Article by N5ESE Here’s yet another handy little Altoids QRP project. This makes a great travel companion to the 1:1 current balun and is intended to aid in tuning a balanced antenna or feedline that has a high impedance (100-600 ohms). I’ve even used it successfully to tune a 20 meter, 1/2-wave vertical with 4
Article by N5ESE Here’s another handy little Altoids QRP project. For Field Day 2002, I wanted to use my new Elecraft K1 (which has an automatic antenna tuner built-in) to feed a full-wave loop on 40 meters, to use on all bands 40 – 15. To preserve the feedline balance (I used 300-ohm ladder line),
This balun documented by I0QM use a ¼ wavelength and the ¾ wavelength adapting sections with the 50-Ohm coaxial cable, or a coax line with the impedance you need.
A homebrew 9:1 Balun experience
The following diagrams and tables show some simple 1:1 and 4:1 baluns for use between 1.8 and 30 MHz using twin transmission lines made from enamelled copper wire (ecw). The bifilar windings have been adjusted (spacing) to produce transmission lines with Zo of 50 or 75 ohms as required for best matching. These designs should
Article by Charles Greene, W1CG My 4:1 current-type balun is wound on a FT-114-43 core. The FT-140-43 is a little easier to work with, and maybe the FT-140-77 would cover 160-10. This one is reasonably flat from 4.5 to 35 MHz but drops off a little at 3.5, 40-ohms with a 200 ohm resistor on