Tektronix CA PLUG-IN User manual

I NSTRUCTION
I V I A I M U / M -
Tektronix, Inc.
S.W . M illikan W ay • P. O . Box 500 • Beaverton, O regon • Phone Ml 4-016 1 • C able s: Tektronix
Tektronix International A .G .
Terrasse nw eg 1A • Z u g, Sw itze rland • PH. 0 4 2 -4 9 1 9 2 • C a b le : Tek intag, Zu g Sw itzerland • Telex 53 .5 74
-|o2 _h '] 2.
070-318

WARRANTY
All Tektronix instruments are warranted
against defective materials and workman-
ship for one year, Tektronix transformers,
manufactured in our own plant, are war
ranted for the life of the instrument.
Any questions with respect to the war-
ranty mentioned above should be taken up
with your Tektronix Field Engineer.
Tektronix repair and replacement-part
Service is geared directly to the field, there-
fore all requests for repairs and replace-
ment parts should be directed to the Tek
tronix Field Office or Representative in your
area. This procedure will assure you the
fastest possible Service. Please include the
instrument Type and Serial number with all
requests for parts or Service.
Specifications and price change Priv
ileges reserved.
New material Copyright © 1961 by Tek
tronix, Inc., Beaverton, Oregon. Printed in
the United States of America. All rights
reserved. Contents of this publication may
not be reproduced in any form without
permission of the Copyright owner.

CO N TENTS
Warranty
Section 1 Characteristics
Section 2 Operating Instructions
Section 3 Circuit Description
Section 4 Maintenance
Section 5 Calibration
Section 6 Accessories
Section 7 Parts List and Schematic Diagrams

XAUBRATED
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TEKTRONIX, INC.
PORTLAND, OREGON, U.S.A.
SERIAL
Type CA AA

GENERAL
The Type CA Unit contains two identical
am plifier channels that can be electronically
switched either by the oscilloscope sweep or at
a free-running rate of approximately 100 kc.
When amplifier Switching is accomplished by
the oscilloscope sweep, the two Signals to be
compared appear on altemate sweeps. Because
the sweeps are identical, and time-delay char-
acteristics of the two amplifier channels are
closely controlled, time comparisons accurate
within 1 nsec can be made.
Either amplifier channel can be used separately
without electronic switching, making the Type
AM PLIFIER TRANSIENT RESPONSE
Risetime Passband
With
Instrument
Type
INPUT
SELECTOR
switch
in any
Position
INPUT
SELECTOR
switch in
either DC
Position
INPUT
SELECTOR
switch in
either AC
Position
541/541A,
545/545A,
555,581,
585 15nsec DC to 24 Mc
2 cps to 24 Mc
.2 cps to 22 Mc
with P6000 or
P6017 Probe
551
16 nsec DC to 22 Mc
2 cps to 22 Mc
.2 cps to 22 Mc
with P6000 or
P6017 Probe
531/531A,
533/533A,
535/535A 23nsec DC to 15 Mc
2 cps to 10 Mc
.2 cps to 10 Mc
with P6000 or
P6017 Probe.
536
35nsec DC to 10 Mc
2 cps to 10 Mc
.2 cps to 5 Mc
with P6000 or
P6017 Probe.
532
70nsec DC to 5 Mc
2 cps to 10 Mc
.2 cps to 5 Mc
with P6000 or
P6017 Probe.
AA Characteristics - Type CA 1-1

C A also useful ln all single-trace applications
within its frequency-response and sensitivity
capabilities. Maximum flexibility is obtainedby
providing separate positioning, sensitivity, and
polarity-inverting Controls for each channel.
Operating Modes
Channel A only.
Channel B only.
CHOPPED (Electronic switching at 100 kc.)
ALTERNA TE (Electronic switching on alternate
sweeps.)
ADDED ALG EBRAICALLY (Both channels com-
bined at output (A + o r- B)
Amplifier Sensitivity
Basic deflection factor--.05 v/cm, ac or de.
Nine calibrated sensitivities--.05 v/cm to 20
v/cm, accurate within 3% when set on any one
Step.
Input Impedance
Plug-in alone 1 megohm shunted by 20 pf.
10 megohms at 14 pf with P6000 or P6017
probe.
P410 probe with plug-in will be 10 megohms at
7.5 pf.
Physical Characteristics
Construction--Aluminum alloy Chassis.
Finish--Photo-etched anodized panel.
Weight--4 1/2 lbs.
Accessories
2-Instruction Manuals.
AA1
1-2 Characteristics - Type CA

