SIZE 20 MIL-SPEC SOCKET THERMOCOUPLE CHROMEL

710103 — Size 20 Chromel Thermocouple Socket (Female) Contact for Mil-spec (MS connector) Connectors

The 710103 is a size 20 socket (female) thermocouple contact in Chromel alloy for use in mil-spec MS connector series for Type K thermocouple circuit connections at ECU thermocouple inputs, pyrometer interfaces, and EGT monitoring data acquisition systems in motorsport applications. In a Type K thermocouple circuit, Chromel forms the positive (+) leg of the thermocouple pair. This contact must be used in the correct polarity position alongside a matching Alumel contact to produce a valid Type K temperature signal. It is essential that thermocouple-alloy contacts are used at every connection point in a thermocouple circuit — substituting a standard copper or tin-plated contact at any junction introduces a parasitic thermoelectric EMF that degrades measurement accuracy.

What Is a Type K Thermocouple?

A Type K thermocouple is the most widely used thermocouple type in motorsport exhaust gas temperature (EGT) monitoring and precision engine temperature measurement. It consists of two dissimilar alloy conductors — Chromel (positive) and Alumel (negative) — that generate a thermoelectric voltage proportional to the temperature difference between the measurement junction (the probe tip) and the reference junction (at the measurement instrument). The Type K pair covers a temperature range of approximately −200°C to +1350°C and is compatible with the pyrometer inputs and EGT channels of all major motorsport ECUs and data acquisition systems.

Chromel Alloy — Polarity and Identification

Chromel is the positive (+) conductor material in a Type K thermocouple pair. Using the correct chromel socket contact ensures the positive polarity of the thermocouple circuit is correctly terminated at the connector, maintaining the polarity integrity that is essential for accurate temperature readings. Reversed polarity in a Type K circuit causes the measurement output to read below ambient — a diagnostic indicator of incorrect polarity connection.

Size 20 Contact — Application Context

Size 20 is compatible with the standard contact positions in MS3470, MS3474, and MS3456/MS3450 series circular connectors. This contact size is used when routing a thermocouple circuit through a mil-spec circular connector on a motorsport bulkhead or chassis feedthrough.

Critical: Thermocouple Contact Discipline

Using thermocouple-alloy contacts at every connection point in the thermocouple circuit is a mandatory requirement for accurate measurement. At any junction where a thermocouple wire connects to a standard copper contact, a new thermoelectric EMF is generated at that junction — adding or subtracting a temperature-equivalent error from the final reading. For a motorsport EGT circuit, this means both the positive (Chromel) and negative (Alumel) thermocouple contacts must be used in every connector the circuit passes through, from the EGT probe to the data acquisition instrument or ECU input. The mating pair must always be Chromel-to-Chromel and Alumel-to-Alumel through every connector junction.

Available from Arctic Performance Parts

Arctic Performance Parts stocks Chromel and Alumel thermocouple contacts in both size 20 and size 22, for mil-spec MS connectors and Deutsch Autosport connectors, covering the full Type K EGT monitoring circuit contact requirement for motorsport harness builds. Supporting race engine builders, data acquisition specialists, and motorsport workshops across Norway, Sweden, and Denmark. Lead time is 1–2 weeks for quantities beyond current stock.