The Tektronix 3A1S is a vertical plug-in for the 561S.
|Deflection||from 10 mV/Div to 10 V/Div (in a 561S)|
|Rise time||14 ns|
|Input impedance||1 MΩ // 47 pF|
The input signal passes through a compensated attenuator switch and then into a 7586 cathode-follower biased with 2 mA plate current.
The gain stages use a mix of transistors and output stage driving the deflection plates is a transistor/pentode cascode circuit with T-coil loading.
The 3A1S is built in traditional ceramic-strip construction.