565

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10 MHz dual-beam scope Tektronix 565 Produced from 1962 to (?) Manuals Tektronix 565 Manual (DjVu) Tektronix 565 Manual (PDF) (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

The Tektronix Type 565 is a dual-beam scope that takes two 2-series or 3-series vertical plug-ins. It was introduced in 1963.

A rackmount version, the RM565, was also produced. Aside from being dual-beam, the 565 is unusual among the other 560-series scopes in the fact that it (the mainframe) has built-in trigger, sweep, and horizontal amplifier circuits.

Specifications

The vertical characteristics are mostly determined by the vertical plug-ins.

The fastest sweep is 1 μs/div (100 ns/div with 10x horizontal magnification enabled). The sweep delay can be adjusted over a range from 10 μs to 50 seconds.

Power consumption, including plug-ins, is about 600 watts, maximum.

The internal calibrator produces a 1 kHz square wave with amplitude selectable in decade steps from 1 mV to 100 V.

Circuits

The 565 uses the T5650 CRT.

Vertical Signal Path

As is usual for 560-series scopes, the vertical deflection plates of the CRT are driven directly, differentially, by pins 17 and 21 of the vertical plug-in. The left plug-in bay is for the lower beam and the right plug-in bay is for the upper beam.

A 0.7—3 pF trimmer capacitor is connected immediately behind each of the plug-in connectors, and allows for the mainframe to be calibrated so that plug-ins can be interchanged without requiring the high-frequency compensation of the system to be readjusted. The capacitance seen by the plug-in driving the scope should be 14.3 pF for either beam.

There is no trigger pickoff in the vertical signal path of the 565. That function is performed by the plug-ins.

Trigger and Sweep

The triggering signal comes from pin 11 on the plug-ins, is amplified by a 12AT7-based cathode follower, and sent to "TRIGGER" switches. From there, the trigger signal is sent through a 6DJ8-based differential amplifier and then is discriminated by a 6DJ8-based Schmitt trigger.

The 565 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.

Calibrator

The calibrator is an astable multivibrator formed by one half of a 12AT7 and a 6AU6. The other half of the 12AT7 serves as the output cathode follower for the calibrator.

Comparison with the 556

The 565 appears similar to the 556, but is different in many ways. The 556 uses tunnel diodes for triggering, while the 565 uses tubes. The 556 uses letter-series and 1-series plug-ins while the 565 uses 560-series plug-ins. Moreover, the bandwidth of the 556 is specified as 50 MHz, while the bandwidth of the 565 is specified as 10 MHz. Subjectively, the trace of the 565 is very sharp, sharper than the trace of the 556.