31,820
edits
m (→Measurements) |
No edit summary |
||
(13 intermediate revisions by 2 users not shown) | |||
Line 5: | Line 5: | ||
caption=Tektronix 7B85 Delaying Timebase plug-in| | caption=Tektronix 7B85 Delaying Timebase plug-in| | ||
introduced=1976 | | introduced=1976 | | ||
discontinued= | discontinued=1990 | | ||
series=[[7000-series scopes]]| | series=[[7000-series scopes]]| | ||
manuals= | manuals= | ||
* [http://bama.edebris.com/download/tek/7b85/Tektronix-7B85%20Delaying%20Time%20Base.pdf Tektronix 7B85 Manual (PDF)] | * [http://bama.edebris.com/download/tek/7b85/Tektronix-7B85%20Delaying%20Time%20Base.pdf Tektronix 7B85 Manual (PDF)] | ||
* [ | * [https://w140.com/smb/7b85_sm.pdf Tektronix 7B85 Manual (OCR, PDF)] | ||
}} | }} | ||
The '''Tektronix 7B85''' is a 400 MHz delaying timebase for [[7000-series scopes]], typically the 7800 Series, e.g. [[7844]]. | 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 | 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. | |||
The [[7B85]]/[[7B80]] combination was introduced in 1976 to replace the 200 MHz [[7B71]]/[[7B70]] that had no digital delay read-out. | |||
{{BeginSpecs}} | {{BeginSpecs}} | ||
Line 35: | Line 31: | ||
The 7B85 uses a [[155-0185-00]] digital voltmeter IC (U686). | 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 ramp has reached a control voltage, set by the front panel knobs on the 7B85. | 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 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 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. | |||
Another way of setting up a precisely delayed timebase is to use a [[7D11]] digital delay module, | |||
or even a time mark generator such as the [[180A]], [[181]], [[184]], or [[2901]]. | |||
The 7B85 uses the +50 V supply provided by the mainframe. | |||
==Links== | |||
* [[Media:Tekscope_1976_V8_N1.pdf|Delta time measurement for the 7000 series. Tekscope Vol.8 No.1, 1976]] | |||
* [https://m.youtube.com/watch?v=Hz-gF_XSj9w Demonstration of delay and delta time measurement on a 7B85] | |||
==Pictures== | ==Pictures== | ||
Line 47: | Line 52: | ||
===Hardware=== | ===Hardware=== | ||
<gallery> | <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> | </gallery> | ||
Line 58: | Line 69: | ||
Horizontal mode is set to alternating to show the pulse signal being triggered (A) and the delayed/magnified part (B). | Horizontal mode is set to alternating to show the pulse signal being triggered (A) and the delayed/magnified part (B). | ||
<gallery> | <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> | </gallery> | ||
Line 68: | Line 79: | ||
[[Category:7000 series horizontal plugins]] | [[Category:7000 series horizontal plugins]] | ||