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Carolina Windom without a balun: go figure



 
 
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  #1  
Old October 29th 08, 01:52 AM posted to rec.radio.amateur.antenna
jawod
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Posts: 303
Default Carolina Windom without a balun: go figure

Well, as an update to my Carolina Windom project, I find that the CW OCF
dipole cut to typical dimensions works well WITHOUT a balun but does not
work at all WITH a balun.

Specifically, a DX Engineering BAL200-H10-AT 4:1 balun. I bought it to
go with a folded dipole from DX Engineering. It worked fine with the
folded dipole and a length 300 Ohm ladder line as feed.

When I use the above balun with the CW cut to typical dimensions and
using a 300 ohm ladderline feed, even RECEIVE is muted...no change from
coax only.

I am fairly sure that the balun is a voltage type and not a choke type.
I also installed a series of ferrite beads from Palomar to choke the
coax near the bottom of the ladderline.

I guess I'm not all that surprised that the CW works without a
balun...the ATU tunes it and sig reports aren't bad. I guess I have
some radiation from coax and a mismatch from coax to ladderline but I
think I can live with that. It's getting cold and I needed to finish
this thing before winter really sets in.

I am clueless as to why the CW failed to work AT ALL when USING a balun.
The internals of the balun look fine.

Any thoughts?

(here goes)

John
AB8O
  #2  
Old October 29th 08, 06:24 AM posted to rec.radio.amateur.antenna
John Smith
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Posts: 2,915
Default Carolina Windom without a balun: go figure

jawod wrote:
Well, as an update to my Carolina Windom project, I find that the CW OCF
dipole cut to typical dimensions works well WITHOUT a balun but does not
work at all WITH a balun.

Specifically, a DX Engineering BAL200-H10-AT 4:1 balun. I bought it to
go with a folded dipole from DX Engineering. It worked fine with the
folded dipole and a length 300 Ohm ladder line as feed.

When I use the above balun with the CW cut to typical dimensions and
using a 300 ohm ladderline feed, even RECEIVE is muted...no change from
coax only.

I am fairly sure that the balun is a voltage type and not a choke type.
I also installed a series of ferrite beads from Palomar to choke the
coax near the bottom of the ladderline.

I guess I'm not all that surprised that the CW works without a
balun...the ATU tunes it and sig reports aren't bad. I guess I have
some radiation from coax and a mismatch from coax to ladderline but I
think I can live with that. It's getting cold and I needed to finish
this thing before winter really sets in.

I am clueless as to why the CW failed to work AT ALL when USING a balun.
The internals of the balun look fine.

Any thoughts?

(here goes)

John
AB8O



Hmmm ...

Cecil is the first one to even get me to try an OCF antenna! I thought
I like my life "balanced"; now, I find, I can go though live
"unbalanced" and "off center." grin

However, the 300 ohm line you are using IS balanced. So, I am assuming
you have a 50 ohm UNBALNCED output from your rig OR PA, and this is
where you would insert the 4:1 (6:1 would be better), and that you have
inserted it there, right? Properly, directly at the rigs output, to
engage the 300 ohm line, right? (i.e., between the rigs 50 ohm
UNBALANCED out and the 300 ohm balanced line?)

If you have it there, and did not notice an improvement, or at least no
change, we have another problem--apparently ...

Warm regards,
JS
  #3  
Old October 29th 08, 06:25 AM posted to rec.radio.amateur.antenna
John Smith
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Posts: 2,915
Default Carolina Windom without a balun: go figure

jawod wrote:
Well, as an update to my Carolina Windom project, I find that the CW OCF
dipole cut to typical dimensions works well WITHOUT a balun but does not
work at all WITH a balun.

Specifically, a DX Engineering BAL200-H10-AT 4:1 balun. I bought it to
go with a folded dipole from DX Engineering. It worked fine with the
folded dipole and a length 300 Ohm ladder line as feed.

