Model 426 Linear Gate Operating and Service Manual
Contents
1. Norm Input pulse will be gated through to the output during a gate width interval following the leading edge of each Enable input pulse Pulse Inhibit Input pulses will be inhibited from passing through the output during a gate width interval following each Enable input pulse DC Inhibit Input pulses will be inhibited from passing through the output during intervals of pulses or dc level through the DC Inhibit Input connector on the rear panel 2 3 INPUTS Input Unipolar or bipolar with positive portion leading Rated range 0 2 to 10 V 12 V maximum Input impedance gt 5000Q BNC connector on front panel Enable or Inhibit Any positive input gt 2 V maximum input 20 V Enable impedance 10000 dc coupled Inhibit impedance 650Q dc coupled Front panel BNC connector for each DC Inhibit Rear panel BNC connector inhibits input pulses from passing through the output during intervals of pulses or dc levels impedance 6500 dc coupled 2 4 OUTPUT Rated output range 0 2 to 10 V positive 12 V maximum Output impedance 2Q short circuit protected BNC connector 2 5 ELECTRICAL AND MECHANICAL Power Requirements 24 V 30 mA 12 V 16 mA 24 V 49 mA 12 V 4 9 mA Weight Shipping 4 0 Ib 1 82 kg Weight Net 2 1 Ib 0 96 kg Dimensions Single width module 1 35 by 8 714 in per TID 20893 Rev 2 6 RELATED EQUIPMENT The input to the linear gate of the 426 can be from any of the linear circuitry i2. Measure the input and output of the 426 The input should not differ from the output by more than 80 mV 6 Adjust the 410 gain controls to give a 8 V pulse into the linear Input of the 426 The Linear Gate Output should be 8 0 4 V Load the 426 Output with 1000 The output pulse amplitude should not decrease more than 0 15 V 7 Adjust the 410 Linear Amplifier gain controls to give a 11 V pulse into the Input of the Linear Gate The Linear Gate Output should saturate at greater than 20 V 8 Remove the 427 Output from the linear Input on the 426 Rotate the Gate Width control over its entire range and measure the resultant gating period The minimum should be 0 3 usec or less and the maximum should be 4 usec or greater 5 2 ADJUSTMENT OF LINEAR GATING DURATION The linear gating period is continuously variable from approximately 0 3 usec to 4 usec The pulse width is controlled by capacitor C8 and resistors R34 and R35 To change the gating duration simply adjust the control R35 which is recess mounted on the front panel In the event that gating durations different from 0 3 to 4 Us are desirable the capacitor C8 may be replaced with a capacitor of different value to change the range of gating duration R35 will provide continuously adjustable pulse width within the new range 5 3 ADJUSTMENT OF LINEAR GATE PEDESTAL The Linear Gate has a trim potentiometer R11 to allow the pedestal on the Linear Gate Output to be r
3. being approved for shipment each ORTEC instrument must 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 t
4. ground Ground guide pin Pins marked are installed and wired in ORTEC s 4001A and 4001C Modular System Bins
5. 2 6 RELATED EQUIPMENT 3 1 CONNECTION TO POWER 0 20 00 ccc eens 3 2 INPUT SIGNAL CONNECTION TO LINEAR GATE 0 00000 e eee eee 3 3 LOGIC INPUT TO THE ENABLE INPUT 0 0 0 0 eee 3 4 LOGIC INPUTS TO THE DC INHIBIT INPUT 0 0 0 0 ranner 3 5 LINEAR OUTPUT SIGNAL CONNECTIONS AND TERMINATING IMPEDANCE CONSIDERATIONS ee NEEN eae CEE SEG EEE GE ET EGE ES EERE Sa Ra OPERATION sive ei See ek Oe Oe BEES Se ERE EE EEE BER E Hie Se EE ee ee ae DERE ee ee ES 4 1 FRONT PANEL CONTROLS nee EE EE EE EE EELER EE EELER EE EE EE EE ET 4 2 INITIAL TESTING AND OBSERVATION OF PULSE WAVEFORMS 4 3 CONNECTOR DATA 4 4 TYPICAL OPERATING CONSIDERATIONS 5 1 TESTING THE PERFORMANCE OF THE LINEAR GATE 5 2 ADJUSTMENT OF LINEAR GATING DURATION 5 3 ADJUSTMENT OF LINEAR GATE PEDESTAL 0 000 c eee eae 5 4 TABULATED TEST POINT VOLTAGES 0 0 ccc ees 5 5 SUGGESTIONS FOR TROUBLESHOOTING 5 6 FACTORY REPAIR 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 proper
6. Model 426 Linear Gate Operating and Service Manual This manual applies to instruments marked Rev 23 on rear panel Printed in U S A ORTEC Part No 733200 1202 Manual Revision B 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
7. adjustment that allows the Linear Gate to operate with no pedestal The series parallel transistor switch is activated by a transistor pair current switch This latter switch is activated by the gate control pulse which is generated with the application of an externally generated Enable pulse The output of the Linear Gate circuit is fed into a cascode emitter follower cable driver The ORTEC 426 has two operating modes normally blocks all input signals not accompanied by an Enable pulse and normally passes all signals unless accompanied by an Inhibit signal The Inhibit signal can be fed into the front panel Enable connector for Pulse Inhibit operation or into the DC Inhibit Input connector for de or continuous inhibit operation 2 SPECIFICATIONS 2 1 PERFORMANCE Gain Unity Integral Nonlinearity lt 0 15 from 0 2 to 10 V Pulse Feedthrough lt 10 mV with a 10 V input pulse Temperature Stability lt 0 015 C 0 to 50 C Counting Rate The gain shift of a 4 V reference pulse is lt 0 25 with the application of an additional count rate of 65 000 counts sec of 6 0 V random pulses 2 2 CONTROLS Gate Width Continuously variable from 0 3 to 4 Us Output Pedestal Adjustable to lt 1 mV Pulse Inhibit Norm DC Inhibit 3 position mode switch that permits selection of the function of any pulse or dc level furnished through the Enable input connector which is on the front panel or the DC Inhibit connector on the rear panel
