EFHW Build - High SWR on 15, 12 & 10

[WB2PHL]

Here is a link to this topic from a few years ago

Understanding and building my first EFHW

I put up my 6m mast out in the garden and plugged the antenna, and this is what I get with 3 / 22 ratio (I got +/- the same with 3 / 21) [3_22_ANT] A good SWR on 14.250 but the 10m band … Not only SWR is bad but the resonant frequency is 29.5 MHz (as predicted by mmana gal simulation). Edit : Same results on the radio itself, a very satisfying 1.0 (!) SWR on 14.2MHz but 2.6 SWR on 28.2 MHz.

Also Youtuber MM0opx has videos on testing various transformer cores efficiency. You may wish to look into that. 73 es GL