7B92: Difference between revisions
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|discontinued=1992 | |discontinued=1992 | ||
|series=7000-series scopes | |series=7000-series scopes | ||
|designers=Bill DeVey;Les Larson;Val Garuts | |designers=Bill DeVey;Les Larson;Val Garuts;Bruce Hofer | ||
|manuals= | |manuals= | ||
'''7B92''' | '''7B92''' | ||
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It was introduced along with the [[7904]] mainframe in 1972. In 1976, it was updated as the 7B92A. | It was introduced along with the [[7904]] mainframe in 1972. In 1976, it was updated as the 7B92A. | ||
According to [[Media:Tekscope 1971 V3 N4 Jul 1971.pdf|July 1971 Tekscope]], it was designed by [[Les Larson]] and [[Bill DeVey]]. | According to [[Media:Tekscope 1971 V3 N4 Jul 1971.pdf|July 1971 Tekscope]], it was designed by [[Les Larson]] and [[Bill DeVey]]. On the 7B92A, Larson served as the project engineer and worked on the trigger circuits while [[Bruce Hofer]] designed the sweep generator, delay pickoff, and output amplifier. | ||
An "HF Sync" triggering mode is provided in which the trigger level control varies the frequency of a built-in oscillator to lock on to the input for input signals from 100 to 500 MHz, providing higher sensitivity than the direct trigger (which is specified up to 500 MHz as well). | An "HF Sync" triggering mode is provided in which the trigger level control varies the frequency of a built-in oscillator to lock on to the input for input signals from 100 to 500 MHz, providing higher sensitivity than the direct trigger (which is specified up to 500 MHz as well). | ||
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==Internals== | ==Internals== | ||
The 7B92 uses a discrete trigger circuit containing [[152-0177-02]] [[tunnel diodes]]. Up to serial number B069999, the 7B92A used a trigger circuit with [[155-0061-00]] amplifiers and [[152-0177-02]] tunnel diodes. After that, the 7B92A used a [[155-0061-00]] trigger amplifier followed by a [[155-0150-00]] trigger detector. | The 7B92 uses a discrete trigger circuit containing [[152-0177-02]] [[tunnel diodes]]. Up to serial number B069999, the 7B92A used a trigger circuit with [[155-0061-00]] amplifiers and [[152-0177-02]] tunnel diodes. After that, the 7B92A used a [[155-0061-00]] trigger amplifier followed by a [[155-0150-00]] trigger detector. | ||
[https://vintagetek.org/years-at-tektronix-hofer/ According to Bruce Hofer], early 7B92 models exhibited sweep anomalies especially near the start of the sweep, and after trying to fix these he convinced management that a redesign was needed. This resulted in [[Petent US 4009399A]], the [[7B92A]] update, and the [[067-0657-00]] calibration fixture. | |||
The 7B92A uses one other custom IC, the [[155-0049-00|155-0049-xx]] sweep control circuit. The internal jumper for mainframe selection (7800/7900/7100 vs. slower) actually increases the minimum holdoff time on the slower mainframe selection by adding a 214 pF capacitor (C307 for 7B92, C835 for 7B92A) to pin 8 of the sweep control IC [[155-0049-00|155-0049-xx]] in parallel to the existing capacitors. This increases the minimum pulse width of the holdoff signal on [[7000_Series_plug-in_interface|pin B4]] so that the sweep logic of slower mainframes can handle it properly. The effect of this jumper is only noticeable for sweep speeds of 20 μs/Div and faster, since there the smallest shunt capacitance is used on pin 8, and the holdoff time is minimal. | The 7B92A uses one other custom IC, the [[155-0049-00|155-0049-xx]] sweep control circuit. The internal jumper for mainframe selection (7800/7900/7100 vs. slower) actually increases the minimum holdoff time on the slower mainframe selection by adding a 214 pF capacitor (C307 for 7B92, C835 for 7B92A) to pin 8 of the sweep control IC [[155-0049-00|155-0049-xx]] in parallel to the existing capacitors. This increases the minimum pulse width of the holdoff signal on [[7000_Series_plug-in_interface|pin B4]] so that the sweep logic of slower mainframes can handle it properly. The effect of this jumper is only noticeable for sweep speeds of 20 μs/Div and faster, since there the smallest shunt capacitance is used on pin 8, and the holdoff time is minimal. | ||
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==Links== | ==Links== | ||
* [https://www.youtube.com/watch?v=uBeYAcD7Dds Zenwizard Studios - Tektronix 7B92A Calibration and Checkin] | * [https://www.youtube.com/watch?v=uBeYAcD7Dds Zenwizard Studios - Tektronix 7B92A Calibration and Checkin] | ||
* [[Bruce Hofer]], ''[https://vintagetek.org/years-at-tektronix-hofer/ My Years at Tektronix] | |||
==Pictures== | ==Pictures== | ||