[Elecraft] {KX1} Antenna Matching Question

[Fred Jensen]

I no longer have my KX1 but it got a lot of use when I did.  I had the 
40/30/20 and KXAT1 options, the 30/80 hadn't been invented when I bought 
mine and life is too short for 2.5 watts on 80 anyway.  I made an 
end-fed wire out of 23 ft [7 m] of RG-58 by:

1.  Putting a male BNC on the end

2.  Stripping the outer black covering off to within 2 in [~5 cm] of the BNC

3.  Pulling the center conductor [still insulated] through the shield 
braid at the BNC.  This is easily done if you push the braid down to 
loosen it and then spread it, kink the center conductor, and push it 
through.

When pulled tight without the center conductor, the braid [counterpoise] 
will become somewhat longer than the center conductor ... maybe 5-10%.  
Wire goes into tree or telescoping mast, braid lays out on the ground.  
Tuned SWR on my 3 bands ran around 1.3:1, 20 was often 1:1.  The tuned 
SWR on 40 was a bit dependent on how I ran the counterpoise in relation 
to the antenna, but the effect was small.  I seemed to get better on-air 
results with the wire sloping from a tree or pole rather than nearly 
vertical, but that too was a small effect and probably subjective.  I 
kept this antenna rolled up on a camp clothesline reel in my KX1 bag.  
It went with the KX1 when I sold it.

I used a Buddipole for several years in places where I didn't have to 
carry it very far [heavy], but it was touchy to set up and my "recipes" 
that worked in the pasture at home never worked at my field sites so 
set-up took 30-45 min.  I finally switched to a mag loop [Alexloop] on a 
sprinkler tripod which works super with my K2.

2:1 isn't terrible considering that you don't have any transmission line 
loss.  Space limitations in the KX1 dictate that the KXAT1 can have only 
a limited number of L-C combos [64?], your match may be in between two 
of them.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/9/17 1:55 PM, stan levandowski wrote:
> When following the instruction in the KXAT1 manual and using a wire 
> between 24-28 feet and a 16' counterpoise for 40 and an 8' 
> counterpoise for 20, the best I can ever get is a 1.6 SWR on 20 and 
> 2.8 SWR on 40.
>
> I've spent lots of time shortening and lengthening wires and writing 
> down results and I can't hit the magic combination.
>
> The manual also makes it clear on page 8 that a 1:1 SWR is NOT 
> necessary for good performance.  I believe this because the little KX1 
> makes me plenty of contacts with this setup, including DX.
>
> I suppose I could just be happy....
>
> However, it bothers me that these SWRs are the best I can do. I don't 
> like seeing these high ratios on the display.   I built this KX1 but 
> had Don Wilhelm build and install the 30/80 module for me.  As part of 
> his service, he went over my KX1 and told me that it was up to spec.
>
> So my question is:  Has any KX1 user out there figured out a wire 
> length, length and number of counterpoises, etc. that gives a better 
> match with the KXAT1's capabilities??
>
> When I say I use a wire, I mean I throw it up into a tree and get it 
> as vertical and possible, then I lay out the counterpoise wires and it 
> all attaches directly to the KX1 with a dual binding post.  Just real 
> simple!
>
> Thanks for any words of advice and 73,
> Stan WB2LQF