Nascarcamper

While we are on the subject or EGT probes. Can I hook up two gauges to one probe?? I'm getting ready to install a TST PMCR with gauges, I already have gauges, can I hook two together off one probe?

phox_mulder

Probes are usually matched to the guage, or rather, the amplifier box.

I've heard of people hooking 1 guage to 2 probes, pre and post turbo,
but never the other way around.


phox

doug

no, don't do it. the error you will introduce is unknown but guarenteed to be in the wrong direction (gauge will read lower than actual). there are two issues:

1. like phox said, the gauge is matched (calibrated) to the probe. yea, all type K wires are electrically the same, but the gauge has to make a calibration assumption about ambient temperature and the location of the "2nd" probe (where type K wire turns into ordinary copper wire)

2. if you put two gauge faces onto the same type K wire, the electrical combination of both guages on there seeing each other will probably destroy the accuracy of either one.

Car_nut57

Doug is absolutely correct. Also don't consider a switch to go back and forth either as the switch contacts will throw the gauge reading off as well.

doug

right-o. however, there are two acceptable ways to switch between two thermocouples and one gauge face:

1. Switch AFTER the type K wire has been terminated into orginary copper wire. if you insert a switch into type K wire, the switch itself will create the K-copper junction and throw everything off. But if you switch copper wire there is no problem. Westach supports this configuration in their gauges. use a double pole switch so that the two lead wires of each thermocouple switch together. But both thermocouples have to be identical and built for the same gauge face in order for each to be calibrated correctly.

2. Switch with a type K switch. this is a switch that is made entirely of type K contact material. such switches are used reliably and accurately in industrial applications to switch one gauge between many thermocouples. But such switches are expensive and bulky, and just not practical for us.