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

In an earlier post I described the modifications I made to the KD1JV designed TriBander to make it more useful for SOTA. The...

This post outlines the modifications made to reduce receive current consumption, reduce weight and size, and change the controls and readout

The high voltage supply for the vacuum tube transmitter needs to be low noise in the 40 meter band, efficient for battery operation and...

A Modified QCX and TR Switch for Vacuum Tube SOTA transmitter

A single tube transmitter is developed for portable and Summits on the Air (SOTA) use. The SOTA transmitter had to be relatively...

Using vacuum tube equipment for SOTA activations? Why not! A portable battery operated vacuum tube transmitter is part of a SOTA system.

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.

Exploration of using the nanoVNA to measure inductance and capacitance at frequency of use.

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

Pole Mountain From My Operating Position Summit Trip Summary Distance: ~ 2.6 mi one way Transport: Hiking Elevation Gain: ~500 feet...

Like many radio amateurs I was initially intimidated by the Smith chart. Transmission line and antenna theory, unfamiliar terms and...