Tektronix 3S3 User manual

INSTRUCTION
MAN
UAL
Serial
Number
Tektronix, Inc.
S.W.
Millikan
Way
@
P.
O.
Box
500
@
Beaverton,
Oregon
97005
@
Phone
644-0161
@
Cables:
Tektronix
070-0759-00
468

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TYPE 3S2 SAMPLING UNIT
A
POSITION
B
POSITION
DC
OFFSET
+1¥V
DUAL-TRACE
DC
OFFSET
+1V
DOT
RESPONSE
mVOLTS/DIV
mVOLTS/DiV-
TYPE
S-1
i
TYPE
S25)
SAMPLING
HEAD
oF
~
SAMPLING
HEAD
RISETIME
<350ps
Fig. 1-1. Type 352 Sampling Unit.

Type 382
SECTION I
SPECIFICATION
Change information, if any, affecting this section will be found at the
rear of the manual.
General Information
The Type 382 Sampling Unit is a dual-channel vertical
amplifier plug-in unit designed for operation in any one
of the Tektronix Type 560-Series Oscilloscopes except the
Type 561 (it will operate in the Type 561A). The Type 382
accepts ‘'S' Series sampling heads. The sampling heads
determine the input characteristics of the sampling unit
and the availability of the trigger pickoff.
The Type 382 will operate with any Tektronix 3T-series
sampling unit. The Type 3T2 Random Sampling Sweep is
recommended, because it can display the triggering event
without a pretrigger or signal delay line. Conventional or
real time 2B- or 3B-series time-base units include the Types
2B67, 3B1, 3B4 and the 3B5 non-digital time bases, and the
Type 3B2 Analog/Digital Time Base Unit. The Type 382
provides the vertical information needed for voltage meas-
urements by Tektronix digital readout systems, such as the
Type 567-Type 6R1A, or the Type 568-Type 230.
One or two “S” Series sampling heads can be plugged
into the Type 3S2, or used remotely on an optional exten-
der cable unit. The Type 3S2 provides the power for the
sampling heads.
Interconnections to the circuits in the sampling heads are
provided by connectors in the sampling head compartments
of the Type 382.
If a trigger pickoff is provided in the sampling head, the
Type 352 provides a trigger selection circuit and returns a
portion of the input signal to the front panel for externally
triggering a sampling sweep unit. An internal reconstructed
signal is provided to trigger the real-time time-base.
Sampled signals are presented to both the oscilloscope
CRT and to the front panel connectors for external use with
auxiliary equipment such as pen recorders. The two Chan-
nels may be displayed either individually or in one of three
combined modes: DUAL-TRACE, A+B (Algebraic addition},
or a VERT/B HORIZ (X-Y). The A VERT/B HORIZ (X-Y)
mode does not apply in real time operation.
ELECTRICAL CHARACTERISTICS
Digital Unit Compatibility
The Type 3S2 is compatible for operation with all Type
230 Digital Units and all Type 6RIA Digital Units. It is
compatible with ail Type 6R1 Digital Units SN 695 and up.
The Type 6R1 Digital Units SN 101-694 require the installa-
tion of Tektronix Modification Kit 040-0342-00 when oper-
ating with a Type 3872.
The following characteristics apply over an ambient tem-
perature range of 0°C to + 50°C. These characteristics
apply only after the Type 3S2 VERT GAIN control has been
properly adjusted for the oscilloscope and after a sufficient
warm-up time. For particular system warm-up requirements,
refer to the main frame oscilloscope instruction manual. A
procedure for mating the Type 3S2 to each oscilloscope can
be found in the Operating Instructions section.
The Type 382 meets the tolerances stated below after a
5-minute warmup.
ELECTRICAL CHARACTERISTICS
Characteristic
Performance Requirement
Supplemental Information
Deflection Factors
Units/Div Switch Range
2 to 200 in 7 steps in a 1-2-5 sequence with
Units/Div labeled on the sampling head.
Accuracy
Within 3%, NORMAL; 6% SMOOTH
Normal sequential sampling with at
least 20 samples per cycle of displayed
square wave.
Units/Div VARIABLE Range
Reduction in deflection to 0.7 or less when
control is turned CCW from CAL position, and
2.5 times or more increase in deflection when
control is turned CW from CAL position.
Interchannel Delay Range
At least +5ns ‘to —5ns.
With two same type sampling heads
plugged in, using time-coincident sig-
nals.
Loop Gain
NORMAL
control.
Can
be
set
to
unity
with
DOT
RESPONSE
|
Range
of
DOT
RESPONSE
control
is
<0.95 to >1.05.
@1
1-1

Specification—Type 352
ELECTRICAL CHARACTERISTICS (cont'd)
Characteristic
Performance
Requirement
Supplemental
Information
SMOOTH
Loop
gain
is
reduced
to
be
<0.3.
Random
noise
in
display
reduced
to
approx
\.
Dot
Slash
Vertical
dot
drift
is
<
0.1
div
when
sampling
|
Measure
with
Units/Div
switch
at
200
sweep
unit
is
triggered
at
20
Hz.
with
no
signal
input
to
the
sampling
head.
OFFSET
Output
Voltage
Range
+10
to
—10
volts.
Accuracy
Actual
DC
OFFSET
Voltage
is
0.1
X
Source
Resistance
10kQ
within
1%.
OFFSET
Output
voltage
within
2%.
DC
OFFSET
Range
+1
to
—1
volt'.
A
Output,
B
Output
Amplitude
in
Volts
Signal
input
times
Maximum
output
voltage
+4
V.
Source
(Referred
to
Input}
200
Resistance
10kQ,
within
0.5%.
Units/Div
Setting
Accuracy
(Referred
to
Input)
Within
2%.
Accuracy
(Referred
to
CRT)
Within
3%.
(200
mV/Div).
Accuracy
of
Vertical
Signal
to
Within
3%.
Digital
Unit
TRIG
OUT
(SN
B040250-up)
(with
|
Approximately
1
inut
signal
voltage
into
Type
S-1,
5-2}
500
for
AC.
Approximately
.1X
input
sig-
Amplitude
(referred
to
the
Type
|nal
voltage
into
509
for
DC.
Coupling
time
S-1,
S-2
input)
constant
is
5s.
Approximately
1
for
both
AC
and
DC
signals
into
1
MQ.
Risetime
2ns
or
less,
10%
to
90%,
into
50
9
using
70
ps
risetime input pulse
Strobe
signal
in
Trig
Out
Signal
|
<50mV
peak
into
500
TRIG
OUT,
SN
B010101
to
SN
Approximately
0.1
X
input
signal
volt-
B030249
{with
Type
S-1, $-2)
age
DC
coupled
into
509.
Amplitude
(Referred
to
the
Type
Approximately
21/)>
input
signal
volt-
$-1,
$-2
input)
age
into
1
MQ.
Risetime
0.6ns
or
less,
10%
to
50%,
into
500
using
70 ps risetime input pulse.
Strobe
signal
in
Trig
Out
signal
|
<<10
mV
peak
into
50
Q.
Position
Indicator
Lamps
One
indicator
lamp
will
be
on
and
the
other
off
when
CRT
dot
is
more
than
4
divisions
away
from
the
graticule
centerline.
POSITION
Range
>
+5
to
—5
vertical
divisions
from
the
grati-
|
When
DC
OFFSET
is
set
to
deliver
OV
cule
center.
to
OFFSET
output
jack.
1Unless
otherwise
stated
on
the
sampling
head
front
panel.
ENVIRONMENTAL CHARACTERISTICS
Storage
Operating
Temperature—
—40°C
to
465°C.
Operating
Temperature—
0°C
to
+50°C.
Altitude—
To
50,000
feet.
Operating
Altitude—
To
15,000
feet.
MECHANICAL CHARACTERISTICS
Dimensions—
Height
61%
inches
Construction—
Aluminum
alloy
chassis
with
epoxy
laminated
circuit
boards.
Front
panel
is
anodized
alu-
Width
41,
inches
minum.
Length
14¥,
inches
Accessories—
An
illustrated
list
of
the
accessories
supplied
with
the
Type
352
is
at
the
end
of
the
Me-
Approximate
dimensions
including
knobs
and
connectors.
chanical
Parts
List
pullout
pages.

