Adjustment Procedure

h. Selectthesesettings: FREOUENCY 600 MHz FREQUENCY SPAN/DIV 100MHz RESOLUTION BANDWIDTHAuto -20 dBm REFLEVEL MINRFATTEN OdB VERTICAL DISPLAY 1OdB/DIV NARROW VIDEOFILTER Off VIEWA/B Off PEAK/AVERAGE FullyCountercfockwise AdjustInputoflset,R1055on the Horizontal DigitarStorageboard,to positionof the storedsignalto thatof the non,stored matchthe horizontal signalat centerscreen. k . f{ust InputGain,R1060onthe Horizontal DigitalStorageboard(Figure

5-7),to matchthe horizontal positionol lhe storedsignalto thatof thb nonstoredsignalnearthe rightedgeof the screen.

5. Adjust Sweep Timing R1062on the Sweepboard.

NOTE WhenadjustingOption42 instruments,the outputof the FunctianGenerator mustbe connectedto the PENLIFTconnectorat the rearof the instrument, ratherthanas shownin Figure5-4. Be sure to groundpin I of the ACCESSORIES connectorwhenusingthe PENL\FTconnectarin this manner. a. Connectthe testequipment as shownin Figure5-8. Setthe following SpectrumAnalyzercontrols : FREQSPAN/DIV TIMSDIV TRIGGERING

10MHzorless 1 0m s EXT

b. Connecta jumperbetweenpins1 and5 (ExtVideoSelectandGround respectively) on the ACCESSORIES connector. c. set the TimeMarkGenerator controlsfor 10 mstimemarks. d. e_ditpt_Sryeep Timing,R1062(seeFigure5-9for 492NPand Figure5-5for 492BlPr, for 1 markerperdivision.(UseHorizontal Positionadjustment to alignmarkerswithgraticulelines.) e. Checkthe accuracyof the remaining TlMgDlV selections. Erroroverthe centereightdivisionsmustnotexceedx5 %. f.

4 9 2 Al P

&

492glP

Se rv i c e ,

Vo l.

Resetthe TlMgDlVto AUTOand FREQSPAN/D|V to MAX,andactivate AUTORESOLN.ReturnTriggering to FREERUN. Disconnect the timemarkgeneratorfromthe Spestrum Analyzer.Removethejumperbetween pins1 and5 of the ACCESSORIES conneclor.Reposition the traceif movedin partd.

1

5-13

Adjustment Procedure

To MARKER/VIDEO

To HORIZ/TRf G -\l/

: :

:

g

Time Mark Generator

I

rtttlG?rt cltrtlrrtilFrEt-n-EtILg

t3

rarlt

Marker Out

Connect J umper Between P i n s 1 &

Trigger Out

Partial Back Panel Showing J104 Accessory Connector

Flgure 5-8: Test equlpment setup for adlustlng sweep tlmlng.

W*P1o2o

U

Figure 5-9: Sweep board tlming adjustment and test polnt locations.

5 - 14

492AlP &

492BlP $ervice, Vol, 1

Adjustment Procedure

1 s t L O Tune Coll 1 s t L O F M C o t l R1065 Sweep H1071

Swee

I Sp"n Attenuator

Sweep Offset R 10 6 3

r P 1 o 3 s{ l

T F;E,BOArd

lc"n,",,Frequency

2 n d L O S w eep R 1067

IT

e R3040:

R4040-

R1028

Rl032

C o n t r o l Board

JJ\ T P 10 s 8 I

I lfl-'

1st LO Driver

I I H1031

r-i

R 10 3 4

Board

I

R 10 3 2

Figure 5-10: Frequency control system test point and adjustment locatlons.

