SNIP

    Mark,

    The shielding on millivolt and milliamp wiring is either terminated at
    the  device end or the "control" end (reading end) of the circuit but
    not both OR neither, and it should be connected to the ground bus or
    terminal(s).  The shielding should be "continuous" from probe to your
    reading device/control device.  There is a quick treatise on:

    http://www.omega.com/prodinfo/Thermocouples.html

    What size was the hole you drilled (diameter) for the thermocouple you
    inserted?  I think that's pretty cool that you made your own by welding
    the bi-metal wiring together.  Never heard of anyone doing that.

    Allen

    Allen,
    There is a metal tip that fits into the exhaust header that the
    shield is attached.  I never really thought much about it, but I
    imagine that provides the ground for the shield (from the exhaust
    system to the engine block and then to ground).
         As for welding the ends of the TC wire for the CHT probes, I believe
    I got that idea from Tracy Crook.  I'm not sure he suggested using a
    TIG welder, but the idea was the same.  Worked great (price was
    right too).  So, should the tc leads be shielded? 

--------------------------------------------------------------

We used to make Thermocouples using a 'Variac", and a  pool of
mercury under oil. Insert a lead from the Variac into the mercury,
connect the other lead to the twisted together TC wire, and dip it
through the oil into the mercury. It will arc weld the TC tip, and
the oil keeps the mercury vapor down. OHSA probably would object now.

Bill Schertz



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