My most successful End Fed Random Wire is a radiating wire 58 feet long or 17.678 metres long with one radial 13 feet or 4 metres long.
I use a 6m long telescoping pole as support and antenna is an inverted L config.
The reason I arrived at these wire lengths was mostly influence by the tuner in my KX3 or the MT1 LC manual tuner I use with my FT817. Both tuners seem to tune this combo the easiest on all bands from 40m to 10m. It also radiates very well for a none resonate antenna with QRP. I have chased many SOTA activators from my back yard around VK ZL and JA. Had a S2S qso on 20m one time with EA2CW on 20m CW using this antenna on afternoon greyline for me.
The antenna is set up with 5 metres of the wire vertical up the pole the remaining wire is horizontal across the yard to another support. I have a plastic home made winder to insulate between the two wire with a short length running to the tuner or kx3 binding post on the antenna socket of the rig. If the “feed” junction is about half a metre off the ground the radial is run out under the antenna in the same direction as the antenna. I find a short stick and tie the ground radial to it and poke it in the ground, the radial is insulated from the earth. I saw a DL station do it this way on YT he liked to have an angle of 135 degrees between the vertical part of the L and the ground radial sloping down to the tie off stick a few inches long. My LC tuner has several selections of inductance and I like to tune with a more centered capacitor so its not jammed fully one way or the other and as for the KX3 well the excellent tuner does its own thing for me. My FT817 loves this combo and as you will know if the rigs not happy it won’t give full power. Done a few WSPR tests with it as well and been heard in a few dx countries and locally in VK on a few bands. I am no Techno Weeni on the theory of it all just a practical person with the above results to show. There also have been some famous U.S. QRP CW SOTA ops using a 58 foot antenna of varying incarnations for several years its where I got the idea from working them from my home station.
Regards
Ian vk5cz …