Tektronix 7L13 Instruction Manual Download

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Summary of Contents for 7L13

Page 1: ...070 1673 00 TEKTRONIX 7L13 SPECTRUM ANALYZER INSTRUCTION MANUAL Tektronix Inc P O Box 500 Beaverton Oregon 97005 Serial Number First Printing APR 1974 ...

Page 2: ...sure you the fastest possible service Please include the instrument Type Number or Part Number and Serial Number with all requests for parts or service Specifications and price change privileges reserved Copyright c 1974 by Tektronix Inc Beaverton Oregon Printed in the United States of America All rights reserved Contents of this publication may not be reproduced in any form without permission of ...

Page 3: ... Preparation Check the 10 dB Div and LIN Mode Calibration Check the Frequency Readout Accuracy 3 2 Check the Range of the REF VAR Control the Range and Accuracy of the Gain Selector and the Gain Accuracy of the 10 dB Pushbutton Check the Operation of the Video Filters 3 3 Check Sensitivity Check Spurious Signals from Internal Sources Residual Responses 3 5 Check Resolution Bandwidth and Shape Fact...

Page 4: ... and 300 kHz Filter 4 12 Adjust the Resolution Gain Leveling Compensation 4 14 Adjust the Post Resolution Amplifier Gain 4 16 Minimize Intermodulation Products 50 MHz Calibrator Adjust the Calibrator Output CIRCUIT DESCRIPTION Block Diagram Description 5 1 Detailed Circuit Description 5 2 RF or Microwave Circuits Phase Lock and Frequency Stablization 5 3 YIG Driver Voltage Memory and Phase Lock Lo...

Page 5: ...Replacement Parts Repair and Exchange Program Soldering Technique Replacing Square Pins for Multi pin Connectors 6 6 Replacing Assemblies Front Panel Controls and Selectors Circuit Board Assemblies 6 8 DVM Logic and Readout Circuit Board Replacing the Sweep Circuit Board Replacing the IF Function Circuit Board 6 10 Replacing the Resolution Circuit Board Replacing Circuit Boards in the Honeycomb As...

Page 6: ...Fig 1 1 71 13 Spectrum Analyzer ...

Page 7: ...oltage data for troubleshooting orcircuit analysis are also provided adjacent to or on the diagram Section 10 Mechanical Parts List Exploded Drawings and Accessories Provides information necessary to order replaceable parts The Parts List is cross referenced to the Electrical Parts List Exploded drawing shows sequence of assembly and identifies assemblies Changes and Corrections Provides updating ...

Page 8: ...y f 5 MHz 20 of the Freq Span Div STABILITY after a 2 hour warmup period Within 2 kHz per hour at a fixed temperature when phase locked within 50 kHz when not phase locked INCIDENTAL FM see Fig 3 5 10 Hz peak to peak or less when phase locked and 10 kHz peak to peak or less for 5 seconds when out of phase locked mode VIDEO FILTERING Three selections of video filtering 10 Hz 300 Hz and 30 kHz are p...

Page 9: ...s the additional 10 dB of gain when the resolution bandwith is 30 Hz and the REFERENCE LEVEL is 100 dBm in the 2 dB DIV or LIN mode The REF VARiable control provides continuous gain adjustment between each calibrated REFERENCE LEVEL setting Provides 60 dB of attenuation in calibrated 10 dB steps Accuracy is 0 2 dB or 1 of the dB reading whichever is greater The maximum input power level to the RFA...

Page 10: ...dures including failure criteria etc can be obtained from Tektronix Inc Contract your local Tektronix Field Office or represen tative ACCESSORIES AND OPTIONS STANDARD ACCESSORIES 1 Spectrum Analyzer Graticule Clear plastic implo sion shield with LOG LIN REF and f frequency direction markings Tektronix Part No 337 1439 01 for 7403N oscilloscope and 337 1159 02 for other 7000 Series os cilloscopes a...

Page 11: ...plications Is contained In Tektronix Measurements Concepts Booklet Spectrum Analyzer Measurement Theory and Practice Part No 082 1334 00 A MARKER indicator lights when the FREQ SPAN DIV is at the MAXSPAN position and a notch on the baseline of the display indicates the center portion of the span that will be displayed when the FREQ SPAN DIV is reduced The center frequency or marker frequency is in...