Type 382
SECTION 2
OPERATING INSTRUCTIONS
Change information, if any, affecting this section will be found at the
rear of the manual.
General Information
This section discusses installation, first time operation,
function of front panel controls and connectors, basic opera-
tion and applications of the Type 382. If you are unfamiliar
with sampling, it may be very helpful to read Section 3,
Basic Tektronix Sampling Principles, before proceeding with
this section.
The Type 352 is a special purpose dual-channel sampling
unit designed to operate with the following indicator oscillo-
scopes: Type 561A, RM561A, Type 567, RM567, Type 568, and
R568. The Type 3S2 accepts S-series sampling heads which
determine the input characteristics of the sampling system
and provide a trigger pickoff. For equivalent time sampling,
the sampling system consists of an indicator oscilloscope,
Type 382 with sampling head (or heads), and a sampling
sweep unit. A random sampling sweep unit such as the Type
312 is recommended, because it eliminates the necessity of
pretriggering or signal delay for viewing a repetitive signal.
The Type 3S2 can be used for real time operation with
all real-time time-base units such as Type 2B67, 3B1, 3B2,
3B3, 3B4, and 3B5. An internal trigger source from the
display signal is provided for real time operation.
The vertical deflection factors of 2 to 200 are calibrated
to the units labeled on the sampling head. Sampling head
extender cable units are available to operate the S-series
sampling heads remotely up to 6 feet away. Three-foot
sampling head extender cable is Tektronix Part No. 012-
0124-00. Six-foot sampling head extender cable is Tek-
tronix Part No. 012-0125-00. Contact your local Tektronix
Field Engineer or Representative for price and availability
of these optional accessories.
Installing the Type 3S2 in the Oscilloscope
The Type 382 is designed to drive the vertical deflection
plates of the oscilloscope CRT, and therefore is installed in
the left-hand compartment of the oscilloscope.
NOTE
The Horiz Plug-in Compatibility switch SW6, lo-
cated on the upper portion of the internal bulk-
head immediately behind the front panel, must be
set to agree with the type of time base used.
To insert the Type 382 into the oscilloscope compartment,
turn the aluminum knob (at the front panel bottom center)
counterclockwise several turns until it stops. Then slide the
Type 382 completely into the compartment. Once the plug-
in unit is seated, turn the aluminum knob a few turns clock-
wise until it is hand-tight.
®
The Type 352 requires at least one sampling head in
order to operate. The sampling head (or heads) can be
plugged into the Type 3S2 or used remotely by use of an
extender cable.
To insert a sampling head into the right or left Channel
compartment of the Type 3S2, slide the unit completely
into the compartment, leaving the latch at the bottom of the
unit free to move. Once the sampling head is seated, push
the latch to lock the head in place. To remove, pull the
latch knob away from the panel, then pull the unit from the
compartment. See Fig. 2-1. The same system of connec-
tions applies when using the sampling head extender cable.
_ Horizontal 4
Compatibility
switch SW6
(inside)
* series : : .
‘Sampling Head Latch knob-
Fig. 2-1. Installation information and location of the Horiz Plug-In
Compatibility switch.
Mating
The Type 382 Vertical Output Amplifier gain must be
matched to the indicator oscilloscope CRT deflection factor
for accurate gain measurements. The GAIN control, a screw-
driver adjustment on the front panel adjusts the Vertical
Output Amplifier gain of the Type 3S2. Adjustment of this
GAIN control using the Type 284 Pulse Generator as a signal
source is shown under Equivalent-Time Sampling Operation
which follows. For further Gain information, refer to the
Gain Adjustment instructions later in this section.
2-1

Operating Instructions—Type 352
FIRST-TIME OPERATION
Equivalent-time Sampling Operation
Equivalent-time sampling operation of the Type 352 re-
quires
a
sampling
sweep
plug-in
unit
in
the
right
hand
com-
partment
of
the
indicator
oscilloscope.
In
this
First
Time
Operation
procedure,
a
Type
312
Random
Sampling
sweep
is
used.
The
Type
312
is
recommended
for
use
with
the
Type
382,
because
random
sampling
permits
viewing
the
signal
in
advance
of
the
triggering
event.
Such
trigger
lead-
time
is
required
by
the
Type
3S2
to
view
fast
rise
pulses
while
internally
triggering
the
sampling
sweep
unit
from
the
TRIG
OUT
connector.
The
Type
561A
Oscilloscope
is
used,
and
a
Type
284
Pulse
Generator
is
used
as
a
signal
source.
Any
S-
Series
sampling
head
can
be
used.
In
this
First
Time
Opera-
tion,
two
Type
S-1
Sampling
Heads
are
used.
If
you
are
not
already
familiar
with
the
operation
of
the
oscilloscope
and
sampling
sweep
unit,
read
the
manuals
for
these
instru-
ments before proceeding.
Single Trace
Make
sure
that
the
internally
mounted
Horiz
Plug-in
Com-
patibility
switch
SW6
is
in
the
Sampling
3T-Series
position.
See
Fig.
2-1
for
its
location.
Also
make
sure
that
the
Samples/
Div
switch
SW450
on
the
Type
3T2
bulkhead
immediately
behind
the
front
panel
is
set
to
the
Variable
(Front
Panel)
position.
Type 3S2
Horiz Plug-In Compatibil- Sampling
ity SWé6 (behind front
panel}
Display Mode CH B
NORMAL-SMOOTH NORMAL
A and B POSITION Midrange
DC
OFFSET
Midrange
(5
turns
from
(both Channels) one end}
Units/Div 200
(both Channels)
VARIABLE CAL
(both Channels}
INVERT Push in
DOT RESPONSE Midrange
(both channels)
B DELAY Midrange
TRIG OUT switch Optional
Type 312
Horiz Position Midrange
Samples/Div
9
o'clock
position
Display
Mode Normal
Start
Point
With
Trigger
Sweep
rate
100 ns
Range
1 ws
Diplay
Mag
x1
Time
Magnifier
XI
Variable Cal
Time Position Both fully clockwise
Trig Sensitivity Fully clockwise
Recovery Time Optional
Trigger Polarity +
Trigger Source Ext
Type 284
Square Wave Amplitude 1.0V
Period 1 ps
Mode Square Wave Output
Lead Time 75 ns
Connect
the
Square
Wave
Output
signal
from
the
Type
284
to
the
input
connector
of
the
Sampling
Head
installed
in
the
Channel
B
compartment
through
a
5ns
coaxial
cable.
Any
applied
signal
(to
Type
S-i)
should
be
1
volt
or
less.
This
is
the
normal
signa!
range
for
the
Type
S-1.
See
the
sampling
head
specification
of
the
Type
S-1
or
the
S-
Series
sampling
head
you
are
using
for
further
information.
Connect
the
Trigger
Output
signal
from
the
Type
284
to
the
50Q
external
Trigger
Input
connector
on
the
Type
312
through
a
5Sns
signal
delay
coaxial
cable
with
BNC
con-
nectors.
Center
the
trace
on
the
graticule
with
the
A
POSITION
control,
and
if
necessary
use
the
DC
OFFSET
control.
Ad-
just
the
Trig
Sensitivity
control
on
the
Type
312
counter-
clockwise,
then
clockwise
for
a
stable
trace.
Observe
a
square
wave
display.
If
its
amplitude
is
5
vertical
divisions,
the
Type
352
GAIN
adjustment
on
the
front
panel
is
prop-
erly
set.
If
the
amplitude
is
not
5
vertical
divisions,
adjust
the
GAIN
control
with
a
small
screwdriver
for
5
vertical
divisions.
Now
check
Channel
A
by
applying
the
input
signal
to
the
input
connector
of
the
sampling
head
installed
in
the
Channel
A
compartment.
Change
the
Display
Mode
switch
to
CH
A.
NOTE
Operating
the
sampling
head
without
the
input
connector
terminated
by
a
50
©
resistor
or
coaxial
cable
will
cause
a
vertical
shift
to
the
zero
signal
baseline
by
a
few
millivolts.
This
occurs
because
the
strobe
kickout
signal
is
reflected
from
the
open
input
connector.
The
kickout
signal
arrives
back
at
the
sampling
bridge
during
sampling
time,
while
the
bridge
is
still
conducting.
To
avoid
this,
set
the
display
zero
reference
point
with
the
input
circuit
connected,
not
before
connecting
it.
Also
use
at
least
20cm
of
airline
between
the
Type
S-1
input
and
a
fast
generator
or
circuit
that
is
sensitive
to
the
fast
Strobe
kickout
signal.
Experiment
with
the
various
Channel
B
front-panel
con-
trols,
and
notice
the
effect
of
each.
For
example,
note
the
effect
of
the
POSITION
control
in
positioning
the
display
above
and
below
the
zero
reference
level
at
the
graticule
centerline.
Return
the
Position
control
back
to
midrange,
and
turn
the
DC
OFFSET
control
counterclockwise
to
posi-
tion
the
upper
portion
of
the
square
wave
to
the
graticule
centerline.
This
new
reference
level,
set
by
the
DC
OFFSET
control,
can
be
monitored
at
the
OFFSET
X10
10
kQ
jack.
®

