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ladderline and balun question

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KD8NNU

ladderline and balun question

Gents,

I have a ladder line and balun question that I hope someone can guide me
thru.

I had a good working antenna system with two antennas. First being an
Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
the air strung in trees. So the wire does touch the trees.

Dipole is fed with coax and choked at the feed point and the loop was
fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax to
the shack tuner. Then the amp and radio. This combination was working
real well no RF problems in the shack.

I was advised that I would obtain better results for better SWR at
resonance and easier matching if I removed the 1:1 balun and went to a
4:1 balun. I made this change with everything else being the same. I
now had RF in the shack again.

I then added an isolation balun to the system by adding 6ft coax from
the output of the 4:1 to a balun designs 116du which is supposed to have
4500 ohms of choking impedance on 160m and over 5000 ohms choking
impedance on 80 and 40 meters. This did not eliminate the RF and I am
still having problems.

So here is the question, is it possible that with the combination of
length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I am
at a feed line length that will be a problem no matter what I do. I
keep looking at the internet to try and figure this out but I am
confused as some information I find says it only applies to 1:1 baluns
or other factors.

So anyone who can help me understand this feed line question I will be
greatly appreciative.

Thanks
Don

~73
Don
KD8NNU

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Re: ladderline and balun question

Don, when it comes to ladder lines and baluns the only real expert was Jerry Sevick and he has gone to a better place where they only use resonant beam antennas. Take anything anyone is living says about open wire feeders and baluns with a grain of salt. Put your antenna back like it was when it worked. Ignore further advice from the living. Since I am still living, more or less, feel free to ignore this advice as well!

Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

________________________________
From: "[hidden email]" <[hidden email]>
To: [hidden email]
Sent: Wednesday, January 11, 2012 3:12 PM
Subject: [Elecraft] ladderline and balun question

Gents,

I have a ladder line and balun question that I hope someone can guide me
thru.

I had a good working antenna system with two antennas. First being an
Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
the air strung in trees. So the wire does touch the trees.

Dipole is fed with coax and choked at the feed point and the loop was
fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax to
the shack tuner. Then the amp and radio. This combination was working
real well no RF problems in the shack.

I was advised that I would obtain better results for better SWR at
resonance and easier matching if I removed the 1:1 balun and went to a
4:1 balun. I made this change with everything else being the same. I
now had RF in the shack again.

I then added an isolation balun to the system by adding 6ft coax from
the output of the 4:1 to a balun designs 116du which is supposed to have
4500 ohms of choking impedance on 160m and over 5000 ohms choking
impedance on 80 and 40 meters. This did not eliminate the RF and I am
still having problems.

So here is the question, is it possible that with the combination of
length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I am
at a feed line length that will be a problem no matter what I do. I
keep looking at the internet to try and figure this out but I am
confused as some information I find says it only applies to 1:1 baluns
or other factors.

So anyone who can help me understand this feed line question I will be
greatly appreciative.

Thanks
Don

~73
Don
KD8NNU

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Don Wilhelm-4

Re: ladderline and balun question

In reply to this post by KD8NNU

Don,

According to L B Cebik's modeling, a 2 wavelength horizontal loop will
have a feedpoint impedance of 180 - j125 ohms, and a 4 wavelength loop
(the same loop used on 80 meters will have a feedpoint impedance of 235
- j135.
Both are good candidates for the use of a 4:1 balun - but that only
applies if you mount the balun right at the antenna feedpoint. The fact
that you have 60 feet of 450 ohm feedline changes the situation
drastically - that is about 1/8 wavelength on 160 and close to 1/4
wavelength on 80 - so the feedoint impedance at the end of that 60 feet
of feedline is quite a bit lower - that is most likely why your 1:1
balun worked so well. You can work with L B Cebik's antenna feedpoint
impedances and the TLW application available from the ARRL to find the
feedpoint impedance at the end of the 60 foot feedline, but I think you
will find it closer to 50 ohms than to 200 ohms.

The other question is what type of balun is your 4:1 balun - if it is a
voltage type, it has no chance of stopping common mode current.

My guess for why your current choke did not work is either that you did
not place it at the right point on the coax, or it was at a point where
the RF voltage was high, and in light of a high RF voltage (think
impedance equal to 2000 to 4000 ohms, a choke of 5000 ohms impedance
does not have much of a chance to stop any current.

So bottom line - go back to what you had before, or put the 4:1 balun at
the antenna feedpoint where it should work if your antenna is anything
like L B Cebik's simulations.

