[Elecraft] Windom Project

Fri Jun 6 14:54:09 2003

Goto www.packetradio.com/windom.htm and look at his plans. The 4:1 balun
shouldn't cost me over $15 to build and won't be that heavy, and I will
probably support it anyway. I have ordered the AB-250 kit at
http://www.amidon-inductive.com/associates_prod_chokes.htm  as has Pete
WD6DKW. I hope to build the 10 - 160 mtr model.
Thanks

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Stuart Rohre
Sent: Friday, June 06, 2003 1:38 PM
To: Roy Vickers; [email protected]
Subject: Re: [Elecraft] Windom Project

Roy,
A technical detail.  While the "windom" you describe is not the classic
windom with single wire feed,  The use of a 4:1 balun is also a problem,
because in spite of the balun, since by definition one side of the antenna
is longer than the other, it will be unbalanced and I think you will have
some residual current on the outside of the coax shield.

A balun like this 4:1 is pretty heavy and costs a bit.   You might run
ladder line at lower cost, and just go to the balun at the shack tuner.
The length of ladder line will tend to re-achive the missing balance if long
enough.

Another solution might be to just use 95 ohm coax, and coil a bit at the
feed point to choke outside the shield currents.  It will be a closer match
to the antenna than the 50 ohm coax.  (As would 75 ohm).  Then, again use
your shack tuner to match the line plus antenna, at low cost.  TV coax is
often cast off by cable companies as new tag ends of residence drops on
reels.  Check with your cable person.

Another observation from the noted web site of antenna guru W4RNL, L. B.
Cebik.
The unbalance of an end fed half wave "Zepp" antenna to ladder line is only
about 10 per cent, and did not present impossible matching problems or RF in
the shack if the length is favorable.

Ideally, what someone needs to make is a true unbalanced "balun" that chokes
the shield current, but matches the impedance at feed point.  That would
likely involve a cored balun with unequal windings to make one side match
the shorter leg of the "windom".

It is an interesting antenna that works for some, but no better than a
dipole, just the feed point location may be easier access to the shack.  I
wonder if the balun has more leakage at some bands in the version on Buck's
web site?
GL and 73,
Stuart K5KVH

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