Now, notice that the POSITION control positions the dis-
play above and below the new reference level.
FUNCTION OF FRONT PANEL
CONTROLS AND CONNECTORS
A special removeable knob is used on the three controls A
DOT RESPONSE, B DOT RESPONSE and B DELAY allowing
these controls to be screwdriver adjusted. Knob removal
may be an operator convenience in production line appli-
cations. Pull the knob away from panel to remove. Observe
the internal spring wire orientation before replacing a knob.
The spring wire should slide into the control shaft screw-
driver slot to prevent knob slippage at the end of control
rotation.
Display Mode Selects one of the five following display
Switch modes.
CH
A The Channel A signal is displayed.
CH B The Channel BB signal is displayed.
DUAL-TRACE Both channel signals are displayed, but
each trace has one-half the normal number
of dots per sweep. The display switches
from CH A to CH B after each CH A dot,
and vice versa. While operating in Dual-
Trace, one sweep contains the same num-
ber of dots as if only one channel were
displayed.
A+ 8B The algebraic sum (A-+B as selected
with the INVERT switches) of the two Chan-
nels is displayed.
A VERT The Channel A signal is displayed ver-
B HORIZ tically and the Channel B signal is dis-
played horizontally for X-Y operation.
Functions only with sampling sweep units.
NORMAL- Selects unity loop gain at NORMAL,
SMOOTH (Red and reduces the loop gain to <0.3 at
knob concentric SMOOTH. NORMAL provides the correct
with the Display loop gain required when measuring rise-
Mode switch} time. SMOOTH reduces the effect of
random noise on the display while re-
quiring high sampling dot density for the
correct displayed risetime.
POSITION Adjust the vertical position of the A and
Controls B displays independently. (The B_ posi-
tion control becomes the horizontal posi-
tion control in the A VERT B HORIZ mode.}
DC OFFSET These controls apply internal signal offset
+1¥V Controls voltages of +1 to —1 volt to the sampling
head (unless otherwise stated on the sam-
pling head front panel}. The input signal
zero reference (related to the CRT) is the
DC Offset voltage instead of ground.
Permits all portions of a maximum -++1-volt
input signal to be positioned through the
CRT vertical ‘window’ even at a deflec-
tion factor of 2 units/div (2mV/Div with
a Type S-1 or S-2}.
The vertical window is a total of 14mV
when the deflection factor is 2mV/Div,
and 1.6 volts when the deflection factor
is 200 mV/Div. The front panel OFFSET
monitor jacks allow accurate slide-back
@3
Units/Div
Switches
VARIABLE Con-
trols (Same con-
trol knob with
INVERT
Switches)
INVERT
Switches
DOT RESPONSE
GAIN
TRIG OUT
Aor B
Switch
B DELAY
VERT OUTPUTS
A OUTPUT
.2V/DIV,
10 ka
Operating Instructions—Type 382
voltage measurements to be made of part
or all of a signal at 10X the actual offset
voltage applied to the head.
Selects calibrated deflection factor for
each Channel. The units are selected and
named on the adjacent S-Series sampling
head. For example, with a Type S-1 sam-
pling head in Channel A and the Chan-
nel A Units/Div switch set at 100, each
major division of deflection corresponds
to 100 millivolts of applied signal at the
S-1 input connector when the VARIABLE
Control is in the CAL position.
Provides + and — Uncalibrated variation
of the deflection factor between labeled
values of the Units/Div switches. Counter-
clockwise rotation decreases the display
size, increasing the deflection factor to at
least 3.43 times the Units/Div calibrated
value (display is <0.7 as large as when
VARIABLE is at CAL). Clockwise rotation
increases the display size, decreasing the
deflection factor to at least 0.4 times the
Units/Div calibrated value (display is
>2.5 as large as when VARIABLE is at
CAL).
In the Normal (pushed in) position, a pos-
itive input signal deflects the CRT beam
upward. In the pulled position the dis-
played signal is inverted. When the Dis-
play Mode switch is set to A + B, alge-
braic addition of Channels A and B is
obtained. The position of the INVERT
switches determines the polarity of each
channel before algebraic addition.
Allows the loop gain of each Channel
to be adjusted to unity when the NOR-
MAL-SMOOTH switch is in the NORMAL
position.
Matches the vertical output amplifier gain
to the oscilloscope CRT deflection factor.
(Does not affect the internal Digital Gain
accuracy.)
When the sampling head contains a trig-
ger pickoff circuit, selects the signal from
Channel A or Channel B input circuit. De-
livers the signal to the TRIG OUT jack
on the front panel. (Such signals are use-
ful for externally triggering a sampling
sweep unit). It also selects an internal
vertical signal facsimile from channel A
or B for use in internal triggering of real-
time time-base units.
Varies the time position of CH B display
over a range of af least 10ns. Time
coincidence will depend upon the time
difference of sampling heads and sampling
head extender cable units.
The Channel A facsimile signal (the same
Memory output signal that drives the Ver-
tical Amplifier) is available at this con-
2-3

