[TowerTalk] Partial KT34A??

Michael Tope Michael Tope <w4ef@pacbell.net>
Thu, 20 Jul 2000 18:40:35 -0700


Mike,

The following are the measured standalone resonant
frequencies of the KT34XA rear and front driven
elements. I got these numbers from Mike Stahl, K6MYC
who pulled them from one of his old KLM design
notebooks. These numbers represent the resonant
frequency of the elements when they are set at factory
specified dimensions and measured by themselves on
a tower (40' above ground I think). I did my own
measurements recently, but I don't trust them as
much as I wasn't able to get the elements far enough
away from a roof gutters and other ground clutter to
get decent readings.

Here are MYC's numbers

Rear Driven
28.750
20.925
14.030

Front Driven
29.400
21.860
15.075

For what its worth, before installing them on the KT-34XA
boom, I ran 1.4 KW key down into each one of our club's
KT34XA elements using a 1:1 balun. I saw no signs of heating.
To feed one of the driven elements, don't use the T-match, as
the impedance of the standalone element is reasonably close
to 50 ohms at resonance. I connected the balun directly
to the screw terminals on adjacent the centerline of
the lexan center insulator (the terminals where 4:1 balun
and crossed parallel transmission line normally connect).

This should make a good rotary dipole.

Good Luck

Mike, W4EF....................


----- Original Message -----
From: <WA5JWU@aol.com>
To: <towertalk@contesting.com>
Sent: Thursday, July 20, 2000 12:11 PM
Subject: [TowerTalk] Partial KT34A??


>
> Hello All,
> I have an old KT34A that I am in the process of rebuilding.  Time
commitments
> will not allow me to finish the project and raise an additional tower
before
> the NAQP in August.  My second radio, however, still needs an antenna.
Does
> anyone know or have an opinion on whether I can use ONLY the driven
element
> (one of them) as a rotatable dipole just for the contest.  I think the 4:1
> balun should not be affected by only one element being used or is that
second
> driven element part of that equation?  If I use just one of the driven
> elements as a rotatable dipole, should it be fed a different way than the
52
> ohm coax and 4:1 balun?
>
> Any thoughts or opinions on these questions would be greatly appreciated.
>
> Thanks and 73,
> Mike, WA5JWU
>
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