Sweep Generator Diagram | Tektronix 1705A manual

Theory of Operation

Sweep Generator

Diagram 3

This schematic contains the free-running Ramp Generator, Switchable Gain Control (SPAN/DIV), Sweep Shapers, Marker Generator, and the Z-Axis (Brightness) control.

Ramp Generator U24 is the Ramp Generator; U24B is configured as an integrator and U24A is used as a comparator. C40 is the integration capacitor and is charged by current from the front-panel SWEEP SPEED control. The ramp integrates in the positive direction from -2 volts to +2 volts. At +2 V the output of U24A trips to the positive power supply voltage (+5 V) and causes C40 to ramp down through CR24 and R151. The value of R151 determines the amount of time required to discharge C40 (retrace time). The power supply for U24 is +5 and -11.8 volts. The output swing of U24A is nearly to these supply values. The Ramp Generator output, through R142, drives Q6 through U23B in the Z-Axis control to provide retrace blanking. CR21 limits the output swing in the negative direction to -0.7 volts.

Gain Control (SPAN/DIV) The Ramp Generator output (U24B, pin 7) drives the Horizontal Deflection Amplifier and the Gain Control (SPAN/DIV) switching, U20. Each switch in U20 selects a different value of Ri for operational amplifier U18A. The gain is maximum at FULL (50 MHz per division) and minimum at 100 kHz per division. The output of U18A is a negative-going ramp that drives the Sweep Shapers.

Sweep Shapers U16B and C form the Sweep Shaper that drives the L-BAND VCO; U16A and D drive the 70 MHz VCO. The Sweep Shapers pre-distort the VCO driving ramps to compensate for the inherent nonlinearity of the VCO. The shapers have adjustable break points so that gain at each can be individually adjusted. The

70 MHz shaper has four adjustments, R48, R49, R55, R56; and the L-BAND shaper has six adjustments, R35, R51, R58, R75, R81, and R82. Figure 4-1 shows the area of control for the various adjustments on the 1705A L-Band display, when a comb signal is applied.

1705A Spectrum Monitor

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Tektronix 1705A instruction manual Sweep Generator Diagram