O I M 2
OPERAT1NG
IN S TR U C T IO N S
Plug the unit into a Tektronix convertible
Oscilloscope and turn the power on. Allow
the instrument to reach operating temperature,
about 2 to 3 minutes and free-run the sweep
at 1 millisecond/cm, Turn the MODE switch
to A ONLY and the A-channel PO LARITY and
AC-DC switches to NORMAL and DC respect-
ively. Position the trace to about +2 cm with
the A-channel VERTICAL POSITION control.
Turn the MODE switch to B ONLY and the
B-channel PO LARITY and AC-DC switches
to NORMAL and DC respectively. Position the
trace to about -2 cm with the B-channel VER
TIC A L POSITION control.
Now turn the MODE switch to CHOPPED.
Two traces will appear on the crt screen.
Notice that the A-channel VERTICAL POSITION
control moves the upper trace and the B-
channel VERTICAL POSITION control moves the
lower trace. Increase the sweep speed to 100
microsecond/cm and notice that each trace
is composed of many start-duration elements.
The two channels are being switched at approx-
imately 100 kc so that each channel conducts
for about 5psec and then is cut off while the
other channel conducts for an equal time.
Now turn the MODE switch to the ALTERNATE
Position. There are still two traces on the crt
screen but the traces are no longer chopped
into small bits. For each sweep cycleonechan
nel is conducting and the other is cut off.
The channels are switched at the end of each
sweep cycle.
Note
Either of the two identical amp-
filied channels can be used in-
dependently by turning the MODE
switch to A ONLY or B ONLY
and connecting the Signal to be
observed to the appropriate input.
The following remarks apply equally
well to either amplifier channel.
PROBE CHARACTERISTICS
PROBE
TYPE
COLOR
CODE
AT TENU A
TION
RATIO
INPUT IM PEDANCE INSERTION
LÖSS AT
30 mc (db)
VOLTAGE
RATING
(Peak-to-Peak)
Resistance
(megohms)
TvDical Capacitance
Minimum* Maximum**
P410 Brown
nose
10:1 10 8pf
12pf+
llp f
15pf +
1600
P510 Black
Nose
10:1 10 14pf 1600
P6000 None 10:1 10 11.5pf 14.5pf 1.2 600
P6017 None 10:1 10 12.5pf 12.5pf 1600
*When connected to instruments having 20 ßßi capacitance (input).
**When connected to instruments with input capacitance up to 50 ppf.
f With 8-foot cable.
AA Operating Instructions - Type CA 2-1

Probe Adjustment
An adjustable capacitor compensates for slight
variations in input capacitance from one I n 
strument to another. This capacitor is located
in the probe body in the P510, P410( and in
the termination block at the instrument end
of the cable in the P6017. It takes only a
few seconds to check this adjustment, and it
is a good practice to make this check each
time the probe is to be used. Simply touch
the probe to the oscilloscope calibrator-output
terminal and observe the calibrator waveform
on the screen. If necessary, adjust thetrim mer
for a flat top on the calibrator square wave.
To adjust the Type P6000 probe, touch the
probe tip to the calibrator output connector
and display several cycles of the calibrator
waveform. If the top and bottom of the dis-
played waveform is not flat, loosen the locking
ring by turning it in a counterclockwise direc-
tion. Rotate the barrel of the probe as neces
sary to compensate the probe. Tighten the lock
ing ring carefully after compensating the probe,
being careful not to disturb the probe adjustment.
Input Coupling
It is sometimes undesirable to display the de
level of the waveform being observed. Placing
the AC-DC switch in the AC Position inserts
a capacitor in series with the input so the
de component of the waveform is blocked
and only the ac component is displayed. The
low-frequency response is about 2 eps when ac
coupling is used.
Output Polarity
It w ill be desirable to invert the displayed
waveform at times, particularly when using
the dual-trace feature of the Type CA. The
PO LAR ITY switch has two positions. In the
NORMAL position the displayed waveform will
have the same polarity as the input Signal.
In the INVERTED position the displayed wave
form will be tumed upside down; that is, a
positive-going pulse will be displayed as a
negative going pulse.
DC Balance Adjustment
After the plug-in unit has been in use for
a period of time you will notice that the trace
w ill change position as the VARIABLE control
is rotated. This is caused by tube aging and
the resultant shift in operating potentials. To
correct this condition see Calibration Section.
Gain Adjustment
Aging of the tubes will also affect the gain
of the plug-in unit. See Calibration Section
for this adjustment.
Positioning Adjustment
The Vert Pos Range control balances the de
output level so the full ränge of the front-
panel positioning Controls can be utilized. See
Calibration Section for this adjustment.
Types of Operation
Generally, three types of Operation will be per-
formed using the Type CA ünit; ALTERN ATE,
C HOPP ED, and ADDED ALGEBRAICALLY. The
three types of Operation are fundamentally
different so we will examine them in the order
stated.
ALTERNATE
Connect the two Signals to be compared to
the two Signal inputs and turn the MODE switch
to A ONLY. Set the sweep up for triggered
Operation and adjust the VOLTS/CM and VER-
TIC AL POSITION Controls as necessary to
display the waveform. Turn the MODE switch to
B ONLY and adjust the corresponding Controls
as necessary to display the other waveform.
Now tum the MODE switch to ALTERNATE.
If necessary, touch up the oscilloscope's sweep
triggering Controls to obtain a stable image.
Both waveforms will now be displayed on the
ert screen. As the control of each amplifier
is independent you can position, attenuate, or
invert the Signals as necessary to compare
their shape, relative amplitudes, etc.
Use the AC LF REJECT triggering mode
and ALTERNATE sweeps for INTernal trig 
gering on Signals having components above
10 kc. For lower-frequency Signals, use the
AC triggering mode. In the AC LF REJECT
Position, an rc filter is inserted into the Cir
cuit allowing it to recover quickly from the
de level changes encountered with the ALTE R
NATE sweep. To compare the phase difference
between two Signals, you should trigger
externally using the reference Signals as the
trigger Signal.
2-2 Operating Instructions - Type CA AA

