EGT for mixture setting

[David M Parrish]

> Is it practical to, put the cold junction into a lot of insulation, eg
> shove it into a giant block of polystyrene foam , or in a thermos

Nothing that extreme is needed. For accuracy, the cold junction has to 
be in ice, since the voltage output depends on the temperatures of 
both junctions. But if you don't care about absolute accuracy, you don't 
have any cold junction compensation at all. That's how aircraft EGT's 
are done. They just add a fudge factor to the meter markings, 
assuming  the cold end will be at some reasonable cabin temp.

If you want your EGT's to be accurate down to freezing, you can use
an Analog Devices AD594. It's a thermocouple amp with built in ice 
point compensation and runs about ten bucks US.

---
David Parrish
EGT at sixty-seven degrees?
Hmmm. I thought that engine
was running awfully quiet...
 average cabin temp