7704A

The Tektronix 7704A is a modular oscilloscope in the 7000 series that takes two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins. Its bandwidth is about 200MHz, depending on plug-ins. There was also an option (option 9) to have the bandwidth extended to 250MHz. The 7704A followed the 7704, improving on the bandwidth and introducing modularity.

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 7704A SMPS uses a custom Tek chip to implement the control functions. Since the SMPS is a kind of oscillator, 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.