VOLTS/CM -- Provides
calibrated vertical
deflection factors from
.05 to 20 volts/cm when
variable is in calibrated
Position.
VARIABLE -- Provides
continuously variable
vertical deflection
factors.
DC-AC -- Determines
whether input to plug-
in is DC or AC coupled.
MODE--A five Position
switch to allow either
amplifier to be used
independently, to pro-
vide for switching the
two amplifiers at an
arbitrary rate, to syn-
chronize the Switching
with the oscilloscope's
sweep, or to provide
fo r adding the: Outputs
of the amplifiers
algebraically.
POLAR1TY -- Deter
mines whether the dis-
. played Signal will be
in-phase or out-of-
phase with the input
Signal.
DC BAL -- A screw-
driver control to adjust
, the amplifier balance
' so the trace doesn't shift
as the VARIABLE con
trol is rotated.
VERTICAL POSITION-
Used to Position the
trace vertically on the
oscilloscope’s screen.
GA1N ADJ--A screw-
driver control used for
setting the gain of the
plug-in, thereby setting
the accuracy of the
VOLTS/CM switch.
F ig . 2-1. Functions of the Type C A fron t panel Controls.
AA Operating Instructions - Type CA 2-3

CHOPPED Note
When it is necessary to observe a single
transient at two parts of a Circuit another
procedure must be followed. In the foregoing
cases one of the Signals triggers the sweep
and that amplifier remains conducting for the
sweep duration. At the end of the sweep the
amplifiers are switched and the other Signal
then triggers the sweep and that amplifier
remains conducting for the sweep duration.
Each of the Signals is being displayed every
other sweep cycle. If you attempted to observe
a single transient in this manner the transient
w ill pass through whichever amplifier happens
to be conducting and will trigger the sweep.
This w ill display the transient as seen by
whichever amplifier is conducting but when
the amplifiers are switched at the end of that
sweep there will be no further Signal to trigger
another sweep until the next transient occurs.
The problem here is to be able to observe
the transient using both amplifiers during a
single sweep cycle.
Turn the MODE switch to CHOPPED. Now
the two amplifiers are being switched on and
off independently of any Signal. The switching
rate is approximately 100 kc so each amp
lifie r is conducting for about 5 jusec and then
is cut off while the other am plifier conducts
for an equal length of time.
It will usually be very difficult if not
impossible to trigger the sweep internally from
the Signal so the triggering Controls should
be set for external triggering. The external
triggering Signal should bear a definite time
relationship to the displayed Signals.
It is possible that the displayed
waveform could end up being the
100 kc switching waveform. This
is possible particularly if the two
traces are positioned very far apart.
The two Signals to be observed will be con
nected to the two inputs and both waveforms
w ill be displayed during one sweep cycle. Tran-
sients as short as 1 msec duration can be
well delineated, with about 100 elements in
each trace. As before, the independent control
of each amplifier will allow you to position,
attenuate, or invert the waveforms so they
can be easily compared.
ADDED ALGEBRAICALLY
In many applications s the desired Signal is
superimposed on an undesired Signal such as
line frequency hum, etc. The Algebraic Output
of the Type CA unit (with the MODE switch
in the ADDED ALGEBRAICALLY position)
makes it possible in many cases to improve the
ratio of desired to undesired Signal. Connect
one input to a source containing both the
desired and undesired Signal. Connect the
remaining input to a source containing only
the undesired Signal. Place the MODE switch
in the ADDED ALGEBRICALLY position. Set
the PO LAR ITY switches to opposite polarities
(depending upon the polarity of the desired
Signal). By careful adjustment, especially at
low frequencies, of the VARIABLE Controls
and/or the GAIN ADJ. Controls the amplitude
of the undesired Signal displayed can be reduced
by a factor of 20 compared to the amplitude
of the desired Signal.
2-4 Operating Instructions - Type CA AA

