The so-called current balun is only immune to saturation with respect to
the normal transmission line mode signal where the fields from the two
conductors are out of phase and cancel. With respect to common mode
components that the balun is designed to suppress, it still has to provide
choking action and is therefore susceptible to saturation, material losses,
etc. A good but slightly bulky solution to this problem is the air-wound
choke which is nothing more than a current balun that doesn't rely on
a high permeability ferrite to achieve the required common mode
impedance. They just take up more space than their ferrite counterparts
(especially at low frequencies).
73 de Mike, W4EF..............................
----- Original Message -----
From: "John Petrich" <petrich@u.washington.edu>
To: <towertalk@contesting.com>; "Fred Hopengarten" <k1vr@juno.com>
Sent: Wednesday, April 24, 2002 9:02 PM
Subject: [Towertalk] HyGain Balun
> Tower talkers,
>
> Have been following this thread with interest. The original question
of
> whether to reinstall the HyGain BN-86 voltage balun or to replace or even
> supplement that balun with a current balun is an excellent question and
gets
> to the heart of the question of what elements contribute to a modern high
> performance antenna system. The idea that "a balun is a balun is a
> balun..............." is simply not consistent with contemporary
engineering
> knowledge and practice. Maximum antenna performance is only possible with
> careful attention to the feedline / antenna transition.
>
> Simply put, the purpose of a balun is to create conditions at the
> antenna feedpoint such that the transmission line acts solely as a
> transmission line (not an antenna in it's own right), and the antenna
> performs as originally designed. Under certain conditions, a balun can be
> dispensed with if careful attention is paid to the transmission line
> installation. This approach is a highly specific for each installation,
is
> inherently narrow band and less than ideal for most triband and multiband
> antenna installations.
>
> The BN-86 voltage balun is a good example of the style of balun once
> popular in amateur antenna installations. This style of balun is
> characterized by limited common mode or choking impedance (a.k.a."balun
> action"), a vulnerability to "saturation" of the ferrite core, and
> relatively narrow bandwidth compared to the alternatives. When originally
> popularized, this style of balun was a useful advance in antenna
technology.
>
> The modern ferrite core current balun is an adaptation of an
alternative
> style balun based on the principle of non-flux linked transmission line
> transformers. These baluns offer a relatively high choking impedance,
> relative immunity to "saturation" of the ferrite components, and extremely
> wide bandwidths. They are simple to construct, rugged and weather
resistant
> if constructed carefully.
>
> The BN-86 balun doesn't need to be replaced if it is in working order
> and the owner is satisfied with the antenna performance. If the owner is
> uncertain whether the balun is in working order, unsure whether the
antenna
> is handicapped by poor balun performance, or if he or she wants insurance
> that what ever balun in use is offering the "latest and the greatest"
> performance, by all means, replace with a current balun as described
below.
> Installing both a voltage and a current balun is probably not a good
> approach because some of the inherent limitations of the voltage balun,
i.e.
> "saturation" potential, will remain.
>
> I'm certainly interested in feedback from others if these ideas are
way
> off base or not.
>
> Regards,
>
> John Petrich, W7FU
>
>
> ----- Original Message -----
> From: "Fred Hopengarten" <k1vr@juno.com>
> To: <towertalk@contesting.com>
> Sent: Wednesday, April 24, 2002 7:46 PM
> Subject: Re: [Towertalk] Re HyGain Balun
>
>
> > I have two HyGain TH6DXX and two HyGain TH7DX antennas in the air. I
made
> > up little plastic boxes from Radio Shack, mounted SO-239's and stainless
> > steel studs (1/4-20 bolt and nuts) wired it to be the equivalent of
> > splaying the coax (I was worried that it is hard to pevent water from
> > getting into the coax and I preferred the ease of a PL-259/SO-239 when
up
> > in the air). Each coax has 6-7 toroid beads on the RG-213. Remember to
> > put on the beads before the PL-259 (I own that T-shirt), or pay more for
> > split beads (cheaper than re-doing the PL-259's, if you value your
time).
> >
> >
> > I have removed the BN-86's from service.
> >
> > Fred Hopengarten K1VR hopengarten@post.harvard.edu
> > Six Willarch Road * Lincoln, MA 01773-5105
> > 781/259-0088 *eFax 419/858-2421
> >
> > ________________________________________________________________
> > GET INTERNET ACCESS FROM JUNO!
> > Juno offers FREE or PREMIUM Internet access for less!
> > Join Juno today! For your FREE software, visit:
> > http://dl.www.juno.com/get/web/.
> > _______________________________________________
> > Towertalk mailing list
> > Towertalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
> ----- Original Message -----
> From: "Fred Hopengarten" <k1vr@juno.com>
> To: <towertalk@contesting.com>
> Sent: Wednesday, April 24, 2002 7:46 PM
> Subject: Re: [Towertalk] Re HyGain Balun
>
>
> > I have two HyGain TH6DXX and two HyGain TH7DX antennas in the air. I
made
> > up little plastic boxes from Radio Shack, mounted SO-239's and stainless
> > steel studs (1/4-20 bolt and nuts) wired it to be the equivalent of
> > splaying the coax (I was worried that it is hard to pevent water from
> > getting into the coax and I preferred the ease of a PL-259/SO-239 when
up
> > in the air). Each coax has 6-7 toroid beads on the RG-213. Remember to
> > put on the beads before the PL-259 (I own that T-shirt), or pay more for
> > split beads (cheaper than re-doing the PL-259's, if you value your time)
.
> >
> >
> > I have removed the BN-86's from service.
> >
> > Fred Hopengarten K1VR hopengarten@post.harvard.edu
> > Six Willarch Road * Lincoln, MA 01773-5105
> > 781/259-0088 *eFax 419/858-2421
> >
> > ________________________________________________________________
> > GET INTERNET ACCESS FROM JUNO!
> > Juno offers FREE or PREMIUM Internet access for less!
> > Join Juno today! For your FREE software, visit:
> > http://dl.www.juno.com/get/web/.
> > _______________________________________________
> > Towertalk mailing list
> > Towertalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
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