Measurements

Tobias (DH1TW)

2 minute read

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…

Tobias (DH1TW)

2 minute read

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.

Tobias (DH1TW)

1 minute read

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!

Tobias (DH1TW)

5 minute read

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.

Tobias (DH1TW)

3 minute read

Where ever I operate contest in a multi transceiver environment interferences between the 40m and 20m are guaranteed. An easy way to reduce interferences are 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 – V55V and the other one in Spain at ED1R) it’s time to document it.

Tobias (DH1TW)

2 minute read

In preparation of the upcoming CQWW 160m Contests my friend Hannes, DK1NO was so kind to give me one of his W7IUV broadband, high IP3 preamplifier. Thanks, Hannes! Without knowing the exact performance data, I ran a few measurements with my Network Analyzer on the amplifier to determine the Gain and it’s operational fitness. Read on for measurement results and additional notes on how to measure active components.

Tobias (DH1TW)

8 minute read

It finally happend…. After a decade of reliable service, my Alpha91b amplifier broke. Most likely on it’s way to Spain one of the tubes broke. During the comissioning at ED1R contest station, fire & smoke shot out of a chimney. The first shock was big, but a few measurements confirmed that just the tubes were broken. In this blog post I will share the knowledge I gained during during debugging, comissioning and breathing new life into the amplifier.

Tobias (DH1TW)

5 minute read

This year we wanted to seriously compete in CQWW CW from ED1R contest station. While the station is equipped reasonably on all bands with Yagis and verticals, there were no dedicated receiving antennas available – yet. Out of my former contest participations from other stations I know that when it come down to winning a CQWW, dedicated receiving antennas are a must have. Beverages provide great directivity and reduce the EU clutter significantly.