7A18: Difference between revisions

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designers=Tom Rousseau|
designers=Tom Rousseau|
manuals=
manuals=
* [[Media:070-1126-01.pdf|Tektronix 7A18+7A18N Instruction Manual]] (OCR, PDF)
* [[Media:070-1126-01.pdf|Tektronix 7A18+7A18N Instruction Manual]] (OCR)
* [[Media:070-4329-00.pdf|Tektronix 7A18A Instruction Manual]] (OCR, PDF)
* [[Media:070-4329-00.pdf|Tektronix 7A18A Instruction Manual]] (OCR)
* [http://bama.edebris.com/download/tek/7a18/Tektronix_7A18_Service_June1974.pdf Tektronix 7A18 Manual (PDF)]
<small>
* [http://bama.edebris.com/download/tek/7a18a/tek-7a18a.pdf Tektronix 7A18A Manual (PDF)]
'''Alternates'''
* [http://w140.com/smb/7a18_7a18n_sm.pdf Tektronix 7A18+7A18N Manual (OCR, PDF)]
* [http://bama.edebris.com/download/tek/7a18/Tektronix_7A18_Service_June1974.pdf Tektronix 7A18 Manual] @ BAMA
* [http://w140.com/smb/7a18a_sm.pdf Tektronix 7A18A Manual (OCR, PDF)]
* [http://bama.edebris.com/download/tek/7a18a/tek-7a18a.pdf Tektronix 7A18A Manual] @ BAMA
</small>
}}
}}
The '''Tektronix 7A18''' is a general-purpose 75&nbsp;MHz dual-trace vertical plug-in for [[7000-series scopes]].  Model 7A18N is identical except it omits the [[7000 series readout system|readout circuits]].
The '''Tektronix 7A18''' is a general-purpose 75 MHz dual-trace vertical plug-in for [[7000-series scopes]].   
Model 7A18N is identical except it omits the [[7000 series readout system|readout circuits]].


Option 06 (first offered in 1975 catalog) adds offset voltage controls giving ±200 Div offset range.  This option replaces the IDENTIFY buttons with DC offset controls and adds a fourth "DC offset" position to the input coupling switch.
Option 06 (first offered in 1975 catalog) adds offset voltage controls giving ±200 Div offset range.   
This option replaces the IDENTIFY buttons with DC offset controls, and adds a fourth "DC offset" position to the input coupling switch.
 
The '''7A18A''' is mostly identical to the 7A18 predecessor, but replaces the custom low inductance potentiometers for gain and variable gain setting with a FET attenuator and regular potentiometers.
 
The 7A18(A) uses a discrete front-end followed by [[M036|M36]] channel switch ICs for the vertical and trigger signals.


The 200 MHz [[7A26]] and 400 MHz [[7A24]] share the same front panel layout and operation.
The 200 MHz [[7A26]] and 400 MHz [[7A24]] share the same front panel layout and operation.
The 7A18 uses a discrete front-end followed by [[M036|M36]] channel switch ICs for the vertical and trigger signals.


{{BeginSpecs}}
{{BeginSpecs}}
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* [https://www.youtube.com/watch?v=JZ76egcWH_4 Tektronix 7A18 II Repair and Alignment (With a Deeper Look at the High Frequency Compensation)] @ Zenwizard Studios YouTube
* [https://www.youtube.com/watch?v=JZ76egcWH_4 Tektronix 7A18 II Repair and Alignment (With a Deeper Look at the High Frequency Compensation)] @ Zenwizard Studios YouTube
* [https://youtu.be/Cz9kxXKlWUw Tektronix 7A18 Repair and Function Generator Alignment] @ Zenwizard Studios YouTube
* [https://youtu.be/Cz9kxXKlWUw Tektronix 7A18 Repair and Function Generator Alignment] @ Zenwizard Studios YouTube
{{Documents|Link=7A18}}
{{PatentLinks|7A18}}


==Prices==
==Prices==
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! 1990
! 1990
|-
|-
! Catalog price
! Catalog Price
|align=right|  $535
|align=right|  $535
|align=right|  $615
|align=right|  $615
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|align=right| $1,790
|align=right| $1,790
|-
|-
! 2018 value
! In 2023 Dollars
|align=right| $3,300
|align=right| $4,100
|align=right| $2,700
|align=right| $3,300
|align=right| $2,770
|align=right| $3,400
|align=right| $3,000
|align=right| $3,700
|align=right| $3,420
|align=right| $4,200
|-
|-
|}
|}