Page 12: ...Operating Instructions 7L13 Fig 2 1 A Front panel controls and selectors ...

Page 13: ...Fig 2 28 Front panel controls and selectors Operating Instructions 7L13 2 3 ...

Page 14: ...ode Readings with the gain selector outside the blue tint sector are erroneous because the gain is electrically locked out the crt readout will display the symbol to signify that the reading is incorrect In the 2 dB DIV mode the full 70 dB range of the gain selector is usable Switching the gain fully cw with the RF Attenuator at 0 dB produces an accurate 100 dBm 2 4 reference level The dynamic ran...

Page 15: ... 0 5 volt of signal for external triggering In the SGL SWP mode the sweep is triggered by pushing the adjoining button This button lights during sweep time and serves as an indicator to determine camera shutter time when photographing slow scan time displays Minimum signal amplitude for triggering is 0 5 division of signal and 0 5 volt of external signal OPERATIONAL CHECK NOTE Operating Instructio...

Page 16: ...eep Span a Switch the FREQ SPAN DIV to MAXSPAN position b Position the 0 Hz response or LO feedthrough on the zero left graticule line with the HORIZ POSITION control c With the CAL OUT signal applied to the RF INput decrease the FREQ SPAN DIV to 50 MHz and tune the 5th marker 250 MHz to the center graticule line see Fig 2 3 d Calibrate the frequency span to 50 MHz DIV by adjusting the SWP CAL for...

Page 17: ...Light OUT RF Attenuator 0 dB CENTER FREQUENCY RESOLUTION Termination caps on CAL OUT Connect to Output Ports RF Input PULSE STRETCHER Out Sleeve pushed in so FREQ SPAN DIV and RESOLUTION are coupled together FREQ SPAN DIV 50 MHz Fig 2 2 Front panel selector positions and signal connections for initial operational check and front panel calibration ...

Page 18: ...peat these steps until the 2 dB DIV display is calibrated see Fig 2 4 then return the RF Attenuator to 0 dB REFERENCE LEVEL 30 dBm Ensure that the 30 dBm signal is 8 divisions in amplitude NOTE An alternate method of calibrating the display is to switch between the 10 d8 DIVand2 d8 DIVdisplay modes while adjusting the LOG CAL so the display amplitudes are equal then adjust the AMPL CAL so the disp...

Page 19: ...the signal source can cause reflections in the transmission line and degrade instrument performance Flatness sensitivity spurious response etc are all affected To reduce mismatch use good quality 50 f2 coaxial cable to connect the signal source to the RF INput and keep the cable as short as possible Cable losses become excessive above frequencies of 1 GHz Avoid applying high level signals above 30...

Page 20: ...and dBNV For 50 f2 systems dB uV dBm 107 dB Fig 2 6 Circuit of a 75 0 to 50 f matching pad ac coupled 2 Resolution Sensitivity and Frequency Span Resolution is the ability of a spectrum analyzer to discretely display adjacent signals within a frequency span This resolution ability is a function of analyzer 31 dBMV 5092 87 67 47 0 107 100 21 11 dBm dBmV 75 s2 75 s2 MINE NOME EMIMMOMME No MEMNON MEE...

Page 21: ...fect is caused by the 0 Hz response overdriving the list IF amplifier If you are operating between 0 Hz and 2 MHz do not set the Gain selector in this region The video filter is used for effective averaging of distributed signals such as noise and high frequency components on the display see Fig 2 8 When signals are closely spaced the filter may be useful in reducing modulation between the two sig...

Page 22: ... photographing displays at slow sweep rates The ac tivating button does not arm the trigger circuit like some time base units When triggering on pulsed spectra it may be necessary to fine tune the sweep start away from a null point to trigger the display 2 1 2 7 Manual Scan of the Spectrum This position is used to examine a particular point or portion of the display such as one of the null points ...

Page 23: ...de b Note the frequency readout e g 1002 MHz c Apply the CAL OUTsignal to the RF INput and tune the nearest 50 MHz marker to the graticule centerline Operating Instructions 71 13 d Set the frequency readout with the CALadjustment to read the exact frequency e g 1000 MHz e Retune to the unknown signal approaching it from the low side and note the frequency readout Measuring Absolute Signal Levels S...

