The G5RV antenna can be found by googling. Anyone using this
arrangement. It uses a coax feed to balanced feed (which variously acts
as radiating elements, depending on the band). The author says a balun
is not needed but then describes an RF choke that sounds a lot like a
balun. I am also concerned about TVI with this system.

John

The choke balun is used because the G5RV is fed with balanced line. They
work well, last a long time and require a tuner. I have never had any TVI
with one, nor did I ever expect any.

"jawod" wrote in message
...
The G5RV antenna can be found by googling. Anyone using this
arrangement. It uses a coax feed to balanced feed (which variously acts
as radiating elements, depending on the band). The author says a balun
is not needed but then describes an RF choke that sounds a lot like a
balun. I am also concerned about TVI with this system.

John

jawod wrote:
The G5RV antenna can be found by googling. Anyone using this
arrangement. It uses a coax feed to balanced feed (which variously acts
as radiating elements, depending on the band). The author says a balun
is not needed but then describes an RF choke that sounds a lot like a
balun. I am also concerned about TVI with this system.

http://www.cebik.com/wire/g5rv.html

http://www.vk1od.net/G5RV/
--
73, Cecil http://www.qsl.net/w5dxp

jawod wrote:

The G5RV antenna can be found by googling. Anyone using this
arrangement. It uses a coax feed to balanced feed (which variously acts
as radiating elements, depending on the band). The author says a balun
is not needed but then describes an RF choke that sounds a lot like a
balun. I am also concerned about TVI with this system.

John


I'm not crazy about them at all. I'm not a fan
of switching feedline types midroute to the antenna.
This applies to other antennas as well. The G5RV
was designed mainly as a 20 meter antenna. I'm
not sure who decided it was the magical platform
for a multiband antenna, but someone did...
Someone should get a rope I think... :/
You would be much better ditching the coax and
choke, and running straight ladder line, if feeding
all bands with a tuner. I think coax fed antennas
should see a proper match at the feedpoint of
the antenna. If I'm going to use coax, I'm going to
run coax the whole way.
Some run the "carolina" windoms the same way pretty
much.. I've directly tested simple coax fed
dipoles against both of these antennas. It was
fairly ugly. The simple dipole thrashed both of them
handily. There is a good bit of loss in all that
feedline clutter. Some bands worse than others.
If you are going to run a tuner and ladder line for
all band use, a simple dipole on the lowest band
to be used is a fairly decent compromise. No need
to add excess feedline clutter. And loss.
If you use ladder line all the way, and tune carefully
using the least inductance, you will have a
fairly efficient system on most all the bands.
Most tuners include a 4:1, but some prefer a 1:1
balun instead.
MK



--
http://web.wt.net/~nm5k

To summarise - dump it !

If SETUP right , There the best HF I've ever used.

Ricke wrote:
If SETUP right , There the best HF I've ever used.

Maybe the only one? :-) The G5RV, with tuner, is a pretty
good 80m, 40m, 20m, and 12m antenna. If the series section
is varied from 20 feet to 36 feet, it becomes a very good
all-HF-band antenna. With the addition of a parallel 1000pf
capacitor with the series section at 22 feet, on 75m my "G5RV"
has SWR of 1.3:1 and works as well as a 75m 1/2WL dipole.
--
73, Cecil http://www.qsl.net/w5dxp

Maybe the only one? :-) The G5RV, with tuner, is a pretty
good 80m, 40m, 20m, and 12m antenna.

Depends what you compare it to... I bet my paralleled
80/40/20 dipoles would beat it on all those bands.
Maybe even 12m. I'm not going to lose too awful much
even though I'm running 213 coax. You may have some
cases on the higher bands where the gain may be
better than the dipoles in some directions, but thats still
not a matter of efficiency.

If the series section
is varied from 20 feet to 36 feet, it becomes a very good
all-HF-band antenna. With the addition of a parallel 1000pf
capacitor with the series section at 22 feet, on 75m my "G5RV"
has SWR of 1.3:1 and works as well as a 75m 1/2WL dipole.

