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USEFUL INFORMATION FOR USERS OF TEKTRONIX INSTRUMENTS
NUMBER 24 PRINTED I N u . 5 . ~ F E B R U A R Y 1964
er, Accessory
Infrod~{cfion Tlie conventional current transformer with in the spnce between tlie inner and o u t e ~
Modern technology requires measurement 1;imin;~tetl core (Ref. 2) is useful up to contluctor of n coaxial transmission line
c a p a l ~ ~ l l t ~ Ini the f ~ a c t ~ o n a n.wosecond
c l a few kc. Tlie tape \vourid version extends of impedance Z, (Figure 1 ) . For simplic-
(lo-' second) a1 ex D ~ o d e s\T 1t1i sn ~tclimg tlie frequency response :md phase correla- ity only lialf of the IcngLh\vise section is
t~mes \\ell under 100 p ~ o s e c o n d s(lo-'' sec- tion to approsinlately 100 Icc. represented. The H (magnetic) field will
o n d ) :uid transistors n ~ t l if t (cut off ire- If the design of a current transformer terminate in a current sheath J in the eir-
quenc) ) of over 1000 Mc nl c presently a\ all- is based on a T E M (Transverse Electro- cular winding
able
Tlie s a m p l ~ n g oscilloscope prov~des ;In
magnetic Mode) approach however, the (Curl I l = + J since
excellent tool f o r tlie ol~servat~on these of
Insic f requcncy limitations are overcome b t
and fractional nanosecond speeds can be inside the Ivinding .'. curl H = J.)
phenomena provided the signals are pre- nchieved.
sented in a 5On characteristic impetl:mcc Also, since H is proportional to I, then
system. Ilowever, it is \cry seldom that $5 = I and a current I will flow in
one can load a circuit with 50 either in Tlzc TEjlI Czirrcjzt Trnusforii~er Z, for a single turn winding. A t X3 the
parallel or in series without disturbing it A single turn circular xitiding is inserted current I in the single turn winding will
beyond use. Therefore, one has to provide
means to extract the voltage and current
waveforms from the circuit ~vithout dis-
turbing the circuit to any great extent.
T h e output of this device should present, to
the sampling oscilloscope, an undistorted sig-
nal on a 50 n level.
I n tlie case of voltage measurements, a
good high frequency resistor (Ref. 1) map
be selected. Provided it is placed in a
proper environment, this type of series probe
will perform rather xvell up to 1000Mc.
F o r the current waveforms, however, the
solution is more complicated. Conventional
current monitoring devices are restricted
t o relatively low frequencies either by basic
limitations or b y strap parameters. For ex-
ample, the Hall potential in a Hall device
is established in approxitnately sec-
ond. Hoxvever, its inherent stray capacity
and flux-linliage patterns prohibits its eco- Figure 1 . A single-turn winding inserted in the space between the inner and outer conductor of
nomical use above a few Mc. a coaxial transmission line of impedance Zo.
T e k t r o n i x Instrument-Repair Facilities: There is a fully-equipped a n d properly-staffed Tektronix I n -
A-2205 strument Repair Station near you. Ask your Field Engineer about T e k t r o n i x Instrument-Repair facilities. 2/64
I-cgener;\te I 3 in e c l ~ l l ~xignitutlc :lilt1 :1c- \\'e have a trnnsiorrner \\.it11 one pri- 2 Z, c:il~le, a s shown. I-Io\vcvcr, this will
c o r t l i ~ i a to tlic principle o i super-positio~i m i r y : u ~ ln seco~itlary t u r i ~ s (Figure 2 ) . work only i o r a time ccluiv;~lent to tlic
I;= = r<, - IZ,. I i we introduce a cui-rent step I in the double tlel;iy time ( 2 T ) in one Z , c;\ljlc
primary \vintliiig, \ye will i~itroduce n cur- 1)ec;lusc niter t h t the gener;itor will he 1
rent step i,, at tlic s c i i i ~ c timc antl o i equal shorted. One c:ui extend this timc spati
m;\gniti~tlc in :\I1 n t u r i ~ s . T h e step i,, intro- 1jy placing an impetl;lnce in the short cir-
iiidic:ltiiig tli:lt tlie inipedmce Z I is ef- duced in a particular turn \\.ill propngatc cuit loop - here done by means of a fer-
fectively plnccd in series \\.it11 Z,,. (Tliere- iii n tr;~iismission-linc ~notlea r o u ~ x ltlie core rite core (Iiefs. 6 antl 7 ) .
f o r e , to iii;\int:li~i ;I iirst ostler m:ltching, in both tlirectioiis :11itl so \vill ;ill steps in
tlie ratio o i the tli;\ii~etcrsof tlie inner :md every turn. Tlie resulting output Jvave-
o u t e r contluctor plst S. in the S direction forms ;it tlie secondary terminnis of tlie
sliould 1)e reduced to I)e equal to Z?.) A sec- transforiiier will, therelore, look like Fig-
ond order c;qncii~ve reflectioii occurs bc- ure 3 indicating a "pusli-pull" mode oui-
cau5e tlie E field in going f r o m S1 to SJ
is confined l~ct\veen tlie inner conductor
anti tlie winding and betiveen the outer
c o ~ i d u c t o r2nd tlie winding.