6, Adjust Frequency Control System R1063,R1065,R1067,andR1071on the SpanAttenuator board. R1031,R1032,andR1034on the 1stLO Driverboard. R1028,R1032,R3040,and F14040 on the CenterFrequency Controf board. C1013C2011 on the Controlled oscillator board. R1062on the Sweepboard. TheSpectrumAnalyzerhasa procedure in firmwareforcalibrating the frequency controlsystem.However,it is possiblethat someadjustments may notbe adjustedproperly,whichmaycausethe microcomputer to displayan errormessage.lf thisoccurs,bypassthe stepand returnto the calibration routine. Testequipment requiredforthissteparc a Voltmeter, TimeMarkGenerator, and Frequency Counter. a. Selectthe followingSpectrumAnalyzersettings: FREQUENCY FREQUENCY SPAN/DIV TRIGGERING

O.OMHz 5 MHz FREERUN

h. Connecta shortingstrapfromTP1035,on the SpanAttenuator board,to chassisground(Figure.S-tO). MonitorTP1073withthe DigitalVottmeter. c. AdjustSweepOffsetR1063(Figure5-10)for 0.00V. d. Remove the shorting straplromTP1035.Press PULSE STRETCHER andselectitem1 (FREOUENCY LOOPSCAL),thenitem0 (OVERALLSYSTEM)fromthe menus.Performthe calibration stepsas ("coNNEcTA DVMTO Tp1058ON THE 1STLO DBTVER directed BOARDANDGROUND"), etc. 4gzAlP &

gzBlP Service, Vol, 1

5-15

A dj u s t m e n t

P r o c e d ur e

1) tf a "cALlBRATtoN srEP cANNoTBEOOMPLETED" messageis displayed, bypassthe step,performthe otheradjustments then return to the adjustment andtry tg bringthe adjustment in range. lf the problempersists,referto Troubleshooting the FrequencyControl System,in the Maintenance section. e. Adjustthe SPANIDIV accuracyas follows: 1) Applythe cAL OUTsignalrorheRF INPUT,setthe FREQUENCy to 600MHZ,FREQSPAN/DIV tO1OOMHZ,ANdSEtthEREFLEVELtO displaythe markers. 2) fdiust TuneCoilSwp R1065,on the SpanAttenuator board(Figure 5-10)for onemarkerperdivisionoverthe centereightdivisions ot tne graticule.Resetthe CENTERFREQUENCY as necessary to alignthe rnarkers. 3) RemovetheCALOUTsignalandapply0.2ps timemaftsfromthe Time MarkGenerator to the RFINPUT. 4\ Setthe FREQSPAN/DIV to 5 MHz,REFLEVELto +10dBm,and FREQUENCY to about10MHz. 5) Adjustthe1stLO FMCoilSwpR1071(Figure5-10)for 1 markerldivision overthe centereightdivisionsof the display. 6) Setthe FREQSPAN/DIV to 20 kHzandapply50 ps markersfromthe TimeMarkGenerator. 7) Adjustthe 2nd LO Sweep,R1067,for one markerldivision overthe centereightdivisions. f.

AdjustDot Markerpositionas follows: 1) Disconnect the CALOUTsignalfromthe RF INPUT. 2l Press RESET. 3) AdiustDot PositionR1062on the Sweepboard(Figure5-9)to position the dot markeroverthe startspur.

7. Adjust Log Amplifier R4020,R4052,R4471,R4081,and R1085on the 49?NP Log Amplifier board. R1012,R1025,R 1 0 3 0 ,R 1 0 3 7 a, n d R1060 on the 492BlP Log Arnplifier board.

NOTE Useonlyan insulatedscrewdriver or tuningtool,suchas TektronixPartNumber 003-0675-00, to maketheseadjustments. a. Preliminary setup:

5 - 16

4gZAlP &

AgzBtP Service, Vol.

