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?

cable_guy

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

dhdl_icon

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

toolbox

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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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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A simple broadband 4:1 Balun Transformer

During the summer break it became quite 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 blogpost I want to share the construction of a versatile 4:1 Balun. In combination with ladder line and an automatic Antenna tuner you can use any dipol on almost all frequencies.

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How to measure Ground Conductivity

Picture of a Measuring tape

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 ED1R .

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