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1. doe ea TRI ORE Ae RAI S 1 2 5 Safety Consideration 1 2 6 Accessories Supplied 1 2 7 Specifications uu Gane ae he 1 2 ECTION 2 INSTALLATION 1 Introduction aes he 2 1 2 Unpacking and Initial Inspection 2 1 3 Performance Checks 2 1 3 Power Requirement a Abe ae wears 2 1 4 Line Voltage and Fuses eese x yp vex Hate oko eO E rex us 2 1 5 Grounding Requirements 2 2 6 Installation and Mounting 2 2 7 Bench Mounting 2 2 8 Rack Mounting 3 4 2 2 9 056 fara a tree mre eu Mine x dur uM e T 2 2 10 Short Term Storage acras s geom SIDE Som a E okck m ea UE eL 2 2 11 Long Term Storage or Re packing for Shipment 2 3 12 ctos get regi tog Area ae d d 2 4 ECTION 3 OPERATION 1 IntrOduUCtion 2 PPP 3 1 2 Front Panel Familiarization 3 1 2 1 CoOntrolss cs
2. 9 6 Keyboard and Display Components Location 9 7 Current Generator Board 9 8 Current Generator Board Components 9 9 cc 9 10 VCO Board Components Location 9 11 Output Amplifier Board 9 12 Output Amplifier Board Components 9 13 Pulse Generator Board 9 14 Pulse Generator Boar Components Location 9 15 vi Contents 1 1 2 1 3 1 3 2 3 3 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 5 2 5 3 7 2 7 3 8 1 Contents vii LIST OF TABLES Model 8550 8551 Specifications 1 3 Line Voltage and Fuse Selection 2 2 Default State After Software Reset 3 5 Front Panel Parameter Entry 3 9 Offset Amplitude Programming Limits 3 18 Model 8550 Interface Function lt 4 4 IEEE 488 contact Designation 4 5 IEEE 488 Bus Command Summary 4 6 Default conditions Status after SDC DCL or 5 4 8 Device Dependent Command Summary 4 13 Common Commands and Queries Summary
3. 5 9 Rise Fall Time Accuracy model 8551 5 10 PWM Characteristics model 8551 5 10 SECTION 6 THEORY OF OPERATION Introdiction a eee 6 1 Overall Functional Description 6 1 BO ALS ae tutes a Gh ODE ara ala a 6 1 Display and Keyboard Interface 6 3 Gounter Mk ere Bok E Rr de ee aoe Gab wasters 6 3 IEEE 488 Interface Bus GPIB 6 3 6 0 m OG tas dig Sk tee eed aoe 6 3 Voltage Controlled lt 6 3 Current Generator s ri dope t Et ion be eae eee ae 6 3 Range Capacitors and 6 4 Sine Shaper i ee A 6 4 Trigger and Burst Circuit 5 6 4 SYNC Output GIKGUlt utes Es meg 6 5 Auxiliary Circuits RE MOERS IE BAR E E Reg 6 5 Calibration Board kde hee Rm fasse xg 6 5 Reference Circuit 6 5 D A Parameter Control 6 5 Trigger Input CIFGulb uxo Gace we
4. 9 14 Pulse Generator Board Components 9 15 viii Contents General Information 1 1 INTRODUCTION This manual provides operation and maintenance information for both Model 8550 Function Generator and Model 8551 Pulse Function Generator Section 1 provides general description of the instruments Sections 2 and 3 contain installation and operation instructions IEEE 488 2 GPIB programming is ex plained in Section 4 Maintenance and performance checks are provided in section 5 Theory of operation is described in section 6 Section 7 outlines calibration and troubleshooting procedure Section 8 contain tables of replaceable parts and recommended spare parts Section 9 contains schematic and component location diagrams NOTE This manual is common to both Model 8550 and Model 8551 describes all features and functions for both models Therefore some features which are described in this manual may not be available in your instru ment Features that are unique to the Model 8551 are described sepa rately 1 2 DESCRIPTION Model 8550 is an extremely high performance programmable function generator It provides a variety of signal waveforms to be used as test stimuli for different electronic devices Microprocessor based Model 8550 is easy to set up for manual use is also simple to program in GPIB system environment The instrument is built in an all round metal
5. Figure 9 8 Current Generator Board ATGW3SSU 3018434399 1 799670990 73008 uL 1255 1859 054 694 929 m 8 f a Eg r 422 1554 e 569 865 za Figure 9 9 Current Generator Board Components Locati E oe Ig 16 F nm O O 2 oem gt TE Figure 9 10 VCO Board 2141 zs CSHMODEL 8550 85541 UCO ASSEMBL Figure 9 11 VCO Board Components Location Figure 9 12 Output Amplifier Board mp Bee Omm TOF em m 3 a eee 2 d Rae ero a Bx gt MODEL 8659 8551 OUTPUT AMPLIFIER ASSEMBLY 12 C642 c 5 61 2 R116 E 69 TR Figure 9 13 Output Amplifier Board Components Locatic ds i al ju 8 T 2 gt 69 Q9 tt 88020854 88 EEKE VERAM Figure 9 14 Pulse Generator Boarc 9 nad gS9rc 090TL 6 2 2074 Oper gt X 7 o o 42 2
6. 2 m 2 8 T 8 Figure 9 15 Pulse Generator Board Components Locatic
7. 4 19 Response Message Format Summary 4 23 HP s Model 8116A Mode Parameter 4 31 Une Fuse Selection We Re ae be Bat 5 1 Required Test Equipment 5 3 Rise Fall Time Accuracy 5 10 Recommended Test Equipment 7 1 Power Supply Checks 7 8 Digital Circuitry and Display 5 7 9 Model 8550 8551 List of 8 1 Model 8550 8551 Parts List 2 1 4 1 4 2 4 3 4 4 4 5 4 6 5 2 5 3 6 1 7 2 7 3 7 5 9 1 9 2 9 4 9 5 9 6 9 8 9 9 9 10 9 11 9 12 9 13 9 14 9 15 LIST OF FIGURES Line Voltage and Fuse 2 1 Model 8550 8551 Outline Dimensions 2 3 IEEE Bus Configuration 4 2 IEEE Handshake 4 3 IEEE 488 2 Status Reporting Model 4 25 Calibration Failure Status Registers Interpretation 4 28 Ramp Pulse Errors Status String ERR Interpretation 4 29 Machine Status String STT Interpretation 4 30 PLL Phase Offset Accuracy Check 5 7
8. 7 6 Amplitude Calibration Failures 7 6 Offset Calibration Failures 7 6 Phase Lock Offset Calibration Failures 7 7 Trigger Phase Offset Calibration Failures 7 7 Counted Burst Calibration Failures 7 7 Pulse Width Calibration Failures model 8551 7 7 Rise Fall Time Calibration Failures model 8551 7 7 General Troubleshooting Hints 7 8 Power Supply Checks 7 8 Digital Circuitry and Display Checks 7 9 Generali asf ts Sik By carts Doin edes Er RT Rer aly a Totes 8 1 Ordering Information 8 1 MendOrss fo occ axa ot dade ag ae AC CRIME aw owe AR e RATEN oes 8 1 Parts Description usus boh amp oe ad we eee RUP EORR 8 1 SECTION 9 SCHEMATIC DIAGRAMS 9 1 9 2 9 3 9 4 9 5 9 6 9 7 9 8 9 9 9 10 9 11 9 12 9 13 9 14 9 15 Main Board Power Supply 9 1 Main Board Inter Connection Diagram 9 2 Main Board Components Location 9 3 CPU Board 6 e xA RR uL Vie b de wed oe P ardet t tes 9 4 CPU Board Components Location 9 5 Keyboard and Display
9. wwe bees 4 17 4 10 4 Control Modes GT Res xe m 4 17 4 10 5 Output Waveforms W a 0 4 17 4 10 6 Output Mode DiC E ESI eddy fowl 4 17 4 10 7 Edge Gottrol EJ aia aa mo De eed og Bd s 4 17 4 10 8 Parameter Programming 4 17 4 10 9 Display Parameter V 4 18 4 10 10 Common Commands 4 19 4 10 10 1 Setups SAV RCL 4 20 4 11 Device Talking Formats 4 20 4 11 1 Functional Element Summary 4 20 4 11 2 Separator Functional Element Summary 4 21 4 11 2 1 Response Message Unit 5 4 21 4 11 2 2 Response Data Separator 4 21 4 11 2 3 Response Header Separator 4 21 4 11 3 Response Message Terminator 4 21 4 11 4 Response Header 25k ok Lor lo ee OS m 402 4 21 4 11 5 Response Data o kw RR a 4 21 4 11 5 1 Character Response 4 21 4 11 5 2 Decimal Numeric Response 4 22 4 12 Reading From the Model 8550 4 22 Contents iii 4
10. ONLY ABLE TO LISTEN DEVICE D ONLY ABLE DATA BYTE TRANSFER CONTROL GENERAL INTERFACE TO TALK MANAGEMENT Any given system can have only one controller control may be passed to an appropriate device through a special command Any number of talkers or listeners may be present up to the hardware constraints of the bus The bus is limited to 15 devices but this number may be reduced if higher than normal data transfer rates are required or if long interconnect cables are used Several devices may be commanded to listen at once but only one device may be a talker at any given time Otherwise communications would be scrambled much like an individual is trying to select a single conversation out of a large crowd Before a device can talk or listen it must be appropriately addressed Devices are selected on the basis of their primary address The addressed device is sent a talk or listen command derived from its primary address Normally each device on the bus has a unique primary address so that each may be addressed individually The bus also has another addressing mode called secondary addressing but not all devices use this addressing mode Once the device is addressed to talk or listen appropriate bus transactions may be initiated For example if an instrument is addressed to talk it will usually place its data on the bus one byte at
11. lt ni E lt J3 i lt E TO OISPLAY lt 2 BOARD lt a red IB gt 2 lt a EA 1 lt 1 cx eH 15 o lt Pi L3 gt NOLDEL CILE E co z Si iy 2 ka u RS 5 V Nano K E 1 5 V 95960408050 68090 E E yia 14 Figure 9 4 CPU Board gt o a 2 io 5 Q io io a Q 2 Figure 9 5 CPU Board Components Location 5400 HOSP 7501 HOSP 7507 MOSP SSO1 05 mm TRIG BUR TRIG LVL 061 054 INT TRIG sv RI 220 DISPLAY LEDS ORIVE Y ci 08 16 E nae 9 11 13 gt N C 5 057 15 25 29 32 35 3mm MINI LED RED SWITCHES MATRIX ALL THE REST RED LED MV 57124 19 144 TRIG MODE 01 010 2N4403 ca 0 1 Be ee OEP ER POO EEE IE 5v TO C P U BOARD PER SWP i Figure 9 6 Keyboard and Display 3 8 t B 3 5 LSBU ES 5 Figure 9 7 Keyboard and Display Components Location
12. SAVnn RCLnn Where nn may range from 00 to 30 nn is the selected memory cell of which the setup is to be stored or from where the setup is to be recalled 4 11 DEVICE TALKING FORMATS This paragraph discusses the formatting of Response Message elements sent from a device via its system interface Allowable IEEE 488 2 response message is composed of a sequence of lt Response Message gt units each unit representing a response to a query Each lt Response Message gt is composed of a se quence of functional syntactic elements Legal IEEE 4 20 GPIB Operation 488 2 Response Message is created from functional elements sequences A Response Message is in terpreted by a controller running an application pro gram and as such needs to convey its information precisely for consistent operation with a wide range of controllers Response Message therefore has a more restrictive format than Program Message Some queries of universal instrument system ap plication have been defined by the IEEE 488 2 They are the common queries these queries are specific path selections through the functional syntax diagram as specified in the IEEE 488 2 standard The re maining queries are device specific and are generated by the device designer using the functional syntax diagram and the needs of the device The functional elements include separators terminators headers and data types These elements are discussed in
13. feti ate deae ee ees 6 m d m 3 1 2 1 1 Operating Mode ave cS e Udo eus 3 1 2 1 2 Slate vec m et Mu ese esos VoM tad 3 1 2 1 3 Main Parameters Model 8550 3 1 2 1 3A Main Parameters Model 8551 3 3 2 1 4 Trigger Mode raea ee Rer RARO mox YD dod ee A 3 4 2 1 5 otium ae dioec 2 geh oe oan de af om auge 3 4 2 1 6 OU MEC IT 3 4 2 1 7 Modifier Ree i oe el Ss 3 4 2 2 Gornhectorsx taedet qw peru Ee x ru td a ep A Rc 3 4 2 8 Display And Indicators 255555 UE SIDA 3 5 3 Rear Panel Familiarization 3 6 3 1 Connectors and Switches 3 6 4 Procedure 522220 cn irem ade GOD do god age Red 3 6 5 software Reset acd cas bos OR OR ECL UR ees 3 7 5 1 Parameter Preset momo hot ep 3 7 6 Display Messages 3 7 7 Detecting Programming Errors 3 7 8 Front Panel Error Indication 3 7 8 1 General ERON i2 deum pack Rie E Rois Cup CURE dr 3 7 8 2 Limit Error
14. o o LINE SELECT 115 230V Figure 2 1 Line Voltage and Fuse Holder The instrument operates over the power mains frequency range of 50 to 400Hz Always verify that the operating power mains voltage is the same as that specified on the rear panel voltage selector Switch CAUTION Failure to switch the instrument to match the operating line voltage will damage the instrument and may void the warranty The Model 8550 should be operated from a power source with its neutral at or near ground earth potential The instrument is not intended for operation from two phases of a multi phase ac system or across the legs of a single phase three wire ac power System Crest factor ratio of peak voltage to rms should be typically within the range of 1 3 to 1 6 at 1096 of the nominal rms mains voltage Preparation 2 1 To change the line voltage disconnect the power cord from the Model 8550 slide the Line Select switch Figure 2 1 to the desired line voltage Also be sure to change the fuse see the following procedure To change the fuse perform the following steps 1 Disconnect the power cord from the instrument Remove the fuse from the fuse holder 2 Compare the ampere rating on the fuse to the ampere ratings given in Table 2 1 If the fuse is blown replace it by sliding the new fuse back into the fuse holder If the fuse is not blown and has the right rating keep it If the fuse has the wrong rating replace the
15. the owner Note the problem the pects of this instruction manual before using the symptoms and service or repair de instrument to assure operator safety and protection sired Record the model and serial against personnel shock hazard number of the instrument Show the 2 4 Preparation Operating Instructions Section 3 3 1 INTRODUCTION Model 8550 8551 operation is divided into two general categories basic bench operation and IEEE 488 operation Basic bench operation which is covered in this section explains how to use the model 8550 for generating the required waveform characteristics IEEE programming can also be used to greatly enhance the capability of the instrument in applications such as automatic test equipment This aspect is covered in details in Section 4 3 2 FRONT PANEL FAMILIARIZATION The front panel is generally divided into three sections controls connectors display and indicators The fol lowing paragraphs describe the purpose of each of these items in details 3 2 1 Controls All front panel controls except POWER are momentary contact switches Most controls include an annunciator light for indication of the selected parameter and operating mode Some controls do not have an annunciator light Exercising these controls generates an immediate response on the display Front panel controls may be divided into functional groups Operating mode State Main Parameters Trigger Mode Control Out
16. 0104 49910 0104 68110 0102 7321A 0104 90910 0104 10020 0104 20020 0104 51120 0104 10030 0104 10040 0113 03300 0203 0203A 0203 0202A 0203 0102A 0110 1102B 0500 56700 0500 91000 0500 56330 0540 01100 0500 53210 0500 11600 0500 56310 0500 60000 0500 56340 0500 60950 0500 56600 0500 56350 0500 45300 0500 45600 0500 45100 0500 40900 0500 50400 Vendor Code 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 96095 80294 80294 80294 91637 04713 17856 04713 27014 04713 04713 04713 36472 36472 1ES66 04713 24355 04713 04713 04713 04713 04713 Reference Qty Designation Rear Panel Assembly Table 8 2 Model 8551 Parts List continued Description and Commercial Part Number MAINS TRANSFORMER MAINS RECEPT amp FILTER 1 CON GPIB 57FE 2 0240 20ND35 SW LINE SELECT EPS1SL1 FUSE 1A 250V S B 5x20 218 001 FAN 12VDC ST 60X12A Model 8551 List of Assemblies Main Board Assembly C P U Board Assembly Current Generator Board Assembly V C O Board Assembly Pulse Generator Board Assembly Output Amplifier Board Assembly Front Panel Board Assembly Rear Panel Assembly Case Assembly Tabor Part Number 6100 6280 2500 05000 3000 20500 3000 40300 2000 10220 1100 15600 1700 00100 6100 61850 6100 62000 6100 62100 6100 62200 6100 62500 6100 62300 6100 61910 6100 62800 6100 62700 Vendor Code 23338 23338 61935 0355
17. 95 3 1 4W 1 100 196 1 4W 100 196 1 4W 121 1 4W 1 215 1 1 4W 0100 01020 0100 02220 0100 03320 0100 04720 0100 01030 0100 01040 0104 10R00 0104 24R30 0104 33R20 0104 49R90 0104 61R90 0104 61R9B 0104 71R50 0104 71R5A 0104 95R30 0104 10000 0105 10000 0104 12100 0104 21500 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 Parts List 8 7 Table 8 2 Model 8551 Parts List continued Reference Description and Tabor Designation Commercial Part Number Part Number Vendor Code R57 R121 RES 249 196 1 4W 0104 24900 74902 R10 R11 RES 442 196 1 4W 0104 44200 74902 R31 R32 RES 499 1 1 4W 0105 49900 74902 R35 R36 RES 750 1 1 4W 0104 75100 74902 R2 R7 825 196 1 4W 0104 82500 74902 R63 R64 R66 79 R104 105 R119 1K 196 1 4W 0104 10010 74902 R92 1 15K 1 4W 196 0104 11510 74902 R73 1 33 1 1 4W 0105 13310 74902 R86 R87 1 5K 1 2W 1 0104 1501A 74902 2K 196 1 4W 0104 20010 74902 2 49K 1 1 4W 0104 24910 74902 6 34K 1 1 2W 0104 6341A 74902 10K 196 1 4W 0104 10020 74902 20K 196 1 4W 0104 20020 74902 24K 196 1 4W 0105 24020 74902 VAR 100R 3386 W 0203 0101A 80294 VAR 200 3386W 1 201 0203 0201A 80294 VAR 2K3386W 0203 0202A 80294 RES NET MSP 05 01 33G 33K 5 0110 0333B 91637 ANALOG SWITCH SD5000N 0500 57110 17856 DAC AD834 0500 60100 24355 QUAD COMP LM339N 0500 50400 04713 8 BIT SHIFT REGISTER CD4094B 0540 01100 27014 DUA
18. Description Calibration query Standard event status enable query Standard event status register query Identification query Operation complete query Service request enable query Read status byte query Self test query No mask ESB bit set on operation complete Not used ESB bit set on query error ESB bit set on device dependent error ESB bit set on execution error ESB bit set on command error ESB bit set on user request ESB bit set on power on Mask not available Mask not available Mask not available No mask RQS MSS bit set on ERR bit RQS MSS bit set on FSC bit fail status byte C RQS MSS bit set on FSB bit fail status byte B RQS MSS bit set on FSA bit fail status byte A RQS MSS bit set on MAV bit message available RQS MSS bit set on ESB bit standard event status register Not used 4 16 GPIB Operation FO Normal operating mode F1 Linear sweep mode F2 Logarithmic sweep mode F3 Phase locking generator mode The model 8551 operating mode may be pro grammed by sending one of the following commands FO Normal operating mode F1 Variable duty cycle pulse generator mode F2 Fixed duty cycle pulse generator mode F3 Phase locking generator mode 4 10 2 Sweep Direction S ll Model 8550 while being used in one of its sweep modes provides a selection from four different sweep directions The sweep direction command controls the direction of which the output will sweep The s
19. Frequency calibration error Bit 1 Amplitude calibration error Bit 2 Offset calibration error Bit 3 PLL calibration error Bit 4 Trigger calibration error Bit 5 Pulse width calibration error Bit 6 Rise Fall time calibration error Bit 7 Not used IDN Identification Query Causes the generator to respond with its identity The returned data is organized into four fields separated by commas The unit must respond with its manufacturer and model number in the first two fields and may also report its serial number and options in field three and four If the later information is not available the GPIB Operation 4 23 device must return an ASCII 0 for each For example model 8551 response to is Ta bor 8551 0 REV1 1 OPC Operation Complete Query causes the device to generate the operation complete message in the Standard Event Status Register when all pending selected device operations have been fin ished SRE Service Request Enable Query enables the user to read the contents of the Service Request Enable register The device returns a number in the range of 0 to 63 or 128 to 191 since bit 6 RSQ cannot be set The binary equivalent of the number represents the value of the bits of the Service Request Enable Register STB Read Status Byte Query Reads the status byte containing the master summary status MSS bit The device responds with an integer in the range of 0 to 255 whose
20. Output Waveforms W The output waveform command give the user control over the output waveform The seven parameters which are associated with the waveform commands set the instrument to output sinewave triangle squarewave positive pulse negative pulse DC model 8550 only and ramp model 8551 only The output waveform may be programmed by sending one of the following commands 0 DC output model 8550 only W1 Sinewave W2 Triangle Square wave W4 Fixed base line positive square wave W5 Fixed base line negative square wave W5 Ramp output model 8551 only 4 10 6 Output Mode D C The output mode command places the function gen erator in stand by mode In model 8551 this command places the output in pulse complement mode and in inverted ramp mode The output mode may be programmed by sending one of the following com mands DO Normal output D1 Disabled output ll CO Pulse Ramp complement OFF mode 8551 only Ci Pulse Ramp Complement ON model 8551 only 4 10 7 Edge Control L Model 8551 when set to operate as a pulse generator may be placed in linear transition times mode Rise or fall times may be independently controlled for each edge or be set to fixed fast transitions The edge control command places the pulse generator in linear transition times mode Model 8551 may be programmed by sending one of the following com mands LO Fastest edge transitions L1 Linear
21. SECTION 7 ADJUSTMENTS 7 1 7 2 7 2 1 7 2 2 7 2 3 7 2 4 7 3 7 3 1 7 3 2 7 3 3 7 3 4 7 3 5 7 3 6 7 4 7 4 1 7 4 2 7 5 7 5 1 7 5 2 7 5 3 7 5 4 7 5 5 7 5 6 7 5 7 7 5 8 7 6 7 6 1 7 6 2 SECTION 8 PARTS LIST 8 1 8 2 8 3 8 4 Introduction uuo a eee ee ee eee 2 2 7 1 Adjustments Re Rom dece ee RR 4 7 1 Environmental Conditions 7 1 Warm p Period 1 uio kb eg 7 1 Recommended Test Equipment 7 1 Adjustment Procedures 7 1 Adjustment Procedure i e doc nexa EAR RT X dee Y es 7 2 Distortion Adjustment 2o i ex LA oe EU qx RE 7 2 Sine Level Adjustment 7 2 Squarewave Response 7 2 Pulse Width Adjustment model 8551 7 8 Ramp Base Line Adjustment model 8551 7 4 Reference Oscillator Adjustment 7 4 Trouble stiootitig Rc RV xm ERU nO RUE a 7 5 Recommended Test Equipment 7 5 Fowersup Tests o omes Ges Med 7 5 Troubleshooting Using the Self Diagnostics Function 7 5 Frequency Calibration Failures
22. a small amount of power No special cooling is required However the instrument should not be operated where the ambient temperature exceeds 40 C when the relative humidity exceeds 855096 or condensation appears anywhere on the instrument Avoid operating the instrument close to strong mag netic fields which may be found near high power equipment such as motors pumps solenoids or high power cables Use care when rack mounting to locate the instrument away from sources of ex cessive heat or magnetic fields Always leave 4 cm 1 5 inches of ventilation space on all sides of the instrument 2 7 BENCH OPERATION The Model 8550 8551 is shipped with plastic feet tilt stand in place and ready for use as a bench or portable instrument See outline drawing Figure 2 1 for dimensions 2 8 RACK MOUNTING The instrument may be rack mounted in a standard 19 inch rack The instrument may be rack mounted in Rack Mount Kit option 001 2 9 PORTABLE USE The instrument may be used in applications requiring portability A tilt stand consisting of two retractable legs is provided with each unit 2 10 SHORT TERM STORAGE If the instrument is to be stored for a short period of time less than three months place cardboard over the panel and cover the instrument with suitable protective covering such as a plastic bag or strong craft paper Place power cable and other accessories with the instrument Store the covered voltmeter in a clean
23. and observe that the generator displays the following message CAL The question mark appears blinking indicating that the instrument has not yet commenced with its calibration routine Depress the EXE push button and observe that the blinking question mark is re placed by a rotating LED bar The bar rotates as long as the self calibration program is in process If a calibration failure was detected the generator displays the following message FAIL d Where d represents a blinking digit in the range of 1 through 9 A function LED indicator in the front panel MAIN PARAMETERS block blinks simultane ously indicating the source of the calibration failure For example FREQ indicator that blinks with a display reading of FAIL 2 indicates that some circuits that generate the second frequency range failed to perform properly Adjustments and Troubleshooting 7 5 One may examine the full list of calibration failures immediately after a self calibration program was exe cuted or at any later time provided however that the CLS common command was not used before the list have been evaluated To examine the full list of calibration failures immediately after a self calibration program was executed depress the FAIL LIST 1 or the FAIL LIST push buttons The following paragraphs describe each failure and give some ideas how to locate the source of the failure Whenever necessary refer to the detailed sche matic diag
24. changing its state and reverse biasing diode CR10 then the positive going charging current which was flowing through CR10 is diverted to the timing ca pacitor allowing the VCO to oscillate until the next positive transition at the output of U13 This new transition sets U16a back to logic level 1 and clamps the VCO to a non oscillating status Gated Mode Gated mode operation is very much similar to the triggered mode operation except that a stable gating level is applied to the reset input of U16a As long as the reset level is set to logic level the VCO oscillates When the reset level is set to logic level 0 The VCO stops its oscillation after the last waveform is completed Burst Mode In this mode the differentiated triggering signal is applied to reset input of both U16a and U16b Q26 no longer keeps the D input of U16a at a logic level 1 U16a output is at logic level 1 and the VCO does not oscillate A trigger signal resets U16a U16b enables the VCO however because the D input of U16a is now set to logic level 0 the pulses from the VCO cannot set U16a to logic level 1 and cannot interrupt the VCO oscillation The VCO pulses are then routed through the gate U21c to the burst counter which is made of U19 U20 and U22 and to the gates U21a and U21b In parallel the VCO pulses are applied to the clock input of U16b When the burst counter reaches its maximum possible count FFF the next
25. component is left to the technician 7 4 1 Recommended Test Equipment The success or failure in troubleshooting a complex piece of equipment like the Model 8550 8551 de pends not only on the skills of the technician but also relies heavily on accurate reliable test equipment Table 5 2 lists the recommended test equipment for a complete troubleshooting and adjustment of the Model 8550 8551 However it is also possible to troubleshoot Model 8550 8551 with the minimum equipment which is listed in Table 7 1 Other equip ment such as logic analyzer and in circuit emulator etc could also be helpful in difficult situation 7 4 2 Power up tests Upon power up the Model 8550 8551 performs a set of tests which is described in paragraph 3 4 If the instrument locks up due to ROM or RAM fail there is a little point in attempting to troubleshoot elsewhere unless the microcontroller circuit is operating properly 7 5 TROUBLESHOOTING USING THE SELF DIAGNOSTICS FUNCTION An advanced feature of the Model 8550 8551 is its self diagnostics capability This feature helps in re ducing troubleshooting time of faulty circuits to mini mum The self diagnostics feature is a derivative of the self calibration function If for whatever reason the instrument can not calibrate itself to some built in calibration limits it automatically generates a failure list This list can later be examined using front panel programming sequence Calibration
26. the instrument is operational and within specification it is still recommended that the function generator will be checked periodically by certified calibration laboratories Suggested calibration period by certified calibration laboratories is given in Section 5 of this manual The auto calibration takes only few seconds to complete It therefore could be used often without serious delay to its normal operation However the auto calibration function must be operated when one or more of the following conditions occur 1 After 30 minutes of warm up time 2 After 24 hours of last internal auto calibration 3 If ambient temperature changes by more than and 4 After replacing components or sub assemblies To operate the auto calibration function proceed with the following steps PARAMETER LOW LIMIT FRQ frequency 10 00mHz AMP amplitude 10 0mV OFS offset 0 0mV OFS offset OmV PLL phase offset 0 PER period 99 99s WID pulse ramp width 999ms DTY duty Cycle 1 LEE leading edge 99 9ms TRE trailing edge 99 9ms RPT internal trigger period 999s BUR counted burst 1 TLV trigger level 0 0mV TPH trigger phase offset 0 DCO dc output level 0 0mV STP log sweep stop 10 00mHz SSN lin sweep stop SWT sweep time MRK log marker freq MKN lin marker freq SAV store 00 RCL recall 00 10ms 10 00mHz 10 display counts 10 display counts HIGH LIMIT REMARKS 50 00MHz 16 0V In
27. troller can for example send a query command to the device and then wait for MAV to become true If an application program begins a read operation of the output queue without first checking for MAV all system bus activity is held up until the device responds Bit 5 Standard Event Status Bit ESB Sum mary Message The ESB summary message is an IEEE 488 2 defined message Its state indicates whether or not one or more of the enabled ESB events have occurred since the last reading or clearing of the Standard Event Status Register Bit 6 Master Summary Status MSS Request Service RQS Bit Its state indicate if the device 4 26 GPIB Operation has at least one condition to request service The MSS bit is not part of the IEEE 488 1 status byte and will not be sent in response to a serial poll The RQS bit however if set will be sent in response to a serial poll Bit 7 Not used 4 14 1 Reading the Status Byte Register The Status Byte Register can be read with either a serial poll or the STB common query Both of these methods read the IEEE 488 1 STB message The value sent for the bit 6 position is however dependent upon the method used 4 14 1 1 Reading with a Serial Poll When serial polled the generator returns the 7 bit status byte plus the single bit RQS message The status bye and RQS message are returned to the controller as a single data byte The RQS message is sent on line D107 bit 6 RQS TRUE means th
28. 04713 U3 U15 U17 QUAD OP AMP LM324N 0500 53210 04713 U18 ECL FLIP FLOP MC10H131P 0500 45300 04713 U19 U21 OP TL081CP 0500 56700 04713 8 10 Parts List Table 8 2 Model 8551 Parts List continued Reference Description and Tabor Qty Designation Commercial Part Number Part Number Vendor Code COMPARATOR MAX9690CPA 0500 60950 1ES66 OP AMP LM 741C 0500 56310 04713 ANALOG SWITCH DG411CJ 0500 91000 17856 DUAL OP AMP TLO82CP 0500 56600 04713 1 1 1 1 CPU Board Assembly 6100 6200 C1 2 C4 14 CER 0 1u SR155C104ZAA 1500 01040 C3 CAP TANT 3 34 T350A335M025AS 1540 03350 C15 CAP ELECTR 470 25V 2222 037 1533 04770 CON FEMALE 2X8 90152 2216 3000 30520 CON MALE 2X10 90131 0770 3000 30260 CON MALE 2X13 90131 0773 3000 30290 TSTR 904 0400 01200 TSTR 2N4401 0400 01810 RES COMP 3 3K 5 1 4W 0100 03320 RES COMP 1K 5 1 4W 0100 01020 RES COMP 510 5 1 4W 0100 05110 RES NET MDP 16 03 150G 15 16 0109 01500 BUFFER ULN2004N 0500 11600 KEYBOARD DISPLY P8279 0500 20700 7415138 0510 02700 74 4049 0520 07300 CONTROLLER P8031 0500 21410 COUNTER DIVIDER 74HC4040 0520 07000 LOW POWER SCHOTTKEY 74LS373 0510 03650 EPROM 27C512 0500 21250 RAM MKA48ZO2B 200PSI 0500 11160 32BIT BINARY COUNTER 157062 0550 00300 741502 0510 00110 741500 0510 00100 74 74 0500 12600 GPIB CONTROLLER P8291A 0500 21300 GPIB BUFFER DS75161N 0500 21520 GPIB BUFFER DS75160N 0500 21510 CRYSTAL 10MHz CY 12A 0
29. 1 Using the Modifier The modifier group consists of three sets of push buttons each having its top button marked with an arrow pointing up and its bottom key marked with an arrow pointing down U These modifier push button control the displayed readout within a selected range The x1 1 or x1 0 push buttons when depressed and released once increment or decrement the least significant digit on the numeric display Depressing these buttons for more than one second modifies this digit constantly until the button is released or until the parameter limit is encountered Incrementing the x1 above 9 carries 1 to the second digit The x10 1 or x10 U push buttons control the second digit Their operation is similar to the x1 operation Incriminating the x10 above 9 carries 1 to the second digit x100 1 or x100 push buttons control the third and the fourth most significant digit 3 12 2 Modifying the Range The RANGE buttons control the range of the dis played parameter Depressing and releasing the RANGE 1 or the RANGE U buttons increases or decreases respectively the displayed range Depress ing these buttons when the generator is already at its highest or lowest range produces no further change 3 12 3 Parameter Limits In general parameters were assigned definite bounda ries The instrument was design in such a way that front panel programming under no circumstances may lead to an
30. 4 4 INTERFACE FUNCTION CODES The interface function codes are part of the IEEE 488 2 standards These codes define an instrument s ability to support various interface functions and should not be confused with programming commands found elsewhere in this manual Table 4 1 lists the codes for the Model 8550 The numeric value following each one or two letter code define Model 8550 capability as follows SH Source Handshake Function The ability for the Model 8550 to initiate the transfer of mes sage data on the data bus provided by the SH function AH Acceptor Handshake Function The ability for the Model 8550 to guarantee proper reception of message data on the data bus provided by the AH function T Talker Function The ability of the Model 8550 to send device dependent data over the bus to another device is provided by the T function Model 8550 talker capabilities exist only after the instrument has been addressed to talk L Listen Function The ability of the Model 8550 to receive device dependent data over the bus from anther device is provided by the L function Listener function capability of the Model 8550 exist only after it has been addressed to listen RS Service Request Function The ability of the Model 8550 to request service from the controller is provided by the RS function RL Remote Local Function The ability of the Model 8550 to be placed in remote or local modes is provided by
31. 8 6 Common Commands and Queries 4 9 4 9 Device Listening Format 4 9 4 9 1 Functional Element Summary 4 9 4 9 2 Separator Functional Element Summary 4 10 4 9 2 1 Program Message Unit 4 10 4 9 2 2 Program Data ee 4 10 4 9 2 3 Program Header Separator 4 10 4 9 3 Program Message Terminator 4 10 4 9 4 Command Program Header 4 11 4 9 5 Query Program Header 4 11 4 9 6 Program Data x esee ommno VOX X OR 404 4 11 4 9 6 1 Character Program 4 11 4 9 6 2 Decimal Numeric Program Data 4 11 4 9 6 3 Suffix ProgramData ea A Rug 4 11 4 9 6 4 Non Decimal Numeric Program 4 12 4 9 6 5 Arbitrary Numeric Program Data 4 12 4 9 6 6 Expression Program Data 4 12 4 10 Device Dependent Command Programming 4 12 4 10 1 Operating Mode 4 12 4 10 2 Sweep Direction 5 suceso 4 24 4 17 4 10 3 Trigger Mode osi wwe
32. 95051 Greenway Road Boone North Carolina 28607 Holzhauser Strasse 62 32 D 1000 Berlin 72 Germany 2835 Kemet Way Simpson Ville South Carolina 29681 800 Northwest HWY Des Plannes Illinois 60016 1235 Walt Whitman Road Melville New York 11747 CAGE Code 1CD05 03554 24355 96095 70903 80294 62839 05245 14655 75378 91637 74970 14936 12617 36472 50434 34649 34649 74902 31433 75915 55261 Parts List 8 1 Table 8 1 Model 8551 List of Vendors continued Vendor Address CAGE Code Maxim 120 San Gabriel Drive Sunnyvale California 94086 1ES66 Molex 2222 Wellington Court Lisle Illinois 60532 27264 Motorola 5006East McDowell Road Phoenix Arizona 85008 04713 National Semiconductors 2900 Semiconductor Drive Santa Clara California 95051 27D14 North American Philips Corp 7158 Merchant Avenue El Paso Texas 79915 59821 Projects Unlimited 3860 Wyse Road Dayton Ohio 45414 04597 Seiko Instruments 2990 W Lomita Blvd SGS 1000 East Bell Road Phoenix Arizona 85022 66958 SGS Thompson Micro Elctr 1310 Electronics Drive Carrollton Texas 75006 5D590 Shurter AG Werkhofstasse 8 CH 6002 Luzern Switzerland 61935 Signetics 811 East Argus Avenue Sunnyvale California 94088 18324 Siliconix 2201 Laurelwood Road Santa Clara California 95054 17856 Sprague Electronics 61 Split Brook Road STE 305 Nashua NH 3060 56289 Switchcraft Inc 5555 N Ellstone Avenue Chicago IL 60630 82389 Takamisawa 18 7 Kamium 3 Chome Setagaya ku Tokyo 154 J
33. Burst Characteristics 5 5 5 9 8 1 External Trigget e ERR 5 5 5 9 8 2 External Gate zo os ee pP REGNO S eue e 5 5 5 9 8 3 Extermal B rst 2e ence vm xe yop x gsx gu of dee ey 5 5 5 9 9 Internal Trigger Burst Characteristics 5 6 5 9 9 1 Internal 5 6 5 9 9 2 Internal 2 2 2222 4 24 4 4 5 6 5 9 10 Manual Trigger Gate Burst 5 6 5 9 10 1 Manual Trigget ee OE SO 5 6 5 9 10 2 Manual Gate a TO 4 RE IE e E 5 6 5 9 10 3 Mari al B rst ur sure Ge ER 5 6 iv Contents 5 9 11 5 9 12 5 9 13 5 9 14 5 9 15 5 9 16 5 9 17 5 9 18 6 1 6 2 6 3 6 3 1 6 3 2 6 3 3 6 4 6 4 1 6 4 2 6 6 1 6 6 2 6 6 3 6 6 4 6 6 5 6 6 6 6 6 7 6 7 6 7 1 6 7 2 6 7 3 6 8 6 8 1 6 8 2 6 8 3 6 8 4 6 8 5 6 8 6 Trigger Start Phase Offset Accuracy 5 6 Phase Lock Loop Characteristics 5 7 Amplitude Modulation Characteristics 5 8 FM an VCO Characteristics 5 8 Sweep Characteristics model 8550 5 9 Pulse Width Accuracy model 8551
34. INDICATION In general whenever a front panel or GPIB pro gramming attempts to place the 8550 in an error condition the Model 8550 responds by front panel error indication or by addressing the IEEE 488 2 service request register Errors are categorized in four main groups 1 General errors 2 Limit errors 3 Pulse Ramp setup errors 4 IEEE errors 5 Auto Calibration errors 3 8 1 General Errors Errors in this group are caused by improper usage of the instrument Such errors occur while attempting to place the instrument in an illegal mode For example depressing simultaneously two push buttons Operating Instructions 3 7 except AUTOCAL has no valid definition or by depressing the MANUAL push button while the in strument is in its continuous operating mode In such cases the instrument sounds an audible alarm ignores this error and continues with its normal operation 3 8 2 Limit Errors Errors in this group are caused by an attempt to program values outside the legal limits of the instru ment The instrument automatically rejects any attempt to program such parameters sounds an audible alarm and then resumes normal operation Table 3 2 summarizes all front panel entry limits 3 8 3 Pulse Ramp Set up Errors Model 8551 only The pulse ramp setup errors are inter parameter in consistencies errors such as pulse width greater than the selected period The pulse generator tests the programmed parameter
35. MAN push button is depressed the output generates a train of counted waveforms at programmable intervals The MAN push button has no effect in normal mode of operation or when the instrument is set to internal trigger mode 3 18 USING THE OFFSET The function generator employs two level windows allowing amplitude and offset to be independently selected within these levels When setting up the offset parameter one must keep in mind that the offset is attenuated with the signal The user has no control over the selected internal amplitude range This may cause some confusion since not knowing this fact may produce an offset error at an ampli tude offset combination that seems to be reasonable It is therefore suggested to first set up the amplitude parameter and only then to set the required offset level An attempt to modify the offset parameter beyond the capability of the instrument will generate an error indication Offsets and amplitudes are in dependently selectable within the level windows given in Table 3 3 3 19 USING FRONT PANEL SET UPS Setting up all parameters in a versatile instrument such as the Model 8550 8551 takes some time The set up time is longer when a number of tests are performed and more than one setup is required The function generator incorporates a non volatile memory that preserves stored information for a long time The size of the non volatile memory permits storage of up to 30 complete front panel
36. Modifier The MODIFIER push buttons simulate digital poten tiometers The MODIFIER push buttons operate in conjunction with the MAIN PARAMETER group There are four sets of modifying buttons Three sets are dedicated for changing the displayed read out The two push buttons which are marked RANGE are used to change the range of the displayed parameter 3 2 2 Connectors The connectors are used for connecting the Model 8550 to the unit under test to a control device and to an external triggering stimulant 1 TRIG REF INPUT The TRIG REF INPUT connector is used for applying an external triggering source to the function generator The same connector is used in conjunction with the phase lock operating mode the reference signal is applied to this connector 2 MOD INPUT The MOD INPUT connector is used for applying external controlling signals to the FUNCTION Function Parameters FREQ AMPL OFST Sweep Parameters Phase Parameters PLL Model 8550 P OFST Model 8551 TRIG Model 8550 Trigger Parameters PER BUR LEVEL PHAS Model 8551 Pulse Ramp Parameters PER Model 8551 WIDTH Model 8551 DUTY Model 8551 Operating Mode State Display Trigger Mode Control Output ST BY lable 3 1 Default States After Software Reset DESCRIPTION DEFAULT STATE Frequency 1 000KHz Amplitude 1 00V Offset OmV Sweep Stop Frequency 9 000KHz Sweep Time 1 00s Sweep Marker Frequency 5 000KHz Phase Lock
