Tektronix 3B4 User manual

INSTRUCTION
MIAN UAL Serial Number
Tektronix, Inc.
S.W. Millikan Way @ P. O. Box 500 ® Beaverton, Oregon 97005 @ Phone [phone] @ Cables: Tektronix
070-431 964

SECTION 1
CHARACTERISTICS
Introduction
The Type 3B4 Time Base plug-in unit is designed to be
used primarily with the Tektronix Type 561A Oscilloscope sys-
tem; however, It can also be used with the other 560-Seriés
systems that use 3B-Series plug-in units such as the Type 564
and Type 567. As part of an oscilloscope system, the Type
3B4 is used as an accurate time base generator or as a
calibrated amplifier for externally generated deflection sig-
nals,
When used with the 567 or RM567, the 3B4 provides a time-
base, but does not activate the digital readout circuitry.
In the 565 or RM565, the 3B4 provides a vertical time-base
for raster applications but does not provide retrace blanking.
The Type 3B4 provides calibrated sweep rates from 0.05
psec/div to 5sec/div in 25 calibrated steps. A five-step,
direct-reading magnification feature provides magnification
up to 40X or 50X, depending on the sweep rate to which
magnification is applied. When the Type 3B4 is used as an
amplifier for externally generated deflection signals, the
magnifier provides five steps of deflection sensitivity, from
0.2 volts/div to 5 volts/div. In addition, a variable control
provides uncalibrated sweep rates and deflection sensitivities
between the calibrated steps. By using the variable control,
uncalibrated sweep rates from 0.05 psec/div to approxi-
mately 12.5 sec/div and deflection sensitivites from 0.2 volts/
div to approximately 12.5 volts/div are available. Uncali-
brated operation is indicated by a neon lamp.
Normally, the Type 3B4 is inserted in the right-hand com-
partment (operator's right, oscilloscope’s left) of the oscillo-
scope and in this position provides horizontal deflection.
When used with the Type 561A, the Type 3B4 can be inserted
into the left-hand compartment of the oscilloscope to provide
a time base that runs vertically on the crt screen. Due to
differences in the horizontal and vertical deflection plate
sensitivities, the Type 3B4 must be calibrated for vertical
deflection use if accuracy is required in such application.
This manual is written with the assumption that the Type 3B4
will normally be used to provide horizontal deflection sig-
nals in a Type 561A.
Triggering
Facilities
TRIGGER MODE Switch Free Run, Auto, Normal,
and Single Sweep
TRIGGERING LEVEL Con- See Tables 1-1 and 1-2.
trol
SLOPE Switch + or —
COUPLING Switch Ac, Ac Low-Frequency Re-
ject, and Dc
SOURCE Switch Internal, Line, External,
and External + 10
TRIGGERING LEVEL Control Voltage Range (external
triggering}
See Table 1-1.
TABLE 1-1
Voltage Range
SOURCE COUPLING Typical Minimum
AC, DC or
EXT AC LF REJ +19 ¥ +15
AC or DC +190 v
EXT + 10 AC LF REJ +150 v
NOTE
The voltage range of the TRIGGERING LEVEL con-
trol indicates the maximum external peak voltage
that will permit triggering at any amplitude point
on the signal. Signals with greater amplitudes can
be used and will provide triggering, but the range
of trigger-point selection is still limited to the TRIG-
GERING LEVEL control voltage range.
Triggering Sensitivity. See Table 1-2.
@1
TABLE 1-2
SOURCE
Voltage Range
AC
AC LF REJ DC
INT
1 minor division of
deflection 30 cps to 20
mc. Outside these
limits requires larger
triggering signal.
1 minor division of
deflection 30 kc to 20
mc. Outside these
limits requires larger
triggering signal.
1 minor division of
deflection dc to 20
me (with trace verti-
cally centered}, Above
20 mc requires larger
triggering signal,
EXT
0.5v 30 cps fo 20 mc.
Outside these limits
requires larger trig-
gering signal.
0.5v 30kc to 20mc.
Outside these limits
requires larger trig-
gering signal.
0.5v dc to 20mc.
(with trace vertically
centered). Above 20
mc requires larger
triggering signal.
1-1

Characteristics—Type 3B4
Automatic Triggering. In this mode of operation a
bright-line sweep is displayed automatically in the absence
of a trigger. The sweep triggering characteristics stated pre-
viously also apply for automatic triggering except that the
triggering signal must be higher than about 20cps. The
TRIGGERING LEVEL control operates when a triggering sig-
nal is present.
