krohnhite Model3500 电路图.pdf

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1、SOLID STATE BAND-PASS FILTER MODEL 3500 SERIAL NO. OPERATING AND MAINTENANCE MANUAL KROHN-HITE CORPORATION AVON INDUSTRIAL PARK I 255 BODWELL STREET I AVON, MA. 02322 TEL. (617) 580-1660 TWX 710-345-0831 1984 RadioFans.CN 收音机爱 好者资料库 Contents Section I 2 3 4 5 6 Figure I 2 3 4 5 6 7 8 9 10 I I CONTEN

2、TS GENERAL DESCRIPTION OPERATION. CIRCUIT DESCRIPTION INCOMING ACCEPTANCE AND INSPECTION MAINTENANCE CALIBRATION AND ADJUSTMENT . ILLUSTRATIONS Model 3500 Filter Normalized Frequency Square Wave Response Normalized Attenuation Characteristics Normalized Phase Characteristics Front and Rear Panels Si

3、mplified Schematic Diagram Test Point Voltages Top and Side View of Chassis Schematic Diagram PC307 Page I 7 9 12 15 19 Page ii 3 4 4 5 6 9 16 18 Foldout Foldout i RadioFans.CN 收音机爱 好者资料库 Filter 3500 Model 3500 . Figure 1. Model 3500 Filter ii RadioFans.CN 收音机爱 好者资料库 Section 1 -General Description S

4、ECTION 1 GENERAL DESCRIPTION 1.1 INTRODUCTION The Model 3500 Filter, shown in Figure 1, is a variable, electronic band-pass filter that operates at frequencies from 20Hz to 200kHz. The filter consists basically of an input amplifier, a variable high-pass section, a variable low-pass section, and an

5、output amplifier. The high-pass and low-pass sections are con nected in series. The overall gain of the Filter is unity(Odb). The cutoff frequencies of both the high -pass and low-pass sections can be adjusted independently over the full frequency range of 20Hz to 200kHz. An optional rack-mounting k

6、it, (Part No. RK-38) is available from Krohn-Hite, for installing the unit in a standard 19 rack spacing. 1.2 GENERAL SPECIFICATIONS Frequency Range Continuous coverage from 20Hz to 200kHz for both high cut-off and low cut-off fre quencies independently. Frequency range is covered by separate calibr

7、ated dials and four-decade band switches. Center frequency and width of pass band in band pass.mode are continuously adjustable over the entire frequency range. BAND MULTIPLIER FREQUENCY (Hz) 1 1 20 -200 2 10 200 -2, 000 3 100 2, 000 -20, 000 4 lK 20, 000 -200, 000 Frequency Dials Each dial is engra

8、ved and individually hand-calibrated with a single logarithmic scale reading directly in cycles per second, from 19 to 210. Dials are 2 inches in diameter with an effective scale length of 6 inches per band, giving a total effec tive scale length of 24 inches for the range of 20Hz to 200kHz. Accurac

9、y of Cut-off Frequency Calibration 10% with Response switch in max-flat (Butterworth) position; les s accurate in Low QII position. Relative to mid-band level, the filter output is down 3db at cut off in max-flat position, and approximately 12db in II Low Q position. Filter, 3500 Bandwidth Continuou

10、sly va r ia bl e within the cutofffrequencylimits of 20Hz and 200kHz. For minimum pass -band (Butterworth response) the two cutoffs are set to the same frequency, resulting in an insertion los s of 6db at that frequency, with 3db points at factor s of .8 below it and 1. 25 above it. Response Charact

11、eristi cs Choice of 4 pole Butterworth (maximally flat response) for frequency domain opera tion and Low Q (damped response) for transient-free time domain operation, se lected by means of a switch on rear of chassis. Pass-Band Gain Zero db l db in pass band. Input Characteri sti cs. Impedan ce Appr

12、oximately 10 megohms in parallel with 50 pf. Maximum input amplitude: 5 volts rms up to 2MHz. Maximum dc component: 00 volts. Output Characteristics, Impedance Approximately 50 ohms. Maximum Voltage +7 volts peak. Maximum Current +5 rna peak. Internally generated hum and noise: Less than 200 microvo

