Motorola D102O Instructions d'exploitation

TM 9-6625-2467-15DEPARTMENT OF THE ARMY TECHNICAL MANUALOPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT,AND DEPOT MAINTENANCE MANUAL(INCLU

Fig. 2-2. Handle positioned to provide a stand for the instrument.CAUTIONThe Type 491 should not be operated with thesevoltage selector switches in im

Type 491INTENSITYFOCUS and ASTIGMATISMSCALE ILLUMPOSITION (Horizontaland Vertical)TIME/DIVVARIABLETRIGGERSLOPELEVELSOURCEDISPERSION RANGEDISPERSION-CO

Test OscilloscopeTime/Cm 1 mSVolts/Cm .2Input CouplingDCTriggerAdjusted for free runningsweep7. Adjust Vertical Amplifier Gainoa. Test equipment setup

INTENSITYFOCUS and ASTIGMATISMINTENSIFIERSCALE ILLUMPOSITION (Horizontaland Vertical)Fig. 6-11. Equipment setup for adjusting and checking triggering,

Fig. 6-12. Adjustments for trigger circuit on the horizontal displaycircuit board assembly.10. Check External Triggeringa. Equipment setup is given in

Fig. 6-13. Setup to check LINE triggering operation.11. Check line TriggeringCAUTIONUse special care to avoid shorting the transformerterminal to grou

Fig. 6-14. Equipment setup to check and adjust sweep circuits, Steps 12 through 20.Type 491INTENSITYFOCUS and ASTIGMATISMINTENSIFIERSCALE ILLUMPOSITIO

Fig. 6-15. Location of trigger and sweep adjustments.c. Preset the Sweep Cal R787 to midrange. Adjust theSweep Gain R813 (see Fig. 6-15) for 10.5 divi

c. Check—The amplitude of the SAW OUT signal, shouldmeasure between 70 and 90 mV.17. Check Unblinking Waveformo. Equipment setup is given in step 16.b

Fig. 6-19. Test equipment setup to adjust and check dispersion accuracy.Type 491INTENSITYFOCUS and ASTIGMATISMINTENSIFIERSCALE ILLUMPOSITION (Horizont

calibrate the dispersion to specifications, the fol-lowing techniques may be tried.Shift the sweep oscillator RF output voltage to anew level. (The ou

Center frequency (radio frequency or intermediate fre-quency)-That frequency which corresponds to the centerof the reference coordinate.Center frequen

Fig. 6-22. Dispersion calibration adjustments.d. Adjust the DISPERSION CAL R208 (Fig. 6-22) for 1marker/division over the center 8 graticule divisions

INTENSITYFOCUS and ASTIGMATISMINTENSIFIERSCALE ILLUMPOSITION (Horizontal andVertical)TIME/DIVVARIABLETRIGGERSLOPELEVELSOURCEDISPERSION RANGEDISPERSION

Fig. 6-24. Location of narrow band IF amplifier adjustments.Fig. 6-26. Display pattern when resolution is correctly adjusted.Fig. 6-25. Typical test o

Fig. 6-27. Location of C504 and C508.d. Adjust L444 (wide band amplifier), T464, T454, C435 andC425 (Fig. 6-24) in the order listed for optimum signal

Fig. 6-29. Test equipment setup to adjust and check kHz/DIV dispersion accuracy.Type 491INTENSITYFOCUS and ASTIGMATISMSCALE ILLUMPOSITION (Horizontal

Fig. 6-30. Adjustments for the kHz/DIV discriminator.b, Apply 10 ns and 1 µs markers from the Time-MarkGenerator through the 20 dB attenuator to the b

Fig. 6-31. Typical displays when checking or adjusting kHz/DIVd. Center the IF CENTER FREQ controls and change theDISPERSION to 50 kHz/div.e. Apply 10

Fig. 4-32. Test equipment setup to check or adjust the phase lock circuit.Type 491INTENSITYFOCUS AND ASTIGMATISMSCALE ILLUMPOSITION (Horizontal andVer