8. al In this mode the Linear Gate normally blocks all input signals unless the Enable signal sets the Linear Gate to pass signals for a selected duration as set by the Pulse Width control after receiving an Enable pulse Pulse Inhibit The reciprocal of the Normal mode is available with the switch in this position i e the Linear Gate passes all signals except when a pulse is applied to the Enable input The pulse on the Enable input causes the gate to block the passage of signals through the Linear Gate for a duration set by the Pulse Width adjustment DC Inhibit This mode is identical to the Pulse Inhibit mode except that the application of an inhibit or block input must be made on the rear panel BNC connector and the Linear Gate will remain blocked for the duration that the dc signal is applied to the DC Inhibit Input connector For applications where the Linear Gate is desired to be switched for Normal i e selectively passing to a condition of passing all signals the switch should be operated between Normal and DC Inhibit position and there should be no connection on the DC Inhibit Input rear panel connector 4 2 INITIAL TESTING AND OBSERVATION OF PULSE WAVEFORMS See Sections 5 1 and 5 2 for test performance data 4 3 CONNECTOR DATA CN1 Input BNC Connector AC coupled linear gate input input impedance gt 5000Q input rated voltage range 0 2 to 10 V maximum input 12 V To minimize reflections when driving from low i
9. at provides a variable gate duration whose width is controlled by a single turn front panel mounted potentiometer The nominal gate duration range is from 0 3 to 4 usec Operation of the Linear Gate is controlled by the application of a positive Enable pulse The Linear Gate is useful in applications that require inhibiting a linear signal according to chosen coincidence or timing requirements e g reducing the counting rate in subsequent linear analysis equipment The 426 is designed to meet the recommended interchangeability standards of USAEC Report TID 20893 Rev An ORTEC 4001 4002 Series Bin and Power Supply provides all necessary power through the rear module power connector All signal levels and impedances are compatible with other modules in the ORTEC 400 series The basic function of the 426 is to accept all pulse shapes existing in the ORTEC 400 Series linear function modules If the input signal is bipolar the negative portion will not be passed through the Linear Gate The input impedance is greater than 5000Q and the input is normally sent from the factory ac coupled The input can be operated dc coupled if desired refer to Section 4 4 A dc restoration network at the input reduces baseline shift at high counting rates The restoration network works on both unipolar and bipolar input pulse shapes The Linear Gate proper consists of a series parallel saturated transistor switch This switch network incorporates an
10. bly can best be avoided by terminating the driving cable at the Enable input with the characteristic impedance of the driving cable The amplitude and width of the Enable input signal are specified in Section 2 The maximum width of the Enable input is not specified in Section 2 and indeed may be any width since the Enable signal is regenerated to allow gate width duration to be independent of the pulse shape of the Enable input The minimum recommended width of the Enable input is 50 nsec measured at 50 amplitude although narrower pulses with larger amplitude will trigger the Enable circuitry 3 4 LOGIC INPUTS TO THE DC INHIBIT INPUT The same considerations of Section 3 3 apply to input pulses to the DC Inhibit Input connector This input provides the facility to block the passage of signals through the Linear Gate by the application of a dc voltage either in the basic form of a battery and switch contact or by the application of a pulse waveform between dc voltage levels The input is dc coupled and has an impedance of approximately 650Q A maximum dc voltage of 20 V is allowed on this input A DC Inhibit control is not regenerated internally but exists throughout the duration of the inhibiting signal 3 5 LINEAR OUTPUT SIGNAL CONNECTIONS AND TERMINATING IMPEDANCE CONSIDERATIONS The source impedance of the 0 to 10 V standard linear outputs of most 400 Series modules is approximately 1 Interconnection of linear signals is t