Contents

1705A Spectrum Monitor SN B040000 and Above 070-8222-08 Table of Contents Theory of Operation InstallationTable of Contents Checks and Adjustments 1705A Spectrum Monitor Iii Maintenance Options Replaceable Mechanical Parts 10-1 Replaceable Electrical PartsReplaceable Electrical Parts List of Figures Simulation of a 1705A Full SPAN/DIV display Considerations for custom installation of an instrument 1705A Spectrum Monitor Vii List of Tables Viii General Safety Summary General Safety Summary Service Safety Summary Service Safety Summary Xii Introduction InstallationPreface Replaceable Mechanical Parts USA Contacting TektronixPreface Preface Xvi Introduction Page Typical Configurations Section Introduction Accessories OptionsIntroduction #73 Safety Information Optional Accessories Full Spectrum DisplaySPAN/DIV CRT Display Power SourceIntroduction Spectrum Display Introduction Environmental Characteristics Physical CharacteristicsCertifications and Compliances EMC Introduction Certifications and Compliances CAT Meters Applications SUN Satellite Earth Using the 1705A for Satellite Communication Band Input Signals Vancouver BC Seattle Portland Helena Boise SAN FranciscoLOS Angeles SAN Diego Zeroing in on a Satellite Tek 12.20 GHZ Horizontal Vertical Polarization Frequency and Number Down Link Transponder Looking at Exciters with the 70 MHz Input GHZ Miscellaneous Uses for the 1705A LNB OUT BandSplitter Input Operating Instructions Page Front-panel Controls and Indicators Section Operating Instructions Position Power Operating InstructionsFilter Input Display Variable control that adjusts the display brightness SPAN/DIV Rear- Panel Connectors Position Holder for the instrument’s mains fuse Spectrum Monitor Powering- up 1400 MHZ Measurement Graticule 1705A graticule scale Reading in dB Voltage Ratio Power Ratio Voltage Ratio Power RatioOperating Instructions DB Reference Reading in dB 75Ω 50Ω Operating Instructions DBm to v Conversion Reading in dBm Frequency Scale = 10 Divisions Sweep Length = 12 Divisions Minimum Maximum FrequencyMID MHZ Center Frequency Readout70 MHZ 1400 MHZ Point on Trace That Corresponds to Center Frequency Tuned AT this Point Customizing Frequency Readout Readout Mode Offset AdjustMain Menu Readout Position 12.00 GHZ Basic Operating Procedure Locating Ku- Band Satellites City Satcom K2 G-STAR 1705A Spectrum Monitor Operating Instructions Page Page Installation Page Section Installation Electrical Installation Mechanical Installation InstallationLNB Power Band Input OFF Cabinet Options 250 875105 130 1700F02 portable cabinet dimensions Cabinetizing Cabinet Securing Screws A WFM7F05 with a blank front panel 1700F06 1700F07 1705A Spectrum Monitor Theory of Operation Page Overview Block DiagramSection Theory of Operation Theory of Operation Front Panel Diagram RF Input Diagram If Amplifier Diagram Resolution Filter and Log Detector Sweep Generator Diagram Start Display Deflection Amplifiers Diagram Vertical Deflection Amplifier Microprocessor Diagram Front Panel Diagram LOW Load Average High Load Low Voltage Power Supply Diagram Pulse Width Modulator Theory of Operation High Voltage Power Supply Diagram Axis Amplifier CRT The pinout for the CRT is shown in Figure Pinout of the CRT Socket 1705A Spectrum Monitor Theory of Operation Checks and Adjustments Page Electrical Instruments Section Checks And AdjustmentsRecommended Equipment List Auxiliary Equipment Performance Check Short-Form ProcedureChecks and Adjustments SMA Male-to-bnc Female Adapter 1705A Spectrum Monitor Long Form Procedure Checks and Adjustments Preliminary Control Settings Page Marker Here Marker is +/-- 1 Minor Division from Here Checks and Adjustments 1705A Spectrum Monitor Page Variable Autotransformer L-BAND Input Disregard Marker Here Graticule Line UHF Sine Wave Generator Page End of the Performance Check Procedure Adjustment Procedure Short- Form Procedure Preliminary Setup Video SPAN/DIV Full Center Frequency A1 PWR Sply BD A3 Main BDFront Tek Strap Remove the shorting strap 1705A Spectrum MonitorShorting 1705A Spectrum Monitor Page 1705A Spectrum Monitor Page 1705A Spectrum Monitor End of Adjustment Procedure Checks and Adjustments Maintenance Page Section Maintenance Cleaning Schottky Signal LOW Power SchottCmos ECL Troubleshooting Diagnostic Routines Nonvolatile 2444 RAM Test Reading Data Stored AT 60H to 7F in Processor Error Cannot Read or Write Press Input KEY to Exit Troubleshooting Aids Circuit board assembly locations Major Assembly Interconnection ROW B ROW a PIN Power Supply Troubleshooting Procedure Power Supply Fault Symptoms Maintenance Power Supply Fault Symptoms Low Volts Supply Maintenance Rectifier/Switcher Check High Volts Supply Maintenance High Volts Supply Fault Symptoms Focus Amplifier CheckAxis Amplifier Check Grid Drive Check High Voltage Oscillator Check CRT Voltage Check Corrective Maintenance Obtaining Replacement Parts Bezel Removal Mechanical