7B92: Difference between revisions

Latest revision as of 07:32, 12 December 2023

Tektronix 7B92
500 MHz dual timebase 7B92 front Compatible with 7000-series scopes Produced from 1971 to 1976 Manuals 7B92 Tektronix 7B92 Operators Manual Tektronix 7B92 Service Manual (OCR, uncut schematics) Tektronix 7B92 Circuit Description Supplement (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

The Tektronix 7B92 is a 500 MHz dual timebase plug-in for 7000-series scopes. It was introduced along with the 7904 mainframe in 1972. According to July 1971 Tekscope, the 7B92 was designed by Les Larson and Bill DeVey.

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).

Internal jumpers are provided to configure the 7B92 for operation in 7800/7900 vs. slower mainframes, and to select whether the variable control affects the delaying or the delayed time base.

As a dual time base, the 7B92 uses the top field in the 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 7B92 has no magnifier function but its regular sweep dial setting reaches down to 500 ps/Div. It has no provision for X-Y operation.

Key Specifications

Sweep speed	0.5 ns/Div to 0.2 s/Div, 1−2−5 sequence (variable up to 0.5 s/Div)
Delay time	0 to 9.9 Div
Triggering	0.5 Div or 100 mV up to 20 MHz, 1 Div or 500 mV up to 600 MHz
Jitter	< 50 ps at 600 MHz
Ext Trig input	1 MΩ // 20 pF or 50 Ω

After the 7B92 had been in production for years, it was discovered that the 7B92's ramp generator had aberrations at the beginning of the sweep at the fastest sweep rates. Bruce Hofer recalls investigating this issue and concluding that an redesign was needed. The redesign led to the introduction of the 7B92A, Patent US 4009399A, and the 067-0657-00 calibration fixture.

Internals

The 7B92 uses a discrete trigger circuit containing 152-0177-02 tunnel diodes.

The internal jumper (J308/J309) for mainframe selection (7800/7900/7100 vs. slower) increases the minimum holdoff time on the slower mainframe selection by adding a 150 pF capacitor, C307, to pin 8 (HO TIMING) of the sweep control IC, U310 (155-0049-xx), in parallel to the existing capacitors. This increases the minimum pulse width of the holdoff signal on 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 at those sweep speeds the smallest shunt capacitance is used on pin 8, and the holdoff time is minimal.

Pictures

7B92 front
7B92 right
7B92 left

Components

Some Parts Used in the 7B92

Part	Part Number(s)	Class	Description	Used in
155-0061-00	155-0061-00 • 155-0061-01 • 155-0061-02	Monolithic integrated circuit	trigger amplifier	7B92 • 7B92A
1N3719	152-0182-00	Discrete component	10 mA, 50 pF germanium tunnel diode	422 • 661 • 7B92 • 7B92A
SMTD998	152-0177-02	Discrete component	10 mA, 2 pF tunnel diode	067-0681-01 • 485 • 7B92 • 7B92A

