3A74: Difference between revisions

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{{Plugin Sidebar  
{{Plugin Sidebar  
|manufacturer=Tektronix
|manufacturer=Tektronix
|series=560-series scopes
|series=560-series scopes
|type=3A74
|type=3A74
|summary=2 MHz four channel vertical amp
|summary=2 MHz four channel vertical amp plug-in
|image=Tek_3A74_front_crop.jpg
|image=Tek 3a74 front.jpeg
|caption=3A74 front
|caption=3A74 front
|introduced=1962  
|introduced=1962  
|discontinued=1974  
|discontinued=1974  
|manuals=
|manuals=
* [http://bama.edebris.com/download/tek/3a74/3a74.djvu Tektronix 3A74 Manual (DjVu)]
* [[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 fcp july 1969.pdf|Tektronix 3A74 Factory Calibration Procedure, July 1969‎]]
* [[Media:Tek 3a74 cal outline.pdf|Tektronix 3A74 Calibration Outline (PDF, OCR)]]
* [[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 [[560-series scopes]].  The bandwidth is DC to 2 MHz.   
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 MOD 730A (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==
Line 47: Line 49:


==Pictures==
==Pictures==
===US-made Version===
'''US-Made Version'''
<gallery>
<gallery>
Tek_3A74_front.jpg
Tek_3A74_front.jpg
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Tek 3a74 bottom.jpg
Tek 3a74 bottom.jpg
Tek 3a74 rear.jpg
Tek 3a74 rear.jpg
Tek 3a74 engine analyzer amplifier.jpg|3A74 Engine Analyzer Amplifier
Tek 3a74 engine analyzer amplifier.jpg|3A74 Engine Analyzer Amplifier (note CH1 calibrated in PSI/div)
</gallery>
</gallery>
===Netherlands-made Version===
 
'''Netherlands-Made Version'''
<gallery>
<gallery>
Tek 3a74 nl1.jpg
Tek 3a74 nl1.jpg
Line 78: Line 81:
</gallery>
</gallery>


==Components==
{{Parts|3A74}}




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

Latest revision as of 09:37, 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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