Fig. 6-33. Adjusting avalanche voltage.just below the state of free running avalanche. Free runningavalanche, appears as an RF burst signal between th

f. Adjust L1104 (Fig. 6-34) until the oscillator shift range,as the INT REF FREQ is rotated, is 1.2 kHz. The display isthe 200th harmonic of the 1 MHz

plays on the CRT that are not tunable with the RF center fre-quency controls.2. Image response-The superheterodyne process resultsin two major IF resp

Fig. 6-35. Test equipment setup to check dynamic range, IF GAIN control range, IF ATTENUATOR dB accuracy RECORDER signal out ampli-tude and incidental

29.a.b.withCheck Dynamic Range of Vertical DisplayModesEquipment setup is shown in Fig. 6-35.Apply a 200 MHz signal from an RF Signal Generatora calib

Fig. 6-36. Typical Video Filter integrated display of 200 MHz RFdivision signal amplitude on the Type 491. Note the dBmreading of the Signal Generator

35. Check Incidental Frequency ModulationNOTESignal source must supply a very stable 200 MHzsignal to accurately measure incidental FM andthe Type 491

Fig. 6-38. Equipment setup to adjust wide band IF amplifier and check flatness.Type 491 FINE RF CENTER FREQCenteredINTENSITYFOCUS and ASTIGMATISMSCALE

Fig. 6-39. Wide band IF and Mixer tuning adjustments.bration. These filters require special test equip-ment and technique to calibrate. Contact yourlo

1) Set the front panel controls as follows:RF CENTER FREQUENCY10 MHzDISPERSION RANGEMHz/DIVDISPERSION5 MHz/divIF ATTENUATOR20 dBVERTICAL DISPLAYLINTIM

Fig. 6-40. Equipment setup to check internal spurious responses.Type 491DISPERSION RANGEINTENSITYDisplay of nominal bright-DISPERSIONnessFOCUS & A

37.a.b.Fig. 6-41. Typical equipment setup to check response flatness, sensitivity, frequency calibration and phase lock operation.Adjust Band A Mixer

Fig. 6-42. Typical equipment setup to check response flatness, sensitivity, frequency calibration and phase lock operation for band C.A secondary or a

Fig. 2-4. Front panel controls and connectors.FINE-A one turn control that operates in conjunction withthe IF control to provide a fine adjustment of

Fig. 6-43. Typical equipment setup to check response flatness, sensitivity, frequency calibration and phase lock operation for band C, scales 7through

TABLE 6-9Suggested FrequencyBandSensitivitySignal Generator(Equal to or better than)Dial Accuracy(Refer to equipment list)100 kHz1 kHzCheck FrequencyH

Fig. 6- 45. Alternate equipment setup that will check dial accuracy, mixer and oscillator operation, and LO phase lock effectiveness.38B. Alternate Pr

tune the RF CENTER FREQ to any harmonic signal. Depressthe LOCK CHECK button and adjust the FINE RF CENTERFREQ control to establish a lock mode on the

1. Perform the necessary repairs. Replace all covers. Alld. Tighten the set screws.screws must be tight.7. Check the dial tape tracking on band B at s

Fig. 6-49. Local oscillator assembly showingvolts at the varactor biers terminal for the band B oscillator.See Fig. 6-48.4. Use an accurate frequency

Fig. 6-49. Band C Assembly Alignment Diagram.3. Turn the POWER switch to OFF. Loosen the inductor10. Set the frequency meter to 835 MHz and tune the l

calibration. See Maintenance Section. The probe assembliescan be oriented within the magnetic field of the oscillatorchamber by loosening set screws a

PARTS LIST ABBREVIATIONSBHBBHScap.cercompcormCRTcskDEdiadivelect.EMCEMTextF&IFHBFHSFil HBFil HShhex.HHBHHSHSBHSSIDincdbinding head brassbinding he

1 MHz MARKERS OUT-EXT REF FREQ IN-A BNC con-nector that provides 1 MHz marker output signals to cali-brate the dispersion.With the INT REF FREQ contro

