81
The Tektronix Type 81 is a plug-in adapter so that letter-series and 1-series plug-ins can be used in 580-series scopes.
The 81 and 81A are significantly different. Type 81 is tube-based and has a bandwidth of 33 MHz. Type 81A is solid-state and has a bandwidth of 50 MHz. The 81A was designed by John Gates.
Key Specifications
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Internals
The Type 81 contains a two-stage amplifier. The letter-series plug-in drives the input stage of the Type 81 which is high impedance (grids of a 6GM8 stage with T-coil peaking) so that the plug-in sees conditions similar to the input of a 530-, 540-, or 550-series scope. The second stage is a 6DJ8 cathode-follower, which drives the 580-series scope's 93 Ω input impedance. Type 81 also terminates the grid line of the distributed vertical amplifier (delay line driver).
Type 81A has a FET source follower pair followed by cascoded BJT amplifiers.
The Type 81 does not have a spoiler switch. The Type 81A has a spoiler switch.
Pictures
Type 81
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Type 81 Schematic
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Type 81A
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Type 81A Schematic
Components
Some Parts Used in the 81
| Part | Part Number(s) | Class | Description | Used in |
|---|---|---|---|---|
| 12AU6 | 154-0040-00 | Vacuum Tube (Pentode) | RF pentode | 81 • 112 • 1L10 • 1L20 • 1L60 • 3L10 • 512 • 556 • 575 • 545 • 547 • 549 • 581 • 585 • A • B • C • G • K • H • L • ML • M • N • O • R • S • Z |
| 6DJ8 | 154-0187-00 • 154-0305-00 | Vacuum Tube (Dual Triode) | dual triode | 132 • 161 • 310A • 316 • 317 • 502 • 502A • 503 • 504 • 506 • 515 • 516 • 519 • 526 • 529 • RM529 • 533 • 535 • 536 • 543 • 544 • 545 • 545A • 545B • 546 • 547 • 549 • 555 • 556 • 561A • 561S • 564 • 565 • 567 • 581 • 581A • 585 • 585A • 661 • 1A4 • 1S1 • 60 • 2A60 • 63 • 2A63 • 67 • 2B67 • 3A1 • 3A1S • 3A2 • 3A3 • 3A6 • 3A7 • 72 • 3A72 • 75 • 3A75 • 4S2 • 51 • 3B1 • 3B1S • 3B2 • 3B3 • 3B4 • 3M1 • 3S76 • 3T77 • 3T77A • 9A1 • 9A2 • 1121 • 80 • 81 • 82 • 86 • B • O • W • Z • Telequipment D56 • Telequipment S32A • Telequipment D52 • S-311 • Telequipment TD51 • Telequipment S52 • Telequipment S51 • Telequipment Type A • TU-4 |
| 6GM8 | 154-259 • 154-0259-00 | Vacuum Tube (Dual Triode) | dual triode | 81 • 516 • S |
Some Parts Used in the 81A