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3A74: Difference between revisions
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The Tektronix | {{Plugin Sidebar | ||
560-series scopes. | |manufacturer=Tektronix | ||
switchable input attenuators and then into a cathode-follower made from a 7586 | |series=560-series scopes | ||
Nuvistor triode | |type=3A74 | ||
|summary=2 MHz four channel vertical amp plug-in | |||
|image=Tek 3a74 front.jpeg | |||
|caption=3A74 front | |||
|introduced=1962 | |||
|discontinued=1974 | |||
|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 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]]. | |||
{{BeginSpecs}} | |||
{{Spec | Bandwidth | 2 MHz}} | |||
{{Spec | Input impedance | 1 MΩ // 47 pF }} | |||
{{Spec | Deflection | 20 mV/Div to 10 V/Div in 1–2–5 sequence }} | |||
{{Spec | Features | | |||
* Invert switch per channel | |||
}} | |||
{{EndSpecs}} | |||
==Links== | |||
{{Documents|Link=3A74}} | |||
==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 | 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, | ||
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are generated by a transistor-based ring oscillator, a four-state cyclic state machine. | 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. | 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 [[:Category:Repair_issues|maintenance issue]]. | |||
The 3A74 contains a total of eight 7586 [[Nuvistor]]s. | |||
==Links== | |||
* [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] | |||
* [https://www.radiomuseum.org/r/tektronix_3a74_plug_in_unit.html Tek 3A74 @ radiomuseum.org] | |||
==Pictures== | |||
'''US-Made Version''' | |||
<gallery> | |||
Tek_3A74_front.jpg | |||
Tek 3a74 1.JPG|Front Side | |||
Tek 3a74 2.JPG|Rear Side | |||
Tek 3a74 3.JPG|Left Side | |||
Tek 3a74 4.JPG|Right Side | |||
3a74 block diagram.png|Block Diagram | |||
3a74 switching.png|Channel Switching | |||
3a74 amp schem.png|Amplifier | |||
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 | |||
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> | |||
==Components== | |||
{{Parts|3A74}} | |||
[[Category:560 series plugins]] | |||