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Tektronix 7A42
350 MHz four-channel logic triggered amplifier
7A42 front view

Compatible with 7000-series scopes

Produced from 1984 to 1990

Manuals – Specifications – Links – Pictures

The Tektronix 7A42 is a four-channel 350 MHz plug-in for 7000-series scopes.

It was specifically designed for logic signals (TTL, ECL, CMOS) and supports triggering based on Boolean conditions of the four inputs.

A fifth trace, "Trigger View", displays the trigger function output or external clock input.

The input V/Div setting can only be seen in the mainframe's readout.

Tektronix recommended the P6131, 300 MHz, 10 MΩ ×10 probe, and the P6230, 1.5 GHz, 450/50 Ω ×10, variable-offset probe for ECL circuits.

The 067-1155-99 calibration fixture is specific to the 7A42.


Bandwidth 350 MHz
  • 0.1 / 0.2 / 0.5 V/Div (TTL mode)
  • 20 / 50 / 100 mV/Div (ECL mode)
  • each direct or through 10:1 probe
Input impedance 1 MΩ or 50 Ω
Max. input voltage
  • at 1 MΩ: 25 V (DC+peak AC) below 36 MHz, down to 3 VAC at 300 MHz
  • at 50 Ω: 5 VRMS during any 1 ms interval
Trigger level
  • −1.27 to +1.28 V (TTL mode) in 10 mV steps
  • −254 mV to +256 mV (ECL mode) in 2 mV steps (or ×10)
Hysteresis 40 mV (TTL), 8 mV (ECL) (or ×10)
  • NiCd battery to preserve front-panel control status
Weight 2.8 kg / 6.2 lb


The 7A42's functions are controlled by an Intel 8085A microprocessor.

Each of the four input attenuator circuits contains five miniature relays. The bistable relay coils are wired in a 4x5 matrix.

The 7A42 contains its own switch mode PSU, based on an SG3524 controller, that generates +5 V, −2 V and −5 V from the mainframe's ±50 V rails.

See Also