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Tektronix Type 81
Plugin Adapter
Type 81 with a 1A2 in a 585A

Compatible with 580-series scopes

Produced from 1960 to 1972


Manuals – Specifications – Links – Pictures

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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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.


Type 81

Type 81A

Some Parts Used in the 81

Page Class Description Used in
12AU6 Vacuum Tube (Pentode) RF pentode 81 112 512 556 575 545 549 581 585 A B C G K H L M N O R S Z
6DJ8 Vacuum Tube (Dual Triode) dual triode 80 132 161 310A 316 317 3A75 502 502A 503 504 515 516 519 526 529 RM529 533 535 536 543 544 545 545A 545B 546 547 549 555 556 565 581 581A 585 585A 661 2A60 63 2A63 3A7 3A8 1121 1A4 67 81 82 86 3B1 3B4 1S1 B O W Z Telequipment S32A Telequipment D52 Telequipment TD51 Telequipment S52 Telequipment S51 Telequipment Type A
6GM8 Vacuum Tube (Dual Triode) dual triode 81 516 S

Some Parts Used in the 81A

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