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{{Plugin Sidebar|
{{Plugin Sidebar
title=Tektronix 7A18|
|manufacturer=Tektronix
summary=75 MHz dual channel amplifier|
|type=7A18
image=Tek 7a18 front.jpg |  
|summary=75 MHz dual-channel amplifier
caption=7A18 front view|
|image=Tek-7a18a-front.jpg
years=? |
|caption=7A18 front view
type=Vertical Amplifier|
|introduced=1971
series=[[7000-series scopes]]|
|discontinued=1992
manuals=
|series=7000-series scopes
* [http://bama.edebris.com/download/tek/7a18/Tektronix_7A18_Service_June1974.pdf Tektronix 7A18 Manual (PDF)]
|designers=Tom Rousseau
* [http://bama.edebris.com/download/tek/7a18a/tek-7a18a.pdf Tektronix 7A18A Manual (PDF)]
|manuals=
* [http://w140.com/smb/7a18_7a18n_sm.pdf Tektronix 7A18+7A18N Manual (OCR, PDF)]
* [[Media:070-1126-01.pdf|Tektronix 7A18+7A18N Instruction Manual]] (OCR)
* [http://w140.com/smb/7a18a_sm.pdf Tektronix 7A18A Manual (OCR, PDF)]
* [[Media:070-4329-00.pdf|Tektronix 7A18A Instruction Manual]] (OCR)
<small>
'''Alternates'''
* [http://bama.edebris.com/download/tek/7a18/Tektronix_7A18_Service_June1974.pdf Tektronix 7A18 Manual] @ BAMA
* [http://bama.edebris.com/download/tek/7a18a/tek-7a18a.pdf Tektronix 7A18A Manual] @ BAMA
</small>
}}
}}
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]].


The Tektronix 7A18 is a general-purpose 75 MHz dual-trace vertical plug-in for [[7000-series scopes]].
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.


Model 7A18N is identical except it omits the readout circuits.
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.


==Specifications== 
The 7A18(A) uses a discrete front-end followed by [[M036|M36]] channel switch ICs for the vertical and trigger signals.
Input impedance: 1 M&Omega; in parallel with 20 pF. 
 
Deflection factors: 5 mV/div to 5 V/div
The 200 MHz [[7A26]] and 400 MHz [[7A24]] share the same front panel layout and operation.
 
{{BeginSpecs}}
{{Spec | Input impedance | 1 MΩ  // 20 pF }}
{{Spec | Deflection | 5 mV/div to 5 V/div in 1–2–5 sequence, 2% }}
{{Spec | Bandwidth | 0 – 75 MHz (DC),  10 Hz – 75 MHz (AC) }}
{{Spec | Noise | < 300 μV in 5 mV/Div }}
{{Spec | Option 06 offset range | ±200 Div equiv. from ±1 V in 5 mV/Div range up to ±200 V in 1 V/Div range (above that limited by maximum input voltage) }}
{{Spec | Features |
* Mode: CH1 only, CH2 only, Add CH1+CH2, Alternating, Chopped.  CH2 can be inverted.
* Input sockets with contact ring for probe &times;10 / identify information
* No bandwidth limiter switch
}}
{{Spec | Weight | 1.4 kg }}
{{EndSpecs}}
 
==Links==
* [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
{{Documents|Link=7A18}}
{{PatentLinks|7A18}}
 
==Prices==
{| class="wikitable"
|-
! Year
! 1971
! 1976
! 1980
! 1984
! 1990
|-
! Catalog Price
|align=right|  $535
|align=right|  $615
|align=right|  $915
|align=right| $1,250
|align=right| $1,790
|-
! In 2023 Dollars
|align=right| $4,100
|align=right| $3,300
|align=right| $3,400
|align=right| $3,700
|align=right| $4,200
|-
|}


==Pictures==
==Pictures==
<gallery>
<gallery>
Image:7a18a-left.jpg | 7A18A left side
Tek_7a18.jpg                                        | 7A18 Front
Image:7a18a-right.jpg | 7A18A right side
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>
</gallery>
===7A18A===
<gallery>
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-right.jpg                    | 7A18A right side.  The circuit boards on top carry the readout circuitry.
</gallery>
'''Option 06'''
<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-left.jpg  | 7A18A Opt.06 left side (rear).  Note the two blue 10T-potentiometers for offset voltage adjustment.
Tek-7a18a-opt06-offset.jpg | 7A18A Opt.06 - offset controls take the place of the Identify buttons on the standard model.
</gallery>
==Components==
{{Parts|7A18}}
{{Parts|7A18A}}




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

Latest revision as of 10:55, 4 October 2024

Tektronix 7A18
75 MHz dual-channel amplifier
7A18 front view

Compatible with 7000-series scopes

Produced from 1971 to 1992

Manuals

Alternates

(All manuals in PDF format unless noted otherwise)
Manuals – Specifications – Links – Pictures

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 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.

