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

Tektronix P6042
DC−50 MHz current probe
P6042 complete

Compatible with 50 Ω scope inputs

Produced from 1967 to (?)


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


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).


  • $525 in 1967 (~$5,500 in 2022 Dollars)


Documents Referencing P6042

Document Class Title Authors Year Links
Tekscope 1974 V6 N3.pdf Article Using your oscilloscope probe (Part 2) Riley Stock 1974