37. Phase Lock Loop Operation Check 5 8 Amplitude Modulation Operation Check 5 8 Model 8550 8551 Simplified Block Diagram 6 2 Connection Distortion Adjustment 7 2 Connection Sine Level Adjustment 7 3 Connection Squarewave Adjustment 7 3 Connection Pulsewidth Ramp Adjustment 7 4 Connection Reference Oscillator 7 4 Main Board Power Supply 9 1 Main Board Inter Connection Diagram 9 2 Main Board Components Location 9 3 CPU Board uc a Mek Beers dane dole E 9 4 CPU Board Components Location 9 5 Keyboard and Display 9 6 Keyboard and Display Components Location 9 7 Current Generator Board 9 8 Current Generator Board Components Location 9 9 Board egg ce ee a ie ee oe ee be mw 9 10 VCO Board Components Location 9 11 Output Amplifier Board 9 12 Output Amplifier Board Components 9 13 Pulse Generator Board
38. VCO positive going transition sets the Q output of U16b to logic level 1 creating conditions for U16a to be set to logic level 1 and to stop the VCO oscillation 6 4 6 SYNC Output Circuit The SYNC output generates a fixed voltage level signal having a sharp and defined transitions which are synchronous with the positive transitions at the main output connector The signal from the VCO circuit is routed to the SYNC amplifier circuit via a selector U27a U27b and U27c In continuous mode the SYNC signal is taken from the VCO circuit in gated and triggered modes the signal is shaped and taken from the trigger input signal in burst mode the SYNC signal is taken from the burst circuit with duration equal to the burst length The SYNC signal is then coupled through U27d to the SYNC amplifier which is made of Q29 through Q32 and their as sociated components 6 4 7 Auxiliary Circuits The information for the various gates and digital controls is received from the CPU board in a form of serial data The serial data is then converted to parallel data and is latched for constant control of the various circuits U4 and U6 are used for TTL serial to parallel conversion U24 and U25 are used for ECL serial to parallel conversion TTL signals are converted to ECL by U26a U26b and U26d 07 is a high power buffer which drives the various relays throughout the board The timing capacitors are switched and out by U5 6 5 CALIBRAT
39. ae Seb eg eon al eae dece edm me rg 6 6 Phase Locking Circuit 6 6 Counter Conditioning Circuit 6 6 Output Amplifier Board 6 6 Pulse Shaper GIrGul UTR eC qx eel 6 6 Waveform Selector Circuit 6 7 Amplitude Modulation Circuit 6 7 Step Attenuator Circuit 6 7 Power Amplifier Circuit ln 6 7 Offset and Amplitude Sensing Circuit 6 7 Rise Time Sensing Circuit model 8551 6 7 Boardi 2 2 ee xm wor fem ha m NOE E X 8 o5 A s 6 8 Power Supply 6 8 Reference Distribution Circuit 6 8 Reference DAC s Circuit 6 8 Pulse Generator Board model 8551 6 8 Monostable Multivibrator Circuit 6 8 Pulse Width Current Generator Circuit 6 9 Ramp Generator Circuit 6 9 Transition Times Generator Circuit 6 9 Transition Times Current Generator 6 9 Auxiliary Circus RE X des 6 9 Contents v
40. as follows CONTROL POSITION Frequency 10 00 KHz Trigger Mode GATED 2 Depress a few times the MANUAL push button and verify that you get a gated sinewave waveform on the oscilloscope every time that the MANUAL push button is depressed Remove 8550 output from the oscilloscope for the next test 5 9 10 3 Manual Burst 1 Set 8550 as follows CONTROL POSITION Frequency 10 00 KHz Trigger Mode Burst Int Trig Per 1 ms 2 Set 8550 to Internal Burst mode by depressing 2nd and INT TRG push buttons in sequence 3 Set oscilloscope and verify on the oscilloscope that 8550 outputs repetitive bursts of two complete output waveforms 5 9 10 Manual Trig Gate Burst Characteristics Specifications MANUAL push button simulates ex ternal stimulant Equipment Oscilloscope universal counter timer 5 9 10 1 Manual Trigger 1 Set 8550 as follows CONTROL POSITION 5 6 Maintenance And Performance Tests Page CONTROL POSITION Frequency 10 00 MHz Trigger Mode BURST Burst 4000 2 Connect 8550 output to the universal counter timer input Set counter to Totaling measurement mode Reset counter 3 Depress the MANUAL push button once and verify that counter reading is exactly 4000 counts 5 9 11 Trigger Start Phase Offset Accuracy Specifications 90 to 90 3 to 500 KHz Equipment Oscilloscope 1 Set 8550 as follows CONTROL POSITION Amplitude 1 2 V Trigger Mode TRIG D TRIG ON Int Tr
41. board The circuits that are discussed here are the monostable multivibrator circuit the pulse width cur rent generator circuit the ramp generator circuit the transition times generator circuit the transition times current generator circuit and the auxiliary circuits Complete and detailed schematics of this board are located at the end of this manual 6 8 1 Monostable Multivibrator Circuit The Monostable Multivibrator generates a pulse with a certain width every time that a trigger input signal is received This circuit is made of D flip flop U18a U18b timing capacitors ramp buffer Q28 comparator U20 and their associated components In the stable state the output of U18b pin 15 is set at about 0 8 V equal to the voltage level on the selected timing capacitor This voltage is applied through an impedance converter and buffer Q28 to the inverting input of U20 The non inverting input of U20 is kept at a lower voltage level by a dc control circuit The resulting voltage level at the output of the comparator output pin 5 is 0 ECL level 1 8 V The timing capacitor discharging current flows from Q36 through the output of U18b pin 15 The triggering signal for the multivibrator is re ceived from the VCO board through J2 pin 12 and is routed to the clock input of U18a U18a together with the delay circuit which is made of R70 and C23 generate narrow positive going pulses every time that a positive transition from the VC
42. case for improved RFI and EMI shielding It is housed in a size to fit half rack enclosures Regardless of its small size Model 8550 offers many features and functions such as enhanced accuracy eight different linear and logarithmic sweep modes automatic phase Section 1 lock loop pulse and ramp waveforms with transition time control Model 8551 only counted burst internal trigger generator full implementation of the new IEEE 488 2 standard and more But most of all Model 8550 guarantees high quality waveforms throughout the specified frequency range amplitude span and operating temperature Model 8550 generates waveforms within a fre quency range from 10mHz to 50MHz and an am plitude span from 10mV to 32Vp p Such broad coverage warrants a variety of complex applications Rapid repeatable testing every time is assured by a non volatile memory Up to 30 front panel set ups can be stored and recalled for later use ensuring exact duplication of previous tests Its performance programmability and economy make it equally at home in every laboratory For improved output accuracy Model 8550 em ploys a built in counter This counter is incorporated in an internal loop which constantly monitors the output frequency Even the slightest deviation from the programmed frequency is detected and corrected by the microprocessor circuit Model 8550 features self calibration and self di agnostic functions that can be operated a
43. circuit on the cali bration board Check the PLL filter U30 U32 and their associated components on the calibra tion board FAIL 2 Check the U3d U4c U2a U38c U34a and their associated components on the calibration board Check the counter circuit on the C P U board FAIL 3 Check the components as in FAIL 2 7 5 5 Trigger Phase Offset Calibration Failures Failures in the trigger phase offset circuits are indi cated by a blinking TRIG PHASE indicator with an associated displayed readout In general trigger phase offset failures may generate as a result of faults in the calibration and the V C O boards The following is a list of possible trigger phase offset calibration failures Possible solutions to remove the source of these errors are suggested FAIL 1 Check the trigger input circuit U26 and its associated components Also check the trigger phase offset control U2b U3a U3d Q1 and their associated components on the calibration board Check the trigger logic circuit U23 U16 U21 and their associated components on the V C O board FAIL 2 Check the trigger phase offset control cir cuit U2b U3a U3d Q1 and their asso ciated components on the calibration board 7 5 6 Counted Burst Calibration Failures Failures in the counted burst circuit is indicated by a blinking TRIG BUR indicator with an associated displayed readout In general counted burst failures may generate as a result of faults in the
44. cycle Model 8551 only VLEE Display leading edge transition time Model 8551 only VTRE Display trailing edge transition time VRPT Display internal trigger generator period VBUR Display counted burst VTLV Display trigger level VTPH Display trigger phase offset Model 8550 only VDCO Display dc output level Model 8550 only VSTP Display logarithmic sweep stop Model 8550 only VSWT Display sweep time Model 8550 only VMRK Display logarithmic sweep marker Model 8550 only VSSN Display linear sweep stop Model 8550 only VMKN Display linear sweep marker Suffix Data is optional 4 14 GPIB Operation Table 4 5 Device Dependent Command Summary continued Mode RESPONSE DATA QUERY Model 8551 Model 8551 Model 8551 Model 8551 Model 8551 annann xw YH YY WH COMMON COMMANDS RESPONSE MESSAGE FORMAT Program Header and Data FRQ AMP OFS PLL PER WID DTY LEE TRE RPT BUR TLV TPH DCO STP SWT MRK SSN MKN ERR STT FSA FSB FSC X0 x1 CLS ESE RCL RST SRE TRG WAI Description Interrogate output frequency Interrogate output amplitude Interrogate output offset Interrogate phase lock offset Interrogate pulse period Interrogate pulse width Interrogate fixed duty cycle Interrogate leading edge transition time Interrogate trailing edge transition time Interrogate internal trig generator period Interrogate coun
45. damage to the input circuit 3 15 SELECTING AN OUTPUT WAVEFORM Selecting one of the available output waveforms is done by depressing one of the two push buttons in the OUTPUT section until the light behind the required Operating Instructions 3 15 waveform illuminates Model 8550 makes available six different waveforms through the OUTPUT con nector These waveforms are SINE WAVE POSITIVE SQUARE WAVE TRIANGLE NEGATIVE SQUARE WAVE DC SQUARE WAVE Model 8551 offers eight additional waveforms DC output function is omitted PULSE PULSE COMPLEMENT POSITIVE PULSE POSITIVE PULSE COMPLEMENT NEGATIVE PULSE NEGATIVE PULSE COMPLEMENT RAMP INVERTED RAMP Note that pulse complements are selected using the 2nd function selection procedure For more information on operating 2nd functions refer to paragraph 3 9 3 16 DISABLING THE OUTPUT The Model 8550 8551 features a stand by mode which disconnects the signal from the output con nectors The stand by function is especially useful in automatic test systems where the output is con stantly connected to the device under test and where modification of waveform parameters may endanger this device Note that after power up or software reset the output is disabled To resume normal operation simply depress one of the push button in the OUTPUT section The light behind the previously selected waveform illuminates indicating that the output signal in now connected to the output con
46. different set of commands to enable functions and report status The IEEE 488 2 treats the common commands and queries as device dependent commands For example TRG is sent over the bus to trigger the instrument Some common commands and queries however are optional most of them are mandatory The following set of command groups ensure that all devices communicate uniformly 1 System Data These commands are used to store or retrieve information such as device identifi cation descriptions and options It is possible to determine the manufacturer model and serial number of the device under remote control 2 Internal Operation These commands include such instrument operations as resetting self calibrat ing and self diagnostics of a GPIB device The device may respond to a calibration query to indicate that the calibration was carried out successfully and report any calibration errors that may have occurred The reset command sets the device dependent func tions to a known state and must not affect the state of the IEEE 488 interface the Service Request Enable register or Standard Event Status Enable register 3 Status and Event These commands control the status structure of the GPIB device and provide a means to read and enable events Included in these commands are Clear Event Status Enable Power on Status and Service Request Enable 4 Synchronization The operation of the devices within the system are synchroniz
47. error situation by exceeding the specified limits GPIB parameter programming errors are discussed in section 4 Front panel programming permits modification of parameters within the limits which are given in Table 3 2 Note that the modifier buttons x1 x10 and x100 can only modify a parameter within one range These buttons in con junction with the RANGE push button may cover the entire specified range 3 13 SELECTING AN OPERATING MODE MODEL 8550 Model 8550 may operate as a function generator as a sweep generator linear or logarithmic and as a phase locking generator Selecting one of the operating modes is done by depressing one of the OPERATING MODE 1 or U push buttons until the light behind the desired mode illuminates Description of the various modes which can be used Model 8550 is given in the following 3 13 1 Normal Function Generator Operating Mode Model 8550 Function generator operating mode is the normal operating conditions where the output waveform is symmetrical about its horizontal and vertical axis The normal operating mode also permits a vertical offset of its output waveform The generator is placed in its normal operating mode when the light behind FUNC illuminates Triggered operation and externally controlled modes such as VCO FM and AM may operate in conjunction with the normal function gen erator operating mode 3 13 2 Linear Logarithmic Sweep Operating Mode Model 8550 Placi
48. essor capable of directly addressing up to 64K bytes of program memory ROM and up to another 2K bytes of data memory RAM The microprocessor works with a 12 MHz clock which is divided by U6 to provide clocks for the various sections of the instrument Software for the CPU is contained in one EPROM U8 containing 64K bytes of memory Theory of Operation 6 1 Figure 6 1 Model 8550 8551 Simplified Block Diagram 7301 anwo t 6 2 Theory of Operation space Temporary storage is provided by RAM U9 which can store up to 2K bytes of information 6 3 1 Display and Keyboard Interface Interfacing between the CPU the keyboard and the display is performed by the Keyboard Display interface U2 The information for the seven segment LEDs is sent through buffer U1 and limiting resistors RN1 U1 multiplex the digits and LED and drive the high current transistors Q1 through Q8 which in turn drive the anodes of the appropriate LED The sense lines SO S1 and S2 determine which of the front panel push button were depressed 6 3 2 Counter Circuit The counter circuit is employed in the Model 8550 8551 for the purpose of controlling the accuracy of the frequency at the output connector The counter circuit is composed of U10 U11 U13 and 14 The counter circuit counts the number of pulses from the VCO during a pre determined gate time interval The CPU then computes the relation bet
49. every time that a modifier push button is depressed Programming the Model 8550 with pulse ramp errors is possible and ex ecutable however when such errors are detected the ERROR light starts blinking indicating that the signal at the output connector may emerge with other parameters then those programmed The light error blinks until the error conditions are removed Pulse ramp error summary is given in Paragraph 4 14 4 Pulse Ramp errors may occur under one or more of the following conditions 1 The programmed pulse ramp WIDTH parameter is greater than the selected period 2 Model 8551 is placed in linear transition time and one of the programmed transitions is greater than the selected pulse width 3 Model 8551 is placed in internal triggered mode and the programmed pulse ramp width is greater than the selected internal trigger period 4 The programmed ramp width is outside the limit of 5 00us 5 The programmed pulse width is outside the specified limits 3 8 4 IEEE 488 2 Errors In general whenever a GPIB programming attempts to put the model 8550 into an error condition the function generator responds in two ways First by displaying a front panel message and than if pro 3 8 Operating Instructions grammed so by raising an SRQ flag in its Status Byte Register Using the serial poll command the controller may then address the generator and request its status byte The generator incorporates a number of dis
50. failures also pro duce error bits in the special calibration failure reg isters which are accessible through GPIB commands and queries Front panel calibration and self diagnostics aspects are discussed in paragraphs 3 10 and 3 11 GPIB aspects of calibration failure status registers are discussed in paragraph 4 14 3 The self calibration sequence may be initiated at any time It is however recommended that such sequence be initiated under certain conditions which are listed in paragraph 3 10 Troubleshooting procedure should also be initiated whenever the generator fails to perform either com pletely or partially It is also required to troubleshoot Model 8550 8551 whenever the instrument fails to fully comply with its published specifications In such cases it is first recommended that self calibration procedure be initiated If this procedure has been completed without encountering an error and if prob lem still remains it is then necessary to remove the top and bottom covers and troubleshoot the generator using some other means Note that the information given in the following do not intend to replace full scale troubleshooting but merely to direct the service engineer to the area were the source of the trouble is located The self diagnostics failure list is automatically generated after a self calibration procedure To initiate the self calibration procedure depress the two front panel AUTOCAL push buttons simultaneously
51. in its PLL operating mode for automatic detection of the frequency of the external reference The frequency counter reading is made available to the user and can measure external frequencies from 10Hz to over 60MHz Frequency reading is given with fixed resolution of 4 digits Decimal point and exponent are displayed automatically To use Model 8550 as a frequency counter proceed as follows 1 Depress the POWER switch once to turn the power on 2 Depress the operating mode push buttons until the light behind PLL illuminates 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Remove any BNC cable from front panel connectors 5 Depress the FUNC push button in the MAIN PARAMETERS group until the light behind FREQ illuminates observe the programmed frequency set ting 5 Connect a BNC cable from the reference source to the front panel REF INPUT connector 6 Observe that the displayed reading is modified to read the frequency of the external frequency and that the decimal point blinks at a constant rate indicating that the display reads the frequency of the external signal 7 Remove the BNC cable from the REF input connector and observe that the decimal point stopped blinking and that the display resumes its normal programmed frequency parameter 3 13A SELECTING AN OPERATING MODE MODEL 8551 Model 8551 may operate as a normal function generator as a variable pulse width pulse generato
52. modification through front panel programming The offset parameter is controlled by a digital to analog converter U24 operational amplifiers U23 and U29 analog switch U25a and their associated com ponents The digital to analog converter receives its digital commands from serial to parallel converters U27 and U28 The frequency parameter is controlled by two digital to analog converters U6 and U14 operational amplifiers U9 U10 and U13 by transistor Q2 and their associated components The current through the collector of Q2 controls the current generator in the VCO board Below 1 MHz the amplitude of the triangle which is generated in the VCO circuit is controlled by an operational amplifier U22 and resistors R38 and R39 The triangle is set to operate within 1 2 V and 1 2 V amplitude limits In higher output frequencies above the range of 1 MHz due to internal circuit delays this triangle amplitude presents tendencies to increase Whitin the output frequency range of 1 MHz to 10 MHz a digital to analog converter U16 compensates this effect by injecting correcting current at the input to U22 through an analog switch U25b and R42 Within the range of 10 MHz to 50 MHz the correcting current is generated by the digital to Theory of Operation 6 5 analog converter U16 and applied through an analog switch U25c R43 and thermistor T1 The Calibration board also contains some circuits pertaining to the sweep outputs The s
53. modify how the NRf is interpreted by the device For an example to program the model 8550 for a frequency output of 10 7 MHz the following pro gram message unit options may be used FRQ 10 700000 or FRQ 10 7MAHZ or 10 7E 6 or FRQ 10 7E6HZ etc Command program header and suffix program data and optional multipliers summary is given in the following FRQ MHZ HZ KHZ MAHZ Program frequency parameter AMP MV V Program amplitude parameter OFS MV V Program offset parameter DEG Program phase lock offset parameter 4 18 GPIB Operation PER NS US MS S Program pulse period parameter model 8551 only WID NS US MS S Program pulse width parameter model 8551 only DTY PCT Program fixed duty cycle parameter model 8551 only LEE NS US MS S Program leading edge transition time parameter model 8551 only TRE NS US MS S Program trailing edge transition time parameter model 8551 only RPT NS US MS S Program internal trigger generator period parameter BUR Program counted burst parameter TLV MV V Program trigger level parameter TPH DEG Program trigger phase offset parameter DCO MV V Program dc output level parameter model 8550 only STP MHZ HZ KHZ MAHZ Program logarithmic sweep stop parameter model 8550 only SWT NS US MS S Program sweep time parameter model 8550 only MRK MHZ HZ K
54. must be rectified before continuing operation 5 4 DISASSEMBLY INSTRUCTIONS If it is necessary to troubleshoot the instrument or replace a component use the following disassembly procedure to remove the top cover POWER LINE RATING FUSE TYPE 90 125V 1 0A 250V 5x20mm slo blo 195 250V 0 5A 250V 5x20mm slo blo Table 5 1 Line Fuse Selection Maintenance And Performance Tests Page 5 1 1 Remove the two screws that secure the top cover to the rear panel 2 Grasp the top cover at the rear and carefully lift it off the instrument When the tabs at the front of the cover clear the front panel the cover may be pulled completely clear 3 When replacing the top cover reverse the above procedure be sure to install the tabs at the front panel before completely installing the cover 5 5 SPECIAL HANDLING OF STATIC SENSITIVE DEVICES MOS devices are designed to operate at a very high impedance levels for low power consumption As a result any normal static charge that builds up on your person or clothing may be sufficient to destroy these devices if they are not handled properly When handling such devices use precautions which are described in the following to avoid damaging them 1 The MOS ICs should be transported and handled only in containers specially designed to prevent static build up Typically these parts will be received in static protected containers of plastic or foam Keep these devices in their o
55. output amplitude parameter OFS Interrogate output offset parameter PLL Interrogate phase lock offset parameter PER Interrogate pulse period parameter model 8551 only WID Interrogate pulse width parameter model 8551 only DTY Interrogate duty cycle dat string model 8551 only LEE Interrogate leading edge transition time parameter model 8551 only TRE Interrogate trailing edge transition time parameter model 8551 only RPT Interrogate internal trigger generator period parameter BUR Interrogate counted burst parameter TLV Interrogate trigger level parameter TPH Interrogate trigger phase offset parameter DCO Interrogate dc output level parameter model 8550 only STP Interrogate logarithmic sweep parameter model 8550 only SWT Interrogate sweep time parameter model 8550 only MRK Interrogate logarithmic sweep marker pa rameter model 8550 only SSN Interrogate linear sweep stop parameter model 8550 only Interrogate linear sweep marker parameter model 8550 only EER Interrogate pulse ramp error model 8551 only STT Interrogate machine status FSA Interrogate calibration failure status byte A FSB Interrogate calibration failure status byte B FSC Interrogate calibration failure status byte C For example model 8550 is asked to return frequency amplitude and offset parameters in a single Response Message Command FRQ AMP Response FRQ 1 000E 3 AMP 1 0
56. that it takes for completing one sweep cycle Sweep time is different for logarithmic sweep mode where the specified value is that required for sweeping one decade The generator may be 3 2 Operating Instructions set to sweep over 10 decades In that case the sweep time should be multiplied by ten Decade size ranges from 1000 to 9999 counts or 100 1 if settings other than full and minimum scales are required If only part of the decade is being swept the sweep time is reduced proportionally The sweep time pa rameter may be programmed within the range of 10ms to 999s Preset value is set to 1 00s MARK Specifies the frequency of which the sweep marker changes its voltage level at the marker output connector The marker output is only active when the function generator is set to operate with one of its built in sweep modes The sweep marker parameter may be programmed within the same range as the frequency stop parameter Preset value is set in both linear and logarithmic modes to 5 000KHz 3 PHASE OFFSET PLL The Model 8550 output may be locked to an external signal The operator may then introduce a phase offset between the leading edge of the external signal and the leading edge of the signal at the output connector The phase offset is pro grammed with the PLL parameter The phase offset parameter may be programmed within the range of 180 Preset value is set to 0 TRIG The TRIG parameter inserts a phase offset
57. the RL function 4 4 GPIB Operation Table 4 1 Model 8550 Interface Function Codes CODE INTERFACE FUNCTION SH1 Source Handshake Function AH1 Acceptor Handshake Capabilities T6 Talker basic talker serial poll unaddressed to talk on LAG L4 Listener basic listener unaddressed to listen on TAG SR1 Service request capability RL1 Remote Local capability PP2 Parallel Poll capability DC1 Device Clear capability DT1 Device Trigger capability CO No controller capability E1 Open collector bus drivers TEO No Extended Talker capabilities LEO No Extended Listener capabilities PP parallel Poll Function The ability of the Model 8550 to respond to a parallel poll request from the controller is provided by the PP function DC Device Clear Function The ability for the Model 8550 to be cleared initialized is provided by the DC function DT Device Trigger Function The ability of the Model 8550 to have its output triggered is provided by the DT function C controller Function The Model 8550 does not have a controller function TE Extended Talker Capabilities The Model 8550 does not have extended talker capabilities LE Extended Listener Function The Model 8550 does not have extended listener function 4 5 SOFTWARE CONSIDERATIONS The most sophisticated computer in the world would be useless without the necessary software This basic requirement is also true of the IEEE 488
58. the following table apply under the following conditions main signal output terminated into 500 within 5 24 hours of last internal calibration and after 30 minutes of warm up time within a temperature range of 0 to 50 Table 1 1 Model 8550 8551 Specifications WAVEFORMS FREQUENCY CHARACTERISTICS Range Resolution Accuracy Continuous Mode VCO and Interrupted Modes Jitter WAVEFORM CHARACTERISTICS Sine Wave Total Harmonic Distortion Harmonic signals below the carrier level Flatness Triangle Linearity 1096 to 9096 of Flatness Square Wave Pulse Rise Fall time Aberration SYNC Pulse Output Level Rise Fall time Aberrations OUTPUT CHARACTERISTICS Output Stand by Impedance Output Level Resolution Accuracy 1 KHz Sine Triangle Square Positive Pulse Negative Pulse Ramp Model 8551 DC Model 8550 10 00mHz to 50 00MHz 4 digits 3 of reading from 10mHz to 999 9mHz 0 1 from 1 000 2 to 50 00MHz 3 of reading to 50 00MHz 0 195 50 5 196 10 00mHz to 100 0KHz gt 40dB 100KHz 2 000MHz gt 21dB 2 000MHz 50 00MHz 1 10 00mHz to 999 9KHz i296 1 000MHz to 9 999MHz 1596 10 00MHz to 50 00MHz amplitude 196 10 00mHz to 5 000MHz 396 5 000MHz to 20 00MHz 896 20 00MHz to 50 00MHz i396 10 00m Hz to 999 9KHz 5 1 000MHz to 9 999MHz 2596 10 00MHz to 50 00MHz 6ns 1096
59. to turn the power on 2 Select the required output waveform and set up the parameters to the required characteristics 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Depress the TRIGGER MODE push button until the light behind GATED illuminates 5 Connect a BNC cable from the external stimulant to the front panel TRIG REF INPUT connector Make sure to observe external signal limits to avoid damage to the input circuit 6 When done with the gated operation remove the BNC cable from the input connector and select the normal continuous mode 3 17 1 3 Counted Burst Mode When set to operate in counted burst mode each positive going transition at the TRIG REF INPUT connector generates a train of waveforms at the OUTPUT connector The number of generated wave forms are programmable within the range of 1 to 4000 The first waveform at the output connector is automatically synchronized with the external transition To generate a counted burst using an external source proceed as follows 1 Depress the POWER switch once to turn the power on 2 Select the required output waveform and set up the parameters to the required characteristics 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Depress the TRIG push button in the MAIN PARAMETERS group until the light behind BUR illuminates Modify the burst parameter to the required count 5 Depress the TRIGGER M
60. 0 ms 52 0 ms 1 500 s 500 ms 480 ms 520 ms Maintenance And Performance Tests Page 5 9 4 Disconnect 8551 output from counter input and connect to oscilloscope input Set oscilloscope input impedance to 509 5 Set 8551 Period to 100 0 ns and Pulse Width to 10 0 ns 6 Verify that oscilloscope reading is between 8 ns to 12 ns 5 9 17 Rise Fall Time Accuracy model 8551 Accuracy Specifications 5 2 ns from 8 ns to 99 9 ms 4 2 ns above 99 ns Equipment Counter Oscilloscope 500 feedthrough termination 1 Set 8551 as follows CONTROL POSITION Operating Mode Pulse Output Squarewave Amplitude 4 00 V Transitions Linear 2 Set counter to Rise Fall Time measurement Con nect 8551 output to counter input through the 500 feedthrough termination 3 Set 8551 Period Pulse Width and Lead Trail Transition times and verify counter reading as given in Table 5 3 5 Change 8551 Period setting to 100 0 ns Pulse width setting to 50 0 ns and Lead and Trail setting to 10 0 ns 6 Verify that oscilloscope reading is between 9 0 ns to 11 0 ns 5 9 18 PWM Characteristics model 8551 Specifications 0 to 5 V 20 produces gt 10 pulse width change from DC to 700 KHz Equipment Counter DMM dc power supply 1 Set 8551 as follows CONTROL POSITION MOD Mode PWM Operating Mode Pulse Period 1 500 ms Pulse Width 500 us Output Squarewave 2 Connect 8551 output to counter input Set counter and note pul
61. 02 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 74902 Parts List 8 13 Table 8 2 Model 8551 Parts List continued OP 1 2 3 4 1 1 1 3 1 1 1 1 1 3 1 2 1 Reference Designation R8 R19 R20 R34 R95 R80 R26 R78 R79 R142 R92 R144 R101 R21 R22 RN1 U1 U2 U28 U3 U17 U18 U4 U6 U24 U25 U9 U11 U12 010 013 014 015 029 016 U19 U20 U22 U21 U23 U27 U26 8 14 Parts List Description and Commercial Part Number 1 1K 196 1 4W 1 13K 196 1 8W 1 87K 196 1 8W 2 K 196 1 4W 2 49K 196 1 4W 4 99K 196 1 4W 6 81K 1 1 4W 7 32K 1 1 8W 9 09K 1 1 4W 10K 1 1 4W 20K 1 1 4W 51 1K 1 1 4W 100K 1 1 4W 1M 1 1 4W CHIP 5 33 RES VAR 20K 3386W 1 203 RES VAR 2K 3386W 1 202 RES VAR 1K3386W 5X1K CSCO6A 01 102J OP TLO81CP ANALOG SWITCH DG411DJ OP AMP 8 BIT SHIFT REGISTER CD4094BCN QUAD OP AMP LM324N BUFFER ULN2004N OP AMP LM741C TRANS ARRAY CA3127E HA3 5033 5 MAX9690CPA DUAL OP AMP TLO82CP OP AMP OP 200GP ECL FLIP FLOP MC10H131P ECL MC10HO16P ECL OR NOR GATE MC10H105P ECL NOR MC10102P QUAD COMP LM339N Tabor Part Number 0104 11010 0102 1131A 0102 1871A 0105 20010 0104 24910
62. 0E 0 Table 4 7 shows the general lt Response Mes sage gt format for each of the above commands Default values are shown These defaults are gen erated after an SDC or DCL commands 4 12 2 Common Queries As discussed in previous paragraphs most instruments and devices in an ATE system use similar commands which perform identical functions to avoids the prob lem which devices from various manufacturers used a different set of commands to enable functions and report status Some common commands and queries however are optional most of them are mandatory The following set of common queries are utilized in the model 8550 optional common queries that are not included in the model 8550 command set will not be discussed here CAL Calibration Query causes a device to perform an internal self calibration and generate a response that indicated whether or not the device completed the self calibration without error The cali bration errors are stored in an internal 8 bit register which is not accessible by device dependent or com mon queries Each bit in this register represents an error in a different block within the model 8550 The generator responds to this query with a number in the range of O to 32767 The binary equivalent of the number represents the detected error in the calibration process For example if a value of 32 indicates a calibration failure in the pulse width circuit Similarly A value of 24 indicates
63. 1 NR2 or NR3 format and Response Message Terminator CAL CLS ESE ESR IDN OPC OPC RST SAV SRE SRE STB TRG TST WAI ESR STB and RQS read by Serial Poll Selectable NL END or combination of both Front panel programming Address stored in a non volatile memory 4 digits 7 segment LED s 0 5 high 115 230Vac Optional 100V available 50 to 400Hz 100VA max Stores 30 complete sets of front panel set ups 3 5 x 8 3 x 15 4 x W x L 3 5 x 19 H x W Approximately 12Lbs 0 to 50 C Within x5 C and 24 hours of last internal calibration 40 C to 70 C 855096 R H MIL T 28800D EN61010 IEC1010 1 UL 1224 EN50081 1 EN55022 EN50082 1 IEC801 2 IEC801 3 IEC801 4 Operates at a vibration level of 0 013 in from 5 to 55Hz 2g at 55Hz Non operating 40g 9ms half sine pulse General Information 1 7 This page intentionally left blank 1 8 General Information Preparation 2 1 INTRODUCTION This section contains information and instructions necessary for the installation and shipping of the Model 8550 and Model 8551 Details are provided for initial inspection voltage selection primary power frequency power connection grounding safety re quirements installation information and re packing instructions for storage or shipment 2 2 UNPACKING AND INITIAL INSPECTION Unpacking and handling of the counter requires o
64. 1 of full scale from 1 000 Hz to 50 00 MHz full scale reading is 5000 counts Equipment Counter 1 Set 8550 as follows CONTROL POSITION Output Squarewave 2 Set counter to frequency measurement 3 Connect 8550 output to counter input Set 8550 frequency and verify counter frequency reading as follows 8550 SETTING COUNTER READING 9 999 Hz 9 989 Hz 10 00 Hz 99 99 Hz 99 89 Hz 100 1 Hz 999 9 Hz 998 9 Hz 1 001 KHz 9 999 KHz 9 989 KHz 10 01 KHz 99 99 KHz 99 89 KHz 100 1 KHz 999 9 KHz 998 9 KHz 1 001 MHz 9 999 MHz 9 989 MHz 10 01 MHz 10 00 MHz 9 999 MHz 10 01 MHz 50 00 MHz 49 95 MHz 50 05 MHz 5 9 3 Amplitude Accuracy Accuracy specifications 1KHz 4 of reading from 10 mV to 16 0 V Equipment DMM 500 feedthrough termination 1 Set 8550 as follows CONTROL POSITION Display Modify AMPL 2 Set DMM to ACV measurements RMS 3 Connect 8550 output to DMM input Terminate the output with a 50Q feedthrough termination Set amplitude and output waveform and verify DMM reading as follows 8550 SETTING DMM READING Sinewave 16 0 V 5 431 V 5 883 V Triangle 16 0 V 4 439 V 4 809 V Square 16 0 V 7 680 V 8 320 V Sinewave 9 99 V 3 391 V 3 673 V Sinewave 3 00 V 1 018 V 1 103 V Sinewave 999mV 339 1mV 367 3mV Sinewave 99 9mV 33 91mV 36 73mV If model 8551 is tested modify front panel settings as follows and proceed with the next two tests 5 4 Maintenance And Performance Tests P
65. 1 to 855096 1 6 General Information Table 1 1 Model 8550 8551 Specifications continued LEAD TRAIL TIME CONTROL Model 8551 only Range In Range Span Resolution Accuracy Linearity 8ns to 99 9ms 1096 to 9096 of amplitude in 6 overlapping ranges Leading and trailing edges may be independently programmed within a common range 125 1 3 digits of programmed value when both transitions are in the first 10 1 portion of their transition time range decreasing to 2 digits at 100 1 5 2ns to 99ns 4 2 lt above 99ns 3 for transitions gt 100ns GPIB INTERFACE IEEE 488 2 Interface Functions Programmable controls Subsets Program Message Format Response Message Format Common Commands and Queries Status Reporting String Termination Address Selection GENERAL Display Power Stored Set ups Dimensions Rack Mount Dimensions Weight Operating Temperature Specified Accuracy Storage Temperature Humidity range Safety Designed to EMC Vibration Shock Complies with IEEE488 2 including queries and common commands All front panel controls except POWER switch SH1 AH1 T6 TEO L4 LEO SR1 RL1 PP2 DC1 DT1 CO Program Message Header Program Data floating point and or suffix program data Program Message Terminator Characters lower or upper case Variable length response format consisting of Response Header Response Data NR
66. 1 201 RELAY RY 05WK R10 RELA RELA Y DIP 1A 5V HE721A 0100 Y DIP 2A 5V HE722A 0100 BEAD Ferrite CERAMAG24 57 1355 TSTR TSTR TSTR TSTR TSTR TSTR TSTR TSTR TSTR TSTR RES RES RES RES RES J 109 J 309 PN3904 PN3906 MPS3640 MPS3646 2N3960 PN5771 PN5087 2N5179 COMP 10 5 1 8W BB1005 COMP 22 5 1 8W BB2205 COMP 33 5 1 8W BB3305 COMP 33 5 1 4W COMP 39 5 1 8W BB3905 ZENER 1N749A SELECTED 1522 0105A 1510 04310 1533 01070 1540 0106B 0300 00400 0300 20900 0300 20200 0300 20500 0300 20700 0300 20000 0300 10300 3000 30520 3000 16000 0900 00700 0900 01100 0900 01200 4200 00000 0400 02500 0400 02510 0400 01200 0400 01340 0400 00100 0400 00200 0400 20000 0400 00750 0400 01900 0400 00700 0102 01000 0102 02200 0102 03300 0100 03300 0102 03900 Vendor Code 96095 31433 96095 59821 59821 59821 59821 14655 59821 31433 14936 23338 23338 14936 14936 14936 54893 27264 74970 55101 12617 12617 59821 17856 17856 04713 04713 04713 04713 04713 04713 04713 04713 74902 74902 74902 74902 74902 Table 8 2 Model 8551 Parts List continued 4 1 2 1 1 2 1 2 1 2 3 1 1 2 2 2 2 1 3 2 4 1 1 3 1 2 1 2 3 3 Reference Designation R132 R28 R137 R52 R73 R74 R87 R93 R94 R118 R85 R102 R105 R120 R133 R134 R138 R136 R14 R15 R56 R60 R61 R65 R67 R108 R109 R104 R82 R110 R111 R113 R116 R117 R122 1
67. 10 04713 Q3 Q4 Q9 Q10 TSTR PN3904 0400 01200 04713 Q5 Q8 TSTR 2N5179 0400 00700 04713 A Ah aama R61 R76 RES COMP 33 5 1 4W 0100 03300 74902 R65 R102 RES COMP 82 5 1 4W 0100 08200 74902 RES COMP 5 1 4W 0100 01010 74902 RES 5 1 4W 0100 01310 74902 RES 5 0100 02010 74902 RES 5 0100 03310 74902 R59 R60 R75 R77 RES 5 0100 04710 74902 R9 RES 5 0100 05110 74902 R50 R51 R83 R100 R109 RES 560 5 1 4W 0100 05610 74902 R79 R91 R92 R93 R94 R95 R78 R97 R98 RES COM 560 1 8W 5 0102 05610 74902 R11 R49 R66 R111 RES COMP 1K 5 1 4W 0100 01020 74902 R86 RES COMP 1 2K 5 1 4W 0100 01220 74902 R10 RES COMP 1 5K 5 1 4W 0100 01520 74902 R52 R62 R68 R85 R105 R108 RES COMP 1 8K 5 1 4W 0100 01820 74902 R56 R63 R67 R84 R104 R107 RES COMP 2 7K 5 1 4W 0100 02720 74902 R99 RES COMP 3 9K 5 1 4W 0100 03920 74902 R72 RES COMP 4 7K 5 1 4W 0100 04720 74902 R69 R71 RES COMP 6 8K 5 1 4W 0100 06820 74902 RES COMP 7 5K 1 8W 5 0102 07520 74902 RES COMP 8 2K 1 8W 5 0102 08220 74902 RES COMP 10K 1 8W 5 0102 01030 74902 gt O R29 R30 R33 R47 R96 R103 R110 COMP 10K 5 1 4W 0100 01030 74902 R31 COMP 100K 5 1 4W 0100 01040 74902 R32 COMP 1M 5 1 4W 0100 01050 74902 R36 9 76 1 1 4W 0104 9R760 74902 R57 R58 499 1 1 4W 0104 49900 74902 R17 825 1 1 4W 0104 82500 74902 R53 1K 1 1 4W 0104 10010 74902 R14 2K 1 1 4W 0104 20010 74902 R4 R7 R8 3 32K 1 1 4W 0104 33210 74902 R41 3 92K 1 1 4W 0104 39210 74902 R3