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 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.

Key Specifications

Input impedance 1 MΩ // 20 pF
Deflection 5 mV/div to 5 V/div in 1–2–5 sequence, 2%
Bandwidth 0 – 75 MHz (DC), 10 Hz – 75 MHz (AC)
Noise < 300 μV in 5 mV/Div
Option 06 offset range ±200 Div equiv. from ±1 V in 5 mV/Div range up to ±200 V in 1 V/Div range (above that limited by maximum input voltage)
Features
  • Mode: CH1 only, CH2 only, Add CH1+CH2, Alternating, Chopped. CH2 can be inverted.
  • Input sockets with contact ring for probe ×10 / identify information
  • No bandwidth limiter switch
Weight 1.4 kg

Links

Documents Referencing 7A18

Document Class Title Authors Year Links
7000 series brochure March 1973.pdf Brochure 7000 series brochure, March 1973 1973 7A11 • 7A12 • 7A13 • 7A14 • 7A15A • 7A16A • 7A17 • 7A18 • 7A19 • 7A21N • 7A22 • 7B50 • 7B53A • 7B70 • 7B71 • 7B92 • 7CT1N • 7D11 • 7D13 • 7D14 • 7D15 • 7M11 • 7L12 • 7S11 • 7S12 • 7T11 • 7704A • R7704 • 7904 • R7903 • 7603 • R7603 • 7403N • R7403N • 7313 • R7313 • 7613 • R7613 • 7623 • R7623 • P7001
Tekscope 1977 V9 N1.pdf Article Counter and Oscilloscope Combination Makes Difficult Measurements Emory Harry 1977 DC505A • 7B53A • 7A18 • 7603

Patents that may apply to 7A18

Page Title Inventors Filing date Grant date Links
Patent US 3562464A Cam actuated switch having movable and fixed contacts on circuit board Howard Vollum • Willem H Verhoef • Tony Sprando 1968-10-07 1971-02-09 Cam switches • 2101 • 2701 • 2703 • 432 • 434 • 465 • 475 • 5A15N • 5A18N • 5A20N • 5A21N • 5A38 • 5A45 • 5B10N • 5B12N • 7A15 • 7A16A • 7A18 • 7A19 • 7A24 • 7A26 • 7B10 • 7B15 • 7B50 • 7B51 • 7B52 • 7B53A • 7B50A • 7B70 • 7B71 • 7B80 • 7B85 • 7B87 • 7B92 • 7B92A • 7D01 • 7D12 • 7D15 • 7J20 • 7S12 • 7T11 • 7T11A • AF501 • AM502 • AM503 • DC502 • DC503 • DC504 • DC505 • DM501 • DM502 • FG501 • FG501A • FG502 • FG503 • FG504 • FG507 • PG501 • PG502 • PG505 • PG506 • PG506A • PG508 • TG501 • SC502 • SC503 • SC504
Patent US 3719788A Switch having ganged contacts mounted on opposite sides of circuit board Ken Holland • Tony Sprando 1971-02-04 1973-03-06 465 • 475 • 5A38 • 5A45 • 7A15 • 7A16A • 7A18 • 7A19 • 7A24 • 7A26 • 7D15 • PG506
Patent US 3753170A Step attenuator apparatus having attenuator stages selectively connected in cascade by cam actuated switches Ken Holland 1971-02-10 1973-08-14 465 • 475 • 5A38 • 5A45 • 7A15 • 7A16A • 7A18 • 7A19 • 7A24 • 7A26
Patent US 3900711A Electrical contactor assembly for high frequency applications Ken Holland 1974-02-04 1975-08-19 465 • 475 • 5A38 • 5A45 • 7A15 • 7A16A • 7A18 • 7A19 • 7A24 • 7A26 • 7D15 • AM503

Prices

Year 1971 1976 1980 1984 1990
Catalog Price $535 $615 $915 $1,250 $1,790
In 2023 Dollars $4,100 $3,300 $3,400 $3,700 $4,200

Pictures

  • 7A18 Front

    7A18 Front

  • 7A18 attenuator opened. One of the attenuation R/C modules has been unplugged to reveal the switch contacts.

