On second thought -
If you feed it like that, then it will cease to be a G5RV.


"pegge" wrote in message
...
someone tried to feed a type g5rv antenna with ´european´ zip-cord ?
(european meaning double the Volts compared to USA, thus half amps
for the same lamp wattage)
Would yield a simple ant, peel the first say abt 15- 17 meters, splitting
them up to the dipole part and the the rest X meter to a balanced tuner
etc.
sorry if this has been up too many times, search did´nt give a clue!

Tnx for info, 73 Per / sm7aha malmo, sweden

On Wed, 13 Jul 2005 17:40:02 -0400, "Hal Rosser"
wrote:


I think he was correct about the half-wave length of feedline:
according to the ARRL Antenna Book - 17th edition copyright 1994 - page
24-12 in chapter 24, under the Heading "Special Cases" and under the
sub-heading "The Half-WaveLength Line", it pretty clearly states that
regardless of z, it will be the same on both ends of a half-wave line. and
sections having such length can be added or removed without changing the
load Z. (as long as loss is negligible)

Also - You don't need to know the VF if you use a dip meter (or MFJ 259) -
And he would want the length to be half-wave so as to be able to ignore the
characteristic impedence of the zip line and deal directly with the
impedence of the dipole directly.

This analysis seems to imply use of the antenna on only one one band.

Ill conceived alternative feed arrangments are the most common reason
why so-called G5RVs performs even poorer than the "genuine" article.

The original question about how well "Euro zip line" will perform will
depend on the characteristics of the line. I hazard a guess that it
will be unlikely to have a characteristic impedance as low as 75 ohms
as suggested by some, more likely 100 ohms or more. It is likely to be
PVC insulated, and lines of that type perform much poorer than a high
z line made of the same conductor, not just because of the dielectric
issue, but because the RF resistance of the conductor increases as the
spacing is reduced for very close spacings (proximity effect).

As to whether it "works" for you, you need to define your criteria for
"works". If "works" means you make some QSOs, then I am sure it
"works", but if "works" meand you want to deliver 80% plus of the
transmitter power to the "G5RV variant" antenna feedpoint on several
bands, then it is unlikely to "work".

For arguments sake, if the feedpoint Z of a 30.5m centre fed dipole
(G5RV length) on 3.6MHz is 10-j340, using the characteristics of US
Zip cord measured by K8ZOA, the loss in 25m of such feeder would be
13dB with a Zin of 563-61, so there would be some small
(insignificant) additional tuner loss. Is this what you mean by
"works"?

Owen
--

"Hal Rosser" wrote in message
...


I think he was correct about the half-wave length of feedline:
according to the ARRL Antenna Book - 17th edition copyright 1994 -
page
24-12 in chapter 24, under the Heading "Special Cases" and under the
sub-heading "The Half-WaveLength Line", it pretty clearly states that
regardless of z, it will be the same on both ends of a half-wave line.
and
sections having such length can be added or removed without changing the
load Z. (as long as loss is negligible)

Also - You don't need to know the VF if you use a dip meter (or MFJ 259) -
And he would want the length to be half-wave so as to be able to ignore
the
characteristic impedence of the zip line and deal directly with the
impedence of the dipole directly.



Exactly

I also have a W6RCA type antenna up...80m dipole in the trees 25-50 feet,
fed by 98 feet of homemade 4" spaced ladder line, and ending outside the
shack wall with a way to add-in lengths of the feed line by 1 foot, 2 foot,
4 feet or 8 feet. This allows tuning the feedline onto any ham band almost
via harmonic relationship of the bands . You endup with a multiple halfwave
feedline and whatever swr the antenna runs shows up at the feedpoint (50
ferrite coax to ladder balun 1:1). Best antenna I have. Always better to
tune the feedline, and translate the antenna characteristic from the remote
locale to the shack wall. There is some loss I guess, but I cant detect it
or measure it, and I dont care because the antenna radiates and receives and
I get 59 reports.