68. 12 1 Interrogate Parameter Data 4 22 4 12 2 Gommon Queries ble Ha a Rh om ae 4 23 4 12 3 Response Header 4 24 4 12 4 Response Message Terminator 2 4 24 4 13 Device Status Reporting 4 24 4 14 Status Byte Register 5 4 24 4 14 1 Reading the Status Byte Register 4 26 4 14 1 1 Reading with a Serial 4 26 4 14 1 2 Reading with the STB 4 26 4 14 1 3 Clearing the Status Byte Register 4 26 4 14 1 4 Service Request Enable Register 4 27 4 14 2 Standard Event Status Register ESR 4 27 4 14 2 1 Standard Event Status Enable Register 4 28 4 14 3 Calibration Failure Status Registers A B and 4 28 4 14 4 Pulse Ramp Error Status Register 4 29 4 14 5 Machine Status Register STT 4 30 4 15 Front Panel Error Messages 4 30 4 15 1 ILI Illegal Instruction Error 4 30 4 15 2 Illegal Parameter Error 4 30 4 16 GPIB Compatibility with HP Model 8116 4 30 SECTION
69. 2 bus which requires the use of handler routines as described in this paragraph Before a controller can be used with the IEEE 488 2 interface the user must make certain that appropriate handler software is present within the controller With the IBM PC com puter for example the GPIB interface card must be used with an additional software which contains the necessary handler software Other small computers that can be used as controllers have limited IEEE command capability The capabilities of some computers depends on the particular interface being used Often little software tricks are required to achieve the desired results From the preceding discussion the message is clear make sure the proper software is being used with the instrument Often the user may incorrectly suspect that a hardware problem is causing fault when it was the software that was causing the problem all along 4 6 HARDWARE CONSIDERATIONS Before the instrument can be used with the IEEE 488 bus it must be connected to the bus with a suitable connector Also the primary address must be properly programmed as described in this section 4 6 1 Typical Controlled Systems The IEEE 488 2 bus is a parallel interface system As a result adding more devices is simply a matter of using more cables to make the desired connections Because of this flexibility system complexity can range from simple to extremely complex The simplest possible controlled s
70. 24 R126 R128 130 R47 R48 R49 R50 R83 R106 R107 R140 R114 R103 R119 R148 R9 R10 R143 R11 R13 R23 R24 R51 R76 R54 R55 R58 R59 R62 R63 R70 R71 R77 R98 R100 R69 R42 R115 R127 R81 R45 R112 R139 R96 R97 R99 Description and Commercial Part Number RES COMP 47 5 1 4W RES COMP 51 5 1 8W RES COMP 82 5 1 4W RES COMP 100 5 1 8W RES COMP 100 5 1 4W RES COMP 130 5 1 4W RES COMP 220 5 1 4W RES COMP 270 5 1 8W RES COMP 300 5 1 4W RES COMP 510 1 8W 5 COMP 560 1 8W 5 COMP 1K 5 1 4W COMP 1 5K 5 1 4W COMP 1 8K 1 8W 5 1 8K 5 1 4W 2K 5 1 4W 2 2K 5 1 4W 2 7K 5 1 4W 3 3K 5 1 4W 10K 5 1 4W 33K 5 1 4W 49 9 1 1 4W 61 9 1 1 8W 100 1 1 4W 115 1 1 8W 127 1 1 1 8W 140 196 1 8W 154 196 1 8W 200 1 249 1 261 1 330 1 365 1 464 1 499 1 619 196 820 196 1 8W 825 196 1 8W 1K 196 1 4W 1K 196 1 8W 1K 0 196 1 4W BB1015 BB2715 Tabor Part Number 0100 04700 0102 05100 0100 08200 0102 01010 0100 01010 0100 01310 0100 02210 0102 02710 0100 03010 01020 0511 0102 05610 0100 01020 0100 01520 0102 01820 0100 01820 0100 02020 0100 02220 0100 02720 0100 03320 0100 01030 0100 03330 0104 49R90 0102 61R9A 0104 10000 0102 1150A 0102 1270A 0102 1400A 0102 1540A 0104 20000 0104 24900 0102 2610A 0102 03310 0104 36500 0104 46400 0102 4990A 0102 6190A 0102 08210 0102 8250A 0104 10010 0102 01020 0105 10010 Vendor Code 74902 749
71. 26 The 5 2 V linear supply is made of power transistor Q8 control amplifier U8a Q6 R26 R29 and overload protection Q7 and R27 6 7 2 Reference Distribution Circuit The reference distribution circuit is responsible for distributing the 2 5 V and the 5 V reference voltages throughout the instrument The 5 V reference is made of U2 and it is being distributed by the quad operational amplifier U1 and its associated compo nents 6 7 3 Reference DACSs Circuit The reference digital to analog converters generate reference voltages for correcting and compensating accuracy errors on the power amplifier and on the pulse width boards The digital to analog converter U4 operational amplifier U5 and their associated components generate an offset correcting voltage for the power amplifier circuit The digital to analog converter U12 operational amplifier U13 and their associated components generate an offset correcting voltage for the rise fall time circuit The D A converters 6 8 Theory of Operation receive their digital commands from serial to parallel converters U3 and 11 6 8 PULSE GENERATOR CIRCUIT Model 8551 The pulse generator board has the necessary circuits for generating pulses and ramps with variable pulse width and variable rise and fall times The pulse generator board is only installed on Model 8551 The following paragraphs contain descriptions of the various circuit that are available on the pulse generator
72. 4 82389 75915 62712 Parts List 8 15 This page intentionally left blank 8 16 Parts List Schematic Drawings Section 9 JS gt IO WHT SU ca Q4 2N3904 52 LINE VOLTAGE SELECT 8 66K 1 R20 4 1 HH SV 1 1 1 1 ca 100 25 YEL GRN Figure 9 1 Main Board Power Supply R F CURR GEN Figure 9 2 Main Board Inter connection Diagram CURRENT GEN CONTROL OUTPUT AMPLIFIER Figure 9 3 Main Board Components Location lt 3333 Kee Lea p appe ec 3 A 5 E lt 12 6 9 82 EN 010 21 lt 14 AMPL SENS 010 gt is E gt 4 lt OFS SENS 0519 4 gt lt 7 m alos ia 5 gt 4 2 4 6 17 1 3 5 di E 3 15 gt 1 48 2108 10 gt m gt umi NG TRIG NOAC 9 s C s lt 8 5543 cmm nee spe RED 2 L gt u 10 gt 12 STRAT 37 gt lt e 9 gt lt cm 1
73. 5 MAINTENANCE AND PERFORMANCE CHECKS 5 1 IMMrOGUCHIONY gus Basa de Ag te pee ink 5 1 5 2 Line Voltage Selection 5 1 5 3 Fuse Replacement 5 1 5 4 Disassembly Instructions 5 1 5 5 Special Handling Of Static Sensitive Devices 5 2 5 6 Gleanings e ea eee Dates DU dte m oe i eu ee 8 D eA 5 2 5 7 Repair and Replacement 5 2 5 8 Performance Checks 5 2 5 8 1 Environmental Conditions 5 2 5 8 2 Warm UpsPenod 5 3 5 8 3 Front Panel Settirigs x eor ek ee 5 3 5 8 4 Recommended Test Equipment 5 3 5 9 Performance Checks Procedure 5 3 5 9 1 Frequency Accuracy Gated Mode 5 3 5 9 2 Frequency Accuracy Continuous Mode 5 3 5 9 3 Amplitude Accuracy 5 4 5 9 4 DC Characteristics 5 4 5 9 5 Squarewave Characteristics 5 4 5 9 6 Sine Characteristics 5 5 5 9 7 Sine Flatness 55 RR UR M 5 5 5 9 8 External Trigger Gate
74. 50 8551 output to DMM input as shown in Figure 7 2 Set DMM to DCV measurements and 200 mV range 2 Adjust V C O board trimmer R21 until DMM reading on is 0 V 5 mV 7 3 3 Squarewave Response Adjustment Equipment DMM Oscilloscope 2465B 20 dB feedthrough attenuator 1 Change 8550 8551 Frequency setting to 1 000 MHz amplitude setting to 10 0 V and output wave form to squarewave 2 Connect 8550 8551 output through the 20dB at tenuator to the oscilloscope input as shown in Figure 7 3 Set oscilloscope input impedance to 500 DISTORTION ANALYZER r Figure 7 2 Connection Sine Level Adjustment MODEL 80 51 MAIN PARAMETERE 3 Set oscilloscope vertical gain and time base and adjust output board trimmer R84 for best pulse response 4 Change 8550 8551 amplitude setting to 1 00 V Set oscilloscope vertical gain and adjust output board trimmer R95 for best pulse response 5 Repeat steps 4 and 5 until best pulse response is obtained in both adjustments 6 Set DMM function to DCV and range to 2 V Connect DMM leads across R93 and verify that DMM reading is less than 1 5 V otherwise readjust R95 7 Change 8550 8551 frequency setting to 10 00 KHz amplitude setting to 10 0 V and output waveform to squarewave MODEL 80781 STATE PARAMETERS TRIGGER W JLS Sl 8 Set oscilloscope vertical gain and t
75. 540 01060 CER 1n SR155C102MAA 1500 01020 DIODE 1N4151 0300 00400 DIODE 1N5908 0300 90400 DIODE BRIDGE W005 0300 50100 DIODE BRIDGE KBU 6A 0300 50200 TSTR PN3904 0400 01200 TSTR PN3906 0400 01340 MJE3055A 0400 40400 TSTR MJE2955A 0400 40300 2 2 2 2 1 2 1 1 3 2 2 2 5 2 1 1 0 27 5 2W 0103 0R270 R6 R8 2 7 5 1 4W 0100 02R70 R3 R25 R26 100 596 1 4W 0100 01010 R23 R24 R28 R29 1K 596 1 4W 0100 01020 1 5K 5 1 4W 0100 01520 1 8K 5 1 4W 0100 01820 2 2K 5 1 4W 0100 02220 27K 5 1 4W 0100 02730 MF 4 64K 1 1 4W 0104 46410 R9 R14 R22 MF 4 99K 1 1 4W 0104 49910 COO Parts List 8 5 Table 8 2 Model 8551 Parts List continued Reference Designation R19 R10 R13 R17 R21 R30 R16 R18 R31 R32 43 AH AN Description and Commercial Part Number RES MF 8 66K 1 1 4W RES MF 10K 1 1 4W RES MF 20K 1 1 4W AUDIO TRANSDUCER AT 02 SW MAINS ON OFF NE18 2U EE QUAD OP AMP LM324 VOLTAGE REFERENCE REFO02CP 8 BIT SHIFT REGISTER CD4094B D A 10 BIT CONVERTER AD7533JN DUAL OP AMP LM1458N VOLTAGE REGULATOR MC7815CP VOLTAGE REGULATOR MC7915CP VOLTAGE REGULATOR MC7924CP VOLTAGE REGULATOR MC7824CP Output Amplifier Board Assembly C1 C4 C6 C7 C13 C17 C31 C35 C5 C9 C12 C20 C21 C26 C27 C57 C58 C60 C61 C8 C11 C15 C16 C18 C24 C25 034 C43 C51 C59 C62 C63 C14 C22 23 C28 C30 C32 C36 C38 40 C46 49 C52 C53 C54 C56 C29 C33 C37 C42 fp PY
76. 8 and Q9 and their associated components The operational amplifier U15 and resistors R68 R69 R91 R92 R97 R98 R104 and R105 closes this feedback around the power amplifier and com pensate for its offsets and dc gain errors R91 trimmer resistor adjusts the low frequency gain to be equal with the high frequency gain 6 6 6 Offset and Amplitude Sensing Circuit Offsets and amplitudes within the power amplifier are monitored by special circuits which are capable of measuring and adjusting both parameters to be within the required specifications The information from the sensing circuits is sent to the CPU board it is stored in special correction tables and is automatically applied to the output digital to analog converters for full accuracy operation The power amplifier offset if sensed by the comparator U16b and is transferred to the CPU through CR12 The amplitude is sensed by U16a This comparator circuit compares the peak amplitude against a precise dc reference of 2 5 V The result is converted to TTL and sent to the CPU board to be used in amplitude calibration tables 6 6 7 Rise Time Sensing Circuit Model 8551 Similar to the offset and amplitude sensing circuit the rise fall times are measured by a special circuit and converted to correcting information to be used by the CPU circuit The rise fall time sensing circuit is made of a dual comparator U17 and its associated components It coverts the rise time to an equi
77. 800 30000 VCO Board Assembly 6100 6220 C46 CAP CER 27P SR155C270KAA 1500 02700 CAP CER SR155C330KAA 1500 03300 CAP CER 100P SR155C100KAA 1500 01010 1 1 1 1 CAP CER SR155C102KAA 1500 01020 Parts List 8 11 Table 8 2 Model 8551 Parts List continued 1 1 1 1 1 1 6 6 3 2 2 1 1 2 2 2 2 1 1 1 4 E Reference Designation C27 C47 C48 C49 C13 14 C17 20 C28 29 C32 33 C37 38 040 C42 C43 45 C15 C23 C22 C21 C50 C24 C1 C2 C3 C4 C5 C6 C7 C10 C26 C34 C35 C51 CR1 CR3 CR5 CR8 CR9 CR11 CR12 Q8 11 016 Q21 Q27 Q15 Q17 Q18 Q33 Q4 Q6 Q7 Q23 Q24 Q25 Q31 Q32 Q2 Q3 Q5 Q28 Q13 Q14 Q19 Q20 Q22 Q26 Q29 Q30 R43 R44 R36 R86 R88 R89 R29 32 R35 R38 R40 R53 R57 R66 R68 R75 R84 R46 R72 R27 8 12 Parts List Description and Commercial Part Number CAP CAP CAP CAP CAP CAP CAP CAP CAP CAP CER 10n SR155C103KAA CHIP 0 14 0805 10475 CER 0 14 SR155C104ZAA POLY 4 7n 63V 2222 371 52472 POLY 47n 63V 2222 371 22473 Tabor Part Number 1500 01030 1560 01040 1500 01040 1522 04720 1522 04730 POLY 0 47u 63V 2222 371 12474 1522 04740 MYL 1p 100V 2222 344 21105 MICA 430P CD15ED431J03 ELEC 100 25V 2222 036 TANT 10u T350B106M025AS DIODE 1N4151 DIODE DIODE 1N753A 6 2V MATCHED DIODE ZENER 1N759A 12V DIODE ZENER 1N756A 8 2V DIODE ZENER 1N746A DIODE HOT CARRIER 5082 2835 CON CON FEMALE 2X8 90152 2216 RF MALE 131 170
78. C commands IEEE 488 2 RST common command 4 30 GPIB Operation Table 4 8 HP s Model 8116A Mode Parameter Messages MESSAGE Operating Modes Control Mode Haversine 90 Trigger Slope Waveforms Parameters MNEMONICS ASCII CODE DTY WID AMP OFS HIL ASCII CODE DELIMITER MZ Millihertz HZ Hertz KHZ Kilohertz MHZ Megahertz 96 NS Nanoseconds US Microseconds MS Milliseconds MV Millivolts V Volts MV Millivolts V Volts V Volts Description Select normal Select Trigger Select gate Not used in Model 8550 8551 Select internal sweep Opt 001 Select external sweep Opt 001 Select internal burst Opt 001 Select external burst Opt 001 Off Select FM Model 8550 only Select AM Select PWM Model 8551 only Select VCO Off On Off Not used in Model 8550 8 Positive slope Not used in Model 8550 8 Negative slope Not used in Model 8550 8 Off dc Model 8550 only Select sine Select triangle Select Square Select pulse Select positive pulse Select negative pulse Set frequency Set duty cycle Model 8551 only Set width Model 8551 only Set amplitude Set offset Set high level GPIB Operation 4 31 Table 4 8 HP s Model 8116 Mode Parameter Messages continued MESSAGE MNEMONICS ASCII CODE ASCII CODE DELIMITER Description Parameters Opt 001 BUR Set burst number RPT
79. CR2 CR3 CR6 CR8 CR10 CR1 1 CR12 CR13 CR14 CR15 CR16 CR17 m 8 6 Parts List CAP ELECTR 100u 25V 2222 036 CAP CER 1 SR155C102MAA CAP CHIP 0805 10475 CAP TANT 10u T350B106M025AS CAP CER 10n SR155C103KAA CAP CER 0 1u SR155C104ZAA CAP CER 6 8n SR155C682KAA CAP MICA 51P CD15ED510J03 CAP CER 33p SR155C330KAA CAP CER 470P SR155C471KAA CAP CER 3 3P SR155C3R3KAA CAP ELECTR 220u 50V 2222 036 SELECTED VALUE TYP 1 5p CAP CER 22P SR155C220KAA CAP CER 10P SR155C100KAA 1N747A 3 6V MATCHED 1N753A 6 2V MATCHED DIODE 1N4151 DIODE ZENER 1N751A 5 1V DIODE 1N752A 5 6V MATCHED DIODE ZENER 1N746A 3 3V Tabor Part Number 0104 86610 0104 10020 0104 20020 0900 01900 2000 10600 0500 53210 0530 00100 0540 01100 0560 00700 0500 56500 0500 52100 0500 52500 0500 52700 0500 52600 6100 6230 1533 01070 1500 01020 1560 01040 1540 0106B 1500 01030 1500 01040 1500 06820 1510 05100 1500 03300 1500 04710 1500 03R30 1535 02270 1500 02200 1500 01000 0300 20110 0300 20200 0300 00400 0300 20010 0300 20100 0300 20000 Vendor Code 74902 74902 74902 04597 23338 04713 24355 27014 1ES66 04713 04713 04713 04713 04713 Table 8 2 Model 8551 Parts List continued Reference Designation J1 J2 CON FEMALE 2X8 90152 2216 J3 J4 CON RF MALE131 1701 201 K1 K5 RELAY RY 05WK R10 L1 L6 L9 L15 L17 L18 BEAD Ferrite CERAMAG24 57 1355 Description and Tabor Commercial Par
80. CR3 CR5 K1 K3 K2 Q2 7 Q13 Q15 Q16 Q19 Q20 Q26 Q27 Q29 34 Q36 Q37 Q1 Q14 Q17 Q18 Q21 Q38 Q9 Q10 Q22 Q24 Q11 Q12 Q23 Q25 Q35 Q28 Q39 R27 R52 R53 R59 R63 R57 R61 R82 R93 R3 R4 R73 R86 R6 R15 18 R20 R31 R33 R55 R54 R69 R56 R58 CER 0 1 SR155C104ZAA CHIP 0 14 0805 10475 CAP TANT 10u 350 106 025 5 CAP CER 10n SR155C103MAA CAP MICA 910P CD15ED911J03 DIODE ZENER 1N746A 3 3V DIODE ZENER 1N747A 3 6V DIODE ZENER 1N753A 6 2V RELAY DIP 1A 5V HE721A 0100 RELAY DIP 1 5V HE721C 0100 PN3904 PN3906 MPS3640 BFY 90 2N5179 J 309 2N5912 22 5 1 4W 22 5 1 8W BB2205 33 5 1 4W 47 5 1 4W 82 5 1 4W 100 5 1 4W 130 5 1 4W 300 5 1 4W 510 5 1 4W 560 5 1 4W 1K 5 1 4W 2 2K 5 1 4W 2 7K 5 1 4W 3 3K 5 1 4W 1560 01040 1540 0106B 1500 01030 1510 09110 0300 20000 0300 20110 0300 20200 0900 01100 0900 01000 0400 01200 0400 01340 0400 00100 0400 00710 0400 00700 0400 02510 0400 40500 0100 02200 0102 02200 0100 03300 0100 04700 0100 08200 0100 01010 0100 01310 0100 03010 0100 05110 0100 05610 0100 01020 0100 02220 0100 02720 0100 03320 31433 31433 96095 14665 14936 14936 14936 12617 12617 Parts List 8 9 Table 8 2 Model 8551 Parts List continued Reference Description and Tabor Designation Commercial Part Number Part Number Vendor Code R26 COMP 4 7K 5 1 4W 0100 04720 74902 R1 R2 R19 R95 R97 R62 COMP 10K 5 1 4W 0100 01030 74902 R92 C
81. HZ MAHZ Program logarithmic sweep marker parameter model 8550 only SSN MHZ HZ KHZ MAHZ Program linear sweep stop parameter model 8550 only MKN MHZ HZ KHZ MAHZ Program linear sweep marker parameter model 8550 only The programming limits for each of the above parameters are listed in Table 3 2 After DCL or SDC the instrument defaults to its factory selected values Factory defaults are listed in Table 3 1 and 4 4 4 10 9 Display Parameter V The display parameter command controls what the Model 8550 places on the display The display parameter mode may be programmed by sending one of the following commands The numbers in parenthesis represent the value of V in the Machine Status String STT VFRQ Display output frequency parameter 01 VAMP Display output amplitude parameter 02 VOFS Display output offset parameter 03 VPLL Display phase lock offset parameter 04 VPER Display pulse period parameter model 8551 only 05 VWID Display pulse width parameter model 8551 only 06 VDTY Display fixed duty cycle parameter model 8551 only 07 VLEE Display leading edge transition time pa rameter model 8551 only 08 VTRE Display trailing edge transition time pa rameter model 8551 only 09 VRPT Display internal trigger generator period parameter VBUR Display counted burst parameter VTLV Display trigger level parameter VTPH Display trigger phase offset par
82. ING 45 40 7 49 3 90 84 3 95 7 150 145 2 154 8 459 310 7 319 39 90 264 8 275 7 150 205 2 214 8 6 Change 8550 PLL Phase Offset setting to 0 and trigger level setting to 0 0 V 7 Change counter function setting to Ratio A B Trigger level A and B settings to 0 00 V and Input Impedance A and B to 500 8 Connect test set up as described in Figure 5 2 9 Set synthesizer frequency and verify counter reading as follows CONTROL POSITION Operation Mode PLL 2019 SETTING COUNTER RATIO READING PPG 9 e 8550 COUNTER SYNC IN OUT B UT 9 J Figure 5 1 PLL Phase Offset Accuracy Check Maintenance And Performance Tests Page 5 7 Figure 5 2 Phase Lock Loop Operation Check SIGNAL GENERATOR ea S NG RF S 8550 COUNTER 6020 C Tue gt 5 A B 505 10 00000 2 1 0000000 20 00000 MHz 1 0000000 Teper Cope ge 30 00000 MHz 1 0000000 CONTROL POSITION 40 00000 MHz 1 0000000 MOD Mode AM 50 00000 MHz 1 0000000 Frequency 1 MHz 60 00000 MHz 1 0000000 Amplitude 4 V 2 Connect test set up a
83. ION BOARD The following paragraphs contain descriptions of the various circuit that are available on the Calibration board The circuits that are discussed here are the reference circuit the D A control circuit the Trigger input circuit the phase lock circuit and the counter conditioning circuit Complete and detailed schematics of this board are located at the end of this manual 6 5 1 Reference Circuit The reference circuit provides accurate and controlled voltage references for adjusting and calibrating the various parameters of the instrument The reference voltages are applied to the reference inputs of the various digital to analog converters The octal DAC U1 operational amplifiers U3 and U4 provide correcting voltages for the digital to analog converters Operational amplifiers U5 and U2 combine these correcting voltages with the 5 V and the 5 V references External controls are applied to U5 through U8 and the analog multiplexer switch U7 The output of U5b controls the reference input to the frequency D A converter the output of U5c controls the reference input to the amplitude D A converter the output of U5d controls the reference input to the pulse width D A converter the output of U2a controls the PLL phase offset and the output of U2b controls the trigger start phase offset 6 5 2 D A Parameter Control Circuit The following describes the control circuits for the various parameters that are available for
84. L 0 50V Model 8551 HIL and LOL CST M1 CTO TO W1 H0 A0 L0 CO DO BUR 0002 RPT 1 005 active LEE 10 0US TRE 10 0US TPH ODEG PLL ODEG 1 000KHZ DTY 50 WID 100US HIL 0 50V LOL 0 50V 4 32 GPIB Operation Table 4 8 HP s Model 8116 Mode Parameter Messages continued MESSAGE HP IB Universal Commands Interrogate Parameter Edge Control Error Reporting Response to IERR HP IB Status Byte Response to SPOLL Engineering notations can not MNEMONICS ASCII CODE ASCII CODE DELIMITER DC4 EOT BS EO NO ERROR WAVEFORM ERROR DUTY C ERROR WIDTH ERROR TIMING ERROR HANDLING ERROR LEVEL ERROR LIMIT ERROR Bit Bit Bit Bit Bit Bit Bit Bit Description Device clear DCL Selected device clear SDC Group execute trigger Interrogate error Interrogate frequency Interrogate duty cycle Interrogate width Interrogate high level Interrogate low level Interrogate amplitude Interrogate offset Interrogate burst Interrogate repetition rate Interrogate start frequency Interrogate stop frequency Interrogate marker frequency Interrogate sweep time Model 8551 only Not part of HP8116A commands set Fastest edge transitions Linear edge transitions No error detected Not used in Model 8550 8551 Not used in Model 8550 8551 Incompatible width and frequency setting Incompatible burst and frequency setting Programming parameters with values outside t
85. L 8 FAIL 9 7 5 2 Amplitude Calibration Failures Failures in the amplitude generation circuits are indicated by a blinking AMPL indicator with an 7 6 Adjustments and Troubleshooting associated displayed readout In general amplitude failures may generate as a result of faults in the V C O calibration pulse width and output amplifier boards The following is a list of possible amplitude calibration failures Possible solutions to remove the source of these errors are suggested If FAIL 1 through FAIL 5 were detected refer first to the theory of operation section and verify proper operation of the following circuits waveform Selector amplitude modulator step attenuator output amplifier and am plitude sensing circuits For other failures proceed with the following list FAIL 1 Check the sine generator and the sine amplifier circuits check relay K1 and buffer U10 on the V C O board FAIL 2 Check relay K1 and buffer U10 on the V C O board FAIL 3 Check ECL signal on U23 pin 2 on the V C O board Check ECL signal on U16 pin 2 on the V C O board Check the pulse shaper circuit on the output amplifier board FAIL 4 Check the pulse generator circuit on the pulse generator board Check the rise fall time generator on the pulse generator board Check the output amplifier circuit on the output amplifier board Check U19 U21 and their associated components on the pulse generator board FAIL 5 7 5 3 Offset Ca
86. L OP AMP LM1458N 0500 56500 04713 TRIPLE LINE REC 10216 0500 41100 04713 SINGLE OP TL081CP 0500 56700 04713 OP AMP LM 741C 0500 56310 04713 HIGH FREQ OP AMP CLC404AJP 0560 00300 62839 D A 10 BIT CONVERTER AD7533JN 0560 00700 1ES66 BUFFER 9668 L204 0500 11600 04713 SUPER GAIN OP AMP 7 0500 56330 04713 OP AMP LM393N 0500 53700 04713 ANALOG SWITCH NE521N 0500 54500 18324 po H 1 1 1 3 1 1 1 1 1 1 1 2 1 1 Pulse Generator Board Assembly 6100 6250 CAP 0 01 63V 2222 371 12103 1522 01030 CAP 47n 63V 2222 371 22473 1522 04730 CAP 470n 63V 2222 371 12474 1522 04740 CAP 4 7 63V 2222 368 22475 1522 04750 CAP 4 7 63 2222 371 52472 1522 04720 0 1u 63V 2222 371 12104 1522 01040 iu 100V 2222 344 21105 1522 0105 8 8 Parts List Table 8 2 Model 8551 Parts List continued Reference Designation Description and Tabor Commercial Part Number Part Number Vendor Code C5 C8 ELEC 100u 25V 2222 036 ELEC 1005 16V 2222 013 CER 22 SR155C220MAA CER 33P SR155C330MAA CER 430P SR155C431MAA CER in SR155C102MAA 1533 01070 59821 1532 0107P 59821 1500 02200 96095 1500 03300 96095 1500 04310 96095 1500 01020 96095 1500 01040 96095 C17 C18 C30 C39 C44 A C11 C15 C31 C14 C19 C20 C24 26 C40 41 C12 C13 C16 C21 C37 38 C42 43 C27 C33 CR1 CR2 CR7 CR4 CR6
87. MMAND TYPE COMMAND REN EOI IFC ATN SRQ LLO DCL SPE SPD SDC GTL GET UNL UNT Uniline Multiline Universal Unaddress Device Dependent STATE OF COMMENTS LINE X Set up for remote operation X Sent by setting EOI low X Clears Interface Low Defines data bus contents X Controlled by external device Low Locks out front panel controls Low Returns device to default conditions Low Enable serial polling Low Disables serial polling Addressed Low Returns unit to default condition Low Returns to local control Low Triggers device for reading Low Removes all listeners from bus Low Removes all talkers from bus High Programs Model 8550 for various modes X Don t Care See paragraph 4 9 for complete description 4 6 GPIB Operation erally this should be done before attempting to program the instrument over the bus The Model 8550 will indicate that it is in the remote mode by illuminating its front panel REM indicator To place the Model 8550 in the remote mode the controller must perform the following steps 1 Set the REN line true 2 Address the Model 8550 to listen NOTE Setting REN true without addressing will not cause the REM indicator to turn on however once REN is true the REM light will turn on the next time an address command is re ceived EOI End Or Identify The EOI command is used to positively identify the last byte in a multi byte transfer s
88. Message Terminator in model 8550 may be programmed by sending one of the following commands 20 New Line LF END terminator Z1 New Line LF terminator END EOI terminator Z3 No terminator NOTES 1 Most controllers use the LF character to terminate their input sequence Using the NO TERMINATOR mode Z3 may cause the controller to hang up unless special programming is used 2 Some controllers may require that EOI be present at the end of the string N N 4 13 DEVICE STATUS REPORTING Device status reporting defined by IEEE 488 2 builds upon and extends the original specifications of the status byte of the IEEE 488 1 document A complete model is defined for all status reporting Figure 4 3 illustrates the IEEE 488 2 status reporting model showing the IEEE 488 1 status byte which can be read by either a serial poll or Status Byte Query Summary of related common commands and queries is given in the following STB Returns NR1 which is the value of the IEEE 488 1 status byte and the MSS Muster Summary Status summary message OPC Sets the Operation Complete event bit in the Standard Event Status Register when all selected pending device operation have been com pleted OPC Places a 1 in the output queue when all selected pending operations are completed which in turn cause the MAV Message Available summary message to be generated CLS Clears all Event Registers summarized i
89. NS Nonoseconds Set repetition rate for internal burst US Microseconds MS Milliseconds STA MZ Millihertz Set sweep start frequency Model 8550 HZ Hertz KHZ Kilohertz MHZ Megahertz STP MZ Millihertz Set sweep stop frequency Model 8550 HZ Hertz KHZ Kilohertz MHZ Megahertz MRK MZ Millihertz Set sweep marker frequency Model 8550 HZ Hertz KHZ Kilohertz MHZ Megahertz SWT S Seconds Set sweep time Model 8550 MS Milliseconds Limit LO Off L1 On Complement CO Off normal output Model 8551 only C1 On Disable DO Off output enable D1 On Autovernier Mode A0 Off A1 On Autovernier Start MU Most significant digit up SU Second significant digit up LU Least significant digit up MD Most significant digit down SD Second significant digit down LD Least significant digit down Execute Self Test EST Current Parameter Setting CST M1 CTO TO W1 H0 A0 L0 CO DO BUR 0002 RPT 1 00 S Model 8550 AMP and OFS STA 1 000KHZ STP 9 000KHZ SWT1 00 S MRK5 000 KHZ active 1 000KHZ PLL ODEG TPH ODEG AMP 1 00V OFS Model 8551 AMP and OFS CST M1 CTO TO W1 H0 A0 L0 CO DO BUR 0002 RPT 1 00 S active LEE 10 0US TRE 10 0US TPH ODEG PLL ODEG 1 000KHZ DTY 50 WID 100US AMP 1 00V OFS OMV Current Parameter Setting CST M1 CTO TO W1 H0 A0 L0 CO DO BUR 0002 RPT 1 005 Model 8550 HIL and LOL STA 1 000KHZ STP 9 000KHZ SWT 1 00S MRK 5 000KHZ active 1 000 ODEG TPH ODEG HIL 0 50V LO
90. O signal is received This pulse triggers U18b and diverts the discharging current from Q36 to the timing capacitor The discharging current causes the voltage on the timing capacitor to drop linearly until the voltage level at the inverting input to the comparator equals the dc level at its non inverting input At this time the output of the comparator changes its state to 1 ECL level 0 8 V and sets U18b forcing a charge current on the timing capacitor from the output of U18b The comparator output then returns to its previous stable state of 0 ECL level and waits for the next triggering signal 6 8 2 Pulse Width Current Generator Circuit The current generator is controlled by a digital to analog converter U24 which receives its controlling signals from the CPU board and by an operational amplifier U23 The reference input to the digital to analog converter is supplied form the calibration board The voltage which is generated by the D A converter is converted to current by an operational amplifiers U22a and U22b transistors Q36 and Q38 and their associated components The amplitude of the ramp which is generated by the monostable circuit at the non inverting input of the comparator 020 is controlled by an operational amplifier U27b and resistors R99 and R103 Transistors Q35 Q37 and Q39 operational amplifier U27a and their as sociated components compensate for temperature variations and control the discharging current wh
91. ODE push button until the light behind BURST illuminates 6 Connect a BNC cable from the external stimulant to the front panel TRIG REF INPUT connector Make sure to observe external signal limits to avoid damage to the input circuit 7 When done with the counted burst operation remove the BNC cable from the input connector and select the normal continuous mode 3 17 2 Triggering The Function Generator With An Internal Stimulant When an external source is not available the operator has the option of using the built in trigger stimulant The internal trigger generator is a free running generator asynchronous to the main output generator with a programmable period Signal applied to the TRIG REF INPUT will have no effect on the generator when it is placed in internal trigger mode The internal trigger may be used in conjunction with the triggered and the counted burst modes it can not however be used in gated mode Operating the internal trigger generator in triggered and counted burst modes is described in the following 3 17 2 1 Triggered Mode When set to operate in internal triggered mode the output connector generates one waveform at pro grammable intervals Note that the programmed in ternal period should not exceed one half of the output waveform duration otherwise an error will result Model 8551 will indicate such errors with an ERROR LED To trigger the generator from the internal trigger generator proceed as fol
92. OMP 1M 5 1 4W 0100 01050 74902 R71 R85 10 1 1 4W 0104 10R00 74902 R72 R80 33 2 1 1 4W 0104 33R20 74902 R28 R29 49 9 1 1 4W 0104 49R90 74902 R25 61 9 1 1 4W 0104 61R90 74902 R34 R36 R67 R70 100 1 1 4W 0104 10000 74902 200 1 1 4W 0104 20000 74902 402 1 1 4W 0104 40200 74902 R35 R37 R39 R41 R42 R44 499 1 1 4W 0104 49900 74902 619 1 1 4W 0104 61900 74902 1K 1 1 4W 0104 10010 74902 R43 R45 R87 R88 1 1K 1 1 4W 0104 11010 74902 R89 1 24K 1 1 4W 0104 12410 74902 R46 R47 1 5K 1 4W 1 0104 15010 74902 R64 R65 R75 R84 R96 4 99K 1 1 4W 0104 49910 74902 R5 R7 R10 R11 R90 R91 R98 R104 10K 1 1 4W 0104 10020 74902 20K 1 1 4W 0104 20020 74902 23 2K 1 1 4W 0104 23220 74902 33 2K 196 1 4W 0104 33220 74902 100K 196 1 4W 0104 10030 74902 249K 1 1 4W 0104 24930 74902 301K 1 1 4W 0104 30130 74902 332K 1 1 4W 0104 33230 74902 R99 R102 2M 1 1 4W 0104 20040 74902 R66 VAR 20K 3386W 1 203 0203 0203A 80294 VAR 250K 3386W 1 254 0203 0254A 80294 NET MSP 08A 03 182G 1 8K 8 0110 01820 91637 NET MSP 05 01 272G 2 7K 5 0110 0272B 91637 NET 14 03 222 2 2K 14 0108 02220 91637 N 1 1 1 2 1 1 2 2 ll DUAL OP AMP LM1458N 0500 56500 04713 OP AMP OP200GP 0500 56350 24355 8 BIT SHIFT REGISTER CD4094B 0540 01100 27014 HA3 5033 5 0500 56340 36472 OP OP400GP 0500 56370 24355 U8 U11 U24 D A 10 BIT CONVERTER AD7533JN 0560 00700 1ES66 U10 U16 ECL NOR MC10102P 0500 40900
93. Offset 0 Phase Lock Offset 0 Start Trigger Phase Offset 0 Internal Trigger Period 1 00s Counted Burst 2 cycles Trigger Level 1 6V Start Trigger Phase Offset 0 Period 1 000ms Pulse Ramp Width 10 0s Duty Cycle 5096 Main Operating Mode Selection Normal Function Generator GPIB Status Local state Displayed Parameter Frequency VCO stimulant Internal Continuous Mode Carrier Modulation Control Off Output Waveform Sinewave Output Stand By On no output function generator Model 8550 accepts VCO am plitude and frequency modulating signals while Model 8551 accepts additional pulse width modulating signal 3 SYNC OUT The SYNC OUT connector outputs fixed amplitude pulses from a 500 source The leading edge of the SYNC output is synchronous with the leading edge at the main output connector 4 OUT The OUT connector is used as the main output for the function generator Output is driven from a 500 source Special care should be taken when these outputs are connected to the device under test because these outputs are capable of delivering up to 32Vp p For safety reasons after power on or after software reset the OUT connector is disconnected from the output circuit To resume normal operation press one of the two buttons above the OUT connector 3 2 3 Display And Indicators 1 DISPLAY The function of the numeric display is to indicate the value of the various parameters The display consists of a 4 digit
94. Operation There are no enable registers for the Calibration Failure Registers which are available for the pro grammer Thus whenever a calibration error occurs the information is immediately fed to the Status Byte Register 4 14 4 Pulse Ramp Error Status Register ERR The Pulse Ramp Error Status Register ERR is a special application of the status reporting It is avail able only on model 8551 Figure 4 5 illustrates the pulse ramp errors status register The 8 bits of the ERR contain information about programming errors of inter related pulse or ramp Program Data pa rameters such as pulse width and period Description of the various pulse ramp errors is given in the following The ERR summary message is fed to the Status Byte Register and can be monitored and reported back to the application programmer upon request The ERR is non destructively read with the ERR query The response to this query is a number that represents the sum of the binary weighted value of the Pulse Ramp Error Status Register The ERR register is cleared only by removing the related error that cause one or more bits in this register to be set TRUE Power off does not clear the ERR register There is no enable register for the Pulse Ramp Error Status Register which is available for the programmer Thus whenever such an error occurs the information is immediately fed to the Status Byte Register Description of the various bits in the Pulse Ra
95. POWER switch once to turn the power on 2 Depress the operating mode push buttons until the light behind PLL illuminates 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Connect a BNC cable from the reference source to the front panel REF INPUT connector Use a T connector and connect the reference signal to channel A on an oscilloscope 5 Connect a BNC cable from 8550 output to channel B on the oscilloscope 6 Set oscilloscope and observe that the two signals have the same frequency and are locked on the same phase 3 13 3 1 Generating Phase Offsets As discussed in paragraph 3 12 3 the generator is capable of generating phase offsets between the external reference signal and the main output con nector To generate phase offset proceed as follows 1 Repeat the operating instruction as in the previous paragraph 2 Depress the PHASE OFFSET push button until the light behind PLL illuminates 3 Use the MODIFIER push buttons to modify the present setting of the phase offset Observe that the oscilloscope and note that a phase offset is generated 4 Depress the P SET to restore phase offset to factory default phase offset value 0 3 13 3 2 Using Model 8550 as a Frequency Counter Model 8550 employs a built in frequency counter circuit which is used in different parts of the instrument for various purposes This internal counter is utilized when the instrument is placed
96. R13 4 02K 196 0104 40210 74902 R73 R81 4 99K 1 0104 49910 74902 R55 5 62K 1 0104 56210 74902 R43 MF8 25K 1 1 4W 0104 82510 74902 R54 MF 9 09K 1 1 4W 0104 90910 74902 W Parts List 8 3 Table 8 2 Model 8551 Parts List continued po gt 1 3 2 1 1 2 1 8 po oo 9 Reference Designation R6 R12 R15 16 R22 R24 28 R35 R37 40 R44 46 R2 R18 R19 R21 R23 R34 R20 RN1 RN2 RN3 RN4 RN5 U11 U12 U15 U20 21 U27 28 U36 U14 U16 U19 U24 U13 U17 U22 U23 U29 Description and Commercial Part Number 10K 196 1 4W 12 5K 196 1 4W 20K 196 1 4W 40 2K 196 1 4W 47 5K 196 1 4W 49 9K 196 1 4W 100K 196 1 4W 332K 1 1 4W NET CSC 09A 01 103G 10K 9 NET 03 08 103G 10K 8 NET CSC08A 03 182G 1 8 8 NET 09 01 272 2 7K 9 1K 5 TYPE 2322 642 63102 AD7228AJN DUAL OP AMP LM1458N QUAD OP AMPL LM324N OP AMPL TL084CP MAX 543ACP ANALOG SWITCH DG211CJ OP AMP 7 8 BIT SHIFT REGISTER CD4094B D A 10 BIT CONVERTER AD7533JN OP AMP LM741N ANALOG SWITCH DG411CJ MAX9690ACPA COMPARATOR LM393N BIMOS OP AMP CA3140E ECL FLIP FLOP MC10H131P 5 ECL NOR MC10H102P ECL NOR MC10102P ECL XOR XNOR MC10107P ECL DIVIDER MC10138P Front Panel Board Assembly 1 2 4 C1 C2 C3 DS1 DS4 8 4 Parts List CAP ELEC 100 16V 2222 036 CER 0 1u SR155C104ZAA 7 SIGMENT LED HDSP 5601 Tab
97. Register bits The binary equivalent of the number represents the values of the individual bits set into the Standard Event Status Enable register OPC Operation complete Command causes the device to generate the operation complete mes sage in the Standard Event Status Register when all pending selected device operations have been finished RCL Recall Command restores the state of the device to a state previously stored in the device s memory the device has more than one memory register the command must be followed by a number to specify which register is to be used The functions Mode Program Header Suffix and Data Data COMMON COMMANDS CLS ESEn OPC RCLn RST SAVn SREn TRG WAI COMMON QUERIES CAL ESE ESR IDN SRE 5 5 Description Clear status command Standard event status enable command Operation complete command Recall front panel set up command Reset command Save front panel set up command Service request enable command Trigger command Wait to continue command Calibration query Standard event status enable query Standard event status register query Identification query Operation complete query Service request enable query Read status byte query Self test query GPIB Operation 4 19 restored by the RCL command are the same as those affected by the RST command Model 8550 may recall settings in registers designated with nu
98. TION MODE Model 8550 provides three modulation modes FM AM and VCO Model 8551 offers PWM AM and VCO Placing the instrument in one of these modu lation modes is done by depressing the push buttons in the MOD section until the light nest to the required modulation mode The controlling signal is applied to the front panel INPUT BNC connector 3 14 1 Frequency Modulation FM Mode Model 8550 only The generator when placed in this mode operates as a free running voltage controlled oscillator The applied sinewave at the MOD INPUT connector determines modulation characteristics Model 8550 is placed in its FM mode when the light behind FM illuminates To frequency modulate the instrument first select the FM control mode and then apply the modulating signal to the front panel INPUT connector Observe external signal limits to avoid damage to the input circuit 3 14 2 Amplitude Modulation AM Mode The instrument when placed in this mode releases its amplitude control to an external control A signal with an appropriate characteristics modulates the amplitude at the main output connector Any of the available output waveforms may be modulated by the AM input modulating signal Model 8550 is placed in its AM mode when the light behind AM illuminates To amplitude modulate the generator first select the AM control mode and then apply the modulating signal to the front panel INPUT connector Frequency and amplitude limit
99. TL signal U11 pin 1 10 MHz counter reference 10MHz TTL level signal U11 pin 2 Counter synchronized gate Period 300ms width 50ms TTL signal U4 pin 2 Strobe line 500ns TTL positive going signal U4 pin 12 Strobe line 500ns TTL positive going signal U4 pin 15 Strobe line 500ns TTL positive going signal U4 pin 4 Serial clock 500ns bursts TTL pos going signal U5 pin 10 Serial data TTL level bursts positive going signal U2 pin 4 Keyboard interupt 30ms TTL positive going signal t Continuously depress one of the x1 or x1 U vernier push buttons Table 7 3 Digital Circuitry and Display Checks Adjustments and Troubleshooting 7 9 This page intentionally left blank 7 10 Adjustments and Troubleshooting Parts List 8 1 GENERAL This section contains information for ordering replace ment parts the replacement parts are available from Tabor Electronics 8 2 ORDERING INFORMATION When ordering replacement parts always include the following information a Instrument Model number b Instrument Serial number c Tabor part number d Part description Circuit designation where applicable e Table 8 1 Model 8550 8551 List of Vendors Section 8 f Vendor code number 8 3 VENDORS A list of vendors their address and their CAGE codes are given in Table 6 1 8 4 PARTS DESCRIPTION Table 8 2 lists parts that are used in Model 8551 Unless otherwise noted resis
