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Racal Instruments 9915 Service Manual Download Page 54

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Summary of Contents for 9915

Page 1: ...9915 UHF Frequency Meter Service Manual Courtesy of Racal_Dana user group Click to join Racal_Dana Please enjoy responsibly G0RSQ 29th June 2015 www g0rsq co uk...

Page 2: ...mv Af 0 n 6 input A LnPUI B 40MHl 5 OMH l OH l 60MH f t cIMe mod no m011 burst displ y nlls MH z MHz kHz 01 0 1 I to gille lime fSf cOnd d bailer low 011 pO l l on _ _ Slan D IWOH 61251 U H f Frequenc...

Page 3: ...rcuit Functions 3 2 Dynamic Display System 3 2 Mul tiplex Readout 3 3 Decimal Point 3 4 Control Codes 3 4 Resistor Arrays 3 4 CHAPTER 4 TECHN ICAL DESCRIPTION Introducti on 4 1 A Channel Input 4 1 Sig...

Page 4: ...ence Output External Standard Input LF Multiplier Assembly Option MAINTENANCE List of Test Equipment Removal of Covers Transformer Voltage Selection Fuses Power Lead Power Supply Check Performance Tes...

Page 5: ...Mul tiplex Display System D 1 L Resi stor Array Control Sequence Diagram Theoretical P I N Diode Attenuator 5V Stabilizer Battery Charging Circuit Battery Power System Mains Voltage Selection LIST OF...

Page 6: ...nt and Rear Panel Assemblies Fig 1 Fig 2 SECTION 4 9915 Vol 2 Parts List 40 and 4b Main PCB Assembly Component Layout Main PCB Assembly Fig 3 Circuit A Input Amplifier Fig 4 Circuit Main PCB and Displ...

Page 7: ...fJJ9J 1 r f l f fJIJf JJ www g0rsq co uk...

Page 8: ...n pressed to Reset cnd re leased With Check Operate Reset Switch in Check position display reads Channel A Al I di gi ts set to 8 to check all segments Channel B Counter reads 1 MHz to check operation...

Page 9: ...ar panel 10 Hz to 60 MHz Better than 10 mV Ad justable by front ponel control 1 MD in parallel with 25 pF 250V r m s up to 10 kHz 50V r m s up to 100 kHz lOV r m s above 100 kHz 400V d e Channel A 4 M...

Page 10: ...tions 04A and O B 1 MHz Standard TTL output Approximatel y rectongul ar 1 MHz 500 mV r m S 1av r m s 400 Vd c Approximately 2000 0 c coupled Serial BeD output is provided at stondard TTL logic levels...

Page 11: ...erators t Aonual Spare Fuses and Supply Vo Itage Label OPTION Cl SERIAL TO PARALLEL INTERfACE Data and Control Information 8 decades of dota in 4 line BeD weighted 1248 3 Iine decimal point position p...

Page 12: ...connector By means of 3 posi ti on Mai ns Charge Battery swi tch on I ear panel 4 hours minimum continuous ot 20 0 c 15 hours minimum on stondby at 200 C Indicated by Battery Low lamp on front panel...

Page 13: ...ot Used 9 n Held at K Time Bose 10 Logic 1 L y Information 11 M See Table 2 12 Ro N Not Used 13 Hold Reset P Not Used 14 PrescaJe R Not Used NOTES 1 2 9915 Vol 2 External Hald Input If when used with...

Page 14: ...Ieve Is are appl ied to the CD I Chi n the ipstrument TABLE 2 Time Base Selection C0 1 Code Gate Time seconds x y z 0 1 01 1 0 1 0 1 0 0 1 1 1 0 10 Fu neti on Log i c Output The 9915 is 0 si ngl e fu...

Page 15: ...additional synchronising pulse Ro determines the first state lOo digit Accessories are available to give data output in parallel form for printers etc or IEC ASCII bus compatible formaL AS Fig Al not...

Page 16: ...fJJ9 PJ lJ I C1 9 J hLq tt I N h f www g0rsq co uk...

