Model 418A Universal Coincidence Operating and Service Manual
Contents
1. ATTENTION Refer to Manual DANGER High Voltage Please read all safety instructions carefully and make sure you understand them fully before attempting to use this product vi SAFETY WARNINGS AND CLEANING INSTRUCTIONS DANGER Opening the cover of this instrument is likely to expose dangerous voltages Disconnect the instrument from all voltage sources while it is being opened WARNING Using this instrument in a manner not specified by the manufacturer may impair the protection provided by the instrument Cleaning Instructions To clean the instrument exterior Unplug the instrument from the ac power supply Remove loose dust on the outside of the instrument with a lint free cloth e Remove remaining dirt with a lint free cloth dampened in a general purpose detergent and water solution Do not use abrasive cleaners CAUTION To prevent moisture inside of the instrument during external cleaning use only enough liquid to dampen the cloth or applicator e Allow the instrument to dry completely before reconnecting it to the power source ORTEC MODEL 418A UNIVERSAL COINCIDENCE 1 DESCRIPTION 1 1 GENERAL The ORTEC 418A is a coincidence unit with five inputs Each input has a three position switch associated with it to select the COINCIDENCE ANTICOINCIDENCE or OFF mode The resolving time of Input A is controlled by a front panel potentiometer and is continuously variable from 100 ns to2. CR29 is determined by the amount of reverse current flowing in CR29 The quiescent current flowing in CR29 is controlled by the COINCIDENCE REQUIREMENTS switch and Q26 If CR29 is triggered to its high state a one shot Q27 Q29 is triggered which produces a 5 V 500 ns wide pulse This pulse is passed through two emitter followers to the output connectors 5 1 INPUT A INPUT A is fed to a current switch QI and Q3 through a diode limiter consisting of CR1 CR2 R1 R2 R3 and R4 The limiting action is accomplished when a positive voltage large enough to switch the constant current that normally flows through CR1 and RI to the limiter load R3 and R4 is applied to the input This causes the QI base voltage to exceed ground potential and turn QI on Emitter follower Q2 drives the base of Q6 negative through the timing capacitor C2 with the pulse from the collector of AI The resolving time of INPUT A 7 is determined by the length of time that Q6 is off The constant current generator Q4 controls the off time of Q6 7 by discharging capacitor C2 back from its negative value toward ground When the voltage at the base of Q6 exceeds ground potential Q6 is turned on again Q8 converts the voltage pulse at Q6 collector to a current pulse to drive the coincidence stage Q5 is used as a feedback element to ensure that the pulse from the input current switch QI collector has a minimum duration of 7 regardless of the input pulse wi
3. are 5 V in amplitude and 500 ns wide The output pulse width can be altered as desired by changing capacitor C9 The amplitude can be increased by increasing the value of R75 TEST POINT An oscilloscope test point is provided for monitoring the output signals The test point has a 4700 resistor connecting it to the associated BNC output connector on the front panel 4 3 INITIAL TESTING AND OBSERVATION OF PULSE WAVEFORMS Refer to Section 6 for information on testing performance and observing waveforms 4 4 TYPICAL OPERATING CONSIDERATIONS The coincidence circuit is an overlap type or it can be described as an AND circuit The 2T resolving time of INPUT A is determined by the INPUT A RESOLVING TIME control See timing diagrams in Figs 4 1 through 4 5 If the coincidence requirements are met by the input pulses two standard output pulses 500 ns wide and 5 V in amplitude are produced regardless of the overlap time of the coincident pulses The width of the output pulses may be changed by changing the value of C9 Careful attention should be given the 418A front panel controls when using it The input control toggle switches determine the routing of each input pulse The COINCIDENCE REQUIREMENTS switch determines the number of coincident pulses required to yield an output pulse This means that the number of input control switches in the COINCIDENCE position must be equal to or greater than the number selected by the COINCIDENC