Page 24: ... amplitude of the other signals as a percentage of this reference Using the Analyzer Below 100 kHz The sensitivity of the analyzer degrades about 0 3 dB kHz below 100 kHz for example the sensitivity is about 113 dBm at 50 kHz with 30 Hz resolution Reference level operation becomes limited to 50 dBm as the center frequency approaches 1 kHz because of the LO energy that exists in the 1st IF pass ban...

Page 25: ...nary Front Panel Setup Procedure described in the Operating Instructions and calibrate the 71 13 sweep to the oscilloscope deflection sensitivity Adjust the contrast ratio between the clipped subdued baseline and the remaining display Section 3 71 13 The 1st and 2nd LO OUTports must be terminated into 50 f2 at all times For optimum performance keep the termination caps in place when these ports ar...

Page 26: ...acy when the signal is centered on the screen should be within f 5 MHz 20 of the FREQ SPAN DIV orwithin f5 MHz with a frequency span of 1 MHz DIV 3 2 4 Check the Range of the REF VAR control the Range of the Gain Selector and Gain Accuracy of the 10 dB GAIN pushbutton Accuracy within f1 dB 10 dB step Variable range 10 dB a Switch the display mode to 10 dB DIV FREQ SPAN DIV to 0 5 MHz and the RESOL...

Page 27: ... of the VIDEO FILTERS The VIDEO FILTERS reduce or average the noise level on the display See Fig 3 1 Tune to one of the Calibrator signals and check the operation of the filters with RESOLUTION settings of 3 MHz and 3 kHz 6 Check Sensitivity 128 dBrn to 80 dBm depending on the resolution bandwidth NOTE Sensitivity is measured in the LIN mode and is based on a signal amplitude that equals two times...

Page 28: ...om graticule line then switch the display mode to 10 dB DIV h Switch the RF Attenuator to 0 dB and increase the Gain selector setting for a REFERENCE LEVEL readout of 60 dBm Gain selector must be in the blue sector i Reduce the FREQ SPAN DIV to 1 MHz and the RESOLUTION bandwidth to 3 MHz Note the average noise level below 60 dBm Sensitivity for a resolution bandwidth of 0 3 MHz must equal or excee...

Page 29: ...pur is marginal within 3 dB of specifications and you desire to check its amplitude more accurately proceed as follows O 1 Decrease the FREQ SPAN DIV to 50 kHz or less and the RESOLUTION bandwidth to 3 kHz This will decrease the noise with respect to the signal amplitude Keep the signal centered on screen with the TUNING control as the FREQ SPAN is decreased Performance Check 71 13 2 Decrease the ...

Page 30: ...z and change the display mode to 2 dB DIV Check the bandwidth at the 6 dB half screen level Bandwidth must equal 30 Hz 6 Hz o Switch the display mode to 10 dB DIV and measure the shape factor Shape factor for 30 Hz resolution must equal 12 1 or better see Fig 3 3C 9 Check Incidental Wing 10 Hz for any inter nal sweep rate when phase locked 20 kHz without phase lock NOTE A storage mainframe is desi...

Page 31: ...emaining characteristics continue to the next part of this section Introduction History Information Performance Check 71_13 Y e e Fig 3 5 Illustration to show how Wing is measured with a resolution bandwidth of 30 Hz PERFORMANCE CHECKS THAT REQUIRE TEST EQUIPMENT The following procedures check the accuracy of the 71 13 calibrator and RF Attenuator the display flatness intermodulation distortion vi...

Page 32: ...rk Generator Marker outputs 1 s to 1 is Tektronix 2901 with Harmonic Modulator Part No 067 0640 00 Accuracy 0 001 Used to check TIME DIV and FRED SPAN DIV accuracies Pulse Generator Pulse period 40 ps Tektronix 2101 Pulse Gen erator Used to check Pulse duration 0 2 ps PULSE STRETCHER Pulse amplutude 0 5 V P P Digital Counter To 50 MHz Tektronix 7D14 Digital Counter with a readout 7000 Series Oscil...