Operating Instructions—Type 3$2
TEKTRONIX ©
(— \
TYPE 3S2 SAMPLING UNIT
A
POSITION
B
POSITION
DC
OFFSET
+1V
DUAL-TRACE
DC
OFFSET
+1V
CHA CHB
A VERT
B HORIZ A+B
pot GAIN B DELAY
NORMAL SMOOTH DOT
RESPONSE
©
TRIG
OUT
RESPONSE
© ~CT)s ©
os ICAL LZY-y,
P59 20 10 a S QW
POSITION 200
OF
PORTLAND, OREGON, U.S.A.
(—
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(a
—))
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mVOLTS/DIV
TYPE
S-1
TYPE
S-1
SAMPLING
HEAD
SAMPLING
HEAD
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Q
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—
RISETIME
RISETIME
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£350ps
{
TEKTRONIX
®
+5V
MAX
LTEKTRONIX
®
S
ey
GND
VERT
OUTPUTS
.
2v/DIV
A
10KQ
OFFSET OFFSET
X10
10KQ
X10
10KQ
Fig. 2-2. Control
Setup Chart.

nector. The front panel labeled open-
circuit deflection factor of 0.2V per divi-
sion of CRT deflection applies only when
the Units/Div VARIABLE control is at its
CAL detent position. {The VARIABLE con-
trol alters the CRT deflection factor but
does not change the signal amplitude fed
to the VERT OUTPUT jacks.) Maximum
open-circuit signal amplitude is +4 volts
for all Units/Div switch controlled deflec-
tion factors. Output voltage swing is not
limited to the magnitude displayed on the
CRT. Permits a non-sampling type oscillo-
scope to monitor the facsimile signal the
equivalent of 40 CRT divisions when the
Units/Div switch is at 2 (mV/Div). Output
resistance is 10kQ. Output amplitude is
not affected by the Display Mode switch
position.
B OUTPUT Performs the same function for Channel
.2V/DIV, B.
10 kQ
A OFFSET Unless otherwise specified on the sampling
X10 10 ka head front-panel, the open-circuit voltage
at this jack is 10 times the internal DC
Offset voltage as set by the Channel A
DC OFFSET control. The output resist-
ance is 10kQ.
B OFFSET Unless otherwise specified on the sampling
X10 10 ko head front panel, the open-circuit voltage
at this jack is ten times the internal DC
Offset voltage as set by the Channel B
DC OFFSET control. The output resistance
is 10kQ.
TRIG OUT When the sampling head contains a trig-
BNC ger pickoff circuit, this connector presents
Connector the input signal (before it is sampled) from
either the Channel A or the Channel B
head, as selected by the TRIG OUT switch.
Signal amplitude into 500 is approxi-
mately equal to the signal input to the
sampling head.
SN _ B040250-up
TRIG OUT When the sampling head contains a trig-
BNC ger pickoff circuit, this connector presents
Connector the input signal (before it is sampled)
SN _ BO10101- from either the Channel A or the Channel!
B030249 B head, as selected by the TRIG OUT
switch. Signal amplitude into 500 ts
approximately equal to the signal input to
the sampling head; amplitude into 1 MQ is
2.5% the input signal. (See Table 2-1
this section.)
Control Setup Chart
Fig. 2-2 is a chart of the Type 3S2 front panel controls,
showing two S-Series sampling heads installed. Also shown,
is the internally located Horiz Plug-In Compatibility switch.
This figure may be reproduced and used as a test setup
record for special applications or procedures, or it may be
used as a training aid for familiarization with this instru-
ment.
@1
Operating Instructions—Type 352
BASIC OPERATING INFORMATION
Dual Trace
The dual-trace feature of the Type 3S2 permits observ-
ing Channels A and B simultaneously. This is useful for
comparing amplitude, risetime, waveshape, and time rela-
tionship of two signals. The sweep may be triggered on
information related to either channel. Be sure to trigger
from the channel with the earliest signal event. Use input
signal cables with equal delays to preserve the time relation-
ship of the two signals.
The B DELAY control adds a variable to the time co-
incidence of Channel B in relation to Channel A sampling
time. The B DELAY range of 10ns will accommodate small
time differences in cables or sampling heads, so that both
signals can be displayed in time coincidence.
For dual trace operation, set the controls as follows:
Type 3S82
Horiz Plug-In Compati- Sampling
bility (behind front
panel}
Display Mode DUAL-TRACE
NORMAL-SMOOTH NORMAL
DC OFFSET Midrange (5 turns from
(both Channels) one end}
POSITION Midrange
(both channels)
Units/Div 100
(both Channels)
VARIABLE CAL
(both Channels)
INVERT Push in
(both Channels)
DOT RESPONSE Midrange
B DELAY Midrange
TRIG OUT switch Optional
Type 3T2
Horiz Position Midrange
Samples/Div 9 o'clock position
Display Mode Normal
Start Point With Trigger
Sweep rate 100 ns/Div
Range 1 ps
Display Mag XI
Time Magnifier x1
Variable Cal
Both fully clockwise
For triggered display
Counterclockwise
Time Position
Trig Sensitivity
Recovery Time
Trigger Polarity +
Trigger Source Ext
Type 284
Square Wave Amplitude 1.0V
Period 1 ps
Mode Square Wave Output
Lead Time Optional
Connect the Square Wave Ouput signal to Channel A
2-5

Operating Instructions—Type 3$2
To
Channel A
502
From f
Type 284
502 el
To
GR 874-TPD Channel B
Coaxial Power Divider 502
(16.67 2 each)
Tektronix Part No.
017-0082-00
Coaxial Power
BNC coaxial cable
Two - 10 ns coaxial
cables
Fig. 2-3. Initial Power divider connections.
and Channel B input connectors through a power divider
and two 5ns coaxial cables. See Fig. 2-3. Connect the
Type 284 Trigger Output signal to the Type 3T2 509 ex-
ternal trigger input connector through a 50 coaxial cable.
Adjust the Type 312 Trig Sensitivity control for a stable
display. Center both traces on the graticule with the POSI-
TION controls, and if necessary use the DC OFFSET controls.
One half of the Type 284 signal is applied to each input.
This properly triggered dual-trace display will be similar
to Fig. 2-4A.
Dot Response. A convenient way to adjust the DOT RE-
SPONSE control so each channel loop gain is unity is to
cause double or multiple triggering of the sweep, so that
each sample must respond to the full 0.5 volt (full signal
amplitude). Turn the Type 312 Trig Sensitivity control clock-
wise into the free-run region, and adjust the Recovery Time
control until the display is similar to Fig. 2-4B. In this typical
double triggered display, Channel A is at less than unity
loop gain, and requires clockwise rotation of its DOT RE-
SPONSE control to obtain a display as shown for Channel
B. Adjust the DOT RESPONSE control for the best flat upper
or lower portions of the square wave display.
NOTE
The maximum allowable amplitude of the signal
into the sampling head input for unity loop gain
depends upon the sampling head used. For ex-
ample, 0.5 V with the Type S-1, and 0.2 V with
the Type S-2.
2-6
Double or multiple triggering is useful to adjust the DOT
RESPONSE control for unity loop gain. However, this
type of display should be avoided in normal operation, since
it is a false triggered display.
B DELAY. To show B DELAY control operation, change
the following controls from the preceding operation:
Type 284
Mode Switch Pulse Output
Type 352
Units /Div 50
(both Channels)
Type 312
Start Point Before Trigger
Sweep rate 2ns
Range 100 ns
Time Magnifier x5
Connect the Pulse Output signal into the power divider
by moving the power divider input to the Pulse Output
connector on the Type 284.
Adjust the Trigger Sensitivity and the Time Position con-
trols on the Type 312 to display Channel A step signal at
the horizontal center of the graticule (see Fig. 2-4C).
@z

