Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #11   Report Post  
Old October 30th 08, 03:18 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 303
Default Carolina Windom without a balun: go figure

Owen Duffy wrote:
jawod wrote in :


I've attached the original article that describes the CW in question.



As you now know, that didn't work.

You need to put the article on a web site somewhere, or give the URL of an
existing copy.

Owen

Thank you SO much Owen

here ya go

www.w5fc.org/files/QRP%20Expressions.pdf

John
AB8O
  #12   Report Post  
Old October 30th 08, 03:52 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Mar 2007
Posts: 46
Default Carolina Windom without a balun: go figure

On Wed, 29 Oct 2008, jawod wrote:

here ya go

www.w5fc.org/files/QRP%20Expressions.pdf

John
AB8O


This was the article that convinced me to build a NCW. (The 3rd option)
I scaled mine up to the 132 ft version so I could have 80m.

When I finally have a QTH to support its size, I will string it up
permanently. Till then, it is my field-day antenna of choice.

My 706IIg with AT180 autotuner have no trouble getting a clean match on 6m
thru 80m.


  #13   Report Post  
Old October 30th 08, 05:03 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Carolina Windom without a balun: go figure

jawod wrote in :

....
Thank you SO much Owen

here ya go

www.w5fc.org/files/QRP%20Expressions.pdf


There are a host of issues with the content of the article. I don't
intend to red pen the article, but the issues sound a warning about
credibility.

There is no doubt it describes a Ruthroff 4:1 balun in its "new Carolina
Windom" configuration. Such a balun will have a very low common mode
impedance.

Factors of your implementation that are / may be different include:

The DXE balun you used appears to be described as a current balun on the
DXE web site. If it is, it may work differently. (I have already
commented on the lack of clarity of the product information, perhaps they
might clarify it if you email them with a support question - "what did I
buy?".)

DXE also warn us that 'tuner' style baluns such as the one you used are
more likely to be reactive an higher frequencies... presumably a
consequence of thicker wire insulation which increases the Zo of the TL
sections which results in less ideal impedance transformation with
increasing frequency.

Owen
  #14   Report Post  
Old October 30th 08, 05:26 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 303
Default Carolina Windom without a balun: go figure


DXE also warn us that 'tuner' style baluns such as the one you used are
more likely to be reactive an higher frequencies... presumably a
consequence of thicker wire insulation which increases the Zo of the TL
sections which results in less ideal impedance transformation with
increasing frequency.



Thanks for the input. The strange thing is that the system failed at
ALL freq's. The original use of the balun was with a folded dipole and
a feedline of 300 ohm twinlead cut to an odd multiple of the lowest freq
desired...which I did and it worked reasonably well. I cannot
understand how this application (the CW OCF) is significantly different
from the original one, at least in terms of using a 4:1 balun.

Allow me to put this to rest. I can live with it as it is, theoretical
considerations notwithstanding. I don't want to go over to the dark
side, but, hey, it works. Maybe I have a new "Magic" Antenna.

John
AB8O
  #15   Report Post  
Old October 30th 08, 05:40 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Carolina Windom without a balun: go figure

jawod wrote in :
... Maybe I have a new "Magic" Antenna.


Instead of the "perfect antenna" as claimed in the article!

Owen


  #16   Report Post  
Old October 30th 08, 12:46 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Carolina Windom without a balun: go figure

jawod wrote:
Three versions of the Carolina Windom are presented:
Original single wire feed,


Actually, not a Carolina Windom - simply a traditional
Windom, the grandfather of all Windoms - named after
Major General Loren G. Windom, W8GZ, (Windy) (QST,
Sep 1929, pp 19-22, 84).

www.geocities.com/w8jyz/8GZ.pdf

OCF with twinlead and balun,


Don't know if it was ever a commercially available
antenna called a "Carolina Windom" but this is just a
traditional "Off-Center-Fed Dipole" labeled as such in
my 1957 ARRL Handbook.

http://www.w8ji.com/windom_off_center_fed.htm

and OCF with 10' length of coax


This is what most people think about when someone says
"Carolina Windom" and the reason that some people were
confused.

http://www.hamuniverse.com/k4iwlnewwindom.html

I guess I'll conclude that the balun has failed.


At least hang a 200 ohm non-inductive resistor on the
output and measure the input impedance. I don't know
how you can assume the balun has failed if you don't
know what impedances the balun was having to deal with.
--
73, Cecil http://www.w5dxp.com
  #17   Report Post  
Old October 30th 08, 03:45 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Mar 2007
Posts: 17
Default Carolina Windom without a balun: go figure

On 2008-10-29, jawod wrote:
I've attached the original article that describes the CW in question.
Three versions of the Carolina Windom are presented: Original single
wire feed, OCF with twinlead and balun, and OCF with 10' length of coax
to a choke balun (1:1). Mine is the middle one. Please see Fig 3A. The
balun is at the bottom of the twin lead (I think I mistakenly referred
to it as ladder line). I added large ferrite beads just below the balun
on the coax as discussed here in the group earlier.