4. pass a stringent set of quality control tests designed to expose any flaws in materials or workmanship Permanent records of these tests are maintained for use in warranty repair and as a source of statistical information for design improvements Repair Service If it becomes necessary to return this instrument for repair it is essential that Customer Services be contacted in advance of its return so that a Return Authorization Number can be assigned to the unit Also ORTEC must be informed either in writing by telephone 865 482 4411 or by facsimile transmission 865 483 2133 of the nature of the fault of the instrument being returned and of the model serial and revision Rev on rear panel numbers Failure to do so may cause unnecessary delays in getting the unit repaired The ORTEC standard procedure requires that instruments returned for repair pass the same quality control tests that are used for new production instruments Instruments that are returned should be packed so that they will withstand normal transit handling and must be shipped PREPAID via Air Parcel Post or United Parcel Service to the designated ORTEC repair center The address label and the package should include the Return Authorization Number assigned Instruments being returned that are damaged in transit due to inadequate packing will be repaired at the sender s expense and it will be the sender s responsibility to make claim with the shipper Instruments not in warra
5. 2 Us The remaining four inputs are dc coupled and their resolving times are determined by their input pulse widths By means of a front panel switch 1 2 3 4 or 5 coincident pulses may be required for an output and all five inputs are used in the coincident mode an output pulse will be obtained when a coincident occurs between any two inputs Input A is particularly useful for anticoincidence and coincidence strobe operations because of its variable resolving time e g this input can be used in the anticoincidence mode to block two 500 ns wide input pulses without additional external pulse shaping equipment Two positive output pulses are provided on BNC connectors one front panel and one rear panel These pulses are normally 500 ns wide but their width can be altered as desired by changing a capacitor 1 2 BASIC FUNCTION The 418A employs an overlap type of coincidence circuit Each input pulse is regenerated into a current pulse which has a fast rise and fall time These current pulses are fed into an AND circuit which produces an output when an overlap occurs The width of the current pulse from Input A is controlled by a front panel potentiometer and can be varied from 100 ns to 2 Us The current pulses from the remaining inputs are the same width as their associated input pulses at the 1 8 V level Since these inputs are dc coupled their current pulses can be made infinitely long by the application of a dc voltage to th
6. A test point Increase the 416B DELAY control until the 418A output pulse disappears 7 Check the 416A and 416B outputs with the oscilloscope again The leading edges of these two pulses should be 2 Us apart 8 Repeat steps 4 through 7 except for the following changes Set INPUT A RESOLVING TIME Control to Minimum Step 7 The leading edges of the two pulses from the 416A and 416B should be less than 100 ns apart 9 Place 418A input control switches to OFF INPUT A RESOLVING TIME to 0 1 Us and COINCIDENCE REQUIREMENTS to 1 10 Sequentially place each INPUT CONTROL switch to COINCIDENCE and then to OFF An output pulse should appear on the oscilloscope each time a switch is placed to the COINCIDENCE position and should disappear when the switch is returned to OFF position II Place the COINCIDENCE REQUIREMENTS switch to 2 Place switch A to the COINCIDENCE position and all others to the OFF position An output pulse should not be present Place switch B to the COINCIDENCE position and an output pulse should appear 12 Place the COINCIDENCE REQUIREMENTS switch to 3 and the output pulse should disappear Place switch C to the COINCIDENCE position and an output pulse should appear 13 Place the COINCIDENCE REQUIREMENTS switch to 4 and the output pulse should disappear Place switch D to the COINCIDENCE position and an output pulse should appear 14 Place the COINCIDENCE REQUIREMENTS switch to 5 and the output pulse should
