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

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...

Electrostatic Discharge (ESD) is a subject that can inspire a lot of discussion, head shaking and some misunderstanding. ESD damaging...

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

This blog outlines the steps taken to determine why a microcontroller no longer works, and the journey to find the damage on the chip.

This is a light system that I designed and built in 1978 to control large flood lights of different colors, synchronized to disco music...

Being the holiday season I decided to post this article from the December 2014 issue of Nuts & Volts magazine www.nutsvolts.com that I...

A prior post described the development and build of a clock to display time and date for UTC and Local. The clock characters are large,...

The Raspberry Pi (Rpi) is a great single board computer (SBC) that can be used in many projects and comes in different configurations. I...

Recently the Maker Space that I frequent received a number of 4 line 40 character (4 x 40) LCD displays. They asked me to figure out how...