If I'm reading this correctly, you put the balun at the bottom of the twin
lead and the ferrite bead balun just under it.

Many 'Carolina Windoms' use the balun at the feed point, the ladder line or
twin lead under that, and the ferrite bead balun at the bottom of the ladder
line, to which is attached the coax.

Placing the balun (4:1 or whatever) under the twin lead would really do
strange things to the impedance and probably cause the problems you mentioned.

73 ...Edwin, KD5ZLB
--
__________________________________________________ __________
"Once you have flown, you will walk the earth with your eyes
turned skyward, for there you have been, there you long to
return."-da Vinci http://bellsouthpwp2.net/e/d/edwinljohnson
  #18   Report Post  
Old October 30th 08, 06:04 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jun 2006
Posts: 1,374
Default Carolina Windom without a balun: go figure

When trying to understand off center fed antennas, it's important to
realize a few key facts:

1. A properly working "voltage" or "Ruthroff" balun will force common
mode current to exist on the feedline in its attempt to cause equal
voltages on the unequal length sides relative to the feedline shield.
2. Even if an effective "current" or "Guanella" balun is used, feedline
current will still be induced by the uneven coupling between the two
antenna sides.
3. A transforming balun is very unlikely to effect the expected
transformation ratio, and is likely to add a significant amount of
series and/or shunt reactance except at those spot frequencies where the
match is close to perfect.

This isn't to say that off center fed antennas can't sometimes be made
to "work", i.e., provide a reasonable impedance match on some bands. But
when they do, it's not for the reasons you think from an analysis
assuming a perfect transformer and balun. It usually involves a complex
relationship among the particular imperfections of the
balun/transformer, feedline, and path to the Earth taken by the feedline
shield.

Roy Lewallen, W7EL
  #19   Report Post  
Old October 30th 08, 06:34 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Oct 2008
Posts: 1
Default Carolina Windom without a balun: go figure

Edwin Johnson wrote:

...
Placing the balun (4:1 or whatever) under the twin lead would really do
strange things to the impedance and probably cause the problems you mentioned.

73 ...Edwin, KD5ZLB


Actually, I would expect placing a 4:1 balun under the 300 ohm balanced
line and before the 50 ohm unbalanced to provide a step-up(or step-down,
depending on the "direction" you view it from) of 50:200 or 4:1, as it
properly should. However, as someone presented in a paper a little
while back, some antennas "filled with errors" are able to function in
some manner and end up gaining their supporters ...

If you were to place a 1:1 balun at this same point, I would expect
little difference, but a difference (and, since you are mismatched at
this point, simply maintaining this mismatch with a component
introducing some loss and "redirecting" CM currents, not a good difference!)

It seems the "misunderstood/mystical/magical balun" lives on ...

Regards,
JS
  #20   Report Post  
Old October 30th 08, 09:38 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Carolina Windom without a balun: go figure

Roy Lewallen wrote in
treetonline:

When trying to understand off center fed antennas, it's important to
realize a few key facts:

....

Yes, I thing you are quite correct Roy.

The advertising hype that goes along with many of these commercially
popularised antennas gives the impression that deployment of multi-band
wire antennas for the lower HF bands is a very standardised thing, a no-
brainer. One buys the product, installs it in their own environment in
their own way, and it just "works" out of the box... whatever "works"
means.

The real world doesn't work that simply.

But to a buyer with faith in the promotional claims, they can buy a lot
of satisfaction for only $69.99 or whatever, and not have any untidy left
over materials to clutter up their home, or residual technical issues to
clutter up their mind.

Today, the growth opportunity in the US is selling attic antennas for low
HF bands to new hams. Not as popular here because restrictive covenants
on residential properties aren't as common.

But, hey, a simple wire antenna with published performance figures from
160m to 2m is attractive to *our* new six hour hams. Which antenna is
that? The W5GI Mystery Antenna, you know, the one "that performs
exceptionally well even though it confounds antenna modeling software".

Owen
Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Carolina Windom revisited: 4 to 1 balun does nothing to choke RF? john Wiener Antenna 20 September 24th 08 04:14 PM
Carolina Windom using 300 ohm ladderline john Wiener Antenna 10 September 11th 08 04:02 PM
FS: Carolina Windom 75 Meter Ant Tim Neff Swap 2 April 30th 06 02:39 PM
FA: Carolina Windom 160M Larry Wilson Swap 0 June 10th 05 09:31 PM
Carolina Windom jimbo Antenna 9 March 16th 05 02:38 PM


All times are GMT +1. The time now is 03:27 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017