Posted by
Mel on
Jan 11, 2012; 11:37pm
URL: http://elecraft.85.s1.nabble.com/ladderline-and-balun-question-tp7179004p7179205.html
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
______________________________________________________________
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
______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.html______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.html