I recently bought two Diamond MX-2000N triplexors because at my current place I only have one space for one RF cable from the shack to the roof. The idea was to have one triplexor in the shack and another one below the antennas. Before installing the triplexors I decided to bring them on the bench and check if the claimed performance is met by the devices.

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A few years ago I migrated almost entirely to OSX & Ubuntu. However I still had to maintain a Windows copy on one of my harddrive partitions, since a few applications were just available for Windows. In particular, DG8SAQ’s superb Vector Network Analyzer (VNWA) software. I can already use most of the applications in a Virtual machine, with the benefit of not having to reboot and change the OS, but DG8SAQ’s software with it’s USB I/O always gave me hard time. Finally I figured out what need’s to be changed. Now the VNWA runs also smoothly in a Virtual Machine.

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This question bugged me after trying to exchange the connectors of a 25m long Aircell7 coax cable. During preparation I discovered a black inner conductor. I seems water entered the cable. Do I have to throw it away? Read more to discover a probably unexpected answer!

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One of last years 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 buy myself and adjust them to our needs.

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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 which 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.

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Over the last years I spent a lot of time simulating antennas. One annoyance I encountered over and over was the unavailablity of values for ground conductivity and the relative permittivity. Two figures which 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.

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Author's picture

Tobias Wellnitz, DH1TW


Software Engineer

Germany