Tektronix 2B67 Time Base (2MHz) (1969)/h3>

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BAMA 2B67 Free Manual and Schematic Download Site
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Operating Instructions
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$225 (1969)
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  • 1 µs/div to 5 s/div Calibrated Time Base
  • 5X Magnifier
  • Triggering to 2 MHz
  • Single Sweep Operation



    The Tektronix Type 2B67 Time-Base plug-in unit provides time-base deflection for Tektronix 560-Series oscilloscopes. It provides a triggered or free-running sweep, calibrated or continuously variable. The sweep may be triggered internally from either the vertical signal or the power line, or externally. Either repetitive or single-sweep operation may be selected. The Type 2B67 is normally used to provide the horizontal sweep for 560-Series oscilloscopes, but may be used to provide a vertical sweep, if desired. The unit is also provided with an input for external signals.

    Sweep Rates
    1 microsecond to 5 seconds per divisoin in 21 calibrated steps. An uncalibrated control provides continuously variable sweep rates to about 3 times the step-switch setting. Calibrated sweep rates are within 3% of step-switch setting; magnified rates are with 5%.

    Provides a 5-times expansion of the center 2 divisions of display, and extends the fastest sweep rate to 0.2 microsecond/division with 1% linearity after the first four divisions.

    Triggering Modes
    Internal, External, and Line. Trigger coupling may be selected from AC slow, AC fast, and DC and triggering level and polarity are continuously adjustable. Triggering level may be set to provide free-running or automatically triggered sweeps.
        Triggering Signal Requirements
    Internal Triggering: A signal producing two minor divisions of deflection.
    External Triggering: A signal from 0.5 volt at dc to 2.0 volts at 2 mc. Sweep will trigger on larger signals, but LEVEL control limit is ±10 volts.

    Single Sweep
    Single sweep may be selected, allowing sweep to operate only after manual reset for either triggered or free-running operation.

    External Signal Input
    Bandpass: Dc to about 750 kc.
    Sensitivity: About 1 volt/division.

    Aluminum-alloy chassis.

    Photo-etched anodized aluminum front panel.

    above excerpts from Tektronix Type 2B67 Instruction Manual


    In the following instructions it is assumed that the Type 2B67 is inserted in the right-hand (X-axis) opening of the oscilloscope, thereby providing horizontal deflection of the trace. If it is inserted in the left-hand (Y-axis) opening of the oscilloscope it will provide vertical deflection and the instructions must be interpreted accordingly. It is further assumed that there is an amplifier plug-in in the left-hand opening of the oscilloscope.

    Front-Panel Controls and Connectors

    POSITION   Controls horizontal position of the crt display.
    CALIBRATIONAdjusts amplifier gain to compensate for differences in crt deflection factors.
    TIME/DIV.Selects the desired sweep rate from a choice of 21 calibrated rates. In addition, an EXT. INPUT position is provided for connecting external signals.
    VARIABLEProvides a continuous range of sweep rates between the fixed steps of the TIME/DIV. switch. (The sweep rates are calibrated only when the VARIABLE control is set fully clockwise to the CALIBRATED position.) By pulling the VARIABLE control out, 5X magnification of the sweep is obtained.
    UNCAL. LampLights when VARIABLE control is off CALIBRATED position to warn operator he is using an uncalibrated sweep rate.
    EXT. INPUTInput connector for application of external signals (TIME/DIV. switch must be in the EXT. INPUT position).
    EXT. TRIG.Input connector for external triggering signal.
    STABILITYSets voltage level at input to Time-Base Generator to permit proper triggering by Time-Base Trigger.
    LEVELSelects the voltage level on the triggering signal at which the sweep is triggered. This control also selects automatic triggering (AUTO. position) or allows the sweep to free run (FREE RUN position).
    SLOPESelects whether the sweep starts on the positive-going portion (+ Slope) or negative-going portion (- Slope) of the triggering signal.
    COUPLINGSelects AC Slow, AC Fast, or DC coupling of trigger input.
    SOURCESelects the source of the triggering signal. INT. signal is obtained from the vertical plug-in unit. LINE signal triggers units at line frequency, and EXT. requires an externally-supplied signal.
    MODESelects either normal triggered sweep or single sweep which must be reset with switch.
    READY LampLights when sweep is reset and ready to be triggered in the SINGLE SWEEP position of the MODE switch.

    Sweep Triggering

    To obtain a stable display, it is necessary to begin each sweep by reference to the input signal, or by some signal which bears a fixed time relationship to the input signal. The following instructions tell you how to select and use the proper triggering signal for various applications.

    Selecting the Triggering Source

    For most applications the sweep can be triggered by the input signal. The only requirement is that the display amplitude must be at least two minor graticule divisions. To trigger the sweep from the displayed signal, set the SOURCE switch to the INT. position.

    Sometimes it is best to trigger the sweep with an external signal. To use an external signal for triggering the sweep, connect the trigger signal to the EXT. TRIG. connector and set the SOURCE switch to EXT. External triggering is especially useful where signals are measured from several different places within a device. By using external triggering, it is not necessary to reset the triggering controls each time a new waveform is shown. External triggering may also be used with a dual-trace amplifier in the alternate mode to show the proper time relationship between the two displayed signals. For a stable display, the external triggering signal should have an amplitude of at least one volt, peak-to-peak, and bear a fixed time relationship to the displayed signal.