7. CIDENCE REQUIREMENTS switch If the 418A is still suspected of malfunctioning it is essential to verify such malfunctioning in terms of simple pulse generator impulse at the input and output In consideration of this the 418A must be disconnected from its position in the system and routine diagnostic analysis performed with a test pulse generator and oscilloscope It is imperative that testing not be performed with a source and detector until the logic inputs to the coincidence unit perform satisfactorily with the test pulse generator The testing instructions in Section 6 1 Of this manual and the circuit description in Section 5 should provide assistance in locating the region of trouble and remedying the malfunctioning The guide plate and shield cover can be completely removed from the module to enable oscilloscope and voltmeter observations with a minimal chance of accidentally short circuiting portions of etched board The 418A may be returned to ORTEC for repair service at nominal cost Our standardized procedure requires that each repaired instrument receive the same extensive quality control tests that a new instrument receives 6 3 TABULATED TEST POINT VOLTAGES ON ETCHED BOARD The following dc voltages are intended to indicate the typical voltages measured on the etched circuit board The voltages given here should not be considered as absolute values but should be used as an aid in troubleshooting All voltages were me
8. E REQUIREMENTS switch see Fig 4 5 _ INPUT B COINCIDENCE MODE EN is At INPUT C COINCIDENCE MODE En Llen OUTPUT Fig 4 1 Coincidence Requirements When Switch Setting Is 2 A E INPUT A COINCIDENCE MODE Sf A INPUT A INTERNAL REGENERATED CURRENT PULSE E e NEE INPUT D COINCIDENCE MODE ded Lo OUTPUT Fig 4 2 Coincidence Requirements When Switch Setting Is 2 EEN es a INPUT B ANTI COINCIDENCE MODE ls E INPUT C COINCIDENCE MODE gt J ek INPUT D COINCIDENCE MODE Ue INPUT E COINCIDENCE MODE mannaaa OUTPUT Fig 4 3 Coincidence Requirements When Switch Setting Is 3 AO APA INPUT B ANTI COINCIDENCE MODE er ie eed EA INPUT C COINCIDENCE MODE ll reed INPUT D COINCIDENCE MODE e eee OUTPUT Fig 4 4 Coincidence Requirements When Switch Setting Is 2 J Peai INPUT B COINCIDENCE MODE a deea a INPUT C COINCIDENCE MODE A A INPUT D COINCIDENCE MODE OUTPUT 200485 Fig 4 5 Coincidence Requirements When Switch Setting Is 4 5 CIRCUIT DESCRIPTION The 418A has five dc coupled inputs which may be used in the coincidence or anticoincidence mode Each input is protected by a diode limiter INPUT A has a variable resolving time while INPUTS B through E have a resolving time determined by their input pulse widths The input controls route the signals from these inputs to the coincidence CR29 or anticoincidence Q25 stage The number of coincident pulses required to trigger the coincidence stage tunnel diode
9. ING INSTRUCTIONS 4 1 FRONT PANEL CONTROLS INPUT A RESOLVING TIME CONTROL Each input pulse is regenerated into a current pulse with fast rise and fall times The width of the current pulse from INPUT A is continuously variable from 100 ns to 2 4 The current pulses from the remaining inputs are the same width of these current pulses at the 1 8 V level The width of these current pulses determines the resolving time of the unit INPUT A RESOLVING TIME control is especially useful when INPUT A is used in the anticoincidence mode e g this input can be used to block two 500 ns wide pulses without additional external pulse shaping equipment COINCIDENCE REQUIREMENTS The position of this switch determines the number of coincidence pulses required to produce an output pulse e g if this switch is in the 2 position and all input control switches are in the COINCIDENCE position an output pulse will be produced when any two input pulses are in coincidence In order to obtain an output pulse the number of input control switches in the COINCIDENCE position must always be equal to or greater than the number of selected by the COINCIDENCE REQUIREMENTS switch INPUT CONTROLS Each of the five three position locking toggle switches determines the routing of the signal applied to its associated input connector The three positions of each switch and their function are 1 COINCIDENCE Input signal is routed to the coincidence portion o