Operating Instructions—Type 352
(C) Variable B DELAY operation (double exposure) (C) A + Bone INVERT switch in the out position
Fig.
2-4,
Typical
Displays
to
show
dual
trace
operation.
Fig.
2-5.
Displays
used
to
show
A
+
B
operation.
®
2-7

Operating Instructions—Type 352
Operate
the
B
DELAY
control
to
show
the
variable
time
relationship
between
operation
of
the A
and
B
Channels.
Fig.
2-4C
is
a
double
exposure
display
showing
the
clock-
wise
and
counterclockwise
positions
of
the
B
DELAY
con-
trol.
Adjust
the
B
DELAY
control
to
move
the
Channel
B
step
display
to
the
same
horizontal
position
as
that
of
the
Chan-
nel
A
step
display.
This
coincidence
of
the
two
Channel
displays
shows
that
the
B
Delay
circuit
has
compensated
for
the
small
delay
differences
in
the
two
signal
paths.
A + B
The
algebraic
addition
of
two
signals
can
be
obtained
with
the
Display
Mode
switch
set
in
the
A
+
B
position.
The
variable
B
DELAY
control
can
be
useful
to
compensate
for
small
time
differences
in
the
setup
before
making
accu-
rate
algebraic
addition
of
the
two
signals.
For
accurate
algebraic
addition,
the
sampling
heads
for
Channel
A
and
B
should
be
the
same.
The
following
example
uses
a
single
test
signal
to
both
Channels
through
identical
length
cables
or
probes.
For A + B operation, set the controls as follows:
Type 382
Horiz Plug-In Compati- Sampling
bility (behind front
panel)
Display Mode A+B
NORMAL-SMOOTH NORMAL
A and B POSITION Midrange
DC OFFSET Midrange
(both Channels)
Units /Div 50
(both Channels)
VARIABLE CAL
(both Channels}
INVERT Push in
DOT RESPONSE Midrange
(both channels}
B DELAY As in procedure
below
TRIG OUT Switch Optional
Type 312
Horiz Position Midrange
Samples/Div 9 o'clock position
Display Mode Normal
Start Point With Trigger
Sweep rate l ns
Range 100 ns
Display Mag x1
Time Magnifier x10
Variable Cal
Time Position As required
Trig Sensitivity
Fully clockwise
Recovery Time Optional
Trigger Polarity +
Trigger Source Ext
Type 284
Mode Pulse Output
Lead
Time
75
ns,
Optional
with
Type
3T2 Start Point switch at
Before Trigger.
Connect
the
Pulse
Output
signal
from
the
Type
284
to
the
Channel
A
and
B
input
connectors
on
the
sampling
heads.
Use
a
power
divider
and
two
5ns
coaxial
cables
in
the
ar-
rangement
shown
in
Fig.
2-3.
Connect
the
Trigger
Output
signal
from
the
Type
284
to
the
External
Trigger
input
50Q
connector
on
the
sampling
sweep
unit,
through
a
5ns
signal
delay
500
coaxial
cable.
Initially
set
the
Display
Mode
switch
to
CH
A
or
B
and
set
the
Sampling
Sweep
Unit
for
an
external-triggered
1
ns/
Div
stable
sweep.
Set
the
time
position
control
as
necessary
to
obtain
a
display
similar
to
Fig.
2-5A.
Set
the
Display
Mode
switch
to
DUAL-TRACE
and
adjust
the
B
DELAY
control
until
both
displays
are
in
time
coinci-
dence.
Set
the
Display
Mode
switch
to
A
+
B.
Addition
of
the
two
signals
will
be
displayed.
Turn
the
B
DELAY
control
and
notice
its
effect
upon
the
composite
display.
Fig.
2-5B
shows
the
composite
A
+
B
display
with
the
B
DELAY
control
adjusted
about
Ins
away
from
time
coincidence
of
the
two
signals.
Pull
one
of
the
INVERT
switches,
inverting
one
of
the
Chan-
nel
signals.
Now
any
time
difference
of
the
two
Channel
signals
will
display
a
pulse,
while
those
portions
of
the
two
signals
that
are
equal
and
opposite
will
display
a
straight
line.
Adjust
the
B
DELAY
control
and
notice
the
change
in
polarity
of
the
pulse
as
Channel
B
passes
through
time
coin-
cidence
with
Channel
A.
See
Fig.
2-5C.
Adjust
the
B
DELAY
control
for
minimum
time
difference.
The
display
will
approach
a
single
trace
with
no
vertical
deflection
(if
the
two
sampling
heads
are
identical),
When
the
composite
A
+
B
display
is
a
straight
line,
the
B
DELAY
control
has
adjusted
the
Channel
B
display
to
time
coinci-
dence
with
the
Channel
A
display.
A VERT B HORIZ
A
display
of
Channel
A
vertically
and
Channel
B
hori-
zontally
can
be
obtained
with
the
Display
Mode
switch
in
the A
VERT
B
HORIZ
position.
Use
a
sampling
sweep
unit.
This
unit
contains
the
horizontal
amplifier
and
pro-
vides
the
sampling
drive
pulse
for
the
Type
352.
Use
any
time-related
signals
to
the
input
connectors
of
the
sampling
heads.
The
signals
should
not
exceed
the
input
signal
spec-
ifications
of
the
sampling
heads.
An
initial
adjustment
is
necessary
if
accurate
phase
meas-
urements
{time
relationships)
between
the
two
signals
are
required.
Use
the
variable
B
DELAY
control
to
compensate
for
small
time
differences
between
the
two
Channel
signal
paths.
This
control
acts
as
a
variable
phase
shift
control
for
Channel
B
in
this
A
VERT
B
HORIZ
(X-Y)
operating
mode.
Use
the
same
signal
on
both
Channels,
through
the
®

