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The Tektronix 575 is a curve tracer for transistors, introduced in March 1957. It can be thought of as being composed of three modules: an X-Y display, a step source, and a collector sweep source.


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X-Y display

The vertical and horizontal amplifiers are very similar, using the two halves of a 6CG7 dual-triode tube as the output amplifier. The CRT has -1700 V on the cathode and +2500 V on the anode. The HV power supply uses two 5642 rectifier tubes.

It is possible to use the 575 as an X-Y monitor. The vertical and horizontal range switches have settings for external input, at 0.1 V/div sensitivity.

Step Source

This uses a gated Miller integrator to generate controlled steps. The result is a staircase waveform, which generates different traces in the the family of I-V curves of the transistor.

Power Supplies

The 575 contains three separate power supplies:

  • Main Power Supply using T601 (120-095 and, later, 120-0095-01),

supplying power to the amplifiers and step generator in the 575

  • High-voltage, using T801, supplying the CRT voltages, +2300 V for the CRT anode and -1700 V for the CRT cathode
  • Collector sweep, using T701 (a variac) and T702, supplying the collector current to the device under test

Collector Sweep

Power from the mains goes through an isolation transformer and a variac and is rectified by germanium diodes to produce the collector sweep voltage. The isolation transformer has two pairs of secondary taps, one for high voltage (0 to 200 V) and low current, the other for low voltage (0 to 20 V) and high current. The maximum power that can be delivered to the transistor in either mode is approximately 200 Watts.

575 with Mod 122C has extended collector sweep voltage to 400 V.


Early 575 versions used selenium rectifiers. A kit for conversion to silicon diodes was available and is documented in the back of the manual.

The 575 has a thermal cutoff.

Type 175 High Current Adaptor

575 on top of a 175

The 575 can be paired with a 175 for high current device measurements.




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