AMPLIFIERS
The Type CA Plug-In Unit consists of two
identical amplifier channels and a channel-
switching multivibrator. The followingdescrip-
tion of the amplifiers applies equally well to
either channel.
Input Coupling and Attenuation
The Signal to be displayed is applied to the
input cathode follower V3323 (V4323) by way
of the AC-DC switch and the VOLTS/CM switch.
The AC-DC switch is a two-position slide
switch that bypasses C3300 (C4300) in the
DC position so the input is de coupled. In
the AC position of this switch the Signal must
pass through C3300 (C4300) so the de com-
ponent of the Signal is blocked.
The VOLTS/CM switch is a 9-position rotary
switch that selects the various frequency-
compensated rc attenuator sections. The sen-
sitivity of the unit is .05 volts/cm, The input
voltage is reduced by the eight individually
selected attenuator sections to give nine fixed
calibrated ranges.
Input Stage
The input stage consists of the cathode follower
V3323 (V4323) and the cathode-coupled phase
inverters V3334 and V3354 (V4334 and V4354).
The control-grid de level of V3334 (V4334)
is established by the de connection to the cathode
of V3323 (V4323). The control-grid de level
of V3354 (V4354) is adjustable by means of the
DC B AL Controls so that the de level of the
cathodes of V3334 and V3354 (V4334 and V4354)
can be made equal. Any de level difference
between these two cathodes would actasaSignal
and cause the trace to shift position when the
VARIABLE control is rotated. The VARIABLE
gain control establishes the amount of cathode
SECTION 3
C IR C U IT
DESCRIPTION
coupling and thus allows the stage gain to be
varied over about a 2 1/2 to 1 ränge.
The GAIN ADJ control permits the basic
gain of the unit to be accurately set to agree
with the front-panel calibration.
Polarity and Positioning
With the POLAR ITY switch in the NORMAL
Position the displayed waveform will have the
same polarity as the input Signal. Placing the
PO LAR IT Y switch in the INVERTED position
reverses the signal-grid connection of V3364
and V3374 (V4364 and V4374) and inverts the
displayed waveform. Rotation of theVERTICAL
POSITION control forces one plate of the input
stage toward a higher potential and the opposite
plate toward a lower potential. The resulting
de level shift moves the trace vertically.
Amplifier Stage and Output CF
The Signal is further amplified by V3364
and V3374 or V4364 and V4374, depending on
which channel is conducting. V3364 and V4364
have a common plate load and likewise V3374
and V4374. Since one amplifier is always cut
off while the other is conducting, the shunt
loading effect isnegligible.
V4383 is the output cathode follower that
provides a low-impedance source for driving
the oscilloscope’s vertical amplifier. TheVert.
Pos. Range control located in the grid Circuit
of the output cathode followers permits the trace
to be centered vertically under no-signal con-
ditions.
SW ITC H ING C IRC U IT
A O N L Y , B O NLY
V3375 is a multivibrator that is controlled
AA Circuit Description - Type CA 3-1

by the MODE switch. With the MODE switch
in the A ONLY or B ONLY position the
multivibrator is held in one of its two possible
States by returning one grid to a positive
voltage and the other grid to a negative voltage.
F or example, in the A ONLY position the grid
of V3375A is held positive and this half of the
multivibrator conducts while the grid of V3375B
is held negative and this half is cut off. When
V3375A is conducting the cathode is above
ground which causes V3384B to conduct and it
in turn pulls the grid of V3393B toward ground
lowering the plate voltage of V4334 and V4354.
This reduced plate voltage cuts off the following
stage (V4364 and V4374) and the B-channel
am plifier is held in a non-conducting state.
The converse is true of the A-channel amplifier.
The grid of V3384A is near ground potential
with reduced plate current, therefore, the plate
of V3384A and consequently the grid of V3393A
are permitted to become more positive thus
providing plate voltage for V3334 and V3354.
The A-channel amplifier then conducts.
A LT ER N A TE
Turning the MODE switch to the ALTERNATE
Position returns both grids of the multivibrator
to a negative potential. It is then a bistable
multivibrator. At the end of each sweep cycle
a negative-going trigger is generated and is
coupled to the multivibrator through the Trigger
Coupling Diode V3382. Each trigger causes
the multivibrator to " flip" from one stable
state to the other. This alternately switches
the amplifiers on and off. The switching rate
is now determined by the repetition rate of
the sweep.
CHOPPED
Turning the MODE switch to the CHOPPED
Position returns both grids of the multivibrator
to a positive voltage and the multivibrator
free runs at a rate determined by the time
constant of the grid circuits. The two amplifiers
are alternately cut off and allowed to conduct
at the free-running rate of the multivibrator.
ADDED ALGEBRAICALLY
Turning the MODE switch to the ADDED
ALGEBRAICALLY position returns both grids
of the multivibrator to a negative voltage. Both
sides of the multivibrator (V3375) are held
sufficiently negative so that incoming triggers
have no effect on the multivibrator grids.
The cathodes of both halves of the multivibrator
follow the grids down, driving V3384A and
V3384B to cut off. With V3384A and V3384B
cut off the plate voltage rises, carrying the
grids of the following stages, V3393A and V3393B
with it. The cathodes of V3393A and V3393B
follow the grids up. When the cathodes are
up, both amplifier channels conduct equally
in the absence of any Signal.
Note
Plate voltage for the input ampli
fie r stages of both channels is
supplied by the cathodes of either
V3393A or V3393B.
Under the conditions described above Signals
applied to both inputs will be amplified equally
by either channel. Algebraic addition of the
Signal occurs at the grids of the output stage,
V4383. In phase input Signals add, out of
phase input Signals subtract, at the grid of
each tube if the polarity switches are at the
same setting.
3-2 Circuit Description - Type CA AA

