7A26: Difference between revisions

Revision as of 12:06, 5 February 2020

Template:Plugin Sidebar 2 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-ins, 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 the conductive traces on 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

Front panel
left side
right side
Cartoon in schematic: The 7A26 Sharp Shooter

@@ Line 20: / Line 20: @@
 {{BeginSpecs}}
 {{Spec | Bandwidth |200 MHz}}
-{{Spec | Input impedance | 1 M&Omega; || 20 pF }}
+{{Spec | Input impedance | 1 MΩ // 22 pF }}
 {{Spec | Deflection factor | 5 mV/Div – 5 V/Div in 1–2–5 sequence }}
 {{Spec | Features | Bandwidth limiting switch (20 MHz) }}