Tektronix B 20 MHz Wide-Band High-Gain Plug-In (1956)

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Quick Specifications / Photos
Detailed Specifications
Operating Instructions
Misc. Part Numbers

Samples of e-Bay Prices
Orig CostLow BidHigh Bidaverage
$125 (1956)
$170 (1969)
no bids (asked $9.99 + $18 ship) 5/5/06 #7614646876 phatdude43 (untested)
$9.99 (+~$13 ship) 2/3/008 #120215051629 sir_dan (2 bids $9.99 start) (w/ tubes-"working condition")
$9.00 (+? ship) 2/12/08 #270209502937 healingmass (1 bid) (untested - has all tubes)
$9.99 (+~$14 ship + $4 handling) 5/26/09 #160336243576 forrest62 (1 bid) (untested-seems complete)

  • Bandwidth - Up to 20 MHz
  • Risetime - down to .018μsec
  • .005 V/CM to 20 V/CM


    Tektronix Type B Plug-In.

    The Type B Plug-In Unit is a wide-band, high gain calibrated preamp, designed for use with Tektronix Type 530-, 540- and 550 Series Oscilloscopes. The unit contains a dc amplifier similar to that in the Type A Unit preceded by a wide-band ac amplifier. Type B Specifications
    Used With
    Transient Response
    .05 v to 20 v/vm/td>
    Transient Response
    .005 v to .02 v/cm
     RisetimePass Band*RisetimePass Band*
    541, 541A, 543
    545, 545A, 555
    .018μsecDC - 20 MHz
    2 Hz - 20 MHz ac
    .03μsec3 Hz - 12 MHz
    551.02μsecDC - 19 MHz.03μsec3 Hz - 12 MHz
    531, 531A, 533,
    535, 535A
    .035μsecDC - 10 MHz
    2 Hz - 10 MHz ac
    .04μsec3 Hz - 9 MHz
    532.07μsecDC - 5 MHz
    2 Hz - 5 MHz AC
    .07μsec3 Hz - 5 MHz
    * Down not more than 3 db at indicated limits.

    Plug-In Amplifier

    Risetime at .05 to 20 v/cm - .01 μsec.

    Risetime at .005 to .02 v/cm - .03 μsec.

    Deflection Factor:

    .05 v/cm to 50 v/cm dc

    .005 v/cm to 50 v/cm ac.

    Signal Inputs - Two signal inputs with more than 60 db isolation.

    Step Attenuator:

    Twelve positions, calibrated, from .005 v/cm to 20 v/cm, accurate within 3% when set on any one step.

    Maximum Allowable Combined DC and Peak AC

    Input Voltage - 600 V.

    Input Impedance: - 1 megohm, 47 pf.

    With P410 probe - 10 megohms, 11 pf.

    With P510 probe - 10 megohms, 15 pf.

    With P6000 probe - 10 megohms, 11.5 pf - 14.5 pf.

    Separate UHF coax connectors to the preamp by way of the INPUT SELECTOR switch.
    INPUT SELECTORFour-position switch to select either of the two inputs and the type of input coupling.
    DC BALScrewdriver control to adjust the amplifier balance so the trace does not shift as the VARIABLE control is rotated.
    VERTICAL POSITIONControl to position the trace vertically.
    GAIN ADJ. 1Screqdriver control to set the basic gain of the dc amplifier.
    GAIN ADJ. 2Screwdriver control to set the gain of the ac amplifier to 10.
    VOLTS/CMTwelve-position switch to select the calibrated vertical-deflection sensitivities.
    VARIABLEControl to vary the gain over a range of about 2 ½ to 1.

    above excerpts from Tektronix Type B Plug-In Instruction Manual

    Input Connections

    Two cables can be connected to the preamp at once. You can then select the signal on either cable with the INPUT SELECTOR switch. However, if one signal is very much larger than the other, some crosstalk may occur and the cable having the strong signal should be disconnected.


    It is sometimes unnecessary or undesirable to display the dc level of the waveform. In the two AC positions of the INPUT SELECTOR switch, a capacitor in series with the input blocks the dc component of the waveform so that only the ac component is displayed.

    Deflection Sensitivity

    The VOLTS/CM switch inserts frequency-compensated attenuators ahead of the amplifier. The VARIABLE control provides continuous adjustment of the deflection sensitivity between the values indicated by the VOLTS/CM switch.

    The VARIABLE control must be clockwise to CALIBRATED position for the sensitivity to be as indicated by the VOLTS/CM control.

    Gain Adjustment

    Aging of tubes will affect the gain of the plug-in unit. After the plug-in unit has been in use for a period of time the gain adjustment should be checked. Display a calibrator waveform of 0.2 volts peak to peak with the VOLTS/CM switch in the .05 position. Adjust the GAIN ADJ. 1 control until the displayed waveform is four graticule divisions in amplitude. Be sure the VARIABLE control is turned clockwise to the CALIBRATED position before making this adjustment.

    Now set the calibrator at 20 MILLIVOLTS and turn the VOLTS/CM switch to .005. Adjust the GAIN ADJ. 2 control until the amplitude of the displayed waveform is four divisions.

    DC Balance Adjustment

    The need for adjustment of the DC BAL control is indicated by a shift in the position of the trace as the VARIABLE control is rotated. This is caused by tube aging and the resultant shift in operating potentials. This adjustment should be made after the GAIN ADJ. control is set. Rotate the VARIABLE control back and forth and adjust the DC BAL. control until the trace position is no longer affected by rotation of the VARIABLE control.

    Positioning Adjustment

    The VERT POS RANGE control balances the dc output level so the full range of the front-panel control can be utilized. The VERT POS RANGE control is located at the left to the rear of the plug-in unit and is accessible when the left side panel is removed. Center the VERTICAL POSITION control. Adjust the VERT POS RANGE control to cent the trace on the screen.

    above excerpts from Tektronix Type B Plug-In Instruction Manual
    366-042Knob, Large Black, 1/4" hole part way VARIABLE
    366-042Knob, Large Black, 1/4" hole part way VERTICAL POSITION
    366-040Knob, Large Black, 1/4" hole thru VOLTS/CM
    366-038Knob, Small Red VARIABLE
    SW3022260-0812 wafer, 4 pos rotary INPUT SELECTOR
    R3512311-280780 ohm Pot VARIABLE
    R3712311-0282 x 100K 2W Pot VERTICAL POSITION
    SW3142260-1546 wafer, 12 pos, rotary VOLTS/CM (serial X3301 up)
    SW3202260-0805 wafer, 11 pos, rotary VOLTS/CM (serial 101-3300X)
    V4102154-040/18712AU6/6DJ8 (6DJ8 for serial # > 3300)