I have a wire wound resistor that is changing too much when being heated and cooled. I know changing the chemical composition of the wire is the biggest factor in changing the temperature coefficient of resistance (TCR) of the wire, but I already have wires with a larger diameter of the same material. Although the resistivity of these wires would be lower, would the TCR improve? There would also be more wire on the resistor. I cannot find anything online that relates to this.
Changing the diameter of a wire does not effect the TCR of a wire. However the TCR is not necessarily linear. The TCR at a high temperature could be higher or lower than it is at room temperature. Of course a change in diameter will change the resistivity. Using a larger wire to make a resistor of the same value will mean that the temperature will not increase as much for a given power dissipation because there is more surface area available to transfer heat our of the wire.