SPECIAL NOTES AND SYMBOLS× 000Part first added at this serial number00 ×Part removed after this serial number*000-0000-00Asterisk preceding Tektronix

SECTION 7ELECTRICAL PARTS LISTValues are fixed unless marked Variable.TektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionBulbsB901150-0045-00I

Cl 28cl 30Cl 32C133Capacitors (contjTektronixSerial/Model No.Ckt. No.Part No.Eff -DiscDescription100V5=)”500 v570500 vCl 36cl 37Cl 38cl 39cl 40C143cl

Capacitors (corrtjTektronixSerial/Model No.Ckt. No.Part No. EffDiscDescriptionC365C367C368C373C376C383C384C385C386C401C412C413C416C422C423C424C425

Capacitors (contjTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionC525C527C530C534C537C539C600C601C602C603C604C605C606C607C609C61 OC611C612

Capdta9 (cent)TdrtronixSoriaVModei No.Ckt, No.Part No. EffDisc DescriptionC741053C755C761c705AC7858C785CC78SDC785EIc904A#8,cC906C910C913C913C922C9240

cl 020cl 021Cl 025cl 032cl 033Capacitors (cent)TektronixSerial/Model No.Ckt. No.Part No. EffDiscDescription+80~o—20%+807!0 –20%0.03 pF0.01 pF0.001

DiodesTektronixSerial/Model No.Ckt. No,Part No.EffDiscDescription0737D82084D860203D224D252D252D2700272D2770279D314033403610362D365D373D376D383D386ID41

Diodee (ContjTektronixSerial/Model No.Ckt. No.Part No. EffDiscDescriptionD742Tek SpecD744Tek SDOC● 152.oo75~*1 52-0075-00*1 52-0185-00*1 52-0185-0

TektronixSerial/Model No.Ckt. No.Port No. EffDiscDescription159-0025-00F902159-0022-00F1 0081594022-000.5 A 3AG Fast-Blo1 A 3AG Fast-Blo1 A 3AG Fa

12. Tune the signal to the extreme left graticule line withthe RF CENTER FREQUENCY control. Note the dial reading.Tune the signal to the extreme right

Connectors (corst)TektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionJ151CoaxialJ188CoaxialJ363J370J373J376J379J401J470J501J650J700J790J1120J1

Inductors (contjTektronixSeriul/Model No.Ckt. No.Part No.Eff -DiscDescriptionL124L124L134L144L147L151LI 88L222L313L314’L320L325L333L343L348L35Bl%M44L4

TransistorsTektronixSerial/Model No.Ckt. No.Part No.Eff -Disc DescriptionQ542N3415Q64Q120Q120Q130Q130Q140Q200Q220Q230Q240Q260Q270Q280Q290Q31OQ320Q3

Traneietom (cent)TektronixSerial/Model No.Ckt. No.Part No. EffDiscDescriptionQ760Q761*] 51.019.2.00● 151 -0192-00151-0188-00151-0188-00*151 .0192-005i

Resistore (contJTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionR14R14315-0470-00317-0151-00315-0330-00317-0151-00315-0200-00317-0200-00315

Resistors (contjTektronixSerial/Model No.Ckt. No. Part No.EffDiscDescriptionR183R184RI 85R200R201R203R204R206R208R209R21OAR21 OBR21 OCR21ODR21 OER

Resistors (cent)TektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionR263Prec1 y.R264Prec1%R266321-0143-00321-0423-00321-0135-00321-0135-003

Redstore (contjTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionR464R466R501R502R514R516R517R524R525R530R531R532R534R537R539R540R541R543

Resistors (corst)Tektronix Serial/Model No.Ckt. No.Part No.Eff “DiscDescriptionR646Ww1%R6505 “/0R651R653Q655308-0413-00315-0683-00315-0273-00315-0102-

Resistors (cot-it)TektronixSerial/Model No.Ckt. No.Part No. EffDiscDescriptionR720R721R722R724R725R725R730R732R733R735R736R737R739R741R?43R744R745R

