No buck, the line is always longer than 1/2 wave. It is a matching section
from what is at the antenna to 50 ohms, and then 1/2 wave from that point.

"Buck" wrote in message
...
Pardon me while I learn from this discussion.

The 450 ohm antenna is designed to be tuned by using exactly 1/2
electrical wave lengths to match both the transmitter and antenna.
This should mean that any differing feedline should work equally as
well (except for the losses) if I am correct....




On Tue, 7 Jun 2005 18:02:43 -0400, "Fred W4JLE"
wrote:

I feed it with an electrical 1/2 wave length of exactly 450 Ohm feedline.
The 50 Ohms from my antenna is repeated at the other end of the feedline.
An
SWR bridge calibrated for 50 Ohms and my rig see 1:1.

--
73 for now
Buck
N4PGW

Did you miss the tuner part? The "magic antenna" is the same all band sold
by a number of folks, i.e. Van Gordon.

..

"Wes Stewart" wrote in message
...
On Wed, 08 Jun 2005 12:52:01 -0400, Buck wrote:

Pardon me while I learn from this discussion.

Hold on Buck.

So far there has been very little "learning" to be done from this
discussion.

I dislike getting personal but I strongly suggest that you reject
anything Fred has put forth. Some of what he says is correct, but for
the most part you are being led astray. Since you don't yet have the
skills to separate the good from the BS, the safest thing to do is
ignore it all.

On Wed, 08 Jun 2005 20:41:58 -0500, Cecil Moore
wrote:

Buck wrote:
Pardon me while I learn from this discussion.

What you are missing is that first piece of matching section
which can be any length less than 1/2WL. After that first
piece of matching section, you could indeed switch to a
different characteristic impedance. Congratulations, you
have just invented the G5RV. :-)


Hmmm, and I'm not even british.....



The G5RV is a twenty meter antenna, isn't it? It needs a tuner on all
other bands if I am not mistaken.

--
73 for now
Buck
N4PGW

Buck wrote:
The G5RV is a twenty meter antenna, isn't it? It needs a tuner on all
other bands if I am not mistaken.

The G5RV needs a tuner on all bands. Acceptable SWRs are
very rare without a tuner. The G5RV is 1.5WL long on
20m. The resonant feedpoint impedance on 20m is in excess
of 100 ohms giving a 50 ohm SWR in excess of 2:1 so a
tuner is required, even on 20m. However, I have done to
a G5RV what Fred has done to a 1/2WL 80m dipole. The
matching section on my G5RV is a variable length between
22' and 38'. My G5RV has an SWR below 1.5:1 on all eight
HF bands. I'm going to write it up one of these days.
--
73, Cecil http://www.qsl.net/w5dxp

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I am a little confused, so bare with me.....

I put up an antenna with 50 ohm of impedance. I feed it with any
length of 300 ohm feed less than 1/2 L. Then I run 1/2 L of 50 ohm
feed to the radio and I have the 50 ohm match?

similar:

I put up a 300 ohm antenna. I feed it with 300 ohm twin lead for less
than 1/2 L and 1/2 L of 50 ohm feedline. Is this a 50 ohm match?

(L=Lamda)

Thanks
Buck





On Thu, 9 Jun 2005 00:27:26 -0400, "Fred W4JLE"
wrote:

No buck, the line is always longer than 1/2 wave. It is a matching section
from what is at the antenna to 50 ohms, and then 1/2 wave from that point.

"Buck" wrote in message
.. .
Pardon me while I learn from this discussion.

The 450 ohm antenna is designed to be tuned by using exactly 1/2
electrical wave lengths to match both the transmitter and antenna.
This should mean that any differing feedline should work equally as
well (except for the losses) if I am correct....




On Tue, 7 Jun 2005 18:02:43 -0400, "Fred W4JLE"
wrote:

I feed it with an electrical 1/2 wave length of exactly 450 Ohm feedline.
The 50 Ohms from my antenna is repeated at the other end of the feedline.
An
SWR bridge calibrated for 50 Ohms and my rig see 1:1.

--
73 for now
Buck
N4PGW


--
73 for now
Buck
N4PGW

On Thu, 09 Jun 2005 11:16:38 -0400, Buck Naked wrote:

I am a little confused, so bare with me.....

I'm not about to get naked with you, but you are more than a little
confused.

You have listened to too much bafflegab in this thread.

I showed you in detail how to answer your own questions. Did you not
read my post?

Buck wrote:
I am a little confused, so bare with me.....

I put up an antenna with 50 ohm of impedance. I feed it with any
length of 300 ohm feed less than 1/2 L. Then I run 1/2 L of 50 ohm
feed to the radio and I have the 50 ohm match?

