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 1975 to 1991 Manuals Tektronix 221 Manual (PDF) Tektronix 221 Manual (PDF, unlocked) Tektronix 221 Manual (PDF, OCR, bad-OCR) Mod 290A Single Sweep Modification Insert (PDF) (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

Key Specifications

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Internals

The 221 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 1 mA 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.

The power supply in 221 uses the 120-0876-00 transformer.

MOD 290A is found on a version made for IBM, which adds a Single Sweep function, and a "Property of IBM" engraving.

Pictures

Front
Panel of 221
Probe of 221
221 with orginal bag
221 on top of 565
MOD 290A variant for IBM
MOD 290A variant for IBM