100. TS The following troubleshooting procedures should be performed whenever the self diagnostic routine is insufficient to identify the source of the fault In some instances for example it will be impossible to execute a self calibration routine because the generator either does not power up at all the display is fully or partially blank or front panel controls can not be modified because software hardware related problem has locked the unit In such cases it is recommended to first verify proper operation of the power supply circuit the C P U circuit front panel display and keyboard operation WARNING The following procedures described in this section are for use only by qualified service personnel Do not perform these procedures unless qualified to do so The steps covered in the troubleshooting procedure may expose the individual to potentially lethal voltages that could result in personal injury or death if normal safety precautions are not observed For in circuit troubleshooting procedure it is re quired to remove the top and bottom covers With the above warning in mind carfully remove the covers and proceed with the following checks 7 6 1 Power Supply Checks It is highly suggested that the first step in trou bleshooting the Model 8550 8551 as well as any similar equipment would be to check the power supply If the various supply voltages within the instrument are not within the required limits trou
101. UT Figure 7 5 Connection Reference Oscillator Adjustment 7 4 Adjustments and Troubleshooting OSCILLOSCOPE 2 Change oscilloscope input setting to DC coupling and 500 input impedance Change oscilloscope ver tical gain setting to be 100 mV div Adjust trace vertical position so that it appears exactly at the center line 3 Connect 8551 output to the oscilloscope Adjust R66 on the pulse generator board until the base line is calibrated on the center line 7 3 6 Reference Oscillator Adjustment Equipment Synthesizer 1 Change 8550 8551 trigger level setting to 0 0 V 2 Set synthesizer frequency to one of the following frequencies 1 MHz 5 MHz or 10 MHz Connect synthesizer output to 8550 8551 TRIG IN BNC connector 4 Perform a self calibration procedure as described in paragraph 3 10 Note that a leading appears in front of the rotating bar indicating that Model 8550 8551 accepted the external frequency reference as its new standard 7 4 TROUBLESHOOTING The troubleshooting instructions contained in this section are intended for qualified personnel having a basic understanding of analog and digital circuitry The individual should also be experienced at using typical test equipment as well as ordinary trou bleshooting procedures The information presented here has been written to assist in isolating a defective circuit or circuit section isolation of the specified
102. User Manual 8550 8551 50 MHz Modulated Function Pulse Generators ES Tabor Electronics Ltd 9 Hatasia Street Tel Hanan Israel 20302 TEL 972 4 821 3393 FAX 972 4 821 3388 www taborelec com PUBLICATION DATE February 19 2006 REVISION F Copyright 2001 by Tabor Electronics rights reserved This book or parts thereof may not be reproduced in any form without written permission of the publisher WARRANTY Tabor warrants that all products manufactured by Tabor conform to published Tabor specifications and are free from defects in material and workmanship for a period of one 1 year from the date of delivery when used under normal conditions and within the service conditions for which they were furnished The obligation of Tabor arising from a Warranty claim shall be limited to repairing or at its option replacing without charge any product which in Tabor s sole opinion proves to be defective within the scope of the Warranty In the event Tabor is not able to modify repair or replace non conforming defective parts or components to the condition as warranted within a reasonable time after receipt thereof Buyers shall be credited for their value at the original purchase price Tabor must be notified in writing of the defect or nonconformity within the Warranty period and the affected product returned to Tabor s factory or to an authorized service center within thirty 30 days after discovery of such defect or nonc
103. V C O board The following is a list of possible counted burst calibration failures Possible solutions to remove the source of these errors are suggested FAIL 1 Check the counted burst circuit U19 U20 U21 U22 and their associated components on the V C O board 7 5 7 Pulse Width Calibration Failures Model 8551 Failures in the pulse width circuit is indicated by a blinking WID indicator with an associated displayed readout In general pulse width failures may generate as a result of faults in the pulse generator board The following is a list of possible pulse width cali bration failures Possible solutions to remove the source of these errors are suggested If FAIL 1 through FAIL 8 were detected refer first to the theory of operation section and verify proper operation of the following circuits on the pulse generator board monostable multivibrator pulse width current gener ator and auxiliary circuit Also verify proper operation of the pulse width reference control on the calibration board and the counter circuit on the C P U board For other failures proceed with the following list All of the following tests are performed on the pulse width board FAIL 1 Check C22 R78 K3 U25 R87 R88 and their associated components FAIL 2 Check U25 K3 and their associated components FAIL 3 Check K3 check C33 Q32 and their driving circuit 4 Check C34 Q29 and their driving circuit 5 Check C35 Q33 and their dr
104. a calibration error in the PLL and trigger circuits A value of 0 in the response indicates that the calibration was carried out successfully Note that complete information on calibration errors are available in the Calibration Failure Status Registers These auxiliary status registers are discussed in details later in this Table 4 7 Response Message Format Summary Command Response Format FRQ FRQ 1 000E 3 terminator AMP 1 00E 0 terminator OFS OFS 0 00E 0 terminator PLL PLL 00E 0 terminator PER PER 1 000E 3 terminator WID WID 10 00E 3 terminator DTY 50E 0 terminator LEE LEE 10 0E 6 terminator TRE TRE 10 0E 6 terminator RPT RPT 1 00E 0 terminator BUR BUR 2E 0 terminator TLV TLV 1 6E 0 terminator TPH TPH 00 0 DCO DCO 0 00E 0 terminator STP STP 9 000E 3 terminator SWT SWT 1 00E 0 terminator MRK 5 000E 0 terminator SSN SSN 9 000E 3 terminator MKN 5 000E 0 terminator ERR ERR 00000000 terminator FSA FSA 00000000 terminator FSB FSB 00000000 terminator FSC FSC 00000000 terminator NL END is normal terminator Ter minator may change see paragraph 4 12 4 section The calibration query does not require any local operator interaction to function Upon completion of CAL the device returns to the state just prior to the calibration cycle The various bits in the calibration error register are listed in the following Bit 0
105. a time The listening device will then read this infor 4 2 GPIB Operation mation and the appropriate software is then be used to channel the information to the desired location 4 3 IEEE 488 BUS LINES The signal lines on the IEEE 488 bus are grouped into three general categories The data lines handle bus information while the handshake and bus man agement lines assure that proper data transfer and bus operation takes place Each of the bus lines is active low so that approximately zero volts is a logic one The following paragraphs describe the purpose of these lines which are shown in Figure 4 1 4 3 1 Bus Management Lines The bus management group is made up of five signal lines that provide orderly transfer of data These lines are used to send the uniline commands described in paragraph 4 8 1 1 ATN Attention the ATN line is one of the more important management lines The state of the ATN line determines whether controller information on the data bus is to be considered data or a multiline command as described in paragraph 4 8 2 2 IFC Interface Clear Setting the IFC line true low causes the bus to go to a known state Figure 4 2 IEEE Handshake Sequence DATA X X SOURCE DAV VALID NRFD NDAC ACCEPTOR DATA TRANSFER BEGINS SOURCE ACCEPTOR DATA TRANSFER ENDS 3 REN Remote Enable Setting the REM line low sends the REM command This sets up ins
106. ace White Space Refer to paragraph 4 9 2 1 for the definition of White Space elements 4 9 3 Program Message Terminator A Program Message Terminator terminates a se quence of one or more definite length Program Message Unit gt elements There are three possible Program Message Terminator elements 1 NL new line 2 NL END and 3 END EOI NL is defined as a single ASCll encoded byte OA 10 decimal Leading White Space elements are permitted The instrument interprets any and all of the three terminators as semantically equivalent No alternative encoding are allowed Note that IEEE P981 amendment forbids the use of CR as a Pro gram Message Terminator element This is because some controller treat CR as the end of transmission and leave the LF character in the unit thereby creating an error in the controller 4 9 4 Command Program Header The Command Program Header represents the operation to be performed in a device The header may be optionally followed by associated parameters encoded as Program Data elements There are three defined Command Program Header elements Simple Command Program Header Compound Command Program Header and Common Com mand Program Header Simple Command Program Header is defined as Program Mnemonic For example FRQ Leading White Space ele ments are permitted Upper lower case alpha char acters are treated with th
107. age CONTROL POSITION Operating Mode Pulse Output Waveform Square Period 1600 us Pulse Width 800 us Transitions Linear 10 ns 8551 SETTING Square 16 0 V Ramp 16 0 V DMM READING 7 750 V 8 250 V 2 45 V 2 70 V 5 9 4 DC Characteristics Accuracy specifications 1 of setting 196 of amplitude 2 mV within 8 V 1 of setting 196 of amplitude 0 2 mV within 800 mV Equipment DMM 500 feedthrough termination 1 Set 8550 as follows CONTROL Amplitude POSITION 100 mV 2 Set DMM to DCV measurements 3 Connect 8550 output to DMM input Terminate the output with a 500 feedthrough termination Set 8550 offset and verify DMM reading as follows OFFSET SETTING DMM READING 7 50 V 7 422 to 7 578 V 5 00 V 4 947 V to 5 053 V 3 00 V 2 967 V to 3 033 V 1 00 V 0 987 V to 1 013 V 4 Change 8550 amplitude setting to 10 0 mV Set offset and verify DMM reading as follows OFFSET SETTING DMM READING 100 98 7mV to 101 3 5 9 5 Squarewave Characteristics Specified transition time 6 ns 1096 to 9096 of amplitude Specified aberration 596 of amplitude Equipment Oscilloscope 20dB attenuator 1 Set 8550 as follows CONTROL POSITION Frequency 1 000 MHz Amplitude 10 0 V Output Squarewave 2 Connect 8550 output to the oscilloscope input Use the 20 dB attenuator and set oscilloscope input impedance to 509 3 Set oscilloscope and verify that the rise and fall time
108. ages in the Standard Event Status Register Thus the application programmer can select reasons for the model 8550 to issue a ESB summary message bit by altering the contents of the ESE Register The Standard Event Status Enable Register is read with the ESE common query The response to this query is an number that represents the sum of the binary weighted value of the Standard Event Status Enable Register The Standard Event Status Enable Register is written using the ESE common command followed by a Decimal Numeric Program Data element representing the bit values of the Register A bit value one indicates an enabled condition Conse quently a bit value of zero indicates a disabled condition The Standard Event Status Enable Register is cleared by sending ESEO Summary of ESE messages is given in the following ESEO mask ESE1 ESB on Operation Complete ESE2 ESB on Request Control 4 ESB on Query Error ESE6 ESB on Device Dependent Error ESE16 ESB on Execution Error ESE32 ESB on Command Error ESE64 ESB on User Request ESE128 ESB Power on 4 14 3 Calibration Failure Status Registers A FSA B FSB and C FSC The Calibration Failure Status Registers FSA FSB an FSC are a special application of the status reporting Figure 4 4 illustrates the calibration failure status registers The 16 bits of the FSA contain information about calibration failures in the frequency and t
109. alibration board and is applied through Q28 CR13 U29a Q33 and Q23 through Q25 When the timing capacitor is clamped the current source which is made of Q27 R114 and R121 injects positive current into CR13 equal in magnitude to the current injected into CR10 6 4 2 Current Generator The current generator generates the necessary cur rents for the VCO and the trigger circuits The current magnitude determines the oscillation frequency within a selected range The frequency reference circuit which is located on the calibration board produces a voltage level which is applied to the VCO through J2 pin 13 This voltage is proportional to the frequency This voltage is then converted to alternating positive Theory of Operation 6 3 and negative currents by U15a Q22 U18 18 U17 and 021 The calibration board also produces a voltage level which determines the amplitude of the triangular waveform in the VCO circuit This voltage is applied to the VCO board through J2 pin 15 On lower frequencies the amplitude of the triangular waveform is 1 2 V On higher frequencies this level is reduced proportionally to compensate for delays in the VCO components 6 4 3 Range Capacitors and Multiplier The frequency at the main output is being generated by charging range capacitors with alternating currents from the current generator The range capacitors C36 and C21 through C24 are used for the 100 Hz to 50 MHz ranges They are connect
110. ameter VDCO Display dc output level parameter model 8550 only VSTP Display logarithmic sweep stop parameter model 8550 only VSWT Display sweep time parameter model 8550 only VMRK Display logarithmic sweep marker parame ter model 8550 only VSSN Display linear sweep stop parameter model 8550 only VMKN Display linear sweep marker parameter model 8550 only 4 10 10 Common Commands As discussed in previous paragraphs most instruments and devices in an ATE system use similar commands which perform identical functions to avoids the prob lem in which devices from various manufacturers used a different set of commands to enable functions and report status Some common commands and queries however are optional most of them are Table 4 6 Common Commands and Queries Summary mandatory Common commands and queries are listed in Table 4 6 The following set of common commands are utilized in the model 8550 optional common commands that are not included in the model 8550 command set will not be discussed here CLS Clear Status Command clears status data structures and forces the device to the Operation Complete Command Query Idle State If the Clear Status command immediately follows a lt Program Message Terminator gt the Output Queue and the MAV bit will be cleared ESE Standard Event Status Enable Command followed by a number in the range of O to 255 sets the Standard Event Status Enable
111. and their associated components The timing capacitors are charged by a positive constant current source which is made of Q18 and U18 creating a positive going linear voltage ramp which is applied to the positive input of U13 When this ramp meets the 1 2 V reference voltage level which is applied to the negative input of the comparator the current switch which is made of Q19 and Q20 reverses the polarity of the current which is applied to the timing capacitor discharging the timing capacitor and creating a negative going linear voltage ramp At this time the reference voltage at the negative input of the comparator is switched to 1 2 V by the current switch which is made of Q13 and Q14 When the negative going ramp meets the 1 2 V reference voltage level the current switch reverses the polarity again This sequence is automatically repeated creating a triangular waveform The above triangular waveform is buffered by an impedance converter Q12 ant its associated com ponents and applied to the rest of the circuits through K1 This buffer isolates the timing capacitors from the level comparator and provides sufficient current drive for the level detector The triangular waveform may be clamped at any voltage level between 1 2 V and 1 2 V for the purpose of generating start phase offsets This is done by applying a program mable level at the cathode of CR10 diode This programmable level is generated by circuits located on the c
112. any of the steps covered in this section may expose the indi vidual to potentially lethal voltages that could result in personal injury or death if normal safety precautions are not observed 7 2 ADJUSTMENTS 7 2 1 Environmental Conditions Adjustments should be performed under laboratory conditions having an ambient temperature of 24 5 C and a relative humidity of less than 7096 If the instrument has been subjected to conditions outside these ranges allow at least one additional hour for the instrument to stabilize before beginning the ad justment procedure Between adjustments Always leave top cover on the unit to keep internal tem perature as stable as possible Recommended Model Counter HP5334B DMM HP3478AA Function generator Wavetek model 90 Synthesizer Marconi 2019 Oscilloscope Tektronix 2465B Distortion Analyzer K H 6900 20dB Attenuator Instrument Table 7 1 Recommended Test Equipment Tektronix 011 0086 00 Section 7 7 2 2 Warm Up Period Most equipment is subject to at least a small amount of drift when it is first turned on To ensure long term calibration accuracy turn on the power to the Model 8550 8551 and allow it to warm up for at least 30 minutes before beginning the adjustment procedure 7 2 3 Recommended Test Equipment Recommended test equipment for calibration is listed in Table 5 2 Test instruments other than those listed may be used only if their specifications equal or exc
113. apan 55101 Texas Instruments 13500N Central Expressway Dallas TX 75265 01295 TRW 14520 Aviation Blvd Lawndale 90260 0128551 Wavetek Datron 9045 Balboa Avenue San Diego CA 92123 23338 Table 8 2 Model 8550 8551 Parts List Reference Description and Tabor Qty Designation Commercial Part Number Part Number Vendor Code Current Generator Board Assembly 6100 6210 23338 C8 CAP CER 3 3P SR155C3R31MAA 1500 03R30 96095 C38 CAP CER 15P SR155C150MAA 1500 01500 96095 C20 CAP CER 470P SR155C471MAA 1500 04710 96095 C27 CAP CER 220P SR155C221MAA 1500 02210 96095 C16 C24 C39 CAP CER 10n SR155C103MAA 1500 01030 96095 C40 CAP CER 50n SR155C503MAA 1500 05000 96095 C10 C11 C15 C19 C21 C22 C23 C25 C28 C31 CER 0 1u SR155E104ZAA 1500 0104A 96095 C14 C18 CAP TANT 1 05 T350A105M025AS 1540 01050 31439 C1 C7 C13 C17 C26 C36 C37 CAP TANT 10u T350B106M025AS 1540 0106B 31433 12 CAP ELEC 100 16V 2222 013 1532 0107P 59821 C32 C35 CAP ELEC 100 25V 2222 036 1533 01070 59821 CR2 DIODE HOT CARRIER 5082 2810 0300 10200 54893 DIODE ZENER 1N751A 5 1 V 0300 20010 14936 DIODE 1N4151 0300 00400 14936 CON FEMALE 2X8 90152 2216 3000 30520 27264 CON RF MALE 131 1701 201 3000 16000 74970 8 2 Parts List Table 8 2 Model 8551 Parts List continued Reference Description and Tabor Designation Commercial Part Number Part Number Vendor Code L1 BEAD Ferrite CERAMAG24 57 1355 4200 00000 59821 TSTR 309 0400 02510 17856 TSTR 2N5210 0400 019
114. at bit 6 line is asserted pulled to a low voltage when the status byte is sent The response represents the sum of the binary weighted values of the Status Byte Register Reading the Status Byte Register with a serial poll sets the RQS message FALSE until a new reason for service has occurred The STB portion of the Status Byte Register is read non destructively The value of the status byte is not altered by a serial poll Once the model 8550 has generated an RQS its status byte should be read to clear the SRQ line so the controller can detect an SRQ from another device Otherwise the instrument will con tinuously assert the SRQ line 4 14 1 2 Reading with the STB The STB common query causes the generator to send the contents of the Status Byte Register and the MSS Master Summary Status summary message as a single NR1 Numeric Response Message element The response represents the sum of the binary weighted values of the Status Byte Register The STB common query does not alter the status byte 4 14 1 3 Clearing the Status Byte Register The entire Status Byte Register can be cleared by removing the reasons for service from the Auxiliary Status Registers Sending the CLS common com mand to the device after a Program Message Terminator and before Query Message Unit ele ments clears the Standard Event Status Register and clears the output queue of any unread messages With the output queue empty the MAV sum
115. at this level until end of sweep Stop Sweep Resolution Same as Frequency resolution LINEAR SWEEP CHARACTERISTICS Modes Same as in logarithmic sweep Width 3 decades maximum Time Continuously adjustable from 10mS to 9995 NOMINAL Sweep Out 0 to 5V 5 Sweep Steps Depends on sweep time and range Automatically adjusted by the instrument to get the maximum steps per sweep time Maximum steps are 1000 minimum steps are 2 Marker Output Same as in logarithmic sweep Stop Sweep Resolution Same as Frequency resolution CONTROL CHARACTERISTICS Modes VCO AM FM Model 8550 PWM Model 8551 Input Via front panel CONTROL INPUT BNC connector Impedance 10KQ 5 Max Input Voltage 10V VOLTAGE CONTROLLED OSCILLATOR VCO FM CHARACTERISTICS VCO Sensitivity OV to 4 7V 20 produces 1 1000 frequency change from main frequency when main frequency is set to 9999 counts FM Sensitivity OV to 0 5V 70mV modulates to 1 deviation from center frequency Modulation Bandwidth DC to 50KHz AM CHARACTERISTICS Modulation Input DC coupled Modulation Bandwidth DC to 1MHz Modulation Range 0 to 20096 reduced to 70 at 1MHz Sensitivity OV to 5Vp p produces 10096 modulations OV to 10Vp p produces suppressed carrier amplitude modulation SCAM General Information 1 5 Table 1 1 Model 8550 8551 Specifications continued Envelop Distortion Reference Input Impedance Sensitivity Max In
116. ating Mode Model 8551 3 13A 4 Phase Locking Generator Operating Mode Model 8551 3 13A 4 1 Generating Phase Offsets 3 13A 4 2 Using Model 8551 As Counter Timer 3 14 Selecting A MODulaton Mode 3 14 1 Frequency Modulation FM Mode Model 8550 Only 3 14 2 Amplitude Modulation AM Mode 3 14 3 Voltage Controlled Oscillator VCO Mode 3 14 4 Pulse Width Modulation PWM Mode Model 8551 Only 3 15 Selecting an Output Waveform 2 2 ie a e a a O a 3 16 Disabling Ehe Output coe E cb 3 17 Triggering The Function Generator 3 17 1 Triggering The Generator With An External Stimulant 3 17 1 1 Triggered Mode 3 17 1 2 Gated ModE 8 xs AE eene eae sette ies 3 17 1 3 Counted Burst Mode 3 17 2 Triggering The Generator With An Internal Stimulant 3 17 2 1 Triggered dpe ado ee dd ge Re Rd 3 17 2 2 Counted Burst Mode 3 17 3 Triggering The Generator With A Manual Stimulant 3 18 Using The Offset s og koc pom mom Ron BUR VR RR ee Gg 3 19 Using Front Panel Setups 3 19 1 Storing Set ups 3 19 2 Recalling Se
117. aying Status Data Structure is altered The description of the various bits within the Status Byte Register is given in the following Bit 0 Pulse Ramp Error Status Summary The state of this bit indicates whether or not a pulse ramp programming error in the Pulse Ramp Error Status Register ERR have occured The ERR summary message is true when a pulse ramp programming error have been detected Bit 1 Calibration Failure Status Summary C The state of this bit indicates whether or not a calibration failure in the Calibration Failure Status Byte C FSC have occurred The FSC summary message is true when a calibration error was have been detected Bit 2 Calibration Failure Status Summary B The state of this bit indicates whether or not a calibration failure in the Calibration Failure Status Byte B FSB have occurred The FSB summary message is true when a calibration error was have been detected Bit 3 Calibration Failure Status Summary A The state of this bit indicates whether or not a calibration failure in the Calibration Failure Status Byte A FSA have occurred The FSA summary message is true when a calibration error was have been detected Bit 4 Message Available Queue Summary Message MAV The state of this bit indicates whether or not the output queue is empty The MAV summary message is true when the output queue is not empty This message is used to synchronize information exchange with the controller The con
118. between the triggering signal and the generated output signal The trigger phase offset has no effect on external signals having a high slew rate such as square waves The trigger phase offset parameter may be programmed within the range of 90 Preset value is set to 0 4 TRIGGER PER A built in generator provides internal triggering stimulant in such cases where an external signal is not available The displayed value specifies the interval between consecutive triggering se quences The trigger period parameter may be pro grammed within the range of 20us to 999s Preset value is set to 1 00s BUR Model 8550 has the capability of generating a burst of waveforms at its output connector having an exact number of complete cycles The counted burst function operates on all output waveforms except on DC output The burst of counted number of output cycles can be programmed within the range of 1 to 4000 output cycles Preset value is set to 2 cycle LEVEL The LEVEL parameter sets the trigger voltage level at the TRIG INPUT connector The output signal will trigger the function generator at the point set by LEVEL parameter The trigger level parameter may be programmed within the range of 10 0V to 10 0V Preset value is set to 1 6V 3 2 1 3A Main Parameters Model 8551 There are four MAIN PARAMETERS push buttons which are used to modify the displayed reading Each time a button is depressed a different parameter i
119. between this manual and your instrument Technical corrections to this manual if any are listed in the back of this manual on an enclosed MANUAL CHANGES sheet 1 4 OPTIONS Model 8550 offers a rack mounting option designated as OPT 001 Opt 001 is field installable or may be ordered with new instruments from the factory 1 5 SAFETY CONSIDERATIONS Model 8550 has been manufactured according to international safety standards The instrument meets EN 61010 1 and UL 1244 standards for safety of commercial electronic measuring and test equipment for instruments with an exposed metal chassis that is directly connected to earth via the power supply cable Before the instrument is switched on make sure that protective earth terminal is connected to a protective earth via the power cord Do not remove instrument covers when operating or when power cord is connected to mains Any adjustment maintenance and repair of the opened instrument under voltage should be avoided as much as possible but when inevitable should be carried out only by a skilled person who is aware of the hazard involved 1 6 ACCESSORIES SUPPLIED Model 8550 is supplied with ac power cord and with an instruction manual Extra manual is available on request 1 7 SPECIFICATIONS Instrument specifications are listed in Tables 1 1 These specifications are the performance standards or limits against which the instrument is tested NOTE All specifications in
120. binary equivalent represents the value of the bits of the status byte 1572 Self Test Query Tells the device to perform an internal self test and report back to the controller if any errors are detected The generator responds to this query with a number A value of 1 in the response indicates that the self test routine has detected an error A value of 0 in the response indicates that the self test was carried out success fully 4 12 3 Response Header X The Response Header from the Response Mes sage string may be suppressed using this command When the Response Header is suppressed the output data string is 3 byte shorter The Response Header may be suppressed using the following commands Response header OFF X1 Response header ON 4 12 4 Response Message Terminator Z To allow a wide variety of controllers to be used the terminator can be changed by sending the ap propriate command over the bus The default value is New Line LF End EOI sequence mode 20 The terminator sequence will assume this default value after receiving a DCL or SDC The EOI END line on the bus is usually set low by the device during the last byte of its data transfer sequence In this way the last byte is properly identified allowing variable length data words to be transmitted The Model 8550 will normally send EOI during the last byte of its data string or status 4 24 GPIB Operation word The Response
121. bit is set when an error in a device function occurs For example the following Program Message will cause DDE error AMP10E 0 OFS10E 0 Both parameters are legal and within the specified limits however the function generator is unable to generate such an amplitude and offset combination Following the Device Dependent Error the generator continues to process the input stream Bit 4 Execution Error This bit is generated if the Program Data element following the header is outside of the legal input range of the generator Bit 5 Command Error This bit indicates the generator received a command that was a syntax eror or a command that the device does not implement A GET receive inside a Program Mes sage will also cause a Command Error Bit 6 User Request This event bit indicates that one of a set of local controls the MANUAL push button in this case has been activated This event bit occurs regardless of the remote or local state of the device Bit 7 Power On This bit indicates that the device s power source was turned off then on since the last time that the register was read 4 14 2 1 Standard Event Status Enable Register ESE The Standard Event Status Enable Register allows one or more events in the Standard Event Status GPIB Operation 4 27 Register to be reflected in the ESB summary message bit The Standard Event Status Enable Register is an 8 bit register that enables corresponding summary mess
122. bleshooting the remaining circuits can be very difficult Table 7 2 shows several checks that can be made to the power supplies within the generator In addition to the normal voltage checks it is also a good idea to check the various supplies with an oscilloscope to make sure that no noise or ringing is present In case of a dead short between one of the supplies to the common ground it would be best to disconnect the entire supply section from the remaining of the circuitry and then determine whether the problem is in the power supply or in the remaining circuits Model 8550 8551 is equipped with such quick disconnect points which are located on the bottom side of the main PC board To access these points it is necessary to remove the bottom cover and then to remove the solder layer from these points While troubleshooting the power supply section bear in mind that the 15 V supply also provides Test Point Description Test Result 24 V 24 V supply 23 V to 25 V 24 24 V supply 23 V to 25 V 15 V 15 V supply 14 4 V to 15 6 V 15 V 15 V supply 14 4 V to 15 6 V 5 V 5 V supply 48 V to 45 2 V 5 2 V 5 2 V supply 5 V to 54 V Table 7 2 Power Supply Checks 7 8 Adjustments and Troubleshooting the reference voltage to the 5 V Therefore it would be impossible to troubleshoot the 5 V supply if the 15 V supply is defective Similarly the 5 V supply is used as a reference vo
123. cuit are converted from ECL to TTL by a comparator 035 6 6 OUTPUT AMPLIFIER BOARD The following paragraphs contain descriptions of the various circuit that are available on the Output Am plifier board The circuits that are discussed here are the pulse shaper circuit the waveform selector circuit the amplitude modulator circuit the step at tenuator the power amplifier the offset and amplitude sensing circuit and the rise time sensing circuit Complete and detailed schematics of this board are located at the end of this manual 6 6 1 Pulse Shaper Circuit The purpose of the pulse shaper is to convert the signal from the level detector to pulses having very fast rise and fall times and with precise amplitude The pulse shaper is located on the output amplifier assembly board The squarewave for the pulse shaper may come either from the VCO board or from the pulse width board Model 8551 only The signal is routed to the output amplifier board through the connector J2 pin 2 The squarewave signal is conditioned by the line receiver U6 and routed to the pulse shaper input The pulse shaper consists of emitter coupled transistors Q2 Q3 Q4 and Q5 positive and negative current generators U5b Q6 R11 5 Q7 10 and level shifter made of diodes CR1 through When the generator is set to operate in squarewave function the output of the pulse shaper alternates between the positive current source and the negative cur
124. d on contact tort or any other legal theory Tabor Electronics Ltd REPAIR AND CALIBRATION REQUEST FORM To allow us to better understand your repair requests we suggest you use the following outline when calling and include a copy with your instrument to be sent to the Tabor Repair Facility Model Serial No Date Company Name Purchase Order Billing Address City State Province Zip Postal Code Country Shipping Address City State Province Zip Postal Code Country Technical Contact Phone Number Purchasing Contact Phone Number 1 Describe in detail the problem and symptoms you are having Please include all set up details such as input output levels frequencies waveform details etc 2 problem is occurring when unit is in remote please list the program strings used and the controller type 3 Please give any additional information you feel would be beneficial in facilitating a faster repair time i e modifications etc 4 15 calibration data required Yes No please circle one Call before shipping Ship instruments to nearest support office Note We do not accept listed on back collect shipments SAFETY PRECAUTIONS Protect yourself Follow these precautions Don t bypass the power cord s ground lead with two wire extension cords or plug adapters e Don t disconnect the green and yellow safety earth ground wire that connects the ground lug of the power receptacle to the chassis ground termina
125. dge value may only be selected when the pulse function generator is set to operate in its linear transition mode oth erwise the trailing edge transition time is set to its fastest position The trailing edge transition time parameter may be programmed within the range of 8ns to 99 9ms Preset value is set 10 0us 4 TRIGGER PER A built in generator provides an internal triggering stimulant in such cases where an external signal is not available The displayed value specifies the interval between consecutive triggering se quences The trigger period parameter may be pro grammed within the range of 20us to 999s Preset value is set to 1 00s BUR Model 8551 has the capability of generating a burst of waveforms at its output connector having an exact number of complete cycles The counted burst function operates on all output waveforms except on DC output The burst of counted number of output cycles can be programmed within the range of 1 to 4000 output cycles Preset value is set to 2 cycles LEVEL The LEVEL parameter sets the trigger voltage level at the TRIG INPUT connector The output signal will trigger the function generator at the point set by LEVEL parameter The trigger level parameter may be programmed within the range of 10 0V to 10 0V Preset value is set to 1 6V PHASE The PHASE parameter inserts a phase offset between the triggering signal and the generated output signal The trigger phase offset has no ef
126. dry area that is not subject to extreme temperature variations or conditions which may cause moisture to condense on the instrument 2 11 LONG TERM STORAGE OR RE PACKAG If the original container is not available proceed ING FOR SHIPMENT as follows 1 Before packing the unit place all accessories into a plastic bag and seal the bag 2 For extended storage or long distance shipping only use U S government packing method II C and tape a two unit bag of desiccant per MIL D 3464 on the rear cover 3 Place a 13 cm 5 inch by 30 cm 12 inch piece of sturdy cardboard over the front panel for protection 1 If the original wrappings packing material and 4 Place the counter into a plastic bag and seal container have been saved re pack the instrument the bag and accessories originally shipped to you If the 5 Wrap the bagged instrument and accessories original container is not available one may be pur in one inch thick flexible cellular plastic film cushioning chased through the Tabor Service Department at material per PREC 799 sand place Bag the factory per MIL B 131 Extract the air from bag and heat 2 Be sure the carton is well sealed with strong seal uoti tape or metal straps 6 Place bagged instrument and accessories into an oversized card board box per PPP B 636 type CF class WR variety SW grade Fill additional If the instrument is to be stored for a long period or shipped proceed as d
127. e device under test Safe operation requires that the instrument covers be closed at all times during operation Carefully read the Safety Precautions instructions that are supplied with your instrument Instruments cables leads or cords should not be connected to humans Before performing any maintenance disconnect the line cord and all test cables DECLARATION OF CONFORMITY We Tabor Electronics Ltd 9 Hatasia Street Tel Hanan ISRAEL 20302 declare that the 50 MHz Pulse Function Generators Model 8550 and Model 8551 meet the intent of Directive 89 336 EEC for Electromagnetic Compatibility and complies with the requirements of the Low Voltage Directive 73 23 EEC Compliance was demonstrated to the following specifications as listed in the official Journal of the European Communities Safety EN 61010 1 IEC 1010 1 1990 Amendment 1 1992 EMC EN 50081 1 Emissions EN 55022 Radiated Class B EN 55022 Conducted Class B EN 50082 1 Immunity IEC 801 2 1991 Electrostatic Discharge IEC 801 3 ENV50140 1993 RF Radiated IEC 801 4 1991 Fast Transients Model 8550 and Model 8551 were tested in typical configuration CONTENTS SECTION 1 GENERAL INFORMATION 1 EMEN LP MMC Bee 1 1 2 Description 2 est ux ber Alas a 1 1 3 Instrument and Manual Identification 1 2 4 PIONS 205 ete ener SONO
128. e operating mode command controls the mode that the model 8550 operates Operator may select between four different operating modes normal op erating mode linear sweep mode logarithmic sweep mode and phase locking generator mode Model 8551 has different operating modes normal operating mode variable duty cycle pulse generator mode fixed duty cycle pulse generator mode and phase locking generator mode The model 8550 operating mode may be pro grammed by sending one of the following commands Table 4 5 Device Dependent Command Summary Mode OPERATING MODE Model 8550 OPERATING MODE Model 8551 SWEEP DIRECTION MODEL 8550 TRIGGER MODES CONTROL MODES OUTPUT WAVEFORMS OUTPUT MODE Model 8551 Model 8551 EDGE CONTROL Model 8551 Program Header and Data CTO CT1 CT2 CTS CT4 Description Normal Linear Sweep Logarithmic Sweep PLL Normal Pulse Fixed Duty Cycle PLL Start to Stop up Stop to start down Start to stop to start up down Stop to start to stop down up Normal continuous mode External Trigger External Gate External Burst Internal Trigger Internal Burst Off FM Model 8550 AM PWM Model 8551 VCO DC Model 8550 Sinewave Triangle Squarewave Fixed base line positive squarewave Fixed base line negative squarewave Ramp Model 8551 Normal output Disabled output Pulse Ramp complement OFF Pulse Ramp complement ON Fastest edge tra
129. e range of the required specifications otherwise refer to the troubleshooting procedures given later in this section Perform the following adjustment procedure If an adjustment can not be made to obtain a specific result refer to the troubleshooting procedures NOTE If not otherwise specified before every adjustment set Model 8550 8551 controls to factory defaults by depressing 2nd and DCL in sequence Always connect the output BNC connector through a 500 feedthrough termination 7 3 ADJUSTMENT PROCEDURE 7 3 1 Distortion Adjustment Equipment Distortion analyzer MODEL 80 81 STATE MAN PARAMETERS TRIGGER 0 OUTPUT OUT Figure 7 1 Connection Distortion Adjustment 7 2 Adjustments and Troubleshooting 1 Connect 8550 8551 output to distortion analyzer input as shown in Fuigure 7 1 2 Adjust V C O board trimmers R22 and R101 repeatedly until the distortion reading on the analyzer is adjusted to minimum but not more than 0 896 3 Change 8550 8551 setting to 9 999 KHz Repeat step 2 for best distortion reading Note that each one of these resistors contribute a small amount to the distortion correction It is up to the service technician to find the most effective sequence to perform this step Repeat steps 2 and 3 until distortion reading is equal and minimal in both frequencies 7 3 2 Sine Level Adjustment Equipment DMM 1 Connect 85
