Yesterday I received the Nooelec "Balun One Nine V2" and did limited testing. It uses a Coilcraft WB9-1 transformer, with a published 3dB bandwidth of .125-125MHz; interpolating the datasheet graph shows about .5-70MHz at the 1dB points.
I put it on the nano and set span 1-30MHz and calibrated OSL with 450 Ohms as the load.
Then attached 900 ohms and got SWR 2.0; attached 4500 ohms and got SWR 10.0.
I have not yet tested it with reactive loads.
Certainly not a lab-grade test accessory, but may be useful for characterizing parallel transmission lines and high-impedance HF antennas.
--KV5R