Seglecting the winding transit time, for
a n "n" turn \\inding YJ = I \vodd still
6 b l d ; lionever, I \\.ill be a current I/n per
t u r n . Tlie current through Z1 is I/n antl
t h e series voltage drop reflected in the
I
11 - I
original E field is ---- - -
nZ
Therefore, Z? =
T
T h e reflected impedance is proportional
t o 1/n2, similar to the conventional trans- Figure 3. Output of twelve-turn transformer.
f o r m e r A true mathematical deriwtion of
these results amounts to a dolible hountlary put. Here, then, w e have tlie first basic
value probletu ( R e f . 3 and I ) and is quite limitation: tlie risetime of tlie output wave-
involvetl. I-Iowcver, this is not essential form will be approximately n times td,
t o achieve a basic understanding o i tlic where td is tlie delay of one ~vinding. Figure 5. Twelve-turn bifilor winding.
functionitig of a T E M transformer. Tlie second limitation of tlie conventional
U p to this point w e really have not current transformer is the fnct that there I n Figure 5, rather t1i:ln ~ v i n dan n turn
solved all basic limitntions of the tmns- is a certain :\mount of stray cap:lcitance single winding transformer, t\vo windings
i o r m e r , ) e t tlie prccetlmg is essential for (C,) antl inductance (Ia,). This will form
t h e untleritand~ng of the methods itivolved a distributed L-C circuit that ~vill resonate
I1
in solving them. each having turns have been wound
at a
0.33
frequency below - - (equivalent
- -
n s ttl
3-db point due to tlie first limitation) antl, bifilar, a s sho\vn. T h e four output volt-
therefore, give a poor transient response ages a r e then added and supply one single
especially ~ v h e n n is large. ended signal. Tlie addition is performed
n i t h tlic trans~nission line addition tecli-
nique. However, f o r practical reasons tlie
wires a r c kept very short and, therefore,
tlie double delay time (2T) is short. One
depends m:linly on the isolation provided
by ierrite beads placed in the short circuit
loop. Leads should be kept to the same
length t o assure time-coincident addition of
the signals. By doing this w e have acliie\wl
two improvements ( F i g u r e 6) :
Figure 4. A step V, placed simultaneously ( a ) T h e risetime of tlie output pulse, due
on two Z, cables, odds the two steps to a 2V to limitation one, has been reduced
step into a 22, cable. f r o m n s td to n/2 s td ( T h i s is not
exact because the turns in this case
In Figure 3, if a step V is placed simul- nil1 be sl~glitly longer; therefore, td
b b taneously on the two 2, cables, one can nil1 be sl~ghtlygreater. However, this
Figure 2. Twelve-turn transformer. add these t ~ v osteps t o a 2 V step into a effect is small.)
@ 1964 Tektronix, Inc.
A I, "!_L._ D^_^".,^-l
9 turn
trans-
ulser
tunnel 661
452
diode
5Tl
( 0 ) Pulse direct to 452. ( b ) Pulse coupled to 4S2 via o straight ( c ) Pulse coupled to 452 via 3 x 3-turn
nine-turn transformer on o 1/2" dia. transformer on a 1/2" dio. by ',&" core
by ',&I' core. [some core as used in ( b ) 1.
Figure 6. System used to obtain these waveform pictures: Tunnel diode pulser ( ~ 3psec risetime), Type 661 Sampling Oscilloscope with a Type 452
0
Dual-Trace Sampling Unit and a Type 5T1 Timing Unit, and a Type C-19 Camera. Sweep Time/cm: 0.2 nsec.
( b ) T h e transient response, due t o limita- Generally the low permeability ferrites
tion t ~ v o , Iias been improved due to have a Iiigli resistivity and the high perme-
the fact tliat the stray capacit;uice has ability icrrites a low resistivity. Tliereiore,
been reduced since the trvo windings the high permeability ferrites liave higher
at every point on the core move in tlic loss than the low permeability versions.
same manner volhge-\vise [ i r (reso- Some typical high frequency ferrite materi-
m n t irequcncy) proportional t o l / ,ic] als a r e :
while the inductatice and resistance stay
essentially the same. Periileabilifg R h o ( Q 2111)
Note that a t DC the two windings a r e in
Ferroscube 101 200-250 > 10"
102 250-100 400-600
series. Tlie output voltage is the same a s 101 300-700 250-150
that o i a conventional 11 turn transformer.
One cnn use niultiplc turns througll the iso- FERRITE Kearfott hfX30 4,000-6,000 300
bli\'60 5,000-10,000 230
Intion 1)eatls t o obtain a large time constant. BEADS
Kote also tliat one is not limited t o 2 rviiid-
ings of n/2 turns per I\-inding. One can T h e Design of a T E M Current Trans-
use n windings o i 1 turn per ~vinding (as f o1.111~~
long as n/a is greater than 1 and a real In order to design a Iiigli speed current
number). T h e liiiiitntion is 11 rvindinns of transformer, one Iias to consider several
1 turn per ivintling and there the risetime factors; transformer ratio, risetime, lo\v
is equivalent t o 1 s td o r the total prop:\- frequency time constant, space ava~lable,
gation titnc around tlie core, wliichever is impedance level, ctc. T h e lumped constant
greater (Figure 7 ) . equivalent circuit is represented in Figure 8.
