[Elecraft] KX1: requesting recommended wire antenna lengths advice

[Michael Babineau]

Pat wrote : 

>The 24' wire tuned up fine on 20m and 30m, around 1.2:1, but I can't get an KX1ATU lower than about 8.9
>SWR on 40.  Am I missing something obvious, or should I continue to
>experiment?

Pat : 

My experience is that you need a wire longer than 24 feet to get a decent match with the KXAT1 on 40m.  
Anything over about 12 feet long should match pretty well on 30m and 20m. Try 28 feet if you want to 
include 40m and perhaps consider a more extensive ground. 

For a ground system I use a 20 foot length of computer ribbon cable with 5 or 6 conductors. 
Unzip all but about the last 3 or 4 feet and then tape it so that it doesn’t unzip further. Strip all of the conductors at the 
intact end of the cable and attach them all to a banana plug.  This makes routing the ground off a picnic table easy as it is 
one big flat ribbon but the individual unzipped wires can then be splayed out in different directions on the ground.  
I find that with more than about 5 or 6 conductors it starts to turn into a bit of a tangled mess. 
If I decide I want more radials then I use two of these. Note that the Pomona BNC to banana jack adaptors will allow 
two banana plugs to be connected to each terminal (i.e. 2 on the red and 2 on the black). 

If you want to use a shorter wire that will fit on a 20 foot fishing pole then try a 20 ft length of twin lead (I use the lightweight
Radio Shack Indoor twinlead) with the leads at the top shorted together and soldered. Install  banana plugs on both of the 
leads at the bottom.  For 20m and 30m you can connect both banana plugs to the centre of the KX1 BNC, giving you 
a FAT 20 ft radiator. On 40m just disconnect one of the banana plugs and now you have a 40 foot radiator that is 
folded in half … which is effectively a 20 foot linear loaded wire that will resonate a bit below the 40m band, but will
match quite nicely on 40m.  (Think of it as half of a 40 foot long folded doublet/dipole).  

I have used this configuration with a 20 foot fiberglass pole to make hundreds of 40m KX1 qsos and it works quite well and deploys quickly. 


Michael VE3WMB 

P.S. Trust me .. folding the wire back on itself does not result in signal cancellation. At worst your vertical will have a very slightly 
asymmetric omnidirectional radiation pattern.