This is a long page containing 4 tables. The first two relate to magnetic properties. The second two relate to dimensions. These formulas work if you have a table to use them with such as the example table below for 100 turns. Phenolic is nearly an air core.
Color codes hold only for cores manufactured by Micrometals.
Courtesy of Amidon Association and Micrometals. 5000 Max perm. Coercive force Oer 2.40 1.60 0.30 0.22 0.16 Temp. Please contact the WebMaster .