Portable HF has always been fun, recently I have joined the End Fed Half Wave club. I purchased a few EFHW 49:1 or 64:1 matching transformers and wanted to try these out at a recent LEFARS field weekend.
Typically an EFHW will operate on multiple bands, so 20m of wire will provide a resonant antenna on 7, 14, 21 and 28 MHz. The principle if an EFHW will present around 2500 to 3,000 Ohms to the radio, and a matching transformed would need to provide something more like 50 to 60 Ohms to the radio.
You could make one quite easily, but you can also purchase one from as little as £17 to £22. If you consider time, materials and boxing it hardly seems worth the effort!
Lightweight coax is also helpful when portable, and RG316 could be just the answer. You can order this with BNC ideal for the FT 705 or 817
It’s also worth remembering they will be high voltage, and subject to detuning if they are close to obstructions. Keep everything clear, including people and pets!
The antenna needed a trim and then presented a good match on 7 and 14 MHz. I could use 21 MHz, but the tune point was a little higher than the FT8 section in that band.
The internal ATU was used on 21 MHz to extend the range down to the lower part of the band, it’s possible adding a few more centimetres onto the antenna would fix this.
The QSO count for the weekend was around 130, mostly on 21 MHz. The QSO map shows good propagation mostly in the early evenings/mornings with several QSO into JA and USA