420: Difference between revisions

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{{Instrument Sidebar
{{Instrument Sidebar
|manufacturer=Tektronix
|manufacturer=Tektronix
|class=power supply
|model=420
|model=420
|class=power supply
|summary=high-voltage power supply
|summary=high-voltage power supply
|image=420A_1.JPG
|image=420A_1.JPG
|caption=420 internal view
|caption=420 internal view
|series=96000-series scopes
|introduced=1950
|introduced=
|discontinued=(?)
|discontinued=(?)
|manuals=
|manuals=
* ''Manual needed, please add'' [[Category:Manual needed]]
* ''Manual needed, please add'' [[Category:Manual needed]]
}}
}}
The '''Tektronix 420''' is a high-voltage power supply used in the [[507|Type 507]] and [[517|Type 517]] scope. It contains the transformers, rectifier tubes and filter capacitors in a separate enclosure with ceramic output feed-through posts.
The '''Tektronix 420''' is a high-voltage power supply used in the [[507|Type 507]] and [[517|Type 517]] scope.
It contains transformers, rectifier tubes and filter capacitors in a separate, oil-filled enclosure with ceramic output feed-through posts.


{{MissingSpecs}}
{{BeginSpecs}}
Output voltages are +20 kV and –4 kV.  Later models add +13.3 kV and +6.6 kV output taps.
{{Spec | Outputs | +20 kV @ 200 μA / –4 kV @ 700 μA, or +10 kV @ 400 μA / –4 kV @ 1.4 mA.  Later models add +13.3 kV and +6.6 kV output taps (6.6 kV/3.3 kV in reduced output mode). }}
{{EndSpecs}}


==Internals==
==Internals==
The 420 contains two transformers, one for the high voltage, and a second for the HV rectifier heaters.
The HV rectifiers are five [[1X2]] tubes, one for the negative and four in a Cockroft-Walton quadrupler circuit for the positive outputs.
The HV rectifiers are five [[1X2]] tubes, one for the negative and four in a Cockroft-Walton multiplier for the positive outputs.
To accommodate the switchable output voltage, rectifier heaters are supplied from a second transformer inside the 420.


The transformers are driven by independent oscillators using tubes located on the mainframe chassis, a [[6AU5]] for HV and a [[6AQ5]] for heaters.
The transformers are driven by independent oscillators using tubes located on the mainframe chassis, a [[6AU5]] for HV and a [[6AQ5]] for heaters.
In the 517, the HV oscillator runs off an unregulated supply through its own DC series regulator with no feedback path from the HV side, only the oscillator input voltage is regulated.
In the 517, the HV oscillator runs off an unregulated supply through its own DC series regulator with no feedback path from the HV side, only the oscillator input voltage is regulated.
The 507 HV oscillator, supplied from the regulated +225 V rail, takes feedback from the negative HV output..
The 507 HV oscillator, supplied from the regulated +225 V rail, takes feedback from the negative HV output..
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==Pictures==
==Pictures==
<gallery>
<gallery>
Tek 420 hvps.png|Entry in 1950 Catalog
Tek 420 hvps.png       | Entry in 1950 Catalog
Tek_517_hvps2.png|Schematic of 420 in the Type 517
Tek 517 420 hv.jpg     | later model 420 (with 13 and 6 kV outputs) in a [[517]]
Tek 517 420 hv.jpg | later model 420 (with 13 and 6 kV outputs) in a [[517]]
Tek_517_hvps2.png      | Schematic of 420 (to the right of and including the transformers) in the Type 517
420A_1.JPG| opening power supply  type 420A, five [[1X2]] high voltage rectifier tubes
Tek_507_crt_circuit.png | Schematic of 420 (between the dashed lines) in the Type 517
420A_2.JPG| opening power supply  type 420A, many capacitors
420A_1.JPG             | Five [[1X2]] high voltage rectifier tubes inside a 420A
420A_2.JPG             | HV multiplier, "[[black beauty]]" capacitors inside a 420A
</gallery>
</gallery>


Revision as of 00:35, 24 August 2023

Tektronix 420
high-voltage power supply
420 internal view

Produced from 1950 to (?)

Manuals
  • Manual needed, please add
(All manuals in PDF format unless noted otherwise)
Manuals – Specifications – Links – Pictures

The Tektronix 420 is a high-voltage power supply used in the Type 507 and Type 517 scope. It contains transformers, rectifier tubes and filter capacitors in a separate, oil-filled enclosure with ceramic output feed-through posts.

Key Specifications

Outputs +20 kV @ 200 μA / –4 kV @ 700 μA, or +10 kV @ 400 μA / –4 kV @ 1.4 mA. Later models add +13.3 kV and +6.6 kV output taps (6.6 kV/3.3 kV in reduced output mode).

Internals

The HV rectifiers are five 1X2 tubes, one for the negative and four in a Cockroft-Walton quadrupler circuit for the positive outputs. To accommodate the switchable output voltage, rectifier heaters are supplied from a second transformer inside the 420.

The transformers are driven by independent oscillators using tubes located on the mainframe chassis, a 6AU5 for HV and a 6AQ5 for heaters.

In the 517, the HV oscillator runs off an unregulated supply through its own DC series regulator with no feedback path from the HV side, only the oscillator input voltage is regulated. The 507 HV oscillator, supplied from the regulated +225 V rail, takes feedback from the negative HV output..

Pictures

  • Entry in 1950 Catalog

    Entry in 1950 Catalog

  • later model 420 (with 13 and 6 kV outputs) in a 517

    later model 420 (with 13 and 6 kV outputs) in a 517

  • Schematic of 420 (to the right of and including the transformers) in the Type 517

    Schematic of 420 (to the right of and including the transformers) in the Type 517

  • Schematic of 420 (between the dashed lines) in the Type 517

    Schematic of 420 (between the dashed lines) in the Type 517

  • Five 1X2 high voltage rectifier tubes inside a 420A

    Five 1X2 high voltage rectifier tubes inside a 420A

  • HV multiplier, "black beauty" capacitors inside a 420A

    HV multiplier, "black beauty" capacitors inside a 420A


Some Parts Used in the 420

Part Part Number(s) Class Description Used in
1X2 154-0005-00 Vacuum Tube (Diode) high-voltage rectifier 420 • 507 • 565
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