CHT Thermocouple Probe Type?

AA-00227

Most Aviation CHT probes are either Type-K or Type-J thermocouples.

All CHT probes sold by MGL Avionics are Type-K. Many CHT probes available in the US are type-J. Please contact manufacturer to find out what type they are.

If you use the wrong type in your instrument setup, you will get inaccurate readings.

Type-K thermocouples normally have Red and Yellow wires.
Type-J thermocouples normally have Black and White wires.

Note that the polarity of Type-K Thermocouples is not intuitive, as Red is Negative:

TYPE-K (typical):
YELLOW = POSITIVE
RED = NEGATIVE


Note that the polarity of Type-J Thermocouples is not intuitive, as Black is often Positive:

TYPE-J (typical):
BLACK = POSITIVE
WHITE = NEGATIVE

Read more about thermocouples here:
http://en.wikipedia.org/wiki/Thermocouple