The International Cessna^® 170 Association

I have a bunch of that stuff, acquired along the way and I should really just chuck it. Electronics International is the stuff I use and zero problems.

The problem with Alcor gauges is that they use galvanometer movements, where the needle position is proportional to current. But thermocouples are voltage-output devices, so the gauge calibration depends on the total resistance of the probe, connectors, wire, and gauge internal calibration resistor.