565

The Tektronix Type 565 is a dual-beam scope that takes two 2-series or 3-series vertical plug-ins. Two trigger and sweep modules are contained in the mainframe. The 565 is similar to the 556, but with much less bandwidth and without tunnel diode triggering. A rackmount version, the RM565, was also produced. The triggering signal passes through a 6DJ8-based differential amplifier and then is discriminated by a 6DJ8-based Schmitt trigger. As is usual for 560-series scopes, the vertical deflection plates of the CRT are driven directly by the vertical plug-in. Aside from being dual-beam, the 565 is unusual among the other 560-series models in the fact that it has built-in trigger, sweep and horizontal amplifier circuits. It is also unusual in that it employs a tunnel diode in the trace intensification circuit. The tunnel diode forms as a bistable multivibrator: kick it one way and it turns on and stays on, kick it the other way and it turns off and stays off.