7B85: Difference between revisions
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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]], typically the 7800 Series, e.g. [[7844]]. | ||
The trigger circuit is similar to that of the [[7B80]]. | The trigger circuit is similar to that of the [[7B80]]. | ||
The digital delay differentiates the 7B85 from the [[7B80]]. The [[7B87]] is similar to the 7B85 but provides | The digital delay differentiates the 7B85 from the [[7B80]]. The [[7B87]] is similar to the 7B85 but provides | ||
an acquisition clock for a digital storage mainframe instead of a delay. | an acquisition clock for a digital storage mainframe instead of a delay. | ||
==Specifications== | |||
{{BeginSpecs}} | |||
{{Spec | Sweep | 1 ns to 5 s/div }} | |||
{{Spec |Triggering | to 400 MHz }} | |||
{{Spec | Features | | |||
* Variable Trigger Holdoff | |||
* Peak-to-peak Auto Triggering | |||
}} | |||
{{EndSpecs}} | |||
==Internals== | |||
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. | ||
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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]]. | 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]]. | ||
==Pictures== | ==Pictures== | ||
Revision as of 22:48, 25 August 2014
The Tektronix 7B85 is a 400 MHz delaying timebase for 7000-series scopes, typically the 7800 Series, e.g. 7844. The trigger circuit is similar to that of the 7B80. The digital delay differentiates the 7B85 from the 7B80. The 7B87 is similar to the 7B85 but provides an acquisition clock for a digital storage mainframe instead of a delay.
Specifications
Key Specifications
| Sweep | 1 ns to 5 s/div |
|---|---|
| Triggering | to 400 MHz |
| Features |
|
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, or even a time mark generator such as the 180A, 181, 184, or 2901.
Pictures
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Left rear
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Left front
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Right front
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Right rear
