The goal of attached schematic is to calculate NF of FET under different source impedance. Do do so, the different impedance is added as a small circuit that is port terminated and equation based output variable is created that represents needed ‘generalized NF ‘. The calculated value differs depending on where the equation is placed, in the Equation component or Diagram properties. The most likely reason is not accurate interpretation of expressions containing NFmin, namely 10^(NFmin/10) by Equation component. The expression in Diagram properties works fine. In the schematic file you can find comparison for debugging.