View source for 3B1

{{Plugin Sidebar 2 |
title=Tektronix 3B1 |
summary=10 MHz time base |
image=3b1 front.jpg |
caption=Tektronix 3B1 front |
introduced=1962 |
discontinued=(?) |
series=[[560-series scopes]] |
manuals=
* [http://w140.com/tek_3b1.pdf Tektronix 3B1 Manual (PDF)]
* [[Media:070-449.pdf|3B1 Performance Check Out]]
}}
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.  

{{MissingSpecs}}

==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==
<gallery>
3b1 front.jpg|Front 
3b1 left.jpg|Left
3b1 right.jpg|Right
3b1 bottom.jpg|Bottom
3b1 top.jpg|Top
3b1 cat3.jpg|In 1965 Catalog
3b1 normal trigger.png|Normal trigger circuit
3b1 delayed trigger.png|Delayed trigger circuit
3b1 delay pickoff.png|Delay pickoff circuit
3b1 normal sweep.png|Normal sweep circuit
3b1 delayed sweep.png|Delayed sweep circuit
3b1 horizontal amp.png|Horizontal amp circuit
</gallery>

[[Category:560 series plugins]]