You would be the exception to the rule. And I still really doubt
it's the total equal of a simple coax fed dipole on 80m.
The "usual" G5RV that most people tend to buy and run
is one of the most pathetic 80m antennas I've ever used
in my life. Truly a disgusting POC... I had the mispleasure
of being stuck on the G5RV at not one, but two field days
in a row. I'd never experienced working FD on a dummy
load until that time. I lost about 3 mm of tooth due to the
constant grinding of my teeth on those weekends.
After that, I *swore* I would never, ever, be stuck on
one of those things ever again. Never, nada, zilch.
Now, I've heard people that had fairly decent signals
with various perversions of the G5RV, but again, they
seem to modify them to work halfway well, and many
run amps, which also help them look a bit better than
they really are. If people want to run those, be my guest,
but keep them at least 500 yards from me. I'll be using
my usual coax fed dipoles.
This trails off to the "carolina" windoms that many people
run in the same appx manner.
Well, on the first FD after the two G5RV nightmares,
I brought all my own stuff to build dipoles on the spot.
I got to the FD, and the first antenna they suggested I
use was a carolina windom that was up in the air
pretty well. Maybe 50 ft up or more. It was fed with
the usual "clutter" and a tuner. "tuner/coax/choke/antenna.
I can't remember if any ladder line was involved on
that one...
Anyway, the first thing out of my mouth was *NO!!!!!".
I'll build a regular ole dipole, thanks, but no thanks.
Not trying to be rude, but I'd had my fill of dummy loads.
Anyway, I built a 40 meter dipole on the spot, and
threw it up in a different tree. It was actually lower
in height than the windom. I then brought out a coax
switch, and hooked both the windom, and the coax
fed dipole to the rig. Now, at first glance, you
would think the windom was doing all the good.
It was "working", and seemed to be just fine.
But then, I'd switch over to the dipole, and
*everything* would jump 2 S units on that radio.
All signals, noise floor, the whole shooting match.
The windom owner like to fell over. He had no
idea that he was taking that big a hit vs a simple
dipole. Needless to say, the windom wasn't used
after that test. People can run whatever they want,
but many have delusions that these "compromise"
clutter fed all band antennas are just as good as a
simple dipole. It's rarely the case by what I've seen.
Did you actually compare with a coax fed dipole
using a switch, etc? If not, saying it's equal is
just theory at this point. I'd have to see it to believe
it... :/ Heck, I see the difference from a properly fed
tuner/ladderline/dipole setup vs a coax fed dipole.
The coax fed always wins here by a slight amount.
As far as I'm concerned, a coax fed dipole is as good
as you can get in the real world on those lower bands as
far as system efficiency. In the 95+% bracket I think.
Your tunerless setup may be equal, but that's
not the usual setup for most people. Most use
a tuner also. I use the coax fed dipole as the benchmark
by which all others are measured on 80m. Most all lose,
unless they are a gain antenna like arrays or whatever.
Of course, with the dipoles on 80m, I'm usually talking
NVIS, or medium distances. I'm not a dxer much.
But...I had no problem at all taking to EU this past
winter on that dipole in the couple of times I tried
it down in the dx window. . No amp. I haven't run an amp
in 5 years. First call and solid copy too. I forgot where
they were. I think one on G land. One in Spain, germany,
etc..With just 90-100w from the 706. But a big NVIS
signal is really what I shoot for. Can't get much better
than a coax fed dipole or loop. Simple is best I think.
MK

On Mon, 09 Jan 2006 15:50:20 GMT, Cecil Moore wrote:

Ricke wrote:
If SETUP right , There the best HF I've ever used.

Maybe the only one? :-) The G5RV, with tuner, is a pretty
good 80m, 40m, 20m, and 12m antenna. If the series section
is varied from 20 feet to 36 feet, it becomes a very good
all-HF-band antenna. With the addition of a parallel 1000pf
capacitor with the series section at 22 feet, on 75m my "G5RV"
has SWR of 1.3:1 and works as well as a 75m 1/2WL dipole.

Now that is one of those things about a G5RV, no two are alike.

What are the key factors that "define" a G5RV? The things that I
recall from Varney's article we

- 31m long dipole
- centre fed
- flat top / inverted V
- open wire section of half wave length on 20m, from his physical
description, Zo about 520 ohms, but IIRC he suggests Zo is not
critical
- undefined length of either coax of open wire line of undefined, but
low Zo (50 - 120 ohms though he seemed to think figure 8 flex has a
lower Zo than it probably does).
- balun or no balun at the coax to open wire line transition,
depending on his article, he changed his mind.

My question is how many of these characteristics can be dispensed
with, or varied significantly and still legitimately speak of it as a
G5RV?

I am watching the argument between those who swear by a G5RV and those
who swear at a G5RV and suspect that one of the reasons (and not the
only reason) is they are not talking about the same thing.

There is a tendency to call anything with a ~30m centre fed dipole a
G5RV, and yet that component's pattern is independent of everything
else (excluding feedline radiation) and its efficiency is quite good
independently of everything else. It is "everything" else that
contains the losses that result from the dipole's feedpoint load
impedance, and it is the "everything else" that makes or breaks the
antenna.

Owen
--

On Mon, 09 Jan 2006 15:50:20 GMT, Cecil Moore wrote:

Ricke wrote:
If SETUP right , There the best HF I've ever used.

Maybe the only one? :-) The G5RV, with tuner, is a pretty
good 80m, 40m, 20m, and 12m antenna. If the series section
is varied from 20 feet to 36 feet, it becomes a very good
all-HF-band antenna. With the addition of a parallel 1000pf
capacitor with the series section at 22 feet, on 75m my "G5RV"
has SWR of 1.3:1 and works as well as a 75m 1/2WL dipole.

Is this the antenna described at http://www.qsl.net/w5dxp/G5RV.HTM ?

In that article, on 75m you model a feedpoint impedance of 36-j324,
28' of 300 ohm ladder line, for a Z of 15+j4 (seems to indicate 46.7
deg length of 300 ohm line with 0.007dB loss (optimistic)).

At that point, were 50 ohm coax connected directly, the VSWR at the
load end of the 50 ohm coax would be 3, however you shunt the 17+j4
with 1000pF to give a new Z of 12.5-j8 that results in a VSWR at the
load end of the 50 ohm coax of around 4.1, driving a little more loss
into the coax section.

Presumably when you say that the capacitor improves the VSWR on 75m,
you mean the VSWR on the coax. Did I miss something, how does the
capacitor improve the VSWR on 75m?

Owen

PS I couldn't make the numbers work for 22' as in your quote, where I
got a VSWR at the load end of the coax of 27. I couldn't see where the
VSWR of 1.3 comes from?
--