P6042

Tektronix P6042
DC−50 MHz current probe P6042 complete Compatible with 50 Ω scope inputs Produced from 1967 to (?) Manuals Tektronix P6042 Manual Tektronix P6042 Calibration Procedure

Manuals – Specifications – Links – Pictures

The Tektronix P6042 is a DC to 50 MHz current probe introduced in 1967. It was designed by Cal Hongel.

The sensor contains a current transformer for HF and a hall effect sensor for LF/DC components. The amplifier combines DC/LF and HF signals.

The AM503, introduced about a decade later, is a redesign of the P6042 with removable probes.

Key Specifications

Bandwidth	DC to 50 MHz (−3 dB)
Rise time	7 ns
Ranges	1 mA/div to 1 A/div (1–2–5) with scope in 50 mV/div
Output	to 50 Ω scope input at 50 mV/div
Maximum input	10 A DC+peak AC in 5 mA to 1 A ranges, 0.5 A in 1 mA and 2 mA ranges
Power	90-136 or 180-272 V, 20 W

Internals

Locking the probe requires pushing past the resistance felt when the core almost closes. This engages a mechanism that firmly presses both core halves together, and extinguishes the "Probe unlocked" indicator.

The P6042's core halves are precision lapped and potted with epoxy. They have Mu-metal screening. The lower (fixed) core also contains the Hall element. Unfortunately, the P6042 probe is quite sensitive mechanically, and in many units offered for sale, the cores are damaged.

The amplifier front-end is constructed using a 156-0014-00 differential amplifier integrated circuit, labelled "M18", which cross-references to a long-obsolete Teledyne "831-BE". Jim Williams' Applicaion Note 61 contains a replacement circuit using LT1228 opamps (page 19).