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The Tektronix 7B85 is a 400 MHz delaying timebase for [[7000-series scopes]]. 
{{Plugin Sidebar
The trigger circuit is similar to that of the [[7B80]].
|manufacturer=Tektronix  
The digital delay differentiates the 7B85 from the 7B80.
|series=7000-series scopes
|type=7B85  
|summary=400 MHz delaying timebase
|image=Tek 7b85 front.jpg
|caption=Tektronix 7B85 Delaying Timebase plug-in
|introduced=1976
|discontinued=1990
|designers=Les Larson;Bruce Hofer;Paul Farley;Art Metz;
|manuals=
* [[Media:070-1960-00.pdf|7B85 Operator's Manual]] (OCR)
* [[Media:070-1961-00.pdf|7B85 Instruction Manual 070-1961-00]]
* [[Media:070-1961-01.pdf|7B85 Instruction Manual 070-1961-01]] (OCR)


The 7B85 uses a [[155-0185-00]] digital voltmeter IC (U686).
<small>
* [https://bama.edebris.com/download/tek/7b85/Tektronix-7B85%20Delaying%20Time%20Base.pdf 070-1961-01 Alternate copy @ BAMA]
</small>
}}
The '''Tektronix 7B85''' is a 400 MHz delaying timebase for [[7000-series scopes]] with digital delay and delta time read-out capability, typically used in the 7800 Series, e.g. [[7844]].  It does not support X-Y mode.
 
The delay function differentiates the 7B85 from the otherwise similar [[7B80]]. The [[7B87]] is also similar to the 7B85 but provides an acquisition clock for a digital storage mainframe instead of a delay.
 
The [[7B85]]/[[7B80]] combination was introduced in 1976 to replace the 200 MHz [[7B71]]/[[7B70]] that had no digital delay read-out.  For the [[7104]] 1 GHz-class scopes, the [[7B15]]/[[7B10]] provide the functionality of 7B85/7B80.
 
From Tekscope Vol.8 No.1, 1976:
<blockquote>
[[Les Larson]] developed the trigger circuitry and served as Project Manager for the 7B80 and 7B85.
The sweeps were designed by [[Bruce Hofer]] and the DVM and related logic by [[Paul Farley]]. Much credit is due [[Art Metz]] for his work on the trigger input IC which includes the peak-to-peak automatic trigger circuitry.
[[Gene Andrews]], Program Manager, provided overall direction for the project.
</blockquote>
 
{{BeginSpecs}}
{{Spec | Sweep | 10 ns/div to 5 s/div, 1−2−5; ×10 magnifier down to 1 ns/div; variable to ×2.5}}
{{Spec | Triggering | to 400 MHz }}
{{Spec | Features |
* Digital read-out of delay and delta times
* Variable Trigger Holdoff
* Peak-to-peak Auto Triggering
}}
{{EndSpecs}}
 
==Links==
* [https://m.youtube.com/watch?v=Hz-gF_XSj9w Demonstration of delay and delta time measurement on a 7B85]
{{Documents|Link=7B85}}
{{PatentLinks|7B85}}
 
==Internals==
The 7B85 uses a [[155-0185-00]] digital voltmeter IC (U686).  
A ramp generator is started when the trigger signal arrives.
A ramp generator is started when the trigger signal arrives.
The delayed sweep is started when a comparator detects that  
The delayed sweep is started when a comparator detects that the ramp has reached a control voltage, set by the front panel knobs on the 7B85.
the ramp has reached a control voltage,
set by the front panel knobs on the 7B85.
The control voltage is proportional to the amount of delay.
The control voltage is proportional to the amount of delay.
The digital voltmeter in the 7B85 digitizes the control voltage
and displays it on the oscilloscope readout, thereby providing
the operator with a precise readout of the delay.
Another way of setting up a precisely delay timebase is to use a time
mark generator such as the [[180A]], [[181]], [[184]], or [[2901]].


* [http://bama.edebris.com/download/tek/7b85/Tektronix-7B85%20Delaying%20Time%20Base.pdf Tektronix 7B85 Manual (PDF)]
The digital voltmeter in the 7B85 digitizes the control voltage and displays it on the [[7000 series readout system|oscilloscope readout]], thereby providing the operator with a precise readout of the delay.
* [http://w140.com/smb/7b85_sm.pdf Tektronix 7B85 Manual (OCR, PDF)]
 
Another way of setting up a precisely delayed timebase is to use a [[7D11]] digital delay module.
 
The 7B85 uses the +50 V supply provided by the mainframe.
 
