I got a LNR Precision EFT-10/20/40 Trail-Friendly multibander, and spent a while trying to tune it today. The manual recommends tuning on the 40m band, so I trimmed until I got the minimum SWR (1.2 – quite good!) right around 7.2125 MHz – the center of the US 40m phone allocation.
The manual says that once you’ve tuned for ideal SWR on 40m, 20m and 10m resonance should also fall into place. But my tuner shows that the minimum SWR is still about 800 KHz too low on 20m, and several MHz too low on 10m. I had the antenna set up as a sloper, with the top a little under 20’ in the air, and the bottom attached via bungee cord to a normal tent stake.
Has anyone else had this issue?