY: Within *2% from 1. 2 to 121q on dial; *3% from . 8 to 1.2. FREQUENCY STABILITY: Within 4% including

2、 warm-up drift and line voltage variations of *lo%. OUTPUT WAVEFORMS: Sinusoidal, square, and triangular. Selected by panel switch. MAXIMUM OUTPUT VOLTAGE: At least 30 volts peak-to-peak across rated load (4000 ohms) for all three waveforms. (10.6 volts RMS for sinewave. ) FREQUENCY RESPONSE: Consta

3、nt within *0.2 db over entire frequency range at rated output and load. lNTE RNAL IMPEDANCE : Approximately 40 ohms over the entire range. DISTORTION: Less than 1% on all ranges except X100. Less than 2% rms on X100. OUTPUT SYSTEM: Can be operated either balanced o r single-ended. Output system is d

4、irect-coupled; dc level of output voltage remains stable over long periods of time. DC adjustment available on front panel. HUM LEVEL: Less than 0.05% at rated output. SYNC PULSE : 10 volts peak negative, less than 5 microseconds duration. Sync pulse occurs at crest of sinewave and with correspondin

5、g positions on other waveforms. POWER: Operates from ll51230V -+lo%, 5011000 cycles source. Requires 17 5 watts. DINENSIONS: Cabinet Mount: 20-314 wide, 12-112 high, 14-112 deep. Rack Mount: 19 wide, 10-l/21qhigh, 14-11 4 deep. WEIGHT: Cabinet Mount: 48 lbs; shipping weight, approximately 84 lbs. Ra

6、ck Mount: 36 lbs; shipping weight, approximately 74 lbs. ACCESSORIES AVAILABLE: For rack mount style: End Frames with handles for bench use. Specify No. 17 End Frames. CONTENTS SECTION I GENERAL DESCRIPTION Page 1 . 1 General . 1-1 SECTION II OPERATING INSTRUCTIONS 2 . 1 Inspection . . . . . . . . .

7、 . II . 1 2 . 2 Controls and Terminals . II . 1 2 . 3 230-Volt Operation . . . . . . . 1 1 . 1 . 2 . 4 Operation . . . . . . . . . . II 1 . . 2 . 5 Single-Ended Output II 2 . . . 2 6 Balanced Output II 2 . . . . . . . . . . . . 2 7 Sync Out 11-2 SECTION m THEORY OF OPERATION 3 -1 General . . . . . .

8、 . . . . . III 3 . 2 Bi-Stable Circuit . . . . . . . . III 3 . 3 Linear Integrator . . . . . . . . III 3 . 4 Sine Synthesizer and Function Selector Switch . . III 3 . 5 Output System . . . . . . . . . III 3 . 6 Sync Pulse Output . . . . . . . . III 3 - 7 Powersupply . . . . . . . . . III SECTION IV

9、MAINTENANCE General . . . . . . . . . . . IV-1 Power Supply . . . . . . . . . IV . 1 Function Generator (bi-stable circuit and integrator) . IV . 2 Sine Synthesizer and Function Selector . IV . 2 Output Amplifier . . . . . . . . IV . 3 sync Out . . . . . . . . . . IV . 3 Tube Replacement . . . . . .

10、 . . IV . 3 Tube Replacement Chart . IV . 4 Power Supply Regulator Adjustment . N . 4 Theory of DC Balance and Distortion Adjustments . IV . 5 DC Balance and Distortion Adjustments . . . l V . 5 Adjust Squarewave Amplitude . I V . 8 Frequency Ratio and Calibration Procedure . . I V - 8 Replacement o

11、f R58 Potentiometer . IV . 9 SECTION V TABLE OF REPLACEABLE PARTS 5 . 1 Table of Replaceable Parts . V . 1 Sect. I Page 1 1-1 GENERAL The Model 202A Low Frequency Function Generator is a compact, convenient, and versatile source of transient-free test voltages between 1200 and .008 cycles per second

12、. It is useful for any general purpose low frequency testing application and is particularly valuable in the testing of servo systems, geophysical equipment, vibration and stability char- acteristics of mechanical systems, electro-medical equipment, and for the electrical simulation of mechanical ph

13、enomena. Three types of output wave- form are available; sine, square andtriangular. Also, a sync output pulse is available for external use. The Model 202A Low Frequency Function Generator contains a type of relaxation oscillator that is par- ticularly advantageous for the generation of very low fr

14、equencies. Both a triangular and a squarewave voltage function of time are inherent in the oscillating system. Also, a sinewave function is produced by synthesis from the triangular wave. Output amplitude and distortion are virtually in- dependent of the frequency of operation. This type SECTION I G

15、ENERAL DESCRIPTION of oscillating system in inherent a constant am- plitude device so that no A. V. C. system, with as- sociated delay in stabilization after frequency changes, is required The frequency range from .008 to 1200 cycles per second is covered in 5 bands. The frequency dial is linear. Th