130. e same semantic equiva lence Compound Command Program Header is not used in model 8550 and will not be discussed here A Common Command Program Header is defined as Program Mnemonic gt For example TRG Leading White Space ele ments are permitted Upper lower case alpha char acters are treated with the same semantic equiva lence 4 9 5 Query Program Header The Query Program Header represents the op eration to be performed in a device A Query Program Header causes the device to generate a response This element may be optionally followed by associated parameters encoded as Program Data elements There are three defined Query Program Header elements Simple Query Program Header Compound Query Program Header and Common Query Program Header A Simple Query Program Header is defined as Program Mnemonic gt For example FRQ Leading White Space ele ments are permitted Upper lower case alpha char acters are treated with the same semantic equiva lence Compound Query Program Header is not used in model 8550 and will not be discussed here A Common Query Program Header is defined as lt Program Mnemonic gt For example CAL Leading lt White Space gt ele ments are permitted Upper lower case alpha char acters are treated with the same semantic equiva lence 4 9 6 Program Data A lt Program Data gt functional element is used to convey a var
131. e waveform at the OUTPUT con nector The waveform at the output connector is automatically synchronized with the external transition To trigger the generator from an external source proceed as follows 1 Depress the POWER switch once to turn the power on 2 Select the required output waveform and set up the parameters to the required characteristics 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Depress the TRIGGER MODE push button until the light behind TRIG D illuminates 5 Connect a BNC cable from the external stimulant to the front panel TRIG REF INPUT connector Make sure to observe external signal limits to avoid damage to the input circuit 6 When done with the triggered operation remove the BNC cable from the input connector and select the normal continuous mode 3 17 1 2 Gated Mode When set to operate in gated mode the first positive going transition at the TRIG REF INPUT connector enables the generator output The consecutive nega tive going transition disables the generator output First output waveform is synchronized with the first external transition Last waveform is always com pleted The TRIG REF INPUT connector is sensitive to dc levels If this input is left open and the trigger level was set to a negative voltage the gen erator may self gate To gate the generator from an external source proceed as follows 1 Depress the POWER switch once
132. ected waveform at the main output connector Similarly to the amplitude the offset parameter is specified and accurately controlled only when the output is terminated with 500 Offset control has no effect on the SYNC output connector The offset parameter may be pro grammed within the range of 0 00mV to 7 95V Preset value is set to OmV P OFST The Model 8551 output may be locked to an external signal The operator may then introduce a phase offset between the leading edge of the external signal and the leading edge of the signal at the output connector The phase offset is pro grammed with the P OFST parameter The phase offset parameter may be programmed within the range of 180 Preset value is set to 0 2 PULSE PER Similar to the FREQ parameter the PER sets the period of the selected output waveform Period is defined for repetitive signals only When the pulse function generator is set to operate in triggered mode the programmed period value has no effect on the output In gated mode the period defines the repetition rate within the gating signal The programmed period retains its value at both SYNC and the main output connectors The period parameter may be programmed within the range of 20 00ns to 99 99s Preset value is set to 1 000ms WIDTH The pulse width parameter defines the time interval between two consecutive transitions positive to negative transition in normal output mode or negative to positive trans
133. ed to the VCO circuit through the relay K2 They are switched in and out of the circuit by the transistors Q8 through Q11 The capacitor multiplier is used for the 10 mHz to 99 99 Hz ranges The function of this circuit is to generate an equivalent large capacitance The larger values of capacitors are required to generate lower frequencies The capacitor multiplier is formed by U1 U2 U3 and their associated components The multiplier ratio is selected by changing the ranging resistors in the negative feedback path of U1 6 4 4 Sine Shaper The sine shaper consists of a series of differential stages which are formed by limiting amplifier arrays U9 011 and U12 The differential stages are con nected in parallel and receive the drive signal from the triangle buffer output U10 This circuit takes advantage of the non linear characteristics of the transistors and by biasing them to different dc levels the output of the common collector is shaped to a sinewave The sinewave is then routed through R51 to an amplifier amplified and re biased to oscillate around O V with a differential amplifier which is formed by Q2 through Q7 and their associated components Q1 is an electronic switch which removes the supplied current from the sine amplifier when it is not being used 6 4 5 Trigger and Burst Circuit The trigger circuit is active when one of the trigger modes is selected lt provides 4 different trigger 6 4 Theory of Operatio
134. ed with these com mands Included is a Wait to Continue command which forces the devices to complete all previous commands and queries The Operation Complete command tells the device to set bit 0 in the Standard Event Status register when it completes all pending operations 5 Device Trigger These commands enable a device to be triggered and specify how it responds to the trigger message The Define Device Trigger command stores a sequence of commands which the device will follow when the Group Execute Trigger GET is received 6 Stored Settings These commands are used to save the state of the device under control to be used at a later time The Save command stores the present state of the device in the device s memory If there is more than one location in which this data can be stored the command is followed by a number which designates the storage register to use The Recall command restores the state of the device as stored in its memory from the previous Save command As with the Save command the Recall command must be followed by a number to specify the register from which the stored settings are to be recalled 4 9 DEVICE LISTENING FORMATS This paragraph discusses the formatting of Program Message elements received by a device from its System interface Allowable IEEE 488 2 Program Message is composed of sequence of Program Message units each unit representing a program command Each program command is c
135. edge transitions ll GPIB Operation 4 17 4 10 8 Parameter Programming The parameter programming command sets the func tion generator to the various levels which are required for the unit under test There are 19 different parameters which may be modified using this com mand The command message unit is comprised of three parts the command program headers the decimal numeric program data the suffix program data optional and the program message termi nator The command program header mnemonic is in dependent of control location on the front panel but relates to front panel nomenclature For example FRQ mnemonic is related to front panel Frequency marking The decimal numeric program data is a flexible version of numeric representation denoted by NRf Operator may choose to program decimal numeric program data using NR1 NR2 or NR3 formats Examples of the various decimal numeric program data is given in the following NR1 elements consists of a set of implicit point representations of numeric values i e 12345 NR2 elements are the representations of explicit point numeric values i e 12 345 NR3 elements are representations of scaled explicit radix point numeric values together with an exponent notation i e 123 456E 3 The suffix program data element permits the use of suffix following the NRf The suffix expresses associated units and optional multipliers that
136. eed the required characteristics 7 2 4 Adjustment Procedures All adjustments are performed with the POWER switch ON The top cover should be removed to allow access to test points and adjustments Always perform a self calibration sequence before starting the adjustment procedure The self calibration if exe cuted without any failure ensures proper operation of the generator If self calibration failure was en countered refer first to the troubleshooting instructions in this section to verify and rectify the source of this failure Instructions how to self calibrate the function generator is given in paragraph 3 10 WARNING Take special care to prevent contact with live circuits or power line area Minimum Specifications 100MHz universal counter 0 1V 500Vac rms DC 0 05 Sine square 2mHz 20MHz 20Vp p 80KHz 1040MHz 1ppm 400MHz analog bandwidth 10Hz 1MHz 0 0196 resolution 500 2W 296 Adjustments and Troubleshooting 7 1 which could cause electrical shock resulting in serious injury or death Use an isolated tool when making adjustments When necessary refer to the component layouts in Section 9 for determining adjustment points Follow the procedure in the sequence indicated because some of the adjustments are interrelated and de pendent on the proceeding steps Verify that the generator is functioning according to the performance checks Make sure that all results are within or close to th
137. eir associated components negative going ramp is limited to 1 5 V by a circuit made of U1a Q1 and their associated components The 1 5 voltage limits are referenced to the 5 V reference voltage on the main board The generated squarewave with its linear transition times is buffered by a dual FET circuit Q8 and buffer U5 and then routed to the appropriate input on the output amplifier board 6 8 5 Transition Times Current Generator As discussed above the transition times current generator circuit generates the required current to charge the timing capacitors for the transition time ramps The current generator is controlled by a digital to analog converters U8 and U11 which receives their controlling signals from the CPU board The reference input to the digital to analog converters is supplied form operational amplifiers U2a and U2b and are referenced to the 5 V reference voltage on the main board The voltage which is generated by the D A converters is converted to positive and negative currents by quad operational amplifiers U6 and 07 transistors Q14 through Q21 and their associated components 6 8 6 Auxiliary Circuits The information for the various gates and digital controls on the pulse generator board is received from the CPU board in a form of serial data The serial data is then converted to parallel data by a train of serial to parallel converters U28 U26 U12 U13 U14 U9 and U4 and is latched for con
138. emented in Model 8550 Therefore it shall not be discussed in this manual 4 9 6 5 Arbitrary Block Program Data The Arbitrary Block Program Data functional ele ment is not implemented in Model 8550 Therefore it shall not be discussed in this manual 4 9 6 6 Expression Program Data The Expression Program Data functional element is not implemented in Model 8550 Therefore it shall not be discussed in this manual 4 10 DEVICE DEPENDENT COMMAND PROGRAMMING IEEE 488 2 device dependent commands are sent to the Model 8550 to control various operating conditions such as display modify operating mode output and parameter interrogate Each command is made up of a program command or query header followed by program data program suffix and terminated by program message terminator The IEEE bus treats device dependent commands as data in providing that ATN is high when the commands are transmitted For example the output amplitude is programmed by sending the following Program Message Unit AMP 10 5V A number of Program Message Unit elements may be grouped together in one Program Message provided that each Program Message Unit is sepa rated by a Program Message Unit Separator gt Program message Unit elements within a Program Message are executed exactly in the same order they are received from the controller The Model 8550 ignores all non printable ASCII characters 00 HEX through 20 HEX excep
139. endent commands set HP 8116A is a 50MHz function generator that provides similar functions to those offered in Models 8550 and 8551 The three instruments do not offer the same functions and feature however in places where they are the same the GPIB commands that are used for programming these instruments are the same This emulation mode saves extremely valuable programming time when replacing Model 8116A by Model 8550 or Model 8551 The complete set of commands that are used with HP 8116A are listed in Table 4 8 Information on how to change Models 8550 and 8551 settings from normal GPIB programming to HP programming mode is given in paragraph 4 16 Operating Instructions 3 19 This page intentionally left blank 3 20 Operating Instructions GPIB Operation Section 4 4 1 INTRODUCTION The GPIB general purpose interface bus is an instrumentation data bus with standards originally adopted by the IEEE Institute of Electrical and Electronic Engineering in 1975 and given the IEEE 488 designation In November 1987 the IEEE 488 document was revised primarily for editorial classi fication and addendum and the new document was identified as IEEE 488 1978 This document has been the standard for gen eral purpose instrumentation bus GPIB which has been adopted by worldwide instrumentation manu facturers In June 1987 the IEEE approved a new standard for programmable instruments and devices IEEE Standard 488 2 1987 Code
140. equence This allows variable length data words to be transmitted easily IFC Interface Clear The IFC command is sent to clear the bus and set hand shake lines to a known state Although device configurations differ the IFC command usually places instruments in the talk and listen idle states ATN Attention The controller sends ATN while transmitting addresses or multiline commands De vice dependent commands are sent with the ATN line high false SRQ Service Request The SRQ command is asserted by an external device when it requires service from the controller If more than one device is present a serial polling sequence as described in paragraph 4 8 2 must be used to determine which has requested service 4 8 2 Universal Multiline Commands Universal commands are multiline commands that require no addressing All instrumentation equipped to implement the command will do so simultaneously when the command is transmitted over the bus As with all commands the universal commands are sent over the data lines with ATN set low LLO Local Lockout The LLO command is sent by the controller to remove the Model 8550 from the local operating mode Once the unit receives the LLO command all its front panel controls except Power will be inoperative NOTE The REN bus line must be true before the instrument will respond to an LLO command To lock out the front panel controls of the Model 8550 the control
141. equently modifies front panel set up to its factory default The function of DCL is described in details in paragraph 3 5 3 2 1 3 Main Parameters Model 8550 There are four MAIN PARAMETERS push buttons which are used to modify the displayed reading Each time a button is depressed a different parameter is displayed The selected parameter is indicated by an LED Each row of LEDs is associated with a specific operating mode The parameters in the fol lowing may be displayed and modified Table 3 2 lists the limits for each of the above parameters 1 FUNCTION FREQ Frequency of the selected output wave form Frequency is defined for repetitive signals only When the function generator is set to operate in Operating Instructions 3 1 triggered mode the programmed frequency value has no effect on the output In gated mode the frequency defines the repetition rate within the gating signal In sweep mode the programmed value defines the sweep start point The programmed frequency retains its value at both SYNC and the main output connectors The frequency parameter may be pro grammed within the range of 10 00mHz to 50 00MHz Preset value is set to 1 000KHz AMPL Amplitude of the selected waveform at the main output connector The output signal is driven from a 500 source therefore the value of the amplitude parameter is specified and accurately controlled only when the output is terminated with 500 If the signal from the ou
142. er parsing 4 10 GPIB Operation 4 9 2 Separator Functional Element Summary The various elements within the Program Message are separated by ASCII characters that were specially assigned for this purpose These separators are discussed in the following paragraphs 4 9 2 1 Program Message Unit Separator The Program Message Unit gt separates sequential Program Message Unit elements from one another within a Program Message The Pro gram Message Unit Separator gt is defined as 3 It is allowed to use leading white space elements before the Program Message Separator gt White Space is defined as a single ASCll encoded byte in the range of 00 09 08 20 This range includes the ASCII control characters and the space but excludes the new line 4 9 2 2 Program Data Separator The Program Data Separator gt separates sequential Program Data elements from one another after a Command Program Header or Query Program Header It is used when a Command Program Header or Query Program Header has multiple parameters The Program Data Separator gt is defined as Preceding and succeeding White Space elements are permitted 4 9 2 3 Program Header Separator The Program Header Separator gt separates the Command Program Header or Query Program Header from the Program Data elements The Program Header gt is defined as white sp
143. ernal reference Model 8551 locks on the external reference signal regardless of its programmed fre quency setting After the generator has locked on the signal the user may generate a phase offset between the external signal and the signal at the output connector Offset range is 180 The generator is placed in its phase locking operating mode when the light behind PLL illuminates The phase locking operating mode can not be op erated in conjunction with the triggered modes To operate the instrument in its PLL operating mode proceed as follows 1 Depress the POWER switch once to turn the power on 2 Depress the operating mode push buttons until the light behind PLL illuminates 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Connect a BNC cable from the reference source to the front panel REF INPUT connector Use a T connector and connect the reference signal to channel A on an oscilloscope 5 Connect a BNC cable from 8551 output to channel B on the oscilloscope 6 Set osciloscope and observe that the two signals have the same frequency and are locked on the same phase 3 13A 4 1 Generating Phase Offsets As discussed in paragraph 3 12A 4 the generator is capable of generating phase offsets between the 3 14 Operating Instructions external reference signal and the main output con nector To generate phase offset proceed as follows 1 Repeat the operating instruction as i
144. erpreting the failure list is described in Section 5 3 11 REVIEWING THE AUTO CALIBRATION FAILURE LIST As discussed above if the auto calibration fails to successfully complete the instrument automatically generates a failure list The operator can review this list either immediately after the auto calibration proc ess or anytime later provided however that a sub sequent calibration process did not remove one the previously generated errors If the auto calibration completes without detecting a calibration error no failure list is generated and the function generator resumes normal operation If a calibration error is detected the generator starts displaying a message as described in paragraph 3 8 5 To terminate this display message and to exit from the failure evaluation process depress any front panel push button To evaluate the complete failure list depress the FAIL LIST 1 or the FAIL LIST J push buttons The blinking LED and the associated displayed digit indicates where the instrument has some difficulties to calibrate itself To recall the last saved failure list depress the 2nd and the FAIL LIST J push buttons in sequence and observe that the instrument displays the message 3 10 Operating Instructions as described in paragraph 3 8 5 Commence with the evaluation using the same procedure as was described above 3 12 MODIFYING PARAMETERS There are various parameters such as frequency and amplitude
145. expressed in a non decimal format String Response Data data type suitable for sending 7 bit ASCII character strings where the content needs to be Hidden by delimiters This element is generally used to send data for direct display on a device Definite Length Arbitrary Block Response Data A data type suitable for sending blocks of arbitrary 8 bit information when the length is known beforehand Indefinite Length Arbitrary Block Response Data A data type suitable for sending blocks of arbitrary 8 bit information when the length is not known beforehand or when computing the length beforehand is undesirable Arbitrary ASCII Response data A data type suitable for sending arbitrary ASCII data bytes when alternate data types are unworkable 4 11 2 Separator Functional Element Summary The various elements within the Response Mes sage are separated by ASCII characters that were specially assigned for this purpose These separators are discussed in the following paragraphs 4 11 2 1 Response Message Unit Separator The Response Message Unit Separator gt separates sequential Response Message Unit elements from one another when multiple Response Message Unit elements are sent in a Response Message The Response Message Unit Separator gt is defined as 4 11 2 2 Response Data Separator The Response Data Separator separates sequential Response Data elements from one another when mul
146. f additional display messages asso ciated with IEEE 488 2 programming These mes sages are discussed in section 4 of this manual 3 7 DETECTING PROGRAMMING ERRORS Model 8550 is a product of many years of experience and complete understanding of human engineering requirements A great deal of time was devoted during its design stage to simplify front panel pro gramming procedures thereby minimizing the poten tial of programming errors It is impossible however for an inexperienced operator to completely avoid programming errors For such cases the function generator employs a built in error detection mecha nism which warns against programming errors There are several error indications that may occur due to incorrect front panel programming procedures The indications are either visible error messages or audible beeping sound The audible alarm sounds while attempting an incorrect front panel programming sequence For instance an attempt to program an offset which exceeds the level window limits is a cause for such an alarm The alarm sound as long as the conditions remain false Other error conditions which may cause an audible alarm are discussed in different parts of this manual Front panel programming errors are normally in dicated by an audible alarm GPIB errors are detected automatically and are screened for a service request poll These indications are described in the following paragraphs 3 8 FRONT PANEL ERROR
147. failure ensures proper operation of the generator If self calibration failure was encountered the instrument first needs to be serviced and the source of failure removed Instructions how to self calibrate the gen erator is given in paragraph 3 10 5 8 2 Warm Up Period Most equipment is subject to at least a small amount of drift when it is first turned on To ensure accuracy turn on the power to the Model 8550 and allow it to warm up for at least 30 minutes before beginning the performance tests procedure 5 8 3 Front Panel Settings To avoid confusion as to front panel settings it is required that front panel set up be reset to factory default values at the beginning of each of the performance tests To reset front panel to factory default values depress 2nd and then DCL push buttons 5 8 4 Recommended Test Equipment Recommended test equipment for troubleshooting calibration and performance checking is listed in table 5 2 Test instruments other than those listed may be used only if their specifications equal or exceed the required characteristics 5 9 PERFORMANCE CHECKS PROCEDURE Accuracy specifications 3 of full scale up to 50 00MHz Equipment Counter 1 Set 8550 as follows CONTROL POSITION Trigger Mode Gated Trigger Level 10 V Output Squarewave 2 Set counter to frequency measurement 3 Connect 8550 output to counter input Set 8550 frequency and verify counter frequency reading as fo
148. fect on external signals having a high slew rate such as square waves The trigger phase offset parameter may be programmed within the range of 90 Preset value is set to 0 3 2 1 4 Trigger Mode Two push buttons are grouped in the TRIGGER MODE section Selection of one of the trigger modes is done by depressing one of these buttons The selected mode is indicated by an LED Model 8550 may be triggered from either one of the following Sources 3 4 Operating Instructions 1 External signal which may be applied to the TRIG REF IN connector 2 An internal asynchronous trigger generator 3 GPIB commands like GET or TRG 4 Front panel MANual push button The MANual trigger is active when the instrument set to operate in one of its external trigger modes This push button when depressed serves as a re placement for an external trigger source 3 2 1 5 Control There is one push button in the MOD group This button is used to select an external modulation control for the function generator The selected control mode is indicated by an LED 3 4 1 6 Output There are two push buttons in the OUTPUT group These buttons are used for selecting an output waveforms for the output connector The selected function is indicated by an LED Note The Model 8550 powers up with its output in stand by state You have to press one of the two push buttons in the OUTPUT group to remove the Model 8550 from stand by 3 4 1 7
149. first having sent a complete Query Message including the lt Program Message Terminator gt to the device In the event of Unterminated Action model 8550 performs the following steps 1 Sets the Query Error bit in the Standard Event Status Register 2 Clears the output queue 3 Sets brq False If a read sequence is interrupted by a new lt Program Message gt before it finishes sending a lt Response 4 22 GPIB Operation Message gt model 8550 executes an Interrupted Action GPIB bus response is similar to the Un terminated Action The reading sequence is conducted as follows The controller sets the ATN line true The Model 8550 is addressed to talk The controller sets ATN false The instrument sends the information string over the bus one byte at a time 5 The controller recognizes that the string is terminated 6 The controller sets the ATN line true 7 The UNT untalk command is placed on the bus by the controller gt 4 12 1 Interrogate Parameter Data Query The interrogate parameter data query allows access to information concerning present operating conditions of the instrument When the interrogate parameter data query is given the Model 8550 will transmit appropriate data string information the next time the instrument is addressed to talk Model 8550 Inter rogate Parameter Data Query include FRQ Interrogate output frequency parameter AMP Interrogate
150. g one of the above sweep directions is described in the following The same procedure is used for both linear and logarithmic sweep scales 1 Depress the 2nd push button and observe that the display is modified to indicate the following 2nd 3 12 Operating Instructions appears flashing 2 Depress the SWP MODE push button in the MAIN group and observe that one of the following read outs is displayed UP dn U d or d U This reading indicates the selected sweep mode To modify the selected sweep mode to your desired modes depress the x1 modifier push button until the selected mode is displayed 3 Depress the EXE push button The output waveform now sweeps with the selected sweep mode 3 13 3 Phase Locking Generator Operating Mode Model 8550 Model 8550 employs an automatic locking circuit which enables phase and frequency locking to an external reference Model 8550 locks on the external reference signal regardless of its programmed fre quency setting After the generator has locked on the signal the user may generate a phase offset between the external signal and the signal at the output connector Offset range is 180 The generator is placed in its phase locking operating mode when the light behind PLL illuminates The phase locking operating mode can not be operated in conjunction with the triggered modes To operate the instrument in its PLL operating mode proceed as follows 1 Depress the
151. he amplitude circuits The 8 bits of the FSB contain information about calibration failures in the offset phase lock loop trigger phase offset and burst circuits The 16 bits of the FSC contain infor mation about calibration failures in the pulse width generator and the rise fall time control circuits The summary messages from these registers are fed to the Status Byte register and can be monitored and reported back to the user upon request The Calibration Failure Status Registers are destructively read with the FSA FSB and FSC queries The response to this query is a number that represents the sum of the binary weighted value of the Calibration Failure Status Register The Calibration Failure Status Registers are cleared by a CLS common command and when read by FSA FSB and FSC Power off does not clear these registers Description of the various calibration failures is given in the troubleshoot ing section of this manual Figure 4 4 Calibration failure Status Registers Interpretation Not Amplitude Errors Frequency Errors Used 5 4 3 2 1 9 8 7 6 5 4 3 2 1 15 14 13 12 11 10 9 5432100 FSA Burst Trig Ph PhaseLock Offset 1 2 1 3 2 112 1 76543210 FSB Not Rise Fall Times Errors Pulse Width Errors Used 6 5 4 3 2 118 7 6 5 4 3 2 1 15 14 13 12 11 10 9 8 51413121110 FSC 4 28 GPIB
152. heir limits Programming amplitude levels with values outside their limits Same as LEVEL ERROR except HIL LOL window is active Timing error Programming Error Syntax Error System Failure Not used in 8550 8551 Autovernier in process Sweep in process Model 8550 only Service request Buffer not empty Not used in 8550 8551 be used in combination with delimiters For example the following com mand will result in an error message FRQ 1 000E 3KHZ Use either engineering notation or delimiters only The following two examples are legal FRQ 1 000E 6 FRQ 1 000 MHZ GPIB Operation 4 33 This page intentionally left blank 4 34 GPIB Operation Maintenance amp Performance Tests Section 5 5 1 INTRODUCTION This section provides maintenance service informa tion and performance tests for the models 8550 and 8551 Fuse replacement procedure line voltage se lection and disassembly procedure are also included WARNING The procedures described in this sec tion are for use only by qualified service personnel Do not perform these procedures unless qualified to do so Many of the steps covered in this section may expose the indi vidual to potentially lethal voltages that could result in personal injury or death if normal safety precautions are not observed 5 2 LINE VOLTAGE SELECTION The Model 8550 may be operated from either 115 Vac or 230 Vac nominal 50 60 Hz power sources A special tran
153. ic representations as de fined in ANSI X3 42 1975 NR1 NR2 and NR3 A Decimal Numeric Response Data elements are defined as 1 NR1 elements consists of a set of implicit point representations of numeric values i e 12345 2 NR2 elements are the representations of explicit point numeric values i e 12 345 3 NR3 elements are representations of scaled explicit radix point numeric values together with an exponent notation i e 123 456E 3 4 12 READING FROM THE MODEL 8550 The reading sequence is used to obtain from Model 8550 various Response Message Units such as frequency amplitude offset or operating modes The Response Message Unit elements are placed in an output queue The output queue may be read by device defined queries Such device defined que ries cause the item read to be removed from the output queue Model 8550 executes the Program Message elements in the order received The output is cleared when any of the following occur 1 Reading all the items in the output queue Upon receipt of a new Program Message Upon receipt of the CLS DCL or SDC com mands 4 Upon Power on IEEE 488 2 specifies that a device cannot send lt Response Message gt elements unless commanded to do so This is specified as an Unterminated Action The Unterminated Action is executed when the controller attempts to read a lt Response Mes sage gt from the device without
154. ich generate the ramp 6 8 3 Ramp Generator Circuit The ramp generator circuit generates the ramp wave form which is then made available at the 8551 output connector The negative going ramp waveform is derived from the monostable circuit by discharging a timing capacitor This ramp is buffered by Q28 and routed to the ramp amplifier input U21 An offset correcting voltage is summed to the same input through R68 and additional compensating voltage through R84 The positive going ramp at the output of U21 is inverted by an operational amplifier U19 and resistors R64 and R65 The selection of positive or negative going ramp to the output amplifier board is made by a relay K2 6 8 4 Transition Times Generator Circuit The transition times generator control the rise and fall times of the generated pulses at the 8551 output connector In general the variable rise and fall times are generated by charging and discharging a selected timing capacitor with a known level of current gen erating a positive and negative going linear voltage ramps The currents for the transition times generator will be discussed in paragraph 6 8 5 Emitter coupled current switches Q22 Q24 Q23 and Q25 alternately switch the required current to a selected timing capacitor C1 C2 C3 C9 and C10 This generates a positive and consequently negative voltage ramps on the capacitors The positive going ramp is limited to 1 5 V by a circuit made of U1b Q2 and th
155. iety of parameter information related to the lt Program Header gt 4 9 6 1 Character Program Data The lt Character Program Data gt functional element is not implemented in Model 8550 Therefore it shall not be discussed in this manual 4 9 6 2 Decimal Numeric Program Data The lt Decimal Numeric Program Data gt is a flexible version of the three numeric representations as de fined in ANSI X3 42 1975 NR1 NR2 and NR3 A Decimal Numeric Program Data elements are defined as 1 NR1 elements consists of a set of implicit point representations of numeric values i e 12345 2 NR2 elements are the representations of explicit point numeric values i e 12 345 3 NR3 elements are representations of scaled explicit radix point numeric values together with an exponent notation i e 123 456 3 4 9 6 3 Suffix Program Data A Suffix Program Data element permits the use of a suffix following the Decimal Numeric Program Data NRf The suffix expression associated units and optional multipliers that modify how the GPIB Operation 4 11 is interpreted by the device The presence of a Suffix Program Data after an NRf is always optional No particular Command Program Header or Query Program Header is a device shall require the use of a Suffix Program Data element 4 9 6 4 Non Decimal Numeric Program Data The Non Decimal Program Data functional element is not impl
156. ig Per 5 00 ms 2 Connect 8550 output to the oscilloscope input and set oscilloscope input impedance to 500 3 Set vertical sensitivity on the oscilloscope to 0 2V per division Set oscilloscope time base and observe that the 8550 output is displayed within exactly 6 vertical divisions 4 Change 8550 Start Trigger Phase Offset to 90 and observe that the base line is shifted to the bottom of the sinewave creating an haversine wave form Observe that the base line is at the 3 division line 1 small grid lines 5 Change 8550 Start Trigger Phase Offset to 90 and observe that the base line is shifted to the top of the sinewave creating an inverted haversine wave form Observe that the base line is at the 3 division line 1 small grid lines 5 9 12 Phase Lock Loop Characteristics Accuracy specifications 3 3 of reading from 10Hz to 100 0 KHz Equipment Counter pulse function generator syn thesizer 50Q feedthrough termination 500 T BNC connector regular BNC connector 1 Set 8550 as follows Output Waveform Squarewave Display Modify P Offset 2 Connect test set up as described in Figure 5 1 3 Set external pulse function generator period to 100ms and duty cycle to 50 4 Set counter to Phase A to B function trigger level A and B to 1 00 V slope A and slope B to negative 5 Set 8550 PLL phase offset and verify the following accuracy requirements 8550 SETTING COUNTER PHASE READ
157. ime base and adjust R91 for best pulse flatness 9 Change 8550 8551 frequency setting to 1 000 KHz and readjust R91 for best flatness in this range 10 Repeat steps 8 and 9 until best result is obtained in both steps 11 Change Model 8550 8551 frequency setting to 50 00 MHz 12 Set oscilloscope vertical gain and time base and select R13 for best horizontal pulse symmetry 7 3 4 Pulse Width Adjustment Model 8551 Equipment Oscilloscope OSCILLOSCOPE CHAN CHAN CHAN CHAN 2 3 4 2008 ATTEN ATOR Figure 7 3 Connection Squarewave Response Adjustment Adjustments and Troubleshooting 7 3 Figure 7 4 Connection Pulsewidth Ramp Adjustment MODEL 8081 STATE y 1 Change 8551 operating mode setting to pulse mode period to 100 0 ns pulse width to 10 0 ns and output waveform to squarewave 2 Connect 8551 output to oscilloscope input as shown in Figure 7 4 Set oscilloscope input impedance setting to 500 3 Set oscilloscope vertical gain and time base and adjust trimmer R100 on the pulse generator board to get a 10 0 ns 1 ns reading on the oscilloscope 7 3 5 Ramp Base Line Adjustment Model 8551 Equipment Oscilloscope 1 Leave Model 8551 connected to the oscilloscope as was shown in Figure 7 4 Change Model 8551 output setting to ramp MOOEL 80 81 ETATE MAIN PARAMETERS TRIGGER OUTP
158. imer repeatedly generates a single output cycle Gated External signal enables generator First output cycle synchronous with the active slope of the triggering signal Last cycle of output waveform always completed Burst Preset number of cycles 1 4000 stimulated by an internal external or manual trigger Internal Burst An internal timer repeatedly generates a burst of counted output cycles Trigger Frequency External To 50MHz Internal From 20us to 999s Manual Simulates an external trigger signal Start Phase Offset Adjustable from 90 to 90 to 500 0KHz proportionally reduced from 500 1KHz to 50 00MHz Accuracy 3 to 500 0KHz Trigger Level variable 10 0V to 10 0V 1 4 General Information Table 1 1 Model 8550 8551 Specifications continued LOGARITHMIC SWEEP CHARACTERISTICS Modes Auto Triggered Gated and Burst Output frequency repeatedly changes from start sweep to stop sweep settings Available sweep directions are up down up down and down up Width 10 decades maximum Rate per Decade Continuously adjustable from 10mS to 9995 NOMINAL per decade Steps per decade Depends on sweep time and range Automatically adjusted for maximum steps per sweep time Maximum steps are 200 minimum steps are 50 Sweep Output 1V decade below 5 decades 5V decade above 5 decades Marker Output 5V with no marker drops to NOMINAL when marker frequency is reached and remains
159. ion and externally controlled modes such as PWM VCO and AM may operate in conjunction with the pulse generator operating mode Access to the DUTY parameter is automatically inhibited by the generator 3 13A 3 Pulse Generator With Fixed Duty Cycle Operating Mode Model 8551 Some applications require that the ratio between the pulse width to the pulse period remain constant regardless of the programmed period The pulse generator with fixed duty cycle operating mode is a special case of the normal pulse generator which provides control over the duty cycle rather than the pulse width In this mode the user should only program the required duty cycle Then while changing Operating Instructions 3 13 the period the instrument automatically adjusts the duty cycle ratio at the output connector The duty cycle may be selected within the range of 196 to 855096 however this range may be extended to almost 9996 by using the pulse com plement function The generator is placed in its fixed duty cycle operating mode when the light behind F DTY illumi nates Triggered operation and externally controlled modes such as PWM VCO and AM may operate in conjunction with the pulse generator operating mode Access to the WIDTH parameter is automat ically inhibited by the generator 3 13A 4 Phase Locking Generator Operating Mode Model 8551 Model 8551 employs an automatic locking circuit which enables phase and frequency locking to an ext
