Amazon.com: Balun One Nine v2 - Small Low-Cost 9:1 (1:9) Balun with Input Protection & Enclosure for HF & Shortwave. Great for Software Defined Radio (RTL-SDR & SDRPlay), Ham It Up, and
Antenna 9:1 impedance transformer for the RTL-SDR to connect long wire 100k - 50Mhz (BALUN)
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