73,
Don W3FPR

On 1/11/2012 4:12 PM, [hidden email] wrote:

> Gents,
>
> I have a ladder line and balun question that I hope someone can guide me
> thru.
>
> I had a good working antenna system with two antennas. First being an
> Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
> the air strung in trees. So the wire does touch the trees.
>
> Dipole is fed with coax and choked at the feed point and the loop was
> fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax to
> the shack tuner. Then the amp and radio. This combination was working
> real well no RF problems in the shack.
>
> I was advised that I would obtain better results for better SWR at
> resonance and easier matching if I removed the 1:1 balun and went to a
> 4:1 balun. I made this change with everything else being the same. I
> now had RF in the shack again.
>
> I then added an isolation balun to the system by adding 6ft coax from
> the output of the 4:1 to a balun designs 116du which is supposed to have
> 4500 ohms of choking impedance on 160m and over 5000 ohms choking
> impedance on 80 and 40 meters. This did not eliminate the RF and I am
> still having problems.
>
> So here is the question, is it possible that with the combination of
> length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I am
> at a feed line length that will be a problem no matter what I do. I
> keep looking at the internet to try and figure this out but I am
> confused as some information I find says it only applies to 1:1 baluns
> or other factors.
>
> So anyone who can help me understand this feed line question I will be
> greatly appreciative.
>
>

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Post: mailto:[hidden email]

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KD8NNU

Re: ladderline and balun question

In reply to this post by KD8NNU

HI Don,

I wish to look into the TLW application you mention. However, I am not
what it is exactly. Would you please be so kind as to point me in the
proper direction.

I most likely will be going back to the 1:1 balun but the promise of swr
of 1.3 on 160m was nice, which I have on the 4:1. Also it is a current
balun.

Thanks

~73
Don
KD8NNU

On Wed, Jan 11, 2012 at 5:02 PM, Don Wilhelm wrote:

> Don,
>
> According to L B Cebik's modeling, a 2 wavelength horizontal loop will
> have a feedpoint impedance of 180 - j125 ohms, and a 4 wavelength loop
> (the same loop used on 80 meters will have a feedpoint impedance of
> 235 - j135.
> Both are good candidates for the use of a 4:1 balun - but that only
> applies if you mount the balun right at the antenna feedpoint. The
> fact that you have 60 feet of 450 ohm feedline changes the situation
> drastically - that is about 1/8 wavelength on 160 and close to 1/4
> wavelength on 80 - so the feedoint impedance at the end of that 60
> feet of feedline is quite a bit lower - that is most likely why your
> 1:1 balun worked so well. You can work with L B Cebik's antenna
> feedpoint impedances and the TLW application available from the ARRL
> to find the feedpoint impedance at the end of the 60 foot feedline,
> but I think you will find it closer to 50 ohms than to 200 ohms.
>
> The other question is what type of balun is your 4:1 balun - if it is
> a voltage type, it has no chance of stopping common mode current.
>
> My guess for why your current choke did not work is either that you
> did not place it at the right point on the coax, or it was at a point
> where the RF voltage was high, and in light of a high RF voltage
> (think impedance equal to 2000 to 4000 ohms, a choke of 5000 ohms
> impedance does not have much of a chance to stop any current.
>
> So bottom line - go back to what you had before, or put the 4:1 balun
> at the antenna feedpoint where it should work if your antenna is
> anything like L B Cebik's simulations.
>
> 73,
> Don W3FPR
>
> On 1/11/2012 4:12 PM, [hidden email] wrote:
>> Gents,
>>
>> I have a ladder line and balun question that I hope someone can guide
>> me
>> thru.
>>
>> I had a good working antenna system with two antennas. First being
>> an
>> Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
>> the air strung in trees. So the wire does touch the trees.
>>
>> Dipole is fed with coax and choked at the feed point and the loop was
>> fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax
>> to
>> the shack tuner. Then the amp and radio. This combination was
>> working
>> real well no RF problems in the shack.
>>
>> I was advised that I would obtain better results for better SWR at
>> resonance and easier matching if I removed the 1:1 balun and went to
>> a
>> 4:1 balun. I made this change with everything else being the same.
>> I
>> now had RF in the shack again.
>>
>> I then added an isolation balun to the system by adding 6ft coax from
>> the output of the 4:1 to a balun designs 116du which is supposed to
>> have
>> 4500 ohms of choking impedance on 160m and over 5000 ohms choking
>> impedance on 80 and 40 meters. This did not eliminate the RF and I
>> am
>> still having problems.
>>
>> So here is the question, is it possible that with the combination of
>> length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I
>> am
>> at a feed line length that will be a problem no matter what I do.
>> I
>> keep looking at the internet to try and figure this out but I am
>> confused as some information I find says it only applies to 1:1
>> baluns
>> or other factors.
>>
>> So anyone who can help me understand this feed line question I will
>> be
>> greatly appreciative.
>>
>>

Don Wilhelm-4

Re: ladderline and balun question

Don,

If you don't have TLW, you might have to invest in the ARRL Antenna Book
- it is on the CD that comes with that book.
It is "Transmission Line for Windows", and you can plug in the antenna
feedpoint impedance, the type and length of feedline and the program
tells you the impedance at the other end.

