Hi Charlie,
the mast for his inv-V snapped during Hurricane Sandy and I attached
the apex to the highest remaining part of the PVC mast that snapped,
that I can reach up to. So for this moment, his Inv-V is more of a
dipole with the apex 10-15 foot higher than the terminations. Next
summer I'll wrangle the original assembly up for him and the apex
will be another 30' higher than it is now.
I had to fell a few trees that were interfering with the wires and
now he has a clear space with no more interference. So no high
conditions here, my INV-L is based 20' lower than the basement 350'
away and is at the edge of a salt marsh with the wire over the tree
tops. The highest part of my vertical run is maybe 20' higher than
the apex of his V is today. No possible way to put up anything taller
for either of us, no towers allowed. It's still a nice location
though on the end of Long Island sound.
73,
Gary
KA1J
> Hi, Gary
>
> Should do fine! The W2DU balun is a good current-mode design by
> someone who
> knew what he was doing!
>
> As for 160, I do have a W2DU current mode balun, from Unadilla that
> is
> longer that the 80-10m version (more beads) but I never really
> pushed it. I
> did use it some n 80m. Actually on 160, I didn't really have need
> for a
> balun with the inverted L antennas that I used. I expect that the
> application for a 160 m balun is most likely for guy s with high
> dipoles and
> inverted Vees, and really big delta loops. The w2DU balun will
> workat least
> as well as, and probably better than, the W2AU balun that it woud
> be
> replacing!
>
> Hope your dad enjoys it for many more years! :-)
>
> 73,
> Charlie, K4OTV
>
>
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of
> Gary
> Smith
> Sent: Sunday, October 27, 2013 7:45 PM
> To: Topband@contesting.com
> Subject: Re: Topband: Balun Question
>
> Fellows,
>
> Thanks for the on & off list replies, I just got back from a weekend
> away & read through them all. Part of me wants to just leave it as
> is
> but that's not practical, a good icing and the connections I made
> will fail. Since I need something to relieve stress from the
> copperweld and the weight of the coax, the W2DU 1:1 looks like it
> ought to cover the issues.
>
> There's no telling when bad weather will hit and once there'ssnow on
> the roof I'm not going up to work on anything so I need to do it
> now.
> He only operates on 80M phone using a Viewstar PT-2500A amp so the
> W2DU 1:1 ought to be fine. Someday when I'm the one using the
> station
> I'll want to use it on 160 and I'm not sure how well that balun will
> do on 160 but that's for another time.
>
> Thank you all for the thoughts and helpful suggestions.
>
> 73,
>
> Gary
> KA1J
>
> > Unfortunately, optimum balun impedance and design really depends
> > heavily on
> > the application,. There is no magic design that works best for
> all
> > applications, and the issue is so complex that almost any
> article
> > falls
> > short.
> >
> > For example, the 5000 ohms pure R will not work at 1500 watts
> with
> > all
> > antennas. With a balanced feeder having a balun termination
> > impedance of
> > 2000 ohms, a balun would have 1732V RMS between conductors, and
> 866
> > volts to
> > ground. CM voltage would be 866 across a perfect balun if the
> feeder
> > were
> > perfectly balanced. The 5000 ohm CM impedance balun would
> dissipate
> > 150
> > watts in the cores, far beyond what any reasonable core stack
> would
> > tolerate. The fact the antenna comes out of balance reduces the
> heat
> > somewhat, but this clearly is a case where we WANT a reactive
> > isolation
> > impedance to reduce heat.
> >
> > Making things worse, a half wave antenna fed through 1/4 wave of
> > open wire
> > might have an impedance of 6000 ohms or more. The above example
> was
> > for 2000
> > ohms!
> >
> > Without much effort, we can see why simplistic "always do this"
> > rules just
> > don't work in the real world.
> >
> > Every situation has to be case-by-case.
> >
> > 73 Tom
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Tom Boucher" <tom@telemetry.demon.co.uk>
> > To: "160 reflector" <topband@contesting.com>
> > Sent: Friday, October 25, 2013 10:49 AM
> > Subject: Topband: Balun Question
> >
> >
> > > Gary KA1J - take a look at this excellent article on ferriste
> > baluns by
> > > GM3SEK:
> > >
> > > http://www.ifwtech.co.uk/g3sek/in-prac/inpr1005_ext_v2.pdf
> > >
> > > 73
> > > Tom G3OLB
> > > _________________
> > > Topband Reflector
> > >
> > >
> > > -----
> > > No virus found in this message.
> > > Checked by AVG - www.avg.com
> > > Version: 2014.0.4158 / Virus Database: 3614/6767 - Release
> Date:
> > 10/20/13
> > >
> >
> > _________________
> > Topband Reflector
> >
>
>
>
> _________________
> Topband Reflector
>
>
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