Single Sweep. This feature permits only one triggered
sweep following each reset pulse. The reset pulse is gen-
erated by pressing the PUSH TO RESET button. The trigger-
ing characteristics stated previously apply.
EXT TRIG IN Connector Input Characteristics. See Table
1-3.
TABLE 1-3
TRIG
729
fe)
Rp
|
—0o
ot
Rp Input
SOURCE | COUPLING| C, C, {Meg ©) {Voltage
(pf) Max Peak
DC 220 [shorted [ ~1 +75
EXT AC 20 |=0.01 ph] = +500
AC LF REJ | =20 |100 pf | 0.09 | +500
EXT DC = shorted | 10 500
+ AC = 20.01 wf} 10 +500
10 AC LF REJ | 20 |=100pf | = +500
Sweep
Facilities
TIME/DIV 0.2 psec/div to Ssec/div in 23 steps, I,
Switch 2, 5 sequence. The calibration accuracy
(unmagnified) is 3% from 0.2 wsec/div
to 2 sec/div; 5% at 5 sec/div.
VARIABLE Uncalibrated variable time/div control.
Control Multiplies the sweep time/div of any step
of the TIME/DIV switch by a factor vari-
able from 1 to >2.5.
POSITION Coarse horizontal positioning to position
Controls any portion of the trace to the center of
the crt. The FINE control has a range of
about 2 minor divisions.
MAGNIFIER Provides direct readout magnification of
Control the sweep (up to 50°). The magnifier also
provides the 0.05 and 0.1 psec/div sweep
rates. Magnified sweep accuracy, —-5%
(exception: 5 sec/div). Magnified sweep
registration, +1 minor division,
1-2
+ GATE OUT Provides a +20-volt (+15%) output pulse
Connector during sweep time.
Sweep Length 10.5 +0.3 major division.
Sweep Amplifier (when used as an external hori-
zontal amplifier)
Facilities
HORIZONTAL Calibrated volts/div steps of 0.2, 0.5, 1,
VOLTS/DIV 2, and 5 volts/div. Accuracy +3% when
Switch calibrated to match the oscilloscope in
which used. The amplifier is de coupled
to the EXT HORIZ IN connector.
VARIABLE Multiplies volts/div of any step by a factor
Control variable from 1 to >2.5.
EXT HORIZ Input R and C is typically 1 megQ shunted
IN Con- by 40 pf.
nector
Frequency De to 400 kc. Response <30% down at
Response 400 ke with the VARIABLE control set to
CALIB position.
Maximum Input +20 volts dc, or 20 volts peak ac.
Voltage
Environmental
Operating
TEMPERATURE 0° C to +50° C.
ALTITUDE 10,000 feet maximum.
VIBRATION 0.015 inch peak-to-peak, (1.9 Gs) for 15
minutes along each axis. Vibration fre-
quency varied from 10-50-10 cps in 1-
minute cycles.
Non Operating
TEMPERATURE —35° C to +60° C.
ALTITUDE 50,000 feet maximum.
VIBRATION —0,015 -£0.003 inch total displacement from
10 to 5 cycles.
TRANSIT Meets National Safe Transit type of test
when factory packaged: Vibration for one
hour at slightly greater than 1G. 30-inch
drops on corners, edges and flat surfaces.
Mechanical
Construction Aluminum-alloy chassis with chrome-plated
side rails. Front panel is photo-etched
and anodized.
Dimension 6%, inches high, 4%, inches wide, 147,
(approx.) inches deep (overail).
Net Weight 4.5 pounds.
Accessories
Information on accessories for use with this instrument is
included at the rear of the mechanical parts list.
—

SECTION 2
OPERATING INSTRUCTIONS
Front-Panel Controls and Connectors
See Fig. 2-1.
NOTE
A more complete description of the controls and
connectors is included under ‘‘Standard Sweep Op-
eration” later in this section.
TRIGGER MODE Selects the manner in which the Time Base
Switch
FREE RUN
AUTO
NORM
SINGLE
SWEEP and
PUSH TO
RESET
SOURCE
INT
LINE
EXT
and
EXT + 10
COUPLING
AC
AC LF REJ
DC
sweeps are initiated. For example:
In this position, recurrent sweeps are pro-
vided. The completion of one sweep
causes the next to begin.
Automatic sweep. Permits each sweep to
be triggered when the triggering-signal
repetition rate is about 20 cps or greater.
For lower repetition rates or in the
absence of a triggering signal, the sweeps
are recurrent, as in the FREE RUN posi-
tion.