Page 17: ...nput AI is 0 500channel covering the range 40 MHz to 520 MHz prescaled by ten and with a g c automatic overload protection and overload indicator The front panel symbol advises the user to consult the...

Page 18: ...e via an adjacent BNC socket When external standard is connected the instrument automatically changes to external standard operation AC tJlAINS SUPPLY 1 11 The instrument operates from a c suppl ies b...

Page 19: ...Connect the external signal to the appropriate input socket IAI or IBI The damage overload input levels are Input A I 35V r m s overload protection above 5V r m s Input IB 250V r m s up to 10 kHz 50V...

Page 20: ...put signal 1 Set the NORMAL BURST switch to BURST the SENSITIVITY control to the 10 mV setting Select required Input channel and operate 2 Briefly press the CHECK OPERAlE RESET swi tch to RESET The di...

Page 21: ...automatically overrides the LF facility 3 When no input signal is applied it is normal for the instrument to show a count of 1 or 2 2 8 l Connect the a c mai ns supply 2 Set the rear panel swi tch to...

Page 22: ...i Ilator ii With BATT selected the battery economy operation will be available iii If CHARGE s selected the instrument will not charge the battedes Power OFF In the OFF position the charging and opera...

Page 23: ...clockwise t the switched position This switch selects the operational input channe NORMA Lprovides conti nuous measuremen with updated display BURST provides a single shot reading from either an inter...

Page 24: ...n opera Hon See page 2 4 The input BNC socket for the external frequency standard A 1 MHz reference signal derived from the frequency standard in use js ovaiIable at this BNC socket Provides indicotio...

Page 25: ...tions are carried out in the integrated circuit IC6 which achieves large scale integration using the collector diffusion isolation principle For convenience IC6 will often be referred to in the handbo...

Page 26: ...ut di splay The incomi ng signal then automatico Ily resets the counter and aIlows a sin9 Ie measurement to be mode and he Id f Light emitting diode LED indicators ore provided os follows i Overflow S...

Page 27: ...e noted that part of the system is in the CDI Chip 3 5 In the CDJ Ch ip the data stores feed in paralle I into 0 common b c d four I i ne output The store outputs are enabled in turn for approximately...

Page 28: ...Table 2 in the Technical Speci fi cation Resistor Arrays 3 9 Many of the integrated circuits are lopen collector types For these Cs discrete pull upl resistors are provided in the circuit These resist...

Page 29: ...hin the gate time or up to 100 ps after gate e losu re To inHia te a new eyeIe of mea urement the external hol d must go I high 1 for not Iess than 200 lJs External Reset 3 12 Externa I rese t is aehi...

Page 30: ...reference such as IC10a 3 which indicates pin 3 an that particular gate The logic symbols used in the circuits are those found in most manufacturers IC data sheets to which reference should be made i...

Page 31: ...D21 D22 with capad tor C45 3 The operational amplifier IC29 4 Transistor Q33 which drives the front panel Overload indicator 4 8 The input signal is fed via C45 to the detector D21 D22 and the rectifi...

Page 32: ...e at approximately DV As the signa amplitude increases the voltage at the cathode of D29 and also at IC27b 7 will become increasingly negative When the voltage at IC27bj7 is equal to or more negative...

Page 33: ...ch 151 which is port of the Display Assembly This switch connects the 5V and 5V rails to the appropriate amplifier circuit and also to the IF Multiplier Option The switch also controls transistor Q7 i...

Page 34: ...umed that switch S50 is in the OPERATE position except for the CHECK 1 MHz signal routei ng TABLE 3 Signal Gat ing Paths Selected Signal IC9a Input Signal Poth Logi c Source A IC90 4 IC9b 12 i A amp e...

Page 35: ...r reset on a transition from J 1 t IQ Manual eset 4 25 To 0 tain manual reset the switc 550 is pressed to RESET and released Reset occurs at the momen of release When th switch is pressed an earth log...

Page 36: ...lC17c are also at 1 IC17c ll receives a 1 via IC17a from the detector Q21 refer to para 4 35 and IC17c 9 is held at about 2 5V by the junction of R95 lOk and R38 4 32 After selecting BURST mode the o...