160. irected below If you have any questions contact your local Tabor field engi neering representative or the Tabor Service Depart ment at the factory If the original Tabor supplied packaging is to be used proceed as follows 3 Mark the carton with the model number and serial number with indelible marking If it is to be shipped show sending address and return address spaces with rubberized hair or cellular plastic cush on two sides of the box cover all previous shipping ioning material Close box in accordance with con labels tainer specifications Seal with sturdy water resistant tape or metal straps 429 0 395 0 Figure 2 2 Model 8550 8551 Outline Dimensions Preparation 2 3 7 Mark container DELICATE INSTRUMENT work authorization order as well as FRAGILE etc Mark instrument model and serial the date and method of shipment number and date of packaging Affix shipping labels ALWAYS OBTAIN A RETURN as required or mark according to MIL STD 129 AUTHORIZATION NUMBER FROM THE FACTORY BEFORE SHIPPING THE INSTRUMENT TO Tabor NOTE If the instrument is to be shipped to 2 12 SAFETY Tabor for calibration or repair attach a tag to the instrument identifying Be fully acquainted and knowledgeable with all as
161. is only active when sweep mode is on 3 4 POWER UP PROCEDURE The basic procedure of powering up the Model 8550 is described below 1 Connect the female end of the power cord to the AC mains receptacle on the rear panel Connect the other end of the power cord to a grounded AC outlet WARNING Be sure the power line voltage agrees with the indicated value on the rear panel of the instrument Failure to heed this warning may result in in strument damage 3 6 Operating Instructions The instrument is equipped with a 3 wire power cord designed to be used with grounded outlets When the proper connections are made the instrument chassis is connected to the power line ground Failure to use a properly grounded outlet may result in personal shock hazard 2 Turn on the mains power by pressing and releasing the POWER switch on the front panel 3 The instrument then begins operation by per forming a display and indicator test which takes approximately one second All front panel indicators turn on and the display appears as follows 8 8 8 8 8 4 To verify that all display segments are operating compare the instrument s display with the above during the test 5 After all the indicators are tested the instrument performs ROM and RAM tests Successful execution of these tests is followed by a one second read out of the installed software revision similar to the example below 501 0 6 Following the software revisio
162. ith model 8551 In other words one can remove HP s model 8116A from ATE system rack and replace it with the Tabor 8550 8551 without the need to modify the existing test software A list of device dependent command which is being used by the HP mode 8116A is given in the following Listed are those commands that have equivalent functions in the Model 8550 For complete description of the various commands refer to Table 3 3 Mode Parameter Messages listen function in the HP manual To modify 8551 device dependent command set to com ply with model 8116A proceed with the following steps 1 Depress the 2nd push button once then depress the GPIB ADR push button The display will be modified to display the following GPxx Where x may be any number from 0 to 30 2 Depress MODIFIER x100 1 push button once The displayed reading will change as follows HPxx Indicating that model 8551 s device dependent command set is made fully compatible with HP s model 8116A device dependent command set De pressing the MODIFIER x100 1 or x100 J push buttons toggles between GPIB and HPIB compatibility options To modify the GPIB address proceed with the procedure given in paragraph 4 7 3 To store the required compatibility option de press EXE The instrument then resumes normal operation Program Header V M CT Progran Data gt 01 1 0 L S F D X 2 0 1 0 0 0 0 0 Status given after IEEE 488 1 DCL or SD
163. ition in pulse complement mode The width parameter is common to the pulse and the ramp waveforms It is convenient to interpret the displayed and specified value as that obtained with the fastest edges However In linear transition mode the displayed and specified value is that obtained at the turning point of the pulse edges The pulse width parameter may be programmed within the range of 10 0ns to 999ms The ramp width parameter may be programmed within the range of 5 00us to 999ms Preset value is set for both the pulse width and the ramp width to 100 DUTY The DUTY parameter specifies the duty cycle of either the pulse output or the ramp output when the Model 8551 is set to operate in its fixed duty cycle mode The duty cycle parameter may be programmed within the range of 1 to 855096 Preset value is set 50 3 TRANSITION LEAD The LEAD parameter specifies the time interval between the 1096 to 9096 amplitude points on the leading edge The leading edge value may only be selected when the pulse function generator is set to operate in its linear transition mode oth erwise the leading edge transition time is set to its fastest position The leading edge transition time Operating Instructions 3 3 parameter may be programmed within the range of 8ns to 99 9ms Preset value is set 10 0 5 TRAIL The TRAIL parameter specifies the time interval between the 1096 to 9096 amplitude points on the trailing edge The trailing e
164. iving circuit FAIL 6 Check C32 Q31 and their driving circuit 7 Check C37 Q30 and their driving circuit 8 Check C36 Q34 and their driving circuit 7 5 8 Rise Fall Time Calibration Failures Model 8551 Failures in the rise fall time circuit is indicated by a blinking LEAD or TRAIL indicator with an associated displayed readout In general rise fall time failures may generate as a result of faults in the pulse generator or in the main boards The following is a Adjustments and Troubleshooting 7 7 list of possible rise fall time calibration failures Pos sible solutions to remove the source of these errors are suggested If FAIL 1 through FAIL 6 were detected refer first to the theory of operation section and verify proper operation of the following circuits on the pulse generator board rise fall time current generator rise fall time generator and rise fall time output buffer on the pulse width board Also verify proper operation of the rise fall time reference control on the main board For other failures proceed with the following list All of the following tests are performed on the pulse width board FAIL 1 Check C10 K1 and their associated components FAIL 2 Check C9 K1 Q7 and their associated components FAIL 3 Check C4 FAIL 4 Check C3 Q6 and their driving circuit FAIL 5 Check C2 Q3 and their driving circuit FAIL 6 Check C1 Q5 and their driving circuit 7 6 GENRAL TROUBLESHOOTING HIN
165. l marked with Or e Dont plug in the power cord until directed to by the installation instructions e Don t repair the instrument unless you are qualified electronics technician and know how to work with hazardous voltages Pay attention to the WARNING statements They point out situations that can cause injury or death Pay attention to the CAUTION statements They point out situations that can cause equipment damage The American National Standard Institute ANSI states that a shock hazard exists when voltage levels greater than 30V RMS 42 4V peak 60 VDC are present A good safety practice is to expect that hazardous voltage is present in any unknown circuit before touching or disconnecting the line cord Before operating this instrument make sure the line cord is connected to a properly grounded power receptacle Inspect the connecting cables and test leads for possible wear cracks or breaks before each use For maximum safety do not touch the product test cables or any other of the instrument parts while power is applied to the circuit under test ALWAYS remove power from the entire test system before connecting cables or jumpers or making internal changes Do not touch any object that could provide a current path to the common side of the circuit under test or power line earth ground Always keep dry hands while handling the instrument If you are using test fixtures keep the lid closed while power is applied to th
166. l pulse generator connected to the 8550 for the next test 5 9 8 3 External Burst 1 Set 8550 as follows Maintenance And Performance Tests Page 5 5 CONTROL POSITION Frequency 1 000 MHz Trigger Mode BURST 2 Set oscilloscope and verify on the oscilloscope that 8550 outputs a burst of two complete output waveforms Remove external pulse generator con nection from the 8550 for the next test 5 9 9 Internal Trigger Burst Characteristics Specifications Triggered An internal timer repeat edly generates a single output waveform Burst An internal timer repeatedly generates a burst of pre selected number of cycles Equipment Oscilloscope 5 9 9 1 Internal Trigger 1 Set 8550 as follows CONTROL POSITION Frequency 10 00 KHz Trigger Mode TRIG D Int Trig Per 1 ms 2 Set 8550 to Internal Trigger mode by depressing 2nd and INT TRG push buttons in sequence 3 Set oscilloscope and verify on the oscilloscope that 8550 outputs repetitive triggered waveform 5 9 9 2 Internal Burst 1 Set 8550 as follows Frequency 10 00 Hz Trigger Mode TRIG D 2 Connect 8550 output to the oscilloscope input Set oscilloscope time base to 1 ms 3 Depress a few times the MANUAL push button and verify that you get a single sinewave waveform on the oscilloscope every time that the MANUAL push button is depressed Leave 8550 output con nected to the oscilloscope for the next test 5 9 10 2 Manual Gate 1 Set 8550
167. ler must perform the following steps 1 Set ATN true 2 Send the LLO command to the instrument DCL Device Clear The DCL command may be used to clear the Model 8550 setting it to a known state Note that all devices on the bus equipped to respond to a DCL will do so simulta neously When the Model 8550 receives a DCL command it will return to the default conditions listed in Table 4 4 Factory pre selected parameters are listed in Table 3 1 To send a DCL command the controller must perform the following steps 1 Set ATN true 2 Place the DCL command on the bus SPE Serial Poll Enable The serial polling sequence is used to obtain the Model 8550 status byte Usually the serial polling sequence is used to determine which of several devices has requested service over the SRQ line However the serial polling sequence may be used at any time to obtain the status byte from the Model 8550 For more information on status byte format refer to paragraph 4 14 The serial polling sequence is conducted as follows 1 The controller sets the ATN line true 2 The SPE Serial Poll Enable command is placed on the bus by the controller 3 The Model 8550 is addressed to talk 4 The controller sets ATN false 5 The Model 8550 then places its status byte on the bus to be read by the controller 6 The controller then sets the ATN line low and places SPD Serial Poll Disable on the bus to end the serial polling sequence Step
168. libration Failures Failures in the offset generation circuits are indicated by a blinking OFST indicator with an associated displayed readout In general offset failures may generate as a result of faults in the calibration output amplifier and main boards The following is a list of possible offset calibration failures Possible solutions to remove the source of these errors are suggested FAIL 1 Check the offset compensation circuit U11 012 013 and their associated components on the main board Check the preamplifier circuit U9 resistor R38 and their associated components on the output amplifier board FAIL 2 Check the offset generator circuit U23 U24 U29 and their associated compo nents on the output amplifier board Check U8 Q14 R73 R82 and R83 on the output amplifier board 7 5 4 Phase Lock Offset Calibration Failures Failures in the phase locking circuits are indicated by a blinking P OFST indicator with an associated displayed readout In general phase lock offset failures may generate as a result of faults in the calibration and the CPU boards The following is a list of possible phase lock offset calibration failures Possible solutions to remove the source of these errors are suggested FAIL 1 Check the signal selector circuit to the phase lock detector Uxx and its associ ating components on the calibration board Check the PLL detector Uxx on the cali bration board Check the trigger input
169. limited to 30 3 19 2 Recalling Set ups Level Amplitude Window Range 8 00V 100mV to 16 0V 800 10mV to 99 9mV Offset Range OV to 7 95V OV to 795mV Tabel 3 3 Offset Amplitude Programming Limits 3 18 Operating Instructions The Model 8550 8551 employs non volatile memory RAM The computer circuit continuously monitors front panel traffic and saves it in a special location within the RAM This location is separated from the stored front panel set ups After turning AC MAINS off or in case of an accidental power failure the generator updates front panel indicators with the last set up before power shut down To recall a stored front panel set up proceed as follows 1 Depress the 2nd and RECALL push button in sequence and observe that the display is modified to indicate the following C xx 2 appears blinking C means that the instrument is placed in memory recall mode indicates the number of the present storage cel Numbers may range from 00 to 30 Depressing any other push button removes the gen erator from the memory recall mode and leaves front panel settings unchanged 2 Recalling a specific front panel set up is done by depressing the MODIFIER x1 1 or x1 until the desired cell number is displayed Depressing EXE updates front panel set up with the parameters which were stored in the selected memory cell 3 Repeat the above procedure for as many set ups
170. lity of bus hang up some controllers have time out routines to display error messages if the handshake sequence stops for any reason Once the NRFD and NDAC lines are properly set the source sets the DAV line low indicating that data on the bus is now valid the NRFD line then goes low the NDAC line goes high once all devices on the bus have accepted the data Each device will release the NDAC line at its own rate but the NDAC line will not go high until the slowest device has accepted the data byte After the NDAC line goes high the source then sets the DAV line high to indicate that the data on the bus is no longer valid At this point the NDAC line returns to its low state Finally the NRFD line is released by each of the devices at their own GPIB Operation 4 3 rates until the NRFD line finally goes high when the slowest device is ready and the bus is set to repeat the sequence with the next data byte The sequence just described is used to transfer both data and multiline command The state of the ATN line determines whether the data bus contains data or commands 4 3 3 Data Lines The IEEE 488 2 bus uses the eight data lines that allow data to be transmitted and received in a bit parallel byte serial manner These eight lines use the convention DIO1 through 0108 instead of the more common DO through D7 binary terminology The data lines are bi directional and as with the remaining bus signal lines low is true
171. llowing SREO mask SRE1 Service request on pulse ramp error SRE2 Service request on FSC SRE4 Service request on FSB SRE6 Service request on FSA SRE16 Service request on MAV SRE32 Service request on ESB SRE128 Not used 4 14 2 Standard Event Status Register ESR The Standard Event Status Register is a special application of the status reporting IEEE 488 2 docu ment specifies the meaning of each bit of this register The 8 bits of the SESR have been defined by the IEEE 488 2 as specific conditions which can be monitored and reported back to the user upon request The Standard Event Status Register is destruc tively read with the ESR common query The Standard Event Status Register is cleared by a CLS common command on power on and when read by ESR The arrangement of the various bits within the register is firm and is required by all GPIB instruments that implement the IEEE 488 2 Description of the various bits is given in the following Bit 0 Operation Complete Generated in re sponse to the OPC command It indicates that the device has completed all selected and pending op erations and is ready for a new command Bit 1 Request Control This bit operation is disabled on model 8550 Bit 2 Query Error This bit indicates that an attempt is being made to read data from the output queue when no output is either present or pending Bit 3 Device Dependent Error This
172. llows 8550 SETTING COUNTER READING 5 000 Hz 4 850 Hz 5150 Hz 50 00 Hz 48 50 Hz 51 50 Hz 500 0 Hz 485 0 Hz 515 0 Hz 5 000 KHz 4 850 KHz 5 150 KHz 50 00 KHz 48 50 KHz 51 50 KHz 500 0 KHz 485 0 KHz 515 0 KHz 5 000 MHz 4 850 MHz 5 150 MHz 10 00 MHz 9 700 MHz 10 30 MHz 30 00 MHz 29 10 MHz 30 90 MHz 50 00 MHz 48 50 MHz 51 50 MHz If model 8551 is tested modify front panel FREQ setting to PER and proceed with the next two tests 8551 SETTING COUNTER READING 999 9 ms 970 0 ms 1 030 s 5 9 1 Frequency Accuracy Gated Mode 99 99 ms 97 00 ms 103 0 ms Table 5 2 Required Test Equipment Instrument Recommended Specifications Use Model Counter HP5334B 100MHz Universal DMM HP3478A 0 1V 100Vac rms DC Pulse Function Generator Tabor 8551 1mHz 20MHz P Synthesizer Marconi 2019 80KHz 1040MHz DC power supply Fluke 341A OV 30V 0 1 Oscilloscope Tek 2465B 400MHz band width Distortion analyser K H 6900 100Hz 1MHz HP 3588A 10KHz 350MHz P Feedthrough Termination Tek 011 0129 00 500 2W 0 1 2088 feedthrough Attenuator Tek 011 0086 00 500 2W 2 P AM detector Wavetek Datron D152 500 0 2 1000MHz P P Performance Test A Adjustments T Troubleshooting Maintenance And Performance Tests Page 5 3 5 9 2 Frequency Accuracy Continuous Mode Accuracy specifications 3 of full scale up to 999 9 mHz 0
173. lows 1 Depress the POWER switch once to turn the power on 2 Select the required output waveform and set up the output parameters to the required charac teristics 3 Modify internal trigger period PER to the required interval 4 Depress the TRIGGER MODE push button until the light behind TRIG D illuminates 5 Depress 2nd and then the MAN push buttons and observe that the I TRG light illuminates indicating that the internal trigger stimulant is now active 3 17 2 2 Counted Burst Mode When set to operate in internal counted burst mode the output connector generates a train of counted waveforms at programmable intervals Note that the programmed internal period should not exceed the period of the complete burst duration otherwise an Operating Instructions 3 17 error will result Model 8551 will indicate such errors with an ERROR LED To generate a counted burst using the internal period generator proceed exactly as described in paragraph 3 17 2 1 except select the BURST mode 3 17 3 Triggering The Function Generator With A Manual Stimulant The MAN button simulates an external signal If the generator is placed in GATED mode an output signal will be available as long as the MAN push button is depressed When the generator is set to TRIG D triggered mode each time the MAN button is depressed a single output waveform is generated When the Model 8550 8551 is set to generate a counted burst each time the
174. ltage to the 5 2 V supply 7 6 2 Digital Circuitry and Display Checks The most important section to be verified after the power supply checks is the digital section with its various clocks Problems with the digital circuitry could cause erratic operation or erroneous display readings Problems in the clock generator for the C P U and the digital circuit may cause a complete malfunction of the entire section The C P U would not even start generating the control lines This makes it impossible to troubleshoot the remaining of the circuits Check the various components associated with the digital circuitry clocks and the IEEE 488 interface using the information given in Table 7 3 Test results after selecting DCL T Depress and release once for each test Test Point Description Test Result U12 pin 13 CPU clock 10 MHz TTL level signal U6 pin 9 GPIB interface clock 5 MHz TTL level signal U6 pin 6 Display interface clock 1 25 MHz TTL level signal U6 pin 15 CPU timer clock 4 88 KHz TTL level signal U6 pin 1 Beeper clock 2 44 KHz TTL level signal 05 pin 30 ALE line 160ns TTL level positive going signal 05 pin 29 PSEN line 265ns TTL level negative going signal 05 pin 17 RD line 500ns TTL level negative going signal 05 pin 16 WR line 500ns TTL level negative going signal U14 pin 3 Accuracy control signal 1KHz 5096 duty cycle TTL level signal U14 pin 2 Control counter gate Period 300ms width 250ms T
175. m bers from 00 to 30 RST Reset Sets device dependent functions to a known state purges all DPC commands and queries and aborts all pending operations The output queue Service Request Enable Register Standard Event Status Enable Register and power on flag are not affected Device defaults are listed in Table 4 4 SAV Save Command allows the user to store the present state of a device in local memory If the device has more than memory location the command must be followed by a number to designate the storage register to be used Model 8550 may store settings in registers designated with numbers from 00 to 30 SRE Service Request Enable Command fol lowed by a number sets the Service Request Enable register which determines what bit in the status byte will cause a service request from the device The binary equivalent of the number represents the values of the individual bits of the Service Request Enable Register TRG Trigger Command has exactly the same effect as a GET when received parsed and executed by the device Wait to Continue Command causes device to wait until all previous commands and queries are completed before executing any which follow the command 4 10 10 1 Set ups SAV RCL The setups commands select the memory location where front panel setup is to be stored SAV or from where recalled FRCL To store or recall a setup use one of the following commands
176. mantissa and a single digit exponent The exponent uses a leading minus indicating negative values The sign on the exponent changes to for zero or positive values Operating Instructions 3 5 The display is also used to indicate other information such as messages 2 INDICATORS 35 indicators are located on the front panel Model 8551 These indicators are used as pointers to a selected parameter operating modes trigger modes etc 3 3 REAR PANEL FAMILIARIZATION 3 3 1 Connectors And Switches 1 AC RECEPTACLE Power is applied through the supplied power cord to the 3 terminal AC re ceptacle Note that the selected ac mains voltage is marked on the line voltage selector switch 2 LINE SWITCH The LINE VOLTAGE SELEC TOR switch selects one of the primary voltage which are marked on both sides of the switch 3 LINE FUSE The line fuse provides protection for the AC power line input For information on replacing this fuse refer to Section 5 4 IEEE 488 CONNECTOR This connector is used for connecting the instrument to the IEEE 488 bus 5 SWEEP OUT CONNECTOR This connector is used for connecting the instrument the X input on the oscilloscope Its output level is either fixed in linear sweep mode or proportional to the sweep time per decade in logarithmic sweep mode 6 MARKER OUTPUT CONNECTOR This con nector is used for connecting the function generator to the Z input on the oscilloscope This output
177. mary message is set to FALSE Methods of clearing the other auxiliary status registers are discussed in the following The RQS message in the Status Byte Register will be FALSE The use of the IEEE 488 1 DCL or SDC commands another method of clearing the Status Byte Register however in some cases it is not recommended to use this method since the entire front panel set up is reset to factory default values 4 14 1 4 Service Request Enable Register The Service Request Enabling Register is an 8 bit register that enables corresponding summary mes sages in the Status Byte Register Thus the appli cation programmer can select reasons for the model 8550 to issue a service request by altering the contents of the Service Request Enable Register The Service Request Enable Register is read with the SRE common query The response to this query is an number that represents the sum of the binary weighted value of the Service Request Enable Register The value of the unused bit 6 is always zero The Service Request Enable Register is written using the SRE common command followed by a Decimal Numeric Program Data element repre senting the bit values of the Register A bit value one indicates an enabled condition Consequently a bit value of zero indicates a disabled condition The Service Request Enable Register is cleared by send ing SREO The generator always ignores the value of bit 6 Summary of SRE messages is given in the fo
178. mp Error Status Register is given int the following When the pulse generator is set to operate in its triggered mode of operation the period time in the following formulas is replaced by the period of the internal trigger generator Error 1 Bit 0 This bit indicates that an error relating to the pulse width and the period have Figure 4 5 Ramp Pulse Errors Status String ERR Interpretation Pulse Ramp Errors Error No 8 7 6 5 4 3 2 Bit No 7 6 s5 4 3 2 1 0 occurred This error bit is set true under the following conditions Pulse Width gt 0 8 x Period Error 2 Bit 1 This bit indicates that an error relating to the pulse width and the period have occurred This error bit is set true under the following conditions Period Pulse Width 10 ns Error 3 Bit 2 This bit indicates that an error relating to the pulse width and the leading edge transition time have occurred This error bit is set true under the following conditions 1 25 x Rise Time Pulse Width Error 4 Bit 3 This bit indicates that an error relating to the pulse width the period and the trailing edge transition time have occurred This error bit is set true under the following conditions 1 25 x Fall Time Period Pulse Width NOTE When the model 8551 is placed is External Trigger mode errors 1 2 and 4 can not occur Error 5 Bit 4 This bit indicates that an error relating to the period Per coun
179. n modes for the Model 8550 8551 continuous mode triggered mode gated mode and counted burst mode Refer to the schematic diagrams at the end of this manual throughout the following description Detailed description of the various trigger modes is provided in the following paragraphs The trigger command is applied to the trigger circuit from the calibration board through J2 pin 12 to the gates in U23b U23c and U23d These gates shape and differentiate this signal and apply it to the reset input of U16a and U16b Continuous Mode In this mode U16a is always Set to its reset position Its output control the emitter coupled transistors Q24 and Q25 through diodes CR11 and CR12 The current from R104 flows through Q24 producing a positive voltage on the collector of Q24 which is then applied through the emitter follower Q23 to the cathode of the clamping diode CR10 CR10 is then negative biased and does not interfere with the VCO oscillations Triggered Mode In this mode the reset input to U16a is released The D input is kept at logic level 1 by Q26 A positive transition from the comparator U13 at the clock input to U16a sets U16a output to logic level 1 causing Q24 to turn off and forward biasing CR10 through the emitter follower Q23 clamping the triangle waveform to a certain voltage level A positive going transition of the triggering signal is differentiated by U23 R118 and C46 and applied to the reset input of U16a
180. n the status byte ESR Returns an which is the value of the Standard Event Status Enable Register SRE Sets the bits of the Service Request Enable Register Returns an which is the value of the Service Request Enable Register 4 14 STATUS BYTE REGISTER STB The Status Byte Register contains the device s STB and RQS or MSS messages IEEE 488 1 defines the method of reporting the STB and RQS but leaves the setting and clearing protocols and se mantics for the STB message undefined The standard 2 558 135240 635805458 oT EBS SRS 555 000 on 9 O uU Q O Y O Standard 7 5 3 2 1 Event Status Register 7 6 5 4 5 2 Even 5 8 8 Dd Queue Not Empty Standard Event Status Register ESE value ESE Output Queue Service ROS read by Serial Poll Request 1 Status Byte Register E Generation read by STB Les amp Logical OR Service Request Enable Register SRE value SRE Figure 4 3 IEEE 488 2 Status Reporting Model GPIB Operation 4 25 further defines specific device STB summary mes sages A Muster Summary Status MSS message is also provided which is output as bit 6 with the STB response to a STB common query The Status Byte Register is altered only when the state of the overl
181. n level the in strument proceeds with displaying the previously selected GPIB primary address The GPIB address is set by front panel programming and is stored in the non volatile memory For example with the gen erator programmed to address 18 the display shows GP18 7 Following these display messages the instru ment commences its normal operating mode and generates waveforms Note that the instrument is equipped with a non volatile memory This memory automatically monitors front panel traffic and retains its latest set up for events such as accidental power loss In case of power loss the instrument resumes operation with its previously programmed front panel set up NOTE One who does not wish to observe the power up procedure every time that the generator is turned on can easily remove the sequence of dis played messages Depressing 2nd and then Operating Mode in se quence writes a special code to the non volatile memory The next time the generator will be powered up the instrument will skip the power up pro cedure and will immediately com mence with displaying the front panel set up repeating the sequence of 2nd and Operating Mode 1 restores normal power up procedure Note that there are no front panel markings that indicate power up sequence re moval Therefore unless the instru ment is being used by one person only and to remove confusion it is recommended that power up se quence remains u
182. n the previous paragraph 2 Depress the FUNCTION push button until the light behind PHASE illuminates 3 Use the MODIFIER push buttons to modify the present setting of the phase offset Observe that the oscilloscope and note that a phase offset is generated 4 Depress the P SET to restore phase offset to factory default phase offset value 0 3 13A 4 2 Using Model 8551 as a Counter Timer Model 8551 employs a built in counter timer circuit which is used in different parts of the instrument for various purposes This internal counter timer is utilized when the instrument is placed in its PLL operating mode for automatic detection of the frequency of the external reference The counter timer reading is made available to the user and can measure external frequencies from 10Hz to over 60MHz and external periods from 1s to 16ns Frequency and period readings are given with fixed resolution of 4 digits Decimal point and exponent are displayed automatically To use Model 8551 as a frequency counter proceed as follows 1 Depress the POWER switch once to turn the power on 2 Depress the operating mode push buttons until the light behind PLL illuminates 3 Modify trigger level parameter TRIG LEVEL to the required threshold level 4 Remove any BNC cable from front panel connectors 5 Depress the FUNC push button in the MAIN PARAMETERS group until the light behind FREQ illuminates observe the programmed frequency
183. nchanged 3 5 SOFTWARE RESET An operator who is not yet fully familiar with front panel operation of the function generator may find himself locked into a dead end situation where nothing operates the way it should The fastest way of restoring the generator to a known state is by resetting its software This may be done by pressing the 2nd push button and then pressing the DCL push button second function to the LCL P SET push button The instrument then resets to its factory selected defaults Table 3 1 summarizes these de faults 3 5 1 Parameter Preset As discussed in paragraph 3 5 software reset restores all front panel parameters to their factory selected values It may however be required to preset one or two parameters and leave the rest intact In that case the instrument provides additional capabilities with its P SET preset function Depressing LCL P SET push button modifies the displayed pa rameter to its default value Default values are summarized in Table 3 1 NOTE Software reset has no effect on the stored front panel set ups Software reset also has no effect on the pro grammed GPIB address 3 6 DISPLAY MESSAGES Model 8550 has several display messages pertaining to its operation The generator also displays an error indication when a front panel programming error is detected These messages and error indications are discussed in the following Note that the instrument has a number o
184. nector To place the instrument in its stand by mode depress in sequence the 2nd and the ST BY push buttons The selected waveform light turns off indicating that the output signal is disconnected from the output connector 3 17 TRIGGERING THE FUNCTION GENERATOR Model 8550 8551 when set to one of its trigger modes accepts stimulation from a variety of sources The Operator has the option of selecting either an external source an internal source or a manual source Each triggering method is used in a different way and for different applications The triggering options are described in the following 3 16 Operating Instructions 3 17 1 Triggering The Function Generator With An External Stimulant Selecting one of the external triggering modes is simply a matter of depressing push buttons in the TRIGGER section until the light behind the desired mode illuminates When no light in the TRIGGER MODE section is on the function generator operates in its normal continuous mode The Model 8550 8551 triggers on the leading edge of the applied external signal The internal trigger level is programmable within the range of 10V The instrument may operate in one of the following external triggering modes Triggered Gated or in Counted burst mode Each mode is described in the following 3 17 1 1 Triggered Mode When set to operate in triggered mode each positive going transition at the TRIG REF INPUT connector generates a singl
185. new fuse into the fuse holder 3 Connect the ac line cord to the power connector at the rear of the unit and the power source AC Voltage Selection Fuse 103 5 to 126 5 115 207 0 to 253 0 230 1 amp slo blo 0 5 amp slo blo Table 2 1 Line Voltage and Fuse Selection 2 5 GROUNDING REQUIREMENTS To insure the safety of operating personnel the U S O S H A Occupational Safety and Health require ment and good engineering practice mandate that the instrument panel and enclosure be earth grounded All of Tabor instruments are provided with an Underwriters Laboratories U L and V D E listed three conductor power cable which when plugged into an appropriate power receptacle grounds the instrument The long offset pin on the male end of the power cable carries the ground wire to the long pin of the Euro connector DIN standard receptacle on the rear panel of the instrument To preserve the safety protection feature when operating the instrument from a two contact outlet use a three prong to two prong adapter and connect the green lead on the adapter to an earth ground CAUTION To avoid operator shock hazard do not exceed the power mains voltage 2 2 Preparation frequency rating which limits the leak age current between case and power mains Never expose the instrument to rain excessive moisture or con densation 2 6 INSTALLATION AND MOUNTING The instrument is fully solid state and dissipates only
186. ng the model 8550 in linear or logarithmic sweep operating mode transforms the instrument into an independent sweep generator The function generator has eight built in sweep modes of which four of them are linear sweep modes and four are logarithmic Select between linear or logarithmic sweep mode by depressing the OPERATING MODE 1 or push buttons until the light behind the desired mode illuminates The various sweep modes may operate in conjunction with the triggered modes 3 13 2 1 Selecting Sweep Direction When Model 8550 is placed in sweep mode linear or logarithmic the selected waveform at the output connector repeatedly changes its frequency in a direction set by the sweep start FREQ parameter to frequency set by the sweep stop STOP parameter The time for completing one sweep cycle is deter mined by the sweep time TIME parameter There are four different directions that the output waveform may sweep to The difference between the various Operating Instructions 3 11 modes is more significant when using the triggered sweep mode as described in the following SWEEP UP The function generator when trig gered sweeps from value set by FREQ to value set by STOP Sweep time is determined by TIME At the end of the sweep the output waveform remains at the stop frequency Following another trigger the output jumps quickly to its start frequency and the above cycle is repeated In normal mode the generator repeats i
187. nly the normal precautions and procedures applicable to the handling of sensitive electronic equipment The contents of all shipping containers should be checked for included accessories and certified against the packing slip to ascertain that the shipment is complete 2 3 PERFORMANCE CHECKS The instrument was carefully inspected for mechanical and electrical performance before shipment from the factory It should be free of physical defects and in perfect electrical order upon receipt Check the in strument for damage in transit and perform the electrical procedures outlined in Section 5 If there is indication of damage or deficiency see the warranty in this manual and notify your local Tabor field engineering representative or the factory CAUTION It is recommended that the operator be fully familiar with the specifications and all sections of this manual Failure to do so may compromise the war ranty and the accuracy which Tabor has engineered into your instrument 2 4 LINE VOLTAGE AND FUSES The Model 8550 accepts a primary input voltage from one of the following sources a 103 5 to 126 5 Vac 115 Vac NOMINAL b 207 to 253 Vac 230 Vac NOMINAL Tabor ships the Model 8550 set for the line voltage and with the proper fuse for the Section 2 destination country Figure 2 1 illustrates the location of the line voltage switch and fuse holeder SWP LINE OUT FUSE NT 1An15V 5 230 50 400Hz 100VA max
188. nsition Linear edge transition GPIB Operation 4 13 Table 4 5 Device Dependent Command Summary continued Mode Program Header Suffix and Data Description Data PROGRAM PARAMETERS FRQ Program output frequency MHZ HZ KHZ MAHZ AMP Program output amplitude MV V OFS Program output offset MV V PLL Program phase lock offset DEG Model 8551 only PER Program pulse period NS US MS 5 Model 8551 only WID Program pulse width NS US MS 5 Model 8551 only DTY Program fixed duty cycle PCT Model 8551 only LEE Program leading edge transition time NS US MS S Model 8551 only TRE Program trailing edge transition time NS US MS S RPT Program internal trig generator per NS US MS S BUR Program counted burst TLV Program trigger level V TPH Program trigger phase offset DEG Model 8550 only DCO Program dc output level MV V Model 8550 only STP Program logarithmic sweep stop MHZ HZ KHZ MAHZ Model 8550 only SWT Program sweep time NS US MS 5 Model 8550 only MRK Program logarithmic sweep marker MHZ HZ KHZ MAHZ Model 8550 only SSN Program linear sweep stop MHZ HZ KHZ MAHZ Model 8550 only MKN Program linear sweep marker MHZ HZ KHZ MAHZ REVIEW PARAMETER VFRQ Display output frequency VAMP Display output amplitude VOFS Display output offset VPLL Display phase lock offset Model 8551 only VPER Display pulse period Model 8551 only VWID Display pulse width Model 8551 only VDTY Display fixed duty
189. nual The auto calibration failure list is also available as a GPIB failure status query 3 9 SELECTING 2nd FUNCTIONS A few front panel push buttons were assigned a secondary function These functions are marked below the button in blue color and are accessible through the 2nd push button There are ten front panel buttons which were assigned a secondary function These functions are DCL STORE RECALL SWP MODE Model 8550 GPIB ADR LIN FIXED Model 8551 RCL MODE INT TRG STANDBY COMPL Model 8551 FAIL LIST The operation of these secondary functions is described later in this chapter Pressing the 2nd push button generates the following display read out 2nd The question mark appears blinking indicating that the instrument is ready for a consequent press of another push button which was assigned a sec ondary function Depressing 2nd once more cancels this function Second functions DCL SWP MODE LIN FIXED INT TRG ST BY and COMPL function are executed immediately STORE RECALL GPIB ADR RCL MODE and FAIL LIST will be executed only after depressing the EXE push button 3 10 AUTO CALIBRATION Model 8550 provides an auto calibration function that may be operated at any time either from the front panel or through a GPIB command Operating the auto calibration is very simple and can be done by anyone no special skills are required Although this function can give the user relative confidence that