13、lts. (Slightly higher for 400 Hz operation. ) Attenuation Slope Nominal 24db per octave each side of pass-band. Maximum Attenuation Greater than 60 db. Controls Front panel; LOW CUT-OFF FREQUENCY dial and multiplier switch. HIGH CUT OFF FREQUENCY dial and multiplier switch. POWER OFF-ON switch. Rear

14、 panel; RESPONSE switch, GROUND switch, 115/230V LINE switch. Terminals Front panel, two BNC connectors, one for INPUT and one for OUTPUT. Rear of chassis, two BNC connectors, one for input and one for output. An additional multi purpos e binding post for CHASSIS GROUND is provided on the rear panel

15、. An AC power receptacle with detachable line cord is also provid ed. Power Requirements 105-125 or 210-250 volts, single phase; 50-400 Hz, 10 watts. Hum and noise are increased by a factor of approximately two for 400Hz operation. 2 Section I -General Description Fuse Protection 1/8 ampere slow-blo

16、w for 11 5 volts, 1/16 ampere slow-blow for 230 volts. Dimensions and Weights Model Overall Dimen sion s (inc hes) W e ig ht (lb s.) 3500 8 1/2 wide I 3 1/2 high I 13 deep 9 net 114 shipping 1.3 FILTER CHARACTERISTICS Bandwidth Adjustment The flexibility of adjustment of bandwidth is illustrated in

17、Figure 2. Band-pass operation in the MAXimally FLAT or Butterworth m od e for two different barid wid th s is illustrated by cu r ve s A and B. Cu rve B sh ows the minimum pa ss-band width obtained by setting the two cut off frequencie s equal. In this cond ition the insertionlossis 6db, andthe - 3

18、dbcutofffrequencies oc cu r at0.8and 1.25 timesthemid-bandfrequency. Theminimumpass-bandfora 0dbinsertionloss is s hown by cu r ve A with the cutoffs s et at 0.5 and 2 times the mid - ban d frequency. 0 -6 -10 :0 :g -20 z 0 - 30 : -40 z w -50 I -60 -70 -80 .01 .02 .04 .06 .1 .2 .4.6 2 4 6 10 20 4060

19、 100 fI . A V I 8 , 1 / J If , 1 / / , / I 1 I V i / 1/ / NORMALIZED FREQUENCY Figure 2. Normal iz ed Frequency Transient Response Thefrequencyresponsecha r acte r i s ticofthisFiltercloselyapproximates afourth order Butterworth with m ax im al flatnes s, id eal for filtering in the frequency do m a

20、 in. For puls e o r transient s ignal filtering, a r e sponse switch is p r ovid ed to change the frequency re sponse to Low 0, optim um for transient-free filte r ing. Figure 3 shows a comparison of th e Filter output response in the se modes to a squa r e wave input signal. 3 Filter, 3500 (A) (E)

21、Figure 3. Square Wave Respon s e Cutoff Response The attenuation cha r a cteristics of the Filter are shown in F ig u re 4. With the r e sponse s w itch in the MAXimally FLAT o r Butterworth m ode, the gain, a s shown by the solid cu rve , is virtually flat until the -3db cutoff frequency. At approx

22、i m a tel y twotim e s thecutofffrequencytheattenuationratecoin c id es with th e 24 db per octave straight line a s ymptote. In the Simpl e R C m ode, optimum for tran s ien t - f r e e filtering, the dotted line show s that the ga in i s down approx imately 12 dbatcutoffandr e aches 24 dbperoctav

23、e attenuationrate a t fivetim e s thecutoff frequency. Bey ond thi s frequency the filter attenuation r a t e and max i mum attenua tion, in either m od e, are identi c al, o - 6 -12 CD 3 A .5 .6.7 89 I21 3 4 5 6 789102 f L OR.b. fH f 1-_-. r-. r-.I 1, 1r-. i I I I I 1 I I f H =HIGH CUTOFF FREQUENCY

24、 . I I f l = lOW CUTOFF FREQUENCY . I I I I I J a - 18 l: o a: -24 -.J LL - 3 0 -36 -42 Figure 4. Normalized Atte n uation Characteristics 4 Section 1 -General Description Phase Response The phase angle at any frequency is the sum of the angles due to the high-pass and low-pass sections of the Filte