One can i~uiltla t r m s f o r m e r \vitli :I large H e r e R, = R, n ? ; L = I-, n'
Figure 7. Eight-turn multifilor winding.
~ l u i n i ~ c r tusns to get n long time const:int,
of
but at the sntne time one c:r!i get a very
R, is assuiiiecl to be a constant propor-
o i the r\.iiiding. T o cxtend this lime usu:illy tional to tlic core losses and expressed in
iast risetime and good tr:insient responsc,
i o r higli frcquency :ipplicntic,iis n ferrite olims/turn2. I n practice, lio\vever, one might
ns \\-ill Ije esplai~letllater.
core m:iteri:\l (Ref. 5) is used. Fcrrites Iinve to use a tlifierent 13, i o r high fre-
a r e sinteretl innterials, generally of a l m i - quency (and lo\\- frequency) calculations de-
Core -1ftrterinl
cally spinel cryst:illinc structure consisting pending 011 material and bandrvitltli. Tlie
Unlcss a core rvitl~ a permc:il~ility >1 is o i I\IOFe20, n-liere Bf can be o i any of values given .1 the ferrite manuinctilrers
,
inserted inside tlie \\inclings, the tr:uisiornicr tlie follorving elements: Co, Xi, hIn, Cu, generally refer to the lorv-frequency losses
action is limited t o t h e double t r a l i s i ~time Mg, Zii, Cd. of the material. They liave no consistent
tinie constant since a t low frequencies the
turns appear in series. T h e transformer
may be used for current measuring purposes
a s well a s f o r tnatcliing t ~ v opoints of dif-
ferent impedance levels. I n either case, the
transmission line will have a voltage Ivave-
form a s well since tlie characteristic ini-
pedance is always greater than zero. I n
order to prevent capacitive coupling of tlie
voltage waveform, tlie transformer has to
be u d l shielded by a ground plane between
tlie center conductor and tlie transformer.
Figure 8. Lumped-constant equivalent circuit of a current transformer.
-4 perfect shield is not feasible, since tliis
\voultl amount to a shorted turn on the
correlation \\-it11 tlie frequency vnlucs of R,,. \\-ill he limited to a liiglier fl-ecluency. I t trnnsformer. However, satisfactory shield-
T h e r e f o r e , these need to 11e nie:isuretl for ing can practic:illy he :~cliieved by leaving
can he readily verified that :
individual materials. '\;alucs vary from 20 a narrow gap in tlie shield.
f2/n2 to > 500 Il/n2 depending on core ma-
t e r i a l and dimensions. References
Id,, is a constant proportional to tlie per-
Tlie phase shift \\.ill be :ipprosimately 1. C. N. \\'inningstad, I S A N D O U T O F
nie;kbility of tlie core, tlic cross section and
8.1" at tliis frequency. If :I m:lsitiium pli:~se C I R C U I T S \\'ITI-I P R O R E S , Proceed-
t h e magnetic length. F o r a cylindrical core
shift of lo is required tlie lo\ver frequency ings of the Xation:ll Electronic Con-
w i t h outer diameter D, inner diameter tl
response should be limited to a still liiglier Icrence; 1610, pp. 161, 1963
and length t, tlie intluct:mce/turn' can be
frequcncy. Ii?; performing tlie necessary
estimated b y : L , = 0.2 pt I n D/d s lo-" F. I<. I-Tarnis, EIdECTRICI\12 ME.-\S-
c:1lculntions one finds :
pH/n2 U R E M E S T S , \\rile,;, pp. 542-564
Z,,, = the transformed impedance.
Reitz - Milford, F O U Y D A T I O S S O F
T h e low f requcncy cut-of f is determined ELECTRO-MAGNETIC THEORY,
b y the L / R time constant. .-itldison \\'eslep, pp. 210-214
A s a practical example, n transformer
T h e re5ponse ~ v i l lbe 3-(111 do\\-n i f : \\-it11 a low frequency 3-db point of 10 kc Morse - Feslibach, M E T H O D S OF T H E -
w L = 2 x f L = R, where R is t l ~ e total \\-ill have n 1% amplitude accuracy above ORETICAL PHYSICS
resist:uice R,, in parallel \\-it11 L. 7 0 1 ~ and less than l o phase shift above
570 Iic. Polydoroff, HIGH-FREQUEXCY
nT,,RI,
R,, = M A G S E T I C X 4 T E R I A L S , \\'ilep
n'R,, + R,. F r o m the low frequency point of view it
C. K . \\'inningstad, SAXOSECOXD
is tlesirablc t o have a Inrge numl~erof turns
to m:~lie I, and R I 1:u.g~. A s previously PULSE TRASSFORNERS, IRE
sliolvn, this limits tlie risetime. Transactions on Kuclear Science, h/larch
A t tliis point there will he a 45" phase '59
Ii?; splitting the ~vinding into several
sliiit through the trnnsiornicr. multiiilar turns, as previomly outlined, one Lev% - \\'ells, M I T L I M I C R O S E C O N D
I f accuracy of 1% is required in tlie can maintain the risetime for high speed I'UL2SE T E C I H X I Q L E S , Pergamon
transfer ratio, the low frequency response operation and still have a large L and long Press
One solution to this problem is to use "Scope Pad" consists of twenty, trans-
:I slieet of "Scope Patl". This is a unique lucent, :ldlicsive-lxd;cd sliects ruled with a
product ni:liiuiacti~rctl :lnd tlistri1)utetl 1,y graticule-line g r i d .-\t tlie side of each
Eiisc:l, Inc., P . 0 . 130s 253, S e w YOI-li, slieet a r e spaces for tinie and amplitude
N e w York 10023. data.
