I happened to stumble across some antenna projects showing common mode chokes 1:1 baluns made of some turns of coax wound on T200-2 iron powder toroids. Will they work? The role of a choke A choke BALUN works by letting through the differential current and by hindering the common mode one by opposing some impedance. The key […]

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In my experience with computer antenna simulators (I mostly use 4NEC2), I had the feeling that those tools, if correctly employed, can be quite accurate. Unfortunately, when working on shortwave antennas, the interactions with the surrounding environment make the results a bit approximate: such long wavelengths make impossible, at least for us hobbyists, to avoid the environment to […]

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that is the question, for many ham radio operators. A simple, resonant, single band, plain-vanilla horizontal dipole, does really need a 1:1 balun… or not? To investigate the differences between a dipole having a 1:1 balun and another one directly connected to the coaxial cable, I build a 40m band dipole with a remotely controlled switch […]

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One of the most tempting all-band cheap antenna solution when a lot of space is available is the “long wire”. The idea is to lay a wire as long as possible and to feed it at one of its ends, while the other pole is grounded. Some kind of fixed impedance transformer plus maybe a tuner […]

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In the world of HAM radio, there are several myths that survive through generations despite them clashing with laws of physics. However it is quite interesting to see how easy is to debunk some of them with very simple experiments. The radiating line myth In HAM radio discussions “experts” frequently advise against antennae tuned by a tuner […]

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[Also available in English] – Praticamente tutti i principali produttori di ricetrasmittenti, sia radioamatoriali che civili, hanno in catalogo modelli UHF 400-470 MHz dotati di serie di connettore SO-239, cioè la femmina del vetusto “PL”. In molti casi, forniscono connettori diversi in base al mercato: N in Europa, PL nel resto del mondo. Ad esempio, l’Icom […]

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[PL-259 vs. N on 430 MHz follow-up] – Many OM assert that they can not withstand the performance penalty introduced in the 430 MHz band by a SO-239/PL-259 pair. Curiously, all the major rig makers seem to ignore this fact. For example the Icom IC2820, the IC7000 and the newer IC7100, the Yaesu FT857/FT897, Alinco DR635, Yaesu FTM-400 and the new Yaesu FT991, among […]

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Scosse dal microfono, router ADSL che si resettano, casse del PC che impazziscono, apparecchi che si spengono e riaccendono da soli come fossero posseduti dal diavolo. I forum, i social network e le nostre sezioni sono piene di amici esperti pronti a prodigarsi in consigli: profusioni di ferriti, choke, messe a terra, strani fili che dovrebbero […]

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