Surplus syringes make a satisfactory tuner for amateur radio experimentation



Amateur radio as a hobby has long encouraged experimentation using whatever one can have on hand. When [Tom Essenpreis] wanted to use his 14 MHz antenna outside of his designed frequency range, he knew he would need an impedance matching circuit. The most common type is an L-Match circuit that uses a variable capacitor and a variable inductor to adjust the usable frequency range (resonance) of an antenna. While ineffective in some specific setups, they excel at bridging the gap between the 50 ohm impedance of a radio and the unknown impedance of an antenna.

Probably looting his junk box for parts, [Tom] hacked together a variable capacitor and inductor using ferrite rods from AM radios, hot glue, magnetic wire, copper tape and extra 60ml syringes. You can see that he ground the center of the piston to make room for the ferrite rods. Wrapping the outside of the syringe with a magnetic wire, the alignment of the ferrite can be adjusted via the plunger, changing the characteristics of the element to tune the circuit. [Tom] reports that he was able to make on-air contact using his newly made tuner, and we’re sure he enjoyed putting his makeshift gear to use.

If amateur radio isn’t your thing then maybe we can woo you with this syringe based rocket, syringe operated 3D printed drill press or vacuum syringe powered dragster. Do you have your own hack to share? By all means, submit it to the Tip Line!

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