EA4EOZ, an amateur radio electronic enthusiast: Build your own HF balun
1:1 Voltage Balun for HF wire dipoles – M0UKD – Amateur Radio Blog
How to make a 4 to 1 balun cheap and easy - YouTube
How to Make a Balun or Unun : 3 Steps - Instructables
Amazon.com: Balun One Nine v1 - Tiny Low-Cost 1:9 HF Antenna Balun and Unun with Antenna Input Protection for Ham It Up, RTL-SDR, HackRF and Other HF-Capable Radios. Great for DIY Dipole