@@ Line 1: / Line 1: @@
-{{Plugin Sidebar 2 |
+{{Plugin Sidebar
-title=Tektronix 7B92 |
+|manufacturer=Tektronix
-summary=500 MHz Dual Timebase |
+|type=7B92
-image=7b92a-front.jpg |
+|summary=500 MHz dual timebase
-caption=7B92A front |
+|image=Tek 7b92 front.jpg
-introduced=1971 |
+|caption=7B92 front
-discontinued=1992 |
+|introduced=1971
-series=[[7000-series scopes]] |
+|discontinued=1976
-manuals=
+|series=7000-series scopes
-* [http://bama.edebris.com/download/tek/7b92a-2/tek-7b92a.pdf Tektronix 7B92A Manual (PDF)]
+|designers=Bill DeVey;Val Garuts
-* [http://w140.com/smb/7b92_sup_sm.pdf Tektronix 7B92 Circuit Description Supplement (OCR, PDF)]
+|manuals=
-* [http://w140.com/smb/7b92_svc_sm.pdf Tektronix 7B92 Service Manual (OCR, PDF)]
+'''7B92'''
-* [http://w140.com/smb/7b92a_op_sm.pdf Tektronix 7B92A Operators Manual (OCR, PDF)]
+* [[Media:070-1401-00.pdf|Tektronix 7B92 Operators Manual]]
-* [http://w140.com/smb/7b92a_sm.pdf Tektronix 7B92A Service Manual (OCR, PDF)]
+* [[Media:070-1192-00.pdf|Tektronix 7B92 Service Manual]] (OCR, uncut schematics)
+* [[Media:070-1630-00.pdf|Tektronix 7B92 Circuit Description Supplement]]
 }}
 The '''Tektronix 7B92''' is a 500 MHz dual timebase plug-in for [[7000-series scopes]].
-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.
+According to [[Media:Tekscope 1971 V3 N4 Jul 1971.pdf|July 1971 Tekscope]], the 7B92 was designed by [[Les Larson]] and [[Bill DeVey]].
-An "HF Sync" triggering mode is provided in which the trigger level
+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).
-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).
-Internal jumpers are provided to configure the 7B92 for operation in 7800/7900 vs. slower mainframes,
+Internal jumpers are provided to configure the 7B92 for operation in 7800/7900 vs. slower mainframes, and to select whether the variable control affects the delaying or the delayed time base.
-and to select whether the variable control affects the delaying or the delayed time base.
-As a dual time base, the 7B92 uses the top field in the [[7000 series readout system|display readout]]
+As a dual time base, the 7B92 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.
-for the sweep speed of the main and the bottom field for the delayed time base.  The delay time
+The delay time can only be read from the 10-turn analog dial.
-can only be read from the 10-turn analog dial.
-The 7B92 has no magnifier function but its regular sweep dial setting reaches down to 500 ps/Div.
+The 7B92 has no magnifier function but its regular sweep dial setting reaches down to 500 ps/Div.  It has no provision for X-Y operation.
-It also 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 | 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 | 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 | 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 | Jitter         | < 50 ps at 600 MHz }}
 {{Spec | Ext Trig input | 1 MΩ // 20 pF or 50 Ω }}
 {{EndSpecs}}
+After the 7B92 had been in production for years, it was discovered that the 7B92's ramp generator
+had aberrations at the beginning of the sweep at the fastest sweep rates.
+[https://vintagetek.org/years-at-tektronix-hofer/ Bruce Hofer recalls] investigating this issue and
+concluding that an redesign was needed.
+The redesign led to the introduction of the [[7B92A]], [[Patent US 4009399A]],
+and the [[067-0657-00]] calibration fixture.
 ==Internals==
-The 7B92 uses a discrete trigger circuit containing [[tunnel diodes]].
+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 tunnel diodes.
+The internal jumper (J308/J309) for mainframe selection (7800/7900/7100 vs. slower)
-After that, the 7B92A used a [[155-0061-00]] trigger amplifier followed by a [[155-0150-00]] trigger detector.
+increases the minimum holdoff time on the slower mainframe selection by adding a 150 pF capacitor, C307,
-The 7B92A uses one other custom IC, the [[155-0049-00|155-0049-xx]] sweep control circuit.
+to pin 8 (HO TIMING) of the sweep control IC, U310 ([[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 at those sweep speeds the smallest shunt capacitance is used on pin 8, and the holdoff time is minimal.
 ==Pictures==
 <gallery>
 Tek 7b92 front.jpg    | 7B92 front
 Tek 7b92 right.jpg    | 7B92 right
 Tek 7b92 left.jpg     | 7B92 left
-b92a-front.jpg       | 7B92A front
-Tek 7b92a front2.jpg| 7B92A
-Tek 7b92a right.jpg   | 7B92A right
-Tek 7b92a left.jpg    | 7B92A left
-Tek 7b92a block.png  | 7B92A block diagram
-b92a-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>
+==Components==
+{{Parts|7B92}}
 [[Category:7000 series horizontal plugins]]