Tektronix 494AP service manual O o o a a, DB2, DB7-O DB3-DBO

Malntenance- 494A/4g4Ap

Servlce Vol. 1

Table 6-13{cont)

Data Bits

Table 6-13 (cont)

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7 6 5 4 9 2 1 0	Descriptlon
G. Sweep
	Holdoff,Interrupt,Trigger (0F.0)

DataBits

7 6 5 4 3 2 1 0

H.SpanAttenuator (cont)

Descrlption

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x x 0 0 x x x x x x 0 l x x x x x x l 0 x x x x x x x x 0 0 x x x x x x 0 l x x x x x x l 0 x x x x x x l l x x x x x x x x l x x x x x x x x l

x x x 1 1 0 1

x x x 1 O 1 1

x x x 1 0 0 1

x x x 0 1 0 1

x x x 0 0 1 1

x x x 0 0 0 1

x x x 1 1 0 0

Short sweep holdoff Mediumsweepholdofi Longsweepholdoff Freerun triggermode Internaltrigger mode Extemaltrigg€rmode Linetriggermod€ Enableend-of-sweepinterrupt SingleSweepMode

SweepRatoand Mode (0F.1)

20 ps Time/Div

50 ps Time/Div

100ps Time/Div

200 ps Time/Div

500ps Time/Div

1 rns Time/Div

2 ms Time/Div

l x x x x x x x

0 x x x x x x x x O 0 x x x x x x 0 l x x x x x x l 0 x x x x x x x x 0 0 x x x

x x x 0 l x x x

x x x l 0 x x x

DB2

DBl, DBO

l. 1st LO Driver

SpanMagnitudeand Attenuator (76)

of U3032is +1 Gainof U3032is -1

x1,0 sweepdecadeattenuator

x0.1 sweepdecadeattenuator

x0.01swe€pdecadeattenuator

lst LO maincoil outputselectand calibration

1st LO FM coil output selectand calibration

2nd LO output selectand calibra- tion

For futureuse

Uppertwo bitsof attenuationcode

lst LO DriverFunctions(72)

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x x x 1 0 1 0
x x x 1 0 0 0
x x x 0 1 0 0
x x x 0 O 1 0
x x x 0 0 0 0
x x x 1 1 0 0	0
x x x 1 0 1 0	0
x x x 1 0 0 0	0
x x x 0 1 0 0	0
x x x 0 0 1 0	0
x x x 0 0 0 0	0
x x x 1 1 1 1	1
x x x 0 1 1 1	1

DB7-O

DB3-DBO

x x x 0 x x x x

5 ms Time/Div

10 ms Time/Div

20 ms Time/Div

50 ms Time/Div

100ms Time/Div

200 ms Time/Div

500 ms Time/Div

1 s Time/Div

2 s Time/Div

5 s Time/Div

10 s Time/Div

Manual

External

0F.2(U104s)

MarkerDACvaluebits

0F.3(U103s)

MarkerDACvaluebits 9F

PollBit

l x x x x x x x 0 x x x x x x x x l x x x x x x x 0 x x x x x x

x x l x x x x x x x 0 x x x x x x x x l x x x x

x x x 0 x x x x x x x x l x x x x x x x 0 x x x

x x x x x x x x x x x x x x x x x x x x x x x x x 0 x x x x x l

Normalspanmode spanmode

sweepvoltageto driver Disconnect sweep voltage to driver

Driveroff {for degauss) Driveron

Filter on at driver output (for unphase'lockednarrowspans) Filteroff at driveroutput Externalmixerdisconnected External mixer connected (con- nected in bands 1-5 if external mixer selected;alwaysconnected in higherbands)

1 0 Internalmixerbiasfor Band1

1 0 Internalmixerbiasfor Band2

1 0 Internalmixerbiasfor Band3

0 1 Internalmixerbiasfor Band4

1 1 lnternalmixerbiasfor Band5

1 1 No inlernalmixerbias selected

PEAKingControl(7E)

3

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H.Span Attenuator

DB7-DBO

Span Magnitude (75)

Lower 8 bits of 10-bit attenua- tion code (000 is max attenua- tion)

0 x x x x x x x SteersDB4-DB0to upperlatch

x 0 x x x x x x SteersDBs-DBoto lowerlatch DBs-DBO1 sent to DB4 of upper latch dis-

ablesfront-panelPEAKingcontrol; DB3-DB0 of upper latch and DBS-DBOof lower latch form 10- bit inputto DACfor programmable peakingvoltage

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6-60

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