The Tektronix 570 is a curve tracer for tubes, introduced in 1955. It sweeps the plate voltage between zero and a selectable maximum voltage while "stepping" the control grid through a set of voltages.
A selectable screen voltage is available for testing tubes with screens. The plate voltage is measured and applied to the X-axis of the display. Plate current is measured and amplified and is applied to the Y-axis of the display.
The 570 contains five transformers:
- T310: center-tapped isolation transformer for plate sweep
- T340: multitap transformer for heater voltages
- T401: multitap autotransformer for selecting peak plate voltage, feeds T310
- T501: transformer for floating supplies and screen voltage supply
- T620: transformer for 60kHz HV power oscillator for CRT voltages
The screen supply is regulated and uses a 6CD6GA tube as the series regulator.
The vertical and horizontal amplifiers are almost identical. The first stage is a differential amplifier made of two 6AU6 tubes. The second stage is a differential amplifier made of both halves of a 6BQ7A.