[Elecraft] KX1: requesting recommended wire antenna lengths advice

[jim]

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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