3. Adjust the FOCUS control forvertical sections of the display.4. Repeat the two adjustments fordisplay definition.Trace Alignmentoptimum focus of th

Resistors (contjTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionR7895%R790R791R793R794315-0101-00315-0623-00315-0621-00315-0101-00315-0101

Raiders (Conf)TektronixSerial/Model No.Ckt. No.Part No. EffDiscDescriptionR954R956R958R960!!962R964R966R967R96BR969R974R976R984R990R1OOOR1 001R1OO

Resistors (contjTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionR1 053R1 055RI 057R1 059RI 062R1 063RI 065R1 068R1 070R1 071R1 073R1 0

Resistors (conf)Tektronix Serial/Model No.Ckt. No.Part No.EffDiscDescriptionRI 136iv137R1 13t?R1140R1 141R1142R1143R1144RI 145R1147R1148R1 149R1 1

Reeistors (corrtjTektronix Serial/Madel No.Ckt. No.Part No. EffDiscDescriptionRI 197315-0124-00120 kCty4 w5%RI 198315-0302-003 k~y4 w5%R1199315-02

TransformersTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionn4*1 20.-T120&l ~@28.~T3311347T354T424T4341454T464T640T900T101OT1128T11

Cable Assemblies (contjTektronixSerial/Model No.Ckt. No.Part No.EffDiscDescriptionW150*1 75-0313-0041/d inchW200*175-0358-00213/ld inchW300*1 75-0358

FIGURE AND INDEX NUMBERSItems in this section are referenced by figure and index numbers to the illustrationswhich appear on the pullout pages immedia

INDEX OR MECHANICAL PARTS LIST ILLUSTRATIONS(Located behind diagrams)FIG. 1 FRONTFIG. 2 REARFIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIESFIG. 4 POWER

Figure -6SECTION 8MECHANICAL PARTS LISTFIG. 1 FRONTFig. &QIndex TektronixSerial/Model No.No.Part No.EffDisc ~Description123451-1-2-3-4-5-7-8-

Fig. 2-7. Changing band C Coaxial Mixer to Wave Guide Adapter,The Mixer Adapter or Coaxial Mixer may be removed fromthe input receptacle by turning th

FIG. 1 FRONT (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDescriptionDiscY123451-22 366-0215-02KNOB. charcoal lever—TRIGGER [SOURCE

FIG. 1 FRONT (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No. EHDescriptionDiscY123451-44199-0066-00ili-ioio:&11ATTENUATOR, padmoun

FIG. 1 FRONT (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDiscDescriptionY123451-71 376-0068-00COUPLING. . . . . -213-0048-00-72

FIG. 2 REARFig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDiscDescriptionY123452-98 175-0415-00 BO101 00175-0312-00 B09041 O-99 175-0417

FIG. 2 REAR (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDiscDescriptionY123452-20 407-0272-00---- . .-21 211-0512-00-22 210-04574

FIG. 2 REAR (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDiscDescriptionY123452-47 179-1097-00 BO101 00179-1194-00 B020000179-

FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIESFig. &Index TektronixNo.Part No.3-610-0175-00-- ilo-ol;3:oo. . . . . --1260-0642-00-2337-0799-00

FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No,EHDiscDescriptionY123453-26 136-0217-00.

FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tNo.DescriptionPart No.EffDiscY123453-54 210-0259-00

FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDiscDescriptionY123453-75-76-77-78-79-

Mixer PeakingAs the analyzer sweep rate is increased, the amplitudeof the CW signal will decrease and the bandwidth becomeswider; which signifies that

FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIES (cont)Fig. &QIndex Tektronix Serial/Model No.tNo.Part No.EffDiscDescriptionY12345SHIELDmounting h

FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.EffDiscDescriptionY123453-123 337-0805-00-

FIG. 4 POWER CHASSISFig. &QIndex TektronixSerial/Model No.tNo.Part No. EffDiscDescriptionY123454-1 -------2 ;12-0522:00-3 210-0812-00-4 354-0019-0

