[Towertalk] GAO Challenger DX

[Jim Shaw]

Nice backup antenna! I had a 5BTV installed in a similar fashion 25 years
ago.  Seemed just fine to me.  Never had any trouble with the traps (but was
only running 100 watts).  Great antenna.

73 de Jim WA6PX
JGShaw@Alumni.HAAS.org

-----Original Message-----
From: Steve Katz [mailto:stevek@jmr.com]
Sent: Monday, October 07, 2002 1:19 PM
To: 'Jim@ShawResources.com'; Tower
Subject: RE: [Towertalk] GAO Challenger DX


Hi Jim,

Oh, I'm a firm believer in elevated verticals and resonant radial systems.
I use one myself, at home, to supplement my beams and also to work DX on
40m, for which I have no beam.  It's a simple 6BTV Hustler (27' tall or so),
base fed, over sixteen radials, all of which are tuned, and sloping down
below the feedpoint, which is about 25' above ground.

It works well, especially for the minimal investment it represents.

Using the same set of radials, which represent the majority of the
investment in this system, I'm sure it would work fine with a SteppIR
vertical, too.  But the 6BTV only costs $199, covers six bands, and requires
zero time to change bands, while occupying virtually the same space and
windload as what you propose.  The single SteppIR vertical (not that I've
ever seen one) would be somewhat more efficient as I understand the only
thing in the current path is copper foil, with no traps or other devices to
potentially introduce loss; however, I'd estimate that the efficiency
differential is only about 1 dB or so, maybe not worth worrying about.

I've attached a photo of my own 6BTV installation, which, I'm sure you'll
agree, works because of the installation more than because of the
radiator...

73,

Steve, WB2WIK/6

 <<Roof tower photo.jpg>>

"If everything seems under control, you're just not going fast enough." -
Mario Andretti

