Tektronix 434, Инструкция по эксплуатации

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C irc u it D e s c rip tio n —4 3 4
E X T H O R IZ m ode o f o p e ra tio n . When the T IM E /D IV
s w itch is set to E X T H O R IZ , th e X signal is connected to
th e H o riz o n ta l A m p lifie r c ir c u it via th e E X T H O R IZ in p u t
c o n n e c to r on th e in s tru m e n t rear panel.
The C R T c ir c u it determ ines th e C R T in te n s ity by
sum m ing th e signal in p u ts fro m the IN T E N S IT Y c o n tro l,
Channel S w itc h c irc u it (chopped b la n k in g ), Sweep Genera­
to r (u n b la n k in g ), and th e Z A X IS in p u t c o n n e c to r. The
C R T c irc u it also co n ta in s th e c o n tro ls necessary f o r o pera­
tio n o f th e ca th o d e -ra y tu b e . T race storage is accom plished
b y the Storage c irc u it.
The Power S u p p ly c ir c u it provides all th e voltages
necessary fo r o p e ra tio n o f th is in s tru m e n t. T h e C a lib ra to r
c irc u it provides a square-wave o u tp u t w ith accurate a m p li­
tu d e and fre q u e n c y w h ic h can be used to check th e c a lib ra ­
tio n o f th e in s tru m e n t and the co m pensation o f probes.
C IR C U IT O P E R A T IO N
General
T h is section provides a d e ta iled d e s c rip tio n o f the elec­
tric a l o p e ra tio n and re la tio n s h ip o f the c irc u its in the 4 3 4 .
T he th e o ry o f o p e ra tio n fo r c irc u its u n iq u e to th is in s tru ­
m e n t is described in de ta il in th is discussion. C irc u its w h ic h
are c o m m o n ly used in th e e le ctro n ics in d u s try are n o t
described in d e ta il. I f m o re in fo rm a tio n is desired on these
c o m m o n ly used c irc u its , re fe r to the fo llo w in g te x tb o o k s :
T e k tro n ix C irc u it Concepts B ooks (ord e r fro m y o u r
local T e k tro n ix F ie ld O ffic e o r representative).
C a th o d e - R a y T ubes, T e k tro n ix Part N o. 0 62-
0 8 5 2 -0 1 .
H o riz o n ta l A m p lifie r C irc u its , T e k tro n ix Part No.
0 6 2 -1 1 4 4 -0 0 .
O scilloscope Trigger C irc u its , T e k tro n ix P art N o.
0 6 2 -1 0 5 6 -0 0 .
Power S u p p ly C irc u its , T e k tro n ix P art N o. 062-
0 8 8 8 -0 1 .
S w e e p G e n e ra to r C irc u its , T e k tro n ix P art No.
0 6 2 -1 0 9 8 -0 1 .
V e r tic a l A m p lifie r C irc u its , T e k tro n ix Part No.
0 6 2 -1 1 4 5 -0 0 .
P h i l l i p C u tle r , "S e m ic o n d u c to r C irc u it A n a ly s is ",
M c G ra w -H ill, N ew Y o rk , 1964.
L lo y d P. H u n te r (E d .), "H a n d b o o k o f S e m ic o n d u c to r
E le c tro n ic s ", second e d itio n , M c G ra w -H ill, New Y o rk ,
1962.
Jacob M illm a n and H e rb e rt T a u b , "P ulse, D ig ita l, and
S w itc h in g W a v e fo rm s ", M c G ra w -H ill, N ew Y o rk , 1965.
T h e fo llo w in g c ir c u it analysis is w ritte n around the
detailed b lo c k diagrams w h ic h are given fo r each m a jo r
c irc u it. These d e tailed b lo c k diagram s give th e names o f the
in d iv id u a l stages w ith in th e m a jo r c irc u its and show h o w
th e y are connected to g e th e r to fo rm th e m a jo r c irc u it. The
b lo c k diagram s also show th e in p u ts and o u tp u ts fo r each
c ir c u it and th e re la tio n s h ip o f the fro n t-p a n e l c o n tro ls to
th e in d iv id u a l stages. T h e c ir c u it diagram s fro m w h ich the
d e ta iled b lo c k diagram s are derived are show n in the
D iagram s section.
C H A N N E L 1 IN P U T AM P A N D PR EAM P
General
In p u t signals fo r v e rtica l d e fle c tio n on th e C R T can be
co n n e cte d to th e CH 1 c o n n e c to r. T h e Channel 1 In p u t
A m p and Preamp c irc u its p ro vid e c o n tro l o f in p u t c o u p lin g ,
ve rtic a l d e fle c tio n fa c to r, balance, ve rtica l p o s itio n , and
ve rtic a l gain. A sample o f the Channel 1 in p u t signal is also
p ro v id e d to the T rig g e r P ic k o ff and G enerator c ir c u it to
p ro v id e in te rn a l trig g e rin g fro m the Channel 1 signal o n ly .
Fig. 3-2 shows a d etailed b lo c k diagram o f th e Channel 1
In p u t A m p and Preamp c irc u its . A schem atic o f these
c irc u its is show n on diagram 1 at the rear o f th e m anual.
In p u t C oupling
In p u t signals applied to th e CH 1 c o n n e c to r can be AC-
c o u p le d , D C -coupled, o r in te rn a lly d isconnected. When
In p u t C o u p lin g sw itch S 8A is in the DC p o s itio n , th e in p u t
signal is co u p led d ire c tly to th e In p u t A tte n u a to r c irc u it. In
th e A C p o s itio n , th e in p u t signal passes th ro u g h c a p a c ito r
C8. T h is ca p a c ito r prevents th e DC c o m p o n e n t o f th e signal
fro m passing to th e a m p lifie r. When the G N D p u s h b u tto n is
pressed in , sw itch S8B opens th e signal path and the in p u t
to the a m p lifie r is connected to g ro u n d . T h is provides a
g ro u n d reference w ith o u t th e need to d isco n ne ct the
a p p lie d signal fro m th e CH 1 in p u t c o n n e c to r. Resistor R8
allow s C8 to be precharged so th e trace rem ains on screen
w h e n sw itch e d to A C c o u p lin g w ith a high DC level applied.
V a ria b le ca p a c ito r C9 adjusts th e basic in p u t tim e co n s ta n t
fo r a n o m in a l value o f one megohm X 24 picofarads.
In p u t A tte n u a to r
The e ffe c tiv e overall Channel 1 d e fle c tio n fa c to r o f the
43 4 is d e te rm in ed by th e CH 1 V O L T S /D IV s w itc h . In all
p o s itio n s o f th e CH 1 V O L T S /D IV sw itch above 5 m V , the
basic d e fle c tio n fa c to r o f the V e rtic a l D e fle c tio n System is
10 m illiv o lts per d iv is io n o f C R T d e fle c tio n . T o increase
th is basic d e fle c tio n fa c to r to th e values in d ica te d by the
V O L T S /D IV s w itc h , precision a tte n u a to rs are sw itch e d in to
th e c irc u it. In the 1, 2, 5, and 10 m V p o s itio n s , in p u t
a tte n u a tio n is n o t used. Instead, th e gain o f th e Preamp
3-3