Page 33: ...rement is not possible a Vector Voltmeter Method Hewlett Packard Model 8405A Vector Voltmeter 1 Terminate the A probe with a BNC 50 0 feedthrough termination and connect the probe through the termination to the CAL OUTconnector on the 71 13 3 9 EQUIPMENT OR TEST CHARACTERISTICS TYPE OR MODEL FIXTURE REQUIRED RECOMMENDED VHF 10 MHz to 480 MHz Hewlett Packard Model 608D or 608E UHF 450 MHz to 1230 M...

Page 34: ... not exceed 110 3 dB 0 75 minor divisions with a 2 dB DIV display mode 5 If necessary adjust the output of the calibrator as described in the Vector Voltmeter method for 30 dBm 3 Check RF Attenuator Accuracy Within f0 2 dB 1 of the dB readout whichever is greater NOTE The RF Attenuator accuracy is checked at the factory to ensure that it is within specifications This check will detect any componen...

Page 35: ...tch the 300 Hz VIDEO FILTER on and the display mode to 10 dB DIV Decrease the sweep speed until the UNCAL indicator light goes out b Apply two signals that are separated approximately 2 MHz from the output of two 50Q signal sources through 10X attenuators for isolation then through a BNC T connector to the RF INput of the 71_13 Fig 3 7 illustrates this setup c Adjust the output of both generators ...

Page 36: ... kHz to 100 kHz using the above procedures IM products must not exceed 50 dB below the reference signals 6 Check PULSE STRETCHER Operation Pulse Stretcher should increase pulse falltime to at least 2 5 ps per vertical division 3 1 2 Since the pulse stretcher responds only to pulsed spectra a pulse generator is used to make this check Use extreme care to ensure that the pulse amplitude into the RF ...

Page 37: ...heck Triggering Operation and Sensitivity a Apply a 100 MHz signal from the VHF signal generator to the RF Input of the 71 13 and tune the CENTER FREQUENCY to the signal b Apply a 10 kHz signal from the sine wave signal generator through a T connector BNC to BNC cable and BNC to pin jack cable to both the EXT IN HORIZ TRIG jacks on the 71 13 and the External Modula tion Input of the VHF signal gen...

Page 38: ... triggering operation 7000 Series Oscilloscope with 71 13 Spectrum Analyzer m Return the TRIGGERING SOURCE to FREE RUN and the MODE to NORM 8 Check the External Horizontal Input Voltage Requirement 0 V to 10 V 1 V should sweep the analyzer the full span a Switch the oscilloscope mainframe Vert Mode switch off the vertical signal right for 3 hole mainframes and the 71 13 TIME DIV to EXT b With no s...

Page 39: ...pply the marker and trigger output from the time mark generator through the Harmonic Modulator to the RF Input of the 71 13 Set the 71 13 selectors and controls as follows FREQUENCY 800 MHz Display Mode 10 dB DIV RF Attenuator O dB REFERENCE LEVEL 30 dBm PHASE LOCKED Mode ON FREQ SPAN DIV 100 MHz RESOLUTION 3 MHz Uncoupled b Check frequency span accuracy and linearity as per Table 3 2 NOTE At some...

Page 40: ...lector and reduce the span to 0 leaving the RESOLUTION at 3 MHz Switch the display mode to 2 dB DIV d Switch the TRIGGERING to INT SOURCE and NORM MODE and the TIME DIV to 1 ms Adjust the VHF signal generator output for a display amplitude of approximately 2 divisions see Fig 3 11 ccacT _ Marker Ou Fig 3 10 Test equipment setup to check TIME DIV accuracy Fig 3 11 Display showing time markers for c...

Page 41: ...he error between each marker and its respective graticule line Performance Check 71 13 f Disconnect the signal to the RF INput and return the 71 13 to normal spectrum operation This completes the performance check for the 71 13 It will now perform within the specifications described in Section 1 ...

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Page 43: ...s in the calibration procedure History information that is applicable to earlier instruments is included either as a deviation within a step or as a subpart to a step Interaction Adjustments that interact with other circuits are noted and reference is made to the affected circuit which may require re adjustment Equipment Required Equipment for calibration includes the equipment listed for the Perf...

