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As a hobby, amateur radio has long been encouraged to experiment with anything you might have on hand. When [Tom Essenpreis] wanted to use his 14 MHz antenna outside of his design frequency range, he knew he needed an impedance matching circuit. The most common type is the L-Match circuit, which uses variable capacitors and variable inductors to adjust the usable frequency range (resonance) of the antenna. Although inefficient in some specific configurations, they are good at bridging the gap between the 50 ohm impedance of the radio and the unknown impedance of the antenna.
Without a doubt, [Tom] was looking for parts in his trash can, using the ferrite rods, hot glue, magnet wire, copper tape and some extra 60 ml syringes from the AM radio to assemble the variable capacitors and inductors. Together. You can see him grind off the center of the plunger to make room for the ferrite rod. Wrap the outside of the syringe with electromagnetic wire, the arrangement of the ferrite can be adjusted by the plunger, and the characteristics of the components can be changed to adjust the circuit. [Tom] reported that he was able to use his newly made tuner for live streaming, and we are sure he likes to use his improvised equipment.
If you don’t like amateur radio, then maybe we can attract you with this syringe-based rocket, syringe-driven 3D printed drill press, or vacuum syringe-driven dragster. Do you have your own hacker to share? In any case, submit it to the prompt line!
I’m not a HAM and I don’t know much about HF, but I know that in some frequency bands, the TX power may be large, so the voltage on the antenna will be large. Could it be a good thing to install a non-conductive plastic tube filled with air between the antenna tuner and the control device?
He did mention some issues about inefficiency, which is not a problem. I remember in a book by Doug Demaw that he claimed that ferrites eventually behave like air at higher frequencies.
I used such a ferrite rod in the 80m fox transmitter (3.5MHz). Compared with the ferrite mixture of suitable frequency, the loss is in the range of 5 dB.
What is this mysterious American electromagnetic wire that I see on the Internet, and what does it have to do with magnets? Is it made of steel?
Magnet wire is a copper wire with a thin insulating enameled layer. I guess it is named this way because it is usually used to make electromagnetic coils, that is, for motor windings/speaker voice coils/solenoids/winding inductors/etc.
Or, if you don’t have a syringe, some corflute/coroplast material can be used as a coil former and the ferrite slips into it. For details, please see: https://www.youtube.com/watch?v=NyKu0qKVA1I
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