Normal method of operation. Each sweep
is triggered by the signal from the inter-
nal trigger generator,
Often used when displays of non-repetitive
signals are photographed. When the lamp
inside the PUSH TO RESET button is lit, the
time base is ready to produce one trig-
gered sweep.
Selects the source of the triggering signal:
Internal. Obtains the sweep triggering
signal from the vertical plug-in unit.
Obtains the sweep triggering signal from
a low-voltage winding on the oscilloscope
power transformer.
Permits external signals applied to the
EXT TRIG IN connector to be used for
sweep triggering. High-amplitude _ trig-
gering signals can be attenuated by using
the EXT + 10 position.
Permits acceptance or rejection of some
triggering signal characteristics:
Rejects dc and attenuates very low-fre-
quency ac triggering signals.
Ac low-frequency reject. Rejects de and
discriminates against low-frequency ac
triggering signals. The 30% down point
is 17 ke.
Accepts ac and dc triggering signals,
SLOPE (+ or —) Determines whether triggering will occur
during the positive-going (+) or negative-
going (—) portion of the triggering signal.
TRIGGERING
LEVEL
TIME/DIV OR
HORIZONTAL
VOLTS/DIV
MAGNIFIER
VARIABLE
&
Selects the amplitude point on the trigger-
ing signal where triggering will occur.
Provides 23 calibrated display sweep rates
(unmagnified}. See Fig. 2-1. The number
opposite the dot on the MAGNIFIER knob
skirt always indicates the sweep time per
centimeter as long as the VARIABLE con-
trol is in the CALIB position. The number
bracketed by the two heavy black lines
on the clear plastic knob flange is the un-
magnified sweep time per division. To
change the unmagnified sweep rate, the
concentric flange and the MAGNIFIER
knob must first be interlocked by posi-
tioning the dot on the MAGNIFIER knob
between the two heavy black lines on the
flange. When the flange is positioned so
that the two black lines bracket the EXT
HORIZ IN position, any signal connected
to the EXT HORIZ IN connector is applied
to the horizontal amplifier. In this position
of the switch, the amplified externally
generated signal provides horizontal de-
flection.
Provides magnification of the time base
display up to 40X or 50X in five direct-
reading steps (Magnification of the four
fastest unmagnified sweep rates is limited
to 0.05 psec/div). For example, at 10
magnification, the 5 minor division seg-
ment at the center of an unmagnified crt
display is horizontally expanded to full
graticule width. Any other 5 minor divi-
sion segment of the original unmagnified
display may then be observed in magnified
form by turning the POSITION controls.
To determine the degree of magnification,
divide the number bracketed by the two
black lines on the clear plastic flange by
the number adjacent to the dot on the
MAGNIFIER knob.
Provides continuously variable uncalibrated
sweep rates between about 0.4 and 1.0
times that indicated by the TIME/DIV
switch. Whenever the VARIABLE knob is
not set to CALIB, the UNCAL lamp lights.
When the TIME/DIV switch is set to the
EXT HORIZ IN position, the VARIABLE
knob provides ~ 2.5:1 change in horizontal
amplifier sensitivity.
STANDARD SWEEP OPERATION
The control and switch settings listed under ‘First-Time
Operation" later in this section establish the basic condi-
tions necessary for most measurements. In many applications,
it is desirable for a repetitive signal to produce a stationary
2-1

Operating Instructions—Type 3B4
2-2
TYPE 3B4 TIME BASE
FINE VARIABLE
POSITION TIME/DIV or Tite
HORIZONTAL VOLTS/DIV 2
VOLTS/DIV
PULL MAG
TRIGGER MODE
AUTO NORM
FREE
RUN
SLOPE COUPLING SOURCE
TRIGGERING
AC
INT
EXT
LEVEL
Fig 2-1. Front Panel Controls and Connectors
_——
——

display on the crt so the waveform can be examined in
detail. For this type of display, the start of each sweep
must bear a definite fixed-time relationship to the events
in the input signal. This can be accomplished by using the
displayed signal or another related signal to start (trigger)
single or repetitive sweeps. The following is a detailed
description of the control and switch settings which provide
complete control over the means of triggering the sweep.
It is assumed that the oscilloscopes system is a Tektronix
Type 561A.
TRIGGER MODE
FREE RUN. Free-running operation produces continuously
repetitive sweeps even in the absence of a triggerifg signal.
These sweeps provide a reference trace, as does the AUTO
position. This method of operation is useful in applications
where a device under test requires a trigger or input signal.
