7704

The Tektronix 7704 is a four-bay mainframe introduced in 1969 that takes two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins. The rated bandwidth is 150MHz for the 7704 and 200MHz for the 7704A. There was also an option (option 9) to have the bandwidth extended to 250MHz.

The 7704 is single unit requiring only plug-ins to make it a complete scope. The 7704A has a special modular construction. At the bottom is the "acquisition unit", which contains the power supply, plug-in slots, and main interface board. On top is the "display unit", which contains the CRT, HV power supply, and output amplifiers for driving the deflection plates of the CRT. These units detach. A large multipin connector passes signals and power from the acquisition unit to the display unit. It is important not to damage this connector when assembling or disassembling the units.

An optional component, the P7001 Processing Unit, can be added to a 7704A between the acquisition unit and the display unit.

The 7704 and 7704A use switchmode power supplies (SMPS). The CRT power supply is separate from the low voltage power supply. The 7704 SMPS is all discrete. The 7704A SMPS uses a custom Tek chip to implement the control functions. An SMPS is a kind of oscillator and there is the issue of how it will start when it is first powered up. Early 7704As use a diac in the starter circuit. Later 7704As use a unijunction transistor in the starter circuit.

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  Left side of 7704 contains power supply.

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  Right side of 7704 contains readout circuitry.