When I use the above balun with the CW cut to typical dimensions and
using a 300 ohm ladderline feed, even RECEIVE is muted...no change from
coax only.

I am fairly sure that the balun is a voltage type and not a choke type.
I also installed a series of ferrite beads from Palomar to choke the
coax near the bottom of the ladderline.

I guess I'm not all that surprised that the CW works without a
balun...the ATU tunes it and sig reports aren't bad. I guess I have
some radiation from coax and a mismatch from coax to ladderline but I
think I can live with that. It's getting cold and I needed to finish
this thing before winter really sets in.

I am clueless as to why the CW failed to work AT ALL when USING a balun.
The internals of the balun look fine.

Any thoughts?

(here goes)

John
AB8O



Hmmm ...

Cecil is the first one to even get me to try an OCF antenna! I thought
I like my life "balanced"; now, I find, I can go though life
"unbalanced" and "off center." grin

However, the 300 ohm line you are using IS balanced. So, I am assuming
you have a 50 ohm UNBALNCED output from your rig OR PA, and this is
where you would insert the 4:1 (6:1 would be better), and that you have
inserted it there, right? Properly, directly at the rigs output, to
engage the 300 ohm line, right? (i.e., between the rigs 50 ohm
UNBALANCED out and the 300 ohm balanced line?)

If you have it there, and did not notice an improvement, or at least no
change, we have another problem--apparently ...

Warm regards,
JS
  #4  
Old October 29th 08, 06:42 AM posted to rec.radio.amateur.antenna
Owen Duffy
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Posts: 1,169
Default Carolina Windom without a balun: go figure

jawod wrote in
:

Well, as an update to my Carolina Windom project, I find that the CW
OCF dipole cut to typical dimensions works well WITHOUT a balun but
does not work at all WITH a balun.

Specifically, a DX Engineering BAL200-H10-AT 4:1 balun. I bought it
to go with a folded dipole from DX Engineering. It worked fine with
the folded dipole and a length 300 Ohm ladder line as feed.

When I use the above balun with the CW cut to typical dimensions and
using a 300 ohm ladderline feed, even RECEIVE is muted...no change
from coax only.

I am fairly sure that the balun is a voltage type and not a choke
type. I also installed a series of ferrite beads from Palomar to choke
the coax near the bottom of the ladderline.

I guess I'm not all that surprised that the CW works without a
balun...the ATU tunes it and sig reports aren't bad. I guess I have
some radiation from coax and a mismatch from coax to ladderline but I
think I can live with that. It's getting cold and I needed to finish
this thing before winter really sets in.

I am clueless as to why the CW failed to work AT ALL when USING a
balun. The internals of the balun look fine.

Any thoughts?


1. Doesn't the manufacturer of Carolina Windom's claim one of the
benefits is feed line radiation? (If you can't suppress it, call it out
as a competetive advantage?)

2. DX Engineering are a bit light on info on the balun, like most
manufacturers I guess... but the title bar of the web page says it is a
current balun. Pity the technical details tab doesn't make it clear.

3. If the design is intended to excite feed line common mode current,
then the device at the top of the feed line is probably a 4:1 Ruthroff
balun which has very low common mode impedance (differently to an
effective current balun).

4. What has 300 ohm line got to do with the Carolina Windom?

Owen
  #5  
Old October 29th 08, 12:24 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_]
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Posts: 3,522
Default Carolina Windom without a balun: go figure

jawod wrote:
I am clueless as to why the CW failed to work AT ALL when USING a balun.
The internals of the balun look fine. Any thoughts?


1. Baluns are designed for a narrow range of *resistive*
impedances, e.g. 50/200 ohms (plus or minus). Over what
range of impedances are you asking your balun to function
properly? Baluns don't handle massive reactance very well.