Nope, 50 ohms is only one of an infinite number of impedances
you might encounter. For 50 ohms, you feed it with 1/2WL of
300 ohm feedline. This is similar to (but not exactly like)
a G5RV used on 20m.

I put up a 300 ohm antenna. I feed it with 300 ohm twin lead for less
than 1/2 L and 1/2 L of 50 ohm feedline. Is this a 50 ohm match?

Nope, you cannot transform the impedance of a 300 ohm antenna
using 300 ohm feedline. You need reflections to cause an
impedance transformation. A 300 ohm antenna impedance is
not within the green doughnut area below.

The range of impedances that can be matched with a length of
450 ohm ladder-line are represented by the green doughnut at:

http://www.qsl.net/w5dxp/smith.htm

The impedances outside the green area cannot be matched by
only one 450 ohm matching section. The area in the doughnut
hole cannot be matched by only one 450 ohm matching section.
--
73, Cecil, http://www.qsl.net/w5dxp


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On Thu, 09 Jun 2005 11:38:22 -0500, Cecil Moore
wrote:

Buck wrote:
I am a little confused, so bare with me.....

I put up an antenna with 50 ohm of impedance. I feed it with any
length of 300 ohm feed less than 1/2 L. Then I run 1/2 L of 50 ohm
feed to the radio and I have the 50 ohm match?

Nope, 50 ohms is only one of an infinite number of impedances
you might encounter. For 50 ohms, you feed it with 1/2WL of
300 ohm feedline. This is similar to (but not exactly like)
a G5RV used on 20m.

I put up a 300 ohm antenna. I feed it with 300 ohm twin lead for less
than 1/2 L and 1/2 L of 50 ohm feedline. Is this a 50 ohm match?

Nope, you cannot transform the impedance of a 300 ohm antenna
using 300 ohm feedline. You need reflections to cause an
impedance transformation. A 300 ohm antenna impedance is
not within the green doughnut area below.

The range of impedances that can be matched with a length of
450 ohm ladder-line are represented by the green doughnut at:

http://www.qsl.net/w5dxp/smith.htm

The impedances outside the green area cannot be matched by
only one 450 ohm matching section. The area in the doughnut
hole cannot be matched by only one 450 ohm matching section.


When I click on your links, I get connection refused from qsl.net

--
73 for now
Buck
N4PGW

Buck wrote:
When I click on your links, I get connection refused from qsl.net

qsl.net is not very fast or reliable. I just tried it
and was refused. Maybe too many present users. Try
again later.
--
73, Cecil, http://www.qsl.net/w5dxp


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You can't match a 300 ohm antenna with 300 ohm line. A matching section
relies on SWR (read reflections) to match.

once matched, any impeadence feed line may be used from the matched point as
long as it is an electrical half wavelength or multiple at the frequency of
interest.

The only difference will be the SWR on the line. Your rig would still see
the SWR ar the match point.

Given an antenna that has 50 Ohms +J0, feed it with 50 ohm line and the swr
for the system is 1:1, substitute a 1/2 wave of 450 ohm line and the antenna
and the rig are both at 50 ohms. The SWR on the feedline is 450/50 or 9:1.

Look at the half wave of feedline as two back to back 1/4 wave matching
sections. The SWR on the feedline is of no consequece as the losses are so
low as not to have a practical effect.


"Buck" wrote in message
...
I am a little confused, so bare with me.....

I put up an antenna with 50 ohm of impedance. I feed it with any
length of 300 ohm feed less than 1/2 L. Then I run 1/2 L of 50 ohm
feed to the radio and I have the 50 ohm match?

similar:

I put up a 300 ohm antenna. I feed it with 300 ohm twin lead for less
than 1/2 L and 1/2 L of 50 ohm feedline. Is this a 50 ohm match?

(L=Lamda)

Thanks
Buck





On Thu, 9 Jun 2005 00:27:26 -0400, "Fred W4JLE"
wrote:

No buck, the line is always longer than 1/2 wave. It is a matching
section
from what is at the antenna to 50 ohms, and then 1/2 wave from that
point.

"Buck" wrote in message
.. .
Pardon me while I learn from this discussion.

The 450 ohm antenna is designed to be tuned by using exactly 1/2
electrical wave lengths to match both the transmitter and antenna.
This should mean that any differing feedline should work equally as
well (except for the losses) if I am correct....




On Tue, 7 Jun 2005 18:02:43 -0400, "Fred W4JLE"
wrote:

I feed it with an electrical 1/2 wave length of exactly 450 Ohm
feedline.
The 50 Ohms from my antenna is repeated at the other end of the
feedline.
An
SWR bridge calibrated for 50 Ohms and my rig see 1:1.

--
73 for now
Buck
N4PGW


--
73 for now
Buck
N4PGW