Besides of eddy current losses there are also hysteresis losses in a TX core. Eddy currents are circulating currents within the magnetic laminations, caused by poorly aligned stacks of soft iron laminations. Also the surfaces may be rusted or rough and cause additional losses. Hysteresis losses are losses created by the positive and negative cycles of the 50 or 60 Hz sinewave. The quality of the iron (good BH curve) are the important factor here and heat is created in the back and forth going magnetic field. Copperlosses are directly proportional to the load on the TX (I