PQ Cores Fair-Rite PQ Core configuration was developed for use in power applications. The large surface area to volume of the core aids in heat dissipation. PQ cores are employed both in filter and transformer designs for Switch Mode Power Supplies. Fair-Rite Products PQ Cores can be supplied with the center post gapped to mechanical specifications as well as an AL value. PQ Cores are available in a range of sizes from PQ20/16 to PQ50/50 and 3 materials with Initial Permeability ranging from 2300 to 3000.