Rohde_Schwarz CMT Radiocomm._Tester_Service_Manual 电路图.pdf

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1、 ) I, ) / VOLUME 1 . rVI RADI C TESTER C T 802.2020. 802.2020.54 u I jf;liltltl,;eI$!t $ $ . I/il (! t! () _ (J I 1 st Modulat Generator. . . . . . 0. . An Un i t (;j III Ill I $- e (f! IJ! I 6!J $ Po w e r P a G e (l i!/I $ Q Ii $ o e Gee e 0$ 6 0 E! to e, Front Panel Oscillo . l.ons f 0 4. e 0 tI:

2、 e Ii? Q 0 0 1% $ If; 0 $ (1) 0 $ 6 Il 0 III (!J Mechanic Opening the Instrument . Removing Plug-in Modules . Removing the Power Pack . Removing the lEC Bus/Control Interface Option CM-B4 and the Autorun Control inter In terf ace Opt ion CM-B 5 . Removing the Attenuation Set . Removing the Oscillosc

3、ope . Removing the Front Panel . Page 4.1 4. 1 4. 1 4.1 4. 1 4.2 4.3 4.3 4.3 4.4 4.4 4.4 4.5 4.5 4.5 4.5 4.6 4.6 4.6 4.6 Testing and Adjustment . 4.9 A.djusting the Power Pack . 4.9 V Operating Voltage . . 4.9 4 V Operating Voltage . 4.9 Adjusting the Digital Unit . 4.10 Adjusting the RF Oscillator

4、. 4.10 Frequency Adjustment . 4.10 Level Adjustment . 0 4.10 Adj ust ing the Output Stage . 4. 11 Level Adjustments . 4. 11 Adjusting the Modulation Depth . . 4.11 Adjusting the Analog Unit . 4.11 Adjusting the LO Conditioning . 4.12 Adjusting the RF Amplifier, FM . 4.12 Adjusting the RF Amplifier,

5、AM 4.12 Adjusting the FM Demodulator . 4.12 Adjusting the AM Demodulator . 4.13 Adjusting the CCITT Filter . 4.13 Adjusting the Distortion Control . 4.14 Adjusting the 1-kHz Notch Filter . 4.14 Adjusting the 990-Hz Notch F ter . 4.14 Adjusting the 1010-Hz Notch Filter . 4.15 Adjusting the Power Disp

6、lay . 4.15 Adjusting the At tenuation Set . 4. 15 Adjusting the Oscilloscope . 4.15 Adjusting the Horizontal Beam De ection . 4.16 Opt ion S III t:I $ III III r.1 I l I! (II e II) ( $ eo, (i 0 0 (I IllI 9 oIj; 4 (!J 1 6 4.4 Troubleshooting . 4.17 802.2020.52 9 E-2 RadioFans.CN 收音机爱 好者资料库 Contents 5

7、Service Manual for the Indi Pa, Un Unit 1st Modulation RIr Oscillator Output Stage Attenuation Generator Modu . . e, inc1-Reference Oscillator CMT-B 1 . . e 10 ex 1 2 3 4 5 6 7 E-1 Gener Serial data transmission pi ace on three 1 ines: re us an extern just or test ual pl ug-in modul es t s STROBE. e

8、 ta must be p in to e ic strument. e t i di ram data transmiss is shown ow. STROBE The data on the DATA line are ansferred to the parallel/seri converter with each rising edge of the CLOCK pulses; a subsequent STROBE pulse enables the data at the converter outputse The fol- lowing BASIC program show

9、s how the user port the PUC can dress the module: 10 POKE 59259,255 20 OIM A(20) 30 A(1)=O:A(2)=1 . 40 FOR lT020 50 POKE 59471,A(I 60 POKE 59471,A(I)+2 70 NEXT 80 POKE 59471,4 90 POKE 59471,O:END Set user port Number of individual data bits, 20 in this case Define individual data Read in data; Line

