7A18: Difference between revisions
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The 200 MHz [[7A26]] and 400 MHz [[7A24]] share the same front panel layout and operation. | The 200 MHz [[7A26]] and 400 MHz [[7A24]] share the same front panel layout and operation. | ||
The 7A18 uses the [[M036|M36]] channel switch IC for the vertical and trigger signals. | |||
{{BeginSpecs}} | {{BeginSpecs}} | ||
Revision as of 10:39, 30 October 2020
The Tektronix 7A18 is a general-purpose 75 MHz dual-trace vertical plug-in for 7000-series scopes. Model 7A18N is identical except it omits the readout circuits.
Option 06 (first offered in 1975 catalog) adds offset voltage controls giving ±200 Div offset range. This option replaces the IDENTIFY buttons with DC offset controls and adds a fourth "DC offset" position to the input coupling switch.
The 200 MHz 7A26 and 400 MHz 7A24 share the same front panel layout and operation.
The 7A18 uses the M36 channel switch IC for the vertical and trigger signals.
Key Specifications
| Input impedance | 1 MΩ // 20 pF |
|---|---|
| Deflection | 5 mV/div to 5 V/div in 1–2–5 sequence, 2% |
| Bandwidth | 0 – 75 MHz (DC), 10 Hz – 75 MHz (AC) |
| Noise | < 300 μV in 5 mV/Div |
| Option 06 offset range | ±200 Div equiv. from ±1 V in 5 mV/Div range up to ±200 V in 1 V/Div range (above that limited by maximum input voltage) |
| Features |
|
| Weight | 1.4 kg |
Prices
| Year | 1971 | 1976 | 1980 | 1984 | 1990 |
|---|---|---|---|---|---|
| Catalog price | $535 | $615 | $915 | $1,250 | $1,790 |
| 2018 value | $3,300 | $2,700 | $2,770 | $3,000 | $3,420 |
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.
Pictures
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7A18 Front
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7A18A Front
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7A18A left side. The step attenuators can be seen on the left, the amplifier board on the right.
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7A18A right side. The circuit boards on top carry the readout circuitry.
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7A18 attenuator opened. One of the attenuation R/C modules has been unplugged to reveal the switch contacts.
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A 7603 with two 7A18s
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7A18 in 7613 mainframe
Option 06
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7A18A Opt.06 Front. AC/GND/DC switches have an extra rightmost "DC Offset" position enabling the offset controls.
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7A18A Opt.06 left side (rear). Note the two blue 10T-potentiometers for offset voltage adjustment.
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7A18A Opt.06 - offset controls take the place of the Identify buttons on the standard model.