73,
Don W3FPR

On 1/11/2012 5:11 PM, [hidden email] wrote:

> HI Don,
>
> I wish to look into the TLW application you mention. However, I am not
> what it is exactly. Would you please be so kind as to point me in the
> proper direction.
>
> I most likely will be going back to the 1:1 balun but the promise of swr
> of 1.3 on 160m was nice, which I have on the 4:1. Also it is a current
> balun.
>
> Thanks
>
> ~73
> Don
> KD8NNU
>
>
> On Wed, Jan 11, 2012 at 5:02 PM, Don Wilhelm wrote:
>
>> Don,
>>
>> According to L B Cebik's modeling, a 2 wavelength horizontal loop will
>> have a feedpoint impedance of 180 - j125 ohms, and a 4 wavelength loop
>> (the same loop used on 80 meters will have a feedpoint impedance of
>> 235 - j135.
>> Both are good candidates for the use of a 4:1 balun - but that only
>> applies if you mount the balun right at the antenna feedpoint. The
>> fact that you have 60 feet of 450 ohm feedline changes the situation
>> drastically - that is about 1/8 wavelength on 160 and close to 1/4
>> wavelength on 80 - so the feedoint impedance at the end of that 60
>> feet of feedline is quite a bit lower - that is most likely why your
>> 1:1 balun worked so well. You can work with L B Cebik's antenna
>> feedpoint impedances and the TLW application available from the ARRL
>> to find the feedpoint impedance at the end of the 60 foot feedline,
>> but I think you will find it closer to 50 ohms than to 200 ohms.
>>
>> The other question is what type of balun is your 4:1 balun - if it is
>> a voltage type, it has no chance of stopping common mode current.
>>
>> My guess for why your current choke did not work is either that you
>> did not place it at the right point on the coax, or it was at a point
>> where the RF voltage was high, and in light of a high RF voltage
>> (think impedance equal to 2000 to 4000 ohms, a choke of 5000 ohms
>> impedance does not have much of a chance to stop any current.
>>
>> So bottom line - go back to what you had before, or put the 4:1 balun
>> at the antenna feedpoint where it should work if your antenna is
>> anything like L B Cebik's simulations.
>>
>> 73,
>> Don W3FPR
>>
>> On 1/11/2012 4:12 PM, [hidden email] wrote:
>>> Gents,
>>>
>>> I have a ladder line and balun question that I hope someone can guide
>>> me
>>> thru.
>>>
>>> I had a good working antenna system with two antennas. First being
>>> an
>>> Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
>>> the air strung in trees. So the wire does touch the trees.
>>>
>>> Dipole is fed with coax and choked at the feed point and the loop was
>>> fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax
>>> to
>>> the shack tuner. Then the amp and radio. This combination was
>>> working
>>> real well no RF problems in the shack.
>>>
>>> I was advised that I would obtain better results for better SWR at
>>> resonance and easier matching if I removed the 1:1 balun and went to
>>> a
>>> 4:1 balun. I made this change with everything else being the same.
>>> I
>>> now had RF in the shack again.
>>>
>>> I then added an isolation balun to the system by adding 6ft coax from
>>> the output of the 4:1 to a balun designs 116du which is supposed to
>>> have
>>> 4500 ohms of choking impedance on 160m and over 5000 ohms choking
>>> impedance on 80 and 40 meters. This did not eliminate the RF and I
>>> am
>>> still having problems.
>>>
>>> So here is the question, is it possible that with the combination of
>>> length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I
>>> am
>>> at a feed line length that will be a problem no matter what I do.
>>> I
>>> keep looking at the internet to try and figure this out but I am
>>> confused as some information I find says it only applies to 1:1
>>> baluns
>>> or other factors.
>>>
>>> So anyone who can help me understand this feed line question I will
>>> be
>>> greatly appreciative.
>>>
>>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Re: ladderline and balun question

In reply to this post by KD8NNU

Don, no one has that knowledge to share because every piece of any material in the area of the antenna and feed lines affects the impedance and efficiency of the unit. No calculation simple enough to be handled by our computers and programs and within our ability to simulate is accurate enough to be sure. You can either blindly experiment as you have done and stop when you get acceptable results or you can buy the best antenna analyzer that you can afford and measure the result from your try. This method will probably not be accurate enough to get it right the first time, but will help you zero in on a good result. The ambiguous definition of "good result" is open to individual preference.

Unfortunately, most who experiment with wire loop antennas do so in search of a low cost, all band, universally low SWR antenna which will perform with the high tower mounted, directive, resonant arrays. This is not possible! Even if you strike low cost from the list! The reason that all the big gun contest stations have a money is no object approach is that it is the only way to produce world class results.