Page 44: ...e it will plug into the interface connector The guide pin is removed by pulling it out with a pair of pliers 3 Turn the power ON and allowthe instrument circuits to stabilize before making any adjustments approximate ly 20 minutes Calibration Procedure 71 13 FREQ SPAN AND 1ST LO CALIBRATION 5 Adjust the Frequency Span of the 1st LO and 16 19 MHz Oscillator Page 4 8 6 Calibrate the Center Frequency...

Page 45: ...ngth of the 71 13 to 10 divisions with the front panel SWP CAL then center the trace within the graticule area Apply the CAL OUT signal to the RF INput and switch the display mode to 10 dB DIV e Change the FREG SPAN DIV to 10 MHz and tune the center frequency to one of the calibrator markers Calibration Procedure 71 13 f Decrease the FREQ SPAN DIV to 1 MHz keeping the marker centered with the CENT...

Page 46: ...e extender plug from the right vertical compartment of the 71 13 mainframe oscilloscope and install a vertical amplifier unit e g 7A16 7A18 I Switch the mainframe trigger Source to Vert Mode and apply the 40 mV Calibrator signal to the amplifier input Set the Volts Div to 1 V m Switch the 71 13 TRIGGERING SOURCE to INT and adjust the LEVEL control for a triggered display 4 4 Fig 4 2 Location of ad...

Page 47: ...through termination to the Input of the vertical amplifier unit Set the VoltslDiv to 5 V r Adjust the 71 13 TRIGGERING LEVEL control for a triggered display Calibration Procedure 71 13 s Adjust the Time Div Cal R1190 Fig 4 2 for 1 marker division t Check the timing accuracy for each TIME DIV selection Timing accuracy must be within 5 u Change the TIME DIV to 50 is and apply 50 ps markers from the ...

Page 48: ... ccw 3 Adjust the Gain Compensation and Calibrate the REF VAR CAL Reference Level Display Mode LIN TIME DIV 20 ms a Switch the display mode to 2 dB DIV and position Triggering the baseline of the display on the bottom graticule line if MODE NORM necessary SOURCE FREE RUN FREQ SPAN DIV 50 MHz b Apply a 10 MHz signal at 10 dBm from a RESOLUTION 3 MHz calibrated signal source through appropriate adap...

Page 49: ... dB DIV R703 Fig 4 4 Calibration Procedure 71 13 k Increase the signal level to 0 dBm then adjust the 10 dB Ref Linearity R542 Fig 4 4 so the trace is at the graticule line I Decrease signal level in 10 dB steps checking the display calibration for the 10 dB DIV mode Trace should shift down 1 f0 1 division per each 10 dB step to a maximum of 1 5 dB overthe 70 dB dynamic range Repeat steps h throug...

Page 50: ...t in step 1 Fig 4 6 Location of P69 and R51 on Hybrid Assembly A50 a Set the front panel selectors as follows FREQ SPAN DIV 100 MHz RESOLUTION Uncoupled 3 MHz TIME DIV 10 ms CENTER FREQUENCY 500 MHz Display Mode 10 dB DIV REFERENCE LEVEL Minimum sensitivity then increase for full screen display VIDEO FILTER 30 kHz SWP CAL 10 division trace b Apply the marker and Trigger output of the time mark gen...

Page 51: ...MENEEMEM SENNE 3od Fig 4 8 100 MHz markers on a 100 MHz DIV frequency span Fig 4 7 Location of the YIG Driver and Voltage Memory adjustments Calibration Procedure 7L13 g Decrease the FREQ SPAN DIV to 50 kHz RESOLUTION bandwidth to 3 kHz and the TIME DIV to 20 ms Apply 10 us trigger signals and 10 ns markers to the Input h Adjust the 16 19 MHz sweep gain with R1960 Fig 4 9 for 1 marker 2 divisons F...

Page 52: ...ENTER FREQUENCY to center the 900 MHz marker on screen as the FREQ SPAN DIV is decreased to 1 MHz The 900 MHz marker is the 9th marker to the right of the 0 Hz marker d Adjust the DVM offset with R2135 Fig 4 10 so the LED readout is 900 MHz e Return the FREQ SPAN DIV to 100 MHz and tune the CENTER FREQUENCY to the 100 MHz marker Reduce the FREQ SPAN DIV to 1 MHz so the 100 MHz signal can be accura...