190. nytime from the front panel or GPIB command The self calibration function compares the output signal parameters to built in internal references and stores correcting fac tors in special tables If calibration routine fails or can not be completed due to electrical faults the generator produces a failure list that can be evaluated either from the front panel or through GPIB status reporting command Besides its normal continuous mode Model 8550 offers a variety of interrupted and controlled modes Output waveform may be gated triggered or may generate a counted burst of output waveforms A built in trigger generator having a programmable General Information 1 1 period can replace an external trigger stimulant The MANUAL trigger is just an additional convenience for front panel operation The generator may also be placed in a number of externally controlled modes such as VCO FM AM and pulse width modulation PWM Model 8551 only Model 8550 may be used as an independent sweep generator with its output swept over an ex ceptionally wide range of 10 decades The instrument offers a choice of eight sweep modes both linear and logarithmic to cover a large number of applica tions A MARKER output provides an oscilloscope Z axis modulation to intensify segments of sweep trace Alternately Model 8550 may also be used as a stand alone phase lock generator The instrument locks automatically to an external signal and equates it
191. observe that output changes from OV to 5V when marker frequency is reached 7 Change Operating Mode setting to Logarithmic Sweep and repeat the above tests 8 Change 8550 Trigger Mode to Triggered Observe that 8550 output sweeps once for every time that the MANUAL push button is depressed 9 Change 8550 Trigger Mode to Gated Observe that 8550 output sweeps continuously as long as the MANUAL push button is depressed 10 Change 8550 Trigger Mode to Burst Observe that 8550 output sweeps twice for every time that the MANUAL push button is depressed Change burst setting and observe that the number of sweeps corresponds to the number of selected burst count 5 9 16 Pulse Width Accuracy model 8551 Accuracy Specifications 5 2ns from 10 ns to 99 9 ns 4 2ns from 100 ns to 999 ms Equipment Counter Oscilloscope 1 Set 8551 as follows CONTROL POSITION Operating Mode Pulse Output Squarewave 2 Set counter to pulse width measurement and counter input impedance to 500 Connect 8550 output to counter input 3 Set 8551 Pulse Width and Period and verify counter reading as follows PERIOD WIDTH COUNTER SETTING SETTING READING 277 7 ns 50 0 ns 46 0 ns 54 0 ns 277 7 ns 99 9 ns 93 0 ns 107 ns 277 7 ns 100 ns 94 0 ns 106 ns 1 500 us 500 ns 478 ns 522 ns 15 00 us 5 00 us 4 8550 us 150 0 us 50 0 us 48 0 us 52 0 us 1 500 ms 500 us 480 us 520 us 15 00 ms 5 00 ms 4 8550 ms 150 0 ms 50 0 ms 48
192. omposed of a sequence of functional syntactic elements Legal IEEE 488 2 program commands are created from functional elements sequences Some commands of universal instrument system application have been defined by the IEEE 488 2 They are the common commands these commands and queries are specific path selections through the functional syntax diagram as specified in the IEEE 488 2 standard The remaining commands are de vice specific and are generated by the device designer using the functional syntax diagram and the needs of the device The functional elements include sepa rators terminators headers and data types These elements are discussed in the following 4 9 1 Functional Element Summary GPIB Operation 4 9 Program Message Represents a sequence of zero or more Program Message Unit elements separated by Program Message Unit Terminator elements Program Message Unit Represents a single command or programming data received by the device Command Message Unit Represents a single command or programming data received by the device Query Message Unit Represents a single query sent from the controller to the device Program Data Represents any of the six dif ferent program data types Program Message Unit separator Separates the Program Message Unit elements from one another in a Program Message Program Data gt Separates sequential Program data elements
193. on 3 of this manual To send GET command over the bus the controller must perform the following sequence 1 Set ATN true 2 Address the Model 8550 to listen 3 Place the GET command on the data bus GET can also be sent without addressing by omitting step 2 4 8 4 Unaddress Commands The two unaddress commands are used by the controller to simultaneously remove all talkers and listeners from the bus ATN is low when these multiline commands are asserted UNL Unlisten All listeners are removed from the bus at once when the UNL commands is placed on the bus UNT Untalk The controller sends the UNT command to clear the bus of any talkers 4 8 5 Device dependent Commands The meaning of the device dependent commands is determined by instrument configuration Generally these commands are sent as one or more ASCII characters that tell the device to perform a specific function For example M2 is sent to the Model 8550 to place the instrument in the external trigger mode The IEEE 488 2 bus treats device dependent com mands as data in providing that ATN is high false when the commands are transmitted 4 8 6 Common Commands and Queries Since most instruments and devices in an ATE System use similar commands which perform identical functions the IEEE 488 2 document has specified a common set of commands and queries which all device must use This avoids the problem in which devices from various manufacturers used a
194. onformity For products warranties requiring return to Tabor products must be returned to a service facility designated by Tabor Buyer shall prepay shipping charges taxes duties and insurance for products returned to Tabor for warranty service Except for products returned to Buyer from another country Tabor shall pay for return of product to Buyer Tabor shall have no responsibility hereunder for any defect or damage caused by improper storage improper installation unauthorized modification misuse neglect inadequate maintenance accident or for any product which has been repaired or altered by anyone other than Tabor or its authorized representative and not in accordance with instructions furnished by Tabor Exclusion of Other Warranties The Warranty described above is Buyer s sole and exclusive remedy and no other warranty whether written or oral is expressed or implied Tabor specifically disclaims the implied warranties of merchantability and fitness for a particular purpose No statement representation agreement or understanding oral or written made by an agent distributor representative or employee of Tabor which is not contained in the foregoing Warranty will be binding upon Tabor unless made in writing and executed by an authorized Tabor employee Under no circumstances shall Tabor be liable for any direct indirect special incidental or consequential damages expenses losses or delays including loss of profits base
195. only a selected instrument instead of all devices simul taneously Model 8550 will return to the default conditions listed Tables 3 1 and 4 4 when re sponding to an SDC command To transmit the SDC command the controller must perform the following steps 1 Set ATN true 2 Address the Model 8550 to listen 3 Place the SDC command on the data bus GTL Go To Local The GTL command is used to remove the instrument from the remote mode of operation Also front panel control operation will usually be restored if the LLO command was pre viously sent To send the GTL command the controller must perform the following sequence 1 Set ATN true 2 Address the Model 8550 to listen 3 Place the GTL command on the bus NOTE 4 8 GPIB Operation The GTL command does not remove the local lockout state With the local lockout condition previously set the GTL command will enable front panel control operation until the next time a listener address command is re ceived This places the Model 8550 in the local lockout state again GET Group Execute Trigger The GET command is used to trigger or arm devices to perform a specific task depends on device configuration Al though GET is considered to be an addressed command many devices respond to GET without being addressed Using the GET command is only one of several methods that can be used to initiate a trigger More detailed information on triggering can be found in Secti
196. or Part Number Vendor Code 0104 10020 0104 12520 0104 20020 0104 40220 0104 47520 0104 49920 0104 10030 0104 33230 0111 1103B 0110 01030 0110 01820 0111 1272B 0114 01400 0500 60200 0500 56500 0500 53210 0500 56750 0560 00850 0500 90900 0500 56330 0540 01100 0560 00700 0500 56310 0500 91000 0500 60950 0500 53700 0500 57200 0500 45300 0500 56360 0500 45000 0500 40900 0500 40950 0500 40930 6100 6191 1532 01070 1500 01040 1200 11000 Table 8 2 Model 8551 Parts List continued Reference Description and Tabor Designation Commercial Part Number Part Number Vendor Code DS5 7 SEG LED HDSP 7801 1200 11100 50434 DS6 t1 LED HDSP 7807 1200 11200 50434 0 7 0 15 0 25 0 29 0 32 0 35 MINI 3MM LED RED HLMP1301 1000 00300 50434 0 8 14 0 16 24 0 26 0 28 0 30 31 0 33 34 0 36 41 LED MV 54124 A 1000 00900 14936 FLAT CABLE 20 PIN 9L28020 6800 50600 10903 TSTR PNP 2N4403 0400 01800 04713 RES COMP 220 5 1 4W 0100 02210 74902 RES COMP 10 5 1 4W 0100 01000 74902 KEY SWITCH M320 03 E1 1 2000 61600 0128551 741542 0510 05300 04713 7415138 0510 02700 04713 Main Board Assembly 6100 6185 C1 C2 CAP ELEC 100 25V 2222 036 1533 01070 C3 C4 CAP ELEC 3300u 35V 2222 037 1534 03380 C5 C6 CAP ELEC 1000 50V 2222 037 1535 01080 C7 C8 CAP ELEC 10 000u 16V 2222 037 1532 01090 C9 CAP ELEC 1000u 25V 2222 037 1533 01080 C10 C11 CAP ELEC 100 16V 2222 036 1532 01070 CAP TANT 10u 25V T351B106M025A81
197. play messages which are associated with errors involving GPIB interface programming These messages are discussed in detail in Section 4 of this manual There is one message however which should be explained at this point because it may interfere with front panel operation A remote enable or a device dependent command sent to the instrument through the bus turns the REMOTE light on In this case all front panel push buttons except LCL are disabled Press one of these push buttons causes the function generator to respond with the following message LcL This message indicates that the instrument expects that the LCL push button be first depressed other wise front panel operation is ignored After the LCL button is depressed the REMOTE light turns off and the instrument is ready to accept further front panel programming sequences 3 8 5 Auto Calibration Errors Model 8550 provides an auto calibration function which may be used by the operator In the event that the calibration routine fails to successfully com plete the generator generates a calibration failure list and starts displaying the following message FAIL d Where d represents blinking digits in the range of 1 to 9 A function LED indicator in the MAIN PARAMETERS blinks simultaneously indicating the area where the generator failed to calibrate Operating the auto calibration function and interpreting the gen erated failure list are described later in this ma
198. put Voltage Min Pulsewidth Operation Locking Range Phase Offset Range Resolution Accuracy PWM CHARACTERISTICS Sensitivity Band Width Pulse Modes Pulse Period Range Resolution Accuracy and Jitter Pulse Width Range Setting Accuracy Duty Cycle Range Resolution Ramp Modes Ramp Period Range Resolution Ramp Width Range Setting Accuracy Resolution Duty Cycle Range 196 for modulation depth 9096 carrier frequency 1 00MHz and modulation frequency 50KHz lt 3 for modulation depth lt 50 carrier frequency lt 50 00MHz and modulation frequency lt 50KHz PHASE LOCK CHARACTERISTICS Via TRIG REF BNC terminal 10KQ 5 500mVp p 20V dc peak ac 10ns Output locks automatically to the frequency and phase of an external signal 10Hz to over 60MHz Continuously adjustable from 180 to 180 10Hz to 19 99MHz 1 3 3 of reading 10Hz to 100KHz 0 to 5V 20 produces gt 10 pulse width change from pulse width setting DC to 70KHz PULSE RAMP CHARACTERISTICS Model 8551 only Symmetrical Pulse Positive Pulse Negative Pulse and Complement 20 00ns to 99 99s 4 digits Same as for frequency 10 0ns to 999ms 5 2 5 10 0ns to 99 915 4 2ns 100ns to 999ms 1 to 855096 up to 99 using complement mode 3 digits Positive or Negative going ramps 7 000us to 99 99s 4 digits 5 00us to 999ms 396 5 00us to 999ms 3 digits
199. put amplifier circuit is capable of driving its output waveforms into a 500 load The analog signals are controlled by D to A converters The D to A converters receive their controlling information through serial to parallel con verters directed by the microprocessor components Model 8550 8551 is mechanically constructed on a number of plug in boards Each board contains different electronic circuits making it easy for trou bleshooting and servicing Model 8550 8551 has four plug in boards CPU board VCO board Calibration board Output Amplifier board and Main board Model 8551 has one additional pulse width and rise fall time control board The power supplies to the various sections of the generator is built on the main board assembly together with the connections for the plug in boards The various circuits on each board are described in the following 6 3 C P U BOARD Model 8550 8551 operation is supervised by an internal microprocessor CPU The CPU controls parameter selection process front panel switching the displayed read out and IEEE operation All of these tasks are performed under software supervision This section briefly describes the operation of the various sections of the microprocessor and its as sociated digital circuitry For more complete circuit details refer to the schematics at the end of this manual Circuit operation centers around the microproces sor unit CPU U5 The CPU is an 8 bit microproc
200. put and Modifiers 3 2 1 1 Operating Mode Two push buttons in the operating mode group provide selection between four operating modes Selection of one of the operating modes is done by depressing one of these buttons The selected mode is indicated by an LED 3 2 1 2 State Three push buttons are included in the status group The function of each of these buttons is described in the following POWER The POWER switch controls the AC power to the instrument Pressing and releasing the switch once turns the power on Pressing and releasing the switch a second time turns the power off 2nd EXE Several push buttons were assigned a second function which are only accessible after the 2nd button was depressed These functions are marked below the buttons in blue script Some second functions require that the EXE push button be pressed again before the function is executed LCL P SET DCL The LCL P SET push button when depressed and the instrument is in its remote mode but not in remote lockout condition LLO restores the instrument to its local operating mode When the generator is in its local operating mode depressing this push button restores only the currently displayed parameter to its factory pre set value other parameters are not affected by pressing this button Front panel P SET values are listed in Table 3 1 A third function is also assigned to this switch Depressing this push button after the 2nd button cons
201. r as a fixed duty cycle pulse generator and as a phase locking generator Similar to Model 8550 selecting an operating modes is done by depressing one of the OPERATING MODE or 1 push buttons until the light behind the desired mode illuminates Description of the various modes which can be used on Model 8551 is given in the following 3 13A 1 Normal Function Generator Operating Mode Model 8551 Function generator operating mode is the normal operating conditions where the output waveform is symmetrical about its horizontal and vertical axis The normal operating mode also permits a vertical offset of its output waveform The generator is placed in its normal operating mode when the light behind FUNC illuminates Triggered operation and externally controlled modes such as VCO and AM may operate in conjunction with the normal function generator operating mode 3 13A 2 Pulse Generator With Variable Pulse Width Operating Mode Model 8551 Model 8551 offers additional capability to the basic normal function generator by allowing modification of parameters which are associated with the pulse output When the pulse generator operating mode is selected one can modify the pulse width the pulse period and independently adjust the rise and the fall times Variable ramp width function is also made available The generator is placed in its pulse generator operating mode when the light behind PULSE illu minates Triggered operat
202. rams given in Section 9 The theory of operation section in this manual may also assist in understanding how the circuits should operate 7 5 1 Frequency Calibration Failures Failures in the frequency generation circuits are indicated by a blinking FREQ indicator with an associated displayed readout In general frequency failures may generate as a result of faults in the V C O current generator and the counter circuits The following is a list of possible frequency calibration failures Possible solutions to remove the source of these errors are suggested FAIL 1 Check the capacitor multiplier circuit Check K2 and their driving circuit on the V C O board Check capacitor multiplier circuit Check K2 K3 and their driving circuit on the V C O board Check C21 Q8 K2 K3 and their driv ing circuit on the V C O board Check C22 Q9 K2 K3 and their driv ing circuit on the V C O board Check C23 Q10 K2 and their driv ing circuit on the V C O board Check C24 Q11 K2 K3 and their driv ing circuit on the V C O board Check C36 on the V C O board Check U16 U25 and their associated compo nents on the calibration board Check C36 and its drive on the V C O board Check U40 U16 U25 and their associated components on the calibration board Check U9 and its associated compo nents on the calibration board FAIL N 1 FAIL 1 FAIL 4 FAIL 5 FAIL 6 FAIL 7 FAI
203. ration 4 8 BUS COMMANDS While the hardware aspect of the bus is essential the interface would be essentially worthless without appropriate commands to control the communications between the various instruments on the bus This paragraph briefly describes the purpose of the bus commands which are grouped into the following three categories Table 4 3 IEEE 488 Bus Command Summary 1 Uniline commands Sent by setting the asso ciated bus line low true 2 Multiline commands General bus commands which are sent over the data lines with the ATN line low true 3 Device dependent commands Special com mands that depend on device configuration sent over the data lines with ATN high false 4 Common commands and queries A special set of commands that all devices must use and does not depend on device configuration sent over the data lines in the same format as the device dependent commands 4 8 1 Uniline Commands Uniline commands are sent by setting the associated bus line to low The ATN IFC and REN commands are asserted only by the system controller The SRQ command is sent by an external device The EOI command may be sent by either the controller or an external device depending on the direction of data transfer The following is descriptions of each command REN Remote Enable The remote enable command is sent to the Model 8550 by the controller to set the instrument up for remote operation Gen CO
204. rawings which are located at the end of this instructions manual 6 2 OVERALL FUNCTIONAL DESCRIPTION The Model 8550 8551 is fully programmable function generator having various standard output functions All parameters are adjustable through front panel touch switches or through IEEE programming The high performance of the Model 8550 8551 is accom plished by utilizing a very fast discrete analog circuits Microprocessor and digital circuits control the per formance of the analog circuits and permit direct interfacing to the front panel keyboard and display and to the GPIB Figure 6 1 is a block diagram of the most important sections of the Model 8550 8551 Refer to this block diagram throughout the following general description The heart of the function generator is its VCO where two identical currents with opposite polarities are created These two currents are switched in on and off charging and consequently discharging a capacitor This cycle generates a continuous ascend ing and descending voltage ramps The repetition rate depends on the applied capacitor and the sup plied current The output of the VCO also generates a rectangular waveform The same ramp is used for driving the triangle and buffer The triangle waveform is also utilized in generating the sinewave output by using a sine shaper The three basic waveforms are then amplified or attenuated through the output amplifier and fed to the output connector The out
205. rent source 6 6 2 Waveform Selector Circuit Model 8550 8551 is capable of generating different waveforms at the output connector such as sine and triangular waveforms The waveform selector circuit selects the necessary waveform to be applied to the output amplifier circuit This circuit is comprised of a quad DMOS switch U1 Its output is controlled by comparators U3a U3c and U3d The output of the waveform selector circuit is connected to the amplitude modulator circuit 6 6 3 Amplitude Modulation Circuit The amplitude modulation circuit serves two purposes The first task is control the amplitude at the output connector the second is to modulate the carrier signal which is generated by the Model 8550 8551 with an external modulating signal The amplitude modulator is made of an analog multiplier circuit U2 differential amplifier U9 and their associated components One input of U2 receives the waveform from the waveform selector circuit the second input receives either a dc level for amplitude control or an external signal for amplitude modulation The amplitude level is controlled by a digital to analog converter U10 operational amplifier U7 and their associated components 6 6 4 Step Attenuator Circuit The signal from the amplitude modulator is attenuated with the step attenuator circuit before it is routed to the output amplifier section and then with a post attenuator before the signal is applied to the ou
206. riginal containers until ready for installation 2 Remove the devices from the protective con tainers only at a properly grounded work station Also ground yourself with a suitable wrist strap 3 Remove the devices only by the body do not touch the pins 4 Any printed circuit board into which the device is to be inserted must also be grounded to the bench or table 5 Use only anti static type solder sucker 6 Use only grounded soldering irons 7 Once the device is installed on the PC board the device is normally adequately protected and normal handling resume 5 6 CLEANING Model 8550 should be cleaned as often as operating condition require Thoroughly clean the inside and the outside of the instrument Remove dust from inaccessible areas with low pressure compressed air or vacuum cleaner Use alcohol applied with a cleaning brush to remove accumulation of dirt or grease from connector contacts and component ter minals 5 2 Maintenance And Performance Tests Page Clean the exterior of the instrument and the front panel with a mild detergent mixed with water applying the solution with a soft lint free cloth 5 7 REPAIR AND REPLACEMENT Repair and replacement of electrical and mechanical parts must be accomplished with great care and caution Printed circuit boards can become warped cracked or burnt from excessive heat or mechanical stress The following repair techniques are suggested to avoid inadvertent destruc
207. s ice e Mee dele eG ume e eu uiis 3 8 8 3 Pulse Ramp Set up Errors Model 8551 Only 3 8 8 4 1 488 2 Errors o ee Bo Xon 3 8 Contents i 3 8 5 Auto calibration Errors sss asena a ac bob RS 3 9 Selecting 2nd Functions 3 10 Auto Calibration 3 11 Reviewing The Auto Calibration Failure 51 3 12 Modifying Parameters 3 12 1 Using The Modifier 3 12 2 Modifying The Range 3 12 3 Parameter Limits 3 13 Selecting an Operating Mode Model 8550 3 13 1 Normal Function Generator Operating Mode Model 8550 3 13 2 Linear Logarithmic Sweep Operating Mode Model 8550 3 13 2 1 Selecting Sweep Direction 3 13 3 Phase Locking Generator Operating Mode Model 8550 3 13 3 1 Generating Phase Offsets 3 13 3 2 Using Model 8550 As a Frequency Counter 3 13A Selecting an Operating Mode Model 8551 3 13A 1 Normal Function Generator Operating Mode Model 8551 3 13A 2 Pulse Generator With Variable Pulse Width Operating Mode Model 8551 3 13A 3 Pulse Generator With Fixed Duty Cycle Oper
208. s Formats Proto cols and Common Commands The original docu ment IEEE 488 1978 was re titled IEEE 488 1 The IEEE 488 2 standard was designed to make the interface system easier to use by requiring that all devices provide certain capabilities such as talk and listen respond to device clear commands and be capable of service requests Other functions such as parallel poll are left optional with the instrument manufacturer The Model 8550 complies with all of the mandatory IEEE 488 1 and IEEE 488 2 require ments Some of the issues which IEEE 488 2 Ad dresses are 1 A required minimum set of IEEE 488 1 capa bilities 2 Reliable transfer of messages between a talker and listener and precise syntax in those messages 3 A set of commands which would be useful in all instruments 4 Common serial poll status reporting 5 Synchronization programming with instrument functions This section contains general bus information as well as detailed programming information and is divided as follows 1 General introductory information pertaining to the IEEE 488 bus may be found primarily in para graphs 4 2 through 4 5 2 Information necessary to connect the Model 8550 to the bus and to change the bus address is contained in paragraphs 4 6 and 4 7 3 Programming of the instrument with general bus command is covered in paragraph 4 8 4 Device dependent command programming is described in detail in paragraph 4 10 The command
209. s outlined in this section can be considered to be the most important since they control virtually all instru ment functions 5 Additional information pertaining to device status reporting and error messages can be found in para graphs 4 13 and 4 15 4 2 BUS DESCRIPTION The IEEE 488 bus was designed as a parallel data transfer medium to optimize data transfer without using as excessive number of bus lines In keeping with this goal the bus has only eight data lines which are used for both data and most commands Five bus management lines and three handshake lines round out the complement of signal lines Since the bus is of parallel design all devices connected to the bus have the same information available simultaneously Exactly what is done with the infor mation by each device depends on many factors including device capabilities A typical bus configuration for remote controlled operation is shown in Figure 4 1 The typical system will have one controller and one or more instruments to which commands are given and from which data is received There are three categories that describe device operation These include controller talker listener The controller controls other devices on the bus A talker sends data while a listener receives data an instrument may be a talker only a listener only or both a talker and listener GPIB Operation 4 1 Figure 4 1 IEEE Bus Configuration
210. s 3 trough 5 may be repeated for other instruments on the bus by using the correct talk address for each instrument ATN must be true when the talk address is transmitted and false when the status byte is read SPD Serial Poll Disable The SPD command is sent by the controller to remove all instrumentation on the bus from the serial poll mode GPIB Operation 4 7 Table 4 4 Default Conditions Status After SDC DCL or RST AD ModeDefaultStatus Operating Mode Model 8550 FO Sweep Direction 51 Trigger Modes M1 Control Modes CTO Output Waveforms W1 Output Disable Enable Mode DO Pulse Ramp Output Mode CO Edge Control LO Response Message Format Response Message Terminator 20 Event Status Enable Mask 5 0 SRQ Enable Register Mask SREO Normal Start to stop Normal continuous mode Off Sinewave output Output enabled Complement OFF Model 8551 Fastest edge transition Model 8551 Response header OFF New line LF END EOI terminator No mask No mask 4 8 3 Addressed Commands Addressed commands are multiline commands that must be preceded by a listen command derived from the device s primary address before the instrument will respond Only the addressed device will respond to each of these commands SDC Selective Device Clear The SDC command performs essentially the same function as the DCL command except that only the addressed device will respond This command is useful for clearing
211. s a frequency reading of 1 020 MHz Verify that DMM reading is 1 V 100 mV 5 Change power supply leads polarity and vary power supply output voltage until the counter displays a frequency reading of 980 0 KHz Verify that DMM reading is 1 V 100 mV 6 Change 8550 MOD Mode setting to VCO 7 Vary power supply output voltage until the counter displays a frequency reading of approximately 1 KHz Verify that DMM reading is 4 7 V 500 mV 5 9 15 Sweep Characteristics model 8550 Specifications Logarithmic 10 decades Linear 3 decades Automatic up down up down and down up directions Gated Triggered and counted sweep Equipment Oscilloscope 1 Set 8550 as follows CONTROL POSITION Operating Mode Linear Sweep Sweep Direction Down Start Frequency 9 999 MHz Stop Frequency 1 000 MHz Marker frequency 5 000 MHz 2 Connect 8550 output connector to oscilloscope input Set oscilloscope so that sweep may be ob served Note that 8550 sweeps down 3 Modify 8550 sweep Time setting and observe that sweep time changes accordingly Reset sweep time to 1 second 4 Change sweep direction setting to UP and observe that 8550 sweeps up Change sweep direction to up down and watch the result 5 Connect the rear panel Sweep Out BNC connector to oscilloscope and observe that DC level changes from 0 to 5V in approximately one second for a full sweep cycle 6 Connect the rear panel Marker Out connector to the oscilloscope and
212. s are less than 6 ns Verify that overshoot and undershoot are less than 5 of amplitude 5 9 6 Sine Characteristics Specified total harmonic distortion 196 from 10 00mHz to 100 KHz Specified harmonic signals gt 40 dB below the carrier level from 100 KHz to 2 000 MHz 21 dB below the carrier level from 2 000 MHz to 50 MHz Equipment Distortion Analyzer Spectrum Analyzer 50Q feedthrough termination 20dB attenuator 1 Connect 8550 output to distortion analyzer input 2 Set distortion analyzer to distortion measure ments set 8550 frequency setting and verify distortion reading as follows 8550 SETTING DISTORTION READING 10 00 Hz lt 1 100 0 Hz lt 1 1 000 KHz lt 1 10 00 KHz lt 1 100 0 KHz lt 1 1 000 MHz lt 1 3 Tune spectrum analyzer for minimum display amplitude and adjust gain so that fundamental cor responds to 0 dB 4 Change 8550 amplitude setting to 10 0 V 5 Connect 8550 output to spectrum analyzer input through a 20dB feedthrough attenuator 6 Set 8550 frequency setting and verify harmonic distortions levels as follows 8550 SETTING HARMONICS LEVEL 2 000 MHz gt 40 dB 50 00 MHz gt 21 dB 5 9 7 Sine Flatness Level Flatness 2 to 9 999 MHz 15 to 50 00 MHz Equipment Oscilloscope 1 Set 8550 as follows CONTROL POSITION Amplitude 1 20 V 2 Connect 8550 OUTPUT to the oscilloscope set oscilloscope input impedance to 500 and set oscil loscope to display the sine
213. s described in Figure 5 3 5 9 13 Amplitude Modulation Characteristics 3 Set external function generator frequency setting Specifications Envelop Distortion 196 with carrier to 10 0 KHz amplitude setting to 2 5 V and offset frequency 1 000 MHz 396 with carrier frequency setting to 1 25 V to 50 00 MHz 4 Verify that reading on the distortion analyzer is Equipment Pulse function generator distortion ana less than 1 lyzer AM detector DISTORTION ANALYZER o 8020 8550 C 2 2K OU OUT DETECTOR 50 D152 2hr Figure 5 3 Amplitude Modulation Operation Check 5 8 Maintenance And Performance Tests Page 5 Verify that reading on the distortion analyzer is less than 396 from 10 00 MHz to 50 00 MHz 5 9 14 FM and VCO Characteristics Specifications VCO 0 to 4 7 V 20 produces 1 1000 change from main frequency Equipment Counter DMM dc power supply 1 Set 8550 as follows CONTROL POSITION MOD Mode FM Frequency 999 9 KHz 2 Connect 8550 output to counter input and note frequency reading on the counter 3 Connect dc power supply output to 8550 MOD input Connect DMM leads to power supply output 4 Vary power supply output voltage until the counter display
214. s displayed The selected parameter is indicated by an LED Each row of LEDs is associated with a specific operating mode The parameters in the fol lowing may be displayed and modified Table 3 2 lists the limits for each of the above parameters 1 FUNCTION FREQ Frequency of the selected output wave form Frequency is defined for repetitive signals only When the function generator is set to operate in triggered mode the programmed frequency value has no effect on the output In gated mode the frequency defines the repetition rate within the gating signal In sweep mode the programmed value defines the sweep start point The programmed frequency retains its value at both SYNC and the main output connectors The frequency parameter may be pro grammed within the range of 10 00mHz to 50 00MHz Preset value is set to 1 000KHz AMPL Amplitude of the selected waveform at the main output connector The output signal is driven from a 500 source therefore the value of the amplitude parameter is specified and accurately controlled only when the output is terminated with 500 If the signal from the output connector is connected to an high impedance circuit the actual amplitude level at the output connector is doubled Amplitude control has no effect on the amplitude level at the SYNC output connector The amplitude parameter may be programmed within the range of 10 0mV to 16 0V Preset value is set to 1 00V OFST DC offset of the sel
215. s of the modulating signal should be observed to avoid damage to the input circuit 3 14 3 Voltage Controlled Oscillator VCO Mode Placing the function generator in VCO voltage con trolled oscillator operating mode removes the fre quency control from its output connector The fre quency of the selected waveform is then proportional to an amplitude level of a signal which may be applied to the VCO IN connector The instrument is placed in its VCO mode when the light behind VCO illuminates To operate the generator as a voltage controlled amplifier first select the VCO mode then apply the control voltage to the front panel INPUT connector Input limits should be observed to avoid damage to the input circuit Note that although the FM mode is not available on the Model 8551 if required the VCO input may be used to frequency modulate the generator 3 14 4 Pulse Width Modulation PWM Mode model 8551 only Placing the Model 8551 in PWM pulse width modu lation operating mode removes the pulse width control from its output connector The pulse width at the output connector is then proportional to an amplitude level of a signal which is applied to the front panel control input The instrument is placed in its PWM mode when the light behind PWM illuminates To pulse width modulate the generator first select the PWM mode then apply the control signal to the front panel INPUT connector Input limits should be observed to avoid
216. s output frequency and phase to that provided by the external reference The operator may then gen erate a phase offset between the reference signal and the generators output Phase offset is adjusted within a range of 180 Model 8550 provides an output level from 20mV to 32Vp p into open circuit or 10mV to 16Vp p into 500 DC offset plus amplitude are independently variable within two window levels 16V and 1 6V into open circuit This special characteristics warrants production of extremely small signals at an elevated DC environment Model 8551 is a pulse function generator and is also described in this manual This instrument is identical in its basic functions to the Model 8550 In addition this instrument offers Pulse and Ramp waveforms Pulse width and ramp width are adjustable within a range of 10 0ns to 999ms Model 8551 provides control over the transition times for the leading and trailing edges each can be adjusted independently within a common range Pulse complement and inverted ramp functions are also available This manual identifies those features and specifications that only apply to Model 8551 1 3 INSTRUMENT amp MANUAL IDENTIFICATION The serial number of the instrument is located on the rear panel of the instrument The two most significant digits identify instrument modifications If this prefix differs from that listed on the title page 1 2 General Information of this manual there are differences
217. se Header and Common Response Header A Simple sponse Header is defined as Response gt For example FRQ Leading White Space ele ments are not permitted Upper lower case alpha characters are treated with the same semantic equiva lence Compound Response Header is not used in model 8550 and will not be discussed here A Common Response Header is defined as Response Mnemonic gt For example SRE Leading White Space ele ments are not permitted Upper lower case alpha characters are treated with the same semantic equiva lence 4 11 5 Response Data A Response Data functional element is used to convey a variety of response information related to the Response Header The element type is de termined by the eliciting query Non Decimal Re sponse Data String Response Data and Arbi trary Block Response Data functional elements are not implemented in Model 8550 Therefore it shall not be discussed in this manual 4 11 5 1 Character Response Data The Character Response Data functional element is used to convey information best expressed GPIB Operation 4 21 mnemonically as a short alpha or alphanumeric string It is useful when numeric parameters are inappro priate for example model number and manufacturer identification 4 11 5 2 Decimal Numeric Response Data The Decimal Numeric Response Data is a flexible version of the three numer
218. se width reading on the counter 3 Connect dc power supply output to the 8551 MOD input Connect DMM leads in parallel to power supply output 4 Vary power supply output voltage until the counter displays a pulse width reading variance of 10 Verify that DMM reading is between 4 V to 6 PERIOD WIDTH LEAD TRAIL SETTING SETTING SETTING 1 000 us 500 ns 99 ns 2 000 us 1 00 us 500 ns 20 00 us 10 0 us 5 00 us 200 0 us 100 us 50 0 us 2 000 ms 1 00 ms 500 us 20 00 ms 10 0 ms 5 00 ms 200 0 ms 100 ms 50 0 ms COUNTER READING 93 0 ns 107 0 ns 478 ns 522 ns 4 8550 us 5 20 us 48 0 us 52 0 us 480 us 520 us 4 8550 ms 5 20 ms 48 0 ms 52 0 ms Table 5 3 Rise Fall Time Accuracy Tests 4 Disconnect 8551 output from the counter and connect to oscilloscope input Set oscilloscope input impedance to 50Q 5 10 Maintenance And Performance Tests Page Theory of Operation Section 6 6 1 INTRODUCTION This section contains an overall functional description of the 8550 series function generators as well as detailed circuit analysis of the various sections of the instruments Information pertaining to the pulse width the amplitude modulation and the standard IEEE interface are also included Information is arranged to provide a description of individual functional circuit blocks As an aid to understanding the descriptions are keyed to a block diagram and to Detailed schematics and component layout d
219. set ting 5 Connect a BNC cable from the reference source to the front panel REF INPUT connector 6 Observe that the displayed reading is modified to read the frequency of the external signal and that the decimal point blinks at a constant rate indicating that the generator is its timer mode of operation 7 Remove the BNC cable from the REF input connector and observe that the decimal point stopped blinking and that the display resumes its normal programmed frequency parameter To use Model 8551 as a timer proceed as follows 1 Depress the POWER switch once to turn the power on 2 Depress the operating mode push buttons until the light behind PLL illuminates 3 Modify trigger level parameter TRIG LEVEL to the required thrash hold level 4 Remove any BNC cable from front panel connectors 5 Depress the PULSE push button in the MAIN PARAMETERS group until the light behind PER illuminates observe the programmed period setting 6 Connect a BNC cable from the reference source to the front panel REF INPUT connector 7 Observe that the displayed reading is modified to read the period of the external signal and that the decimal point blinks at a constant rate indicating that the generator is its timer mode of operation 8 Remove the BNC cable from the REF input connector and observe that the decimal point stopped blinking and that the display resumes its normal programmed period parameter 3 14 SELECTING A MODULA