PREVENTIVE MAINTENANCE
Calibration
The Type CA Plug-In Unit is designed for
maximum stability and should not require fr e 
quent recalibration. However, to insure the
accuracy of measurements , we suggest that you
recalibrate the instrument after every 500-
hour period of Operation (or every six months
if the unit is used intermittently). A complete
step-by-step procedure for recalibrating the
unit and checking its Operation is given in the
Calibration section of this manual. The accuracy
of measurements made with the Type CA Unit
depends not only on the accuracy of the Type
CA Unit calibration but on the associated
oscilloscope calibration as well. Therefore, it
is essential that the oscilloscope be maintained
in proper calibration.
Visual Inspection
Many potential and existent troubles can be
detected by a visual inspection of the unit.
fo r this reason, you should perform a com
plete visual check every time the instrument
is recalibrated or repaired. Apparent defects
may include loose or broken connections, dam-
aged connectors, improperly seated tubes,
scorched or burned parts, or broken terminal
strips, as well as many other troubles. The
remedy for these troubles is readily apparent
except in the case of heat-damaged parts.
Damage of parts due to heat is often the direct
result of other, less apparent troubles in the
Circuit. It is essential that you determine the
cause of overheating before replacing the
damaged parts to prevent damage to the new
components.
COMPONENT REPLACEMENT
The procedures for replacing most parts
in the Type CA Unit are obvious. Detailed
SECTION 4
MAINTENANCE
instructions for their removal are therefore
not required. Other components, however, can
best be removed if a definite procedure is
followed or if certain precautions are taken.
Additional information for the replacement of
some of these parts is contained in the following
paragraphs. Because of the nature of the
instrument, replacement of certain parts will
require that you recalibrate portions of the
instrument to insure proper Operation. Refer
to the Calibration section of this manual.
Tubes
Care should be taken both in preventive and
corrective maintenance that tubes are not
replaced unless they are actually causing a
definite Circuit malfunction. Many times during
routine maintenance it will be necessary for you
to remove tubes from their sockets. It is
important that these tubes be returned to the
same sockets unless they are actually defective.
Needless replacement or switching of tubes
will many times result in unnecessary
recalibration of the instrument. If tubes do
require replacement, it is recommended that
they be replaced by previously checked high-
quality tubes.
Switches
Methods for removal of defective switches are,
for the most part, obvious and only a normal
amount of care is required. Single wafers
are normally not replaced on the switches
used in the Type CA Unit, and if one wafer
is defective, the entire switch should be replaced.
Switches may be ordered from Tektronix either
wired or unwired as desired.
Soldering and Ceramic Strips
Many of the components in your Tektronix
instrument are mounted on ceramic terminal
AA Maintenance - Type CA 4-1

Strips. The notches in these Strips are lined
with a silver alloy. Repeated use of excessive
heat, or use of ordinary tin-lead solder w ill
break down the silver-to-ceram ic bond. Occa-
sional use of tin-lead solder w ill not break the
bond if excessive heat is not applied.
If you are responsible for the maintenance of
a large number of Tektronix instruments, or if
you contemplate frequent parts changes, we
recommend that you keep on hand a stock of
solder containing about 3% silver. This type
of solder is used frequently in printed circuitry
and should be readily available from radio-
supply houses. If you prefer, you can order
directly from Tektronix in one-pound rolls.
Order by Tektronix part number 251-514.
Because of the shape of the terminals on
the ceram ic strips it is advisable to use a
wedge-shaped tip on your soldering iron when
you are installing or removing parts from
the strips. Fig. 4-1 will show you the correct
shape for the tip of the soldering iron. Be
sure and file smooth all surfaces of the iron
which will be tinned. This prevents solder
from building up on rough spots where it
will quickly oxidize.
D120
Fig. 4-1. Soldering iron tip properly shaped and tinned.
When removing or replacing components
mounted on the ceramic strips you will find
that satisfactory results are obtained if you
proceed in the manner outlined below.
1. Use a soldering iron of about 75-watt
rating.
2. Prepare the tip of the iron as shown in
Fig. 4-1.
3. Tin only the first 1/16 to 1/8 inch of the
tip. For soldering to ceramic terminal
strips tin the iron with solder containing
about 3% silver.
4. Apply only one com er of the tip to the
notch where you wish to solder (see Fig.
4-2.
Fig. 4-2. C orrect method of applying heat in soldering to a ceram ic
strip.
5. Apply only enough heat to make the solder
flow freely.
6. Do not attempt to fill the notch on the Strip
with solder; instead, apply only enough
solder to cover the wires adequately, and
to form a slight fillet on the wire as shown
in Fig. 4-3.
Fig. 4-3. A slight fille t of sold er is form ed around the w ire when
heat is applied correctly.
In soldering to metal terminals (for example,
pins on a tube socket) a slightly different tech-
nique should be employed. Prepare the iron
as outlined above, but tin with ordinary tin-
lead solder. Apply the iron to the part to be
soldered as shown in Fig. 4-4. Use only enough
heat to allow the solder to flow freely along
the wire so that a slight fillet will be formed
as shown in Fig. 4-3.
4-2 Maintenance - Type CA AA