Page 53: ...the phase lock off and tune the signal two divisions to the left of center f Switch the phase lock on and off and check that the signal locks remain near the same point g Remove the shorting strap across S2608 Switch the AUTO PHASE LOCKED switch on and center the signal on screen 8 Adjust the Error Amplifier Gain a With the signal centered decrease the FREQ SPAN DIV and RESOLUTION to 200 Hz 30 Hz ...

Page 54: ...er bandpass with C82 the 3 MHz helical resonator Fig 4 13 and C456 in the filter circuit Fig 4 14 so the response is similar to that illustrated in Fig 4 16 NOTE Keep the signal centered as the tuning adjustments are made Switch back to 30 kHz or 3 kHz RESOLUTION periodically to ensure that the signal is tuned to the graticule center This locates the center of the 10 MHz IF There is no recommended...

Page 55: ... pin 1 of J303 f Change the RESOLUTION to 3 MHz Adjust the narrow filter circuits with C472 and C475 Fig 4 16A for a flat topped response that is similar to that illustrated in Fig 4 16B Keep the response centered as these ad justments are made Do not change the front panel tuning control setting or the frequency of the signal generator Bandpass at the 6 dB down point should range between 500 kHz ...

Page 56: ... the gain for each RESOLUTION set ting with the amplitude adjustments listed in Table 4 1 and illustrated in Fig 4 18 so the signal amplitude remains constant through all resolution settings NOTE Decrease the sweep speed to maximize the signal amplitude for the 300 Hz RESOLUTION setting TABLE 4 1 e Change the FREQ SPAN DIV to 1 MHz RESOLUTION to 3 MHz RF Attenuator to 0 dB and turn the Gain select...

Page 57: ...1111 m or ihrW 11111 i l dB GAIN 82730 J Hz AMPL B Gain compensation adjustments on the YIG driver 30 Hz filter circuit boar Fig 4 18 Resolution gain compensating adjustments Calibration Procedure 7L13 4 15 ...

Page 58: ...amplifier so an input of 17 dBm will provide full screen deflection a Switch the FREQ SPAN DIV to 1 MHz 100 kHz and the RESOLUTION to 3 MHz 300 kHz Set the TIME DIV to 10 ms Switch the REF VARiable to CAL Switch the display mode to 2 dB DIV and position the trace at the bottom graticule line b Apply a 10 MHz signal at 17 dBm from the signal generator through a BNCto subminiature SEALECTRO adapter ...

Page 59: ...pe left side panel to gain access to the 71 13 calibrator Adjust 3 Check that the RMS reading is between 6 85 mV R956 Fig 4 21 for an output level of 30 dBm 7 07 mV and 7 3 mV 30 dBm is 7 07 mV RMS into 50 i2 RMS C95 Adjust for minimum 3rd order inter modulation products Fig 4 19 Equipment setup to measure IM distortion Calibration Procedure 71 13 Fig 4 20 Location of C95 in 3rd Mixer Assembly Fig...

Page 60: ... that were recommended for the preceding method can be used to verify the signal source output level 1 Set the FREQ SPAN DIV to 5 MHz and the RESOLUTION to 3 MHz Switch the RF attenuator to 10 dB and the Gain selector fully ccw Push in the 2 dB DIV LOG display button 2 Apply a calibrated 30 dBm 50 MHz signal to the RF INput of the 71 13 and tune the frequency to center the signal in the graticule ...

Page 61: ...st mixer 1st IF is centered at 2 095 GHz A bandpass filter 10 MHz wide with a center frequency of 1 095 GHz attenuates the upper sideband and a 2 2 GHz low pass filter ensures the outband integri ty of the bandpass filter The 1st IF is converted to 105 MHz 2nd IF in the 2nd mixer by mixing the 2nd LO frequency of 2 2 GHz with the 1st IF of 2 095 GHz The 2nd IF signal is amplified by a Pre Resoluti...