10. NTROLS eeen 3 4 2 CONNECTOR DATA 51 sooo a wees abe geteelde t aud eg bey eae eee G bee bee ea 3 4 3 INITIAL TESTING AND OBSERVATION OF PULSE WAVEFORMS 3 4 4 TYPICAL OPERATING CONSIDERATIONS eeen 3 5 CIRCUIT DESCRIPTION occ 4 Sale INPUTEA coser gingi pineke ooe sloes ginge ulmele alea vee eeste giore glee gle pie 5 5 2 INPUES B OD And Bme re each laa Ree ec ack ase a lates Reseda cede tease totes 5 6 CALIBRATION AND MAINTENANCE een 6 6 1 TESTING PERFORMANCE OF SLOW COINCIDENCE 0 000000 ee eee eee 6 6 2 SUGGESTIONS FOR TROUBLESHOOTING ee 8 6 3 TABULATED TEST POINT VOLTAGES ON ETCHED BOARD 0 8 UNIVERSAL COMCIDENMCE Ei EHE Det BDE ACE PCH AT SAFETY INSTRUCTIONS AND SYMBOLS This manual contains up to three levels of safety instructions that must be observed in order to avoid personal injury and or damage to equipment or other property These are DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction is not observed WARNING Indicates a hazard that could result in bodily harm if the safety instruction is not observed CAUTION Indicates a hazard that could result in property damage if the safety instruction is not observed Please read all safety instructions carefully and make sure you understand them fully before attempting to use this product In addition the following symbol may appear on the product
11. Printed in U S A Model 418A Universal Coincidence Operating and Service Manual ORTEC Part No 733170 Manual Revision B 1202 Advanced Measurement Technology Inc a k a ORTEC a subsidiary of AMETEK Inc WARRANTY ORTEC warrants that the items will be delivered free from defects in material or workmanship ORTEC makes no other warranties express or implied and specifically NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ORTEC s exclusive liability is limited to repairing or replacing at ORTEC s option items found by ORTEC to be defective in workmanship or materials within one year from the date of delivery ORTEC s liability on any claim of any kind including negligence loss or damages arising out of connected with or from the performance or breach thereof or from the manufacture sale delivery resale repair or use of any item or services covered by this agreement or purchase order shall in no case exceed the price allocable to the item or service furnished or any part thereof that gives rise to the claim In the event ORTEC fails to manufacture or deliver items called for in this agreement or purchase order ORTEC s exclusive liability and buyer s exclusive remedy shall be release of the buyer from the obligation to pay the purchase price In no event shall ORTEC be liable for special or consequential damages Quality Control Before being approved for shipment each ORTEC instrument must
12. REMENTS Selectable by front panel switch i e 1 2 3 4 or 5 coincident pulses may be required to yield an output For example if the COINCIDENCE REQUIREMENTS switch is set to 3 and all five INPUT CONTROL switches are set to COINCIDENCE an output will be obtained when a coincidence occurs between any three inputs TEMPERATURE STABILITY Change in INPUT A resolving time T is less than 0 1 C change in INPUTS B C D and E resolving time T is less than 0 5 C T 500 ns OPERATING TEMPERATURE 0 to 50 C CONTROLS INPUTS Each input has a three position locking toggle switch associated with it which permits any input to be used in the COINCIDENCE ANTICOINCIDENCE or OFF mode When the OFF mode is selected the respective input is disabled INPUTS POLARITY Positive 2 V minimum 30 V maximum PULSE WIDTH 50 ns to dc IMPEDANCE gt 1 5k0 dc coupled OUTPUTS Two each dc coupled positive 5 V 500 ns wide impedance lt 10Q MECHANICAL AND ELECTRICAL MECHANICAL One module wide and designed to meet the recommended interchangeability standards set forth in DOE Report TID 20893 Rev 1 35 in Wide 8 714 in High and 9 75 in Long POWER REQUIREMENTS 24 V 105 mA 12 V 50 mA 24 V 90 mA 12 V 30 mA 3 INSTALLATION 3 1 GENERAL The 418A used in conjunction with a 4001A 4002A Bin and Power Supply is intended for rack mounting therefore any vacuum tube equipment operating in the same rack mu