same setup cable or probes that will be used when making
the phase adjustments. Once the B DELAY is adjusted to
the desired position (usually an in-phase display) the phase
differences between two signals can be shown.
The initial phase adjustment is made in the DUAL-TRACE
position of the Display Mode switch. Use a test pulse-type
fast-rise signal to both Channels through identical length
cables or probes. Tektronix Type 284 is used in the follow-
ing initial adjustment.
Set the controls as follows:
Type 3$2
Horiz Plug-In Sampling
Compatibility
Display Mode DUAL-TRACE
NORMAL-SMOOTH NORMAL
A and B POSITION Midrange
DC OFFSET Midrange (5 turns from
(both Channels) one end)
Units /Div 50
(both Channels}
VARIABLE (both Channels} CAL
INVERT Push in
(both Channels}
DOT RESPONSE Midrange
(both Channels}
TRIG OUT Switch Optional
Type 312
Horiz Position Midrange
Samples/Div 9 o'clock position
Display Mode Normal
Start Point With Trigger
Sweep rate 1 ns/Div
Range 100 ns
Display Mag x1
Time Magnifier X10
Variable Cal
Time Position
Trig Sensitivity
Both fully clockwise
Described below
Recovery Time Optional
Trigger Polarity +
Trigger Source Ext
Type 284
Mode Pulse Output
Lead Time 75 ns
Connect
the
Pulse
output
signal
from
the
Type
284
to
the
Channel
A
and
B
input
connectors
on
the
sampling
heads.
Use
a
power
divider
and
two
5ns
coaxial
cables
in
the
ar-
rangement
shown
in
Fig.
2-3.
Connect
the
Trigger
Out-
put
signal
from
the
Type
284
to
the
External
Trigger
input
50.0
connector
on
the
sampling
sweep
unit
through
a
5ns
signal
delay
500
coaxial
cable.
®
Operating Instructions—Type 3S2
Adjust
the
Type
312
Trig
Sensitivity
control
for
a
stable
display.
Center
both
traces
on
the
graticule
with
the
Position
controls,
and
if
necessary
use
the
DC
OFFSET
controls.
Adjust
the
Time
Position
control
on
the
Type
312
to
display
step
signals
on
both
Channels.
Adjust
the
B
DELAY
control
to
move
the
Channel
B
step
display
to
the
same
position
as
that
of
Channel
A
step
display;
See
Fig.
2-6A.
This
horizontal
time
coincidence
of
the
two
Channel
displays
is
a
preliminary
adjustment,
preparing
the
system
to
measure
the
phase
relationship
of
two
harmonically-related
input
signals
to
the
two
5ns
cables.
Fine
adjustment
is
described
below.
Disconnect the Type 284 Pulse signal generator. Change
the following controls for A VERT B HORIZ (X - Y) operation.
Type 352
Display Mode A VERT B HORIZ
Units/Div As desired
(both Channels)
Type 3T2
Samples/Div Midrange
Trig Sensitivity Fully clockwise
{Leave all other controls
as set)
Use
a
sine
wave
input
signal
into
the
power
divider
in
the
same
setup
as
in
the
initial
setting
above.
The
signal
should
not
exceed
the
specifications
of
the
sampling
heads.
Center
the
display
with
the
POSITION
controls,
and
if
nec-
essary
use
the
DC
OFFSET
controls.
The
A
POSITION
con-
trol
on
the
Type
3S2
will
contro!
the
vertical
position
of
the
display,
and
the
B
POSITION
will
control
the
horizontal
position
of
the
display.
The
display
will
be
similar
to
Fig.
2-6B.
A
fine
adjustment
of
the
B
Delay
control
may
be
re-
quired
to
eliminate
phase
difference
at
the
inputs
of
the
two
5ns
coaxial
cables.
After
these
adjustments,
the
system
is
ready
to
show
ac-
curate
phase
difference
displays
over
a
wide
range
of
fre-
quencies.
Connect
the
signals
to
the
inputs
to
the
two
5ns
coaxial
cables.
Figure
2-6C
shows
a
method
of
calculating
phase
difference
of
two
sine
waves.
Real Time Sampling
For
Real
Time
Sampling
operation
use
a
conventional
or
real-time
time-base
unit
such
as
Type
2B67,
3B1,
3B2,
3B3,
3B4
or
3B5.
The
Type
3S2
provides
100
kHz
clock-
controlled
Strobe
Drive
pulses
to
each
sampling
head,
inde-
pendent
of
the
real-time
time-base
unit.
The
repetitive
Strobe
Drive
pulses
are
turned
on
when
the
internal
Horiz
Plug-in
Compatibility
switch
is
set
to
the
Non-Sampling
position.
A
chopped
replica
trigger
signal
(the
actual
input
signal,
chop-
ped
at
a
100kHz
rate,
amplified
after
the
Memory
circuit},
is
available
for
internal
triggering.
The
front
panel
TRIG
OUT
switch
selects
which
channel
chopped
replica
signal
drives
the
real-time
time-base
unit,
permitting
internal
trig-
gering
from
either
channel.
Real
time
internal
triggering
is
available
even
when
the
sampling
head
does
not
contain
a
trigger pickoff
circuit.
Connect
the
signals
to
be
observed
to
the
input-connectors
of
the
sampling
head
(or
heads)
installed
in
the
Type
3S2.
2-9

Operating Instructions—Type 352
(C) Approx. 30° phase difference. (A is approx. 3 Div)
Fig. 2-6. A VERT B HORIZ operation including (A) initial setup
(Dual Trace) (B & C), 500 MHz X-Y display.
2-10
Input signals should not exceed the input signal specifica-
tions of the sampling head. The following examples use a
Tektronix Type 106 Square-Wave Generator at 1 kHz, then
at 10 kHz.
For single channel real time operation, set the controls
as follows:
Type 352
Horiz Plug-In Non Sampling
Compatibility
Display Mode CHA
NORMAL-SMOOTH NORMAL
DC OFFSET Midrange (5 turns from
(Channel A) one end)
Units/Div 100
(Channel A)
VARIABLE CAL
(Channel A)
INVERT push in
(Channel A)
POSITION Midrange
DOT RESPONSE Midrange
(both Channels)
B DELAY Midrange
TRIG OUT switch A
Type 3B4
Position Midrange
Time/Div .2ms
Magnifier unmagnified
Trigger Mode Norm
Triggering Level as required
Source Int
Coupling AC
Slope +
Connect the Type 106 Fast Rise + output signal through
a coaxial cable to the input connector on the sampling head
installed in the Channel A compartment of the Type 3S2.
Set the Repetition Rate Range switch and Multipliers for
1 kHz. Set the + Transition Amplitude control fully clock-
wise.
Adjust the Triggering Level control on the Type 3B4 for
a stable trace. The display will be similar to that of Fig.
2-7A. Notice that with the constant sampling rate of 100
kHz, the upper and lower portions of the square wave dis-
play shows no obvious dots or segments.
Change the Repetition Rate Range switch and the Multi-
plier on the Type 106 for 10kHz. Set the Time/Div switch
on the Type 3B4 to 20 ys/Div. Observe that the display is
segmented. See Fig. 2-7B. This shows the fast sweep rate
limitation of real time sampling. The range of sweep rates
available for use in real time sampling is from the lowest
rate available on the real-time time-base unit to about 0.1
ms/Div. At 0.1 ms/Div about 10 dots per division will be
displayed.

0.2 ms/DIV
Fig. 2-7. Real Time display of (A) 1 kHz and (B) 10 kHz square
wave showing the fast sweep rate limitations.
Real time sampling offers slower sweep rates at the full
bandwidth of the sampling head installed in the Type 3S2.
Other characteristics are reduction of random noise in the
display through smoothing, and DC offset capabilities
matched with good overload recovery.
Useful operating modes for Real Time sampling are CH
A or CH B, DUAL-TRACE, and A+B. Real Time operation
does not permit the A VERT B HORIZ mode. In this mode,
only the Channel A signal will be displayed.
Numerical real time voltage measurements can be made
with the Type 3S2 when used with a readout system such as
Tektronix Type 567 with Type 6RIA and Type 3B2, or Tek-
tronix Type 568 with Type 230 and Type 3B2. Useful modes
of operation for these measurements are: CH A (or CH B),
and DUAL-TRACE.
Gain Adjustment
The GAIN control (a front-panel screwdriver adjustment)
matches the gain of the Type 3S2 vertical output amplifier to
the Oscilloscope CRT deflection factor. The gain should
®
Operating Instructions—Type 352
be checked and adjusted each time the Type 382 is used
with a different oscilloscope.
An accurate known voltage source should be used into the
input connector of the sampling head. The signal source
impedance must be considered when it drives the input of a
50 sampling head.
For 50Q input sampling heads, the Tektronix Type 284
or a precision chopped voltage can be used. The calibrator
output of the indicator oscilloscope (with possibly decreased
accuracy) can be used. Check amplitude specifications of
the calibrator and use only the 50Q output position (usually
0.1 V into 509).
Using Type 284
Using the Type 284 as the signal source to check and/or
adjust the GAIN control of the Type 382 and a 50 sam-
pling head, proceed as follows:
1. Allow the equipment to warm up for a least 5 minutes.
2. Set the controls as follows:
Type 382
Horiz Plug-in Sampling
Compatibility
Display Mode CH B
NORMAL-SMOOTH NORMAL
A and B POSITION Midrange
DC OFFSET Midrange (5 turns from
(both Channels) one end)
Unit/Div 200
(both Channels)
VARIABLE CAL
(both Channels)
INVERT Pushed in
(both Channels)
DOT RESPONSE Midrange
(both Channels)
B DELAY Midrange
TRIG OUT Switch B
Type 372
Horiz Position Midrange
Samples/Div 9 o'clock position
Display Mode Normal
Start Point With Trigger
Sweep rate 200 ns/Div
Range 10 ps
Display Mag x1
Time Magnifier x5
Variable Cal
Time Position Both fully clockwise
Trig Sensitivit For Triggered Display
Y g
Recovery Time Optional
Trigger Polarity =
Trigger Source Ext
2-11

