[Towertalk] choices

[Mark]

Just happens, I disagree .. no modeling, just experience, especially in
early 80s .. G5RV worky worky, but no way as good as a full real dipole,
with no antenna fuses holding up the parade .. really .. All this stuff
about antenna tuners, baluns, etc....... aaarrrgghhh .. perhaps some good in
it, but .. I just put up (low altitude) 75M  regular old dipole . like I did
in the early 60s... Hy-Gain antenna insulators .. fed with RG-214 .. no
balun, no beads, but everything done "correct" as we were taught back when
.. soldered, insulated, protected from wx .. works better than any da*n
aerial you can put up at that level, for that purpose . also, have verts .
which beat out the standard old dipole, SOMETIMES .. and, yeah .. shootin'
skip for EU, or JA .. but, only .. SOMETIMES.
Wish I could have the height for 1/4 lamda slopers I had back when .. those
CLEANED THE CLOCK of the G5RV crowd.  Now, not putting down the G5RV ////
just saying, t'ain't necessarily as good as it seems .. remember how many
YUGO owners swore by their auto, for 2 or 3 weeks, until they swore AT it ..
HI HI .. 73, Y'all .. Mark .. AA6DX
----- Original Message -----
From: "Chuck Counselman" <ccc@space.mit.edu>
To: <towertalk@contesting.com>
Sent: Wednesday, October 09, 2002 10:24 AM
Subject: RE: [Towertalk] choices


> Steve Katz <stevek@jmr.com> wrote:
>
> >As Tom Schiller N6BT wrote in his QST article two years ago, "Everything
> >Works," and he used a post-mounted light bulb as an example....
>
> I know; I read that article, and we've all seen or heard examples,
> sometimes first-hand, of contacts made with practically no antenna.
>
> And I agree with you that it pays to have multiple antennas, and a switch.
>
> It is silly to regard a G5RV as a "leaky dummy load," as someone else
> just did on this reflector.  A G5RV is very nearly (like, within 1
> dB) as good as effective a full half-wavelength dipole at the same
> height.  A regular G5RV is a center-fed horizontal wire doublet 102
> feet long, which is about 25% shorter than a full half-wavelength for
> 80 meters.  It is resonated by what amounts to a series "loading"
> inductor at its center.  This inductor is not a coil, but 30 feet of
> open-wire transmission line.  This inductor is essentially lossless.
>
> There is practically *no* difference in efficiency or gain or pattern
> shape between a G5RV and a "full" half-wave dipole.  The only
> noticeable difference is that the G5RV has a lower radiation
> resistance (seen at the wire feedpoint), so its Q is higher.  But its
> radiation resistance is not much lower (IIRC, it's around 35 ohms,
> vs. maybe 72 ohms for a dipole), so there's no difficulty matching it
> with a tuner.
>
> You can see all this in a NEC-4 simulation, which I have done.  But
> of course the proof is on-air performance.
>
> Although I don't have another antenna here for "A-B" comparisons, I
> participate in a weekly 80-m net (the Wireless Set No. 19 Group CW
> Net) that includes several other stations in my area (within 500 km);
> and occasionally we get a check-in from far away (the last one was
> GI3PDN, last month) who gives us all signal reports.  The two
> stations who get the best reports are W1NU and I.  Both of us use
> G5RVs.  (W1NU averages about 1 S-unit better than I, which is not
> surprising because his antenna is higher than mine.  He is also on a
> salt marsh!)  The other stations use full-size dipoles, an 80/40
> trapped dipole, and an 80-m Windom.  We all run about the same power.
> Our antenna heights average about 30 feet.  W1NU's G5RV, rigged as an
> inverted-V with apex at 55 ft. is the highest.  Mine is rigged as an
> inverted-U with its central 68 feet horizontal at 30 feet height.
>
> I've been in this net almost every week for three years, and I always
> log the signal reports.  W1NU is almost always on top, and I'm almost
> always runner-up.  IMO, this body of evidence is about as meaningful
> as "A-B" comparisons at a single station.
>
> If I had room for a full-size dipole, I'd use one.  If I had good
> soil conductivity and room for the radials, I'd use a vertical.  But
> a G5RV, including one rigged as an inverted-V, is _not_ an
> inefficient antenna, and no one should avoid using it because of
> comments like "I wouldn't mount a G5RV as an inverted vee; actually a
> G5RV's not much of an antenna on 80m at all, so I wouldn't bother
> with it."