10、with significance 2 = DATA, significance 21 = CLOCK Output STROBE puse on line with significance 2 41 1 wi modulation generates from 500 to 1000 MHz which is ies three sel oscillators Three phase by loops setting ut ( PLL) The rna a 1 OMHz to whi t oscillator ( oscillator e- s :Ui as 1 inked The 10

11、reference equency justed 2 kHz and whose is re ence frequency tors. 100-MHz is a cryst ncy, for the coarse ram uces which can be ad- ed by a tor of 100, PLL of the RF oscilla- If the Duplex Modulation Meter option CM-B9 not fitted, the RF synthesizer is operated as a generator in the receiver test a

12、nd as a m ing oscillator in the transmitter test. Information on voltages and on the locking of the PLLs is ssed to the control- ler via the analog unit test purposes and trouble- shooting. The output stage divides the frequencies provided by the RF syn- thesizer such that a frequency range 31.25 to

13、 1000 MHz is co- vered. Appropriate filters are connected in series with the fre- quency div iders to ensure that the harmonics ratio required is attained. Frequencies M is en- The an og unit consists of llowi funct uni ts: RF am- plifier, LO conditioning, demodulators, AF condition and DC amplifier

14、. The RF signals to be measured are regulated to a constant level in the RF amplifier according to the type of modulation and then routed to the RF frequency counter and the mixer. The LO conditioning amplifies the signals from the output stage to the level required for the mixer. Frequencies below

15、31.25 MHz are divided to generate the IF of 455 kHz for signal frequencies up to approx. 1 MHz. A generator with amplitude modulation is in- tegrated self-testing. The demodulators contain the IF amplifiers, the AM and FM/llM de- modulators and filters required to suppress the IF. The AF conditionin

16、g weights the demodulated signal and the signal from the AF VOLTM input according to the measuring requirements; various filters (300-Hz HP, CCITT filter, 150-Hz HP) can be con- nected as required (rms or peak values). The signal to be mea- sured is regulated to a constant rms value for distortion m

17、ea- surements and subsequen freed from the wanted signal in a notch filter. The rectifiers (peak v ue and rms value rectifiers) are conta ed in the DC amplifier. A DC multiplexer connects the voltages supplied by the other modules to a selectable DC amplifier which passes the signal to the A/C conve

18、rter incorporated in the digi- tal unit. 802.2020.52 4.2 The digit unit consists of the lowing function units: RF counter, AF counter, AID converter and controller. The RF counter counts the r 1 to 1 000 MHz to generate LO from AF counter counts well as sign s in put AF VOLTM. ler s idu modules are

19、STROBE). Power fa I of a s Hz appl i ete instrument. I data via. seri data I s th an it al bat n to to ( i DATA, t e when ensures at data are o not lost power failure instrument is as in- the p or The power pack supplies the strument with the operating vol- tages of +5 V, +12 V, +15 V, -15 V and +24

20、 V. The voltages are generat using a switched-mode power supply so that the instru- ment can also be operated using standard car bat ies. When con- nected to the AC power supply (I a transformer reduces the line voltage to the voltage requi for the switched-mode power supply. The instrument operates

21、 in STANDBY mode if the power pack is switched off from the front panel; all voltages are then switched off except the +12 V supply which is used the 10-MHz crystal oven and the STANDBY logic. Fuses are provided on the input side to protect the power pack. STANDBY mode is automatically switched on i

22、f one or more voltages on the secondary side are short-circui ted wi th each other or to ground or if the power pack is operated without a secondary load. All keys required to operate the instrument as well as the loud- speaker potentiometer and the spin whe for fast adjustment of the parameters are

23、 locat on the front panel. The set parameters and the resul ts are output on LCDs connected to the front panel via conductive rubber contacts. The loud- speaker amplifier is also mounted on the panel wi th the loud aker control. A ribbon cable connects the front panel units to the motherbo and the d