16、e output system is a direct-coupled amplifier system designed for either single ended or balanced output. It has good stability with respect to direct current in the output and very low hum level. Both the FUNCTION selectro switch and the AMPLlTUDE control are so arranged that the characteristics of

17、 the amplifier are independent of their position. The internal impedance of the output amplifier is approx- imately 40 ohms, and the unit is rated to deliver at least 30 volts peak-to-peak to a 4000 ohm load. A negative peak sync pulse of 10 volts into a 2500 ohm load is also provided. It has a dura

18、tion of less than 5 microseconds and occurs at the crest of the sinewave and at corresponding positions with the other functions. Sect. I1 Page 1 2-1 INSPECTION After the instrument is unpacked, the instrument should be carefully inspected for damage received in transit. If any shipping damage is fo

19、und, follow the procedure outlined in the Claim for Damage in Shipment page at the back of the instruction book. 2-2 CONTROLS AND TERMINALS RANGE This switch is used to select the desired frequency range to be covered by the frequency dial. FUNCTION This switch is used to select any one of the three

20、 types of output waveform. FREQUENCY This dial is calibrated directly in cycles per second for the X1 frequency range of the oscillator. The knob just below the dial escutcheon is directly con- nected to the frequency varying element. The lower knob is a mechanical vernier for fine adjustment of the

21、 frequency. AMPLITUDE This control adjusts the amplitude of the oscillator voltage admitted to the amplifier and, therefore, the output of .the instrument. This control is calibrated from 0 to 100 in arbitrary units. POWER This toggle switch controls the power supplied to the instrument from the pow

22、er line. FUSE The fuseholder, which is located on the panel, con- tains the power line fuse. Refer to the Table of Replaceable Parts for the correct fuse rating. SECTION II OPERATING INSTRUCTIONS OUTPUT This group consists of three terminals. The one marked G is connected directly to the instrument

23、chassis. The other two terminals, vertically aligned, are the OUTPUT terminals. With respect to the ground terminal each of these outputs has equal magnitude of signal, but they are 180 out of phase with each other. The internal impedance between the two OUTPUT terminals is appmximately 40 ohms. SYN

24、C OUT The Sync Out terminals are single-ended and have an internal impedance of about 2,000 ohms. Power Cable The three-conductor power cable is supplied with a three-prong plug. The third prong is a round off -set pin which provides a chassis ground. An adapter may be obtained to permit use of this

25、 plug with two-conductor receptacles. 2-3 230-VOLT OPERATION This instrument is shipped from the factory with the power transformer primaries connected in parallel for 115 v operation, unless otherwise spec- ified on the order. If 230 v operation is desired, the primaries will have to be connected i

26、n series as shown in Transformer Details on the schematic wiring diagram of the Power Supply Section. 2-4 OPERATION The following step-by-step procedure should be used as a guide when operating this instrument. 1) Turn the POWER switch to ON. Allow thirty seconds for oscillations to start. The instr

27、ument will operate nearly within specifications after a few minutes warm-up. It will be within specifi- cations after 30 minutes. Sect. I1 Page 2 2) Set the RANGE and FREQUENCY controls for the desired frequency. The frequency dial scale must be multiplied by the multiplying factor indicated by the

28、RANGE switch setting to obtain the oscillator frequency. Example: 4 (on dial scale) x .l (multi- plying factor indicated by RANGE switch setting) = .4 cycles/sec. 3) Set the FUNCTION switch for the desired output waveform. 4) Connect the equipment under test to the OUTPUT terminals. 5) Adjust the AM

29、PLITUDE Control for the desired output voltage. Because the frequency response is rated k0.2 db, the output amplitude may be mea- sured at any convenient frequency and the output level will be correct (within these limits) for any other frequency. must be connected to one of the OUTPUT terminals, an

30、d the strapped pair will then be the ground side of the output. 2-6 BALANCED OUTPUT Connect the two OUTPUT binding posts to the equip- ment being supplied. The G binding post may then be connected to the chassis of the equipment being driven. Under these conditions the internal impedance of the Mode

31、l 202A from either OUTPUT terminal to ground is 7900 ohms in series with a 1 pf capacitor (C29). A maximum dc voltage of 400 volts may be applied between either OUTPUT terminal and the G terminal without damaging the 1 pf capacitor (C29). The 40 ohms internal impedance (resistive) will shunt the imp

32、edance existing between the two signal inputs of the system being driven. Under circumstances where the connection places the Model 202A in series with a path carrying cur- rent, distortion of the Model 202A output will occur if greater than 10 ma peak current is caused to flow through the Model 202

33、A output system. NOTES When small output voltages are required it may be To minimize distortion in the output waveform, EQUIPMENT always use the lowest RANGE when the overlap of the FREQUENCY dial permits a choice. SUPPLIED - ground or no - signal point desirable to use an external attenuator. This