1

Adjustment Procedure

1) lpttle r_qgfactorsro zeroby pressingPULSESTRETCHER FUNCTIONSJ and item5 (INTERNAL selecting MEASUREMENT RESULTS), then item2 (sETRESULTS TO "UNCALED"). 2) RemoveLevelerDisableplugP3035on the VideoProcessor board (Figure 5-11). 3) SwitchPOWERoff. 4) Removethe LogAmplifier andDetector boardassembry fromthe instrument; thenremovethe shieldso adjustments are accessible. 5) Replace the assembly in the instrument and switchPOWERbackon. b . connectthetestequipment as shownin Figure5-12. (P621mustbe

removedin orderto accessJ621on the LogAmplilierboard, See Figure 5-13.)

c. Setthe SpectrumAnalyzercontrolsas lollows: FREQUENCY

2MHz

FREQUENCYSPAN/DIV

ZMHz

AUTORESOLN REFLEVEL MINRFATTEN VERTICAL DISPLAY VIEWA/B TIMSDIV

On -60 dBm 0dB 10 dB/Dtv off 1 0m s

d . Centerthe twofrontpanelLOGandAlri'PLCAL adjustments.Setthe

signalgeneratorcontrolsfor a 10 MHz/+6dBm output.Set the step attenuators for 50 dB of attenuation.

e . Position the displayat a graticulereference linewiththeverticalPO$|T|ON control; thenswitchthe REFLEVELfrom-60 dBmto -110 dBmin decade steps. f.

Adiustthef rontpanelLOGCALso each10 dB stepequalsonedivision.

g . set the REFLEVELto -20 dBmandthe stepattenuators for 0 dB

Resetverticalpositionto a graticulelineif necessary. attenuation.

h.

Increase the attenuation throughthe stepattenuators in 10 dB increments ro 70 dB. 4oiqstthe Log Gain,R4020tar 492AlPor R102stor 49zB/p (Figure 5-13)so each10 dB increment of attenuation resultsin one majordivision of changeon the display. Resetvgrlic_alnosition by temporarily removingthe signalandsettingthe verticalPOSITION controlto alignthe baselineto the bottomgraticuleline. Returnthe stepattenuator to 0 dB.

k . 4djgslInputRef Lvl, n4a71for 492AtPor R1097for 4928/p (Figure

5-13)for minimumamplitude changebetweenthe10 dB/DtVanOa OA/OIV settingswhilealternately switching the vERTICALDlSpLAybetween 10dB/DlVand2 dB/DlV.

492AlP &

492glP Servlce, Vot. 1

5-17

Adjustment Procedure

Figure 5-11: P3035 0n the video processor board.

BNC to smb Adapter

To J621 on Log & Vldeo Ampl Board

10 MHz Leveled Slgnal

Generator,0 to -10 dBrn

@"@"@,@"@ Spectrum Analyzer Under Test

10 dB Step Attenuator

dB Step Attenuator

Flgure 5'12: Test equlpment setup for adjusting the Log Amplifler.

5-18

492AlP &

492BlP Servlce. Vol. 1

Adjustment Procedure l.

Fine-tune the iog Gainas follows: 1) Activate2 dBlDlVandadd 10dB of attenualion. with is short,adjustthegainslightly Zt lf the 10 dB step(fivedivisions) then R4020for 492AlPor R1025for 4928/Pin the samedirection; for R4071 attenuation and adiust of external 10 dB removethe gZAlPor R1A37br 492BlPfor equaldisplayamplitude when in the 10 dB/DlVand 2 dB/DlVsettings. t1 minor 3) Repeatthischeckuntilthe 10 dB stepis fivedivisions division. 4) Activate10 dB/DlVandrepeatpartito check10 dB logging.