Page 37: ...data is fed from 1 6 on pins 15 to 18 this 4 way output being fed from a parallel to serial multiplex system within the COl Chip to the 7 segment decoder 1 on the Display Assembly 4 39 In the mul tipl...

Page 38: ...10kHz digit select If for example the 103 digit line is enabled IC25 4 a 10 is applied to IC230 1 thus 01 lowi ng the common output from IC23 to rise to 11 which turns on 023 during the 103 enable pe...

Page 39: ...5V supply is provided by the discrete diode bridge Dl7 D20 with fuse protection on the negative roil at FSl this fuse must be a normal quick action type 5V 5wi tch i ng 4 54 The 5V supply to the inst...

Page 40: ...2 4 59 Fi g 4 2 below shows the basic connedions to the nput of comparator IC12b OV 5 V FROM COLLECTOR Q 50 y 6 aK RBI 6 8K OUTPUT TO 029 ICI2b COMPARATOR l R80 R82 5V RAIL 5V Stabilizer Fig 4 2 4 60...

Page 41: ...l 050 C I off Thi OOoge M opercre wirh itll no or P 9 lUpllIy bur it rpcoe i bottery 4 63 lloneri il fitted tricl l dwwged _ i tn o lenI i ope i frcwn he moi ply fer dIorgi ood balt is COMe led bei vl...

Page 42: ...stabi Iized SV rai I at the collector of 050 The same SV supply turns on 027 which illuminates LP3 Battery Powered Operation 4 66 When switch 52 is set to the BATTERY position the contacts 52c and S2...

Page 43: ...few minutes of bottery life are remaining and re charging is essential Over Discharge Protection D14 4 71 The Battery Low indi cator informs the user that the batteries are in need of re charging If...

Page 44: ...ernal Standard Input 4 78 A 1 MHz external reference can be fed in via the rear panel BNC socket to the buffer amp Iifier 09 on the main p c b thence to the CD I ChiP at IC6 20 Whe n th is signa lis c...

Page 45: ...illator output at IC2 4 is fed via Q3 to 0 divide by 100 chain le3 and IC4 The divided signal is fed back via Q2 to pin 3 of IC2 where it is compared in phase with the original signal on pin 14 This p...

Page 46: ...r 1171 r 1 Racal Instruments Limited Duke Street Windsor Berks England wc1 J c1 Jt I Prepared by Central Handbooks Department Racal Group Services Limited The Electronics Group Printed in England Ref...

Page 47: ...red range 10 Hz to 530 MHz Output from 5 mV Racal 9061 r m s to lV r m s into 500 9062 combination NOTE LF Signal Generator must 9063 have signal to noise 9064 ratio better than 40 dB 5 Mi 1I i voltme...

Page 48: ...can now be lifted and the cover withdrawn ou v ards and rearwards 6 To replace the covers reverse the above procedure TRANSFORMER VOLTAGE SELECTION 5 2 The inshument will normally be dispatched with...

Page 49: ...212 239V 0 0 0 0 I I IB8V TO 265V I I L __ J UIlK L 0 10 112 115 0 100 12 12 223 25lV 0 0 9 9 0 0 I I I L __ J N LINK l lOO 112 m 0 1C 111 115 235 265V 0 0 9 9 0 0 I I ___ J llNK l 106 119V 11lH32V N...

Page 50: ...ceding paragraphs 2 Set the rear panel switch to MAINS 3 With power supply connected switch POWER to ON 4 Using the mul time er Page 5 1 Table 1 item 1 check the d c vo lages at the following points o...

Page 51: ...ry power veri fy that the BATTERY LOW indicator i not illuminated Illumination indicates that batteries need chorgi ng 4 Set the fall OWl ng controls a INPUT switch to lA b CHECK OPERATE RESET switch...

Page 52: ...click position and verify a display of 000000 01 6 counts in all positions of the GATE TIME switch Check and ca Iibration procedures For the internal frequency standard are given in poras 5 17 to 5 1...

