From TekWiki
Jump to: navigation, search
Tektronix 3A8
Operational amplifier
3A8 front view

Compatible with 560-series scopes

Produced from 1965 to 1972

Manuals – Specifications – Links – Pictures

The Tektronix 3A8 is an operational amplifier plug-in for 560-series scopes. It was designed by Roy Hayes.


Display Amplifier Bandwidth DC to 3.5 MHz
Display Amplifier Sensitivity 20 mV/cm to 10 V/cm
Opamp Gain Bandwidth Product ≥10 MHz
Opamp DC Open Loop Gain ≥ 10,000
Opamp Output ≥ ± 25 V driving ≥ 7.5 mA (including feedback current)
Opamp Features Input and feedback resistances and capacitances are separately switch selectable to provide a variety of opamp functions.

External components can be substituted by way of front panel banana sockets which also accept special purpose adapters (see Accessories).


The 3A8 contains one vertical display amplifier and two operational amplifiers.

The 3A8 display amplifier can accept inputs from the output of either operational amplifier or from an external input. The input can be AC or DC coupled and can be inverted if desired. It has several transistors plus three 9-pin miniature vacuum tubes: an 8416 and two 6KV8s.

Each 3A8 operational amplifier can accept external inputs and has external as well as internal outputs. Each operational amplifier has a number of transistors plus three Nuvistors: a 6CW4 and a selected pair of 7586s.


013-0049-01 Standard Shielded Cover (two supplied with each plugin)
013-0048-01 Terminal Adapter Assembly (empty box for user chosen components)
013-0081-00 Compensating Adapter
013-0068-00 Gating Adapter
013-0086-00 Leakage Current Adapter
013-0067-00 Logarithmic Amplifier Adapter

Calibration Fixtures

067-0507-00 Grid Current Checker