7A18
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 |
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| Weight | 1.4 kg |
Links
- Tektronix 7A18 II Repair and Alignment (With a Deeper Look at the High Frequency Compensation) @ Zenwizard Studios YouTube
- Tektronix 7A18 Repair and Function Generator Alignment @ Zenwizard Studios YouTube
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
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7A18 Front
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7A18 attenuator opened. One of the attenuation R/C modules has been unplugged to reveal the switch contacts.
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7A18 attenuator, bottom (switch) side
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A 7603 with two 7A18s
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7A18 in 7613 mainframe
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7A18 and 7A18N from service manual 070-1126-01
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7A18N with "Identify" seen on an auction site - probably cobbled parts
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7A18N Front
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7A18N RHS switch cover removed
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7A18N LHS switch cover removed
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Broken bond between ganged gain pots
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Broken bond between ganged gain pots zoomed
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Intact epoxy between ganged gain pots
Development Prototypes
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First prototype of 7A18
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First prototype of 7A18
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Second prototype of 7A18
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Second prototype of 7A18
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Third prototype of 7A18
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Third prototype of 7A18
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Third prototype of 7A18
7A18A
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7A18A Front
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7A18A left side. The step attenuators can be seen on the left, the amplifier board on the right.
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7A18A right side. The circuit boards on top carry the readout circuitry.
Option 06
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7A18A Opt.06 Front. AC/GND/DC switches have an extra rightmost "DC Offset" position enabling the offset controls.
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7A18A Opt.06 left side (rear). Note the two blue 10T-potentiometers for offset voltage adjustment.
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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 |