551

The 551 is a dual-beam scope that takes two letter-series or 1-series vertical-plug-ins. Unlike the 555, it has only one set of horizontal deflection plates. The trigger and sweep circuitry are built in to the mainframe. Like the 555, the 551 uses and external power supply unit. The external power supplies of the 555 and 551 are not interchangeable. The manual is on BAMA.

A factory modification, MOD 108A, was available for increasing the CRT acceleration voltage. This improved trace visibility at high sweep rates.

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  Front view.

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  External power supply.

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  Left side.

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  Right side.

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  Top view.