But wire antennas and open wire feeders are interesting and fun to experiment with. Hams have been looking for this cook book answer starting with Marconi. Some have had many an interesting QSO on this type of antenna, but the easy cook-book solution that can be explained in 100,000 words or less has not yet been discovered.

Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

________________________________
From: "[hidden email]" <[hidden email]>
To: WILLIS COOKE <[hidden email]>
Sent: Wednesday, January 11, 2012 4:05 PM
Subject: Re: [Elecraft] ladderline and balun question

HI Will,

That is reasonable advice, to just go back and that is definatly in the plans. However, before I climb up on ladders and so on I want to learn more in case I have a feed line length issue.

I can add more ladder line but I want a way to see if there is the possibility for success not just throw a different length at it.   I also am wondering if the 4:1 balun causes excessive imbalance so again hoping someone with more knowledge can help me out.

All I know is that this is the friendlest and most helpful list that I am a member of because of the quality of Hams that use elecraft equipment so I am hoping that there is some knowledge to share.

Thanks
Don

~73
Don
KD8NNU

On Wed, Jan 11, 2012 at 4:46 PM, WILLIS COOKE wrote:

Don, when it comes to ladder lines and baluns the only real expert was Jerry Sevick and he has gone to a better place where they only use resonant beam antennas. Take anything anyone is living says about open wire feeders and baluns with a grain of salt. Put your antenna back like it was when it worked. Ignore further advice from the living. Since I am still living, more or less, feel free to ignore this advice as well!

Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

___________________________________

From: "[hidden email]" <[hidden email]>
To: [hidden email]
Sent: Wednesday, January 11, 2012 3:12 PM
Subject: [Elecraft] ladderline and balun question

Gents,

I have a ladder line and balun question that I hope someone can guide me
thru.

I had a good working antenna system with two antennas. First being an
Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
the air strung in trees. So the wire does touch the trees.

Dipole is fed with coax and choked at the feed point and the loop was
fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax to
the shack tuner. Then the amp and radio.   This combination was working
real well no RF problems in the shack.

I was advised that I would obtain better results for better SWR at
resonance and easier matching if I removed the 1:1 balun and went to a
4:1 balun. I made this change with everything else being the same. I
now had RF in the shack again.

I then added an isolation balun to the system by adding 6ft coax from
the output of the 4:1 to a balun designs 116du which is supposed to have
4500 ohms of choking impedance on 160m and over 5000 ohms choking
impedance on 80 and 40 meters.   This did not eliminate the RF and I am
still having problems.

So here is the question, is it possible that with the combination of
length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I am
at a feed line length that will be a problem no matter what I do.    I
keep looking at the internet to try and figure this out but I am
confused as some information I find says it only applies to 1:1 baluns
or other factors.

So anyone who can help me understand this feed line question I will be
greatly appreciative.

Thanks
Don

~73
Don
KD8NNU

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto: [hidden email]

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Please help support this email list: http://www.qsl.net/donate.html
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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N5GE

Re: ladderline and balun question

In reply to this post by KD8NNU

Now that you know change caused RF in the shack, why not just put it back like
it was?

73,
Tom
Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member

"Only a white man would believe he could cut the top
off of a blanket, sew it to the bottom and have a longer
blanket."

-- Old Indian comment about Daylight Saving Time

On Wed, 11 Jan 2012 16:12:20 -0500 (EST), [hidden email] wrote:

[snip]

______________________________________________________________
Elecraft mailing list
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Amateur Radio Operator N5GE

Mel

Re: ladderline and balun question

In reply to this post by Cookie

OK, I will bite. Don if I understand you correctly, you have a square loop at 40 feet with equal side length.

If I may, I would be pleased to model it for you as that is what I did in my earlier productive life, hi. A few more particulars.

Length of each side and shape if not square.
Wire size and type, Al, Cu etc.
The impedance of the ladder line and type, window or open line and actual length

Last are there any obstructions near by. Some of this info has been said, but I would like a clean slat to start with.

Glad to help,

Mel, K6KBE

--- On Wed, 1/11/12, WILLIS COOKE <[hidden email]> wrote:

From: WILLIS COOKE <[hidden email]>
Subject: Re: [Elecraft] ladderline and balun question
To: "[hidden email]" <[hidden email]>, "Elecraft Reflector" <[hidden email]>
Date: Wednesday, January 11, 2012, 3:02 PM

Don, no one has that knowledge to share because every piece of any material in the area of the antenna and feed lines affects the impedance and efficiency of the unit. No calculation simple enough to be handled by our computers and programs and within our ability to simulate is accurate enough to be sure. You can either blindly experiment as you have done and stop when you get acceptable results or you can buy the best antenna analyzer that you can afford and measure the result from your try. This method will probably not be accurate enough to get it right the first time, but will help you zero in on a good result. The ambiguous definition of "good result" is open to individual preference.

