In my case, regarding my question earlier today, I don't need actually any
choke or balun. I'm just trying to learn, the theory.
Thanks
73, Maximo
________________________________
De: guyk2av@gmail.com <guyk2av@gmail.com> en nombre de Guy Olinger
<k2av@contesting.com>
Enviado: lunes, 20 de marzo de 2017 10:51
Para: Máximo EA1DDO_HK1H
Cc: jim@audiosystemsgroup.com; TowerTalk@contesting.com
Asunto: Re: [TowerTalk] current balun question
On Mon, Mar 20, 2017 at 3:12 AM, Máximo EA1DDO_HK1H
<ea1ddo@hotmail.com<mailto:ea1ddo@hotmail.com>> wrote:
By "effective," I mean a choke that has a very high common mode
resistive impedance at the operating frequency.
Indeed.
But this is THE monkey wrench in the works for a lot of folks, possibly
including the original poster on this thread. On the lower bands, a lot of "all
band" chokes have very little blocking. I've measured one as low as 173 ohms on
160 meters. Store bought devices vary all the way from cr*p to really very well
done devices designed for specific purposes from Balun Designs, who in my mind
right now is the Cadillac manufacturer of such stuff [disclaimer: no commercial
interest here].
OCF applications put a very large strain on choking devices, and really must be
done exactly right to stay away from loss. A few of us have accumulated a
collection of amusing "flaming balun" stories from around the country, where
the accumulation of heat in the enclosure eventually set all the plastic on
fire.
"Honey, there's something on fire up on your tower. And it smells bad."
For a while the North Carolina chapter of PVRC, upon provocation, would present
something called the N4AF Flaming Balun Award for various destructive RF faux
pas. You can guess the rest.
Don't be looking for a cheeep way out, or to reuse a "junk box balun" that you
can't think of any other use for, that you wish someone would tell you it's OK
to use.
Go buy something MADE FOR the application and frequency. Then string it up and
go have fun.
73, Guy K2AV
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