Page 53: ...equency r m s 10s 10 Hz 10 mV ls 1 kHz 10 mV O 1s 10 MHz 10 mV 9915 Vol 2 5 6 7 8 9 10 With a 10 MHz input increase the signal level to greater than 500 mY Turn the SEN SITIVITY control clockwise and...

Page 54: ...reduce input level to 7 mV and adjust R125 on the main p c b clockwise until counting is correct Refer to Fig 3 at back of book for component location 4 Select the 105 gafe time and check that the OV...

Page 55: ...st Equipment 1 VHF Signal Generator Page 5 1 TabJe4 item 4 2 Mu Itimeter Page 5 1 Table 4 item 1 5 12 Procedure 1 Set the controls os in para 5 10 1 2 Apply a frequency of 40 MHz to Channel lA input 3...

Page 56: ...f approximately one minute BATTERY CHARGING CHECKS 5 15 The chargjn9 current with the optionaI battery pack fi tted wi vary considerabIy durin9 the 4 hour charge period However the nominoI values duri...

Page 57: ...esistor R73 located just in front of the mains transformer 5 Measure the voltage across the resistor 6 Set the BATTERY CHARGE MAINS switch to MAINS for trickle charge 7 Repeat operation 5 Battery I BI...

Page 58: ...ure 1 Allow a suitable warm up period not less than one hour for a temperature controlled osci lator 9915 Vol 2 2 3 4 5 6 Set the oscilloscope time base to 1 Js cm Connect the 1MHz externa Istandard t...

Page 59: ...lly withdrawn os far os the wi ri ng perm its Toke care not to di stort the pi ns of the edge connector on the main p c b when wi thdrawi ng ond re fi tti ng 6 To detach the Display Assembly i Remove...

Page 60: ...h secure the p c b to the main frame and 51 ide out the p e b towards the rear 5 22 Replacement of Main PCB When re fitting a main p e b a new c 1pacitor retaining strap should be fitted as follows 99...

Page 61: ...ce of the reor panel 01 ign the fi xi ng holes in the top of the unit wi th the rear pane I holes and make secure with two M3 6 mm screws The screws removed wi th the block plate con be used 4 Solder...

Page 62: ...readed hoIes 0 n the inner fa ce of the ri gh t ha nd side member 3 Place the mounting bracket against the inner face of the left hand side member wi th the large hole in the bracket located over the...

Page 63: ...wo screws to the right hand side panel of the instrument towards the rear 1 Remove the top cover para 5 1 2 If the optional frequency standard unit is fitted it must be detached by removing the two re...

Page 64: ...sted to include the following information a Instrument type and serial number b The type reference of the Assembly in which the particular item is located for example 19 0834 c The Part number and cir...

Page 65: ...Inc l oj l P o 1 11 I I I ______ J 01 I I r Il 01 I I 01 0 1 6 I I I L __ A t I I Vib AV CONI EcrOR I ______ F rr I Ot l TRoI CK I SIDE OF B lARO I I l 1 I I I I ICI LP 2 o ILI I _ J J DJ I Compo ent...

Page 66: ...Rl S3 R2 R3 Cl 22 4128 26 5004 23 4081 23 4081 23 5139 7 Segment Decoder Driver 74247 Indi cators 7 Segment Display LE D i ndi cator red 5082 4484 Switches Switch slide INPUT Switch slide MODE Connec...

Page 67: ...2 RI 100 C n l p l7p I 2 J 0 0 Cl 0 c J RI R2 0 R3 C 1 t R 0 C i c XLI 119 08H Circuit And Layout 5MHz Oscillator pea 19 0834 Fig 2 www g0rsq co uk...

Page 68: ...20 2102 Carbon Film 1 5 lk R2 4 20 2103 Carbon Fi Im 1 5 10k f 20 2153 Carbon Film 5 15k R3 4 Capacitors V F 21 1616 Ceramic 12 20 lOOn Cl 21 2621 Silver Mica 125 5 27p C5 21 2631 Silver Mica 125 5 3...

Page 69: ...550 23 4064 Switch Toggle POWER S51 23 3030 Sockets BNC Inputs A and B For other items refer to Display Assembly components list 19 0710 REAR PANEL ASSEMBLY COMPONENTS 11 1092 T50 DSO FS50 FSSO 17 40...