FIG. 4 POWER CHASSIS (cont)Fig. &QIndex Tektronix Serial/Model No.tNo.Part No.EffDiscDescriptionY12345TRANSISTORmounting hardware: (not included

FIG. 4 POWER CHASSIS (cont)Fig. &QIndex Tektronix Serial/Model No.tNo.Part No.DescriptionEffDiscY123454-57-58-59-60-61-62-63-64-65358-0215-0067

FIG. 5 TiME/DIV SWITCH & OSCILLATOR ASSEMBLIESFig. &QIndex TektronixSerial/Model No.tNo.Part No, EffDiscDescriptionY123455-1262-0787-001. .

FIG. 5 TIME/DIV SWITCH & OSCILLATOR ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tNo.Part No.DescriptionEffDiscY123455-27 179-109

FIG. 5 TIME/DIV SWITCH & OSCILLATOR ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tDescriptionNo.Part No.EffDiscY123455-42 384-0423-

FIG. 5 TIME/DIV SWITCH & OSCILLATOR ASSEMBLIES (cont)Fig. &QIndex TektronixSerial/Model No.tNo. Part No.EffDiscDescriptionY123455-64 407-029

Figure -1 Figure -2FIG. 6 CRT SHIELD ASSEMBLYFig. &Qindex TektronixSerial/Model No. tNo.Part No.EffDiscDescriptionY123456-626-0440-00----- .33

Fig. 2-9. Frequency spectrum of a pulsed cw signal.b. Tune for minimum signal shift as the DISPERSIONRANGE is switched from MHz/DIV to kHz/DIV positio

FIG. 7 CABINET ASSEMBLY AND HANDLEFig. &QIndex Tektronix Serial/Model No.tNo.Part No.EffDiscYDescription123457-1-2-3-4-5-6-7-8-9-10-11-12-13-14-

APPENDIX ABASIC ISSUE ITEMS LISTBasic issue items list will be published at a later date.A-1

APPENDIX BMAINTENANCE ALLOCATION CHARTSection I.INTRODUCTIONB-1. GeneralThis Maintenance Allocation Chart designates overall responsibilityfor the per

j.Overhaul. Normally, the highest degree of maintenance performed bythe Army in order to minimize tine work in process is consistent with qualityand e

SECTION IIB -3

APPENDIX CREPAIR PARTS LISTC-1. This appendix provides a list of repair parts for maintenance supportof the equipment. The parts along with their desc

Table C-1. Repair Parts ListNomenclature———— .BULB INCANDBULB INCANDXSTR SP8481XSTR SIL 4!YJ BXSTR 2N3053XSTX SIL 2N.305SXSTR SIL NPNXSTR 2!N3:+41XSTR

TM 9-6625-2467-15By Order of the Secretary of the Army:W. C. WESTMORELAND,General, United States Army,Official:Chief of Staff.KENNETH G. WICKHAM,Major

WARNINGHIGH VOLTAGEis used in the operation of this equipment.DEATH ON CONTACTmay result if personnel fail to observe safety precautions.Learn the are

Fig. 2-10. 1 MHz MARKERS OUT (Phase lock reference) connector.DISPERSION 1 MHz/div.d. Adjust the DISPERSION-CAL for 1 marker/division.Use the Horizont

SECTION 9. DIAGRAMSMECHANICAL PARTS LIST ILLUSTRATIONSACCESSORIES

9-1

9-3

9-5

9-7

9-9

9-11

9-13

Fig. 2-12. VERTICAL DISPLAY Modes showing a 100 MHz carriersignal modulated by 20 kHz.Fig. 2-13. Measuring timing between pulses.With the DISPERSION c

9-15

9-17

9-19

9-21

9-23

9-25

9-27

FIG. 19-29

FIG. 2 REAR9-31

9-33FIG. 3 IF CHASSIS & PHASE LOCK ASSEMBLIES

Fig. 2-14. To trigger the analyzer from the display requires 0.2divisions of signal. Tune the spectrum null point away from thesweep starting point, w