24、igital unit. 802.2020 52 4.3 E-1 The attenuation set contains the at for attenuating the RF synthesizer I ators in which the major part of the into heat. The connection between attenuators is via a 50- power d , an unit rear p are connected. ing RE d set during mechan scre onto the attenuation set u

25、ates the voltages the via a ribbon c e. uator connected to relays as well as power attenu- applied power is converted power attenuators and the star arr ement to which RF-30 0 i on to tect the attenuation to tect power. A B s the attenuat set The is connec to The oscil scope enables visu display of

26、the demodulated s nals, the beat signal and externally applied signals. The voltages required for the oscil scope tube, the blanking am- plifier and the de ection amplif are generated by a switched mode power pack with an operating voltage of 24 V. The deflection coefficient.s and the operating mode

27、 are read from the digital unit into RAMs, read out by D/A converters and writt.en as ssa- jous figures on the screen in the form of numbers, let.t.ers and arrows. The oscilloscope is powered via ribbon cables which are routed to t.he front. panel. The function descriptions of the options are contai

28、ned in the re- spective service manuals (Section 5). 802.2020.52 4.4 E-1 Exce the front panel, cil scope, the CMT modules pairs can therefore be carr! be comple y replaced power pack, at tenuat set and os- are designed as pl ug-in cards. Re- out rapidly or the faul c can e ectr ic connections are co

29、mmon mothe Loosen the feet (marked t. Remove the reare s are rout es. coaxi p e via es. The au: 1S own out via Phill ips screws the rear used to secure the A in Fig. 4-1); the capt screws remain in the the feet and slide out the top and bottom panels to Caution: The power plug must be disconnected b

30、efore removing the modules. These modules are secured by two rails at the sides next to the motherboard. Loosen the Phillips screws marked A in g. 2 and press towads the rear using a suitable tool inserted into bracket B. Disconnect any coaxial and ribbon cables present and remove the modules from t

31、he instrument. Note: If the IEC Bus/Control Interface option CM-54 and the Autorun Control/Printer Interface option CM-BS are pre- sent, these must be removed before removing the digit unit module (see Section 4.2.4). Disconnect plugs X60, X61 and X70 from the motherboard. Loosen the five Phillips s

32、crews marked C and D in g. 4-1 and remove the power pack from the arne. Ensure that the cables leading from the power pack are not subjected to stress which could break the conne lead-ugh f ters. 802.2020.52 Loosen the Ph lips screws on the rear of the instrument (marked D and E in Fig. 1) and remov

33、e the option( s) towards the rear multi e connectors of the digital unit. Unscrew two SMA j t and pull off connectors two coaxi from c connectors. es with a id e by Fig. at tenuat se t th the heat si which are fi screws and remove is mounted to assis ur screws, two 2). Loosen at s drive is fitted on

34、 screws. Be removing the board, overtemperature sensor. wi nuts (marked C in attenuat set th attenuat solder set using six two wires to the Note: The attenuation set must not be opened; the internal com- ponents consist of thin-film substrates which can only be replaced in the factory. Loosen the he

35、xagon socket screws of the rotary knobs on t panel and remove the knobs. Loosen the six screws with which the inscription panel is secured (two screws in the centre between the displays). Loosen the screws marked A in Fig. 4-3. Disconnect the two ribbon cable pI ugs and the coaxial connector X605 fr

36、om the analog unit module. The oscilloscope assembly can now be re- moved from the front. Remove the inscription panel as described in Sect 4.2.6 and loosen the screws marked B in Fig. 4 Disconnect the three rib- bon cable connectors and remove the panel. 4 6 Figs. 4-1 to 4-3 show the screws to be l

37、oosened to remove the modules. Fig. 4-1 A ( B c Fig. 4-2 802.2020.52 4 7 A B Fig. 3 802.2020.52 B B B 4.8 Exact testing out according to the manual re re necess the instrument specificat should carried Section 3.2 in the Operating Manual. Each test s to a ssible justment. Renewed testing is low ng j