2. A misapplication example: 300 ohm twinlead with a 10:1
SWR can take the impedance seen by the balun down to 30 ohms.
Then the 4:1 balun tries to take 30 ohms down to 7.5 ohms.
That's a lossy situation for a tuner.
--
73, Cecil http://www.w5dxp.com
  #6  
Old October 29th 08, 04:10 PM posted to rec.radio.amateur.antenna
Michael Coslo
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Posts: 828
Default Carolina Windom without a balun: go figure

jawod wrote:
Well, as an update to my Carolina Windom project, I find that the CW OCF
dipole cut to typical dimensions works well WITHOUT a balun but does not
work at all WITH a balun.

Specifically, a DX Engineering BAL200-H10-AT 4:1 balun. I bought it to
go with a folded dipole from DX Engineering. It worked fine with the
folded dipole and a length 300 Ohm ladder line as feed.

When I use the above balun with the CW cut to typical dimensions and
using a 300 ohm ladderline feed, even RECEIVE is muted...no change from
coax only.

I am fairly sure that the balun is a voltage type and not a choke type.
I also installed a series of ferrite beads from Palomar to choke the
coax near the bottom of the ladderline.

I guess I'm not all that surprised that the CW works without a
balun...the ATU tunes it and sig reports aren't bad. I guess I have
some radiation from coax and a mismatch from coax to ladderline but I
think I can live with that. It's getting cold and I needed to finish
this thing before winter really sets in.

I am clueless as to why the CW failed to work AT ALL when USING a balun.
The internals of the balun look fine.



Hey John,

Trying to make sure that we are on the same page here.

You are using a OCF dipole with a 4:1 Balun, and using ladder line to go
from the balun to the shack?

Most of the OCF's I am familiar with run coax from the balun to the shack.

What are the respective leg lengths here? Height? Something is a little
askew here.

- 73 de Mike N3LI -

  #7  
Old October 29th 08, 04:14 PM posted to rec.radio.amateur.antenna
Michael Coslo
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Posts: 828
Default Carolina Windom without a balun: go figure

Owen Duffy wrote:

4. What has 300 ohm line got to do with the Carolina Windom?



True enough. I tried an OCF as a way to be able to run coax and have
multi band no-tuning and get rid of the window line.

Tried it, it was interresting, and now I'm back to using window line.


- 73 de Mike N3LI -
  #8  
Old October 29th 08, 05:48 PM posted to rec.radio.amateur.antenna
Ed Cregger
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Posts: 238
Default Carolina Windom without a balun: go figure


"Michael Coslo" wrote in message
...
Owen Duffy wrote:

4. What has 300 ohm line got to do with the Carolina Windom?



True enough. I tried an OCF as a way to be able to run coax and have multi
band no-tuning and get rid of the window line.

Tried it, it was interresting, and now I'm back to using window line.


- 73 de Mike N3LI -


------------

Yep, it only takes a few key ups to punch a hole in the dielectric in the
coax.

Ed, NM2K


  #9  
Old October 29th 08, 10:50 PM posted to rec.radio.amateur.antenna
jawod
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Posts: 303
Default Carolina Windom without a balun: go figure

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.

With the DX Engineering balun in place as in the figure, no xmit and no
rcv ... i.e., no diff than open-ended (shorted?) coax.

When I bypassed the balun and connected the balanced twin lead directly
to the coax...NOW I have good receive and pretty good sig reports.

Yes a 6:1 balun should also work according to what I've read.

The feedline radiation is intended for the 300 ohm twinlead only, not
the coax below the balun.

I am pretty sure the balun is the Ruthroff type that Owen mentions
(i.e., not a CHOKE balun)

I guess I'll conclude that the balun has failed. However, on inspection
the balun looks perfect...it is only 2 yrs old, has5 KW continuous power
rating and I run 40 W. Also, it worked perfectly well when used
originally with the DX Engineering folded dipole, also using a 300 ohm
feedline. (this is why I chose the CW...I had the stuff for it)

I appreciate the discussion

John
AB8O
  #10  
Old October 30th 08, 01:06 AM posted to rec.radio.amateur.antenna
Owen Duffy
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Posts: 1,169
Default Carolina Windom without a balun: go figure

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
 




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