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17 meters was very high and beyond the capture range of my automatic antenna tuner. I suspected that it had to do with the linear loading used by the C3SS so I created EZNEC models for the C3SS and C3S for comparison. As expected, the EZNEC simulations confirmed the high SWR of the C3SS ( >50:1 ) on 17 meters compared to <10:1 with the C3S. The C3S is able to function on 17 meters because the full length elements on 20 and 15 compensate each other and average out close to 17 meters. The linear loading of the C3SS behaves like a trap on 17 meters disrupting the compensation. Assuming the C3SS loading wires behave like traps at high frequency, I noticed that the 20 meter element segments closest to the boom should resonate near 6 meters. EZNEC predicted a very low SWR ( <2:1 ) at 51.5 MHz and this was confirmed by actual measurements on my C3SS. The 6 meter performance is surprising good with a maximum gain near 10 dBi at 50 MHz. I was thinking about converting my C3SS to a C3S but the C3SS is so good on 6 meters that I will keep it. I have confirmed the 6 meter performance in practice and verified the excellent gain and F/B, F/S ratios. How's that for serendipity? -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 Submissions: send to Force12Talk@qth.com To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk For problems with the list, contact n4zr@qth.com |
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