removethe inputsignalto the Log m. Activate2 dB/DlVand momentarily line;thenreturnthe to the bottomgraticule alignthe baseline Amplifier; signalto the LogAmPlifier. n. AdjustoutputRel Lvl, R4081for 492AlPor R1030for 4928/P (Figure (eightdivisions) display. 5-13)lor a full-screen for 40 dB of o. Switchto the 10 dB/DlVmodeand set the stepattenuators R1085for 492AlPor Log Fidelity attenuation.AdjustLog Linearity, R1060for 4928/P(Figure5-13)so the displayis mid-screen. settingwas requiredin parto, repeat p. lf a largechangein the adjustment partsm througho becauseof interaction. q. Checkthe accuracyof 10 dB/DlVand2 dB/DlVdisplaymodesas follows: in 10 dB stepslor 10dB/DlVmodeand 1 dB stepsfor 1) Addattenuation the 2 dB/DlVrnode. t0.25 minor Z) Checkthateach10 dB/DlVdisplaystepis 1 majordivision, (10dB steps),andeach2 dB/DlVdisplaystepis 0.5division, divisions +0.5minordivision(1 dB steps).Youmayadjustthe signalgenerator outputto establisha newreferencelevelaftereachstep. to 0 dB and adjustthe generatoroutputlevel A) Resetthe stepattenuator disPlaY. for full-screen for 10 dB/DlV,and 16 dB tor 2 dB/DlV, 4,t ' Add80 dB of stepattenuation to measurethe worstcaseerroroverthe dynamicrange. Errormustnot +1.0dB overthe 16 dB exceed*1.5 dB overthefirst80 dB of range,or range. adiustgain 5). lf the 10 dB stepin the 2 dB/Dlvmodeis outof tolerance, readjust the Input 4928/P for and R1025 492AlP or with R4020for Ref Lvl, R4071for 492AlP or R1037for 4928/P. to 10 dB and activate2 dB/DlV. r. Setthe stepattenuators outputfor a s. Setthe RefLevelto-15 dBmandadjustthe signalgenerator displayin the 2 dB/DlVmode. full-screen

492AlP &

492BlP Serviee, Vol. 1

" . 5 - 1 9

A d j u s t m e n l P r o c e d ur e

Un. Bel. F4052

lnput Ref. Level R4071

Log Unearity R1085

P1105 (J620) Log Galn R4020 P2105 (J621) Output Ref. Level R4081

I-t l-r A. 492AlP Log & Video Amptifier Board.

Lln. Bal. 81012

Log Gain R1025

OutputRef. LevelRl030

Input Ret LevelR1037

Log Fidelity R1060

T T B.492BlPLog & VideoAmpliflerBoard. Figure 5-13: Log and Video Amplifler test point and adjustment locailons.

5-20

492AtP &

492BlP Service,

'Vol.

1

Adiustment Procedure

From3rd Converter

VR 2nd Filter Select

(A)

J683

10 MHz

@-25 dBm (B) Figure 5-14: Test equlpment setup for adjustlng the Varlable Resolutlon module. t.

R4052for tlg2AlPor R1012tor PressLINandadjustLinModeBalance, (Figure 492BlP 5-13)for a full-screen display.Amplitude of LlN,2 dBlDlV, and10dB/DlVdisplayshouldnowbe the same.

U.

CheckLINdisplaylinearityby adding6 dB, 12 dB, and 18 dB of attenuation andnotethe displaystepdownfromfullscreento, 410.4,6 +0.4,andT +4.4divisions.

V.

Removethe signalgeneratorsignalconnectionto the LogAmplifierinput jackandreplaceP621,andrepeatparta subparts2 through5 in reverse orderto installlhe circuitboard.

8. Adjust Resolution Bandwidth and Shape Factor 492AlPadjustments- C1022,C2026,C5055,C5048,C3041,R1065, R3015,R3029,R3033,and R4025on the VR ZndFilterSelectboard C1026,C1033,C2037,C3023,C3035,C3050,R2025,and R3035on the VR 1stFilterSelect. 492BlPadiustments- C5055,C5048,C3041, R1065,R3015, R3029,R3033,and R4025on the VR 2nd FilterSelectboard. C1034,C1044,C1046,C2030,C3030,C3039,C3045,and R1027on the VR 1stFilterSelect. The3 dB downbandwidthof eachfiltersectionshouldbe as wideor slightly widerthanthe 6 dB downpointof the combinedtwo filtersections. Bandwidthand Gain,setthe Beforecalibrating the VariableResolution factorsto zeroby pressing PULSESTRETCHER and correction item5; thenitem2. selecting

NOTE The 1A0kHz filtersin eachsectionare alignedseparately;thena signalis appliedthroughboth the firstand second sections. The final adjustmentstrim filtershapeand bandwidth.Becauseof interaction,it is easyto offsetone filter to compensatefor anotherfilterthat is out of adjustment;therefore,only adiust eachfilter in smallincrements. 492AtP &

