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7B92A: Difference between revisions
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{{Plugin Sidebar | |||
|manufacturer=Tektronix | |||
|type=7B92A | |||
|summary=500 MHz dual timebase | |||
|image=7b92a-front.jpg | |||
|caption=7B92A front | |||
|introduced=1976 | |||
|discontinued=1992 | |||
|series=7000-series scopes | |||
|designers=Les Larson;Bruce Hofer | |||
|manuals= | |||
'''7B92A''' | |||
* [[Media:070-1752-00.pdf|Tektronix 7B92A Operators Manual -00]] (OCR) | |||
* [[Media:070-1752-01.pdf|Tektronix 7B92A Operators Manual -01]] (OCR) | |||
* [[Media:070-1751-00.pdf|Tektronix 7B92A Instruction Manual -00]] (OCR) | |||
* [[Media:070-1751-02.pdf|Tektronix 7B92A Instruction Manual -02]] (1987 rev., both circuit versions)<small> / [https://bama.edebris.com/download/tek/7b92a-2/tek-7b92a.pdf alternate copy @ BAMA]</small> | |||
}} | |||
The '''Tektronix 7B92A''' is a 500 MHz dual timebase plug-in for [[7000-series scopes]]. | |||
It was introduced 1976, replacing the [[7B92]]. | |||
The 7B92A was developed after it was discovered that the 7B92's sweep ramp generator had aberrations | |||
in its start-up at the fastest sweep rates. | |||
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). | |||
As a dual time base, the 7B92A uses the top field in the [[7000 series readout system|display readout]] | |||
for the sweep speed of the main and the bottom field for the delayed time base. | |||
The delay time can only be read from the 10-turn analog dial. | |||
The 7B92A has no magnifier function but its regular sweep dial setting reaches down to 500 ps/Div. | |||
It has no provision for X-Y operation. | |||
{{BeginSpecs}} | |||
{{Spec | Sweep speed | 0.5 ns/Div to 0.2 s/Div, 1−2−5 sequence (variable up to 0.5 s/Div)}} | |||
{{Spec | Delay time | 0 to 9.9 Div }} | |||
{{Spec | Triggering | 0.5 Div or 100 mV up to 20 MHz, 1 Div or 500 mV up to 600 MHz }} | |||
{{Spec | Jitter | < 50 ps at 600 MHz }} | |||
{{Spec | Ext Trig input | 1 MΩ // 20 pF or 50 Ω }} | |||
{{EndSpecs}} | |||
==Internals== | |||
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 [[Patent 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, C835, to pin 8 of the sweep control IC [[155-0049-00|155-0049-xx]] | |||
in parallel with 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. | |||
==Links== | |||
* [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] | |||
* [[Patent_US_4009399A| US Patent 4009399 Gated Ramp Generator]] | |||
==Pictures== | |||
<gallery> | |||
7b92a-front.jpg | 7B92A front | |||
Tek 7b92a front2.jpg | 7B92A | |||
Tek 7b92a right.jpg | 7B92A right (late S/N, [[Hypcon]]-packaged [[155-0150-00]] trigger detector circuits) | |||
Tek 7b92a left.jpg | 7B92A left (late S/N) | |||
Tek 7b92a block.png | 7B92A block diagram | |||
7b92a-triggering-974mhz.jpg | A 7B92A (B098xxx) triggering a 974 MHz sine applied to a [[7904]] mainframe via a 067-0587-02 calibration fixture (maximum triggerable frequency for this specimen). | |||
Tek7904-7a19-7b92a-1010mhz-hfsync.jpg | A 7B92A (B098xxx) displaying a 1.01 GHz sine in HF Sync mode on a [[7904]] mainframe via a [[7A19]] amplifier (maximum signal generator frequency). | |||
</gallery> | |||
{{Custom ICs|7B92A}} | |||
[[Category:7000 series horizontal plugins]] | [[Category:7000 series horizontal plugins]] | ||
[[Category:Introduced in 1976]] | [[Category:Introduced in 1976]] | ||