Page 62: ...begins at 2 095 GHz Signals in the frequency band from 0 to 1 8 GHz then pass through a 3 dB isolation pad to the 1st mixer 5 2 The 1st mixer a double balanced type converts the incoming broad spectrum of signals to a 2 095 GHz IF by mixing these incoming signal frequencies with the output of the 1st LO Al 2 The 1st LO may be swept and tuned within the 2 095 GHz to 3 895 GHz band The output of the...

Page 63: ...cked by a translation phase lock system which is described below The 1st LO phase lock loop contains a reference oscillator a pulse generator and sampler a phase detec tor an error amplifier and a compensating amplifier that drives thefrequency determining element of the oscillator A narrow rectangular pulse from the sampler driver at one half the reference oscillator period and the output of the ...

Page 64: ... U1715 Q1715 on A1400A5 The amplifier output drives the collector of the 2 2 GHz oscillator to control its frequency 5 4 The sampling generator and driver A1400A6 are part of the 1st LO phase lock loop The output from a 2 1944 MHz crystal controlled oscillator is applied through Q1820 and Q1825 to a divide by two counter U1825 The 1 0972 MHz output from the counter triggers avalanche diode CR1832 ...

Page 65: ...coil driver for frequency spans of 2 MHz div to 0 1 MHz div The tune control voltage is still applied to the main coil driver 3 The sweep and tune control voltages are removed from Circuit Description 71 13 the YIG oscillator driver circuits and applied to the 2nd LO driver for frequency spans of 50 kHz div or less The 1st LO is phase locked providing the front panel PHASE LOCK switch is on Tuning...

Page 66: ... output load for Q85 is a three sectional helical resonator that is tuned so the bandwidth is reduced to 3 MHz The 3rd mixer converts the 105 MHz IF to 10 MHz IF by mixing 105 MHz with the output of a crystal controlled 95 MHz oscillator Aperature coupling is used between each section of the helical resonator The 3rd mixer is a blanced mixer 1 85 and C95 are tuned to the sum of the two input frequ...

Page 67: ...t supply is set by R2583 and R2584 at the non inverting input to U2585 U2585 drives the output transistor 02580 30 Hz Filter 18 Circuit Description 71 13 This filter contains an amplifier crystal filter and a 10 dB gain boost circuit The 10 MHz IF is routed through the filter when K354 is de energized and K2710 is energized 02710 and 02715 are emitter coupled amplifiers Gain of the amplifier is se...

Page 68: ...ion of the IF signal feedback current is supplied through CR772 and CR771 This produces a circulating current through the diodes proportional to the average signal input level The negative video output signal is developed across R772 R819 and R771 The video is then applied through a filter network to the vertical output stages Linear Baseline Offset adjustment R803 compensates for baseline shift w...

Page 69: ... CLOCK 0 20 000 COUNTER MEN LATCH ONE DRIVERS MEN LED s CF IS FROM TUNE POTENTIOMETER INTEGRATOR Fig 5 3 Functional block da 9 of the Frequency Readout circuit Circuit Description 71 13 state is high 02320 is switched on and positive current through the interface pin A17 High reduces or clips the crt beam intensity The amount of current through 02320 or 02330 is a function of the Baseline Clipper ...

Page 70: ...ode VR2115 sets this output at a very 5 10 stable 11 7 volts This source provides the reference for the offset current through R2135 and the reference forthe negative input of the comparator 02145 As the positive going ramp from U2110 crosses the reference voltage the output of the comparator steps high This triggers the multivibrator U2030A U2030B and the voltage at pin F goes high to turn diodes...

Page 71: ...Uncal circuit Circuit Description 7L13 The multiplication and division of quantities in this equation can be done by summing the logarithm of the various parameters The equation becomes log freq span log 0 5 log min B V log t 1 The logarithmic summation of these parameters is performed by an analog circuit and compared against ground or zero The resultant indicates if the display is uncalibrated o...

Page 72: ...ht DS1152 is supplied by transistor 01150 During gate time in the SGL SWP mode the lamp drive from U1180 goes low This gates a low out of U1 160B to turn transistor 01150 on In the SGL SWP mode pin 6 of U1180 is grounded so the gate generator will not run until it has been reset by pushing the Start button and gating a signal through the NAND gate U1160C to trigger 01120 This pulls pin 7 of U1180 ...

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