492BlP Service, Vol. 1

5-2I

A d j u s t m e n t P r o c e d ur e

a. Equipment setupis shownin Figure5-144. 1) RemovetheVariableResolution moduleand installit on an extender. 2) Removethe cableplugconnected to J683(inputto the second sectionof the rnodule). 3) Usingsmbmale-to-male adaptersandcoaxialcables,connectJOB2 (outputof the module)to J621,the inputto the LogAmptif ier. 4) UsingSMBmale-to-male adaptersandcoaxialcables,conneclP6gg (10 MHzoutputfromthe ThirdConverter, with redband)to J683(input to secondsectionof module). 5) Applythe cAL our signatto the RF |NPUT,andsetthe spectrum Analyzercontrolsasfollows: FREQUENCY 100MHz FREQUENCY SPAN/DIV 50 kHz(100kHztor Oprion07) RESOLUTION BANDWIDTH100kHz(300kHzfor Oprion07) -20 dBm REFLEVEL MINRFATTEN OdB VERTICAL DISPLAY 2 dB/DIV b. Resetthe REFLEVELfor a sevendivisionexcursion. c. AdjustC5055,C5048,andC3041on the VR 2nd FilterSelectboard (Figure5-15)forthe best100kHzfilterresponse (100kHzbandwidth, OdB down,thatis centered aroundmid-screen). Referto FigureS-16. d. Disconnect the 10 MHzThirdConverter signalfromJ683and connectthe ThirdConverter outputto J693(Figure5-148).Setthe REFERENCE LEVELas neededto maintaina 7-division display. e. Adjustc3023,c3035,c3050 on the 4gzAtp(C3045,C3039,and C3030for 4928lP)tor the best100kHzresponsecenteredaroundmidscreen(Figure5-17).

NOTE Sfeps f throughi anly apply to the 4928/P. lf your instrumentis a 4g2Np, proceedto partj. t.

Changethe FREQSPAN/DIV to 1 MHzandthe RESOLUTTON BANDWIDTH to 3 MHz. Resetthe REFLEVELto bringthe signal amplitude lo about7 divisions.

g. {djust the fourtuningscrews(capacitors) on the 110MHzBandpassFilter (FL36)for the best3 MHzfillerresponse(3 MHz1600kHz,6 dB down)that is centeredaboutmid-screen. h. Changethe FREQSPAN/DIV to 200kHzandthe RESOLUTTON BANDWIDTFI to 1 MHz. Resetthe REFLEVELto bringthe signal amplitude to about7 divisions. i.

5-22

AdjustC1034,C1044,andC1046on the VB 1st FilterSelectboard(Figure 5-18)for the best1 MHzfilterresponse(1 MHz6 dB down,centeredabout mid-screen).

4gZAtP &

4gZBtP Servlce, Vol. 1

Adjustment Procedure

JoB2----->

S

R106s

r Y

J683 R3o2e

O

R4025 s6'Jj",

Figure 5-15: Adjustments on the front of the 492BlP Varlable Hesolutlon module.

iSFENEilCE 15'81 IARKEi LEI'EL

CEilfER FNEOUETICY IAAKEN FBEOUE}ICY

TT'NE

*

-1gDBM

aP^'{/Dn

sOKHZ

100.000MH2

tw

BE'

4

\

t:

-14

: \

t :

I

I

s

I

I I ?3,,, a

a

t

t

I

t l

l

t

r

l

r

\

, l, ,

t

r r

, ,\,

a a

\

I I

I

t t

t

r

t

20DB

VEFT olsplAY

FF ltttN

0-1.8 FREO nalroE

l

I

t

I

i

a r r f

-tl

t t

t l

t

t

I

f

I

r

t

I

100KHZ

INT itt osc

t t

.I

i. tt,

t

zDBI

l

vtoEo NL?gF

BE$OLUNOH SAlilgwtO?H

Flgure 5-16: 100 kHz fllter centered.

