This last weekend I decided to roll my own 9:1 Unun for use with my Elecraft KX3 and whatever piece of wire I happen to have handy. This project is really simple and most of it was made using stuff I found in my junk drawer. There are plenty of end fed wire antennas commercially available for around $75, but you can build the core of this antenna for less than $10. Here's my version. Parts: Here's the complete parts photo for the 9:1 Unun. I used 3 different colors of wire (to make it easy to keep track of each wire), a random iron core toroid (it looks like it might be T-200-2 core), a small project box, chassis mount BNC and binding posts The first step is to figure out a way to manage carefully wiring 3 lengths of wire around the coil. My solution was simply to use some scotch tape every couple of inches to organize the cable. The scotch tape will disintegrate over time, but that's OK - the only purpose is to help you wind the wire around the core. Wind 9 turns around the core with the three wires. I used a couple of small zip ties on either end of the windings to hold everything in place. Now, solder up the wires as follows: Red wire on left side of unun winding and green wire on right side of winding goes to BNC "hot". Blue wire on left side of unun winding is soldered to red wire on right side of winding. I used a little liquid electrical tape to cover the connection after soldering Blue wire on right side of unun winding goes to "hot" antenna wire terminal Green wire on left side of unun winding goes to bnc ground. Optional: if you add a ground terminal for a counterpoise wire, jumper the bnc ground to the ground lug. The antenna will perform better if you can lay out a ground wire; otherwise it will use the coax shield and radio chassis for ground. That's it! I used a little hot glue to help keep the thing from rattling around. Testing the 9:1 Unun If you have an analyzer or any type of SWR meter, it's fairly simple to test your work. I twisted together 3 150 ohm resistors to create a pure resistive 450 ohm load (50 ohms x 9) and hooked it up across the wire terminals. A basic 470 ohm resistor will be close enough, as well. Here's a pic of my analyzer showing an SWR sweep: On 80 meters, the 9:1 unun shows about a 3:1 SWR, on 40 meters, it's right at 2:1 SWR, and it flattens out at 20 meters and stays under 2:1 SWR through most of 10 meters. Of course, results will vary depending on the actual load, but with a decent tuner, you'll be able to have fun with this simple impedance transformer with all kinds of random wire antennas. I'm only going to run about 10-15 watts through this unun, but if you used a little thicker wire, you could certainly run 100 watts with a core of this size. This whole project took less than an hour and most of that time was spent organizing the wire itself. Have fun!