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{{Plugin Sidebar|
{{Plugin Sidebar  
title=Tektronix 7L12|
|manufacturer=Tektronix
summary=1.8 GHz Spectrum Analyzer|
|series=7000-series scopes
image=tek-7l12.jpg|
|type=7L12  
caption=|
|summary=1.8 GHz Spectrum Analyzer
years=?|
|image=Tek-7l12-led-front.jpg
type=combined horizontal/vertical plugin|
|caption=Tektronix 7L12 (later model)
series=[[7000-series scopes]]|
|introduced=1971
manuals=
|discontinued=1988
* [http://w140.com/mmm/tek-7l12.pdf Tektronix 7L12 Manual (PDF)]
|designers=Morris Engelson;Linley Gumm;Gene Kauffman;Larry Lockwood;Gordon Long;Steve Morton;Paul Parks;Fred Telewski;Neal Broadbent;Jack Doyle;Al Huegli;Steve Skidmore;Leighton Whitsett;Judy Hanson; Robert Holmes;Carolyn Moore;Rena Randle
* [http://w140.com/smb/7l12_sm.pdf Tektronix 7L12 Manual (OCR, PDF)]
|manuals=
* [http://w140.com/7l12_foldouts_sm.pdf Tektronix 7L12 Schematics (PDF)]
* [[Media:070-1298-01.pdf|Tektronix 7L12 Instruction Manual -01]] / ''[[Media:070-1298-01.pdf|Alternate copy]] (OCR)''
* [[Media:070-1298-02.pdf|Tektronix 7L12 Instruction Manual -02]]
* [https://w140.com/7l12_foldouts_sm.pdf Tektronix 7L12 Schematics]
* [[Media:Tek 7L12 factory cal december 1972.pdf|Tektronix 7L12 Factory Calibration Procedure]]
* [[Media:26W-4889.pdf|No Loose Ends - Brochure for using the spectrum analyzer for CATV]]
* [[Media:26AX-3582-3.pdf|FM Broadcast Measurements Using the Spectrum Analyzer]]
}}
}}
The '''Tektronix 7L12''' is a 1.8 GHz Spectrum Analyzer plug-in for [[7000-series scopes]].
It is a double-width plugin to be installed in the right vertical and left (or only) horizontal bay.


The Tektronix 7L12 is an 1.8 GHz Spectrum Analyzer plug-in for [[7000-series scopes]].
Early models had a mechanical reference level readout. Later, front panel outputs for 1st and 2nd LO were added to allow connecting a [[TR501]] or [[TR502]] tracking generator. Late models had LED reference level readout.


==Specifications==
The 7L12 does not have the UNCAL indicator typical for spectrum analyzers that alerts the operator when the sweep speed is too fast for the given resolution.
The manual advises to use the variable control to reduce sweep speed until the signal amplitudes don't change.


* Input frequency 100 kHz – 1.8 GHz
The Tek catalogs suggested the [[7603]] Opt.06 or [[7613]] Opt.06 as suitable mainframes.
* Span 500 Hz/Div – 100 MHz/Div
 
* Sweep 1 μs/Div to 5 ms/Div (1-2-5)
According to [[Media:Tekscope_1972_V4_N1_Jan_1972.pdf|Tekscope Vol.4 No.1 Jan 1972]], the design teams included: ''Electrical Engineering – [[Morris Engelson]], [[Linley Gumm]], [[Gene Kauffman]], [[Larry Lockwood]], [[Gordon Long]], [[Steve Morton]], [[Paul Parks]], [[Fred Telewski]]. Mechanical Engineering – [[Neal Broadbent]], [[Jack Doyle]], [[Al Huegli]], [[Steve Skidmore]], [[Leighton Whitsett]]. Integrated Circuits – [[Judy Hanson]], [[Robert Holmes]], [[Carolyn Moore]], [[Rena Randle]]''.
* Resolution bandwidth 300 Hz – 3 MHz
 
* Sensitivity -115 dBm at 300 Hz.
{{BeginSpecs}}
* Vertical: 10 dB/Div, 2 dB/Div or linear
{{Spec|Input frequency     | 100 kHz – 1.8 GHz (Opt.39: 2.5 GHz) }}
* Reference level: -100 dB<sub>m</sub> – +30 dB<sub>m</sub>
{{Spec|Span                 | 500 Hz/Div – 100 MHz/Div}}
* Video filters: 30 kHz, 300 Hz or 3 Hz
{{Spec|Sweep               | 1 μs/Div to 5 ms/Div (1-2-5)}}
{{Spec|Resolution bandwidth | 300 Hz – 3 MHz in decade steps}}
{{Spec|Sensitivity         | −115 dBm at 300 Hz}}
{{Spec|Vertical scale      | 10 dB/Div, 2 dB/Div or linear}}
{{Spec|Reference level     | −100 dB<sub>m</sub> – +30 dB<sub>m</sub> }}
{{Spec|Video filters       | 30 kHz, 300 Hz or 3 Hz}}
{{Spec|Features            |
* Automatic phase lock  
* Automatic phase lock  
* Built-in calibrator
* Built-in calibrator
* Base line clipper
* Base line clipper
}}
{{EndSpecs}}


