3B1
The Tektronix 3B1 is a time-base plug-in introduced in 1962 for 560-series scopes. 10 MHz is is the maximum trigger frequency. The calibrated sweep rates go from 1 s/Div to 500 ns/Div.
There is a switch that enables 5 × horizontal magnification, which makes the fastest sweep 100 ns/Div. The 3B1 has a delayed sweep and a regular sweep.
Key Specifications
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Internals
The 3B1 uses vacuum tubes, bipolar junction transistors, and tunnel diodes.
The trigger input goes through the int/ext switch and then the AC/DC coupling switch, and then a 7895 cathode follower. The output of the cathode follower drives one base of a 2N2207 PNP differential amplifier which has a tunnel diode in the collector load. The tunnel diode generates pulses when it switches back and forth between its two stable voltages, which are capacitively coupled to a 2N2501 NPN common emitter amplifier.
The delay pickoff circuit is a 6DJ8 differential amplifier that compares the sweep ramp voltage with a knob-controlled DC voltage which determines the point where the delayed trigger starts. The DC voltage is made by a ZZ1000 80 V reference passed through a potentiometer-variable voltage divider.
When the sweep ramp exceeds the control voltage, a 2.2 mA tunnel diode in the plate load of the differential amplifier switches state.
Pictures
Some Parts Used in the 3B1
Page | Class | Description | Used in |
---|---|---|---|
6DJ8 | Vacuum Tube (Dual Triode) | dual triode | 80 • 132 • 161 • 310A • 316 • 317 • 3A75 • 502 • 502A • 503 • 504 • 515 • 516 • 519 • 526 • 529 • RM529 • 533 • 535 • 536 • 543 • 544 • 545 • 545A • 545B • 546 • 547 • 549 • 555 • 556 • 565 • 581 • 581A • 585 • 585A • 661 • 2A60 • 63 • 2A63 • 3A7 • 3A8 • 1121 • 1A4 • 67 • 81 • 82 • 86 • 3B1 • 3B4 • 1S1 • B • O • W • Z • Telequipment S32A • Telequipment D52 • Telequipment TD51 • Telequipment S52 • Telequipment S51 • Telequipment Type A |
7895 | Vacuum Tube (Triode) | Nuvistor triode | 3B1 • 3B3 |
ZZ1000 | Gas Discharge Tube (Voltage regulator) | 81 V voltage reference | 129 • 3B1 • 422 |