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{{Plugin Sidebar 2 |
{{Plugin Sidebar  
title=Tektronix 7L12 |
|manufacturer=Tektronix
summary=1.8 GHz Spectrum Analyzer |
|series=7000-series scopes
image=Tek-7l12-led-front.jpg |
|type=7L12  
caption=Tektronix 7L12 (later model) |
|summary=1.8 GHz Spectrum Analyzer
introduced=1971 |
|image=Tek-7l12-led-front.jpg
discontinued=1988 |
|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 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.
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.


Early models had a mechanical reference level readout. Later, front panel outputs
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.
for 1st and 2nd LO were added to allow connecting a [[TR501]] or [[TR502]] tracking generator.
The manual advises to use the variable control to reduce sweep speed until the signal amplitudes don't change.
Late models had LED reference level readout.


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.
The Tek catalogs suggested the [[7603]] Opt.06 or [[7613]] Opt.06 as suitable mainframes.


The Tek catalogs suggested the [[7603]] Opt.06 or [[7613]] Opt.06 as suitable mainframes.
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]]''.


{{BeginSpecs}}
{{BeginSpecs}}
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{{Spec|Sweep                | 1 μs/Div to 5 ms/Div (1-2-5)}}
{{Spec|Sweep                | 1 μs/Div to 5 ms/Div (1-2-5)}}
{{Spec|Resolution bandwidth | 300 Hz – 3 MHz in decade steps}}
{{Spec|Resolution bandwidth | 300 Hz – 3 MHz in decade steps}}
{{Spec|Sensitivity          | -115 dBm at 300 Hz}}
{{Spec|Sensitivity          | −115 dBm at 300 Hz}}
{{Spec|Vertical scale      | 10 dB/Div, 2 dB/Div or linear}}
{{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|Reference level      | −100 dB<sub>m</sub> – +30 dB<sub>m</sub> }}
{{Spec|Video filters        | 30 kHz, 300 Hz or 3 Hz}}
{{Spec|Video filters        | 30 kHz, 300 Hz or 3 Hz}}
{{Spec|Features            |
{{Spec|Features            |
Line 41: Line 47:
==Internals==
==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. This 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.   
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.
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.
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==
==Prices==
Line 53: Line 73:
! Year
! Year
! 1971  
! 1971  
! 1974
! 1976
! 1980   
! 1980   
! 1984  
! 1984  
Line 59: Line 81:
! Catalog price
! Catalog price
| align="right" | $4,850  
| align="right" | $4,850  
| align="right" | $4,850
| align="right" | $4,995
| align="right" | $6,500  
| align="right" | $6,500  
| align="right" | $10,250  
| align="right" | $10,250  
| align="right" | $12,500  
| align="right" | $12,500  
|-
|-
! 2015 value
! 2020 Dollars
| align="right" | $28,100
| align="right" | $31,000
| align="right" | $18,760
| align="right" | $25,500
| align="right" | $23,460
| align="right" | $22,700
| align="right" | $24,800
| align="right" | $20,400
| align="right" | $25,500
| align="right" | $27,350
|-
|-
|}
|}
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]


==Links==
==Links==
Line 75: Line 105:
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_special/spectrumanalyzer_7L12.htm Tek 7L12 @ 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]
* [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]


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






[[Category:7000 series combined plugins]]
[[Category:7000 series combined plugins]]
[[Category:Spectrum Analyzers]]
[[Category:Spectrum analyzers]]

Revision as of 13:24, 14 October 2022

Manuals – Specifications – Links – Pictures

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.

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.

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.

The Tek catalogs suggested the 7603 Opt.06 or 7613 Opt.06 as suitable mainframes.

According to 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.

Key Specifications

Input frequency 100 kHz – 1.8 GHz (Opt.39: 2.5 GHz)
Span 500 Hz/Div – 100 MHz/Div
Sweep 1 μs/Div to 5 ms/Div (1-2-5)
Resolution bandwidth 300 Hz – 3 MHz in decade steps
Sensitivity −115 dBm at 300 Hz
Vertical scale 10 dB/Div, 2 dB/Div or linear
Reference level −100 dBm – +30 dBm
Video filters 30 kHz, 300 Hz or 3 Hz
Features
  • Automatic phase lock
  • Built-in calibrator
  • Base line clipper

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 1st mixer. The 1st LO is a YIG oscillator running at 2.095 GHz to 3.9 GHz, resulting in a 2.095 GHz 1st IF.

The 1st 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 2nd mixer. The 2nd LO oscillates at 2.2 GHz (variable by ±1 MHz) for a 2nd IF of 105 MHz, which is amplified, then filtered in a 3-stage helical filter with 3 MHz bandwidth before passing through a 3rd 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 1st 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 2nd LO is swept instead of the 1st. 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

Year 1971 1974 1976 1980 1984 1988
Catalog price $4,850 $4,850 $4,995 $6,500 $10,250 $12,500
2020 Dollars $31,000 $25,500 $22,700 $20,400 $25,500 $27,350

According to an internal memo, in 1979 annual sales were estimated at 365 units.

Mods

Links

Pictures

Custom ICs used in the 7L12

Page Model Part nos Description Designers Used in
155-0028-00 M018 155-0028-00 155-0028-01 155-0042-00 155-0042-01 155-0042-02 155-0042-03 Miller integrator and delay pickoff Joe Burger 5030 R5030 5031 R5031 1401 1401A 1480 1481 1482 1485 26G1 26G2 26G3 314 335 432 434 4701 5B10N 5B12N 5B31 5B40 5B42 5S14N 7B52 7B53A 7B53N 7L12 7L13 7L14 7L18 7S14 AN/USM-281C RG501 Telequipment D63 Telequipment DM63
155-0035-00 M053B 155-0035-00 155-0116-00 quad op-amp Mike Metcalf 3110 3S7 3T7 492 492A 492AP 492P 494 494P 496 496P 4010 4011 4012 4013 7L5 7L12 7L13 7L14 7L18 7S11 7T11 7S12 S-6 1461 4602 P7001 613 653
155-0056-00 M042E 155-0056-00 155-0056-01 sweep control Val Garuts 26G1 26G2 26G3 314 4701 5B10N 5B12N 5S14N 7L5 7L12 7L13 7L14 7L18 7S14 5S14N RG501 Telequipment D63 Telequipment DM63