11. ceiving end only when it is essentially unloaded or loaded with an impedance many times of the cable This may be accomplished by inserting a series resistor equal to the characteristic impedance of the cable internally in the module between the actual amplifier output on the etched board and the output connector Remember that this impedance is in series with the input impedance of the load being driven and in the case where the driven load is 900Q a decrease in the signal span of approximately 10 will occur for a 93Q transmission line A more serious loss occurs when the driven load is 93Q and the transmission system is 93Q in this case a 50 loss will occur BNC connectors with internal terminators are available from a number of connector manufacturers in nominal values of 50 100 and 1000Q ORTEC stocks in limited quantity both the 50 and 1000 BNC terminators The BNC terminators are quite convenient to use in conjunction with a BNC tee 4 OPERATION 4 1 FRONT PANEL CONTROLS Gate Width A single turn potentiometer provided to adjust the gate width to the desired value within the nominal range of 0 3 to 4 Usec This control is recess mounted and as such is a screwdriver adjustment but it may be panel mounted so that a knob may be added to the potentiometer shaft to allow finger thumb adjustment if this seems desirable Mode Switch A 3 position switch used to set the Linear Gate into one of the following operation modes Norm
12. educed to a negligible value typically 1 mV R11 is located near the top of the etched circuit board To adjust the pedestal it is necessary to open the Linear Gate with no input signal feeding into the Linear Gate input CN1 while observing with an oscilloscope the output of the Linear Gate Observing the Linear Gate output adjust the pedestal trim potentiometer until the pedestal is reduced to a negligible amount 5 4 TABULATED TEST POINT VOLTAGES The following voltages are intended to indicate the typical dc voltages measured on the etched circuit board In some cases the circuit will perform satisfactorily even though due to component variations some voltages may measure outside the given limits Therefore the voltages given should not be taken as absolute values but rather as an aid in troubleshooting 5 5 SUGGESTIONS FOR TROUBLESHOOTING In situations where the 426 is suspected of malfunction it is essential to verify such malfunction in terms of simple pulse generator impulses at the input and output In consideration of this the 426 must be disconnected from its position in any 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 amplifier Linear Gate system and the logic system perform satisfactorily with the test pulse generator The testing instructions in Section 5 1 of this manual provide
13. hus noncritical since the input impedance of circuits to be driven is not important in determining the actual signal span e g 0 10 V delivered to the following circuit Paralleling several loads on a single output is therefore permissible while preserving the 0 10 V signal span Short lengths of interconnecting coaxial cable up to approximately 4 ft need not be terminated If however a cable longer than approximately 4 ft is necessary on a linear output it should be terminated in a resistive load equal to the cable impedance Since the output impedance is not purely resistive and is slightly different for each individual module when a certain given length of coaxial cable is connected and is not terminated in the characteristic impedance of the cable oscillations will generally be observed These oscillations can be suppressed for any length of cable by properly terminating the cable either in series at the sending end or in shunt at the receiving end of the line To properly terminate the cable at the receiving end it may be necessary to consider the input impedance of the driven circuit choosing an additional parallel resistor to make the combination produce the desired termination resistance Series terminating the cable at the sending end may be preferable in some cases where receiving end terminating is not desirable or possible When series termination at the sending end full signal span i e amplitude is obtained at the re
14. koff Table 5 1 Pin No Test Point Voltage V 1 Q7e 0 2 2 Q4b 0 61 3 Q5b 17 4 Q9c 109 5 Q12c 11 4 6 Q138 06 Note All voltages were measured from ground with vtvm having input impedance of 10 mM or greater Voltages are dc values with no input pulses The following preliminary procedures should be observed 1 Visually check module for possible damage due to shipment 2 Plug module into Bin and check for proper mechanical alignment 3 Connect ac power to ORTEC 4001 4002 Bin and Power Supply 4 Switch ac power on and check the dc power supply voltages at the test points on the Power Supply control panel on the 401 Use the following procedure to check the performance of the 426 1 Feed the 419 Pulse Generator output into the 410 Linear Amplifier Feed the Bipolar Output of the 410 into the 407 Crossover Pickoff Feed the Output from the 407 into the Enable input of the 426 Set the 410 pulse shaping mode to Double RC DRC Le Integrator First Differentiator and Second Differentiator to 0 2 Us 2 Also feed the Bipolar Output of the 410 into the ORTEC 427 Delay Amplifier The output of the 427 should be approximately 0 5 V 3 Observe the output of the 426 Adjust the trim potentiometer at the top of the board for a minimum pedestal 4 The amplitude of both the initial and final transient negative spikes should not exceed 300 mV 5 Feed the Output of the 427 into the linear Input of the 426
