Sotabeams Switched Inductor

This is an interesting little kit and not much information on the net about its use so I thought that I would add a quick blog entry about what I discovered about it. I am building an L match and started with the inductor. I really had no idea on windings, so i started with 6 turns and added 2 turns per inductor, with the 7th inductor having 18 turns on it. I spent about 20mins working out the switch, it is meant to be a 6 position switch, which in reality is a 10 position switch with a limiter. However in my case, it looks like i was given a 5 position 2 pole switch. While mildly annoying, with 5 positions I get 270nH -> 3.7uH inductance, and if i switch from the low side input to the high side input gives 1.7 -> 5.5uH, while adding switching is a pain in the arse, it is not the end of the world to have one inductor not in the loop. If i had realised before soldering in the switch i would have used a 10 position switch i have here and made it work right from the beginning. It is what it is, no use worrying about it now. 3.7uh is more than enough inductance for any antenna i build.



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