Fig. 4-4. Soldering to a terminal. Note the slight fille t of so ld er--
exaggerated fo r c larity --fo r m e d around the w ire.
General Soldering Considerations
When replacing wires in terminal slots clip
the ends neatly as close to the solder joint as
possible. In clipping ends or wires take care
the end removed does not fly across the room
as it is clipped.
Occasionally you will wish to hold a bare
wire in place as it is being soldered. A
handy device for this purpose is a short
length of wooden dowel, with one end shaped
as shown in Fig. 4-5. In soldering to terminal
pins mounted in plastic rods it is necessary
Fig. 4-5. A soldering aid constructed from a 1/4 inch wooden dowel.
to use some form of " heat sink" to avoid
melting the plastic. A pair of long-nosed pliers
(see Fig. 4-6) makes a convenient tool for this
purpose.
Ceramic Strips
Two distinct types of ceramic Strips have
been used in Tektronix instruments. Theearlier
type mounted on the chassis by means of
#2-56 bolts and nuts. The later type is mounted
with snap-in plastic fittings. Both styles are
shown in Fig. 4-7.
To replace ceramic Strips which bolt to the
chassis, screw a #2-56 nut onto each mounting
bolt, positioning the nut so that the distance
between the bottom of the nut and the bottom
of the ceramic Strip equals the height at
which you wish to mount the Strip above the
chassis. Secure the nuts to the bolts with a
drop of red glyptal. Insert the bolts through
the holes in the chassis where the original
F ig. 4-6. Soldering to a term inal mounted in plastic. Note the use
o f the long-nosed p lie rs between the iron and the coil form to absorb
the heat.
strip was mounted, placing a #2 starwasher
between each nut and the chassis. Place a
second set of #2 flatwashers on the protruding
Oi*3o
F ig. 4-7. Two types of ceram ic Strip mountings.
AA Maintenance - Type CA 4-3

ends of the bolts, and fasten them firm ly with
another set #2-56 nuts. Place a drop of red
glyptal over each of the second set of nuts
after fastening.
Mounting Later Ceramic Strips
To replace Strips which mount with snap-in
plastic fittings, first remove the original
fittings from the Chassis. Assemble the mount
ing post on the ceramic Strip. Insert the
nylon collar into the mounting holes in the
Chassis. Carefully force the mounting post
into the nylon collars. Snip off the portion
of the mounting post which protrudes below
the nylon collar on the reverse side of the
chassis.
Note
Considerable force may he nec-
essary to push the mounting rods
into the nylon collars. Be sure that
you apply this force to that area of
ceram ic strip directly above the
mounting rods.
Color Coding
All wiring in the Type CA Unit is color
coded to facilitate Circuit tracing. Specific
color codes are used to distinguish the leads
for the power-supply voltages obtained from the
oscilloscope. These power-supply leads follow
the Standard RETMA code. The -150 volts
bus wire is coded brown-green-brown; the
+ 350 volts bus is coded orange-green-brown;
the + 225 volts bus is coded red-red-brown
and the +100 volts bus is coded brown-black-
brown. The widest stripe identifies the first
color of the code.
4-4 Maintenance - Type CA AA

