3A74: Difference between revisions

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==Pictures==
==Pictures==
<gallery>
<gallery>
File:Tek 3a74 1.JPG|Front Side
Tek 3a74 1.JPG|Front Side
File:Tek 3a74 2.JPG|Rear Side
Tek 3a74 2.JPG|Rear Side
File:Tek 3a74 3.JPG|Left Side
Tek 3a74 3.JPG|Left Side
File:Tek 3a74 4.JPG|Right Side
Tek 3a74 4.JPG|Right Side
File:3a74 block diagram.png|Block Diagram
3a74 block diagram.png|Block Diagram
File:3a74 switching.png|Channel Switching
3a74 switching.png|Channel Switching
File:3a74 amp schem.png|Amplifier
3a74 amp schem.png|Amplifier
File:Tek 311-0304-00 pot.jpg|VAR GAIN potentiometer, sometimes problematic
Tek 311-0304-00 pot.jpg|VAR GAIN potentiometer, sometimes problematic
Tek 3a74 s1.jpg
Tek 3a74 s2.jpg
Tek 3a74 s3.jpg
Tek 3a74 s4.jpg
Tek 3a74 s5.jpg
</gallery>
</gallery>




[[Category:560 series plugins]]
[[Category:560 series plugins]]

Revision as of 08:28, 22 November 2017

Template:Plugin Sidebar 2 The Tektronix Type 3A74 is a four-channel vertical plug-in introduced in 1963 for 560-series scopes. The bandwidth is DC to 2 MHz.

A modified 3A74 (with a charge pre-amplifier on channel 1 to accommodate piezoelectric pressure transducers) was part of the Engine Analyzer package.

Key Specifications

Bandwidth 2 MHz
Input impedance 1 MΩ // 47 pF
Deflection 20 mV/Div to 10 V/Div in 1–2–5 sequence
Features
  • Invert switch per channel

Internals

Each input signal passes through switchable input attenuators and then into a cathode-follower made from a 7586 Nuvistor triode. That drives a PNP differential amplifier. The output of this differential amplifier, for each of the four channels, passes through a diode-based analog signal switching network (multiplexer). The output of that multiplexer drives the output amplifier, which is part transistor, part tube. The one-hot select line signals for the multiplexer are generated by a transistor-based ring oscillator, a four-state cyclic state machine. This allows each of the input signals to be traced on the screen, one after another.

The 3A74 uses Tek-made 185-ohm potentiometers in for the VAR GAIN controls. These can be a maintenance issue.

Links

Pictures