34、is 2-5 SINGLE-ENDED OUTPUT Figure 2-2. Balanced Output Connections The terminal marked (3 is isolated from the actual because the hum and noise in the output is nearly constant with output amplitude. OUTPVT terminals. For single-ended operation (3 2-7 SYNC. OUT The SYNC. OUT is a negative pulse of l

35、ess than 0 5 microseconds duration and at least 10 volts peak EQUIPMENT into a 2,500 ohm load. It occurs on one of the sine BEING and triangular crests and at the rise orfall of the SUPPLIED squarewave. It occurs at the positive crests with respect to one of the OUTPUT terminals and at the negative

36、crest of the other. Therefore, it can be changed by 180 with respect to the output system - - by reversing connections to the two OUTPUT ter- RO minals, which are otherwise completely interchange- able. The SYNC. OUT terminal marked G1 is FYgwe 2-L Single-Ended Output Coections directly connected to

37、 the chassis. 0 Sect. 1 1 1 Page 1 SECTION Ill 3-1 GENERAL Figure 3-1 depicts the general scheme of the Model 202A and indicates the waveforms produced. The bi- stable circuit consists of a flip-flop circuit capable of producing a square-wave output at point A, pro- vided it is triggered at the prop

38、er time. This is done by including in the bi-stable circuit, a two-way comparator circuit which produces the proper trig- gers for the flip-flop whenever the switching signal becomes equal to either the plus switching reference or the minus switching reference. The triangular switching signal return

39、ed to the bi-stable circuit THEORY OF OPERATION is that seen between points B and D. The conversion of square wave to triangular wave takes place in the integrator unit which is carefully designed to produce an accurate integral of the applied square wave. The bi-stable circuit and linear integrator

40、 are loop coupled in such a manner that the resulting relaxation oscillator is suitable for very low fre- quency operation. The sinewave output is taken from a point C between the triangular voltage at point B and the average level at point D. The resistance between B and C is fixed, and the network

41、 between C and D is a 1 OUTPUT Figure 3-1. Model 202A Function Generator - + SWITCHING REF 0 - 8+ CR12 - CRlO = OUTPUT AMPLIFIER CRIl AVE FtfH vOLT4GE FROM T O CR13 VOLTAGE FROM + SWITCHING SIGNAL + -SWITCHING REF , , , Sect. III Page 2 non-linear system which synthesizes a sinewave from the triangu

42、lar wave. This network consists of a group of biased diodes arranged in such a man- ner that at certain predetermined voltage levels they begin to conduct, therefore, providing shunt paths from C to D. Each additional shunt path reduces the slope of the triangle in the proper amount so that the wave

43、 is shaped to approximate a sinewave. This approximation is a s shown, and the degree to which a sinewave may be approached depends on the number of diodes. Thus there are available the sinewave C, triangular wave B, and square- wave A functions with respect to D to be selected and brought to the OU

44、TPUT terminals through the output amplifier. The output amplifier has a differ- ential input and push-pull output. 3-2 BI-STABLE CIRCUIT Figure 3-2 shows the details of the bi-stable circuit and includes the integrator in block form in order to indicate the bilateral connection from integrator outpu

45、t to comparator input. The portion of the diagram composed of V1, V2 and V3 is the bi-stable circuit. Actually, this circuit is a combination of two circuits. If capa- citors C10 and C13 are disconnected so that there is no possibility of inductive coupling from grids to cathode of V1 and V2, the re

46、maining circuit is the well-known flip-flop or Eccles-Jordan trigger circuit. The other circuit which appears in the bi- stable circuit is a voltage comparator known as the Multiar. The multiar is a circuit which employs a regenerative loop to produce a pulse when the two input voltages are equal. T

47、here are two of these in the bi-stable unit. One multiar is composed of V1, V3A and T2, and the other of V2, 3B and T1. The cathode of V3A and the plate of V3B are con- nected to reference voltages derived from the volt- age regulator tubes V5 and V6. The triangular. wave is applied to the plate of

48、V3A and the cathode of V3B. As the voltage on the plate of V3A rises towards the plus switching reference, V1 is con- ducting, but when V3A conducts, a negative pulse is formed on the grid of V1 which flips the Bi-Stable Unit to its other stable state and starts the voltage on the cathode of V3B tow

49、ards the minus switching Figure 3-2. Details of Bi-Stable Circuit and Switching System Bf - $ R20 4 I SEC13 * B- .0-, LINEAR - j1133! V3B I E INTEGRATOR +REF T + - -REF - T - .-. * Sect. III Page 3 reference. When V3B conducts the Bi-Stable Unit is flipped back to its original state, completing one cycle of operation. Voltage regulator tubes V5 and V6 are connected by a voltage divider from