Mini Female Jack Thermocouple Connector - Type K

Why Thermocouple Connectors Are Alloy-Specific

A common source of measurement error in thermocouple circuits is using generic copper connectors instead of alloy-matched thermocouple connectors. The Seebeck voltage generated by a Type K thermocouple is the result of the temperature differential between the measuring junction at the probe tip and the reference junction at the instrument input.

Any electrical connection made with a different alloy — including standard copper or brass terminals — creates an unintended thermocouple junction at that point. If that parasitic junction is at a different temperature than the instrument's reference junction, it introduces a temperature-dependent voltage offset into the measurement.

The CON-FJ-MINI-K uses flat spade pins manufactured from Chromel (positive) and Alumel (negative) alloy — the same alloy pair that constitutes a Type K thermocouple element. This means the connector does not introduce additional thermoelectric error when both pins are at the same temperature. The signal passes through without introducing measurable error under isothermal conditions.

Mini vs. Standard Connector Format: Choosing the Right One

Thermocouple connectors are available in two physical sizes: mini and standard. The mini connector (used in the CON-FJ-MINI-K) is the more compact format, approximately 0.35 inches wide at the pin-mating face, and is the format used on all TSC EGT probes and CHT sensors. The standard connector is approximately 0.75 inches wide and is more common in industrial panel-mount and process control applications.

The two formats are not physically interchangeable — a mini plug will not mate with a standard jack, and vice versa.

The female jack accepts the male plug terminated to the probe or extension cable. In the standard probe-to-instrument wiring scheme, the probe terminates in a male plug, the instrument input accepts a male plug, and a female jack is used at each end of an extension cable segment to allow the circuit to be broken cleanly at those points.

Using a female jack at both ends of an extension cable — mating to male plugs at the probe and instrument — helps prevent reverse polarity connections, since the keyed flat-pin geometry is asymmetric and is designed to mate in the correct orientation.

Strain Relief Bracket Installation

The CON-FJ-MINI-K ships with a wire strain relief bracket and removable rubber bushing. The strain relief bracket is a critical installation step that is sometimes skipped, leading to connector damage at the wire entry point when the cable is repeatedly flexed.

Installing the bracket and bushing takes approximately two minutes using the assembly instructions included in the product documents and protects the connector at the point of highest mechanical stress.

For high-vibration applications — motorcycle, snowmobile, or kart installations — a silicone rubber boot is also available separately and is strongly recommended as an additional mechanical and environmental seal.

The connector is compatible with standard mini Type K thermocouple plugs and instrumentation.