==Links==
==Links==
* http://www.barrytech.com/tektronix/tek7000/tek7l12.html
* [[Media:Tekscope 1972 V4 N1 Jan 1972.pdf  | Tekscope Vol. 4 No. 1, Jan 1972]]
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_special/spectrumanalyzer_7L12.htm Tek 7L12 page at amplifier.cd]
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_special/spectrumanalyzer_7L12.htm Tek 7L12 @ amplifier.cd]
* [http://www.barrytech.com/tektronix/tek7000/tek7l12.html Tek 7L12 @ barrytech.com]
* [https://www.youtube.com/watch?v=f02rCpkjs8Q 7L12 repair] by vintageTek Museum @ YouTube (shows how to pull out the center board)
* 7L12 videos: [https://youtube.com/watch?v=eEsL9443Rt8 #1] / [https://youtube.com/watch?v=a5-IXJEqMbM #2] / [https://youtube.com/watch?v=ctL8NuEvQhk #3] / [https://youtube.com/watch?v=oZA2Fa78_00 #4] [https://youtu.be/f02rCpkjs8Q #5]
{{Documents|Link=7L12}}
 
==Internals==
 
The 7L12 is a traditional triple-mixing spectrum analyzer design.
The input signal runs through a step attenuator (0 to 60 dB in 10 dB steps),
a 1.8 GHz low-pass filter and a 3 dB pad (to isolate the mixer from LPF reflections) to a 1<sup>st</sup> mixer.
The 1<sup>st</sup> LO is a YIG oscillator running at 2.095 GHz to 3.9 GHz, resulting in a 2.095 GHz 1<sup>st</sup> IF.
 
The 1<sup>st</sup> IF passes through a "traveling wave damper" (isolator),
a 2.2 GHz LPF and a 10 MHz wide 2.095 GHz bandpass filter before reaching the 2<sup>nd</sup> mixer.
The 2<sup>nd</sup> LO oscillates at 2.2 GHz (variable by ±1 MHz) for a 2<sup>nd</sup> IF of 105 MHz, which is amplified,
then filtered in a 3-stage helical filter with 3 MHz bandwidth before passing through a 3<sup>rd</sup> mixer to the final 10 MHz IF,
variable resolution filters, and post-resolution amplifier to the "Function IF amplifier" that implements the linear or logarithmic detector.
 
A phase lock circuit controls the 1<sup>st</sup> LO at spans of 0.1 MHz/Div and less,
tying its frequency to a multiple of 2.21 MHz using a diode sampler employed as a mixer.
The sampling gate is driven by an avalanche pulser.  In phase lock, the 2<sup>nd</sup> LO is swept instead of the 1<sup>st</sup>.
The fine frequency control is only operational in phase lock mode, one of the key limitations of this design.
 
The 7L12 includes a standard sweep circuit built around the [[155-0056-00]] Sweep Control (U1140)
and [[155-0042-02]] (U1160) Miller Integrator custom ICs.
The 7L12 also uses the TEK-custom quad opamp [[155-0035-00]] in several places.
 
==Prices==
 
{| class="wikitable"
|-
! Year
! 1971
! 1974
! 1976
! 1980 
! 1984
! 1988
|-
! Catalog price
| align="right" | $4,850
| align="right" | $4,850
| align="right" | $4,995
| align="right" | $6,500
| align="right" | $10,250
| align="right" | $12,500
|-
! In 2023 Dollars
| align="right" | $36,400
| align="right" | $29,900
| align="right" | $26,700
| align="right" | $24,000
| align="right" | $30,000
| align="right" | $32,100
|-
|}
According to an [[Media:Tek Schottky Diodes Memo rot.pdf|internal memo]], in 1979 annual sales were estimated at 365 units.
 
==Mods==
* [https://w140.com/Tek7L12-139U.pdf Tektronix 7L12 Mod 139U Increases Bandwidth to 2.5 GHz]


==Pictures==
==Pictures==
<gallery>
<gallery>
File:Two 7L12s.jpg
Tek-7l12-led-front.jpg    | 7L12, later version with LED reference level display, front
Tek-7l12-left.jpg          | Left side
Tek-7l12-top.jpg          | Top view
Tek-7l12-right.jpg        | Right side
Tek-712-right-front.jpg        | Right side toward front.  The 1<sup>st</sup> mixer (bottom left) and 1<sup>st</sup> LO (large cylindrical can) are visible.
Tek-7l12-bottom.jpg        | Bottom view
Tek-7l12-bottom-front.jpg  | Bottom front
Tek-7l12-bottom-center.jpg | Bottom center. The 3-stage 2<sup>nd</sup> IF 105 MHz helical filter is visible in the middle (black cylinders).
Tek-7l12-top-front.jpg    | Top front
Tek-7l12-center-1.jpg      | Tektronix 7L12, center board extended
Tek-7l12-center-2.jpg      | Tektronix 7L12, center board extended, back side. 2nd IF (105 MHz) helical filter seen near bottom.
7l12-105m-helix.jpg        | 7L12 105 MHz Helix filter.  From Tekscope, Jan 1972
Two 7L12s.jpg              | later and early model side by side
tek-7l12.jpg              | early model
Tek 7l12 trace.jpg
</gallery>
</gallery>
==Components==
{{Parts|7L12}}






[[Category:7000 series combined plugins]]
[[Category:7000 series combined plugins]]
[[Category:Spectrum Analyzers]]
[[Category:7000 series spectrum analyzer plugins]]
 
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