25、r. Figure 5 gives the phase characteristic for either section in degrees l ead (+) or lag (-), a s a function of the ratio of the operating frequency f to low cut-off frequency for high-cutoff frequency f H. L The solid curve i s for the maximally flat or Butterworth m ode and the dotted curve i s f

26、or Low Q. +360 .4 .0 .6 .7 .8 .9 I. 2 s 6 7 8 91042 :- I - .-; , I- , ., i , . -, r .-, - - , r-.-. -, , u u o .J :I: + 120 240 + 60 300 o 360 I INPUT FREQUENCY If I LOW CUTOFF f L OR HIGH CUTOFF I H Figure 5. Normalized Phase Characteristics Example Determine the phase shift through the filter, in

27、the maximally flat or Butterworth mode with the low cutoff (fat 200 Hz, the high c utoff (fH) at 600 Hz and an input L) frequency (f) at 300 Hz. Phase shift due to low cutoff (fL) 300 = = I .5 200 from Figure 6 1. 5 =+ 1100 Phase shift d ue to high cutoff (fL) 300 . 5 600 from Figure 6 .5 = _80 0 To

28、tal phase shift 5 - - 0-t - t f%j t=: . r r (l) -j - v. U1 - 0 0 FRONT VIEW REAR VIEW FI GURE 6. FRONT AND REAR PANELS CD POWER SWITCH (ON / OFF) INDICATOR LIGHT INPUT CONNECTOR (BNC TYPE) oOUTPUT CONNECTOR (BNC TYPE) MULTIPLIER SWITCH (HIGH PASS) MULTIPLIER SWITCH (LOW PASS) (!) FREQUENCY DIAL (LOW

29、 CUTOFF) FREQUENCY DIAL (HIGH CUTOFF) 115/230V LINE SWITCH ) OUTPUT CONNECTOR (BNC TYPE) INPUT CONNECTOR (BNC TYPE) liSA SLO-BLO II7V 12 FUSE 1/16A SLO-BLO 234V POWER RECEPTACLE CHASSIS GROUND CONNECTOR (BINDING POST) GROUND SWITCH (FLOATING / CHASSIS) RESPONSE SWITCH (MAX FLAT / LOW Q) POWER TRANSF

30、ORMER NAMEPLATE Section 2 -Operation SECTION 2 OPERATION 2.1 INTRODUCTION The Filter i s adjusted and checked carefully before shipment t o insure that it meets all specifications. It is then aged and again tested to be sure that it is ready for use. The Filter is shipped complete, and after unpacki

31、ng, is ready to be turned on and used. Unpack the Filter carefully and inspect it for damage that may have occurred during shipment. Check the case for damage, and check for loose sub-assemblies and parts. Check all front panel controls for freedom of operation. The recommended operating procedure i

32、s described below. The r m s voltage of the input signal s hould not exce ed 5 volts. The de component of the input signal should not exceed 100 v olts . 2.2 FRONT PANEL CONTROLS The front panel controls con s i st of two identical frequency dials and associated multiplier switches used to set cut-o

33、ff frequencies, a power on-off switch, and an indicator light. Each frequency dial 1 S calibrated with a single logarithmic scale reading directly in cycles per second from 19 to 210. The dials are two inches in diameter with an effective scale length of approximately six inches per band, giving t o

34、ta l effective scale length of approximately 24 inches for the 20Hz to 200kHz frequency range. The left-hand dial (LOW CUT-OFF FREQUENCY) and band multiplier switch select the low cut-off frequency, and the right-hand dial (HIGH CUT-OFF FREQUENCY) and multiplier switch select the high cut-off freque

35、ncy. Each of the two multiplier switches has four positions, covering the frequency ranges as shown in Section 1. 2. 2.3 REAR PANEL CONTROLS The rear panel cont r ol s c on s i st of a RESPONSE switch, a GROUND switch, and a 115/230V LINE switch. The RESPONSE switch is us ed to select either a Butte

