221

The Tektronix Type 221 is a miniature 5 MHz analog scope introduced in 1973.

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5 MHz miniature analog scope Tektronix 221 Produced from 1973 to (?) Manuals Tektronix 221 Manual (PDF) (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

It has a switching power supply and built-in rechargeable batteries (which are a maintenance issue). It has a transformer-coupled trigger circuit which would seem to preclude DC level-based triggering. The trigger circuit uses a 1N3713 1mA tunnel diode. The vertical output amplifier that drives the CRT plates is two opamps made from discrete transistors. One drives the top deflection plate and the other drives the bottom plate.

Specifications

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Pictures

Front
Panel of 221
Probe of 221
221 with orginal bag
221 on top of 565