Operating Instructions—Type 3S2
Type 284
Square Wave Amplitude 1.0V
Period 1 ps
Mode Square Wave Output
Lead Time Optional
3. Connect the Square Wave Output signal from the Type
284 to the sampling head input connector in the Channel
B compartment. Use a coaxial cable. Connect the Trigger
Output
signal
from
the
Type
284
to
the
external
Trigger
Input 509 connector on the Type 312 through a coaxial
cable.
A. Adjust the Type 3T2 Trig Sensitivity control for a stable
display. Center the trace on the graticule with the Channel
B POSITION control. Observe a square wave display. If its
amplitude is 5 vertical divisions, the Type 382 GAIN control
is properly set. If the amplitude is not 5 vertical divisions,
adjust the GAIN control with a small screwdriver for 5
vertical divisions.
5. Check Channel A by connecting the signal into the
Sampling Head 50Q input connector installed in the Chan-
nel A compartment. Change the Display Mode switch to
CH A. If the amplitude is not 5 vertical divisions refer to
the Performance and Recalibration section of this Instruc-
tion Manual.
Using Oscilloscope Calibrator
NOTE
It is recommended that 60 Hz oscilloscope cali-
brators
be
used
as
a
signal
source
for
setting
the
Type 3$2 GAIN control only when no other source
is available, and only after verifying the signal
amplitude with accurate measuring equipment.
The following procedure uses the Type 567 or
Type 568 20 kHz Calibrator (500 mV into 50 0,
2%), producing a Type 382 deflection factor
accuracy of £5%.
1. Allow the equipment to warm up for at least 5 minutes.
2. Set the controls as follows:
Type 382
Horiz Plug-In Sampling
Compatibility
Display Mode CH B
NORMAL-SMOOTH NORMAL
A and B POSITION Midrange
DC OFFSET Midrange (5 turns from
(both Channels) one end)
Units /Div 100
(both Channels)
VARIABLE CAL
(both Channels)
INVERT Push In
{both Channels}
DOT RESPONSE Midrange
(both Channels)
2-12
B DELAY Midrange
TRIG OUT Switch B
Type 312
Horiz Position Midrange
Samples/Div 9 o'clock position
Display Mode Normal
Start Point With Trigger
Sweep Rate 10 ps
Range 100 ps
Time Magnifier x)
Variable Cal
Display Mag x1
Time Position Optional
Trig
Sensitivity
For
Triggered
display
Recovery Time Clockwise
Trigger Polarity +
Trigger Source Ext
3.
Apply
the
signal
from
the
indicator
oscilloscope
cali-
brator
500
mV
into
509
connector
to
the
Channel
B
500
input
connector
of
the
sampling
head
installed
in
the
Type
352.
Use
a
coaxial
cable
and
a
BNC
to
GR
adapter
at
the
calibrator
connector.
Connect
the
18
inch
trigger
cable
from
the
Type
382
TRIG
OUT
connector
to
the
Type
372
external
Trigger
Input
50.Q
connector.
Adjust
the
Trig
Sensitivity
control
for
a
stable
square
wave
display.
4.
Center
the
display
with
the
Channel
B
POSITION
con-
trol
and
if
necessary
use
the
DC
OFFSET
control.
5.
With
the
Channel
B
POSITION
and
DC
OFFSET
con-
trols,
align
the
display
with
the
graticule
lines
and
check
for
exactly
5
divisions
of
vertical
deflection.
If
the
amount
of
vertical
deflection
is
not
5
divisions,
adjust
the
GAIN
con-
trol
for
5
divisions.
6.
Check
Channel
A
by
connecting
the
signal
into
the
Sampling
Head
509
input
connector
installed
in
the
Chan-
nel
A
compartment
of
the
Type
3S2.
Set the
TRIG
OUT
switch
to
A.
If
the
amplitude
is
not
5
vertical
divisions
refer
to
Sec-
tion
6,
Performance
Check
and
Recalibration.
Vertical Outputs
A
and
B
signals.
Channel
A
and
Channel
B
composite
signals
are
available
at
the
Vertical
Output
jacks.
The
sig-
nals
at
these
jacks
are
taken
after
the
sampling
process,
and
are,
therefore,
proportional
representations
of
the
display
signal
rather
than
the
input
signals
themselves.
The
output
signal
voltage
follows
the
100kHz
chop
rate
of
the
input
signal
in
real
time
sampling.
The
open
circuit
voltage
at
either
jack
is
200
mV
per
division
of
display
when
the
VARI-
ABLE
controls
are
in
the
CAL
position.
The
maximum
output
is
-4
volts.
The
output
resistance
is
10k.
The
signals
are
taken
prior
to
the
Display
Mode
switch,
and
are
therefore
not
affected
by
the
mode
of
operation.
They
are
affected
only
by
the
respective
Units/Div
switches,
DC
OFFSET
con-
trols,
and
the
NORMAL-SMOOTH
switch.
The
signals
are
not
inverted
by
pulling
the
INVERT
switches,
and
are
not
®