ON 5
INTRODUCTION
Information contained in this section is
provided as an aid to recalibrating andchecking
the Operation of the Type CA Plug-In Unit. In
addition, this section may be used to isolate
troubles occuring within the unit.
Apparent troubles in the unit are often the
result of improper calibration of one or more
circuits. Consequently, calibration checks
should be an integral part of the troubleshoot-
ing procedure. Abnormal indications occuring
during calibration checks will often aid in
isolating troubles to a definite Circuit or stage.
In the instructions that follow > the Steps
are arranged in the proper sequence for a
complete recalibration of the instrument. Each
numbered Step contains the information required
to make one check , one adjustment, or a series
of related adjustments or checks. The Steps
are arranged so that unnecessary repetition
of certain checks is avoided.
In each calibration Step only the required
information is given. Detailed instructions per -
taining to normal Operation of the instrument
are not included. If you are in doubt as to
the proper Operation of Controls, refer to
the Operating Instructions.
Controls not mentioned in a particular cal
ibration Step are assumed to be in the positions
they were in during the previous Step. All
test equipment used in any particular Step
should be disconnected at the end of the Step
unless you are instructed to the contrary.
If a single control requires adjustment, it
can be adjusted in the applicable Step of this
procedure without performing other Steps as
well. It w ill be necessary, however, that you
refe r to the calibration steps immediately pre-
C A LIB R A TIO N
PROCEDURE
ceding the adjustment you wish to make to
determine the proper settings for the Controls
not mentioned in that step.
If you suspect that the unit is out of cal
ibration but you are not aware of which par
ticular adjustment will correct the difficulty,
it is usually best to run through the entire
calibration procedure. In this way you can
be certain that the unit is properly calibrated
without resorting to a method of random
experimentation.
EQUIPMENT REQUIRED
The following equipment or its equivalent
is required to perform a complete calibration
of the Type CA Plug-In Unit.
1. Tektronix 540-Series convertible oscillo-
scope or equivalent.
2. DC Voltmeter with sensitivity of at least
20,000-ohms per volt.
3. Ohmmeter.
4. Type 190 or 190A constant-Amplitude Signal
Generator or equivalent, providing constant
amplitude sine waves from about 50 kc to
30 mc with output amplitude constant within
+ or- 2%.
5. Type 105 Square-Wave Generator or equiva
lent with frequency ränge of about 25 cycles
to 1 mc, risetime at least .02 microseconds
and frequency indication accuracy of no
poorer than + or- 3%.
6. Type 107 Square-Wave Generator or equiva
lent with frequency ränge of 400 kc to 1 m c,
peak-to-peak output voltage of at least 0.1
to .5 völts, and risetim e of 3 nanoseconds
or less.
AA Calibration - Type CA 5-1

7. Tektronix 20pf Input Capacitance Standard-
ize r, Tektronix part number 011-022.
8. 50 ohm 5XT attenuator, Tektronix Part
Number 011-032.
9. 50 ohm cable termination, Tektronix Part
Number 011-045.
10. Tektronix Type P52 CoaxialCables,52ohms
characteristic impedance.
11. Tektronix Dual Input Connector, see Fig.
5-1. Tektronix Part Number 003-035.
resistance-to-ground checks at thelö-pininter-
connecting plug. The table below lists the
nominal resistance value from each pin to
ground.
NOMINAL RESISTANCES AT
INTERCONNECTING PLUG
PIN NUMBER RESISTANCE-TO-GROUND
18.5k
20
38.5k
4infinite
5infinite
6infinite
7infinite
80 (MODE switch
at ALTERN ATE)
912k
10 2k
11 6.3k
12 infinite
13 infinite
14 infinite
15 650
16 infinite
12. Miscellaneous alignment tools. See Fig.
5-2.
PROCEDURE
1. Preliminary Check
Install the Type CA Unit in the oscilloscope.
Turn on all the test equipment and allow
15 minutes for it to warm up. Set the oscillo
scope Controls as follows:
Before installing the Type CA Plug-In Unit
in the oscilloscope, make a careful visual
inspection of the wire dress. This is par-
ticularly important if any soldering has been
done to the unit. Then make the following
F ig. 5-2. Low capacitance, insulated alignment tools used to calibrate
the Type C A.
HORIZONTAL DISPLAY INTERNAL
SWEEP (541A)
MAIN SWEEP
NORMAL
(545 A)
TRIGGERING MODE
TRIGGER SLOPE
STABILITY
TIME/CM
AUTOMATIC
-IN T
PRESET
1 MILLISEC
Now preset the Type CA Controls as follows:
VOLTS/CM (A and B) .05
AA 1
5-2 Calibration - Type CA

