[Elecraft] KX1: requesting recommended wire antenna lengths advice

[Michael Babineau]

Pat / Jim  : 

The idea is that there is no coax feed line.  I suggest that you connect the wires directly to the rig / ATU and forget about the unun and coax.
Because a 24/28 foot wire is non-resonant if you use coax to feed it you will incur additional loses because of the mismatch.  No feed-line means no feed line losses. 

Michael VE3WMB 

P.S. Pat if you want a longer length wire,  try 51 feet. It will load very well on 40m/20m, but it may require that you roll up a couple of feet to get below 
2:1 SWR on 30m.  I sometimes use this as an end-fed inverted vee or inverted-L worked against the previously mentioned ribbon cable ground.  The KX1 ATU will
match this.

P.P.S. As a compromise I tried a 26 ft wire at one time and I was able to get a reasonable match on 40m, however I discovered that it is much more sensitive to how it
is deployed, as compared to the 28 foot wire and in some configurations it was hard to get a decent match. 

On Apr 20, 2015, at 3:00 PM, jim <jbollit at outlook.com> wrote:

> The length of you coax feed line also needs to be considered.
> 
> The feed line is a "transformer" by itself.
> 
> Jim
> W6AIM
> 
> 
> 
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Pat Ring
> Sent: Monday, April 20, 2015 10:51 AM
> To: Michael Babineau
> Cc: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] KX1: requesting recommended wire antenna lengths advice
> 
> Thanks for all of the list and offline posts.  All very helpful.  I thought the 24' length was going to be quite a compromise.  Tried 28' but that didn't help much.  Will try the solutions suggested.  Michael, I was reading one of your blog posts describing your folded dipole and grounding solutions and dismissed it initially because I didn't want to carry a pole.  Now I have a thought in mind on how to deploy without a squid or jackite pole and will look into that when I get back (I have some cat 5 cable I will untwist).  Reluctantly packed some coax, unun, and long wire
> (KX3 Helper) for the trip, but will look into other solutions when I return.  I know this radio has been out for years, so I knew there would be a bunch of expertise here to help me.  Thanks.  Pat NQ0N
> 
> On Mon, Apr 20, 2015 at 8:05 AM, Michael Babineau <mbabineau at magma.ca>
> wrote:
> 
>> 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.
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