Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk> With regard to the Transformerless TC is it OK to specify a value of Av and use formula L2 = L1*Av^2-L1 to determine appropriate value of L2 for ANY value of L1?