Nordholt antenna uncovered

After functioning 30 years on the roof, the Active nordholt antennas used for the WebSDR receiver failed. One failed during repositioning of the supporting masts, and one did shortly after. If the large RADAR next to the antennas former place acted as lightning “rod” for all these years remains unknown. I opened up the antennas for closer inspection to find one damaged capacitor, looking like it suffered from severe over voltage (lightning?) and no visual defects on the other antenna.

However, this was not the most important finding! After some reverse engineering I found out that both antennas which worked fine for many years are NOT exactly what articles from Ernst Nordholt described. Interestingly enough, there are at least two more transistors, and only one rare FET instead of two!

More info will follow on my Nordholt antenna page!

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