[Antennas] Gain with wire ...

Tue, 2 Apr 2002 18:06:03 -0600

Thanks George.
So why all the hoopla about baluns on things like G5RV and other multiband
wires?? I ran a G5RV for a couple of years and I was always asked why I
didn't have a BalUn on it .... my answer was that I did not build one and
that LB Cebik, W4RNL said it wasn't necessary.
----- Original Message -----
From: "George, W5YR" <[email protected]>
To: "Tim Billingsley" <[email protected]>
Cc: <[email protected]>
Sent: Tuesday, April 02, 2002 4:18 PM
Subject: Re: [Antennas] Gain with wire ...
> Tim, use a 1:1 current (choke) balun and let a tuner worry about the
> impedance transformation. All you want the balun to do is to minimize
> common-mode current on the coax braid. The impedance seen at the input of
> your feedline is going to vary all over the lot with different bands so
> there is little to be gained by attempting to somehow "transform" 450-ohm
> ladder line to 50 ohm coax with a 9:1 balun. It would work, but only on
the
> band and/or frequency where the input Z of the ladderline was (a) 450 ohms
> and (b) resistive.
> These conditions can almost be guaranteed to never be present
> simultaneously and it takes both for the balun to "work" as designed. It
is
> a far better solution to separate the tasks of impedance transformation
and
> balanced load feed from unbalanced line. Do the first with a tuner and the
> second with the most effective balun that is relatively insensitive to
> impedance and SWR levels: the current or choke balun.
>> I use three such antenna configurations here, two 20-meter EDZs and one
> 40-meter horizontal loop, and each ladderline goes through a W2DU bead
> balun to coax then to the tuners in the shack. There will be high SWR on
> the coax on some bands, but if the length is kept reasonably short, the
> losses are negligible. I can tune my EDZs on 80-10 with the MFJ 989C tuner
> with no problems, no critical line lengths, etc.
>> You can buy W2DU bead balun kits or finished units at The Wireman - see
any
> QST for their ad. If you intend to be running max power - whatever than
> means these days - then you will want to use ferrite core baluns wound
with
> parallel line or coax. See the Handbooks for info.
>> No rhetoric - just advice based upon sound practice and application.
>> 73/72/oo, George W5YR - the Yellow Rose of Texas
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> Amateur Radio W5YR, in the 56th year and it just keeps getting better!
> QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
> Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
>> All outgoing email virus-checked by Norton Anti-Virus 2002
>>> Tim Billingsley wrote:
> >
> > OK there are three recommendations for the 300+ doublet
> > http://www.cebik.com/edu6-1.gif can anyone tell me how to wind, make,
> > fabricate, produce, simulate, or otherwise come up with a 9:1 BalUn. I
run a
> > TS570S(G) and I don't believe it has any provision for a balanced
> > feedline(of course I am not staring at the back at the moment). I would
want
> > to utilize a BalUn and come into my shack with coax since I have
aluminum
> > siding, but not being an antenna Guru I am open to suggestions and
comments
> > on other alternatives ... after all that is why we are here I think.
> >
> > Thanks again for the information and I patiently await rhetoric
>> - - -
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> _______________________________________________
> Antennas mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/antennas

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