13. asured from ground with a DVM having an input impedance of 10 MQ or greater Voltages are dc values with no input pulses Set INPUT A RESOLVING TIME Control to 0 1 Us min Set COINCIDENCE REQUIREMENTS switch to 1 Test Point _ Voltage Test Point _ Voltage Qic 11 5 Q18b 1 8 Q4b 14 5 Q18c 10 8 Q6b 0 7 Q21b 0 Q6c 10 0 Q22b 1 8 Q7c 11 9 Q22c 10 8 Q9b 0 Q25b 0 6 Q10b 1 8 Q26b 2 9 Q10c 10 8 Q26c 0 Q13b 0 Q27b 12 0 Q14b 1 8 Q29b 11 7 Q14c 10 8 Q29c 0 3 Q17b 0 BIN MODULE CONNECTOR PIN ASSIGNMENTS FOR STANDARD NUCLEAR INSTRUMENT MODULES PER DOE ER 0457T 1 3 volts 2 3 volts 3 Spare Bus 4 Reserved Bus 5 Coaxial 6 Coaxial 7 Coaxial 8 200 volts dc 9 Spare 10 6 volts 11 6 volts 12 Reserved Bus 13 Spare 14 Spare 15 Reserved 16 12 volts 17 12 volts 18 Spare Bus 19 Reserved Bus 20 Spare 21 Spare Reserved 28 29 30 31 32 33 34 36 37 38 39 41 42 Reserved Reserved Reserved Spare Spare 24 volts 24 volts Spare Bus Spare Spare 117 volts ac Hot Power Return Ground Reset Scaler Gate Reset Auxiliary Coaxial Coaxial Coaxial 117 volts ac Neut High Quality Ground Ground Guide Pin Pins marked are installed and wired in ORTEC 4001 A and 4001C Modular System Bins 10
14. disappear Place switch E to the COINCIDENCE position and an output pulse should appear 15 Reduce the 416A and 416B output pulses to 2 0 V and ensure that a pulse still appears at the 418A output Reset the 416A and 416B output pulses to 5 V 16 Load both 418A outputs with 100Q The 418A output pulses should be a minimum of 5 V in amplitude and 500 ns wide 17 Set instrument controls as follows 416A DELAY RANGE 1 0 11 DELAY 400 WIDTH 4 us AMPLITUDE 5V 416B DELAY RANGE 1 0 11 DELAY 500 WIDTH 0 4 us AMPLITUDE 5V 418A INPUT A RESOLVING TIME CONTROL 2458 COINCIDENCE REQUIREMENTS 1 INPUT CONTROLS A and D OFF B C and E COINCIDENCE 18 Monitor the 418A output with the oscilloscope An output pulse should be present Sequentially place switches A and D to the ANTICOINCIDENCE mode and ensure that the output pulse disappears 19 Change the instrument controls as follows 416A DELAY 500 WIDTH 0 4 us 416B DELAY 400 WIDTH 4 us 418A INPUT A RESOLVING TIME Control 0 1 us INPUT CONTROLS A and D COINCIDENCE B C andE OFF 20 Monitor the 418A Output with the oscilloscope Ensure that the 418A output pulse disappears as switches B C and E are sequentially switched to the ANTICOINCIDENCE position 6 2 SUGGESTIONS FOR TROUBLESHOOTING Recheck front panel control settings Ensure that the number of INPUT CONTROL switches in the COINCIDENCE position is equal to or exceeds the number selected by the COIN
15. dth 5 2 INPUTS B C D and E These four inputs are identical so only INPUT B will be explained A diode limiter similar to that of INPUT A is provided This limiter is followed by a de Schmitt trigger circuit Q9 Q10 Q11 In the quiescent state the base of Q9 is at ground potential and the base of QIO is 1 8 V The Q10 base potential is maintained by the current from Q11 and R25 When a pulse is applied to the input and raises the base of Q9 above the potential at the base of QIO Q9 turns on and Q10 and Q111 turn off Due to the loss of the current supplied by Q11 the base of Q10 is now set at 0 9 V The circuit will be reset to its quiescent state when the input voltage drops below 0 9 V The hysteresis and threshold of the circuit can be altered by changing the value of R22 and R25 Q12 converts the voltage pulse at the collector of Q10 to a current pulse The current pulse from each input circuit is connected to a three position toggle switch input controls which routes the pulse to the coincidence stage ground OUT position or the anticoincidence stage The anticoincidence stage is composed of Q25 which is biased off in the quiescent condition An anticoincidence pulse saturates Q25 for the duration of the pulse When Q25 saturates it short circuits the coincidence line to ground thereby preventing coincidence signals from reaching the coincidence stage for the duration of the anticoincidence pulse The coincidenc