If you \\-anted to malie a record of a
repetitive \v:~veform displayed on the crt
of an oscilloscope and you didn't have a
camera, you could stand 11:ick wit11 easel
;md pen, hold up your tliunib in Ren1br;lndt-
style and slietcli alvny. O r , >-ou could place
:I sheet of translucent pxper over the face
of tlie crt and trace tlie waveform. Tlie
difiiculty here, of course, is trying to hold
the p a p c ~ firmly in place and at the same
time n i d x the tracing.
SHORTING PROBLEMS DURING TROUBLE SHOOTING T Y P E 575 T R A N S I S T O R CURVE
TRACER - PEAK-VOLTS AUTO-
Cliucl< hliller of our Field Training group density (tightly-notched) ceralnic strips- TR.4SSFORlER IMPROYElIENT
calls our attention to a serious problem see Figure 1.
t h a t can exist wlien attempting to trouble- Here is a service that if performed on
shoot an instrument incornoratinrr Iiirrli- I f , in this trouble-shooting, the probe the Peak-Volts autotransformer (T701 in
employed uses a large tip-the old-style the collector-sweep schematic) will improve
double-pinclier tip for example-the danger its operation at low collector voltage wlien
exists of shorting out components and pos- the H O R I Z O N T A L V O L T S / D I V con-
sibly destroying expensive transistors, di- trol is set to the 0.01 collector-volts posi-
odes, etc. tion.
A way to minimize tliis problem is to Prior to tliis service the P E A K V O L T S
use the ne\ver and thinner pinclier tip (Tek- control will not turn down past around
tronix P a r t Number 013-071-see Figure 2 ) . 5 ctn of volts with the H O R I Z O N T A L
This blade-like, single-pinches tip offers a V O L T S / D I V control in the 0.01 position.
greater margin of safety against the sliort- a f t e r the service it will turn do\\n to 2
ing out of components in cro~vtlcd areas cm of volts and the oneration doum to and
and the improved pincher tip has greater up from this position will be very sn~ooth.
holding ability. The thin blade design causes The service consists of lo~veringthe mini-
a rnininiutn of component displacement dur- nlum voltage output of the autotransfortner,
ing trouble-shooting and facilitates cliecking T701. T o do tliis, loosen the screw liold-
dif ficult-to-re:~li test points. ing the rotational limit stops and adjust
tlie stops so that counter-clockwise rotation
This newer pinclier tip is designed to be can be made tlonn to the last one or two
used with the following Tektronix probes: windings. Care m t s t be exercised ?tot to
nllow file contact to rwz o f f the end of the
ecim/it~gs as damage could result.
Figure 1. These two ceramic strips are the
P6001 P6005 P6009 P6027
same length. The conventional strip ( 0 ) con-
- ..,
tains 9 notches. the hiah-densitv strio i b \ con-
tains 16 notches.
,
P6002
P6003
P6006
P6007
P6017
P6022
P6028
P L A S T I C L I G H T S H I E L D F O R REC-
T A N G U L A R CRT's
A plastic liglit sliield, similar to that
used in Tektronix instruments with 5"
round crt's, is available for Tektronix in-
struments with 5" rectangular crt's.
T h e shield is designed to block any
entrance of liglit onto the phosphor via
the space between the crt shield and the
front panel. Light escaping through this
space can prove botliersorne in some oscil-
loscope photography applications.
Designed specifically for the Type RM-
561, the sliield is equally useful in other
Tektronix instruments employing a rec-
tangular glass crt-the T ~ p e 567, Type
RM567, T ~ p e527, Type R X 2 7 and the
Type 561.4 110D210C or 210E. This sliield
is not needed nit11 the ceramc crt since
light is shielded by the ceramic envelope
and rubber boot.
Tektronix part numl~er of tlie ne\v liglit
shield is 337-586. Order through l o u r local
Figure 2. A comparison of the older double-pincher tip (left1 and the new thin-blade, single- Tektronix Field Office or l o u r Tektronix
pincher tip ( r i g h t ) . Both shown with pincher extended. Field Engineer.