affected by the POSITION controls. Output voltage swing is
not limited to the magnitude displayed on the CRT. This per-
mits a non-sampling type oscilloscope to monitor the facsim-
ile signal the equivalent of 40 CRT divisions when the Units/
Div switch is at 2 (2mV/Div). Since the signals at the Vertical
Output jacks are equivalent time signals, they are useful for
pen recorder applications when the sampling sweep unit
external input is driven by the recorder.
OFFSET Outputs. The two offset monitor jacks permit
accurate measurement of the DC voltage set by the DC
OFFSET controls. Each monitor jack output voltage has a
range of +10 to —10 volts. Unless otherwise specified on
the sampling head front panel the monitor jack output volt-
age is ten times the internal DC Offset voltage. The output
resistance is 10 kQ.
TRIG OUT, SN BO040250-Up. The TRIG OUT connector
makes available an amplified portion of the input signal when
the sampling head contains a trigger pickoff circuit. This
signal can be used for external triggering of equivalent time
sampling sweep units. The voltage output at the TRIG OUT
connector is approximately equal to the input.
Risetime of the trigger pickoff circuit in the sampling heads
Types S-1 and S-2, including the Type 382 Trigger Amplifier
characteristics, is stated in Section 1. No limits are specified
when the TRIG OUT connector drives 1 MQ.
Normal use of this form of internal triggering is to drive
the sampling sweep unit external trigger input 50 2 connector.
The TRIG OUT signal is not useful for externally triggering
a real-time time-base unit.
The TRIG OUT signal is useful to externally trigger a ran-
dom sampling sweep plug-in unit such as the Type 312. To
operate the Type 3T2 in random sampling mode, set the Start
Point switch to Before Trigger. Connect the TRIG OUT sig-
nal to the external Trigger Input 509 connector with the
short coaxial cable provided with the Type 382. Proper dis-
plays triggered from the TRIG OUT signal are easy to obtain
during random sampling when the signal is cyclic square or
sine waves.
NOTE
The Lead Time control in the Type 3T2 may require
clockwise adjustment if you are unable to see the
pulse rise (plus transition) when using the TRIG
OUT signal and random sampling. If a pulse dis-
play can be obtained when the two Type 3T2 Time
Position controls are fully clockwise, the internal
Lead Time control is correctly adjusted. Refer to
the Calibration section of the Type 3T2 Instruction
Manual.
TRIG OUT, SN BO10101 - BO30249. Table 2-1 shows
the output voltage available into 502 and into 1 MQ, to
trigger normal-process (not random process) equivalent time
sampling sweep unit.
No trigger signal risetime limits are specified in Section 1
when the TRIG OUT connector drives ] MQ, but the increase
in gain slows it considerably. Risetime into 1 MQ is approxi-
mately 0.3 us, 10% to 90%, with considerable rounding dur-
ing the last 10%. Open-circuit DC output voltage is about
—2.5 volts. It can swing positive from ground no more than
about +2 volts, but negative from ground to about —12
volts. Thus, when using the TRIG OUT signal into a 1 MOQ
Operating Instructions—Type 3S2
load, severe distortion occurs to the signal when the sam-
pling head input signal is greater than about +1.8 volts.
Fig.
2-8
shows
two
double
exposures
of
random
sampling
attempts
to
measure
a
pulse
risetime
with
a
Type
S-1
Sam-
pling
Head,
while
triggering
the
Type
372
with
the
TRIG
OUT
signal.
The
left
waveform
in
each
photo
indicates
a
false
risetime
and
includes
a
few
holes
in
the
horizontal
portions.
The
right
waveform
in
each
photo
indicates
a
correct
rise-
time.
All
four
exposures
were
made
with
the
Type
372
operat-
ing
in
the
random
sampling
mode.
Triggering
is
by
an
ex-
ternal
pretrigger
signal
for
both
right
waveforms
and
by
the
Type
352
TRIG
OUT
signal
for
both
left
waveforms.
The
obvious
change
in
risetime
and
the
increased
transition
jitter
show
that
the
TRIG
OUT
signal
is
not
always
useful
for
fast
risetime
displays.
Slower
sweep
rates
for
display-
ing
cyclic
signals
produces
no
such
distortions
of
the
CRT
display
when
using
the
TRIG
OUT
signal
and
random
sam-
pling.
TABLE 2-1
TRIG OUT Signal Amplitudes SN BO10101 - BO30249
cignal ey gate TRIG OUT (front panel)
pling Heads into 500 into 1 MQ
+2V 400 mV 42 to —7.6V DC
+1V 200 mV 0 to —5V DC
0.5V 50 mV 1.25 V P-P
: 0.4V 40 mV 1V P-P
03V 30 mV 750 mV P-P
0.2V 20 mV 500 mV P-P
0.1V 10 mV 250 mV P-P
50 mV 5mV 125 mV P-P
20 mV 2mV 50 mV P-P
10 mV TmV 25 mV P-P
BASIC APPLICATIONS
Vertical Deflection Measurements
Vertical displacement of the trace on the CRT is directly
proportional to the signal at the input connector of the
sampling head installed in the Type 382. The amount of
displacement for a given signal can be selected with the
Units/Div switch. To provide sufficient deflection for best
resolution, set the Units/Div switch so the display spans a
large portion of the graticule. Also, when measuring be-
tween points on the display, be sure to measure consistently
from either the bottom, middle, or top of the trace. This
prevents the width of the trace from affecting the measure-
ments.
To make a vertical deflection difference measurement be-
tween two points on the display, proceed as follows:
1. Note the vertical deflection, in graticule divisions, be-
tween the two points on the display. Make sure the VARI-
ABLE control is in the CAL position.
NOTE
The vertical deflection factor is determined by the
Units/Div switch and the value of the units of
measure as stated on the sampling head front
panel. The ratio of the input signal to the resultant
2-13

Operating Instructions—Type 352
| |
ee
|
donne
|
i
Fig. 2-8. Random sampling operation using TRIG OUT signal for
Ext. triggering Type 3T2 (SN BO10101-B040249).
deflection is called the deflection factor. For ex-
ample, with the sampling head unit values stated
as mV/Diy, and the Units/Div switch set to 20, the
vertical deflection factor will be 20 mV/division.
2. Multiply the divisions of vertical deflection by the de-
flection factor, and the external attenuator or probe attenu-
ation factor (if any). The product is the voltage difference
between the two points measured.
For example, suppose you measure 4.4 divisions of de-
flection between two points on the display and the Units/
Div switch is set for 20mV/Div. Multiply 20 millivolts/divi-
sion by 4.4 divisions, the product is 88 millivolts. This is the
voltage difference at the input connector between the two
points on the display. Now assume there is a 10X external
attenuator (probe) between the input connector and the sig-
nal source. To determine the actual signal voltage at the
source, multiply 10 (the attenuation factor of the probe) by
88 millivolts; this product (880 millivolts or 0.88 volts) is the
actual voltage at the signal source.
2-14
It is also possible to measure an instantaneous (or DC)
voltage to ground from the display. This measurement is
accomplished in the same manner, except that with no sig-
nal applied, you must first establish a ground-reference point
on the CRT.
NOTE
To establish the ground reference point be sure
the input connector is either terminated by a 502
resistor or coaxial cable connected to the input.
To do this, trigger the sampling sweep unit with the signal
source and display a trace. Then, position the trace so it
is exactly aligned with one of the gratciule lines. The actual
graticule line you select will be largely determined by the
polarity and amplitude of the applied signal. After estab-
lishing the ground reference, make no further adjustments
with the Position or DC OFFSET controls.
Apply the signal and measure the voltage in the manner
previously described. Make all measurements from the
established ground reference point. Accuracy of this meas-
urement is within —+3%.
If the applied signal has a relatively high DC level, the
ground-reference point and the actual signal may be so far
apart that neither will appear on the CRT. In this case, refer
to the following discussion on "Voltage Measurements Using
the DC Offset Control.”
Voltage Measurements Using the DC
OFFSET Control
Unless otherwise stated on the sampling head front panel,
the DC offset voltage cancels the effects of an applied
DC voltage of up to -£1 volt at the sampling head
input. Also, accurate slideback amplitude measurements of
the applied signal can be obtained by positioning the dis-
play at various -points and measuring the amount of voltage
change at the appropriate OFFSET monitor jack (left hand
jack monitors Channel A, right hand jack monitors Chan-
nel B).
Source resistance for the voltage at the OFFSET monitor
jacks is 10k; therefore, meter loading may be a factor
if other than an infinite-impedance meter is used. The ac-
curacy of the DC offset voltage measurement depends on
the accuracy and the loading effect of the measuring device.
The following measuring devices are recommended, in order
of preference, for monitoring voltage at the OFFSET jacks.
(1) Differential, non-loading DC voltmeter with an ac-
curacy of 0.2% or better. This type of device provides 2%
accuracy of absolute offset voltage measurements. Meas-
urements of small changes in offset voltage can be made
more accurately than 2%.
(2) Vacuum-tube voltmeter with an input impedance of
at least 10 megohms. Accuracy of the VTVM should be as
high as practical.
(3) Zero-center +1 mA milliammeter with as high an ac-
curacy as practical. The milliammeter should be connected
directly between the appropriate OFFSET monitor jack and
ground. When using a milliammeter, 100 microamperes is
equivalent to 1 volt open-circuit at the OFFSET monitor
jack (0.1 volt of actual offset to the signal).