7D20
The Tektronix 7D20 is a two-channel digitizing plug-in for 7000-series scopes. It is a triple-width plug-in and provides both vertical and horizontal signals to the scope. The 7D20 can digitally store waveforms and has a GPIB interface.
A special version of the rackmount large screen R7603 exists (Opt. 20), which provides a rear-panel GPIB connector to be used with the 7D20.
The 7D20T consists of the 7D20 and its own dedicated power module, for use in applications not requiring local visual display of acquired signals.
Key Specifications
| Bandwidth | 70 MHz |
|---|---|
| Rise time | < 5 ns |
| Sampling Rate | 40 MS/s |
| Resolution | 8 bit |
| Deflection | 5 mV/div to 5 V/div, 1–2–5 |
| Input impedance | 1 MΩ // 20 pF |
| Time base |
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| External clock | < 10 kHz |
| Memory | 2 × 455 cells (alternating) analog / 1024 words digital |
| Features |
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| Weight | 3.9 kg (8.5 lb) |
Links
- 7D20 page @ amplifier.cd
- EB5AGV's Tektronix R7603 / 7D20 page - 7D20+R7603 Repair Report
- Another 7D20 repair
- 7D20 @ barrytech.com (waybackarchive)
Documents referencing 7D20
| Document | Class | Title | Authors | Year | Links |
|---|---|---|---|---|---|
| 42W-5311.pdf | Application Note | Human pattern recognition speeds automated testing | Clark Foley | 1983 | 7D20 |
| 7D20 SMPS AnalysisDFT Apr1984.pdf | Article | Use a personal computer and DFT to extract data from noisy signals | Clark Foley • Jim Lamb | 1984 | 7854 • 7A42 • 7D20 |
Patents that may apply to 7D20
| Page | Title | Inventors | Filing date | Grant date | Links |
|---|---|---|---|---|---|
| Patent US 3584174A | Push-button switch apparatus having cam actuated switch contacts and selective illumination means | Tony Sprando • Peter S Winkelmann | 1969-06-09 | 1971-06-08 | Back-lit switches • 326 • 7A11 • 7A12 • 7A13 • 7A14 • 7A16 • 7A16P • 7A22 • 7A42 • 7B42N • 7B50 • 7B51 • 7B52 • 7B53A • 7B70 • 7B71 • 7B92 • 7B92A • 7D10 • 7D11 • 7D12 • 7D14 • 7D15 • 7D20 • 7L5 • 7L12 • 7L13 • 7L14 • 7L18 • 7M13 • 7S11 • 7S12 • 7T11 • 067-0587-00 • 067-0587-01 • 067-0587-02 • 067-0587-10 |
Prices
| Year | Catalog price | In 2026 dollars |
|---|---|---|
| 1983 | $7,750 | ~$25,900 |
| 1984 | $7,750 | ~$24,800 |
| 1986 | $7,265 | ~$22,100 |
| 1988 | $7,590 | ~$21,400 |
| 1989 | $7,590 | ~$20,400 |
| 1990 | $8,400 | ~$21,400 |
| 1991 | $10,750 | ~$26,300 |
Internals
The 7D20 uses an analog shift register (CCD) for high-speed signal acquisition, and then digitizes the stored analog signal at a lower speed (see Patent US 4527117A). This design allowed the 7D20 to capture single-shot events at 40 MSamples/s even though this exceeded the speed of ADCs of the time. A microprocessor (68B09) in the plug-in controls most of its functions.
The analog waveforms that are sent to the 7000-series mainframe are generated by vertical and horizontal DACs. The DACs outputs can be calibrated for scaling and shift so that signals are accurately displayed on the oscilloscope screen.
The 7D20 has a "roll" mode that emulates a paper roll chart, as if the waveform were being drawn by a pen on the right side of the screen while the paper is being moved to the left at a constant rate. No equivalent to "roll" exists in analog scopes. The Tektronix 2212/2216, 2220/2221/2230 and possibly others also have this feature.
The 7D20 can give NVRAM errors that are often easy to fix.
Pictures
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7D20 picture from manual
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7D20 picture in 7603 mainframe, from manual
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Bottom view showing interesting latch design
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Top view
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EDN Magazine Cover, 10 Nov 1982
