Tektronix S-1 User manual

INSTRUCTION
MAN UAL Serial Number
Tektronix, Inc.
S.W.
Millikan
Way
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Box
500
@
Beaverton,
Oregon
97005
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Phone
644-0161
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Cables:
Tektronix
070-0763-00
468

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SAMPLING HEAD
Fig. 1-1. Type S-1 Sampling Head.

Type S-1
SECTION 1
TYPE S-1 SPECIFICATION
Change information, if any, affecting this section will be found at the
- vear of the manual.
General Information
The Type S-1 Sampling Head is a 50 input, 350 ps rise-
time, plug-in preamplifier for use in some Tektronix 3S-
series sampling units, such as the Type 382 Sampling Unit.
Input characteristics of the sampling system are controlled
by the type of sampling head in use.
The Type S-1 can be installed directly into the Type 382,
or used remotely on an optional 3 foot or 6 foot extender
cable. Vertical deflection factor of the sampling system is
labeled at the top of the Type S-1 as mVOLTS/DIV; the
label refers to the sampling unit Units/Div switch that is
directly above the head.
A portion of the input signal is provided to the Type 352
Sampling Unit for externally triggering a Type 3T2 Random
Sampling Sweep. The Type 3S2 allows selection of the trig-
ger pickoff signal from the Channel A or Channel B sam-
pling head. The selected trigger pickoff signal is returned
to the Type 32 front panel at the Trig Out connector. The
trigger pickoff signal is useful with any sampling sweep unit
for repetitive signals where the triggering event does not
have to be displayed. (Only the Type 312 random process
sampling allows the triggering event to be displayed using
the sampling head trigger pickoff signal.)
Digital Unit Program Connections
The Type S-1 contains connections at its rear that pro-
gram both the decimal and the units lamps of a Type 230
Digital Unit. The S-1 digital! control connections pass through
the Units/Div switch of either the Type 385 or Type 3586
Programmable Sampling Unit, and through the Type 568
Oscilloscope to the Type 230 Digital Unit.
ELECTRICAL CHARACTERISTICS
The following characteristics apply over an ambient tem-
perature range of 0°C to +50°C. These characteristics
apply only after the Type S-1 has been properly mated to
the sampling unit and indicator oscilloscope, and after
sufficient warmup time. For the particular system warmup
requirements, refer to the related amplifier and indicator
oscilloscope instruction manual. {A 5 minute warmup time is
required for Type 3S2-3T2). A procedure for mating the Type
S-1 to the vertical amplifier can be found in the Operating
Instructions section of this manual.
ELECTRICAL CHARACTERISTICS
Characteristics
Performance Requirement
Supplemental Information
Input Resistance 509 within 1%
Measured at DC
Dot Response
Adjustable in the sampling unit to unity
for signals up to 500 mV P-P; when the plus
dot response is adjusted to unity, the minus
dot response will be within 5% of unity,
and vice versa.
Operating Input Voltage Range
+1V to —1V, with < 1V P-P signals.
Step signals greater than 500 mV require
more than one dot to display 100% of the
step transition.
Maximum Input Voltage
-++5 VDC or sine wave of 10 V P-P up to
10 MHz.
Transient Response
Risetime
Pulse Flatness Deviation
Displayed Noise
350 ps or less, 10% to 90%.
< + 05 and — 3% in the first 5 ns after
the step pulse reaches 50%.
< + and — 0.5% after the first 5 ns.
2 mV or less, tangential noise.
Applies when the step pulse is Tektronix
Type 284 Pulse Output signal through a
20 cm airline.
Trace Baseline Vertical Shift with
Trigger Repetition Rate Change.
10 mV or less for trigger rate change from
30 Hz to 50 kHz.
1-1