==Prices==
{| class="wikitable"
|-
! Year
! 1977
! 1980
! 1984
! 1987
! 1990
|-
! Catalog price
|align=right| $895
|align=right| $1,200
|align=right| $1,700
|align=right| $1,940
|align=right| $2,400
|-
! In 2023 Dollars
|align=right| $4,500
|align=right| $4,500
|align=right| $5,000
|align=right| $5,200
|align=right| $5,600
|-
|}
 
==Pictures==
 
===Hardware===
<gallery>
Tek 7b85 front.jpg        | Front
7b85-left.jpg              | 7B85, left side
7b85-left-del-removed.jpg  | 7B85, left side, delay board removed
7b85-right.jpg            | 7B85, right side
Tek-7b15-vs-7b85-left.jpg  | Family resemblance: 7B15 (top) vs. 7B85 (bottom).  Left side.
Tek-7b15-vs-7b85-right.jpg | Family resemblance: 7B15 (top) vs. 7B85 (bottom).  Right side.
7b85 left rear.jpg        | Left rear
7b85 left front.jpg        | Left front
7b85 right front.jpg      | Right front
7b85 right rear.jpg        | Right rear
</gallery>
 
===Measurements===
These are examples of measurements with a [[7B85]] in the Horizontal A and a [[7B80]] in the Horizontal B compartment (of a [[7904]]).
 
Horizontal mode is set to alternating to show the pulse signal being triggered (A) and the delayed/magnified part (B).
<gallery>
7b85-risetime-5n.jpg  ‎| Measuring rise time of a pulse.  Delayed signal is scaled for 0-100% on graticule.  Delay time is adjusted so the trace crosses the 10% level on the center line.  Delta time is adjusted so the delta-delayed trace crosses 90% on the same vertical line.  Delta time readout indicates rise time directly.
7b85-risetime-10n.jpg | Measuring rise time of a pulse. Same as before, rise time increased to 10 ns (HP8112A generator).
7b85-pulse-width.jpg  ‎| Pulse width measurement.  Delayed signal and delta-delayed trace cross at 50%.  Delta time readout indicates pulse width directly.
7b85-period-1.jpg | Pulse period measurement.  Delta time is adjusted to overlay the delayed trace with one delayed by an additional period. In this picture, the two traces do not yet overlay exactly.
7b85-period-2.jpg | Pulse period measurement.  Delayed trace overlays with one delayed by an additional period, delta time reads pulse period.
</gallery>
 
==Components==
{{Parts|7B85}}
 


<gallery>
[[Category:7000 series horizontal plugins]]
File:7b85 left rear.jpg|Left rear
File:7b85 left front.jpg|Left front
File:7b85 right front.jpg|Right front
File:7b85 right rear.jpg|Right rear

Latest revision as of 09:14, 24 June 2024

Tektronix 7B85
400 MHz delaying timebase
Tektronix 7B85 Delaying Timebase plug-in

Compatible with 7000-series scopes

Produced from 1976 to 1990

Manuals
Manuals – Specifications – Links – Pictures

The Tektronix 7B85 is a 400 MHz delaying timebase for 7000-series scopes with digital delay and delta time read-out capability, typically used in the 7800 Series, e.g. 7844. It does not support X-Y mode.

The delay function differentiates the 7B85 from the otherwise similar 7B80. The 7B87 is also similar to the 7B85 but provides an acquisition clock for a digital storage mainframe instead of a delay.

The 7B85/7B80 combination was introduced in 1976 to replace the 200 MHz 7B71/7B70 that had no digital delay read-out. For the 7104 1 GHz-class scopes, the 7B15/7B10 provide the functionality of 7B85/7B80.

From Tekscope Vol.8 No.1, 1976:

Les Larson developed the trigger circuitry and served as Project Manager for the 7B80 and 7B85. The sweeps were designed by Bruce Hofer and the DVM and related logic by Paul Farley. Much credit is due Art Metz for his work on the trigger input IC which includes the peak-to-peak automatic trigger circuitry. Gene Andrews, Program Manager, provided overall direction for the project.

Key Specifications

Sweep 10 ns/div to 5 s/div, 1−2−5; ×10 magnifier down to 1 ns/div; variable to ×2.5
Triggering to 400 MHz
Features
  • Digital read-out of delay and delta times
  • Variable Trigger Holdoff
  • Peak-to-peak Auto Triggering

Links

Documents Referencing 7B85

Document Class Title Authors Year Links
Tekscope 1976 V8 N1.pdf Article Delta Time Measurement for the 7000 Series Paul Farley • Les Larson • Bruce Hofer 1976 7B85 • 7B80 • DM40 • DM43
Technology Report October 1979.pdf Article Patent Received: 4,109,182 Simultaneous Delayed Sweep Display Oliver Dalton 1979 Patent US 4109182A • 7B80 • 7B85 • 7B10 • 7B15

Patents that may apply to 7B85

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 4013855A Modular pushbutton switch John E. Reichen • Richard Neff Meyer • Gary W. Reed 1975-03-17 1977-03-22 CP501 • 7B10 • 7B15 • 7B50A • 7B80 • 7B85 • 7B87
Patent US 4109182A Delayed sweep system for an oscilloscope Oliver Dalton 1976-03-10 1978-08-22 7B80 • 7B85 • 7B10 • 7B15

Internals

The 7B85 uses a 155-0185-00 digital voltmeter IC (U686). A ramp generator is started when the trigger signal arrives. The delayed sweep is started when a comparator detects that the ramp has reached a control voltage, set by the front panel knobs on the 7B85. The control voltage is proportional to the amount of delay.

