Interesting. My SWAG was the obvious transmission line/feed point impedance mismatch, but I would have never thought about the fasteners being the issue. I'll be reading up on eddy currents now and how they apply to impedance. Is it possible that it's not actually the ferrous materials and the eddy currents generated, but the mating of dissimilar metal conductors separated by a thin layer of aluminum or other oxide setting up some level of capacitance, and/or some additional inductance added by the stainless fastener and feed-line attachment (a 1-turn inductor?)?
All that put together in some freak fashion would lead me to believe a small L-C network was created that may have caused a transmission line to antenna impedance mismatch uncorrectable at the station... indeed, under-reported in the SWR readings. Just a huge guess and just curious. Adding this to my "file drawer" of troubleshooting ideas, but I'd like to understand the science. Of course, it could be simpler... simply multiple interfaces of sufficiently incompatible metals that it sets up galvanic corrosion in multiple layers. > ...The trouble was at the connection of the feedline to the antenna. > (...) I think that it was due to the ferrous material (stainless > steel) of the bolts heating due to eddy currents in the strong RF field. > > I will change the method of connecting the line on Sunday and I hope > it will solve the problem. Assuming the root cause is galvanic corrosion (and potential introduction of capacitance and/or inductance), I would surmise the solution to be setting up a connection where no two incompatible metals are touching. Something like a bi-metal connector kinda like the one on this page (only correctly sized): http://www.utilex.com/bi-metallic_connector.htm If I'm way, way off base, please educate me. I'm on this list to learn. 73, ______________________ Clay Autery (testing 02/20/16) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
