7J20
The Tektronix 7J20, which only appears in the 1975 catalog, is a "rapid scan" optical spectrometer for the 250 nm to 1100 nm region. Rapid scan means that it can capture the spectrum quickly enough to show spectral changes at temporal resolution of a few milliseconds.
The spectrometer is packaged in two enclosures linked by an umbilical cable. The 7J20 is a 2-wide plug-in for 7000-series scopes containing the sweep timing and mainframe interface circuits. The external enclosure is labeled "J20". It has controls for the optical components (grating, filters etc.) on one side and an input aperture on the other.
The 7J20 is very rare. According to Dennis Tillman, Best estimate is ~40 were actually built.
Key Specifications
| Spectral range | 250 nm to 1100 nm |
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| Resolution |
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| Slit | 10 to 5000 μm wide (1-2-5 sequence), 10 mm high |
| Filters | ND1, ND 2, 500 nm monopass, 800 nm monopass, UV block (≤400 nm), UV pass (250-330 nm), open (no filter) |
| Scan | 10 or 20 ms base sweep, 50 to 1000 ms (1–2–5) settings run successive 20 ms sweeps up to the selected integration time |
| Display span | Grating A, 40, 20, 10 or 4 nm/Div ; Grating B, 4, 2, 1 or 0.4 nm/Div |
Price
$12,000 in 1975 (~$68,000 in 2023 dollars)
Links
- Rapid Scan Optical Spectrometer @ VintageTek.org
- 7J20 in operation @ VintageTek Museum (YouTube)
- G.M.Ehemann Jr., Rapid scan determination of optical spectra. In RCA Engineer 25-2, August/September 1979. Discusses application of the 7J20 with a P7001 DPO and a PFP-11 computer to measure TV phosphor emission spectra.
Documents Referencing 7J20
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Patents that may apply to 7J20
| 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 3886331A | Electronic scanning spectrophotometer system | Joseph Philip Schierer Jr | 1973-09-14 | 1975-05-27 | 7J20 |
Internals
The instrument is based on a Czerny-Turner Monochromator, in essence a narrow slit followed by a diffraction grating. A vidicon tube scans the optical spectrum and produces a periodic electric signal which is then displayed by the scope mainframe.
The internal vidicon horizontal scan voltage corresponds to wavelength, but not in a linear way. To provide a linear nm/div horizontal display on the 7000-series mainframe, the vidicon horizontal scan signal is passed through a function generator IC, the 155-0106-00 (U1550 and U1590), which implements an interpolated lookup table. Inside the J20, there are 40 trimmer potentiometers that allow the lookup function to be tweaked so that the horizontal scale of the system is accurate.
Pictures
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7J20 (plug-in part) in 7633 mainframe
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7J20 plug-in part and J20 spectrometer connected (catalog picture)
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7J20 with J20 in measurement setup (1975 catalog picture)
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7J20 with J20 in 7704A/P7001(1975 catalog picture)
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J20 UV Fiber Optic Sensor
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J20 UV Fiber Optic Sensor Head
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J20 UV Fiber Optic Sensor Slit
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J20 Mounting Ring Adapter Face
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J20 Mounting Ring Adapter Back
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J20 Mounting Ring Adapter Side
Components
Some Parts Used in the 7J20
| Part | Part Number(s) | Class | Description | Used in |
|---|---|---|---|---|
| 151-0261-00 | 151-0261-00 | Discrete component | dual PNP transistor | AM501 • AM502 • CG5001 • CG551AP • FG501 • FG502 • FG503 • OF150 • OF151 • OF152 • OF235 • OS261 • RM502A • R1140 • R5030 • R5031 • R7912 • 067-0679-00 • 067-0807-00 • 1101 • 1140A • 1141 • 1142 • 1350 • 145 • 1450 • 1480 • 1481 • 1482 • 1485 • 1501 • 1801 • 1900 • 1910 • 1980 • 213 • 26A1 • 26A2 • 2620 • 285 • 3A9 • 3A10 • 3S1 • 3S2 • 3S5 • 3S6 • 432 • 434 • 4501 • 454 • 4601 • 4602 • 4610 • 4612 • 4620 • 4632 • 4634 • 4701 • 475 • 492 • 492A • 492AP • 494 • 494P • 496 • 496P • 5A13N • 5A20N • 5A21N • 5A22N • 5A26 • 5L4N • 502A • 5030 • 5031 • 576 • 690SR • 7A22 • 7A29 • 7B51 • 7B71 • 7J20 • 7L5 • 7S11 • 7S12 • 7912AD |
| 155-0014-01 | 155-0014-00 • 155-0014-01 | Monolithic integrated circuit | analog-to-decimal converter | 7000 series readout system • 7854 • 7934 • 7J20 • 7L5 • P7001 |
| 155-0090-00 | 155-0090-00 • 155-0090-01 • 155-0090-02 | Monolithic integrated circuit | four-decade counter, latch and D/A converter | 7B85 • 7D01 • 7D12 • 7D15 • 7J20 |
| 155-0104-00 | 155-0104-00 | Monolithic integrated circuit | custom legend generator | 7J20 |
| 155-0105-00 | 155-0105-00 | Monolithic integrated circuit | custom legend generator | 7J20 |
| 155-0171-00 | 155-0171-00 | Monolithic integrated circuit | four-decade counter, latch and D/A converter | 7B85 • 7D01 • 7D12 • 7D15 • 7J20 |
Some Parts Used in the J20
| Part | Part Number(s) | Class | Description | Used in |
|---|---|---|---|---|
| 155-0106-00 | 155-0106-00 | Monolithic integrated circuit | normalizer | J20 • 492 • 492A • 492AP • 492P • 494 • 494P |