==Repair issues==
==Pictures==
The pins of the attenuator modules are connected to conductive traces on the ceramic substrate inside by low-temperature soldering, which can go bad.
<gallery>
Re-seating the module can temporarily restore the internal contact but will usually not fix the problem permanently.
Tek_7a18.jpg                                        | 7A18 Front
Repair is possible by opening the click-locked lid and carefully resoldering.
7a18-attenuator.jpg                                | 7A18 attenuator opened.  One of the attenuation R/C modules has been unplugged to reveal the switch contacts.
Tek 7A18 attenuator bottom.jpg                      | 7A18 attenuator, bottom (switch) side
Tek-7603-front.jpg                                  | A [[7603]] with two 7A18s
Tek 7a17 7a18 7b50a model3 cart.jpg                | 7A18 in [[7613]] mainframe
7A18 and 7A18N from 070-1126-01.png                | 7A18 and 7A18N from service manual 070-1126-01
Tek 7a18n.jpeg                                      | 7A18N with "Identify" seen on an auction site - probably cobbled parts
7A18N front.jpg                                    | 7A18N Front
7A18N RHS.jpg                                      | 7A18N RHS switch cover removed
7A18N LHS.jpg                                      | 7A18N LHS switch cover removed
7A18 R237A and B broken bond.jpg                    | Broken bond between ganged gain pots
7A18N split ganged gain epoxy bond split zoom.png  | Broken bond between ganged gain pots zoomed
7A18 intact epoxy bond between ganged gain pots.jpg | Intact epoxy between ganged gain pots
</gallery>
===Development Prototypes===
<gallery>
Tek 7a18 first prototype 1.jpg  | First prototype of 7A18
Tek 7a18 first prototype 2.jpg  | First prototype of 7A18
Tek 7a18 second prototype 1.jpg | Second prototype of 7A18
Tek 7a18 second prototype 2.jpg | Second prototype of 7A18
Third prototype of 7a18 1.jpg  | Third prototype of 7A18
Third prototype of 7a18 2.jpg  | Third prototype of 7A18
Third prototype of 7a18 3.jpg  | Third prototype of 7A18
</gallery>


==Pictures==
===7A18A===
<gallery>
<gallery>
Tek_7a18.jpg                        | 7A18 Front
Tek-7a18a-front.jpg                | 7A18A Front
Tek-7a18a-front.jpg                | 7A18A Front
7a18a-left.jpg                      | 7A18A left side.  The step attenuators can be seen on the left, the amplifier board on the right.
7a18a-left.jpg                      | 7A18A left side.  The step attenuators can be seen on the left, the amplifier board on the right.
7a18a-right.jpg                    | 7A18A right side.  The circuit boards on top carry the readout circuitry.
7a18a-right.jpg                    | 7A18A right side.  The circuit boards on top carry the readout circuitry.
7a18-attenuator.jpg                | 7A18 attenuator opened.  One of the attenuation R/C modules has been unplugged to reveal the switch contacts.
Tek 7A18 attenuator bottom.jpg      | 7A18 attenuator, bottom (switch) side
Tek-7603-front.jpg                  | A [[7603]] with two 7A18s
Tek 7a17 7a18 7b50a model3 cart.jpg | 7A18 in [[7613]] mainframe
</gallery>
</gallery>


===Option 06===
'''Option 06'''
 
<gallery>
<gallery>
Tek-7a18a-opt06-front.jpg  | 7A18A Opt.06 Front. AC/GND/DC switches have an extra rightmost "DC Offset" position enabling the offset controls.
Tek-7a18a-opt06-front.jpg  | 7A18A Opt.06 Front. AC/GND/DC switches have an extra rightmost "DC Offset" position enabling the offset controls.
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</gallery>
</gallery>


==Components==
{{Parts|7A18}}


==7A18N==
{{Parts|7A18A}}
<gallery>
Tek 7a18n.jpeg
</gallery>
 
{{Custom ICs|7A18}}




[[Category:7000 series vertical plugins]]
[[Category:7000 series vertical plugins]]