15. mpedance sources into this connector a terminator equal to the characteristic impedance of the driving cable should be shunted from this connector to ground CN2 Linear Gate Output BNC Connector DC coupled output output impedance lt 2Q positive output signals only with rated range of 0 2 to 10 V maximum output 12 V TP2 Linear Gate Output Test Point Oscilloscope test point for monitoring signal on linear gate output BNC connector CN2 This test point has 470Q series resistor connecting it to CN2 CN3 Enable Input BNC Connector DC coupled input impedance 1000Q requires a positive 2 V pulse maximum input 20 V CNA DC Inhibit Input BNC Connector DC coupled input impedance 650Q requires a positive 4 V pulse or dc level maximum input 20 V 4 4 TYPICAL OPERATING CONSIDERATIONS In the Normal mode the Linear Gate is opened i e passes input signals with the application of a positive pulse on the Enable input The duration that the Linear Gate will remain open is normally continuously variable from 0 3 to 4 Usec with the front panel control For other pulse widths refer to Section 6 2 Figure 4 1 illustrates the gating action of the Linear Gate Notice that only the positive portion of the input signal is passed through the Linear Gate The Linear Gate has an internal pedestal adjustment that allows the pedestal to be reduced to a negligible value refer to Section 6 2 for adjustment procedure Figure 4 2 shows the ou
16. n the ORTEC NIM standard modules In typical applications the output of the linear gate feeds a multichannel analyzer directly The output is also compatible with any of the linear modular circuitry in the ORTEC NIM standard modules 3 INSTALLATION The ORTEC 426 contains no internal power but is used in conjunction with an ORTEC 4001 4002 Series Bin and Power Supply which is intended for rack mounting Therefore if vacuum tube equipment is operated in the same rack with the 426 there must be sufficient cooling air circulating to prevent any localized heating of the all transistor circuitry used throughout the 426 The temperature of equipment mounted in racks can easily exceed 120 F 50 C unless precautions are taken The 426 should not be subjected to temperatures in excess of 120 F 50 C 3 1 CONNECTION TO POWER Turn off the Bin power supply when inserting or removing modules The ORTEC 400 Series is designed so that it is not possible to overload the Bin power supply with a full complement of modules in the Bin Since however this may not be the case when the Bin contains modules of other than ORTEC design the Power Supply voltages should be checked after the modules are inserted The 4001 4002 has test points on the Power Supply control panel to monitor the dc voltages When using the ORTEC 426 outside the Bin and Power Supply take care to ensure that the power jumper cable used properly accounts for the Power S
17. o make claim with the shipper Instruments not in warranty 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 WARRANTY SAFETY INSTRUCTIONS AND SYMBOLS SAFETY WARNINGS AND CLEANING INSTRUCTIONS 1 2 INSTALLATION MAINTENANCE CONTENTS DESGRIPTION ves cece eyed beee hee eRe da hehe ceded eS ERS ERE ER ERLE Le hehehehe ie bees eee SPECIFICATIONS EE 2 1 PERFORMANCE 2 2 CONTROLS eis EE eee beens oe ee bene Oe REE eee eee ee eRe ede bode does ZS INPUTS vias chee bees bee eee eee eee rer ETRE Ke eee DOeRE Eee EC ere EOE EE E 2A OUTPUT eege PERE E YEE Oe ee Pe he Se CORR es We Re We ee ae Pee ole SN 2 5 ELECTRICAL AND MECHANICAL
18. s assistance in locating the region of trouble and repairing the malfunction 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 the etched board 5 6 FACTORY REPAIR This instrument can be returned to the ORTEC factory for service and repair at a nominal cost Our standard procedure for repair ensures the same quality control and checkout that are used for a new instrument Always contact Customer Services at ORTEC 865 482 4411 before sending in an instrument for repair to obtain shipping instructions and so that the required Return Authorization Number can be assigned to the unit Write this number on the address label and on the package to ensure prompt attention when it reaches the ORTEC factory Bin Module Connector Pin Assignments For Standard Nuclear Instrument Modules per DOE ER 0457T 8 es oa E M ARON TRS 16 17 18 19 20 21 22 Function Spare bus Reserved bus Coaxial Coaxial Coaxial 200 V de Spare 6 V 6V Reserved bus Spare Spare Reserved 12 V 12V Spare bus Reserved bus Spare Spare Reserved 41 42 Function Reserved Reserved Reserved Spare Spare 24 V 24 V Spare bus Spare Spare 117 V ac hot Power return ground Reset Scaler Gate Reset Auxiliary Coaxial Coaxial Coaxial 117 V ac neutral High quality
