3A74: Difference between revisions

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{{Plugin Sidebar 2|
{{Plugin Sidebar  
title=Tektronix 3A74|
|manufacturer=Tektronix
summary=2 MHz four channel vertical amp|
|series=560-series scopes
image=tek-3a74-front.jpg |  
|type=3A74
caption=3A74 front|
|summary=2 MHz four channel vertical amp plug-in
introduced=1962 |
|image=Tek 3a74 front.jpeg
discontinued=1974 |
|caption=3A74 front
series=[[560-series scopes]]|
|introduced=1962  
manuals=
|discontinued=1974  
* [http://bama.edebris.com/download/tek/3a74/3a74.djvu Tektronix 3A74 Manual (DjVu)]
|manuals=
* [[Media:070-347.pdf|Tektronix 3A74 Manual]] (OCR)
* [[Media:Tek 3a74 fcp july 1969.pdf|Tektronix 3A74 Factory Calibration Procedure, July 1969‎]]
* [[Media:Tek 3a74 cal outline.pdf|Tektronix 3A74 Calibration Outline]] (OCR)
}}
}}
The '''Tektronix Type 3A74''' is a four-channel vertical plug-in [[introduced in 1963]] for
The '''Tektronix 3A74''' is a four-channel vertical plug-in [[introduced in 1963]] for [[560-series scopes]].  Bandwidth is DC to 2 MHz.   
[[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.
A modified 3A74/MOD730A (with a charge pre-amplifier on channel 1 to accommodate piezoelectric pressure transducers) was part of the [[Engine Analyzer System]].


{{BeginSpecs}}
{{BeginSpecs}}
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}}
}}
{{EndSpecs}}
{{EndSpecs}}
==Links==
{{Documents|Link=3A74}}


==Internals==
==Internals==
Each input signal passes through switchable input attenuators and then into a cathode-follower  
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
made from a [[7586]] Nuvistor triode driving a PNP differential amplifier.  The output of this
differential amplifier, for each of the four channels, passes through a diode-based
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,
analog signal switching network (multiplexer).  The output of that multiplexer drives the output amplifier,
Line 33: Line 38:
This allows each of the input signals to be traced on the screen, one after another.
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.
The 3A74 uses Tek-made 185 Ω [[potentiometers]] in for the VAR GAIN controls.
These can be a [[:Category:Repair_issues|maintenance issue]].
These can be a [[:Category:Repair_issues|maintenance issue]].
The 3A74 contains a total of eight 7586 [[Nuvistor]]s.
==Links==
==Links==
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_other/3A74.htm Tek 3A74 @ amplifier.cd]
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_other/3A74.htm Tek 3A74 @ amplifier.cd]
* [http://www.barrytech.com/tektronix/vintage/tek3a74.html Tek 3A74@ barrytech.com]
* [http://www.barrytech.com/tektronix/vintage/tek3a74.html Tek 3A74 @ barrytech.com]
* [https://www.radiomuseum.org/r/tektronix_3a74_plug_in_unit.html Tek 3A74 @ radiomuseum.org]


==Pictures==
==Pictures==
'''US-Made Version'''
<gallery>
<gallery>
Tek_3A74_front.jpg
Tek 3a74 1.JPG|Front Side
Tek 3a74 1.JPG|Front Side
Tek 3a74 2.JPG|Rear Side
Tek 3a74 2.JPG|Rear Side
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Tek 3a74 s4.jpg
Tek 3a74 s4.jpg
Tek 3a74 s5.jpg
Tek 3a74 s5.jpg
Tek 3a74 front.jpg
Tek 3a74 right.jpg
Tek 3a74 left.jpg
Tek 3a74 top.jpg
Tek 3a74 bottom.jpg
Tek 3a74 rear.jpg
Tek 3a74 engine analyzer amplifier.jpg|3A74 Engine Analyzer Amplifier (note CH1 calibrated in PSI/div)
</gallery>
'''Netherlands-Made Version'''
<gallery>
Tek 3a74 nl1.jpg
Tek 3a74 nl2.jpg
Tek 3a74 nl3.jpg
</gallery>
</gallery>
==Components==
{{Parts|3A74}}




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

Latest revision as of 08:37, 8 December 2023

Tektronix 3A74
2 MHz four channel vertical amp plug-in
3A74 front

Compatible with 560-series scopes

Produced from 1962 to 1974

Manuals
Manuals – Specifications – Links – Pictures

The Tektronix 3A74 is a four-channel vertical plug-in introduced in 1963 for 560-series scopes. Bandwidth is DC to 2 MHz.

A modified 3A74/MOD730A (with a charge pre-amplifier on channel 1 to accommodate piezoelectric pressure transducers) was part of the Engine Analyzer System.

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

Links

Documents Referencing 3A74

Document Class Title Authors Year Links
070-0890-00.pdf Manual Engine Analyzer System 1968 Engine Analyzer System • 561B • 564B • 3A74 • 2B67 • 015-0108-00
Tekscope 1969 V1 N2 Apr 1969.pdf Article A New Insight Into Reciprocating Machinery Bill Verhoef 1969 Engine Analyzer System • 3A74 • 561B • 564B

Internals

Each input signal passes through switchable input attenuators and then into a cathode-follower made from a 7586 Nuvistor triode driving 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 Ω potentiometers in for the VAR GAIN controls. These can be a maintenance issue.

The 3A74 contains a total of eight 7586 Nuvistors.

Links

Pictures

US-Made Version

  • Front Side

    Front Side

  • Rear Side

    Rear Side

  • Left Side

    Left Side

  • Right Side

    Right Side

  • Block Diagram

    Block Diagram

  • Channel Switching

    Channel Switching

  • Amplifier

    Amplifier

  • VAR GAIN potentiometer, sometimes problematic

    VAR GAIN potentiometer, sometimes problematic

  • 3A74 Engine Analyzer Amplifier (note CH1 calibrated in PSI/div)

    3A74 Engine Analyzer Amplifier (note CH1 calibrated in PSI/div)

Netherlands-Made Version

Components

Some Parts Used in the 3A74

Part Part Number(s) Class Description Used in
6CL6 154-031 • 154-0031-00 • 154-0286-00 Vacuum Tube (Pentode) 7.5 W power pentode 132 • 310 • 310A • 316 • 317 • 515 • 524 • 525 • 531 • 535 • 535A • 545 • 545A • 545B • 549 • 570 • 581 • 581A • 585 • 585A • 3A74
7586 154-0306-00 Vacuum Tube (Triode) Nuvistor triode M • 1A1 • 1A2 • 1A5 • 10A2 • 10A2A • 11B1 • 11B2A • 321 • 321A • 3A1 • 3A1S • 3A3 • 3A5 • 3A6 • 3A7 • 3A8 • 3A74 • 3S76 • 3T77 • 3T77A • 3B5 • 4S1 • 4S2 • 6R1 • 6R1A • 9A1 • 9A2 • 82 • 86 • S-311
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