(2) 6-32 ALUMINUM SPACER
Breakage of the 3-ivire p o ~ v e r connector
KEPS NUTS SUB PANEL 4
1
o n instrunients employing a t1etach:iblc 3- 1 I/ i
conductor power cord can occur \vlien the
i n s t r u n ~ e n t s a r e tilted o r liitcd from the
f r o n t with the p o ~ v e r cord connected.
T h i s breakage c:m be prevented by re-
cessing tlie po\ver connector a s slio~vn in
F i g u r e 3.
P a r t s needed :
Qtr Item Tektronix
P a r t No.
1 alu~ninutiispacer 361-012
2 l g " , 6-32 screw 211-545
2 6-32 Keps nut 210-457
Fig. 3 . Pictured instructions for recessing the 3-wire connector on instruments using a detachable,
3-conductor power cord.
T Y P E 527 4 S D T Y P E R X 2 7 \ \ . X \ T F O R I \ I 1IOSITOR-VOLT-IGE
S T R E S S O S 6E\\i6 T U B E S LIURIKG T U R K - O N
\4'1ien the Type 527 o r Type Rh4527 I i there is no appreciable change in hook Type RM527:
1Vavciorm Monitor is first turned on, 1 7 3 1 1 o r tilt, V111 and V54-4 a r e prolx~hly all
a n d 1'5% (6E\\.6 t u l m in the txvo-stage, right and the difficulty is most likely in the 730 tlirougli 732 1066
push-pull input amplifier) a r e subjected to tr;~nsmittetlsignal. 889 1071 tl~rougli1074
quite a voltage stress. This stress can c:iuse Type 577's wit11 serial nunibers above
908 1097
e s c e s s i w c;~tliotle tlcterioration \vliicli, in ill ;mtl Type RM527's with s e r i d numbers
t u r n , Ivill cause the tube to become gassy. :111ove 1189 li:~ve this modification installed 980 1116
U n d e r tliis condition the input amplifier :it the factory. Also, the follo\\;ing serially 997 1121
will not perform properly and the 6E\\'6 numbered instruments were niodiiied out lOz0 1122
t u l m in tlie input an?plifier a r e doonled of sequence :
t o early failure. 1035 1138 through 1141
Type 2 7 :
A siinple modification to overcome tliis 1036 1143 through 1145
615 724 tlirougli 726
prohlem consists of replacing the 0.01 @f/ 1147 tlirougli 1159
616 739 1038
47 1i R C net\vorli in the grid circuit o i both
674 1042 1162 tlirough 1188
V W and 1'5.13 \vitli a 153605 diode (Teli-
t r o n i s P a r t S u m b c r 152-141)-See Figure
4. A i t e r the modification, R4-40, 47 ohmthe
parasitic resistor will connect directly from
t h e re:ir \\.afer of the R E S P O S S E switcli
t o pin 1 of 1:W and tlie new diode will
connect between pin 1 and 2 of V W , Be
s u r e the cntliotle of the diode connects to
pin 2. Repeat these clianges in tlie grid
circuit of V 5 l l and the tiiodification is
complete.
Gassy 6E\\.6 t u l m in the 1-W and 1'54-4
positions c:iusc Iiooli and tilt in tlie dis-
played \vnvcform. This mnlfunction is most
:ipp:ircnt \vlien vic\vi~igthe vertical blanl pulse portion of the trnnsmitled composite-
video signal. T o determine nhether the
fault is in tire tr:insniitted signal o r in the
\Vaveform llonitor, positioii the vertical-
blanking-pulse \vaveforni near either tlie
top o r bottom of the crt. This iticreascs
the current througli either 1 1 1 r 1754-4,
7 1o
:inti i i thcy :ire gassy the hooli and tilt Figure 4 . "Before" and "After" schematic for replacing the 0 . 0 1 p f / 4 7 k RC network, in the grid
\\-ill be much mol-e pronouncetl. circuit of both V 4 4 4 and V544, with I N 3 6 0 5 diodes.
USED lNSTRUMENTS FOR SALE used Dalmo Victor, Eelmont, C:ilifornia, 1 T y p e 513D Osrilloicope, s/n 691. P r i c e :
r2ttcntion : I i r . \\'ells $4.50. Donald Flcischer, 503 Tennis .4venuc,
1 Type 513D Oscilloscope, s/n 1672 with
.-2ml1ler, Peniisy1vani;l. Tcleplioiic : hi1 6-
new CI-t. l i a y Case, 8146 LIatilija, Panorxma
1 Type 532 Oscilloscope, s/n 5100; 1 Type 0580.
City, Californi:t, phone 780-0322. Price :
$350. 53G Plug-111 Unit, s/n 100 antl 1 cart. M r .
Ricliartlson, N. J.E. Corporation, 20 Boright 1 Type 502 XiOD104 Oscilloscope, s/n
1 Type 317 Oscilloscopc, s/n 346. In- .%venue, Iicnil\vortii, Ken7 Jersey. 2840. D r . I'cclcll;t~ii, Eye Research Founda-
strumcnt like iiew. \\'ill sacriiice f o r $500. tion, 8710 Old Georgeto\vn Roatl, Betliesda,
M r . Rising, 53 Hundreds Circle, \\~cllesley 1 Typc 67 Plug-111 Unit, s/n 2596. ;\'ever M:irylnid Plione : 301-656-1527.
