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

wrote:

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.

Not by enough to notice on the other end. The G5RV has
a slight amount of gain over your 40m dipole. It has
low loss on the ladder-line matching section and an SWR
of less than 4:1 on the RG-213 coax. Where are the losses?

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.

It's a 3/8WL dipole on 75m, fed with low-loss ladder-line,
a parallel door knob cap, and an SWR of 1.3:1 on the RG-213
coax. Where are the losses?

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.

Well, maybe. The one I bought in 1988 was well designed with
a w2du balun and RG-8x coax. It worked well with a tuner and
I made lots of improvements as I learned more about it.

There was probably something wrong with the particular G5RV's
that you have been exposed to.

Some people run a 4:1 balun at the coax/twinlead junction on
a G5RV. That's the absolute worst thing to do on 75m as the
impedance at that point is already low at 16 ohms.
--
73, Cecil http://www.qsl.net/w5dxp

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


I agree ...... the only HF wire antenna I have ever used. You have to pay
close attention to the matching at 20m and then it works great. I use 300
ohm ladder line for the feed as I find that works the best. Build one and
try it out .......then you can see for yourself.


--
Bill Booth VE3NXK
Sundridge ON, Canada
79.23.37 W x 45.46.18 N
FN05ns

Visit my weather WebCam at http://www.almaguin.com/wxcurrent/weather.html

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
--

Depends what you compare it to... I bet my paralleled
80/40/20 dipoles would beat it on all those bands.

Not by enough to notice on the other end.

So you say. If I can tell the difference between a tuner/
ladderline fed dipole vs a coax fed dipole, I bet I could
tell the difference. But I use the receiver, and switch
between the antennas. Much more accurate than
relying on reports.

The G5RV has a slight amount of gain over your 40m dipole.

That just means I'm almost sure to be louder in the
other two directions.. :/

It has
low loss on the ladder-line matching section and an SWR
of less than 4:1 on the RG-213 coax. Where are the losses?

At the ladderline/choke/coax junction I would suspect.



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.

It's a 3/8WL dipole on 75m, fed with low-loss ladder-line,
a parallel door knob cap, and an SWR of 1.3:1 on the RG-213
coax. Where are the losses?

Does that version use the choke? Being the data is incomplete,
hard to say at this point. But if there is loss, I can probably
find it.. :/

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.

Well, maybe. The one I bought in 1988 was well designed with
a w2du balun and RG-8x coax. It worked well with a tuner and
I made lots of improvements as I learned more about it.

Hummm...Does that mean it's not really a G5RV anymore?

There was probably something wrong with the particular G5RV's
that you have been exposed to.

No doubt about it.

Some people run a 4:1 balun at the coax/twinlead junction on
a G5RV. That's the absolute worst thing to do on 75m as the
impedance at that point is already low at 16 ohms.

I bet those did use a 4:1...Kinda makes sense as they were
the absolute worst wire antennas I'd ever used on 80m.
But like Owen points out, you have so many perversions
of the G5RV, it's hard to tell what is what. I *think* the
versions I used were made by the same company that
makes the carolina windoms, but not sure. I don't
really keep up with antennas I know I'll never be using.. :/
What boggles my mind is why people would want to use
a compromise antenna at a field day, when you have
enough room to fit 49 full size antennas... :/
Or at home for that matter.. If I have room for full size
antennas, I'm gonna use them. Life is too short for
compromise antennas. I guess I'm spoiled. I've never
had to run those funky things due to lot size, etc..
Even if I did, I think I could cook up something better
than the usual G5RV. Whatever I use will never mix
feedline types midroute to the antenna, I know that
for sure. It's like a crapshoot hoping things will pan
out at the junction. I couldn't live that way.
MK

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

Well, with G5RV himself recommending ladder-line all the way
to the transmitter (ARRL Antenna Compendium #1) "If this form
(of the G5RV) is employed, almost any length (of balanced line)
may be used from center of the antenna to the matching network
(balanced) output terminals", the paintbrush is pretty broad.

I started out with a standard G5RV and modified it on a per
band basis to perform on all eight HF bands. 36 ft. of ladder-
line works on both 40m and 17m, my two favorite bands. When I
switch to 75m, I use 23 ft. of ladder-line with a parallel
1000pf cap. I call that the *PC-50* point, the point at which
a (P)arallel (C)apacitor will cause a match to (50) ohms.
--
73, Cecil http://www.qsl.net/w5dxp

wrote:

W5DXP wrote:
It has
low loss on the ladder-line matching section and an SWR
of less than 4:1 on the RG-213 coax. Where are the losses?

At the ladderline/choke/coax junction I would suspect.

The only thing there that could be lossy would be the choke.
Why would a 1000 ohm choke be lossy?

It's a 3/8WL dipole on 75m, fed with low-loss ladder-line,
a parallel door knob cap, and an SWR of 1.3:1 on the RG-213
coax. Where are the losses?

Does that version use the choke? Being the data is incomplete,
hard to say at this point. But if there is loss, I can probably
find it.. :/

Yes, but the impedance at that point is very close to 50 ohms
and the choke has about 1000 ohms of choking impedance.

Well, maybe. The one I bought in 1988 was well designed with
a w2du balun and RG-8x coax. It worked well with a tuner and
I made lots of improvements as I learned more about it.

Hummm...Does that mean it's not really a G5RV anymore?

Call it a modified G5RV. It still looks like a G5RV.

Whatever I use will never mix
feedline types midroute to the antenna, I know that
for sure. It's like a crapshoot ...

Not a crapshoot at all - just an application of a series section.
Do you object to 1/4WL of 75 ohm twinlead feeding a full-wave loop?
--
73, Cecil http://www.qsl.net/w5dxp

Not a crapshoot at all - just an application of a series section.

I'm not really talking about yours though. I'm talking about
the "usual" G5RV that is fed with a tuner, etc, ad nausium.
Most people don't change sections when they change
bands. They just redial the tuner and go.
If you change very much with a G5RV, it's not a G5RV
anymore. IE: If you feed a 102 ft dipole with ladder
line, but no choke or coax, it's not a G5RV anymore.
It's a 102 ft dipole fed with ladder line.
A series transformer for a loop is not quite the same to
me as it's almost always a single band solution.
I won't be expecting that transformer to work for all bands.
Like I said, if the "G5RV" or others of it's ilk are appealing
to you, be my guest. But trying to talk me into using one,
or even accepting it as something I would actually use is
futile. :/
Tell me this...What is the advantage of using the choke,
coax, etc, vs just running straight ladder line the whole
way? If I had to tuner feed a 102 ft dipole for all bands, thats
the way I would do it. There would be no coax, or choke.
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.

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?
--

On Tue, 10 Jan 2006 21:14:40 GMT, Owen Duffy wrote:

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 ?

I have made a mistake during my analysis, let me try again:

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 48.2
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 17.3-j3.0 that results in a VSWR at the
load end of the 50 ohm coax of around 2.9, almost identical to the
case without the capacitor.

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?
--
--