> -----Original Message-----
> From:	Jim Shaw [SMTP:Jim@ShawResources.com]
> Sent:	Monday, October 07, 2002 12:52 PM
> To:	Steve Katz; Tower
> Subject:	RE: [Towertalk] GAO Challenger DX
>
> Steve
> OK, but here's one more wrinkle to consider.  The SteppIR single 33 ft
> high
> self supporting radiating element has minimal wind resistance and can be
> roof mounted (or chimney?).  So, ground radials aren't involved if done
> this
> way.
>
> Further, according to some credible articles, elevating a vertical, or at
> least its radials, even just a little bit, usually pays dividends. So much
> so that maybe 4 or, at most 8, radials per band would provide as good or
> better ground than 45 or more buried radials.  The last reference listed
> below is so adamant about this that it specifically states that one of the
> "lessons learned" from the expedition was "Under most any circumstance,
> radials should be elevated".
>
> I know there is some controversy about the value of elevating a verticals
> (or at least the radials), but I would appreciate learning more.  Please
> fire away.  BTW, here are the references so you can check them out
> yourself
> and see if I am misreading them.
>
> 1-"Elevated Vertical Antenna Systems: Is your vertical system performance
> up
> to snuff?  If not, maybe it needs a lift - in elevation above ground that
> is!". (ARRL "Vertical Antenna Classics, KB8I, pg 108).
>
> 2-"Elevated Vertical Antennas for the Low Bands: Varying the Height and
> Number of Radials" by KB8I, The ARRL Antenna Compendium - Vol 5.
>
> 3-"Vertical Dipoles and Ground Planes: What Antenna Modeling Reports" by
> W4RNL available online at http://www.cebik.com/vdgp.html
>
> 4-"Verticals for Contest Expeditions: Learnings from the 6Y4A CQ WW CW
> Contest" By Kenny Silverman, K2KW and Tom Schiller, N6BT.
>  http://www.k2kw.com/verticals/learning.html
>
> 73 de Jim WA6PX
> JGShaw@Alumni.HAAS.org
>
> -----Original Message-----
> From: Steve Katz [mailto:stevek@jmr.com]
> Sent: Monday, October 07, 2002 11:49 AM
> To: 'Jim@ShawResources.com'
> Cc: 'towertalk@contesting.com'
> Subject: RE: [Towertalk] GAO Challenger DX
>
>
> Good comments, Jim (below).
>
> However, it seems to me the SteppIR approach probably requires as
> extensive
> a radial field as any other multiband vertical, and that's most of the
> work
> for many of us (including me).  If I'm spending a few weekends laying
> radials in such a way they won't be tripped over, cut by the gardener,
> etc,
> at that point I may as well install a multi-band linear-loaded (or
> equivalent) vertical to cover several bands instantly, without the "wait"
> or
> complexity of a motor driven radiator.
>
> But, that's just me...
>
> WB2WIK/6
>
> > -----Original Message-----
> > From:	Jim Shaw [SMTP:Jim@ShawResources.com]
> > Sent:	Monday, October 07, 2002 11:17 AM
> > To:	Steve Katz
> > Subject:	RE: [Towertalk] GAO Challenger DX
> >
> > Steve
> > Perhaps to test your statement "if I had to choose just ONE good 40m
> > system
> > to
> > stick with forever, I'd use a full-sized vertical", SteppIR introduced a
> > full size 1/4 WL (33 feet) 40M vertical that also mechanically shortens
> > itself to be full size on 30 - 10 meters.  Unlike Force12 vertical
> > dipoles,
> > the SteppIR vertical requires radials but appears to be a good choice
> for
> > multiband capability especially when compared to others using traps,
> > capacity hats and other approaches to achieve multiband performance.
> The
> > SteppIR vertical appeals to me due to its simplicity: It has just a
> single
> > radiating element (but it probably requires more geography due to the
> use
> > of
> > radials).
> >
> > http://www.steppir.com/
> >
> > Now I'm torn between getting a couple of Force12 vertical dipoles (to
> > cover
> > 40 & 20-10M) or taking the SteppIR single 'vertical' plunge (which will
> > provide me 30M coverage as well).
> >
> > 73 de Jim WA6PX
> > JGShaw@Alumni.HAAS.org
> >
> > -----Original Message-----
> > From: Steve Katz [mailto:stevek@jmr.com]
> > Sent: Monday, October 07, 2002 10:37 AM
> > To: 'Jim@shawresources.com'; TOWERTALK@contesting.com
> > Subject: RE: [Towertalk] GAO Challenger DX
> >
> >
> > Interesting comments, Jim.
> >
> > I don't have a 40m beam, myself, but we do at the contest station (K2XR)
> > and
> > always maintain some vertical antennas to supplement the beam.
> >
> > The 2L 40 at 90' works well; however, using a GAP Voyager
> (ground-mounted,
> > obviously) or wire slopers off the 140' tower at the site are great
> > "go-to"
> > antennas that can easily outperform the 2L beam on occasion, depending
> on
> > propagation and path.  To use just the beam, always, would be silly.  I
> > find
> > myself frequently switching to the Voyager or a sloper, to see which
> works
> > best for a given DX contact, and use that one to make the call.
> >
> > Based on my various experiences in winter-months DX contesting from
> > stations
> > having a mix of antennas, if I had to choose just ONE good 40m system to
> > stick with forever, I'd use a full-sized vertical like the Voyager for
> > transmitting, and a couple of Beverages, or a small rotary loop, for
> > receiving, most of the time.  Only problem with the vertical appears to
> be
> > that DX signals are all "S9+" and so is the noise....
> >
> > WB2WIK/6
> >
> > "If everything seems under control, you're just not going fast enough."
> -
> > Mario Andretti
> >
> > > -----Original Message-----
> > > From:	Jim Shaw [SMTP:Jim@shawresources.com]
> > > Sent:	Monday, October 07, 2002 10:08 AM
> > > To:	TOWERTALK@contesting.com
> > > Subject:	RE: [Towertalk] GAO Challenger DX
> > >
> > >
> > > In general, I agree that the big variable at low heights (less than
> 1/2
> > > WL)
> > > is the ground. Always thought low HF horizontal dipoles are DX
> > > problematic,
> > > particularly on the low bands.
> > >
> > > Its not clear to me if you are restricting your points to traditional
> > 1/4
> > > WL
> > > verticals with radials, or if you intended the comments to apply to
> all
> > > verticals including 'vertical dipoles'.
> > >
> > > I have been real interested in the FORCE12 move into 'vertical
> dipoles'
> > of
> > > one flavor or another.
> > >
> > > (See http://force12inc.com/sigmainfo-005.htm)
> > >
> > > They managed to get a positive QST review (OCT 2002) on their
> 'stealth'
> > > Sigma 5 (9 ft or so high radiator on 20-10M). But they have several
> > > 'fuller
> > > size' models that they claim are 'DX-pedition proven'.  And, although
> it
> > > may
> > > be marketing hype (aimed at GAP?), they claim very high efficiency for
> > > their
> > > vertical dipoles even when mounted just above the ground!  Their use
> of
> > > 'capacity hats' to shorten their vertical dipoles seems quite
> practical
> > to
> > > me as it avoids the issue of traps.
> > >
> > > A consideration in favor of vertical vs horizontal dipoles for DX
> (e.g,
> > on
> > > 80M where a 1/2 WL 80M dipole is 140 ft) is that dipoles must be
> > rotatable
> > > to achieve omni directional coverage.  Or you may need two or three to
> > > cover
> > > all directions.  Even with efficient shortening, they can be
> > > geographically
> > > problematic as well as difficult to get high enough.  But, for those
> > able
> > > to
> > > use 'brute force', these are not issues.
> > >
> > > To me, each has pros and cons and circumstances will tend to result in
> > > choosing one over the other.  I try to know the strengths and
> weaknesses
> > > of
> > > each so I can use the best for the situation.
> > >
> > > 73 de Jim WA6PX
> > > JGShaw@Alumni.HAAS.org
> > >
> > > -----Original Message-----
> > > From: towertalk-admin@contesting.com
> > > [mailto:towertalk-admin@contesting.com]On Behalf Of n4kg@juno.com
> > > Sent: Monday, October 07, 2002 6:23 AM
> > > To: TOWERTALK@contesting.com
> > > Subject: Re: [Towertalk] GAO Challenger DX
> > >
> > >
> > > Ground Reflections from Horizontally Polarized antennas are
> > > very efficient, suffering only 1 to 2 dB loss regardless of how
> > > poor the conductivity of the ground.
> > >
> > > Ground Reflections from Vertically Polarized antennas are
> > > HIGHLY dependent on the ground conductivity and are typically
> > > much higher than for horizontally polarized antennas unless the
> > > reflections are over Salt Water.
> > >
> > > On the Low Bands, verticals are often better than (low) dipoles
> > > for DX where a 1/2 WL high 80M dipole needs to be 140 ft up!
> > >
> > > Tom  N4KG
> > >
> > >
> > > _______________________________________________
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