Hills, Nassachusetts. Telephone : :\re;\ Code used. I n original paclii~ig. Mr. Leo Iiatz,
617, 235-0385. Electronics Laboratory. S o t r e I h n e 1-10s- USED INSTRUMENTS WANTED
pita], 1560 Slierbroolic Street East, hIon-
1 T y p e 535 Oscilloscopc, s/ii 6095 with a trcnl 24, Quebec, C:lnad;i. Telephone 525- 1 Type 310 Oscilloscope. E. C. \\-ebb,
T y p e 53/54C Plug-In Unit, s/n 9668. P r i c e : 6363 --Local 576. I-ake\vood XIanui;lcturing, 25100 Detroit,
$1200. R. L. Bennett, T o d d - A 0 Corporn- \\'estlalie, Ohio. Tele~)lioiie Area 216-
:
tion, 1021 Se\v;trd Street, Holl!~\vootl, Cali- 1 Type 190.4, s/n 6048; :md 1 Type 190I3, TR1-5000.
fornia. P h o n e : H O 3-1136. s/n 69.52 Const:int-Amplitude Sign:il Gen-
erators. A. S:uuuelson, Electric Service Sys- 1 Typc 321 Oscillosco~x, John Sumner,
1 Type 511-4D Oscilloscope, s/n 4718 with tems, 5555 Old I-Iigh~vay 5, Riiilnc:ipolis 728 N. Sa\vtelle, Tucson, -4rizon:~
P5lO -4ttenuntor Probe. Reccii~ly rep:~ired,
24, Mi~uiesota. Telephone : 941 -2200.
modified ;lnd recali11r:itetl at Tcktronis Re-
1 Type 515 o r T l p e 51.5.4 Oscilloscope.
pair Center. R. J. Fr:uicc, Control Science
1 Type 517, s/n -508, High Speed Oscillo- \\'illiam II:~cougl-itry, Code 536, K A S X ,
Corporation, 5150 Duke Street, ."iesandri:l,
scope. F o r sale, I e x e o r rent. Recently Godtl:lrtl Space Flight Center, Greenbelt,
\7irgi~iia.
overhauled by Tektronis, Inc. Micli;lel J. II;irylnnd.
1 Type 502 Oscilloscopc, s/n 4211 :inti 2 H:~ltl:ltl, S u r f x c - A i r Electronics, 138 Kc-
Type 122 Preamplifiers, s/n's 5494 antl 5495. \~ntl:t Street, E l Scgu~itlo,C:lliiornia. Telc- 1 Type 524AI3 Oscilloscope. 1-1. Holland,
Instru~nents I ~ a v e seen little use. C. R . ~ l l ~ o i iSI'2-1469.
e 1-1. \\'. 13. Electronic Sei-vice, 7217 Gulf
Smith, President, Capital Sales Ltd., P. 0 . Boulevard, St. Petersburg Dench, Florida.
Box 266, Fredericton, S e w Brunswiclc. 1 Type 82 Plug-In ['nit, s/n 2307. Joel
Gaclcer, M:ignetic Revxrcll Corporation, 1 T l p c 310, 316 o r 515 Oscilloscope. $225
1 Type 81 Plug-In .Ad:ipter ( f o r use n-it11 3160 \\'cst El Segundo Boule\.;ircl, I-Ian- m:isinium George Reevci, 3273 \\.. Oal,
Type 580 Series Oscilloscopes). New, never tliorne, California Telephone. O S 5-1171. Avenue, Fullerton, California
M r . John Eowser of the Smith Corona this instrument shoultl he relayed to Mr.
Corporation a t 301 5 . hIicliigan St)-eet, 0 . Sic1;crson o i the Ge11cr:il Electric Com-
Chicago, Illinois, reports (lie thcft of :I T!yc pany a t the address noted al~ove.
310.1 Oscilloscopc, s/n 17926. T h e instru-
ment tlis:ippenretl from the car of one of
their servicenxn \vIiile it was parlml in the This last report of a missing instrument
back of tllcir office building. M r . Gonser concerns one that dis;tppc:1red on Janu;lry 1,
\voultl appreciate hearing from any of our 1963 ant1 Ii:ls just been called to our at-
readers \\-I10 have :my information on the tention.
\vhereal~outs of this instrument. This oscilloscope, a Type 310.-1, s/n
012960, l~elongs to I-Iuycl; Systems located
on \\.oli Hill Roatl in I-Iuntington, Long
Another car prowl, this one :ilso in Clii- Island, S e w Yoi-k.
cago, protlucctl a Type 516 M O D 108PJ M r . A1 Richcrt of I-Iuyck Systenis tells
f o r tlic ~intl:ils. Serial nunilxr of this in- u s t11:1t the oscilloscope \\.;IS :it T.ocl;l~eed
strument is 1930 antl it is the property of in Eurl~:l~il;, Ctliiornia a t the time of its
the Gencr:~l Electric Company, 840 S. dis:~ppe:~r;c~iccand he asks our renders in
Can:ll Str-ect, Chicago, Illinois. T h e thcft that :\re;\ to he on the l o o k o ~ ~ t r it.
fo
occurred on Tucstl:ty, Novemlxr 26, 1963, XIS. Richest is the nmn to contact if you
while the car \vas parked outside their h v e any inforniatioii nbout this oscillo-
building. Information on the location of scope.
