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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Recently my Yaesu FT857 became deaf. It turned out that the plastic enclosure of the FT857 filters over time consensated moisture which ruined the filters. In this post I’ll show you how I replaced the filters and brought the radio back to life.

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At our contest station ED1R we have no space for permanent Lowband Verticals. Each Contest, the verticals have to be installed temporarily in a field nearly. Especially the deployment and removal of the antenna radials is very time consuming. Over time we optimized our system which reduced the required time from 2 hours down to 30 minutes.

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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