16. e input The routing of the individual current is controlled by front panel toggle switches They can be routed to the COINCIDENCE or AND circuit ground OFF position or the ANTICOINCIDENCE circuit The front panel COINCIDENCE REQUIREMENTS switch alters the AND circuits so that 1 2 3 4 or 5 coincident current pulses are required to produce an output therefore the number of INPUT CONTROL toggle switches in the COINCIDENCE position must be equal to or greater than the number selected by the COINCIDENCE REQUIREMENTS switch in order for the unit to produce an output A current pulse routed to the anticoincidence circuit blocks all pulses routed to the coincidence circuit for the duration of the anticoincidence pulse When the coincidence requirements are met a 500 ns wide output pulse is generated The width of this pulse can be changed as desired by changing the value of capacitor C9 2 SPECIFICATIONS The 418A is housed in a Nuclear Standard Module It is one module wide and weighs 1 5 Ib It contains no internal power supply and must therefore obtain the necessary operating power from the Nuclear Standard Bin and Power Supply ORTEC 4001A 4002A All signals in and out of the module are on front panel BNC connectors and an additional output BNC is on the rear panel PERFORMANCE RESOLVING TIME T INPUT A 100 ns to 2 Us controlled by 20 turn potentiometer INPUTS B C D E Controlled by input pulse width COINCIDENCE REQUI
17. e stage is composed of CR29 and Q26 When tunnel diode CR29 is set to its high state by the coincidence current pulses the 418A produces an output pulse The number of coincident current pulses required to set CR29 to its high state is determined by its quiescent current The bias current in CR29 is equal to the collector current of Q26 This current is controlled by the Q26 emitter resistor which is selected by the COINCIDENCE REQUIREMENTS switch The voltage pulse produced when CR29 is set to its high state turns Q27 and Q29 off The period of time that Q29 stays off is equal to the output pulse width and is controlled by C9 and R74 If a different output pulse width is desired the value of C9 should be changed The pulse at the collector of Q29 is dc coupled to the output connectors through two emitter followers Q30 and Q31 In the quiescent condition the bases of these transistors are at zero volts and they do not conduct The amplitude of the output pulses is determined by the ratio of R72 and R75 R75 should be increased in value to increase the output pulse amplitude An output pulse amplitude of approximately 10 V can be obtained by removing R75 from the circuit 6 CALIBRATION AND MAINTENANCE 6 1 TESTING PERFORMANCE OF SLOW COINCIDENCE INTRODUCTION The following paragraphs are intended as aids in the installation and checkout of the 418A These instructions present information on front panel controls and waveforms at te
18. f the circuit 2 OUT Input signal is routed to ground therefore it does not affect the coincidence or anticoincidence portion of the circuit and is completely out of the system 3 ANTICOINCIDENCE Input signal is routed to the anticoincidence portion of the circuit and will block all coincidence signals for the duration of the anticoinicdence signal except for INPUT A for which the blocking time is a function of the front panel RESOLVING TIME control Any combination of switch positions may be used however an output pulse can be obtained only when the number of input controls in the COINCIDENCE positions is equal to or exceeds the number selected by the COINCIDENCE REQUIREMENTS switch 4 2 CONNECTOR DATA INPUT A is a front panel BNC connector dc coupled to the internal circuitry and has an impedance to ground greater than 1 5 kQ To minimize reflections when driving from a low impedance source into this connector a terminator equal to the characteristics impedance of the driving cable should be shunted to ground A positive 2 V signal with a minimum width of 50 ns is required to trigger the input circuit The resolving time of INPUT A can be varied from 100 ns to 24 by the INPUT A RESOLVING TIME control INPUTS B C D E Same as INPUT A except that the resolving time is set by the input pulse width OUTPUTS Two separate buffered dc coupled coincidence outputs are provided on BNC connectors The output pulses
