86
The Tektronix Type 86 is a single-input amplifier plug-in for 580-series scopes, introduced in 1963. The Type 86 in a 581, 581A, 585 or 585A mainframe oscilloscope provides a 4 nanosecond risetime (85 MHz bandwidth). The risetimes written on the front panel are those of the plugin alone.
The amplifier of the Type 86 amplifier was designed by John Gates. Wim Velsink designed the Type 86 attenuator.
The P6008 voltage probe was designed for use with the Type 86.
Units with serial numbers before 1997 use a rotary input switch for the input coupling. Starting with serial number 1997, a lever switch is used.
Key Specifications
| Input impedance | 1 MΩ // 15 pF |
|---|---|
| Bandwidth | 85 MHz at 100 mV/cm, 80 MHz at 10 mV/cm (in a 580 series mainframe) |
| Rise time | 4 ns in ×1 mode, 4.3 ns in ×10 mode (in a 580 series mainframe) |
| Deflection | ×1 mode, 100 mV/div to 50 V/div; ×10 mode, 10 mV/div to 5 V/div; 1−2−5 |
Links
Patents that may apply to 86
| Page | Title | Inventors | Filing date | Grant date | Links |
|---|---|---|---|---|---|
| Patent GB 460562A | Improvements In and Relating to Thermionic Valve Circuits | William Spencer Percival | 1935-07-24 | 1937-01-25 | Distributed amplifier • 513 • 514 • 517 • 524 • 541 • 543 • 545 • 551 • 555 • 581 • 585 • 82 • 86 • 945 |
| Patent US 2930986A | Distributed amplifier | John Kobbe • Bill Polits | 1956-02-29 | 1960-03-29 | Distributed amplifier • 513 • 514 • 517 • 524 • 541 • 543 • 545 • 551 • 555 • 581 • 585 • 82 • 86 • 945 |
Internals
The signal path in the Type 86 begins with a 7586 Nuvistor as a cathode follower, feeding a differential transistor-based stage. In ×10 gain, this is followed by three more differential transistor gain stages. Finally, a distributed amplifier with three 6DJ8s drives the mainframe interface.
As with the Type 82 plug-in, 585 non-A scopes with serial numbers before 2585 should have the back termination of the final distributed amplifier output modified to the later circuit (modification 040-275).
Prices
| Year | Catalog price | In 2026 dollars |
|---|---|---|
| 1965 | $350 | ~$3,600 |
| 1969 | $385 | ~$3,400 |
Pictures
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Late serial number Type 86 with lever input coupling switch