\vidtli of the test pulsc is ninde to be one- ijiic pulse of the received sign:il. Tlie
h a l f of the period of one cycle of the
u p p e r ciltofi frequency of tlie T I y systcni.
T h u s t l ~ e pulse \vitlth \vlien used u.it11 n
4 megacycle systeiii is 0.125 iiiicrosecontl.
T h i s time (0.125 psec) is designated by
:I capital T . --I sin' pulse \\-it11 a \vitltli
of 0.125 psec is 6 db down at 4 megacycles
a n d contains practically zero energy at 8
niegncycles. F o r routine tes.ts :i sin' pulse
~ v i t h :i width o i 2 T (0.2.50psec) c;ui Ix
used. A sin' T pulse is slionn in Figure 3.
T h e sin' l n r , also called :i \vliite n.ii1-
(low, is :I coml~iiintion o i :I squ;i~-e-\v:cve
:ind a sin' pulse. Tlie risetinie :11it1 fall-
tinw is the same :is :in i11tegr:itetl sin'
pulse n.liile the il:it-top is similar to ;i
scluxre-\vave. l'ulse width o i the bar sig-
nal is 23 ~iiicrosecontls~vliicli is 0.4 13. ( I i
cation of tlic kind of distortion a system
protluces. H e r e a r e several examples of
tliese chaiiges.
1. Low-f requency distortion. This type
of tlistortio~l has its greatest effect on
tlie sin2 bar \vhile little change is seen
in the sin' pulse. Dcpenditig on tlie time-
constzuit of tlic circuit involved, the bar
will slio\v : untlerslioot, overshoot, or
horizontal tilt. F o r example, a sliort time-
constant unciershoot is a leading-edge roll-
o f f , as sho\vn in Figure 6-a ; wliilc a long
time-constant overshoot is a negative
Figure 4. Sin2 bar, a combination of a sin' pulse and a square wave.
tilt (drop in atnplitude f r o m le:iding
to trailing edge), a s shown in Figure
6-b.
s i n 2 pulse s i n 2 bar
\ I
I-
psec
Figure 5 . Composite test signal with typical time spacings.
signal is present only on a single line o i
e:lcl1 fs:iiiie, some tnetliotl o l selectiiifi :ind Figure 6. Sin2 test signal showing: ( a ) short
Tlic type o i oscilloscope needed to e ~ - cs:uiiiniiig rliis line must he used. Tlie time constant undershoot, ( b ) long
time constant overshoot.
xiiiinc tlic sine-squ:ire s i y d tlepentls on liiie selector icnture o i the Tektroniz
Special--\Iotlel Type 527 o r Type RX1.527 2. FI-equency riesponse irl-egul:~rities.
:illo\vs the operator to select :ind es:umine \\lien the irequency response is not
generator supplies the test sigii:~l c o n t i ~ ~ u - :illy line \vitl~in the television fl-:me. I ~ I - i e i - il:it :icross the l)a~itl\vidtIiof the system,
o u s l ~ .:i triggered oscillosco~)e sucl; :is tlie Iy, the line selector uses tlie ~)rinciple \\.e get dips ;uld l ) i i m ~ ~ sThese clips and
.
Te1;tronis Type 524 nit11 :ltljust:il)le time- of a de1:cyetl trigger. A 11-igger circuit buiiips on tlie test signal a r e actually
Inse can be used. I-lo\vevei-. \vilen tile test pliantastron is started by the vertical ringing 111:it is related t o the irequency
@ 1964 Tektronix, Inc.
All Riqhts Reserved
Figure 7. Sinz test signal with dips and bumps Figure 8. Sin2 pulse showing a leading and a Figure 9. Sin' pulse showing distortion caused
caused by frequency response irregu- trailing reflection or echo. b y high frequency roll off: reduced
larities. height, increased width, and decay-
ing ringing.
hy Ron Bell
Tektsonis Field Engineer
Figure 1 . Power-line waveform with simulated
transients.
T o differentiate l)et\l-een t r m 4 e n t volt-
Pliotogr;~phing transient \
i would be rel- ages and the power-line waveform, t h e
+225 +225 +I0 0
TRIGGERING AC LF
4.7k 47k
MODE REJECT
To trigger m v TRIGGER SLOPE + Int
,001
- 6DJ8 -
Connect the Calilx:ltor output to the plug-
150k in iiiput. Starting \vitli the Trig. Level
Centering Coiitrol tur~iecl lully clocl~wise,
turn it counter-cloclavise for a display
47
39 k
LEVEL
22 k
Switch functions not
shown for simplicity.
