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.

Tektronix Type 81
Plugin Adapter Type 81 with a 1A2 in a 585A Compatible with 580-series scopes Produced from 1960 to 1972 Manuals Tektronix Type 81 Manual (PDF) Tektronix Type 81A Manual (PDF) Factory Calibration Procedures Type 81 FCP (PDF) Type 81A FCP (PDF) (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

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.

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.