NOTES

Type S-1
SECTION 2
OPERATING INSTRUCTIONS
Change information, if any, affecting this section will be found at the
- rear of the manual.
General Information
This section provides the basic information required for
operation of the Type S-1 Sampling Head, including instal-
lation and First Time Operation.
The Type S-] completes the circuitry of some Tektronix
sampling units, and controls the input characteristics of
the vertical channel by providing the Strobe Generator, Sam-
pling Bridge, and Preamplifier circuits. Such a sampling unit
is the Type 382, using one or two S-series sampling heads.
A Type 382 and a sampling sweep unit plugged into an
indicator oscilloscope completes the sampling system. A
choice of real or equivalent time sampling is provided by the
type of sweep unit used.
A 502 input resistance allows the use of 50 attenuators
and probes for operation over a wide range of signal volt-
ages,
A portion of the input signal is provided to the sampling
unit. In the Type 382, this signal is selected from Channel A
or B, and returned to the front panel Trig Out connector for
external triggering of sampling sweep units,
Installing the Type S-1 Sampling Head
Fig. 2-1 shows the Type S-1 partially installed into a
Type 382 Sampling Unit with Type 561A Oscilloscope and
Type 3T2 Random Sampling Sweep. The sampling head (or
heads) can be plugged into the sampling unit as shown, or
used remotely on a special extender cable. Three and six
foot extender cables are available. Order the three foot
extender cable by Tektronix Part No. 012-0124-00, or the
six foot extender cable by Tektronix Part No. 012-0125.-00,
Contact your local Tektronix Field Engineer or Representative
for price and availability of these optional accessories.
To insert the Type S-1 into the right or left hand compart-
ments of the sampling unit, proceed as follows:
1. Pull the latch knob (Fig. 2-1) outward from the front
panel (the latch knob will push out normally when the unit
is inserted if the knob is left free to move).
2. Insert the Type S-1 slowly into the compartment, so
the two plastic guides in the compartment engage the S-1.
3. Push the Type S-1 completely into the compartment.
4. Push the latch knob to lock the S-1 in place.
To remove the Type S-1 from the compartment, pull the
latch knob away from the front panel, then pull the unit
from the compartment.
Sampling Head
Loteh knob
Fig. 2-1. Installation information,
To use the Type S-1 on an extender cable, install as fol-
lows:
1. Pull the latch knob located on the head end of the ex-
ender cable outward from the panel (the latch knob will
push out normally when the extender is inserted if the knob
is free to move).
2. Insert the extender cable head end slowly into the
desired compartment in the sampling unit so the two plastic
guides in the compartment engage the unit.
3. Push the head completely into the compartment,
4, Push the latch knob to lock the extender cable head end
in place.
5. Connect the Type S-1 to the other end of the extender
cable in a similar manner, and set the latch knob to hold
it in place.
6. To remove the Type S-1 from the extender cable, pull
the latch knob on the front panel of the Type S-1, and re-
move the unit from the extender cable.
7. To remove the extender cable head from the sampling
unit compartment, pul! the latch knob outward from the front
panel, then pull the unit free.
2-1

