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DXHeat Logo App Rounded

Over last 8 month I was digging deep into Web Development. The result went yesterday public – Instead of building just “another” Web DX Cluster, I tried to build something innovative with new, unique features. Best is to check it out by yourself!

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Will additional coax stubs improve Bandpass Filter performance?

4O3A 20m Filter with coax Stub

I was curious if the performance of our 4O3A high power Bandpass filters could be improved with additional coax stubs in parallel. We were operating at ED1R for some time now with the added stubs, and we are pleased with the results. Check out the details!

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How to rapidly deploy & remove antenna radials

Thumb Up! Antenna radial improvement

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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Can I still use oxidized coax cable?


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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4O3A Triplexor

Dummy Load

Until today, I’m fascinated what can be achieved with good filters. At our Contest Station ED1R we bought a Triplexor (10m/15m/20m) in order to be able to use our new Optibeam OB11-3 on the three bands simultaneously.

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Double Half Delta Loop (DHDL) Low Band Receiving Antenna


A few days ago I had the time to build and try a Double Half Delta Loop (DHDL) at our Contest Station ED1R. The Antenna was built within 3 hours and can be deployed / errected within 20 minutes.

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Microcontroller based Stackmatch Controller

Stackmatch Controller Thumbnail

At our Contest Station ED1R we have on each highband 3 Yagis available. In 2012 I built 4 high power Stackmatches in order to switch and combine them properly. Since I never liked the way of WX0B’s stackmatch controllers with the rotative knob, a microcontroller and button based solution was the answer. After a few contests the solution has proven it’s reliability and comfort.

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New Stackmatches for ED1R


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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SDR – where are we today?

Woman looking through a mangifying glas

At the second HamRadioWeb convention in Bolognia, Italy Claudio, I4LEC has given a great presentation about the current status of SDR. In his presentation he starts with SDR principals then analyzes then the strength and weaknesses of available Software Defined Radios (mainly FlexRadio Products) and finishes with a comparison against TS-590 and Elecraft K3. The presentation is entertaining and informative at the same time. Definitely worth having a look at!

Claudio was so generous the grant the permission to show it on my website!

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Evolution of the DG8SAQ VNWA

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!

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