7J20: Difference between revisions

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series=[[7000-series scopes]]|
series=[[7000-series scopes]]|
manuals=
manuals=
* [[Media:70-1642-00.pdf|Tektronix J20/7J20 Service Manual (PDF)]]
* [[Media:70-1641-00.pdf|Tektronix J20/7J20 Operators Manual (PDF)]]
* [[Media:Tek 7j20 interim service manual.pdf|Tektronix J20/7J20 Interim Service Manual (PDF)]]
* [[Media:070-1743-00.pdf|Tektronix 016-1000-00 RSS External Normalizer Manual (PDF)]]
* [[Media:TEK RSS Brochure.pdf|Tektronix J20/7J20 Brochure (PDF)]]
* [[Media:RSS Applications.pdf|Tektronix J20/7J20 Application Notes 9 & 11 (PDF)]]
* [[Media:RSS R&D Article 11-1974.pdf|R/D Article - November 1974 (PDF)]]
* [http://w140.com/tek_7J20_from_1975_cat.pdf Section in 1975 Catalog in 7J20 (PDF)]
* [http://w140.com/tek_7J20_from_1975_cat.pdf Section in 1975 Catalog in 7J20 (PDF)]
* [[Media:Jere marrs rapid-scanning spectrometry no ocr.pdf|Jere Marrs, "Rapid-Scanning Spectrometry" (PDF)]]
* [[Media:TEK 7J20 Advertisement 06-1975.pdf|Tektronix J20/7J20 Advertisement - June 1975 (PDF)]]
* [[Media:Peter burke fast-scan spectrometry no ocr.pdf|Peter Burke "Fast-Scan Spectrometry" (PDF)]]
* [[Media:Jere marrs rapid-scanning spectrometry.pdf|Jere Marrs, "Rapid-Scanning Spectrometry" (PDF)]]
* Manual needed [[Category:Manual needed]]
* [[Media:Peter burke fast-scan spectrometry.pdf|Peter Burke "Fast-Scan Spectrometry" (PDF)]]
}}
}}


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==Internals==
==Internals==
The instrument is based on a [https://en.wikipedia.org/wiki/Monochromator Czerny-Turner Monochromator],  
The instrument is based on a [[wikipedia:Monochromator|Czerny-Turner Monochromator]],  
in essence a narrow slit followed by a [https://en.wikipedia.org/wiki/Diffraction_grating diffraction grating].
in essence a narrow slit followed by a [[wikipedia:Diffraction grating|diffraction grating]].
A [https://en.wikipedia.org/wiki/Vidicon vidicon tube] scans the optical spectrum
A [[wikipedia:Vidicon|vidicon tube]] scans the optical spectrum
and produces a periodic electric signal which is then displayed by the scope mainframe.  
and produces a periodic electric signal which is then displayed by the scope mainframe.  
[[File:7J20-principle.jpg | thumb | 400px | center | Operating principle (click to enlarge) ]]
[[File:7J20-principle.jpg | thumb | 400px | center | Operating principle (click to enlarge) ]]
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the [[155-0106-00]] (U1550 and U1590),
the [[155-0106-00]] (U1550 and U1590),
which implements an interpolated lookup table.
which implements an interpolated lookup table.
Inside the 7J20, there are 40 trimmer potentiometers that allow the lookup function to be tweaked
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.
so that the horizontal scale of the system is accurate.
[[File:Tek_j20_interim_normalizer2.png | thumb | 400px | center | Normalizer (click to enlarge) ]]
[[File:Tek_j20_interim_normalizer2.png | thumb | 400px | center | Normalizer (click to enlarge) ]]
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==Links==
==Links==
* [https://youtube.com/watch?v=7zR4Os6JEac 7J0 in operation @ VintageTek Museum] (YouTube)
* [https://youtube.com/watch?v=7zR4Os6JEac 7J20 in operation @ VintageTek Museum] (YouTube)


==Pictures==
==Pictures==
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7J20_complete.jpg      | 7J20 plug-in part and J20 spectrometer connected (catalog picture)
7J20_complete.jpg      | 7J20 plug-in part and J20 spectrometer connected (catalog picture)
7J20_from_1975_cat.jpg | 7J20 with J20 in measurement setup (catalog picture)
7J20_from_1975_cat.jpg | 7J20 with J20 in measurement setup (catalog picture)
 
Tek j20 internal 1.jpg|J20
Tek j20 internal 2.jpg|J20
Tek j20 internal 3.jpg|J20
Tek j20 internal 4.jpg|J20
Tek j20 internal 5.jpg|J20
Tek j20 internal 6.jpg|J20
Tek j20 front 1.jpg|J20
Tek 7j20 1.jpg|7J20
Tek 7j20 2.jpg|7J20
Tek 7j20 3.jpg|7J20
Tek 7j20 4.jpg|7J20
Tek 7j20 5.jpg|7J20
Tek 7j20 6.jpg|7J20
Tektronix-J20 UV Fiber Optic Sensor-Full-lores.JPG | J20 UV Fiber Optic Sensor
Tektronix-J20 UV Fiber Optic Sensor-Head-lores.JPG | J20 UV Fiber Optic Sensor Head
Tektronix-J20 UV Fiber Optic Sensor-Slit-lores.JPG | J20 UV Fiber Optic Sensor Slit
Tektronix-J20 Ring Adapter-Face-hires.JPG  | J20 Mounting Ring Adapter Face
Tektronix-J20 UV Fiber Optic Sensor-Ring Adpapter-Back-hires.JPG |J20 Mounting Ring Adapter Back
Tektronix-J20 UV Fiber Optic Sensor-Ring Adpater-Side-hires.JPG |J20 Mounting Ring Adapter Side
</gallery>
</gallery>


[[Category:7000 series combined plugins]]
[[Category:7000 series combined plugins]]
[[Category:7000 series special-function plugins]]
[[Category:7000 series special-function plugins]]
[[Category:Spectrum Analyzers]]
[[Category:Spectrum analyzers]]
[[Category:Optoelectronic instruments]]
[[Category:Optoelectronic instruments]]


[[Category:Specifications needed]]
[[Category:Specifications needed]]

Revision as of 12:45, 24 March 2020

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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.

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.

Operating principle (click to enlarge)

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.

Normalizer (click to enlarge)

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
Resolution (Grating A) ≤4 nm in a 400 nm span (selectable 300-700, 400-800, 500-900, 600-1000, or 700-1100 nm
Resolution (Grating B) ≤0.4 nm in a 40 nm span continuously variable through the spectral range
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 ($57,000 equivalent in 2018)

Links

Pictures