220. set ups Front panel set ups can be recalled one at a time The generator also employs a special recall mode that permits automatic scrolling through the stored set ups for sequential tests The operator may select to scroll in an ascending or descending order De scription how to save and recall set ups and how to use the recall mode is given in the following 3 19 1 Storing Set ups First modify front panel parameters as necessary to perform the required test Parameter modification procedure is discussed in paragraph 3 12 When all parameters are programmed and verified for accuracy proceed with storing this set up as follows 1 Depress the 2nd and STORE push button in sequence and observe that the display is modified to indicate the following S xx 2 appears blinking S means that the instrument is placed in memory store mode indicates the number of the present storage cel Numbers may range from 00 to 30 Depressing any other push button removes the gen erator from the memory store mode and leaves front panel settings unchanged 2 To program individual memory cells for a specific front panel set up depress the MODIFIER x1 fl or x1 U until the desired memory number is displayed Depressing EXE locks in the entire front panel set up for later usage The instrument then resumes normal operation 3 Repeat the above procedure for as many set ups that are required Stored front panel set ups are
221. sformer may be installed for 100 Vac and 200 Vac ranges The instrument was shipped from the factory set for an operating voltage of 230 Vac To change the line voltage proceed as follows WARNING Disconnect the Model 8550 from the power cord and all other sources before changing the line voltage set ting 1 Using a flat blade screwdriver place the line voltage selection switch in the desired position The selected voltage is marked on the selection switch 2 Install a power line fuse consistent with the operating voltage See paragraph 5 3 CAUTION The correct fuse type must be used to maintain proper instrument protec tion 5 3 FUSE REPLACEMENT The Model 8550 has a line fuse to protect the instrument from excessive current This fuse may be replaced by using the procedure described in the following WARNING Disconnect the instrument from the power line and from other equipment before replacing the fuse 1 Place the end of a flat blade screwdriver into the slot in the LINE FUSE holder on the rear panel Push in and rotate the fuse carrier the holder and its internal spring will push the fuse and the carrier out of the holder 2 Remove the fuse and replace it with the proper type using Table 5 1 as a guide CAUTION Do not use a fuse with a rating higher than specified or instrument damage may occur If the instrument persistently blows fuses a problem may exist within the instrument If so the problem
222. stant control of the various circuits The timing capacitors for the pulse width ranges are switched in and out by switching transistors Q29 through Q34 The timing capacitors for the transition times ranges are switched in and out by switching transistors Q3 and Q5 through Q7 These switching transistors are driven by quad operational amplifiers U3 U15 and U17 The gate selector made of U16c and U16d is responsible for selecting a waveform for the output amplifier section Selection can be made from rec tangular squarewave or variable pulse width square wave The gate selector U16a and U16b is responsible for routing the correct signal to the counter circuit Selection for the counter is made between the variable pulse width signal which is being generated on this board and between the rise fall time sensing circuit which is generated on the output board The gate U10 selects from normal and inverted signals to be applied to the switching transistors in the transition times generator circuit Theory of Operation 6 9 This page intentionally left blank 6 10 Theory of Operation Adjustments amp Troubleshooting 7 1 INTRODUCTION This section contains information necessary to adjust and troubleshoot the 8550 function generator and the 8551 pulse function generator WARNING The procedures described in this sec tion are for use only by qualified service personnel Do not perform these procedures unless qualified to do so M
223. t Number Part Number Vendor Code 3000 30520 27264 3000 16000 74970 0900 00700 55101 4200 00000 66958 Q1 Q7 Q8 Q25 TSTR PN3904 Q4 Q5 TSTR 2N5179 Q6 Q9 TSTR PN3906 Q10 Q11 Q15 TSTR MPS3646 02 03 012 013 016 TSTR MPS3640 Q18 Q19 Q21 Q23 TSTR 2N3866A Q17 Q20 Q22 Q24 TSTR 2N5160A 0400 00800 04713 Q14 TSTR J 109 0400 02500 17856 R13 SEL TYP 2 4K 74902 R94 R99 RES COMP 4 7 5 1 4W 0100 04R70 74902 R101 R108 RES COMP 10 5 1W 0101 0100A 74902 R77 22 5 1 4W 0100 02200 74902 R89 39 596 1 4W 0100 03900 74902 R40 R41 68 596 1 4W 0100 06800 74902 R124 82 5 1 4W 0100 08200 74902 R11 R19 R21 R114 R116 100 5 1 4W 0100 01010 74902 R18 130 596 1 4W 0100 01310 74902 R68 R96 270 5 1 4W 0100 02710 74902 R37 470 5 1 4W 0100 04710 74902 R5 R39 510 5 1 4W 0100 05110 74902 R15 560 5 1 4W 0100 05610 74902 0400 01200 04713 0400 00700 04713 0400 01340 04713 0400 00200 04713 0400 00100 04713 0400 01610 04713 A 1 2 2 1 1 2 1 5 1 2 1 2 1 4 1 6 1 6 1 4 3 2 2 3 1 3 2 2 4 2 2 2 R12 R75 R109 R110 R14 R8 R9 R25 26 R111 112 R6 R59 R60 R61 R70 72 R74 R102 R103 R106 R107 R29 R30 R51 R85 R90 R1 R42 R56 R58 R125 R120 R27 R28 R54 R93 R100 R53 R55 R62 R65 R117 R118 R122 R123 R76 R80 R50 R52 1K 5 1 4W 2 2K 5 1 4W 3 3K 5 1 4W 4 7K 5 1 4W 10K 5 1 4W 100K 5 1 4W 10 1 1 4W 24 3 1 1 4W 33 2 1 4W 1 49 9 196 61 9 196 61 9 196 1W 71 5 96 1 4W 71 5 1 2W 196
224. t the CR carriage return A command string is terminated by a Pro gram Message Terminator which tells the instrument to execute the Program Message If an illegal Program Header or Program Data is present within a Program Message the instru ment will 4 12 GPIB Operation 1 Ignore the illegal part or the Program Mes sage but will execute the rest of the Pro gram Message 2 Display an appropriate front panel error mes sage 3 Set certain bits in its status registers 4 Generate SRQ if programmed to do so Device dependent programming aspects are cov ered in paragraph 4 8 5 and 4 10 NOTE Before programming the instrument over the bus It is recommended that the instrument be set to its default values by sending an SDC or DCL over the bus See paragraph 4 8 3 for information on using the SDC command In order to send a device dependent or a common command the controller must perform the following sequence 1 Set ATN true 2 Address the Model 8550 to listen 3 Set ATN false 4 Send the command string over the data bus one byte at a time NOTE REN must be true when attempting to program the Model 8550 Device dependent commands that affect Models 8550 and 8551 are listed in Table 4 5 Common commands and queries are listed in Table 4 6 All the commands listed in the Tables 4 5 and 4 6 are covered in detail in the following 4 10 1 Operating Mode F Th
225. ta 16 DIO8 Data 17 REN Management 18 24 Gnd Ground Contacts 18 through 24 are return lines for the indicated signal lines and the cable shield is connected to contact 12 Each ground line is con nected to digital common in the Model 8550 CAUTION The voltage between IEEE common and ground must not exceed 0 V or damage may result to your instru ment 4 7 CHANGING GPIB ADDRESS The primary address of your instrument may be programmed to any value between 0 and 30 as long as the selected address is different from other devices addresses in the system This may be accomplished using a front panel programming se quence Note that the primary address of the instru ment must agree with the address specified in the controllers program NOTE The programmed primary address is briefly displayed during the power up cycle of the Model 8550 It is stored in the non volatile memory of the GPIB Operation 4 5 instrument and is retained even when power is turned off To check the present address or to enter a new one proceed as follows 1 Depress the 2nd push button once then de press the GPIB ADR push button The display will be modified to display the following GPxx Where x may be any number from to 30 2 Use the MODIFIER x11 or the x1 U push buttons for selecting a new GPIB primary address 3 To store the newly selected primary address depress EXE The instrument then resumes normal ope
226. tance is given in 5 and capacitance is given in F 20 Parts description in Table 8 2 overrides values shown on the schematic and the assembly drawings in places where part description does not match Vendor Amphenol Products Amphenol Canada Analog Devices AVX Belden Wire Inc Bourns Inc Comlinear Corporation Corcom Inc Cornell Dubilier CTS Knights Division Dale Electronics E F Johnson Company General Instruments Hamlin Harris Semiconductors HP 7 seg HP Schottkey diodes Intel Corporation International Resistor Co ITT Components Kemet Elctronics Corp Littlefuse LSI Computer Systems Address 4300 Commerce Court Lisle Illinois 60532 44 Metropolitan Road Scaborough Ont M1R 2T9 Canada One Technology Way Norwood MA 06062 Senaca Avenue Olean NewYork 14760 2200 U S highway 27 South Richmond Indiana 47374 1200 Columbia Avenue Bldg C Riveside CA 92507 4800 Wheaton Drive Fort Collins Collorado 80525 1600 Winchester Road Libertyville Illinois 150 Avenue L Newark New Jersey 07101 400 Reidmann Avenue Sandwich Illinois 60548 2064 12th Avenue Columbus Nebraska 68601 299 Johnson Avenue Waseca Minnesota 56093 600 West John Street Hicksville New York 11802 Lake Grove Streets Lake Mills Wisconsin 53551 1301 Woody Burke Road Melbourne Florida 32902 3000 Hanover Street Palo Alto California 94304 3000 Hanover Street Palo Alto California 94304 3065 Bowers Avenue Santa Clara California
227. ted burst Interrogate trigger level Interrogate trigger phase offset Interrogate dc output level Interrogate logarithmic sweep stop Interrogate sweep time Interrogate logarithmic sweep marker Interrogate linear sweep stop Interrogate linear sweep marker Interrogate pulse ramp error status Interrogate machine status Interrogate cal failure status byte A Interrogate cal failure status byte B Interrogate cal failure status byte C Response header OFF Response header ON New line LF END EOI terminator New line LF terminator END terminator No terminator Clear status command Standard event status enable command Operation complete command Recall front panel set up command Reset command Save front panel set up command Service request enable command Trigger command Wait to continue command GPIB Operation 4 15 Table 4 5 Device Dependent Command Summary continued Mode COMMON QUERIES STANDARD EVENT STATUS ENABLE REGISTER MASK CALIBRATION FAILURE STATUS BYTE A MASK CALIBRATION FAILURE STATUS BYTE B and C MASK SERVICE REQUEST ENABLE REGISTER MASK Model 8551 only Program Header and Data CAL ESE ESR SRE STB TST 5 0 5 1 5 2 5 4 5 8 5 16 5 2 5 64 5 128 through FSA16383 through FSB255 through FSC16383 SREO SRE1 SRE2 SRE4 SRE8 SRE16 SRE32 SRE128
228. ted burst N the trailing edge transition time Trail and the internal trigger period 1 Per have occurred This error bit is set true under the following conditions N x Per Trail gt 1 Per Note that in the above formula the value of N in triggered mode is set to 1 and the value of Trail in fast transition times is set to O Error 6 Bit 5 This bit indicates that an error relating to the ramp duration have occurred This error bit is set true under the following conditions Ramp Duration gt 5 us Error 7 Bit 6 This bit indicates that an error relating to the pulse width have occurred This error bit is set true under the following conditions Pulse Width 10 ns Error 8 Bit 7 This bit indicates that an error relating to the pulse width have occurred This error bit is set true under the following conditions Pulse Width gt 999 ms GPIB Operation 4 29 4 14 5 Machine Status Register STT The Machine Status Register STT is a special register which contain the present front panel setting The STT is non destructively read with the STT query The response to this query is a Numeric Response Data with the length of 11 digits These digits are numeric representation of the various Ma chine Status options as illustrated in Figure 4 6 4 15 FRONT PANEL ERROR MESSAGES The process of programming the Model 8550 involves the proper use of syntax Syntax is defined as the orderly or systema
229. that are related to the same header Program Header Separator gt Separates the header from any associated Program Data Program Message Terminator Terminates Program Message Command Program Header Specifies function operation Used with any associated Program Data elements Query Program Header gt Similar to Command Program Header except a query indicator shows that a response is expected from the device Character Program Data A data type suitable for sending short mnemonic data generally where a numeric data type is not suitable Decimal Numeric Program Data A data type suitable for sending decimal integers or decimal fractions with or without exponents Suffix Program Data An optional field following Decimal Numeric Program Data used to indicate associated multipliers and units NonDecimal Numeric Program Data A data type suitable for sending integer numeric repre sentation in base 16 8 or 2 Useful for data that is more easily interpreted when directly expressed in a non decimal format String Program Data A data type suitable for sending 7 bit ASCII character strings where the content needs to be Hidden by delimiters Arbitrary Block Program Data A data type suitable for sending blocks of arbitrary 8 bit informa tion Expression Program data data type suitable for sending data that is elevated as one or more non expression data elements before furth
230. that are required Recalled front panel set ups are limited to 30 3 19 2 1 Using The Recall Mode Model 8550 8551 employs a special recall mode which permits ascended or descended scroll through a number of set ups by pressing either the MODIFIER x1 1 or x1 U push buttons respectively This mode is especially useful for repetitive procedures such as calibration and performance tests To set the function generator for operation in its recall mode proceed as follows 1 Depress the 2nd push button and observe that the display is modified to indicate the following 2nd appears flashing 2 Depress the RCL MODE push button and observe that the display is modified to indicate the following C 00 The instrument is now set to operate in its recall mode The display is first updated with the parameters which were stored in memory cell 00 3 Use the MODIFIER x1 f or x1 J to scroll through the memory bank 4 Depress any other front panel push button to exit this function and to return to normal display operation 3 20 CHANGING THE GPIB ADDRESS GPIB address is modified using front panel program ming The GPIB address is stored in the non volatile memory therefore conventional address switches are not provided Detailed instructions how to change the GPIB address are given in Paragraph 4 7 3 21 CHANGING EMULATION MODE TO HP Models 8550 and 8551 can be made fully compatible with HP Model 8116A device dep
231. the following 4 11 1 Functional Element Summary Response Message Represents a sequence of one or more Response Message Unit elements separated by Response Message Unit Terminator elements Response Message Unit gt Represents a single message unit sent from the device Response Data Represents any of the eleven different Response Data types Response Message Unit Separator gt Separates Response Message Unit elements from one an other in a Response Message Response Data gt Separates sequen tial Response Data elements that are related to the same header or to each other Response Header Separator gt Separates the header from the associated lt Response Data gt lt Response Message Terminator gt Terminates a lt Response Message gt lt Response Header gt Specifies the function of the associated lt Response Data gt element s Alpha characters mnemonically indicate the function lt Character Response Data gt A data type suitable for sending short mnemonic character strings Gen erally used when a numeric data type is not suitable lt Decimal Numeric Response Data gt A data type response suitable for sending decimal integers or decimal fractions with or without exponents lt NonDecimal Numeric Response Data gt A data type suitable for sending integer numeric repre sentation in base 16 8 or 2 Useful for data that is more easily interpreted when directly
232. their associated compo nents The loop amplifier is made of operational amplifier U32 The phase locking filtering capacitor resistor networks are selected by a multiple analog switch U30 which connects the required feedback network to the loop amplifier The phase locking detector is comprised of a window comparator U31a 0310 R87 R88 R89 and level shifter made of and R66 6 5 5 Counter Conditioning Circuit Model 8550 8551 employs a built in counter which is used in a number of applications such as frequency accuracy control automatic calibration measure fre 6 6 Theory of Operation quency of an external signal and more The counter circuit itself is located on the CPU board assembly however signal conditioning and routing to the counter from the different parts of the instrument is controlled by circuits on the calibration board The various parts of the conditioning circuits are described in the following The counter input may receive its signal from a number of sources from the trigger input from the VCO from the phase sensing circuit U38c and U34a and from the pulse width board Model 8551 only The signal for the counter input is selected by a selector which is made of gates U39a 0396 U39c and U39d Frequencies up to 1 MHz are routed directly to the counter input 040 divides signals above 1 MHz by 10 to reduce maximum frequency that may reach the counter input to 5 MHz The signals for the counter cir
233. tic arrangement of programming commands or languages The Model 8550 must receive valid commands with proper syntax or it will 1 Ignore the part of the Program Message Unit gt in which the invalid command appears 2 Set appropriate bits in the Standard Event Status Register 3 Generate an SRQ if programmed to do so 4 Display an appropriate front panel message 4 15 1 ILI Illegal Instruction Error An ILI error results when the Model 8550 receives an invalid Program Header such as AMPL1 00 This command is invalid because the real command should read AMP1 00 When such an illegal Program Header is detected by the instrument the following message will be displayed on the Model 8550 for about one second ILI 4 15 2 ILP Illegal Parameter Error An ILP error occurs when the Numeric Data parameter associated with a legal Program Header command is not valid For example the command AMP100E 0 is not a valid option because the required amplitude is outside the legal limits of the model 8550 When such an illegal Numeric Data is detected the following message will be displayed on the Model 8550 for about one second Figure 4 6 Machine Status String STT Interpretation ILP 4 16 GPIB COMPATIBILITY WITH HP MODEL 8116A Model 8551 can be made fully compatible with HP model 8116A device dependent command set This built in option saves a lot of valuable programming time when replacing model 8116A w
234. tion or degradation of parts and assemblies Use ordinary 60 40 solder and 35 to 40 watt pencil type soldering iron on the circuit board The tip of the iron should be clean and properly tinned for best heat transfer to the solder joint A higher wattage soldering iron may separate the circuit from the base material Keep the soldering iron in contact with the PC board for a minimum time to avoid damage to the components or printed conductors To desolder components use a commercial solder sipper or better solder removing SOLDER WICK size 3 Always replace a component with its exact duplicate as specified in the parts list 5 8 PERFORMANCE CHECKS The following performance checks verify proper op eration of the instrument and should normally be used 1 As part of incoming inspection of instrument specifications 2 As part of troubleshooting procedure 3 After any repair or adjustment before returning instrument to regular service 5 8 1 Environmental Conditions Tests should be performed under laboratory conditions having an ambient temperature of 25 5 and a relative humidity of less than 855096 If the instrument has been subjected to conditions outside these ranges allow at least one additional hour for the instrument to stabilize before beginning the adjustment procedure Always perform a self calibration sequence before commencing with the performance checks The self calibration if executed without any
235. tiple data elements are sent The Response Data Separator gt is defined as 4 11 2 3 Response Header Separator The Response Header gt separates the Response Header from the Response Data The Response Header Separator gt is defined as Space 4 11 3 Response Message Terminator The Response Message Terminator element s func tion is to terminate a sequence of one or more Response Message Unit elements There are three possible Response Message Terminator elements 1 NL new line 2 NL END and 3 END EOI NL is defined as a single ASCll encoded byte OA 10 decimal Leading White Space elements are not permitted The instrument interprets any and all of the three terminators as semantically equivalent No alternative encoding are allowed Note that IEEE P981 amendment forbids the use of CR as a Re sponse Message Terminator element This is be cause some controller treat as the end of transmission and leave the LF character in the unit thereby creating an error in the controller 4 11 4 Response Header The Response Header is available for use by the device designer for device specific responses It may be used for example to create responses in directly resendable Program Message Unit format or to identify response data to the controller There are three defined Response Header elements Simple Response Header Compound Respon
236. to 500 795mV Within 800mV level window 7 95V Within a 8 00V level window 180 20 00ns Model 8551 only 10 0ns Model 8551 only 8550 Model 8551 only 8ns Model 8551 only 8ns Model 8551 only 20us 4000 10 0V 90 8 00V Model 8550 only 50 00MHz Model 8550 only 5000 display counts Model 8550 only 999s Model 8550 only 50 00MHz Model 8550 only 5000 display counts Model 8550 only 30 30 Tabel 3 2 Front Panel Parameter Entry Limits Operating Instructions 3 9 1 Depress the POWER switch once to turn power on and leave the instrument on at least 30 minutes until the internal circuits reach thermal equilibrium 2 Depress the two AUTOCAL push buttons si multaneously and observe that the generator displays the following CAL The appears blinking indicating that the in strument has not yet commenced with its calibration routine Depress any front panel push button to quit the auto calibration sequence and return to normal operation Depressing EXE initiates the calibration routine The blinking question mark is then replaced by a moving bar The bar circles as long as the calibration routine is in process Following successful execution of its internal cali bration the instrument resumes normal operation If self calibration fails the generator proceeds with displaying a failure list Recalling and terminating the failure list display is described in the succeeding paragraph Analyzing and int
237. to 9096 of amplitude 5 ns typical 595 0 to 1V into 500 0 to 2V open circuit lt 3ns into 500 595 Output Normal or Disabled 500 1 20 0mV to 32 0Vp p into open circuit 10 0mV to 16 0Vp p into 500 3 digits 4 of reading from 10 0mV to 16 0V General Information 1 3 Table 1 1 Model 8550 8551 Specifications continued Level Windows 800mV for amplitude from 10 0mV to 99 9mV 8V for amplitude from 100mV to 16 0V Output Protection Protected against continuous short to case ground Offset Resolution 3 digits Range Offset and amplitude are independently adjustable within level windows of 800mV and 8 00V Within 800mV 0 to 795 Within 8V 0 to 7 95V Accuracy 1 of setting 1 of amplitude 2mV within 800mV 1 of setting 1 of amplitude 2mV within 8V DC CHARACTERISTICS Model 8550 only Range Variable from 16 0V to 16 0V into open circuit 8 00V to 8 00V into 500 Resolution 3 digits with exponent Accuracy 1 of reading 100 TRIGGERING CHARACTERISTICS Trigger Input Via TRIG REF BNC terminal Impedance 10KQ 1595 Sensitivity 500mVp p Max Input Voltage 20V Min Pulsewidth 20ns Slope Positive going leading edge Source Manual front panel push button internal or external stimulant Modes Normal Continuous waveform is generated Triggered Each input cycle generates a single output cycle Internal Trigger An internal t
238. tput connector The step attenuator circuit is made of three sets of phi shaped resistors R50 through R58 The resistors are switched in and out of the attenuator with relays K1 K2 and The post attenuator is a 20dB attenuator which is connected between output of the power amplifier and the output connector This post attenuator is made of K5 R120 R121 and R125 6 6 5 Power Amplifier Circuit Refer to the schematics at the end of this manual throughout the following description The output am plifier is a wideband current feedback type amplifier The signal from the step attenuators is fed to the power amplifier through the emitter of transistors Q11 and Q12 which are connected in a cascadable fashion with Q10 and Q13 respectively Q15 and Q16 are emitter followers that drive the gain stage made of Q17 and Q18 Q19 and Q20 buffer the amplified signal for the final class B amplifier stage which is made of power transistors Q21 through Q24 Note that the power transistors are mounted on special heat sinks mounted on a bracket which is connected to the side support to remove the heat stress from these transistors Q25 with R95 and R96 set the quiscent current for the power transistors The current feedback is extracted from the output through R104 R105 R78 and R79 and is fed to the input transistors Q11 and Q12 The input bias current of the power amplifier is compensated by an operational amplifier U14 a buffer made of Q
239. tput connector is connected to an high impedance circuit the actual amplitude level at the output connector is doubled Amplitude control has no effect on the amplitude level at the SYNC output connector The amplitude parameter may be programmed within the range of 10 0mV to 16 0V Preset value is set to 1 00V OFST DC offset of the selected waveform at the main output connector Similarly to the amplitude the offset parameter is specified and accurately controlled only when the output is terminated with 500 Offset control has no effect on the SYNC output connector The offset parameter may be pro grammed within the range of 0 00mV to 7 95V Preset value is set to OmV 2 SWEEP STOP Defines the sweep stop frequency When the function generator is set to operate with one of its sweep modes the waveform at the output con nector sweeps from frequency set by the FREQ setting to that set by the STOP frequency In several sweep modes sweep stop may change its function to sweep start The programmed frequency retains its value at both SYNC and the main output con nectors If the instrument is set to operate in loga rithmic sweep mode the sweep stop parameter may be programmed within the range of 10 00mHz to 50 00MHz In linear sweep mode the sweep stop parameter may only programmed within three decades from the start frequency setting Preset value is set to 9 000KHz TIME In linear sweep mode sweep time de termines the time
240. tru ments on the bus for remote operation 4 EOI End Or Identify The EOI line is used to send the EOI command that usually terminates a multi byte transfer sequence 5 SRQ Service Request the SRQ line is set low by a device when it requires service from the controller 4 3 2 Handshake Lines The bus uses three handshake lines that operate in an interlocked sequence This method assures reliable data transfer regardless of the transfer rate Generally data transfer will occur at a rate determined by the slowest active device on the bus One of the handshake lines is controlled by the data source while the remaining two lines are con trolled by accepting devices The three bus handshake lines are 1 DAV Data Valid The source controls the state of the DAV line 2 NRFD Not Ready For Data the acceptor controls the state of the NRFD line 3 NDAC Not Data Accepted the acceptor also controls the NDAC line The complete handshake sequence for one data byte is shown in Figure 4 2 Once data is on the bus the source checks to see that NRFD is high indicating that all devices on the bus are ready for data At the same time NDAC should be low from the previous byte transfer If these conditions are not met the source must then wait until the NRFD and NDAC lines have the correct status If the source is controller NRFD and NDAC must remain stable for at least 100 ns after ATN is set low Because of the possibi
241. ts sweep cycle continuously SWEEP DN The sweep down mode is similar to the sweep up mode except that the output wave form when triggered sweeps from frequency set by the sweep stop STOP parameter to frequency set by the sweep start FREQ parameter Sweep time is determined by the TIME parameter At the end of the sweep the output waveform remains at the start frequency Following another trigger the output jumps quickly to its stop frequency and the above cycle is repeated In normal mode the generator repeats its sweep cycle continuously SWEEP UP DN The function generator when triggered sweeps from value set by the FREQ parameter to value set by the STOP parameter and back to the FREQ value Sweep time is doubled than the displayed TIME parameter At the end of the sweep the output waveform remains at the start frequency Following another trigger the above cycle is repeated In normal mode the generator repeats its sweep cycle continuously SWEEP DN UP The sweep down mode is similar to the sweep up mode except that the output waveform when triggered sweeps from value set by the STOP parameter to value set by the FREQ parameter and back to the STOP value Sweep time is doubled than the displayed TIME parameter At the end of the sweep the output waveform remains at the stop frequency Following another trigger the above cycle is repeated In normal mode the generator repeats its sweep cycle continuously Selectin
242. tups o s Sak 3 19 2 1 Using The Recall Mode 3 20 Changing The GPIB Address 3 21 Changing Emulation Mode to HP SECTION 4 GPIB PROGRAMMING 4 1 Introduction uem Rem te oe eee ee p 4 2 Bus Description s sso a ee do des 4 3 IEEE 488 Bus sc a us ERE 4 3 1 Bus Management 4 3 2 Handshake Lines au ex xm ap ub te REB e En 4 3 3 PL ott Bata Rey Ban Sark e eee Go Etats ii Contents 4 4 Interface Function Codes s s ss mos gon bo d 4 4 4 5 Software Considerations 4 4 4 6 Hardware Consideration 4 5 4 6 1 Typical Controlled Systems 4 5 4 6 2 COnnectlons Dude E Ee d 4 5 4 7 Changing GPIB Address 4 5 4 8 Bus Gommands ox uy iue d 4 6 4 8 1 Uniline Commands 4 6 4 8 2 Universal Multiline Commands 4 7 4 8 3 Addressed Commands 4 8 4 8 4 Unaddress Commands 4 8 4 8 5 Device Dependent 5 4 9 4
243. valent pulse width to be measured by the counter The results are then compared by the CPU circuit to reference values and translated to correcting factors which are later being used for accuracy correction Theory of Operation 6 7 6 7 MAIN BOARD The main board assembly contains the power supply calibration references reference digital to analog circuits connectors for the plug in boards and the interconnections between the various boards which are used on Models 8550 and Model 8551 The various parts that are laid on the main board are described in the following Complete and detailed schematics of this board are located at the end of this manual 6 7 1 Power Supply Circuit Refer to the power supply schematic at the end of this manual for the following discussions The power supply consists of a main power transformer three bridge rectifiers four integrated regulators 5 V and 5 2 V linear power supply The LINE fuse and the Line Selector are accessible at the rear panel The LINE VOLTAGE SELECT switch select 115V or 230V operation CR7 is used as a full wave rectifier to provide a sufficient DC voltage for the 24 V and 24 V regulators U9 and U10 respectively CR6 is used as a full wave rectifier to provide a sufficient DC voltage for the 15 V and 15 V regulators U6 and 07 respectively The 5 V linear power supply is made of power transistor Q9 control amplifier U8b Q4 R25 R28 and overload protection Q5 and R
244. wave within exactly 6 vertical divisions 3 Change 8550 Frequency setting to 9 999 MHz Verify that peak to peak of the displayed sinewave is greater than 5 8 divisions 4 Change 8550 Frequency setting to 50 00 MHz Verify that peak to peak of the displayed sinewave is greater than 5 1 divisions 5 9 8 External Trig Gate Burst Characteristics Specifications Triggered Each positive going transition at the front panel TRIG IN connector stimulates the 8550 to generate one complete output waveform Gated External signal at the TRIG IN connector enables the 8550 output Last cycle of output waveform always completed Burst Each positive going transition at the front panel TRIG IN connector stimulates the 8550 to generate a burst of preselected number of cycles Equipment Pulse function generator oscilloscope 5 9 8 1 External Trigger 1 Set 8550 as follows CONTROL POSITION Frequency 1 000 MHz Trigger Mode TRIG D 2 Set external pulse function generator period to 10us and 4 V positive pulse and connect its output to the 8550 TRIG IN BNC connector Set oscilloscope and verify on the oscilloscope that 8550 outputs a triggered signal Leave external pulse generator con nected to the 8550 for the next test 5 9 8 2 External Gate 1 Set 8550 as follows CONTROL POSITION Frequency 1 000 MHz Trigger Mode GATED 2 Set oscilloscope and verify on the oscilloscope that 8550 outputs a gated signal Leave externa
245. ween these pulses to the reference clock The result is compared to the required accuracy If deviation is sensed the CPU sends correcting data to the current generator circuit 6 3 3 IEEE 488 Interface Bus GPIB The instrument has a built in IEEE 488 interface bus that permits remote control through a system con troller The IEEE interface is made of U15 General Purpose Interface Adapter U16 and U17 interface bus drivers On the CPU side of the GPIB data transmission is handled much like any other bus transaction The output of the U15 is standard GPIB format and is buffered by the two GPIB drivers U16 and U17 The bus divers are necessary for enhancing the drive capability of the interface Up to 15 devices may be connected in parallel 6 4 V C O BOARD The following paragraphs contain descriptions of the various circuit that are available on the VCO board The circuits that are discussed here are the voltage controlled oscillator and the clamp circuit the current generator circuit the timing capacitors and the ca pacitance multiplier circuit the sine shaper circuit the trigger circuit the SYNC out circuit and the auxiliary circuits Complete and detailed schematics of this board are located at the end of this manual 6 4 1 Voltage Controlled Oscillator The VCO is comprised of a comparator U13 FET buffer Q12 current switches Q13 Q14 Q19 and Q20 and timing range capacitors C21 through C24 and C36
246. weep direction may be programmed by sending one of the following commands S0 Sweep from start frequency to stop Fre quency up 51 Sweep from stop frequency to start Fre quency down S2 Sweep from start frequency to stop Fre quency to start frequency up down S3 Sweep from stop frequency to start Fre quency to stop frequency down up 4 10 3 Trigger Modes M The trigger mode command gives the user control over the output stimulant of the Model 8550 There are a number of acceptable external sources for stimulating the output of the function generator The instrument may also be set to operate in continuous mode or with having an internal trigger source The generator may be programmed to accept either an external stimulant or an internal stimulant Program the Model 8550 to one of the trigger modes by sending one of the following commands M1 Normal continuous mode M2 External trigger M3 External gate M4 External burst M5 Internal trigger M6 Internal burst 4 10 4 Control Modes CT Model 8550 provides three control modes FM AM and VCO Model 8551 offers PWM Am and VCO The control mode command gives the user control over the control mode of the function generator Program the Model 8550 to one of the control modes by sending one of the following commands CTO Normal operating mode CT1 FM mode model 8550 only CT2 AM mode CT3 PWM mode model 8551 only CT4 VCO mode 4 10 5
247. weep output voltage is generated by the digital to analog converter U19 operational amplifier U18a and their associated components The marker output signal is generated by an operational amplifier U18b 6 5 3 Trigger Input Circuit The trigger input circuit receives external stimulating signal shapes it and adjusts the internal threshold amplitude to the required level The external signal is received through the TRIG IN BNC connector and is routed through R40 to the comparator U26 and its associated components CR1 and CR2 are used as protection against overloading the comparator input The threshold level is generated by a digital to analog converter 1 operational amplifier U4b and their associated components 6 5 4 Phase Locking Circuit Model 8550 8551 is capable of locking on an external signal and automatically adjust itself to the frequency and the phase of the external signal The various parts of the locking circuit are described in the following U37a U37b and U37c is a signal selector which selects the signal to be applied to the phase detector input The square wave signal from the VCO is applied to the second input of the phase detector through U38a The phase detector is comprised of a flip flops U33a and U33b gate U37d and their associated components The phase lock loop also include a pump charge generator which is made of current switches Q5 through Q8 current generators made of Q9 and Q10 and
248. which control the shape of the wave form at the output connector Modification of a specific parameter is simply done by pressing the push button below the requested parameter until the light behind the required parameter illuminates At this time the numeric readout displayed a value plus an exponent For example a FREQ readout of 10 00 exp 3 tells us that the output waveform is programmed to have a frequency of 10 00 KHz Limits for each parameter are given in Table 3 2 The parameter can be modified using the MODIFIER and the RANGE push buttons The parameters which can be modified are marked on the front panel as follows Function parameters FREQ Frequency AMPL Amplitude OFST Offset PHASE PLL offset Model 8551 Sweep parameters Model 8550 only STOP Sweep stop frequency TIME Sweep time MARK Marker frequency Pulse parameters Model 8551 only PER Period WIDTH Pulse width DUTY Duty cycle Phase offset Parameters PLL PLL offset Model 8550 TRIG Trigger phase offset Transition times parameters Model 8551 only LEAD Leading edge TRAIL Trailing edge Trigger parameters PER Int trigger period BUR Burst count LEVEL Trigger level PHASE Trig phase Model 8550 addition some parameters are accessible through the 2nd button These parameters are STORE Store address RECALL Recall address SWP MODE Sweep mode direction GPIB ADR GPIB address 3 12
249. ystem comprises a controller and one Model 8550 The controller is used to send commands to the instrument which sends data back to the controller The system becomes more complex when addi tional instruments are added Depending on program ming all data may be routed through the controller or it may be transmitted directly from one instrument to another 4 6 2 Connections The instrument is connected to the bus through an IEEE 488 2 connector This connector is designed to be stacked to allow a number of parallel connec tions on one instrument NOTE To avoid possible mechanical dam age it is recommended that no more than three connectors be stacked on any one instrument Otherwise the resulting strain may cause internal damage to the connectors The IEEE 488 2 bus is limited to a maximum of 15 devices including the controller Also the maximum cable length is 20 meters Failure to observe these limits will probably re sult in erratic bus operation Custom cables may be con structed using the information in Table 4 2 Table 4 2 also lists the contact assignments for the various bus lines Table 4 2 IEEE 488 Contact Designations Contact IEEE 488 Number Designation Type 1 DIO1 Data 2 DIO2 Data 3 DIO3 Data 4 0104 Data 5 EOI Management 6 DAV Handshake 7 NRFD Handshake 8 NDAC Handshake 9 IFC Management 10 SRQ Management 11 ATN Management 12 SHIELD Ground 13 DIO5 Data 14 DIO6 Data 15 DIO7 Da

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