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Tektronix Type 3A2
Dual trace amplifier plugin
Type 3A2 front view

Compatible with 560-series scopes

Produced from 1964 to 1974

Manuals – Specifications – Links – Pictures

The Tektronix Type 3A2 is a dual-trace amplifier plug-in introduced in 1963 for 560-series scopes. It was designed for compatibility with the digital unit in the 567, e.g, the 6R1 or 6R1A.


Bandwidth 500 kHz
Input impedance 1 MΩ // 47 pF
Deflection factor 10 mV/div to 25 V/div


The input signal passes through compensated attenuators and then into a 12AT7 cathode-follower stage. Channel switching in ALTERNATE mode is done using diodes. The output stage that drives the vertical deflection plates of the scope uses a pair of 6BA8 pentodes.

The "CHOP" mode of the 3A2 switches back and forth between the two inputs at a rate of a few kilohertz. The signal that causes the switching is generated by a relaxation oscillator formed using a capacitor and a pair of 152-108 Shockley diodes, D385 and D386.