Tektronix 494AP service manual Qlglptv to 50Hz, andVERlCnl.drdpr-ry

I

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t

g. Checkthe resolutionbandwidthsand shapefac_

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tors for the 100kHz (300ftHafor OptionbA, 10 kHz,

t

1 kHz,and 100Hz fitters. Shapefactlistroufdbe 7.5:1

or less.

o

h. RESET

'IO

thE RESOLUTION

BANDWIDTHtO

HZ,

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qlglptv to 50Hz, andVERlCnl.'drdpr-ry

dB/Dlv.

ro 2

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i. Checkthe resolutionbandwidthand shapefactor

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of the 10 Hz fitter. Shapefactorshouldi"

iZrt or tess.

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12. Check Catibrator Output

o

(-20 dBm *0.3 dB)

a

Apply a 100MHz signal to the power meter

through

a 3 dB attenuatoranOa SOO

Set the

a

generatoroutputlevelfor a reading

_"d;t"20.

powermeter.

of

dBm on the

a

b. Disconnectthe power meterfrom

the signalgen_

a

erator,and connect

the reference

part a to the RF tNpUT,

signatestablished

in

O

throughthd same50O cable

and3 dB attenuator.

a

c. Setthe SpectrumAnalyzercontrolsas follows:

a

CENTERFREQUENCY

100MHz

SPAN/DIV

o

RESOLUTION

100kHz

BANDWIDTH 1 MHz

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REFLEVEL

- 18 dBm

VERTICALDISPLAY

2 dBlDtv

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TfME/Dlv

AUTO

PEAK/AVERAGE

FullyClockwise

o

; .d. .Sel

the spectrumanalyzer

a

VERTICALDlSpLAy

factorto th€ AA mode by pressingfiruE.-'Set

o

LEVELsuchthat the top'oi

the REF

the siinat is'ona graticute

line near the top of the crt. nesJt ttre neF LEVELto

o

0.99gP by pressing

activating

FNEtwice. Storettre displayby

a

SAVEA.

_e.

Removethe reference

a

signaffrornthe nF tNpUT

and connectthe CAL OU.Tsignll in its placeusingthe

I

samecablethatwasusedin partb of thisstep.

f. ActivateVIEWB and VIEWA.

a

g. Checkthat the amplitude

o

difference

VIEWB and

betweenthe

SAVEA disptays(CALOUi iignaranOthe

reference)

I

doesnot exceedb.S'Og.

o

o

13. Check Noise Sidebands

o

(At least-70dBc at 30Xthe selected

bandwidthfor

, resolutionbandwidthsof 100Hz and 10 Hz)

o

(At least-75dBc at gOXthe selectedbandwidthfor

I

allotherresolulion

bandwidths)

Apptythe

O

1.

CALOUTsignat

to the RF tNpUT.Set

the SpectrumAnalyzercontrolsas follows:

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o

PerlormanceCheckprocedure_ 4g4Ll4g4ApServlceVot.1

CENTERFREOUENCY	100MHz
sPAN/DtV	1 kHz
RESOLUTIONBANDWTDTH
	100Hz
REFLEVEL	-40 dBm
VERTICALDISPLAY	10dB/Dtv
TrME/DtV	AUTO
WIDEVIDEOFTLTER
	On

b.Checkthat the amplitudeof th€ noisesidebands is at least 50 dB down from the referencelev€l at g0 times the resolutionbandwidth(3 divisionsaway from the centerfrequencyposition).SeeFigure4-10.

c.Reset the spAN/Dlv to 1ooHz and set the RESOLUTTONBANDWTDTHto 10 Hz.

d.check that the amplitudeof the noisesidebands is at least 50 dB down from the referencelevelat 30 timesthe resolutionbandwidth.

€. Reset the spAN/Dtv to 10 kHz and set the RESOLUTIONBANDWIDTHto 1 kHz.

f.Checkthat the amplitudeof the noisesidebands is at least 55 dB down from the referencelevelat O0 timesthe resolutionbandwidth.

E	-St	cd	ra.C	rttr	-
					rq	n
						{
						{
						-
						_tt
			r	l4ftr		-
		rrl(	I		I	-rl
			\
						-
						-il4
						- t t
			t	ll{l
						556034

Figure 4-10. Typical disptay for measuring noas€sidebands.

4-15

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