The digital voltmeter in the 7B85 digitizes the control voltage and displays it on the oscilloscope readout, thereby providing the operator with a precise readout of the delay.

Another way of setting up a precisely delayed timebase is to use a 7D11 digital delay module.

The 7B85 uses the +50 V supply provided by the mainframe.

Prices

Year 1977 1980 1984 1987 1990
Catalog price $895 $1,200 $1,700 $1,940 $2,400
In 2023 Dollars $4,500 $4,500 $5,000 $5,200 $5,600

Pictures

Hardware

  • Front

    Front

  • 7B85, left side

    7B85, left side

  • 7B85, left side, delay board removed

    7B85, left side, delay board removed

  • 7B85, right side

    7B85, right side

  • Family resemblance: 7B15 (top) vs. 7B85 (bottom). Left side.

    Family resemblance: 7B15 (top) vs. 7B85 (bottom). Left side.

  • Family resemblance: 7B15 (top) vs. 7B85 (bottom). Right side.

    Family resemblance: 7B15 (top) vs. 7B85 (bottom). Right side.

  • Left rear

    Left rear

  • Left front

    Left front

  • Right front

    Right front

  • Right rear

    Right rear

Measurements

These are examples of measurements with a 7B85 in the Horizontal A and a 7B80 in the Horizontal B compartment (of a 7904).

Horizontal mode is set to alternating to show the pulse signal being triggered (A) and the delayed/magnified part (B).

  • Measuring rise time of a pulse. Delayed signal is scaled for 0-100% on graticule. Delay time is adjusted so the trace crosses the 10% level on the center line. Delta time is adjusted so the delta-delayed trace crosses 90% on the same vertical line. Delta time readout indicates rise time directly.

    Measuring rise time of a pulse. Delayed signal is scaled for 0-100% on graticule. Delay time is adjusted so the trace crosses the 10% level on the center line. Delta time is adjusted so the delta-delayed trace crosses 90% on the same vertical line. Delta time readout indicates rise time directly.

  • Measuring rise time of a pulse. Same as before, rise time increased to 10 ns (HP8112A generator).

    Measuring rise time of a pulse. Same as before, rise time increased to 10 ns (HP8112A generator).

  • Pulse width measurement. Delayed signal and delta-delayed trace cross at 50%. Delta time readout indicates pulse width directly.

    Pulse width measurement. Delayed signal and delta-delayed trace cross at 50%. Delta time readout indicates pulse width directly.

  • Pulse period measurement. Delta time is adjusted to overlay the delayed trace with one delayed by an additional period. In this picture, the two traces do not yet overlay exactly.

    Pulse period measurement. Delta time is adjusted to overlay the delayed trace with one delayed by an additional period. In this picture, the two traces do not yet overlay exactly.

  • Pulse period measurement. Delayed trace overlays with one delayed by an additional period, delta time reads pulse period.

    Pulse period measurement. Delayed trace overlays with one delayed by an additional period, delta time reads pulse period.

Components

Some Parts Used in the 7B85

Part Part Number(s) Class Description Used in
155-0049-00 155-0049-00 • 155-0049-01 • 155-0049-02 Monolithic integrated circuit sweep control with lockout 335 • 464 • 465 • 466 • 475 • 475A • 475M • 485 • 5B31 • 5B40 • 5B52 • 5B42 • 5B44 • 7B53A • 7B80 • 7B85 • 7B87 • 7B92A • 7B90P • 7B10 • 7B15 • SC502 • 7B42N • AN/USM-281C • 067-0657-00
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
155-0109-00 155-0109-00 • 155-0109-01 Monolithic integrated circuit trigger 5B25N • 5B31 • 5B40 • 5B42 • 5B44 • 5S14N • 7B50A • 7B53A • 7B80 • 7B85 • 7B87 • 7B81P • 7B90P • 7S14 • 7612D • SC502 • SC503 • SC504
155-0126-00 155-0126-00 Monolithic integrated circuit trigger source selector and P-P auto amplifier 7B50A • 7B80 • 7B85 • 7B87 • 7B81P • 7B90P
155-0171-00 155-0171-00 Monolithic integrated circuit four-decade counter, latch and D/A converter 7B85 • 7D01 • 7D12 • 7D15 • 7J20
155-0185-00 155-0185-00 Monolithic integrated circuit four-digit counter, latch and D/A converter/DVM 7B15 • 7B85 • 7B87
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