38、ustments. 1 carr or :If out justments on e, y i c justments, ensure to i unin ues can e measurement errors. es uld ser out. If a module must a fundament unit justment as scr outs (e.gw d Sect 5. us justment is instruments uni t), c e modules if this viously of justments module to module and also wit

39、h:ln ensures that the adjustments do not fect one another; is nevertheless possible, re rence is made to the pre- required setting. Switch on instrument Adjustment po : X61 on motherboard Adjustment value: Adjust to 5.3 V 10 rnV using R12 Setting: Switch on instrument Adjustment int: X61 on motherbo

40、ard Adjustment value: Adjust to 24 V +100 rnV/-O mV us R56 802.2020 52 4.9 Setting: + Switch on instrument ustment : + X58/A21 on ustment just to 10 V 1 mV usi 09 lout mod e connect to e usi n Settings: Adjustment Adjustment Settings: Adjustment e. + Receiver test + Frequencies as in following table

41、: Frequency Trimmer 500.001 MHz C21 655.001 MHz C51 825.001 MHz C81 point: + X9/2 value: , Adj ust to 2.5 V DC 100 mV using C81 + Receiver test + Frequencies as in following table: Frequency 575 MHz 730 MHz 900 MHz int: + X310 Trimmer R49 R79 R109 er e. 1 p 1 , ustment : + Adjust to 0 dBro 3 dB usin

42、g R49, R79, R109 802.2020.52 E-2 Note: Check stage. justment 4.3.3.2 before adjusting the output Remove e connect usi c e. j ustment: $ e + Ie 1 Fre-Level Tr justment ue mer 100 MHz +13 dBm 14 13 dBm O.OS dB *: 1,00 MHz -16.9 dBm R4S2 .9 dBm 0.05 7.9 MHz +13 dBm R641 13 dBm O.OS dB Ie 7.9 MHz -16.9

43、dBm R663 .9 dBm 0.05 dB ustment point: + X401 or RF IN/OUT on the front panel Compare 1 using RS14. of 13 dBm at 1 GHz and 330 MHz and t average + Rece test + Frequency 100 MHz + Level 0.1 dBm + Modulation 80% AM + .AF =: 1 kHz ustment point: + X401 or RF IN/OUT on the front 1 Mj value: + Adjust to

44、80% AM 0.1% AM using R503 + Remove the module cables . .,. Open module. 802.2020.52 the CMT and connect us ing the 4. 11 apter E-1 ings: + Transmitter test + Fixed equency 15 MHz ustment : + D100/3 ustment us 02 TTL lev esent at, : + Transmitter test + Apply 500 MHz, 20 mV to + at: FM : + X610/50 n

45、Adjustment value: -1 Adjust to 150 mV 5 mV using 7 Note: The adjustment 4 + 1 1: + Adjust to 1 Vrms 1 mV us 43 + N450/1 just to s 2 usi 42 + Receiver test Apply 1 kHz, 1 Vrms with low distortion 32 MHz) sent at X608 an og unit) ? Demodulated signal at BNC connector DEMOD ? No display of meas v ues:

46、AF voltmeter, RF tmeter, demodu- lation, distortion ? AID (d ampl ifier (an 802.2020.52 i uni t) og un! t) Re ace atte- nuat set RF counter ( d it unit) RF amplifier (anal uni t) Yes LO conditioning (analog unit) RF oscillator, output stage, duplex modul at meter Demodul ators (analog uni t) Fa t in

47、 analog unit (DC ampl ifier, AF conditioning) 419 R 44Fnn Liste mechanischer T eile List of mechanical parts Bilder zur Liste mechanischer Figures pertaining to list of mechanical parts Liste zu den Bildern st Figs 4-10 . :3 L . St Be s reibung S Nr. zeichen zahl - -_ . -=-,- -=- - No. Unit/ signation S No No - 1 1 MZ Haube 1/1 50 802.2537 r, 2 1 MZ Hau