Page 70: ...0 2181 Coroon Film I 5 180 R27 35 36 136 21 1039 Tonlalum 16 20 22ft C6 2O 21B2 arbon Film 5 1 8k Rl40 21 1512 Ceramic SOD 10 22p Cl 16 20 2184 Calban film 1 5 lOOk Rll0 21 1520 Ceramic 10 lOOp C9 68...

Page 71: ...122 RI44 wos not filled Pin 23 of main p c b was connected to OV R145 was not fi lled 22 6101 22 6112 22 6113 22 6079 22 6123 22 6057 22 6009 22 6079 2N2369 IC9 IC15 IC17 IC1 16 IC29 IC2 IC19 IC18 IC5...

Page 72: ...2 Carbon Film 1 5 5 6k R12 4 20 2564 Carbon Film 1 5 560k R3 4 Capacitors V F 21 1002 Tantalum 20 20 101 1 C5 6 21 1029 Tantalum 35 20 1 5fJ Cl 2 21 1038 Tantalum 6 3 20 47fJ C3 21 1516 Ceramic 500 10...

Page 73: ...Rf 8_ r R g a 3 4 ICl8 CJ1 1151 11SO liS M e I 51 2 16 27 28 T _ C 1I 9 I Component Layout Main PC B Assembly 19 0708 I Fig 3 www g0rsq co uk...

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Page 77: ...SECTION 4 APPENDICES AND CHANGE INFORMATION www g0rsq co uk...

Page 78: ...NG EQUIPMENT WHICH PROVIDES HOLD SIGNALS 3 Frequency Meters Normal Use 4 Universal Counter Timers UCT s Basic Hold Requirements 5 UCT s Using Print Hold Mode 5 UCT s Using Hold Reset Mode 5 SPECIAL AP...

Page 79: ...e for control purposes 2 Print Command a signal output by the interface to indicate that new measurement information is available 3 Print Hold input An input which allows the user s Hold Signal to pre...

Page 80: ...UREMENT NEW MEASUREMENT DATA GATE TIME L E D_ O T _ I I I 1 I I l lm m l 1 1 L I r 1 1 I 1 OLD MEASUREMENT DATA I I x I I I I r 4DATA NOT VALID I I 1 1 _ _ I 0 8 1 5 rns DATA UPDATE PRINT COMMAND OUTP...

Page 81: ...longer than the gate time check the following pin conditions on the 50 way connector Pin No 19 24 49 Required Connection Must be either open circuit or connected to ay Latched Operation 9 The display...

Page 82: ...d whilst a Hold is applied the counter continues its normal measurement sequence i e free run l This has the advantage that the next Print Command will be given at the end of the gate time immediately...

Page 83: ...nnector are as follows Pin No Pin 19 Pin 49 Pin 24 Requi red Connection Connected to Pin 50 or to 5V via 1800 Connected to the Hold si gnal source To be open ci rcuit or connected to 01 UCT s Using Ho...

Page 84: ...he reading at the end of the next gate time will be incorrect Alternatively if the correction process takes more than one gate time the end of gate time immediately following the process will also giv...

Page 85: ...reset For cases where the correction time is short less than the Print Command pulse width this may be implemented by linking the Print Command output pin 48 to the Hold Reset input pin 24 and by app...

Page 86: ...cted Not Connected Not Connected HOLD RESET See NOTE 1 Ro l 2 3 4 5 6 7 8 9 10 1l 12 13 14 NOTE 1 In option 01 units with serial numbers after 1389 pin 14 of the flying lead connection is connected wi...

Page 87: ...T 35 2 10 5 DIGIT 1l 4 36 4 12 8 37 8 13 38 14 2 10 6 DIGIT 39 2 10 7 DIGIT 15 4 40 4 16 8 4l 8 17 OVERFLOW 42 4 10 8 DIGIT 18 10 8 DIGIT 43 See table 1 NOTE 1 19 HOLD CONTROL P 44 8 10 8 DIGIT 20 2 1...

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