Unfortunately, most who experiment with wire loop antennas do so in search of a low cost, all band, universally low SWR antenna which will perform with the high tower mounted, directive, resonant arrays. This is not possible! Even if you strike low cost from the list! The reason that all the big gun contest stations have a money is no object approach is that it is the only way to produce world class results.

But wire antennas and open wire feeders are interesting and fun to experiment with. Hams have been looking for this cook book answer starting with Marconi. Some have had many an interesting QSO on this type of antenna, but the easy cook-book solution that can be explained in 100,000 words or less has not yet been discovered.

Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

________________________________
From: "[hidden email]" <[hidden email]>
To: WILLIS COOKE <[hidden email]>
Sent: Wednesday, January 11, 2012 4:05 PM
Subject: Re: [Elecraft] ladderline and balun question

HI Will,

That is reasonable advice, to just go back and that is definatly in the plans. However, before I climb up on ladders and so on I want to learn more in case I have a feed line length issue.

I can add more ladder line but I want a way to see if there is the possibility for success not just throw a different length at it.   I also am wondering if the 4:1 balun causes excessive imbalance so again hoping someone with more knowledge can help me out.

All I know is that this is the friendlest and most helpful list that I am a member of because of the quality of Hams that use elecraft equipment so I am hoping that there is some knowledge to share.

Thanks
Don

~73
Don
KD8NNU

On Wed, Jan 11, 2012 at 4:46 PM, WILLIS COOKE wrote:

Don, when it comes to ladder lines and baluns the only real expert was Jerry Sevick and he has gone to a better place where they only use resonant beam antennas. Take anything anyone is living says about open wire feeders and baluns with a grain of salt. Put your antenna back like it was when it worked. Ignore further advice from the living. Since I am still living, more or less, feel free to ignore this advice as well!

Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

___________________________________

From: "[hidden email]" <[hidden email]>
To: [hidden email]
Sent: Wednesday, January 11, 2012 3:12 PM
Subject: [Elecraft] ladderline and balun question

Gents,

I have a ladder line and balun question that I hope someone can guide me
thru.

I had a good working antenna system with two antennas. First being an
Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
the air strung in trees. So the wire does touch the trees.

Dipole is fed with coax and choked at the feed point and the loop was
fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax to
the shack tuner. Then the amp and radio.   This combination was working
real well no RF problems in the shack.

I was advised that I would obtain better results for better SWR at
resonance and easier matching if I removed the 1:1 balun and went to a
4:1 balun. I made this change with everything else being the same. I
now had RF in the shack again.

I then added an isolation balun to the system by adding 6ft coax from
the output of the 4:1 to a balun designs 116du which is supposed to have
4500 ohms of choking impedance on 160m and over 5000 ohms choking
impedance on 80 and 40 meters.   This did not eliminate the RF and I am
still having problems.

So here is the question, is it possible that with the combination of
length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I am
at a feed line length that will be a problem no matter what I do.    I
keep looking at the internet to try and figure this out but I am
confused as some information I find says it only applies to 1:1 baluns
or other factors.

So anyone who can help me understand this feed line question I will be
greatly appreciative.

Thanks
Don

~73
Don
KD8NNU

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KXBill

Re: ladderline and balun question

In reply to this post by Don Wilhelm-4

Don:The gentlemen with the 1 wave loop on 160 could extend the 450 ohm feeder out where it presents a current loop That would place him at a current loop on 80, as well or, just continue with the 450 ohm line (a multiple of half waves) into the shack and couple up there.He could place the balun at at any current loop, or better yet, a link coupled balanced matching network in the shack.Bst RgdsBill-w7kxb

> Date: Wed, 11 Jan 2012 17:02:51 -0500
> From: [hidden email]
> To: [hidden email]
> CC: [hidden email]
> Subject: Re: [Elecraft] ladderline and balun question
>
> Don,
>
> According to L B Cebik's modeling, a 2 wavelength horizontal loop will
> have a feedpoint impedance of 180 - j125 ohms, and a 4 wavelength loop
> (the same loop used on 80 meters will have a feedpoint impedance of 235
> - j135.
> Both are good candidates for the use of a 4:1 balun - but that only
> applies if you mount the balun right at the antenna feedpoint. The fact
> that you have 60 feet of 450 ohm feedline changes the situation
> drastically - that is about 1/8 wavelength on 160 and close to 1/4
> wavelength on 80 - so the feedoint impedance at the end of that 60 feet
> of feedline is quite a bit lower - that is most likely why your 1:1
> balun worked so well. You can work with L B Cebik's antenna feedpoint
> impedances and the TLW application available from the ARRL to find the
> feedpoint impedance at the end of the 60 foot feedline, but I think you
> will find it closer to 50 ohms than to 200 ohms.
>
> The other question is what type of balun is your 4:1 balun - if it is a
> voltage type, it has no chance of stopping common mode current.
>
> My guess for why your current choke did not work is either that you did
> not place it at the right point on the coax, or it was at a point where
> the RF voltage was high, and in light of a high RF voltage (think
> impedance equal to 2000 to 4000 ohms, a choke of 5000 ohms impedance
> does not have much of a chance to stop any current.
>
> So bottom line - go back to what you had before, or put the 4:1 balun at
> the antenna feedpoint where it should work if your antenna is anything
> like L B Cebik's simulations.
>
> 73,
> Don W3FPR
>