Disassembly/AssemblyMaintenance Test Selectable Components Graticule Light Removal and Replacement Removal of the CRT Replacing the CRT Removal of Front- Panel Assembly Removal of the Rear Panel Removing the L- Band Tuner Removal Replacement of the Main Board Removal Replacement of the Power Supply Board Removing the LNB Power Supply Board Front Repackaging 1705A Spectrum Monitor Options Page Field Upgrade Kits Power Cord OptionsPower Cord Options Description of power cord Section Options Ordering Replaceable Electrical Parts Page Parts Ordering Information Using the Replaceable Electrical Parts ListSection Replaceable Electrical Parts Column Descriptions Tektronix Part NoColumn Column 3 Spectrum Control INC Weight ST Cross Index MFR. Code Number to ManufacturerAMP INC Fulling Mill Harrisburg PA MSD INC Orange ST DARLINGTON, SC Zman & Associates Sobudai Zawa Kanagawa 228 JapanChrome Shibaura Tokyo Japan 2ND Floor NEW Kyoei MINATO-KU Wilhelm Westerman Circuit BD Assypower SUPPLY, 1705A Circuit BD ASSY18V Power SupplyCircuit BD Assyfront Panel Circuit BD Assymain Board ASSY,1705A IAL,MI CAP,FXD,PLSTC100PF,5%,1600VDC/500VACIN,BULK CAP,FXD,CER DI470PF,20%,100V TUBULAR,MI LAMP,GLOW135V MAX,1.9MA,C2A-T,WIRE Lead A1DS1A1DS2 A1DS3 SQ,TOP Adjustbulk SQ,SIDE ADJUSTT&RRES,FXD,CMPSN1.5M OHM,5%,1W RES,FXD,CMPSN2.2M OHM,5%,0.5W RES,FXD,FILM5K OHM,0.1%,0.2W,TC=T9 IAL,T&R,SMALL BodyREELED,SMALL Body RES,FXDMETAL FILM,100K OHM,1%,0.2W,TC=100 SQ,TOP ADJUST,T&R WIRED,1705ARES,THERMAL5 OHM,10%,7A/DEG C RES,FXD,CMPSN2.4K OHM,5%,2W LED ASSYDIR1 Part of A2DS313CA ASSY,SP,ELEC34,26 AWG,5.0 L RES,VAR,PNLCP,20K OHM,20%,0.5W,LINEAR,W BUS,CNDCT PLATE,ELEC Shldcircuit BoardSHIELD,ELECCIRCUIT Board SHIELD,ELEC1705A,BRS CAP,FXD,ELCTLT33UF,+50-20%,35WVDC UVX1H330MAACAP,VAR,CER DI9-45PF,200V CAP,VAR,PLSTC1-3.5PF,500V CAP,FXD,MICA DI98PF,5%,500V A3CR1A3CR2 DIO,SIGFAST RCVRY70V,200MA,100NS,COM A3FL1 FLTR,BANDPASSA3FL2 A3FL3 COIL,RFFIXED,45NH COIL,RFFIXED,15NHCOIL,RFFIXED,64UH COIL,RFFIXED,505NH RES NTWK,FXD,FI10K OHM,20%,9RES ADJUSTT&RGF06UT 2K GF06UT 5K RES,FXD,FILM3.4K OHM,1%,0.2W,TC=T0 RES,FXD,FILM115K OHM,1%,0.2W,TC=T0RES,FXD,FILM237K OHM,1%,0.2W,TC=T0 RES,FXD,FILM7.5K OHM,1%,0.2W,TC=T0 RES,VAR,NONWWTRMR,250 OHM,20%,0.5W LIN RES,FXD,FILM1M OHM.1%,0.2W,TC=T0 PercentCRB20FXE1K62 CRB20FXE9K35 RES,FXD,FILM2.1K OHM,1%,0.2W,TC=T0 RES,VAR,NONWWTRMR,100 OHM,20%,0.5W LINRES,FXD,WW6.3K OHM,1%,3W CRB20FXE210E GF06UT 1K RES,FXD,FILM187K OHM,1%,0.2W,TC=T0 Loss 10DB,PKG 7.2MM SQ,6.8MM HIIC,CONVCMOS,A/D8-BIT,32US,SAR,DIFF IN,SER MICROCKT,DGTLMICROCOMPUTER,8 BIT IC,MISCCMOS,ANALOG Swquad SPST,100 IC,LINBIPOLAR,AMPLRF AMP,20DBIC,DGTLTTL,BFR/DRVRHEX INV, OC, HI MIXER,FREQ1-500MHZ CONN,BOXSHUNT/SHORTINGFEM,STR,1 X 2,0.1 CTR,0.385 H,30 GLD,BLK,JUMPERTAIL,30 GLD IAL,MI,T&R RES,FXD,FILM267K OHM,1%,0.2W,TC=T0 RES,FXD,WW1 OHM,5%,2WOrder by Desc RES,FXD,CMPSN1K OHM,5%,0.50W CONN,HDRPCB/WIREWRAP,MALE,STR,1 X 7,0.15 CONN,HDRPCB/WIREWRAP,MALE,STR,1 X 4,0.150CORE,EMTOROID,FERRITE COIL,RFFIXED,150NH A10SKT1 Controlled 0LUA3CONN,RF Plug CA ASSY,SP Replaceable Electrical Parts Diagrams/Circuit Board Illustrations Page Diagrams/Circuit Board Illustrations SymbolsAssembly Numbers Component ValuesPage 1705A Spectrum Monitor With cross-references to schematic diagrams 1, 2, 3, 4, A3 Main Board Component Locator A3 Main Board A5 70 MHz Tuner Board Schematic Diagram 1 Component Locator Chart Local Oscillator 1705A Spectrum Monitor RF Input Schematic Diagram 2 Component Locator Chart Resolution Filter & LOG Detector 1705A Spectrum Monitor If Amplifier Schematic Diagram 3 Component Locator Chart Band Linearity Ramp GeneratorMarker Generator Schematic Diagram 4 Component Locator Chart Deflection AmplifierFilter Buffers Schematic Diagram 5 Component Locator Chart 1705A Spectrum Monitor MicroprocessorMicroprocessor Trace Schematic Diagram 6 Component Locator Chart 1705A Spectrum Monitor Front Panel & 18V Supply A2 Front Panel Board See Parts List for Effective Serial Number Ranges A1 Power Supply BoardA1 Power Supply Board Component Locator Switcher ErrorLine Rectifier Output Filters Schematic Diagram 8 Component Locator Chart A10 CRT Socket Board Front of Board Error AMP 1705A Spectrum Monitor High Volts Power SupplyHV OSC Grid DrivePage Replaceable Mechanical Parts Page Using the Replaceable Mechanical Parts List Section Replaceable Mechanical Parts Qty Column Replaceable Mechanical PartsThis indicates the quantity of mechanical parts used Indicates actual manufacturer’s part number Panduit Corp Ridgeland RichcoCHICAGO, IL Nelson Name Plate CO Casitas Circuit BD Assypower Supply See A1 Repl Mounting Parts COVER,HOUSINGALUMINUMFRAME,CRTBEZEL SCREW,MACHINE6-32 X 0.875,PNH,SST HOUSING,CKT Bdaluminum FRAME,CHASSISSAFETY ControlledSCREW,MACHINE6-32 X 0.188,PNH,STL IN/OUT See A6 Repl Mounting Parts Standard Accessories CLAMP,LOOP0.375 ID,PLASTIC,SAFETY CON TrolledStandard only Optional Accessories CA ASSY,CRTDISCRETE,ANODE LEAD,CRT,1,22 A10