36、rworth (max-flat) or a Low Q response. The GROUND switch is provided to disconnect the signal ground from the chassis. The LINE switch i s used when changing from 115V to 230V AC operation. 7 Filter, 3500 2.4 OPERATION To operate the Filter, proceed as follows: a. Make appropriate power connections

37、as described in Section 2.6. b. Make appropriate connections to INPUT and OUTPUT terminals of filter. c. Set cut-off frequencies by means of the band multiplier switches (CUT OFF FREQUENCY) and the frequency dials. d. Turn POW ER switch to ON. NOTE The left-hand band multiplier switch and frequency

38、dial are used to select the low cut-off frequency and the right-hand controls select the high cut-off frequency. The minimum pass -band is obtained by setting the high cut-off frequency equal to the low cut-off frequency. 2.5 TERMINALS INPUT - A BNC type connector is provided on the left side of the

39、 front panel. A parallel BNC coaxial connector is located on the rear of the chassis. OUTPUT - A BNC type connector IS provided on the right side of the front panel. A p a.rall e.l BNC coaxial connector is located on the rear of the chassis. CHASSIS GROUND -An additional combination-type binding pos

40、t is provided on the rear panel. AC INPUT -A power receptacle with detachable line cord is located on the rear panel. 2.6 LINE VOLTAGE AND FUSES The Filter may be operated from an AC power source of either 105-125 volts, 50-400 Hz, or 210-250 volts , 50-400 Hz. A 115/230V LINE switch, located on the

41、 rear panel, selects the filters mode of operation. When the AC line is 115V, mo ve the LINE switch to the 115V position. In this mode, a 1/8 ampere slo-blo fuse must be used. When the filter is to be operated from 230 VAC, move the LINE switch to the 230V position, and replace the fuse with a 1/16

42、ampere slo-blo type. 8 - - - - Section 3 -Circuit Description SECTION 3 CIRCUIT DESCRIPTION 3.1 INTRODUCTION As shown below in the simplified block diagram, Figure 7, the filter consists of an input amplifier, for isolation; a four pole low-pass section (high cutoff frequency), with four R. C. filte

43、r networks which are adjustable by means of a gauged potention meter assembly and bandswitch; and a four pole high pass section (low cut off fre quency), with four R. C. filter networks and a similar ganged potentionmeter as sembly and b ands wit ch, Both cutoff frequencies are tuned continuously wi

44、thin each decade by the potentionmeter assemblies. The capacitors are tuned in decade steps by the bandswit ch, INPUT r: f-.-:;H-j1-1Q20 6 JI QI02 Q205 Q207 MAX FLAT - 0 Q203 Q208 I LOW Q I - - I I J I OUTPUT Q301 Q304 -H Q302 Q305 I IMAX FLAT o Q303 Q 306 f-+-O-L LOW Q Figure 7. Simplified Schemati

45、c Diagram 9 Filter, 3500 3.2 DETAILED DESCRIPTION 3.2.1 Input Amplifier The input signal i s capacitor coupled through CIO I to the input a m plifie r cons i sting of Q 10 1 and Q 102 The input impedance determined by RI O1 is 10 megohms . The highinputimpedanceoftheF.E.T. QIO1 isnegligible. Theinpu

46、tamplifieri s provided to isolate the input signal and supply a low impedance driving s ou rce for the fir st R. C. network. 0 3.2.2 High Pass Section The high pass section consists of a pair of two pole filters, each a djusted to pro vide the proper Butterworth response characteristics when cascade

47、d. Buffer am plifiers are used to isolate the two pole R. C. networks. The Buffer Amplifier, consisting of Q20 1 and Q202, folIowing the first 2 pole network provides isolation and drives the next R. C. network. Q203 furnishes feedback to the emitter follower stage for corner frequency peaking. The

48、signal then enters another Buffer Arnpli fier stage consisting of Q204 and Q205, again providing i s ol a tion and a low imped ance source to drive the next R. C. n etwork. Q206 and Q207 perform as a buffer amplifier between the high-pass and low-pass sections with Q20 8 providing enough feedback to Q204 to produce the correct Butterworth response. With switch 5901 in the grounded position, the feedback is reduced to produce the Low Q (damped response) f