    To observe a signal that bears a fixed time relationship to the line frequency, you may wish to trigger the sweep from the line-frequency signal. To do this, place the SOURCE switch to the LINE position.

    Selecting the Trigger coupling

    For most recurrent waveforms satisfactory triggering will be obtained with the COUPLING switch in the AC SLOW position. However, when triggering from very low frequencies (below about 16 Hz.), greater triggering sensitivity will be obtained with the COUPLING switch in the DC position. The AC FAST position of the COUPLING switch should be used to trigger only on the high-frequency component of a signal containing both high- and low-frequency components, and when using a dual-trace plug-in unit in the alternate mode with internal triggering.

    With ac coupling, the sweep is triggered when the signal reaches a given amplitude with respect to its dc average. With dc coupling, the sweep is triggered when the signal reaches a definite dc amplitude.

    Selecting the Trigger Slope

    When the SLOPE switch is in the + position, the sweep is triggered on the positive slope of the triggering signal. When the SLOPE switfh is in the - position, the sweep is triggered on the negative slope of the triggering signal.

    Selecting the Trigger Level

    The LEVEL control determines the instantaneous voltage level (ac or dc, depending on the setting of the COUPLING switch) on the triggering signal at which the sweep is triggered. With the SLOPE switch in the + position, adjustment of the LEVEL control makes it possible to trigger the sweep at virtually any point on the positive slope of the triggering signal. Likewise, with the SLOPE switch in the - position, adjustment of the LEVEL control makes it possible to trigger the sweep at virtually any point on the negative slope.

    At the extreme ends of its range, the LEVEL control activates the FREE RUN and AUTO switches. The effects of these switches are discussed in the following paragraphs.

    Automatic Mode of Operation

    With the LEVEL control set to AUTO., the Type 2B67 will trigger automatically on most signals. In this mode the triggering signal is ac-coupled, and the triggering level is automatically set. Normal amplitude internal or external triggering signals will trigger the sweep. In the absence of a triggering signal, the sweep triggers automatically at about a 50 Hz. rate.

    Free-Running Mode of Operation

    Setting the LEVEL control to FREE RUN produces a free-running sweep, independent of any trigger signal. Frequency of the free-rnning sweep depends on the setting of the TIME/DIV. switch. A free-running trace is useful as a base line for making dc measurements.

    Single Sweep Operation

    The usual repetitive display is best for most applications. however, in applications where the displayed waveform is not repetitive in amplitude, slope, or time, a repetitive sweep produces a jumbled display. When oberving a waveform of this type, it is usually advantageous to use a single-sweep presentation.

    The Type 2B67 provides single-sweep operation so information can be recorded without confusion that could result from multiple traces. Single-sweep operation is selected by placing the MODE switch to SINGLE SwEEP.

    When the LEVEL control is set to FREE RUN, a single sweep occurs immediately each time the MODE switch is pressed to the RESET position and released. With the LEVEL control set for triggered sweep, the single sweep does not occur until the first triggering signal after momentarily pressing the switch to RESET. The READY lamp lights after the sweep has been reset, indicating that the sweep is ready to be triggered. When a trigger signal occurs, the sweep runs, the READY light goes out, and the sweep waits until the switch is again pressed to RESET and released. Each time the sweep runs and the switch is pressed to RESET, the procedure is repeated.

    When operating the Type 2B67 in the single-sweep mode, the apparent brilliance of the trace will be less than that during repetitive sweep operation. This is because the crt phosphor persistence makes a repetitive sweep look brighter than each individual sweep. In an attempt to increase the single-sweep brilliance you may increase the intensity too much. There is a point of maximum intensity above which a proper focus cannot be obtained. To get the best resolution during single-seep work, first be sure that the intensity is within the range where a small spot can be sharply focused.

    Magnification of the Sweep

    Any portion of the trace can be expanded horizontally five times by pulling the VARIABLE control knob out. To expand any portion of the trace, move the portion to be expanded to the center of the graticule with the POSITION control, and pull the VARIABLE control knob out.

    To determine the true sweep rate in magnified sweep operation, divide the setting of the TIME/DIV. switch by five. (The VARIABLE control must be turned fully clockwise.)

    above excerpts from Tektronix Type 2B67 Instruction Manual

    1-2366-113Knob, Small Charcoal, POSITION
    1-6366-144Knob, Large Charcoal, TIME/DIV.
    1-5366-038Knob, SmallRed, VARIABLE
    1-4366-113Knob, Small Charcoal, LEVEL
    SW341311-166(w/ R160Y) Pull Switch 5X MAG
    R323311-1112x50K var (POSITION)
    SW160260-352Switch, unwired, TIME/DIV, CALIBRATED
    R160Y (SW341)311-16620K var (VARIABLE)
    SW124260-501Switch, lever, MODE
    R334311-19110K var (CALIBRATION)
    R111311-11215K var (STABILITY)
    SW20260-447Switch, slide, TRIGGERING SLOPE
    SW10260-448Switch, slide, TRIGGERING COUPLING
    SW5260-450Switch, slide, TRIGGERING SOURCE
    SW17 (w/R17)260-353Switch, LEVEL
    R17311-206250K var (LEVEL)