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 at V55V and the other one in Spain at ED1R) it’s time to document it.

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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.

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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.

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Tobias Wellnitz, DH1TW


Software Engineer

Germany