FIG. 4 POWER CHASSIS9-35

FIG. 5 TIME/DIV SWITCH & OSCILLATOR ASSEMBLIES9-37

FIG. 6 CRT SHIELD ASSEMBLY9-39

FIG. 7 CABINET ASSEMBLY & HANDLE9-41

FIG. 8 491STANDARD ACCESSORIESFIG. 8 491 STANDARD ACCESSORIES9-43

PIN: 028017-000

This fine document...Was brought to you by me: Liberated Manuals -- free army and government manualsWhy do I do it? I am tired of sleazy CD-ROM sell

erence level of the output amplifier. This DC level changesas the FINE RF CENTER FREQ control is rotated and shiftsIPhase lock operation is establishe

2-16Fig. 2-17. Control set-up chart.

Fig. 2-18. Spectrum of an amplitude modulated signal. Sidebandamplitude is ½ the percentage of modulation. This spectrum shows100% modulation.3. Decre

Fig. 2-20. Formation of a pulse modulated signal spectrum.Frequency Modulated Signal SpectrumWhen a CW signal FC is frequency modulated at a rate(Fm),

Fig. 2-21. Pulse width and PRF effects on pulse modulated spectrum.Identification and Frequency Measurement ofDisplayed SignalsBandpass and dispersion

Fig. 2-22. Pulse shaping effects on the pulse spectrum.2-20Fig. 2-23. Frequency difference measurement between two signals.cillator fundamental. If an

The following are basic applications for the Type 491and are presented to illustrate some of these uses in theelectronics field.Relative Amplitude Mea

This manualreproduced byTECHNICAL MANUAL))No. 9-6625-2467-15 )contains copyright materialpermission of TEKTRONIX, Inc.TM 9-6625-2467-15HEADQUARTERSDEP

Fig, 2-25 Frequency modulated displays.Fig. 2-26. Amplitude modulated displays.Long term stability measurements require a recorder or aFrequency Stabi

Over modulation will produce extra sideband frequencies.The spectrum is very similar to multi-frequency modulation.Over modulation, however, is usuall

2. A visual means is provided to tune the transmittingsystem and obtain most of the output power within the fre-quency range of the receiver bandwidt

SECTION 3CIRCUIT DESCRIPTIONIntroductionThe Type 491 Spectrum Analyzer is a swept IF type ana-lyzer covering the frequency range from 10 MHz to 40 GHz

Fig. 3-1. Function block diagram of the Type 491.3-2

Band B: The oscillator for band B is similar to band Aoscillator. The fundamental frequency range 470 MHz to 1100MHz and the 2nd harmonic of the oscil

The back bias across D1116 is controlled by INT REF FREQcontrol R1106. This change in back bias increases or de-creases the diode capacity and shifts

CHECK switch to the vertical deflection system. At zero beat,the output signal amplitude snaps to a minimum and the cir-cuit locks the local oscillato

resultant feedback signal from a frequency to voltage con-verter and ramp generator. Any differential between thetwo signals is a voltage output that

Fig. 3-6. Simplified diagram of the transformer (T330-T331) cir-cuit from the swept oscillator to the push-pull amplifier Q340-Q350.so the dirve signa

iiFig. 1-1. The Type 491Spectrum Analyzer.

The discriminator for the kHz/DIV position of the DISPER-SION RANGE switch consists of tuned circuits which operatemuch like the tuned transmission li

its base to emitter Q420. A feedback winding on T424, tois tuned to 5 MHz and couples the signal to the 5 MHz IFthe hose of Q420, provides the neutral

Fig. 3-10. Block diagram of the video detector and vertical amplifier.3-10

Variable Resolution AmplifierThe variable resolution amplifier is designed to varythe bandwidth of the 5 MHz IF from approximately 100 kHzto less than

The input signal is attenuated through R617 and the inputimpedance to Q620, so that an approximate 5 division dis-play in the LIN position will provid

circuit. Triggering becomes a funtion of the trigger signalamplitude and the slope of the trigger signal.The Trig Level Centering R724 is adjusted wit

and D1016, is configured as a voltage doubler. The circuitprovides approximately -3700 volts for the cathode ofthe CRT and is the reference voltage fo

