7A26
The Tektronix 7A26 is a 200 MHz dual-trace vertical plug-in for 7000-series scopes. Designed by Tom Rousseau, it was the most successful 7000 series plug-in, with over 120,000 units produced.
The 75 MHz 7A18 and 400 MHz 7A24 share the same front panel layout and operation.
Key Specifications
| Bandwidth | 200 MHz |
|---|---|
| Input impedance | 1 MΩ // 22 pF |
| Deflection factor | 5 mV/Div – 5 V/Div in 1–2–5 sequence |
| Features | Bandwidth limiting switch (20 MHz) |
Internals
Controls layout and internal construction is very similar to the 75 MHz 7A18. Whereas the 7A18 is a discrete design, the 7A26 uses Tek-made differential amplifier ICs 155-0078-xx.
The 7A26 does not use the ±50 V supplies provided by the mainframe.
Repair issues
The pins of the attenuator modules are connected to conductive traces on the ceramic substrate inside by low-temperature soldering, which can go bad. Re-seating the module can temporarily restore the internal contact but will usually not fix the problem permanently. Repair is possible by opening the click-locked lid and carefully resoldering.
Links
Pictures
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Front panel
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left side
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right side
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Cartoon in schematic: The 7A26 Sharp Shooter
Custom ICs used in the 7A26
| Page | Model | Part nos | Description | Designers | Used in |
|---|---|---|---|---|---|
| 155-0078-00 | M084 | 155-0078-xx • 155-0273-00 • 155-0274-00 | broadband amplifier | John Addis | 464 • 465 • 466 • 468 • 475 • 475A • 475M • 485 • 7834 • 7844 • 7854 • 7904 • R7903 • R7912 • 7912AD • 7912HB • 7104 • 7A16A • 7A16P • 7A24 • 7A26 • 7A42 • 067-0587-01 • 067-0680-00 • AM503 • PG502 • PG508 • DC510 • DC5010 • FG5010 |