The front-panel +GATE OUT signal may be used to operate
the device under test. The resulting signal displayed on
the crt will then be synchronized with the sweep.
AUTO. This position is frequently used for ease of opera-
tion and because of the reference trace produced in the
absence of a triggering signal. The time base free runs with-
out the application of a trigger. If a triggering signal is
received, the free running is interrupted, but this first event
in the signal does not trigger a sweep. If the first signal
event is followed by a second event within about 80 msec,
a triggered sweep is initiated, and if not, the free running
resumes, Since the dormant period is limited to about 80
msec, signal frequencies below about 20 cps cannot produce
a triggered sweep in the AUTO mode. For such signals, the
NORM mode of operation is used.
With the SOURCE switch set to INT and the TRIGGER
MODE switch set to AUTO, the sweep will trigger on any
signal that will trigger the NORM mode (about 1 minor
division of deflection) so long as the triggering signal is
above about 20 cps. When operating in the AUTO mode,
it is necessary to adjust the TRIGGERING LEVEL contro! to
lock the sweep with the triggering signal.
NORM. In the NORM or normal mode, the time base is
dormant in the absence of a triggering signal. Each sweep
must be initiated by a triggering signal.
SINGLE SWEEP. Single sweep is often used when photo-
graphing non-reptitive waveforms and in other applications
where the vertical input signal continually varies in amplitude
shape, or time interval. A continuous display of such signals
would appear as a jumbled mixture of many different
waveforms and would yeild little or no useful information.
The Type 3B4 permits a single sweep to be presented with
the elimination of all subsequent sweeps. The information
in the one sweep is thus clearly recorded without the con-
fusion resulting from multiple nonrepetitive traces.
When the TRIGGER MODE switch is set to SINGLE SWEEP,
the time base becomes inoperative. The time base can be
“reset” to the triggerable condition by pressing the RESET
button. If there is sufficient delay before triggering, the
RESET lamp will light to show that the time base is ready to
be triggered. When the time base has been triggered and
one sweep completed, the time base again becomes inopera-
tive and the lamp extinguishes.
@
Operating Instructions—Type 3B4
SOURCE
INT. It is usually easiest to obtain the sweep triggering
signal internally (INT) from the vertical deflection system.
LINE. If the displayed signal frequency is related to the
power-line frequency, the line source can be used. This
source is useful when the displayed signal does not allow
internal triggering.
EXT. External triggering is often used when signal tracing
in amplifiers, phase-shift networks, and wave-shaping circuits.
The signal from a single point in the circuit can be connected
to the EXT TRIG IN connector through a signal probe or a
cable. With this signal triggering the sweep, it is possible to
observe the shaping, amplification, and time relationship of a
signal at various points in the circuit without resetting the
triggering controls.
EXT. + 10. The only difference between external (EXT)
and external divided-by-10 {EXT + 10) is that the latter
attenuates the external triggering signal. Attenuation of high-
amplitude external triggering signals is desirable to broaden
the TRIGGERING LEVEL contro! range.
DC. De coupling allows the trigger circuits to receive
signals of all frequencies from de upward. It is best to de
couple for very low-frequency signals (below about 20 cps).
AC. Ac coupling rejects the de component of triggering
signals and increasingly attenuates ac triggering signals as
the frequency decreases. This position of the coupling switch
is not normally used for triggering signals below about 20
cps, but this is the most used position of the switch.
AC LF REJ. Ac low-frequency reject coupling rejects the
dc component of triggering signals and increasingly attenu-
ates ac signals as frequency decreases (30% down point
17 ke). If line-frequency hum is mixed with a desired high-
frequency triggering signal, best results are obtained by
using this position of the COUPLING switch.
Ac low-frequency reject coupling should also be used
when triggering internally from multi-trace plug-in units
operated in the alternate-trace mode (unless the “trigger
from a single channel only” feature of the plug-in is used).
For additional information, see the multi-trace vertical plug-
in unit instruction manual.
SLOPE
Sweeps can be triggered during either the rising or falling
portion of the triggering signal. When the display consists
of several cycles of the input signal, either setting of the
SLOPE switch may be used. However, if it is desired to
display less than one full cycle of the input signal, the SLOPE
switch permits the sweep to start on either the rising (+
slope) or falling (— slope).