Jim Brown-10

Re: ladderline and balun question

In reply to this post by KD8NNU

On 1/11/2012 1:34 PM, Ron D'Eau Claire wrote:
> You said the original arrangement worked fine. Why not go back to it?

Agreed. Don, you got bad advice from someone who didn't understand the
fundamentals of how antennas and feedlines work.

Strike the word "balun" from your vocabulary and start using words that
describe what the part is really doing. Have you noticed that the
manufacturers of these so-called baluns almost never tell you what's
inside, or give you any performance specs?
Many so-called baluns are really lossy transformers. Some are
combinations of common mode chokes, but the common mode chokes aren't
very good. Some are phasing lines. Often the companies (or hams)
selling this stuff have no real understanding of what they're selling --
they are businessmen, and it's monkey see, monkey do.

What you WANT at the feedpoint of BOTH antennas is a very good, low Q
COMMON MODE CHOKE with a high choking impedance and rated for whatever
power you're running. See the specific winding recommendations in my RFI
tutorial.

http://audiosystemsgroup.com/RFI-Ham.pdf

73, Jim K9YC
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Jim Dunstan

Re: ladderline and balun question

In reply to this post by KD8NNU

At 04:12 PM 1/11/2012, you wrote:
>Gents,
>
>I have a ladder line and balun question that I hope someone can guide me
>thru.

A 1 wavelength loop represents approximately 100 ohms non reactive
impedance. Feeding this antenna on its fundamental frequency is
relatively straight forward ... and it can be done with coax ...
using some tricks to get it down very close to 50 ohms. However if,
as is commonly done the loop is used on harmonics making it multi
band the situation is much more complex and the feed is changed from
coax to parallel feed line as you have done.

The impedance at the feed point increases with harmonics with the
addition of an increasing reactive component. It is common in such
antenna systems to make the transition from the parallel feed line to
coax as it approaches the shack .... since it is generally easier to
physically route it through walls etc ... and it is thought that it
radiates less than the parallel line (usually not the case).

It is possible to actually measure the complex impedance at the end
of the parallel line using an analyzer .... but inevitably there will
be a mismatch to the coax whether using a 4:1 or 1:1 balun. which
will cause radiation from the coax line. It is simply a matter of
determining if the amount of radiation from the coax section is
tolerable or not. It is possible to bring the parallel feed line
right into the shack and connect it directly to an impedance coupler
.... and in fact this was the usual method for many years ... and I
have done this with no adverse RF effects in the shack.

The easiest method of using a large loop on its resonant harmonics is
to install the antenna coupler right at the feed point and use coax
for the full feed line length. It is possible to make some guesses
as to the impedance at the end of the feed line at the different
frequencies given the length of the parallel feed line. The
experience you describe would indicate the impedance is rather low as
the 1:1 balun worked well.

The most common strategy for this arrangement is the cut and
try method. Stick with what works .... there are no magic rules of thumb.

Jim, VE3CI

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KD8NNU

Re: ladderline and balun question

In reply to this post by KD8NNU

Thanks Don,

I installed the SW that came with the Antenna Book.

My problem is I dont know how to model stuff so I dont have the
feedpoint impedance.

I am lucky someone is being kind enough to mentor me so I can learn this
stuff.

Cheers
Don

~73
Don
KD8NNU

On Wed, Jan 11, 2012 at 5:30 PM, Don Wilhelm wrote:

