[Elecraft] 33.25ft vertical with KXAT1 - Why did it work?

[n3drk]

No reason for any forgiveness. We are all learners. I am awaiting an answer 
to this good post also.
john-n3drk


----- Original Message ----- 
From: "Martin Gillen" <martingillen at yahoo.co.uk>
To: <elecraft at mailman.qth.net>
Sent: Monday, September 12, 2005 12:27 PM
Subject: [Elecraft] 33.25ft vertical with KXAT1 - Why did it work?


> Hi.
>
> I was trying to build a field portable quick to
> install
> antenna and I really liked what I read about an end
> fed
> halfwave having a very low angle of radiation and only
>
> requiring a very short counterpoise however
> I remembered that the KXAT1 manual stated not to use
> lengths near a halfwave as they would be outside the
> matching range.
>
> So... I decided that I would cut an antenna to 33ft
> (20m halfwave), and then I would cut it back a foot at
> a time until the KXAT1 found a match.
>
> I started at 33.25ft vertical but I did leave a pair
> of
> 18.5ft counterpoise wires running at about 2 feet
> above the ground connected to the ground terminal.
>
> I tuned up and ... 1.2:1 match on 20m!
>
> I then proceeded to work KF6GC with 2W (almost 4000km)
> in the middle of a K Index = 8 solar storm!  So I know
> the antenna worked well.
>
> I modelled it in EZNEC and the impedance at the base
> of that antenna should have been 970 + j 1700 ohms,
> so I am surprised that the KXAT1 was able to match it.
>
> Any comments?  Was it because I left the counterpoises
> connected that it worked so well?  If I remove the
> counterpoises in the NEC model the impedance increases
> and becomes inductive to 1456 - j 1819 ohms.
>
> Comments?
>
> PS.  I am only learning in this stuff so forgive any
> overly simplistic analysis!!
>
> Thanks,
> Martin.
> VA3SIE.
>
>
>
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