I need a J-type thermocouple for the CHT on the Westach Quad gauge. I ordered 25 feet of J-type Iron/constantan thermocouple wire from Omega. That should be enough for half a dozen CHT sensors. I twisted the thermocouple wire ends together and crimped on a #6 lug. It would be best to spot weld the ends together. I'll need to do some more experimentation to try and do that. I suspect soldering might isolate the correct metals from one another creating a different reading.
Picture two shows results using a heat gun for heat and a multimeter thermocouple for comparison. The two sensors are in the foreground. The little round blob is the digital sensor passed through the home made sensor lug.