    7A18 attenuator opened. One of the attenuation R/C modules has been unplugged to reveal the switch contacts.

  • 7A18 attenuator, bottom (switch) side

    7A18 attenuator, bottom (switch) side

  • A 7603 with two 7A18s

    A 7603 with two 7A18s

  • 7A18 in 7613 mainframe

    7A18 in 7613 mainframe

  • 7A18 and 7A18N from service manual 070-1126-01

    7A18 and 7A18N from service manual 070-1126-01

  • 7A18N with "Identify" seen on an auction site - probably cobbled parts

    7A18N with "Identify" seen on an auction site - probably cobbled parts

  • 7A18N Front

    7A18N Front

  • 7A18N RHS switch cover removed

    7A18N RHS switch cover removed

  • 7A18N LHS switch cover removed

    7A18N LHS switch cover removed

  • Broken bond between ganged gain pots

    Broken bond between ganged gain pots

  • Broken bond between ganged gain pots zoomed

    Broken bond between ganged gain pots zoomed

  • Intact epoxy between ganged gain pots

    Intact epoxy between ganged gain pots

Development Prototypes

  • First prototype of 7A18

    First prototype of 7A18

  • First prototype of 7A18

    First prototype of 7A18

  • Second prototype of 7A18

    Second prototype of 7A18

  • Second prototype of 7A18

    Second prototype of 7A18

  • Third prototype of 7A18

    Third prototype of 7A18

  • Third prototype of 7A18

    Third prototype of 7A18

  • Third prototype of 7A18

    Third prototype of 7A18

7A18A

  • 7A18A Front

    7A18A Front

  • 7A18A left side. The step attenuators can be seen on the left, the amplifier board on the right.

    7A18A left side. The step attenuators can be seen on the left, the amplifier board on the right.

  • 7A18A right side. The circuit boards on top carry the readout circuitry.

    7A18A right side. The circuit boards on top carry the readout circuitry.

Option 06

  • 7A18A Opt.06 Front. AC/GND/DC switches have an extra rightmost "DC Offset" position enabling the offset controls.

    7A18A Opt.06 Front. AC/GND/DC switches have an extra rightmost "DC Offset" position enabling the offset controls.

  • 7A18A Opt.06 left side (rear). Note the two blue 10T-potentiometers for offset voltage adjustment.

    7A18A Opt.06 left side (rear). Note the two blue 10T-potentiometers for offset voltage adjustment.

  • 7A18A Opt.06 - offset controls take the place of the Identify buttons on the standard model.

    7A18A Opt.06 - offset controls take the place of the Identify buttons on the standard model.

Components

Some Parts Used in the 7A18

Part Part Number(s) Class Description Used in
155-0022-00 155-0022-00 • 155-0022-01 Monolithic integrated circuit analog multiplexer 147 • 148 • 149 • 335 • 468 • 1430 • 1441 • 1461 • 1900 • 1910 • 2220 • 2221 • 2230 • 5223 • 5403 • 5440 • 5441 • 5443 • 5444 • 5A38 • 7313 • 7403N • 7503 • 7504 • 7514 • 7603 • AN/USM-281C • 7613 • 7623 • 7623A • 7633 • 7704 • R7704 • 7704A • 7834 • 7844 • 7854 • R7912 • 7912AD • 7912HB • 7904 • R7903 • 7904A • 7934 • 7A12 • 7A18 • 7A18A • 7A18N • 7B52 • 7B53N • 7D10 • 7D11 • 7D12 • NT-7000 • P7001


Some Parts Used in the 7A18A

Part Part Number(s) Class Description Used in
155-0022-00 155-0022-00 • 155-0022-01 Monolithic integrated circuit analog multiplexer 147 • 148 • 149 • 335 • 468 • 1430 • 1441 • 1461 • 1900 • 1910 • 2220 • 2221 • 2230 • 5223 • 5403 • 5440 • 5441 • 5443 • 5444 • 5A38 • 7313 • 7403N • 7503 • 7504 • 7514 • 7603 • AN/USM-281C • 7613 • 7623 • 7623A • 7633 • 7704 • R7704 • 7704A • 7834 • 7844 • 7854 • R7912 • 7912AD • 7912HB • 7904 • R7903 • 7904A • 7934 • 7A12 • 7A18 • 7A18A • 7A18N • 7B52 • 7B53N • 7D10 • 7D11 • 7D12 • NT-7000 • P7001
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