3B4: Difference between revisions

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* [http://w140.com/3b4.pdf Tektronix 3B4 Manual (PDF)]
* [http://w140.com/3b4.pdf Tektronix 3B4 Manual (PDF)]
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The '''Tektronix Type 3B4''' is a timebase plug-in for [[560-series scopes]]. It was introduced in 1964.
The '''Tektronix Type 3B4''' is a timebase plug-in for [[560-series scopes]].
It was introduced in 1964.


It was intended primarily for use with the [[561A]], but works fine in other 560-series scopes. The 3B4 is unusual in having an explicit "FREE RUN" mode.   
It was intended primarily for use with the [[561A]], but works fine in other 560-series scopes.
The 3B4 is unusual in having an explicit "FREE RUN" mode.   


In the triggered modes, the [[tunnel diodes|tunnel diode]]-based triggering is rated to work to 20 MHz. The vertical bandwidth of typical 560-series (non-sampling) scopes is about 10 MHz, so 20 MHz is adequate.   
In the triggered modes, the [[tunnel diodes|tunnel diode]]-based triggering is rated to work to 20 MHz.
The vertical bandwidth of typical 560-series (non-sampling) scopes is about 10 MHz, so 20 MHz is adequate.   


Triggering is done with a [[TD3A]] 4.7 mA tunnel diode. The trigger input is amplified and buffered by a [[6DJ8]]-based differential amplifier driving a common-emitter [[2N964]] germanium PNP transistor whose collector current switches the tunnel diode.
Triggering is done with a [[TD3A]] 4.7 mA tunnel diode.
The trigger input is amplified and buffered by a [[6DJ8]]-based differential amplifier driving a common-emitter
[[2N964]] germanium PNP transistor whose collector current switches the tunnel diode.


The [[283]] Real Time adapter enables real-time sweeps with a 3B4.
The [[283]] Real Time adapter enables real-time sweeps with a 3B4.

Revision as of 17:37, 3 February 2018

Template:Plugin Sidebar 2 The Tektronix Type 3B4 is a timebase plug-in for 560-series scopes. It was introduced in 1964.

It was intended primarily for use with the 561A, but works fine in other 560-series scopes. The 3B4 is unusual in having an explicit "FREE RUN" mode.

In the triggered modes, the tunnel diode-based triggering is rated to work to 20 MHz. The vertical bandwidth of typical 560-series (non-sampling) scopes is about 10 MHz, so 20 MHz is adequate.

Triggering is done with a TD3A 4.7 mA tunnel diode. The trigger input is amplified and buffered by a 6DJ8-based differential amplifier driving a common-emitter 2N964 germanium PNP transistor whose collector current switches the tunnel diode.

The 283 Real Time adapter enables real-time sweeps with a 3B4.

Key Specifications

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