One of last year’s projects was the improvement of our Contest Station ED1R. For the various Yagis, we needed smart ways to combine antennas. Instead of buying commercial stackmatches (antenna combiners), I decided to build them up by myself and adjust them to our needs.

Continue reading

With his low cost, high precision Vector Network Analyzer, Tom (DG8SAQ) started a revolution in Ham Radio. Thanks to his efforts, amateur (and professional!) enthusiasts have now the possibility to perform measurements that were reserved to well-funded HF laboratories before. In this video, Tom explains the evolution and capabilities of his VNWA and why even NASA relies on it now as well! The presentation was held during the Ham Radio Hamfest in Friedrichshafen, Germany in June 2012.

Continue reading

During the summer break, it became quiet here on my blog. While Instead of chilling at the beach, I spend a lot of time on new Hardware and Software projects. Most of them are done, and now it’s time to document them. In this blog post, I want to share the construction of a versatile 4:1 Balun. In combination with a ladder line and an automatic Antenna tuner, you can use any dipole on almost all frequencies.

Continue reading

Over the last few years, I spent a lot of time simulating antennas. One annoyance I encountered over and over was the unavailability of values for ground conductivity and the relative permittivity. Two figures have quite an impact on the antenna performance, especially on vertical antennas. This finally led to the conclusion that both figures need to be measured. In early 2012 I built a measurement kit and finally determined ground conductivity and relative permittivity at our contest station.

Continue reading

Where ever I operate contest in a multi transceiver environment interferences between the 40m and 20m are guaranteed. An easy and inexpensive way to reduce interferences is to add coax stub filters. Dave, K1TTT has a great website with a lot of useful technical resources. One of them is dedicated to coax stub filters. After building up two sets of stub filters (one in Namibia at V55V and the other one in Spain at ED1R) it’s time to document it.

Continue reading

Author's picture

Tobias Wellnitz, DH1TW


Software Engineer

Germany