Operating Instructions—Type S-1
Mating
The vertical deflection factor labeled by the Type S-1, and
the sampling system loop balance (adjusted by the Bridge
Bal control) must be considered when mating a Type S-1 with
a sampling unit.
The mVOLTS/DIV label on the Type S-1 names the de-
flection factor, units of the sampling unit Units/Div switch
located directly above the label. For example, with the Type
S-1 installed in a Type 382 and the Units/Div switch set at
100, each major division of CRT deflection corresponds to
100 millivolts of input signal (when the Variable control is
in the Cal position). The deflection factor is mated to the
indicator oscilloscope CRT by adjusting the sampling unit
Gain control while the Type S-1 is in Channel B. Refer to the
sampling unit manual for its Gain adjustment. Power supplies
and circuit interconnections are made through the two con-
nectors at the rear of the Type S-1.
Bridge Balance
The Bridge Balance control of the Type S-1 should be ad-
justed whenever the sampling head is changed from one sam-
pling unit to another, or is operated on an extender cable.
Location of the control and details of its adjustment are de-
scribed in First Time Operation which follows.
FIRST TIME OPERATION
The First Time Operation procedure utilizes, in addition
to the Type S-1, a Type 382, Type 561A, and Type 284. The
Type 3T2 Random Sampling Sweep unit is recommended
for use with the Type S-1 because random sampling permits
viewing the signal in advance of the triggering event. Such
trigger lead-time is required by the Type S-1 with the Type
382 to view fast pulses without a pretrigger. The Type 284
is used as a signal source.
Setup Information
1. With the Type 561A Power switch off, insert a Tek-
tronix Type 382 Sampling Unit into the vertical compart-
ment {leff) and a Tektronix Type 3T2 Random Sampling
Sweep into the horizontal plug-in compartment (right).
2. Insert the Type S-1 Sampling Head into Channel A
compartment (left) in the Type 3S2 leaving the latch knob
free to move. Once the S-1 is seated, push the latch to
lock it in place.
3. Set the Intensity control on the Type 561A fully counter-
clockwise.
4, Connect the Type 561A to a power source which meets
its voltage and frequency requirements.
5. Set the Power switch to On. Allow about 5 minutes
warm-up so the units reach operating temperature before
proceeding.
6. For single-trace operation, set the controls as follows:
Type 352
Display Mode CH A
Normal-Smooth Normal
2-2
A and B Position
DC offset
(both channels)
Units /Div
(both Channels)
Variable (both Channels)
Invert
(both Channels}
Dot Response
(both Channels)
B Delay
Horiz Position
Samples/Div
Display Mode
Start Point
Sweep Rate
Range
Display Mag
Time Magnifier
Variable
Midrange
Midrange (5 turns
from one end)
200
Cal
Push in
Midrange
Midrange
Type 312
Midrange
9 o'clock position
Normal
With Trigger
200 ns/Div
10 ps
x1
x5
Cal
Both fully clockwise
Fully clockwise
Time Position
Trig Sensitivity
Recovery Time ~ Optional
Trigger Polarity +
Trigger Source Ext
Type 284
Square Wave Amplitude 1.0 ¥*
Period 1 ps
Mode Square Wave Output
Lead Time Optional
7. Connect the square wave output signal from the Type
284 to the input connector of the Type S-1 through a 500
coaxial cable and a X2 attenuator. Connect the trigger out-
put signal from the Type 284 through a coaxial cable to the
External Input 50 connector on the Type 3712.
8. Advance the Type 561A Intensity control until the free
running trace brilliance is at the desired viewing level.
9. Center the trace on the graticule with the Type 382 A
Position control and/or the DC Offset control. Adjust the
Type 312 Trig Sensitivity control for a stable triggered dis-
play of a two-cycle square wave with an amplitude of about
2.5 divisions.
Adjusting Dot Response
Sequential Sampling
One method of adjusting the dot response to unity is to
use a double or multiple-triggered sweep. This causes each
sample to respond to the full signal amplitude and produce
a display similar fo Fig. 2-2A or B,
10. To obtain a display similar to that of Fig. 2-2A or B,
turn the Type 312 Trig Sensitivity control clockwise into the
‘Used through X2 attenuator for 0.5 V into the Type S-1.