Overload protection is provided by fuse F900 ond F902.Thermal cutout TK902 in the primary circuit of T900 opensthe transformer primary circuit if the

SECTION 4MAINTENANCEIntroductionThis section of the manual pertains to the maintenanceand troubleshooting of the Type 491. The first portion ofthe sec

SECTION 1CHARACTERISTICSThe Type 491 Spectrum Analyzer is a wide band,general purpose portable spectrum analyzer with an RFcenter frequency range from

The gears should be lubricated with a high quality lubri-cant such as COSMOLUBE No. 102, (Tektronix Part No.006-1229-00). The bearing surfaces and dri

as the RF Section) is assigned a particular series of num-bers. Table 4-1 lists the assigned component numbers forthe various circuits,Switch wafers a

ponent can then be correctly soldered in its place, Observesoldering precautions and techniques as described in Solder-ing Techniques later in this se

Fig. 4-4. Power Supply Circuit board assembly with wiring color code.4-5

Fig. 4-5. Horizontal Display circuit board assembly showing color code to pin connectors.4-6

Fig. 4-6. IF Control board assembly. Wiring color code to pin connector.4-7

Fig. 4-7. Honeycomb assembly and wire color code to the pinconnector.3. Turn the Type 491 on its side (see Fig. 4-11). Removethe nylon rocker arm from

Fig. 4-9. Phase lock assembly and wiring color code to the pin connector.Fig. 4-10. Mounting screws for the honeycomb assembly,To replace the CRT, rev

Fig. 4-11. Honeycomb assembly open and ready for voltage and waveform measurements.4. Loosen the two nuts that secure the back of the switchassembly t

Fig. 4-13. Removing the TIME/DIV switch. Local oscillator assemblyremoved to show the location of the mounting hardware.After the assembly is remounte

ELECTRICAL CHARACTERISTICS (cont)CharacteristicPerformance RequirementSupplemental InformationDispersionMHz/DIV RANGERange.2 MHz/Div to 10 MHz/Div In

Fig. 4-15. Removing the Phase Lock assembly.Removing the Phase Lock Assembly1. Repeat steps 1 through 3 of the above procedure, thenremove the knob an

Fig. 4-16. Removing the phase-lock assembly board.1. Band A Mixer Diodesa. Disconnect the sub-miniature connectors, remove thetwo mounting screws and

Fig. 4-17. Preparation to remove the oscillator and tuner assembly.b. Slide the oscillator tube out of the mounting flanges bygently pushing the tube

Fig. 4-19. Band A and B local oscillator assemblies.Replacing Components on the Circuit BoardsIt is best to remove the circuit board assembly to repla

Fig. 4-20A. Tube subassembly removal procedure.4-16

Fig. 4-20B. Tube subassembly installation procedure.4-17

7. Clip off any excess leads that protrude through thehole in the board.8. If necessary, clean the area around the soldered con-nection with a flux-re

to start with the power supply circuit, then proceed consecu-tively from one circuit to the next.Once the circuit has been isolated, refer to the Circ

Fig. 4-22. Power supply board assembly with component call out.4-20

Fig. 4-23 Vertical Amplifier and Blanking board assembly with component call out.4-21

CharacteristicTube TypePhosphorAccelerating PotentialGraticule TypeAreaIlluminationUnblinkingTIME BASECharacteristicPerformance Requirement Supplement

Fig. 4-24. IF control board assembly with component call out.4-22

Fig. 4-24. IF control board assembly with component call out.4-23

Fig. 4-25. Horizontal display board with component call out.4-24

Fig. 4-25. Horizontal display board with component call out.4-25

Fig. 4-26. Phase lock board with component call out.4-26

SECTION 5PERFORMANCE CHECKThis section of the manual provides a means of checkingthe performance of the Type 491. It is intended to checkthe calibrati

Hewlett-PackardHewlett-PackardHewlett-PackardHewlett-PackardHewlett-PackardMX292B Wave-guide to coaxial adapter.MP 292B Wave-guide to coaxial adapter.