TRIGGERING LEVEL
The TRIGGERING LEVEL control determines the instanta-
neous voltage on the triggering signal at which the sweep is
triggered, (This instantaneous voltage can also include a dc
2-3

Operating Instructions—Type 3B4
level if the COUPLING switch is set to DC.) With the SLOPE
switch at +, adjusting the TRIGGERING LEVEL control makes
it possible to trigger the sweep consistently at virtually any
point on the positive slope of the triggering signal. Like-
wise, with the SLOPE switch at —, adjusting the TRIGGER-
ING LEVEL control makes it possible to trigger at virtually
any point on the negative slope of the triggering signal.
TIME/DIV OR HORIZONTAL VOLTS/DIV
The Time Base has 23 calibrated sweep rates ranging from
0.2 usec/div to 5sec/div (unmagnified }. See Fig, 2-2. The
number opposite the dot on the MAGNIFIER knob indicates
the sweep time per division as long as the VARIABLE con-
trol is in the CALIB position, The unmagnified sweep rate
value being used appears between the two black lines on
the clear plastic flange of the TIME/DIV control. The VARI-
ABLE control and MAGNIFIER switch, used in conjunction
with the TIME/DIV switch, permit the sweep rate to be varied
continuously between 50 nsec/div and about 12.5 sec/div.
The MAGNIFIER switch is discussed under “MAGNIFIER”.
All sweep rates obtained with the VARIABLE control in any
but the fully clockwise position are uncalibrated, Uncali-
brated sweep rates are indicated when the UNCAL lamp is
lit.
VARIABLE
TIME/DIV or YNPAS
HORIZONTAL VOLTS/DIV
|
ExT
HORIZ IN
Fig. 2-2. TIME/DIV OR HORIZONTAL VOLTS/DIV and MAGNIFIER
KNOBS.
When the flange is positioned so that the two heavy black
lines bracket the EXT HORIZ IN position the horizontal am-
plifier input is connected to the EXT HORIZ IN connector
and accepts external horizontal deflection signals, In this
mode of operation, five ranges of horizontal deflection sen-
sitivity are available. The five sensitivity ranges are from
0.2 volts/div to 5 volts/div.
To position the TIME/DIV switch to the EXT HORIZ IN
position, turn the MAGNIFIER knob until the dot on the knob
2-4
is positioned between the two black lines on the clear plastic
flange. Turn the knob until the two black lines on the flange
bracket the position marked “EXT HORIZ IN". The external
horizontal deflection sensitivity may now be selected by
pulling the MAGNIFIER knob outward to unlock it, then,
while holding the knob out, turn it to the desired volt/div
position,
MAGNIFIER
The sweep ranges between 5 sec/div and 2 usec/div can
be magnified up to 40 or 50 in 5 steps. The degree of
magnification is the ratio between the indicated magnified
rate (number opposite the dot on the skirt of the MAGNI-
FIED knob) and the indicated unmagnified rate (number
bracketed by two black lines on the clear plastic flange).
Since the magnified display rate is always direct reading,
it is seldom necessary to determine the actual magnifying
factor used.
Above 2 ysec/div the number of steps of magnification
decrease until at the .2 uSEC setting of the TIME/DIV switch
only two steps of magnification are available. The .2 .SEC
postion is the highest sweep rate to which the TIME/DIV
switch can be set, but by the use of the two additional mag-
nified positions, and effective sweep rate of 50 nSEC/DIV is
obtained.
FIRST-TIME OPERATION
The following contro! and switch settings for the Type
3B4 can be used for a wide range of measurements, The
operating conditions established by these settings also pro-
vide a starting point for the operator who is learning to
use the instrument.
TRIGGER MODE AUTO
COUPLING AC
SOURCE INT
VARIABLE (TIME/DIV} CALIB [fully clockwise}
MAGNIFIER Locked to TIME/DIV
switch
The Type 384 now provides the time base for measure-
ments of vertical deflection signals above about 20 cps. In
many cases, only the TIME/DIV switch and the TRIGGER-
ING LEVEL control require readjustment when progressing
from one measurement to the next.
The appropriate TIME/DIV switch setting depends on the
frequency of the applied signal and the type of measurement.
For example, to observe about 2 cycles of the oscilloscope
60 cycle Calibrator signal, set the TIME/DIV switch to 5
mSEC.
The following conditions must exist to obtain a triggered
display of the vertical deflection signal with the preceding
control settings:
1. The frequency of the vertical deflection signal must
be about 20 cps or greater (below 20 cps, the TRIGGER
MODE switch must be set to NORM).
2. At SOke the vertical deflection amplitude must be at
least 1 minor division. See Table 1-2.