The QMX from QRP Labs is modified for operation from 40 to 10 meters. A perfect SOTA rig when matched to a 40 meter EFHW

After successfully using an End Fed Half Wave (EFHW) antenna for SOTA, I decided to build a 10 to 80 meter EFHW antenna for my home...

Two methods for transformer loss are evaluated. We learn that mismatch loss must be accounted for.

There are a number of factors in choosing a toroid for a RF transformer. While one may model electrical performance, calculate predicted...