Tektronix 3S1 Wide-Band Sampling Unit 1 GHz (1969)

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Tektronix Catalog CostLow BidHigh Bidaverage
$1195 (1969)
$1500 (1971)

Use with P6035 Probe
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    General Information

    The Type 3S1 Dual-Trace Sampling Unit is a 50 Ω input dual-channel vertical plug-in unit designed for operation in any of the Tektronix 560-Series Oscilloscopes except the Type 560 or Type 561 (It will operate in the Type 561A). The Type 3S1 operates with either sampling or conventional horizontal plug-in units to take full advantage of its DC to 1000 MHz bandwidth. Sampling horizontal units include the Types 3T2, 3T4 and 3T77A. The Type 3S1 unity dot response permits random ssampling displays without overshoot or undershoot for full graticule signal changes in one dot. Conventional horizontal units include the Types 2B67, 3B1, 3B3, 3B4 and 3B5 non-digital time bases, and the Type 3B2 Analog/Digital Time Base Unit. The Type 3S1 provides all the vertical information needed for voltage measurements by either Tektronix digital readout system, the Type 567-Type 6R1A, or the Type 568-Type 230.

    The Type 3S1 Dual-Trace Sampling Unit is designed to operate within the Type 561A, RM561A, 564, RM564, 567, RM567, 568 and R568 Oscilloscope main frames. Digital readout is available only when the Type 3S1 is oin a Type 567, RM567, 568 or R568 Oscilloscope main frame. Operation with either conventional or sampling time base units is a new feature of the Type 3S1, allowing either analog displays, or digital readout for both real-time and equivalent time sampling.

    Each of the two channels has its own trigger take-off circuit, signal delay line, deflection factor and positioning controls. Sampled signals are presented to both the Oscilloscope CRT and to front panel connectors for external use with auxiliary equipment such as pen recorders. The two channels operate either individually or in one of three combined modes: Dual Tracs, A + B (Algebraic addition), or A VERT/B HORIZ (X-Y).


    Digital Unit Compatibility

    The Type 3S1 is compatible for operation with all Type 230 Digital Units and all Type 6R1A Digital Units. It is compatible with all Type 6R1 Digital Units s/n 694 and up. Type 6R1 Digital Units s/n 101 - 694 (with exceptions beginning at s/n 391) require the installation of Tektronix Modification Kit 040-0342-00 when operated with a Type 3S1.

    The following characteristics apply over an ambient temperature range of 0° C to + 50° C. These characteristics apply only after the Type 3S1 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 instructions manual.


    DC OFFSET Internal Voltage RangeTrace baseline vertical shift with trigger repetition rate change
    CharacteristicsPerformance RequirementSupplemental Information
    Transient Response Risetime≤ 350 ps, 10% to 90% of step pulse signal
    Aberration and Tilt≤ + and - 2% in the first 5 ns after step pulse reaches 100%
    ≤ + and - 1% after the first 5 ns
    Applies when pulse generator is a terminated Tektronix Type 281 TDR Pulser.
    Deflection Factors
    mVOLTS/DIV Switch Range
    2 mV to 200 mV in 7 steps in a 1-2-5 sequence.
    AccuracyWithin ±3% with INVERT/NORM switch at NORM.
    Within ±5% with INVERT/NORM switch at INVERT.
    mV/div VARIABLE Range≤0.7:1 reduction in deflection when control is turned CCW from CAL position, and ≥2.5:1 increase in deflection when control is turned CW from CAL position.
    Input resistance50Ω, ±1Ω.Measured at DC.
    Input Signal
    Dynamic Range
    Safe Input Overload

    + and - 2 volts from ground.
    + and - 5 volts from ground.
    ≥ + and - 1 volt.
    Tangential noise≤ 2mV at unity dot response.
    ≤ 1 mV when smoothed.
    When making a visual noise reading from the sampling display, the eye interprets a noise value which is neither the RMS nor the peak to peak value. Most observers agree that the displayed noise value is approximately 3 times the RMS value. Thus it is convenient to define "tangential noise" as exactly 3 times the RMS value. The tangential noise value so defined contains about 90% of the trace dots, representing what most people see in a display containing noise.
    Voltage Interchannel crosstalk≤ 1% P-P when input signal is a step voltage with ≤ 80ps risetime.Unused channel, in which crosstalk is ovserved, terminated in 50Ω.
    Co-channel Time Coincidence≤ ps.
    Dot Response


    Adjustable (at front panel) to Unity.
    ≤0.3:1 when NORMAL is adjusted to Unity.
    Full graticule display change in one dot without overshoot or undershoot.
    First dot of 100% step display moves ≤0.3 the full amount it would move at Unity dot response.
    ≤10 mV for trigger rate change from 30 Hz to 100 kHz.Timing Unit externally triggered.
    Dot slashVertical dot drift is ≤0.1 div when timing unit is triggered at 20 Hz.
    FREE RUN Frequency100 kHz ± 5%.
    OFFSET OUT Voltage
    Accuracy (Referred to input)

    ≥ + and - 10 volts.
    10X the DC offset, ± 2%
    Controlled by associated channel DC OFFSET ± 1 V control.
    A OUT, B OUT
    Accuracy (Referred to input)
    Accuracy (Referred to CRT)
    (AC signal peak to peak inout in volts)
    [200 ÷ mV/div setting] = A OUT or B OUT in volts ±2%.
    200 mV/displayed div ±3% in NORM
    200 mV/displayed div ±5% in INVERT
    Maximum output voltage ± 4 V. Source Resistance 10 kΩ ±0.5%.
    Vertical Signal Accuracy to Digital Unit1 V per division of CRT vertical dot change, ±3%.
    Internal Trigger Pickoff Signal Amplitude≥0.12 X Input signal voltage.Checked with INTERNAL TRIGGER Switch at OFF, due to variations in timing units.
    DOT RESPONSE Controls Range≤0.95 to ≥1.05 of unity dot response.
    VERT GAIN Control Range≤9 to ≥13 Voltage gain..
    Power Supplies
    +12.2 V
    +100 V
    +12.2 volts ±1%. Not over 2 mV P-P 120 Hz ripple.
    +100 volts ±5%. Not over 10 mV P-P 120 Hz ripple.

    Temperature -- -40° C to +65° C.
    Altitude -- To 50,000 feet.

    Operating Temperature -- 0° C to +50° C
    Operating Altitude -- To 15,000 feet.


    Approximate dimensions including knobs and connectors.
    Dimensions --Height
    6 1/3 inches
    44 5/16 inches
    14 1/4 inches
    Construction--Aluminum alloy chassis with epoxy laminated circuit boards, Front panel is anodized aluminum.

    Above excerpt from Tektronix Type 3S1 Dual-Trace Sampling Unit Instruction Manual