- 150 - 150
Figure 2. Modified Trigger-Amplifier Circuit of a Type 530 or Type 540 Series Oscilloscope.
Figure 3. Initial display during adjustment pro-
T h e niotliiietl-circuit diagram is sIio\vn in
-.
I rigger sctisitivity of tlie modified cir- cedure. The vertical deflection factor is 1 volt/
cm. The s w e e p rate is 2 psec/cm.
F i g u r e 2. Notice t h t tlie only :itltlitionnl cuit is less tlinn normal. Unii~otliiied, the
p r t s required a1-e t\vo T-12G diotlcs, a triggering ciscuit \\rill respond to 0.1 volts
150 k resistor and :I 47 1i resislor. Notice o r Icss. This circuit requires :~pprosimatcly
a l s o tIi:tt the 47 pf capacitor normally con- 1.5 volts. F o r simplicity, the riglit-1i:cntl
similar to Figure 3. S e s t , rctlucc the ver-
nected :icross the plntc-lo:itl resistor of tlie triotle gritl is grountletl. I?ec;iuse of i n -
tical tleilection \vith the \-olts/CZ\.I controls
left-li:incl triode 11:s been removed :ind that 1):d:ince in the triodes ;mtl tolerance in the
until either the upper o r lower trace dis-
tlie gritl o i the riglit-1i:ind triotle is grountl- plate-load resistors, it is titilikely tli:it the
nppc:irs. Turii the Trig. I m d Centering
ed. plate volt:iges n.ill he c c p l . T o avoid the
Control CC\\' to restore the tlispl:iy. Con-
possilility of no-signal diotle conduction,
tinue to reduce the vertical tleflection while
Circuit operatio~i is alniost self-espl:in:~- tlic diode :inode \.olt:~ges :ire I o n w t1i;in
:itljusting thc Trigger I.cvel Centering Con-
to]-y. T h e t\vo T12G diotles are nor~ii:illy ~ ~ c c c s s : ~ r This means the triggering volt-
y.
trol until tlic two 11-:ices a r c separated by
bacli-l~i:~sctlI>ct\veen the center-tap of tlie age ~ u u s t overcome this lxicl;-l~ias hefore
1 cni or Icss.
volt:tge divider and the quiescent triotlc triggering c:tn occur. Tliis should not 11e
plate voltages. T h e sisty-cycle polwr-line ;t Ii;\ntlic:\p, lio\vcver, sitice :imple trigger-
w:lveform (:ind, of course, tlie tr:lnsient) ing voltages a r e usually nvailable in polvcr- T o w r i i y your adjustments, connect the
is connected to the input connector. line testing. c:dil)r:itor output to tlie External Trigger
Input coiinector. Set tlic Trigger Slope
T h e time constant of tlic I00 p i coupling Scar-rios~ii:il serisitivities can he realized Switcll to + E s t . You slioultl IIC able to
cxpncitor :tnd the 100I< input resistor is I)!. repl:iciiig the 1.50 l i ~sesistorin tlie divider oht;iin displays siiiiilar to Figure 3 over a
short enough to effectively I~locktlie sixty- \vitli :I 2 2 0 1 ~resistor. It \\.ill I)e iicccss:iry raiige of input voltnges i r o ~ i i2 to 10 volts.
cycle co~iipoinent; \vliile :it the same time, to check the 11l:ite vo1t:iges for iniInl:mce.
alloning fast-c11:mging tr:uisient volt;tges t o Removing tlie ground {I-om tile I-iglit-1i:uid I M n i l s on ho\v this modiiic:ition tiiigl~t
pass through t o the input gritl. T h e t\vo triotle grid \vill per~iiit using tlle TIITG- he i~istalletl in :in oscilloscope :me k i t to
triodes :\re operating as a pnr:ipliasc in- G E I I I S G I , I ~ \ T L control to achieve per- tlie inventiveness of tlic re:itler. Certainly,
verter. If tlic input trmsieiit is positive- fect 11:tl;ince. Of course, the opcrntor must consitler;ition should be given to ho\v fre-
going, it \vill cause tlic left-l1:ind plate Ile careful not to tlisturh this control once quently it ~iiiglitbe used. In those situations
voltage to go tlo~vn. Similarly, if the input :itljusted. \vInerc this tiiotle o i operation \vould be
transient is 11cg:ttive-going, it \\.ill c : m e the used often, :i permanent s\vitcli function
riglit-1i:uitl plate to go down. T o :idjust the circuits i o r correct oper- \voultl seem most convenient. On tlie other
:ition, set t l ~ e iront-p:mel coiitrols ns lol- li:uid, for occasion:il "one-shot" applications,
A negative-going voltage on either triode 1on.s : it might he simpler to "tncli-in" tlie conipo-
plate will c:iuse the associated diode to go ncnts :is needetl. On tlnose instru~iicnts1i:iv-
into contlt~ctiun. \ \ l ~ e n one of the diodes ing zun operator's manual conip:~rtment in
conducts, a neg:itive-going volt:ige :~ppcars the riglit-