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The Tektronix 7A42 is a four-channel | {{Plugin Sidebar | ||
It supports triggering based on Boolean conditions of the four inputs. | |manufacturer=Tektronix | ||
|series=7000-series scopes | |||
|type=7A42 | |||
|summary=350 MHz four-channel logic triggered amplifier | |||
|image=Tektronix 7A42 front.jpg | |||
|caption=7A42 front view | |||
|introduced=1984 | |||
|discontinued=1990 | |||
|manuals= | |||
* [[Media:070-4285-00.pdf|7A42 Operator Manual]] (OCR) | |||
* 7A42 Service Manual | |||
** [[Media:070-4286-00.pdf|070-4286-00 Volume 1]] (OCR) | |||
** [[Media:070-4654-00.pdf|070-4654-00 Volume 2, Signature Analysis Tables]] (OCR) | |||
<small> | |||
'''ROM images''' | |||
* [[Media:160-1959-00.bin|160-1959-00.bin A8U145]] | |||
* [[Media:160-1960-00.bin|160-1960-00.bin A8U245]] | |||
* [[Media:160-1961-00.bin|160-1961-00.bin A8U340]] | |||
</small> | |||
}} | |||
The '''Tektronix 7A42''' is a four-channel 350 MHz plug-in for [[7000-series scopes]]. It is a double-wide plug-in, with signal outputs and mainframe readout only using the left slot. | |||
It was specifically designed for logic signals (TTL, ECL, CMOS) and supports triggering based on Boolean conditions of the four inputs. | |||
A fifth trace, "Trigger View", displays the trigger function output or external clock input. | |||
There are two sets of conditions, A and B, that can be individually selected or paired in an "A then B" mode called ''nested triggering'', where the occurrence of condition A arms the trigger and condition B causes the trigger to be generated. | |||
The trigger can be qualified by an external clock. A trigger filter control, variable from 0-300 ns, allows events shorter than the selected length to be suppressed. A TTL-level "reset" input will inhibit the trigger if active. | |||
Selected by an internal jumper, either the trigger signal, or the "A then B" interval, is available on a front-panel trigger output. This can e.g. be routed to a counter for time measurement or event counting. | |||
The input V/Div setting can only be seen in the mainframe's readout. | |||
There is a jumper to allow the readout to work in a [[7854]] mainframe. | |||
The trigger level is set digitally and shown on a 7-segment display. | |||
Tektronix recommended the [[P6131]], 300 MHz, 10 MΩ ×10 probe, and the [[P6230]], 1.5 GHz, 450/50 Ω ×10, variable-offset probe for ECL circuits. | |||
The [[067-1155-99]] calibration fixture is specific to the 7A42. | |||
{{BeginSpecs}} | |||
{{Spec | Bandwidth | 350 MHz }} | |||
{{Spec | Deflection | | |||
* 0.1 / 0.2 / 0.5 V/Div (TTL mode) | |||
* 20 / 50 / 100 mV/Div (ECL mode) | |||
* each direct or through 10:1 probe | |||
* always DC coupled }} | |||
{{Spec | Input impedance | 1 MΩ // 15 pF or 50 Ω}} | |||
{{Spec | Max. input voltage | | |||
* at 1 MΩ: 25 V (DC+peak AC) below 36 MHz, down to 3 V<sub>AC</sub> at 300 MHz | |||
* at 50 Ω: 5 V<sub>RMS</sub> during any 1 ms interval}} | |||
{{Spec | Trigger level | | |||
* −1.27 to +1.28 V (TTL mode) in 10 mV steps | |||
* −254 mV to +256 mV (ECL mode) in 2 mV steps (or ×10)}} | |||
{{Spec | Hysteresis | 40 mV (TTL), 8 mV (ECL) (or ×10)}} | |||
{{Spec | Features | | |||
* NiCd battery to preserve front-panel control status}} | |||
{{Spec | Weight | 2.8 kg / 6.2 lb}} | |||
{{EndSpecs}} | |||
==Links== | |||
{{Documents|Link=7A42}} | |||
==See also== | |||
* [[067-1155-99]] | |||
* [[A6701]] | |||
* [[821]] | |||
==Internals== | |||
The 7A42's functions are controlled by an [[Intel 8085]]A microprocessor, with code in three 2764 EPROMs (a fourth ROM socket is unused). The front-panel pushbuttons are handled by an Intel 8279 keyboard controller. | |||
Each of the four [[119-1517-00]] input attenuator modules contains five [[148-0145-00|148-0145-00 miniature bi-stable relay actuators]]. These have four long pins plugging in to the base board, driving two solenoids that move aa yoke which is held in the last active position by a permanent magnet. The yoke moves a pair of contact springs that directly short corresponding pads on the thick-film ceramic substrate. The relay coils are wired in a 4×5 matrix. | |||
The 7A42 contains its own switch mode PSU, based on an SG3524 controller, that generates +5 V, −2 V and −5 V from the mainframe's ±50 V rails. | |||
There is a [[7A42/Repairs|NiCd backup battery]] that allows the unit to retain its last configuration. | |||
A 555 timer implements a 15 ms "real-time clock" and watchdog reset, another drives a beeper. | |||
An internal jumper enables partial compatibility with a [[7854]] mainframe in storage mode (displaying any single channel, 1+2 in ALT, or 3+4 in ALT only). There are no restrictions with the 7854 in analog mode. | |||
==Pictures== | |||
<gallery> | <gallery> | ||
Tektronix 7A42 front.jpg | |||
Tek 7a42.jpg | |||
Tek 7a42 1.jpg | |||
Tek 7a42 2.jpg | |||
Tek 7a42 fr1.jpg | |||
Tek 7a42 fr2.jpg | |||
Tek 7a42 fr3.jpg | |||
Tek 7a42 fr4.jpg | display - four signal traces plus trigger view | |||
Tek 7a42 fr5.jpg | |||
Tek 7a42 fr6.jpg | 7A42 rear view | |||
Tek 7a42 fr7.jpg | 7A42 top view | |||
Tek-7A42-Bus.jpg | Schematic cartoon: Bus | |||
Tek-7A42-Chirp.jpg | Schematic cartoon: Chirp | |||
</gallery> | </gallery> | ||
'''Internal''' | |||
<gallery> | |||
7A42 amplifier board.jpg | amplifier board (one attenuator cover removed) | |||
Tek 7a42 fr11.jpg | amplifier board front - attenuators, amplifiers, channel switches | |||
Tek 7a42 fr12.jpg | amplifier board rear - channel switches, two 15 ns delay lines | |||
7A42 attenuator 1.jpg | attenuator, cover removed | |||
7A42 attenuator cover.jpg | attenuator cover | |||
7A42 attenuator 2.jpg | attenuator, top | |||
7A42 attenuator 3.jpg | attenuator, one relay actuator removed | |||
7A42 attenuator 4.jpg | attenuator, all relay actuators removed | |||
7A42 attenuator 5.jpg | attenuator, all relay actuators removed | |||
Tek 7a42 fr10.jpg | microprocessor board | |||
Tek 7a42 fr8.jpg | memory backup battery on microprocessor board replaced with LiIon | |||
Tek 7a42 fr9.jpg | internal switch mode PSU for digital logic supplies | |||
Tek 7a42 13.jpg | |||
Tek 7a42 14.jpg | |||
Tek 7a42 15.jpg | |||
</gallery> | |||
==Components== | |||
{{Parts|7A42}} | |||
[[Category:7000 series vertical plugins]] |