19. nty should follow the same procedure and ORTEC will provide a quotation Damage in Transit Shipments should be examined immediately upon receipt for evidence of external or concealed damage The carrier making delivery should be notified immediately of any such damage since the carrier is normally liable for damage in shipment Packing materials waybills and other such documentation should be preserved in order to establish claims After such notification to the carrier please notify ORTEC of the circumstances so that assistance can be provided in making damage claims and in providing replacement equipment if necessary Copyright 2002 Advanced Measurement Technology Inc All rights reserved ORTEC is a registered trademark of Advanced Measurement Technology Inc All other trademarks used herein are the property of their respective owners CONTENTS WARRANT Neree ii SAFETY INSTRUCTIONS AND SYMBOLS eneen v SAFETY WARNINGS AND CLEANING INSTRUCTIONS oen vi 1 DESCRIPTION arica al 1 1 1 GENERAL i ath tt et ont nt te oe te ec ed dd aca SE 1 1 2 BASIGEUNGTION sa oe Satan ati ld detta detail dl A dont date daat etende 1 2 SPECIFICATIONS soa nan cg a geen gain aide dang EERE ES 1 3 INSTALLATION rekene A A A A ee 2 SH GENERAL dd at Kuti sh Kath ith Rati hare Rad dies 2 3 2 CONNECTION TO POWER een 2 3 3 LOGIC INPUTS TO THE COINCIDENCE UNIT en 2 4 OPERATING INSTRUCTIONS wan sist daten tial ciel ER te er EER tent 3 4 1 FRONT PANEL CO
20. st be sufficiently cooled with circulating air to prevent any localized heating of the all transistor circuitry used throughout the 418A The temperature of the equipment mounted in racks can easily exceed the recommended maximum of 120 F 50 C unless precautions are taken 3 2 CONNECTION TO POWER Because the 418A contains no internal power supply it must obtain operating power from the Nuclear Standard Bin and Power Supply such as ORTEC 4001A 4002A It is recommended that the bin power supply be turned off when modules are inserted or removed The ORTEC NIM modules are designed so that it is not possible to overload the NIM power supply with a full complement of modules in the bin Since however this may not be true when the bin contains modules other than those of ORTEC design power supply voltages should be checked after the modules are inserted ORTEC 4001A 4002A has test points on the power supply control panel to monitor the dc voltages 3 3 LOGIC INPUTS TO THE COINCIDENCE UNIT The input pulses to the 418A may come from any source of logic pulses The input impedance is approximately 20000 and some care must be given to ensure that reflections do not occur in the driving transmission cable Reflections can probably best be avoided by terminating the driving cable at the inputs with the characteristic impedance of the driving cable The amplitude and width of the input signals are specified in Section 2 2 4 OPERAT
21. st points and output connectors TEST EQUIPMENT The following or equivalent test equipment is needed ORTEC 419 or 480 Pulse Generator ORTEC 410 435A 440A 450 or 451 Amplifier Two ORTEC 416 Gate and Delay Generators Tektronix Model 580 Oscilloscope 1000 BNC terminators PRELIMINARY PROCEDURES 1 Visually check module for possible damage due to shipment 2 Connect ac power to nuclear standard bin ORTEC 4001A 4002A 3 Plug module into bin and check for proper mechanical alignment 4 Switch on ac power and check the dc power supply voltage at the test points on the 4001A Power Supply control panel COINCIDENCE TESTING 1 Connect the above test equipment as shown in Fig 6 1 The ORTEC 416 s will be referred to as 416A and 416B for clarity 2 Adjust the 419 and 410 for a 6 V output pulse from the 410 3 Set the 416A and 416B controls as follows DELAY RANGE switch Lot DELAY control 500 WIDTH control Minimum AMPLITUDE control 4V EXT TRIG Fig 6 1 ORTEC 418A Test Circuit 4 Set the 418A controls as follows INPUT A RESOLVING TIME Control Maximum COINCIDENCE REQUIREMENTS Control 2 INPUT Controls A COIN B COIN Cc OFF D OFF E OFF 5 Monitor the 416A and 416B outputs with the oscilloscope Adjust the 416B DELAY control until the leading edges of the two pulses are in coincidence 6 Monitor the 416B and 418A outputs with the oscilloscope An output pulse should be present at the 418
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