VARIABLE VOLTS/CM full right (cw)
(A and B)
the trace is within 2 cm of the vertical-system
electrical center.
POLAR ITY (A and B) NORMAL
AC-DC (A and B) DC
DC B AL (A and B) mid-range
With the MODE switch back in the ALTER-
NATE Position measure the voltage from pin
1 or 3, of the 16 pin interconnecting plug,
to ground. This voltage should be between
66.5 volts and 68 volts.
MODE switch ALTERNATE 6. Check for Gas and Microphonics
2. Balancing Output Stage
Connect a shorting strap between pins 1
and 3 of the 16-pin interconnecting plug. Note
the vertical level of the trace. What you have
just found is the vertical-system electrical
center of the oscilloscope.
Now connect the shorting strap between pins
2 and 7 of V4383. The trace should now fall
within 2 cm of the vertical-system electrical
center just observed If it doesn’t, select a
new tube for V4383 which will bring it within
this tolerance.
3. Adjusting DC BAL (R3341 and
R4341)
Position the trace of each channel to the
center graticule line. Now while rotating
the VARIABLE VOLTS/CM control through
its complete ränge, adjust the DC BAL so
that the trace will remain stationary. This
must be done to each channel.
4 . Vertical Position Range
Adjustment (R4376)
Set both of the VERTICAL POSITION Controls
to mid-range. Adjust the Vert. Pos. Range
adjustment so that the two traces will be
equidistant above and below the vertical-system
electrical center found in step 2.
5. Checking PO LA R ITY Switch
Gas check: With the input connectors grounded
turn the AC-DC switches from DC to AC
and observe the vertical drift of the traces.
This drift should not be more than 2 m illi-
meters.
Microphonic check: Rap the Type CA Unit
lightly on the front panel and watch for the
excessive ringing type of microphonics.
7. Check for Proper ALTERNATE
CHOPPED Operation
Reset the oscilloscope's TIME/CM control
to .1 SEC and with the plug-in MODE switch
in ALTERNATE,Position the two traces about
2 cm apart. Check to see that each time the
sweep is triggered the trace alternates between
A and B channels.
For the CHOPPED check set the TIME/CM
switch on the oscilloscope to 10 microsec and
the plug-in MODE switch to CHOPPED. Observe
that the wave form should be approximately
flat on the top and bottom.
8. GAIN ADd. (R3356 and R4356)
Set oscilloscope as follows:
TIME/CM 1 MILLISEC
AMPLITUDE .1 VOLT
CAL IBRATOR
With the MODE switch in ALTERNATE
Position the traces to the center of the CRT.
Now switch the POLAR ITY switches from
NORMAL to INVERTED. The traces should
not shift more than one centimeter.
Set the Type CA as follows:
MODE ALTERNATE
VOLTS/CM ( A and B) .05
Switch the MODE switch to ADDED
ALGEB RAICALLY and the PO LAR ITY switches
to NORMAL. Position the VE RTICAL POSITION
Controls to mid-range and check to see that
VARIABLE VOLTS/CM full right (cw)
(A and B)
AC-DC (A and B) DC
AA Calibration - Type CA 5-3

Connect a jumper between the CAL OUT
connector of the oscilloscope and both of the
vertical input connectors of the Type CA Unit.
With .1 VOLT of calibrator applied to each
channel adjust the GAIN ADJ, of each channel,
for 2 cm of vertical deflection on the CRT.
9. Check Operation of AC-DC Switch
With all Controls set as in Step 8 position
the bottom of the calibrator waveforms to the
center graticule line. Now switch the AC-
DC switch to AC. The waveforms should shift
down so that the center graticule line will
now be approximately through the center of
the waveforms.
10. Check ADDED ALGEBRAICALLY
Position of MODE Switch
Set plug-in Controls to:
AC-DC (A and B) DC
MODE ADDED
ALGEBRA
ICALLY
With the same amount of calibrator Signal
still applied as in step 9 check to see that
there is 4 cm of deflection on the crt.
Now apply one volt of calibrator Signal from
the oscilloscope to each of the vertical inputs
of the Type CA Unit. Turn the A channel
PO LARITY switch to INVERTED. The two
Signals should now cancel each other out within
1 cm. You may adjust the VERTICAL POSITION
Controls to accomplish this cancellation. If
the cancellation just described doesn't take
place, reset the A channel PO LARITY switch
to NORMAL and the B channel POLARITY
switch to INVERTED. Now check for proper
cancellation. The unit is satisfactory if either
condition w ill permit the proper cancellation
of the Signal.
11. Checking VOLTS/CM Switch
Position
Reset the plug-in Controls as follows:
MODE ALTERNATE
POLARITY (A and B) NORMAL
Connect a jumper from the C AL OUT con
nector of A channel of the plug-in. Check for
the correct deflection in each Position of the
VOLTS/CM switch. Now remove the jumper
from A and connect it to B channel. Run
through the check on this channel as you did
on A channel.
Note
At the factory the accuracy of
the VOLTS/CM switch is checked
with an AMPLITUDE CALIBRATOR
Standardizer, which employs 1/4%
resistors.
VOLTS/CM
Switch
AM PLITU D E
C ALIRRATOR VOLTS
V E R TIC AL C RT
DEFLECTION
.05 .2 4 cm
.1 .2 2 cm
.2 .5 2.5 cm
.5 24 cm
122 cm
252.5 cm
520 4 cm
10 20 2 cm
20 50 2.5 cm
AA 1
5-4 Calibration - Type CA