Tim

Any body dealing with antennas in this group, what I read was pretty off
color and off subject. Want to know what a CCD antenna is really
supposed to do compared to say a delta loop...Just put one up and it
seems too good to be true compared to my well known hot signal 40 meter
delta...what is your opinion and please reply all so I will get a person
response. dont think Ill be reading this group everyday...who cares
about the british pound? EH? thanks Murray K5MDM

Richard Clark wrote:
On Tue, 12 Jul 2005 20:44:33 GMT, "pegge"
wrote:

someone tried to feed a type g5rv antenna with ´european´ zip-cord ?
Would yield a simple ant, peel the first say abt 15- 17 meters, splitting
them up to the dipole part and the the rest X meter to a balanced tuner etc.


Hi Per,

Hard to apply the name g5rv to this, but that makes no difference
anyway. Simply call it a dipole driven with close spaced twin lead.
That twin lead will be 50 to 70 Ohms characteristic impedance. It
will also have a suspect dielectric loss. This does not make it a bad
antenna. There will be the usual high loss with high SWR - depending
upon the gauge of the wire.

In short, no worse than an ordinary antenna used outside of its
natural resonance.

73's
Richard Clark, KB7QHC

On Thu, 14 Jul 2005 19:19:28 -0500, Murray wrote:

This is a multi-part message in MIME format.

This is still pretty obnoxious.

--------------010006030806060308030708
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit

Any body dealing with antennas in this group, what I read was pretty off
color and off subject.

Hi Murray,

It is called the price of admission, and is the exercise of American
rights to unrestrained speech.

Want to know what a CCD antenna is really
supposed to do compared to say a delta loop...Just put one up and it
seems too good to be true compared to my well known hot signal 40 meter
delta...what is your opinion and please reply all so I will get a person
response.

The CCD is one of those arm-chair designs that is a gift to mankind in
the form of gain from a dipole.

To being with, the theory behind it is that this antenna is frequency
specific, and that it is much larger than the standard dipole it
replaces. If this is news to you, then there's trouble ahead.

Continuing, the theory behind it maintains that each section is tuned
and presents a current maxima that aids with each of its neighbors to
thus increase gain. The standard current distribution along the
standard dipole is cosine shaped by and large. For the CCD it is
presumably linear - until you get to the ends of course where it
plummets to 0 in the last section. Myself, I respond to this
description of an antenna by parts as being much like a fresnel lens
in its conception.

However, modeling, such as I have done, fails to substantiate the
claims even if through contortions and exasperation I do manage to
attains some semblance of the linear current model.

Further, physical models bear out no particular boon to mankind that
has been extolled.

dont think Ill be reading this group everyday...who cares
about the british pound? EH?

This falls into the category of off topic response, something you
presumably eschew and simultaneously indulge in. This, too, is a
commonplace activity.

I am happy to respond to all topics that interest me. There are other
endlessly boring discussion of antennas - notably those that have
survived hurricanes as evidenced by photo doctoring - that remain on
topic, and off interest. I don't complain about it though, except to
recite as a parable.

73's
Richard Clark, KB7QHC

Want to know what a CCD antenna is really
supposed to do compared to say a delta loop...Just put one up and it
seems too good to be true compared to my well known hot signal 40 meter
delta...what is your opinion and please reply all so I will get a
person
response.

We already quickly talked about this a year or two ago, but
I'm not that great a fan of them. Or at least, I see no real advantage
to any other type of antenna. I've worked and check signals on scads
of those over the years, and to tell you the truth, as far as
performance
compared to just a dipole, they are often inferior in the real world.
Or to put it another way....Many of the CCD users often had inferior
signals compared to the dipole users, when you take an average
reading over a period of days or weeks.. I never saw any that were
better...
Why does it seem to good to be true? All a CDD does is supposably
maintain a more constant current distribution across the antenna.
In some cases, IE: a steep inv vee, this could be a *disadvantage*.
Or seems to me...I would prefer the current concentrated at the apex,
which is the high point of the antenna. If you spread current more
towards
lower sections of the wire, this could actually decrease perfomance.
Myself, I see no advantage, and will stick to my dipoles, etc...MK