|The 9 to 1 unun is at the bottom. The box at the top is a LNR end fed matchbox.|
The unun I use is from Balun Designs. There is a chart on their site that shows SWRs and various lengths. I don't seem to get SWRs shown but by pressing tune on the KX3 I will get a match. I actually have used the 9 to 1 without a counterpoise and have gotten great reports. However, I do find that it the SWR is more stable and lower if I use a counterpoise. You can get a feel for this by touching the ground terminal on the unun and seeing how the SWR changes on an analyser. I don't think what the wire length or counterpoise is is that critical. I adopted 100 foot as that is how my roll of ribbon cable came. I did go back to the manual and it seems that four 30 foot wires for a counterpoise fits their recommendation.
|counterpoise wires spread out.|
wind it up in the same way.
|Ribbon cable for radiator on left and counterpoise on the right.|
Here is the data from a little study I did. SWRs on the right are with my hand touching the ground to see the change in SWR. I take it that if my hand touching makes little difference I have an better ground. The value to the left of the slash is SWR and to the right was the R value on of my Ten Tech FG-01 SWR analyser.
As far as the supports I have been using a Jackite 31 foot pole near the rig and a 20 foot pole at the far end. There are details about those poles at this link.
I get great results on 40 meters with the 100 foot length of radiator. That is usually why I go with this configuration is to cover my 40 meter contacts. It does work OK on other bands as well.