> Don,
>
> If you don't have TLW, you might have to invest in the ARRL Antenna
> Book - it is on the CD that comes with that book.
> It is "Transmission Line for Windows", and you can plug in the antenna
> feedpoint impedance, the type and length of feedline and the program
> tells you the impedance at the other end.
>
> 73,
> Don W3FPR
>
> On 1/11/2012 5:11 PM, [hidden email] wrote:
>> HI Don,
>>
>> I wish to look into the TLW application you mention. However, I am
>> not
>> what it is exactly. Would you please be so kind as to point me in
>> the
>> proper direction.
>>
>> I most likely will be going back to the 1:1 balun but the promise of
>> swr
>> of 1.3 on 160m was nice, which I have on the 4:1. Also it is a
>> current
>> balun.
>>
>> Thanks
>>
>> ~73
>> Don
>> KD8NNU
>>
>>
>> On Wed, Jan 11, 2012 at 5:02 PM, Don Wilhelm wrote:
>>
>>> Don,
>>>
>>> According to L B Cebik's modeling, a 2 wavelength horizontal loop
>>> will
>>> have a feedpoint impedance of 180 - j125 ohms, and a 4 wavelength
>>> loop
>>> (the same loop used on 80 meters will have a feedpoint impedance of
>>> 235 - j135.
>>> Both are good candidates for the use of a 4:1 balun - but that only
>>> applies if you mount the balun right at the antenna feedpoint. The
>>> fact that you have 60 feet of 450 ohm feedline changes the situation
>>> drastically - that is about 1/8 wavelength on 160 and close to 1/4
>>> wavelength on 80 - so the feedoint impedance at the end of that 60
>>> feet of feedline is quite a bit lower - that is most likely why your
>>> 1:1 balun worked so well. You can work with L B Cebik's antenna
>>> feedpoint impedances and the TLW application available from the ARRL
>>> to find the feedpoint impedance at the end of the 60 foot feedline,
>>> but I think you will find it closer to 50 ohms than to 200 ohms.
>>>
>>> The other question is what type of balun is your 4:1 balun - if it
>>> is
>>> a voltage type, it has no chance of stopping common mode current.
>>>
>>> My guess for why your current choke did not work is either that you
>>> did not place it at the right point on the coax, or it was at a
>>> point
>>> where the RF voltage was high, and in light of a high RF voltage
>>> (think impedance equal to 2000 to 4000 ohms, a choke of 5000 ohms
>>> impedance does not have much of a chance to stop any current.
>>>
>>> So bottom line - go back to what you had before, or put the 4:1
>>> balun
>>> at the antenna feedpoint where it should work if your antenna is
>>> anything like L B Cebik's simulations.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 1/11/2012 4:12 PM, [hidden email] wrote:
>>>> Gents,
>>>>
>>>> I have a ladder line and balun question that I hope someone can
>>>> guide
>>>> me
>>>> thru.
>>>>
>>>> I had a good working antenna system with two antennas. First being
>>>> an
>>>> Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft
>>>> in
>>>> the air strung in trees. So the wire does touch the trees.
>>>>
>>>> Dipole is fed with coax and choked at the feed point and the loop
>>>> was
>>>> fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax
>>>> to
>>>> the shack tuner. Then the amp and radio. This combination was
>>>> working
>>>> real well no RF problems in the shack.
>>>>
>>>> I was advised that I would obtain better results for better SWR at
>>>> resonance and easier matching if I removed the 1:1 balun and went
>>>> to
>>>> a
>>>> 4:1 balun. I made this change with everything else being the same.
>>>> I
>>>> now had RF in the shack again.
>>>>
>>>> I then added an isolation balun to the system by adding 6ft coax
>>>> from
>>>> the output of the 4:1 to a balun designs 116du which is supposed to
>>>> have
>>>> 4500 ohms of choking impedance on 160m and over 5000 ohms choking
>>>> impedance on 80 and 40 meters. This did not eliminate the RF and
>>>> I
>>>> am
>>>> still having problems.
>>>>
>>>> So here is the question, is it possible that with the combination
>>>> of
>>>> length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax
>>>> I
>>>> am
>>>> at a feed line length that will be a problem no matter what I do.
>>>> I
>>>> keep looking at the internet to try and figure this out but I am
>>>> confused as some information I find says it only applies to 1:1
>>>> baluns
>>>> or other factors.
>>>>
>>>> So anyone who can help me understand this feed line question I will
>>>> be
>>>> greatly appreciative.
>>>>
>>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>

Don Wilhelm-4

Re: ladderline and balun question

Don,

I gave you the antenna feedpoint impedances for a 2 wavelength loop and
a 4 wavelength loop from L B Cebik's simulations. Those impedances are
as close a one might get.