6. Check Saw Out Signal Amplitudea. Requirement—SAW OUT signal amplitude is 70 to90 mV.b. Connect the test oscilloscope probe to the SAW OUTconnector

TABLE 5-110. Check Internal Triggeringa. Requirement-Sweep must trigger on 0.2 division signalamplitude.b. With 1 ms and 10 ns markers applied as in s

play linearity must remain within listed specifications ofTable 5-2 to the + and - 25 MHz positions.g. Center the coarse IF CENTER FREQ control. Set t

CharacteristicTemperatureOperatingNon-operatingAltitudeOperatingNon-operatingHumidityNon-operatingElectromagnetic Interference (EMI)Radiated Interfere

TABLE 5-2Fig. 5-4. Display pattern when resolution is correctly adjusted.5-614. Check Dispersion Accuracy of kHz/divSelectionsRequirement: Dispersion

Fig. 5-5 Equipment block diagram showing setup to check attenuator accuracy.TABLE 5-3Decrease the sweep rate as the dispersion is decreasedand increas

TABLE 5-4aLIN; ≥26δΒ.LOG; ≥40 dB.SQ LAW; ≥13δΒb. Apply 200 MHz signal that has an amplitude less than-40 dBm, from a VHF Signal Generator that has a c

d. Adjust the GAIN control clockwise until the signalamplitude is again 8 divisions. This checks that the rangeof the control equals or exceeds 50 dB.

from 10 MHz to 12.4 GHz over 50 MHz dispersion on band Aand over 100 MHz dispersion for bands B and C to 12.4GHz. 6 dB maximum amplitude variation fro

a. Requirement-Dial accuracy within ± (2 MHz + 1%of dial reading), sensitivity within the specified limits listed inTable 5-7. Phase lock must operate

towards the center of the display, merge over the IF feed-through response than separate and move off the screen,as the center frequency is tuned thro

TABLE 5-7Suggested SignalSensitivity (50 W source)GeneratorEqual to or better thanDial Accuracy(Refer to equipment list)FrequencyBand100 kHz1 kHzCheck

SECTION 6CALIBRATIONIntroductionThis spectrum analyzer is a stable laboratory instrumentwhich should not require frequent recalibration. Perform-ance

SECTION 2OPERATING INSTRUCTIONSIntroductionA Spectrum Analyzer is an instrument that graphicallypresents a plot of signal amplitude as a function of f

Fig. 6-1. Test equipment recommended for calibration of the Type 491.6-2

Fig. 6-2. Test equipment recommended to measure thedial accuracy, receiver sensitivity and response flatness.6-3

Fig. 6-3. Recommended adjustment tools.20. Two (2) adapters, BNC male to N female2. TektronixPart No. 103-0058-00.21. Two (2) adapters, BNC female to

CALIBRATION RECORD AND INDEXThis Abridged Calibration Procedure is provided to aid inchecking the operation of the Type 491/R491. It may be usedas a c

amplitude with no more than 3 dB dip in the center,Set the RESOLUTION control fully clockwise. Adjustthe 100 kHz Resolution Cal R543, for a resolution

CALIBRATION PROCEDUREGeneralIn the following procedure, a test equipment setup is shownfor each major setup change. Complete control settings areliste

Fig. 6-4. Equipment setup for adjusting and checking the low and high voltage power supplies.Type 491CRT ControlsINTENSITYCCWFOCUS MidrangeSCALE ILLUM

a. Equipment setup is shown in Fig. 6-4.b. Turn the POWER switch to ON position, then connecta calibrated voltmeter between pin K on the Vertical Ampl

c. Connect the voltmeter between pin 14 of the CRT basesocket and chassis ground. (See Fig. 6-6). Set the voltmeterrange to measure approximately 4000

CAUTIONWhen changing the input power selector range,the power should be removed by either turningthe autotransformer power switch to off, or byc. Adju