> unity dot response
wy ns/ Div
et ae OAAae BAAD t+ ‘
(B} Double-Triggered, unity dot response
200 mV/Div 200 ns/Div
(C) Properly triggered
Fig. 2-2. Typical display for wnity dot response adjustment in
normal sequential sampling.
>)
Operating Instructions—Type S-1
free run region. Then adjust the Recovery Time control un-
til the desired display appears.
11. Turn the Channel A Dot Response control to obtain a
display showing unity dot response (see Fig. 2-2B). Fig 2-2A
shows greater than unity dot response. This requires counter-
clockwise rotation of the Dot Response control to obtain
unity dot response. The double triggering shown in Fig. 2-2A
and B is useful to adjust the dot response to unity, but should
not be used in making measurements.
12. After the dot response is adjusted to unity, turn the
Trig Sensitivity control counterclockwise into the triggered
region for a stable trace of a properly triggered display
similar to Fig, 2-2C.
Random Sampling
13. Another convenient method of adjusting the dot re-
sponse to unity can be shown with random process sampling.
Change the following controls:
Type 372
Start Point Before Trigger
Time Magnifier < 50
Type 284
Period 100 ns
14. A dot response greater than unity will produce a dis-
play similar to Fig. 2-3A. Dot response deviations from unity
are best observed when the Type 372 Time Magnifier is
set at 20 or X50. Adjust the Type 382 Dot Response con-
trol for a unity dot response display similar to Fig. 2-38.
Bridge Balance Adjustment
15. Connect a bench multimeter set for = 30V full scale
between ground and the Type 352 Channel A Offset jack.
Adjust the Type 382 DC Offset contro! until the multimeter
reads 0 Volts. Increase the meter sensitivity and repeat the
adjustment for greater accuracy.
16, Disconnect the coaxial cable from the Type 284, leav-
ing the other end of the cable connected to the Type 5-1
input connector. Turn the Type 3S2 Trig Sensitivity con-
trol clockwise to free run the trace.
NOTE
Operating the sampling head without the input
connector terminated by a 50 © resistor or coaxial
cable will cause a vertical shift of the zero signal
baseline by a few millivolts. This is caused by the
strobe kickout signal being reflected from the open
input connector, and arriving back at the sampling
bridge while the bridge is conducting. Because of
this phenomena, set the display zero reference
point with the input between the Type S-1 input
between the Type S-1 input and any tunnel-diode
pulse generator or circuit that is sensitive to sig-
nals centering its output circuit.
2-3

Operating Instructions—Type S-1
st
200 mV/ Div
Fig. 2-3. Typical display for unity dot response adjustment in
random sampling operation,
17. Switch the Type 382 Units/Div control throughout
its range, adjusting the Type S-1 Bridge Bal control for a
trace shift of not over one division as the Units/Div control
is switched from one end to the other. See Fig. 2-4 for the
location of the Bridge Bal control. This adjustment must be
made whenever the Type S-1 is shifted from one sampling
unit to another, or operated on a sampling head extender
cable.
GENERAL OPERATING INFORMATION
Input Signal Connection Precautions
Accurate displays of signals containing very fast tran-
sitions or very high frequencies are possible only when the
coupling circuit does not distort the signal. The Type S-1
input resistance is 509 requiring the use of high quality
509 coaxial cables and attenuators between the signal
source and the sampling head input connector. Tektronix,
Inc. offers several special probes that permit the signal
source loading to be less than caused by the 501 input
2-4
Bridge Bal
Adjustment
Fig. 2-4, Bridge Bal Location,
resistance. See your Tektronix Field Engineer or Represent:
ative about such special input coupling devices,
Input Voltage Considerations
Proper displays of various signal amplitudes require spec:
ial attention to the type of time base generation in use
There are also input voltage limits that must be observed
to prevent either display distortion or damage to the Type
S-1.
For greater details on coupling of high frequency input
signals, and on precautions to be observed, refer to the sam
pling unit Instruction Manual supplied with your sampling
instruments,
Maximum input signal voltage is an important consider-
ation in any sampling system. Signals greater than -+1 or
1 volt generally will not permit a valid display. Thus any
signals of greater. amplitude should be attenuated in some
manner before being applied to the Type S-1 input con-
nector, Maximum input voltage without damage to the in-
put termination resistor is -+-5 or —5 volts DC, or 10 volts
peak to peak sine wave signals in the frequency domain of
10 MHz or below.
Where unity dot response is required, accurate displays
are possible to achieve only when the input amplitude and
the time base generator mode are both considered, The two
time base generation modes are (1) normal process sampling,
where each dot is displayed in sequence across the CRT,
and (2) random process sampling where the dots are not
necessarily displayed in a sequence that progresses uniformly
across the CRT. (The Type 3T2 Random Sampling Sweep unit
presents random process sampling displays in a controlled se
quence very similar to normal process sampling when the
Time Magnifier switch is at X1 or X2 and the trigger sig-
nal repetitfon rate is uniform.) The random process dot se-