Looking at your question, "Pyrometer", are you refering to an old moving coil type non-electronic meter. If so, yes adding extra resistance will cause too much Voltage drop.
Roy
The old pyrometers I remember were used with companion thermocouples and the length was critical. The analog meter was powered by the thermocouple output and the meter was calibrated to take into account the resistance of both the pyrometer movement and the thermocouple leads.
Bill
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"Why not the best?"
Jimmy Carter
The cold junction compensation in Honeywell-Brown moving coil pyrometers was a mechanical pointer showing the ambient at the pyrometer instrument. The zero setting of the moving coil was shifted by a bimetal spiral to agree with the ambient as shown by the pointer on the main temperature scale.
At calibration checks, the zero of the instrument had to agree with the mechanical pointer at open TC circuit, and could be adjusted.
Other suppliers used similar methods.
Obviously the TC extension wires had to be correct for the type of TC used, so that the cold junction was at the instrument.