19. the DC Inhibit Input connector the linear gate will pass a input signals This can be a very useful mode for setting up experiments since the proper timing of the input signal to the Enable input is not necessary to get an output signal A slight difference in the pedestal magnitude may be noticed when changing modes from Normal to DC Inhibit The pedestal is normally adjusted for minimum in the Normal mode but may be adjusted to suit the experiment in mode desired Notice that as supplied C6 is shorted with a jumper wire and the output is dc coupled There will be a small dc offset voltage that is dependent on the saturation properties of the gate transistors that will have to be considered when going into an ADC or other dc coupled units Capacitor C6 is provided to allow ac coupling in these cases but polarity of the offset must be determined to properly connect the solid tantalum electrolytic capacitor C6 5 MAINTENANCE 5 1 TESTING THE PERFORMANCE OF THE LINEAR GATE The following paragraphs are intended as an aid in the installation and checkout of the ORTEC 426 These instructions present information on front panel controls waveforms at test points and output connectors The following or equivalent test equipment is needed ORTEC 419 Pulse Generator Tektronix Model 580 Series Oscilloscope 1009 BNC Terminators Vacuum Tube Voltmeter ORTEC 410 Linear Amplifier ORTEC 427 Delay Amplifier ORTEC 407 Crossover Pic
20. tput of the Linear Gate with the pedestal properly adjusted and improperly adjusted The Linear Gate is usually operated in the normally closed mode with both input and output ac coupled Two variants of this mode are possible gate operating normally open i e normally passes all input signals except when accompanied by an enable or inhibit pulse and gate dc coupled operating either normally closed or normally open S a NPTT Fig 4 1 Gating Action of Linear Gate Scale 100 mV cm 500 nsec em 500 nsec cm b Pedestal Improperly Adjusted Fig 4 2 Output of Linear Gate Operation in the second mode requires modification to the actual etched circuit board For dc operation the input and output capacitors C1 and C6 must be replaced with jumper wires for a dc connection With this arrangement a small dc offset voltage from input to output will be observed approximately 160 mV and must be considered in the connection of the gate to the input and output equipment For operation in the Inhibit mode all input signals will be passed except when an inhibit signal is applied to either the Enable input or to the DC Inhibit Input The particular input depends on the position of the mode switch Enable input depends on the position of the mode switch Enable input for Pulse Inhibit position and DC Inhibit Input for the D C Inhibit position refer to Section 4 1 With the mode switch set to DC Inhibit and no input to
21. ty 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 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 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 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 Allow the instrument to dry completely before reconnecting it to the power source vi EN ELH LINEAR GATE IANHU3AIT If GATE WIDTH ORTEC 426 LINEAR GATE 1 DESCRIPTION The ORTEC 426 is a modular Linear Gate th
22. upply grounding circuits provided in the recommended standards of AEC TID 20893 Rev Both clean and dirty ground connections are provided to ensure proper reference voltage feedback into the Power Supply and these must be preserved in remote cable installations Be careful to avoid ground loops when the module is operated outside the Bin 3 2 INPUT SIGNAL CONNECTION TO LINEAR GATE The linear input to the ORTEC 426 is on the front panel BNC connector and is directly compatible with the output of all linear amplifiers biased amplifiers pulse stretchers and delay amplifiers with all linear circuitry found in the ORTEC 400 Series The Linear Gate passes only positive unipolar signals and or the positive portion of bipolar signals This must be kept in mind when putting in linear signals from other than ORTEC products The linear input to the 426 is ac coupled as normally supplied but may be dc coupled if desired If the linear input to the 426 is driven from a low driving impedance such as the output from an ORTEC 410 Linear Amplifier the 426 linear input should be terminated in the characteristic impedance of the connecting coaxial cable 3 3 LOGIC INPUT TO THE ENABLE INPUT The input pulses to the Enable input may come from any source of logic pulses The input impedance of the Enable input is 1000Q dc coupled and some care must be given to ensure that reflections do not occur in the driving transmission cable This proba
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