492AlP &

492BlP Service, Vol. 1

5-23

Adjustment Procedure

NOTE Partsi ?nd k onlyapplyto the 492NP. lf your instrumentis a 4gZB/p,proceed to part l. j.

changerheFREQspAN/DtVro sookHzandthe RESoLUTtoN BANDWIDTH to 1 MHz. Resetthe REFLEVELto bringthe signal amplitude to about7 divisions.

k. {djustthethre.e tunlngscrews(capacitors) on the 110MHzBandpass Filter (FL36)forthebest3 MHzfilterresponse (1 MHz+200kHz,6 dB down)that is centeredaboutmid-screen. l.

changethe FREQSPAN/D|V to 2 kHzandthe RESoLUTtoN BANDWIDTH to 10 kHz. Reserthe REFLEVELto bringthe signal amplitude to about7 divisions,

m. AdjustC2a37for 492A/P(c2090for 492Btp)for the besr10 kHz responsecenteredaboutthe 1 kHz reference(Figure5-17), N. SEtthERESOLUTION BANDWIDTH IO1OO HZANdFREQSPAN/DIV tO 200Hz. Resetthe REFLEVELfor a 7 divisiondisplay. o. AdjustR4025(Figure5-15)formaximumsignatamptitude. p. Checkthe shape,bandwidth, andcentering of eachfilter.lf adjustment of the 100kHzf ilteris required, the 1stand ZndFilterSelectboarijsshoufd be adjustedseparately.Figure5-18showstypicalrespenseshapes. q. Levelthe gainof thefiltersasfollows: 1) Selectthesesettings: FREQUENCY 1 0 0M H z FREQSPAN/DIV 20 kHz RESOLUTION BANDWIDTH100kHz(300kHzlorOption07) -20 dBm REFLEVEL VIEWA/B on 2) Activate SAVEA to storethe 100kHzf ilteramplitude.Thisis the reference for all otherfilters. 3) 4qig{ allfiltersto the 100kHzlevelas perthefollowing tabte.Change FREQSPAN/DIV as necessary to maintaina suitabledisplay. Table 5.3: Filter Gain Leveling Adfustments. Filter

A dj u s t

3 MHz (492BlP 1 MHz (492BlP

R1027

1 MHz (492AtPOnty)

H1065

1 0k H z 1 kHz

100Hz

5-24

R3029 R3015

L o c a ti o n Figure5-15 Figure5-17 Figure5-15 Figure5-15 Figure5-15 Figure5-15

492AlP &

492BlP Service, Vot. 1

Adjustment Procedure

Input From 3rd Converter

I

Y

H2060 J693

c1034

@

R2045 (4e2BtP o n l y )

@

c1046

10 dB Gain

c1044

@ czoso10 kHz

Output To J683 On VR#2

Flgure 5-17; Adjustments on the rear of the Variable Resolutlon module.

9. Preset the VariableResolutionGain and Band L e v e li n g R2038(R1030for 492B/P)on the PostVR Amptifierboard. R3035on the 10 dB GainStepsboard. Rza23and R2060(R2045for 492BlP)on the 20 dB GainStepsboard. R20310n the VR #2 Motherboard.

NOTE TheLog Amplifiermustbe calibratedbeforeadjustingany VariabteResolutian gqirygettings.Log Amplifiercalibrationcan be verifiedby applyinga +6 dBm, 10MHz signalto the input (J621),of the Log Amplifier,and checkingfor futt screendisplaywith the nEF LEVELat -20 dBm. ResistorR2025is not used for the 492NP and 4928/P EpectrumAnalyzers. gainand bandleveling,setthe a. Beforeadjuslingthe VariableResolution correclion factorsto zeroby pressing PULSESTRETCHER andselecting menuitem2 "SETRESULTS TO UNCALED".

492AlP &

492BlP Servlee, Vol. 1

5-25

A d j u s t m e n t P r o c e d ur e

rt.ntrt

Adjust For

na

100 kHz Fllter

Flat Top