73,
Don W3FPR

On 1/12/2012 9:39 PM, [hidden email] wrote:

> Thanks Don,
>
> I installed the SW that came with the Antenna Book.
>
> My problem is I dont know how to model stuff so I dont have the
> feedpoint impedance.
>
> I am lucky someone is being kind enough to mentor me so I can learn this
> stuff.
>
> Cheers
> Don
>
> ~73
> Don
> KD8NNU
>
>
> On Wed, Jan 11, 2012 at 5:30 PM, Don Wilhelm wrote:
>
>> Don,
>>
>> If you don't have TLW, you might have to invest in the ARRL Antenna
>> Book - it is on the CD that comes with that book.
>> It is "Transmission Line for Windows", and you can plug in the antenna
>> feedpoint impedance, the type and length of feedline and the program
>> tells you the impedance at the other end.
>>
>> 73,
>> Don W3FPR
>>
>> On 1/11/2012 5:11 PM, [hidden email] wrote:
>>> HI Don,
>>>
>>> I wish to look into the TLW application you mention. However, I am
>>> not
>>> what it is exactly. Would you please be so kind as to point me in
>>> the
>>> proper direction.
>>>
>>> I most likely will be going back to the 1:1 balun but the promise of
>>> swr
>>> of 1.3 on 160m was nice, which I have on the 4:1. Also it is a
>>> current
>>> balun.
>>>
>>> Thanks
>>>
>>> ~73
>>> Don
>>> KD8NNU
>>>
>>>
>>> On Wed, Jan 11, 2012 at 5:02 PM, Don Wilhelm wrote:
>>>
>>>> Don,
>>>>
>>>> According to L B Cebik's modeling, a 2 wavelength horizontal loop
>>>> will
>>>> have a feedpoint impedance of 180 - j125 ohms, and a 4 wavelength
>>>> loop
>>>> (the same loop used on 80 meters will have a feedpoint impedance of
>>>> 235 - j135.
>>>> Both are good candidates for the use of a 4:1 balun - but that only
>>>> applies if you mount the balun right at the antenna feedpoint. The
>>>> fact that you have 60 feet of 450 ohm feedline changes the situation
>>>> drastically - that is about 1/8 wavelength on 160 and close to 1/4
>>>> wavelength on 80 - so the feedoint impedance at the end of that 60
>>>> feet of feedline is quite a bit lower - that is most likely why your
>>>> 1:1 balun worked so well. You can work with L B Cebik's antenna
>>>> feedpoint impedances and the TLW application available from the ARRL
>>>> to find the feedpoint impedance at the end of the 60 foot feedline,
>>>> but I think you will find it closer to 50 ohms than to 200 ohms.
>>>>
>>>> The other question is what type of balun is your 4:1 balun - if it
>>>> is
>>>> a voltage type, it has no chance of stopping common mode current.
>>>>
>>>> My guess for why your current choke did not work is either that you
>>>> did not place it at the right point on the coax, or it was at a
>>>> point
>>>> where the RF voltage was high, and in light of a high RF voltage
>>>> (think impedance equal to 2000 to 4000 ohms, a choke of 5000 ohms
>>>> impedance does not have much of a chance to stop any current.
>>>>
>>>> So bottom line - go back to what you had before, or put the 4:1
>>>> balun
>>>> at the antenna feedpoint where it should work if your antenna is
>>>> anything like L B Cebik's simulations.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>> On 1/11/2012 4:12 PM, [hidden email] wrote:
>>>>> Gents,
>>>>>
>>>>> I have a ladder line and balun question that I hope someone can
>>>>> guide
>>>>> me
>>>>> thru.
>>>>>
>>>>> I had a good working antenna system with two antennas. First being
>>>>> an
>>>>> Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft
>>>>> in
>>>>> the air strung in trees. So the wire does touch the trees.
>>>>>
>>>>> Dipole is fed with coax and choked at the feed point and the loop
>>>>> was
>>>>> fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax
>>>>> to
>>>>> the shack tuner. Then the amp and radio. This combination was
>>>>> working
>>>>> real well no RF problems in the shack.
>>>>>
>>>>> I was advised that I would obtain better results for better SWR at
>>>>> resonance and easier matching if I removed the 1:1 balun and went
>>>>> to
>>>>> a
>>>>> 4:1 balun. I made this change with everything else being the same.
>>>>> I
>>>>> now had RF in the shack again.
>>>>>
>>>>> I then added an isolation balun to the system by adding 6ft coax
>>>>> from
>>>>> the output of the 4:1 to a balun designs 116du which is supposed to
>>>>> have
>>>>> 4500 ohms of choking impedance on 160m and over 5000 ohms choking
>>>>> impedance on 80 and 40 meters. This did not eliminate the RF and
>>>>> I
>>>>> am
>>>>> still having problems.
>>>>>
>>>>> So here is the question, is it possible that with the combination
>>>>> of
>>>>> length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax
>>>>> I
>>>>> am
>>>>> at a feed line length that will be a problem no matter what I do.
>>>>> I
>>>>> keep looking at the internet to try and figure this out but I am
>>>>> confused as some information I find says it only applies to 1:1
>>>>> baluns
>>>>> or other factors.
>>>>>
>>>>> So anyone who can help me understand this feed line question I will
>>>>> be
>>>>> greatly appreciative.
>>>>>
>>>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
> ______________________________________________________________
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>