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Author Topic: Ladder line to 4:1 Balun Question  (Read 441 times)

KB1JCU

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Ladder line to 4:1 Balun Question
« on: September 04, 2020, 01:05:39 PM »

Good afternoon all,

It has been many years since I had been on the HF bands.  Approx. 15 years or so. 

I currently have a K1JEK long wire antenna that comes with approx. 80' of ladder line. 

For my Balun, I'm using an older W9INN Balun Box (Model MFJ-912)

My question: 

-  I assume I would strip the ladder line and have the metal wire connecting to both sides of the balun (the antenna balance line)

(Images below):

With the MFJ 912 Balun box, would I: 

A . Have the original nut that is connected to the balun box, then have the stripped ladder line wire, then small washer, then large washer then wingnut

B. Have the original nut that is connected to the balun box, the small washer, then the stripped ladder line wire, then large washer, then wingnut? 

For Grounding: 

How would I ground this balun box? 

Would I use copper wire connected to a ground rod (in the ground of course)

It has been years since I've been on HF and when I set this up, I want to make sure that I don't short my radio, or, worse, potentially cause a fire should I not properly wire the balun. 

I have attached images.  I would also like to wish everybody a great Labor Day weekend!

Dave
KB1JCU





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KB1JCU

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Re: Ladder line to 4:1 Balun Question
« Reply #1 on: September 04, 2020, 01:10:24 PM »

How do you attach images?   I’m trying to show an image of the balun that I have.  A picture is worth a thousand words.
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W9IQ

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Re: Ladder line to 4:1 Balun Question
« Reply #2 on: September 04, 2020, 01:46:30 PM »

This site doesn't directly host the image. Here is the simplest way to show a picture.

  • Start your eHam posting
  • In a different browser tab, browse to postimage.org
  • Drag and drop your picture there (you do not need an account/login)
  • Click on the "copy link" icon to the right of the "Direct Link:" box (second one down)
  • Return to your eHam posting
  • Click on the picture icon in the eHam toolbar (below the B)
  • Paste the link you copied from postimage between the two image tags (between  ...mg] and [/im...)

- Glenn W9IQ
« Last Edit: September 04, 2020, 01:49:59 PM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

W6MK

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Re: Ladder line to 4:1 Balun Question
« Reply #3 on: September 04, 2020, 02:15:50 PM »

As far as I can tell the K1JEK antennas are not "long wire" antennas. Which are not balanced antenna systems so probably unsuitable for use with a balun.

The antennas appear to be shortened (via linear loading) dipole or doublet antennas.

If the balun's balanced terminals are to be used, washers function as they do with any electrical/mechanical connection: the wire is placed between two washers with the terminal nuts on the outside, the fixed nut below the feed line connection and the wingnut above.

Set up the washers and wire connections so that the wire is held firmly; how you organize the washers is up to you. A washer in this case serves to isolate the wire from the turning force from the wingnut as well as to provide a larger contact point for both the lower part and upper sections of the terminal bolt.

You might set up the washer/wire connections in different ways on each terminal. After a year you can see which one works better. I doubt that there will be any difference.

You might consider putting some liquid electrical tape or other coating on the connections. Out here where we have marine air, stainless terminals with copper wire attached can corrode because of the salt-laden air.
« Last Edit: September 04, 2020, 02:21:02 PM by W6MK »
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W9IQ

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Re: Ladder line to 4:1 Balun Question
« Reply #4 on: September 04, 2020, 02:40:20 PM »

For clarity, the last two bullets on my last post are enhanced as:

  • Click on the picture icon in the eHam toolbar (below the B). You will see [­img][­/img] tags inserted in your message
  • Paste the link you copied from postimage between the two image tags (such as [­img]https://i.postimg.cc/CK0hdFTf/Example.png[­/img])

- Glenn W9IQ
« Last Edit: September 04, 2020, 02:48:26 PM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KB1JCU

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  • Posts: 34
Re: Ladder line to 4:1 Balun Question
« Reply #5 on: September 05, 2020, 05:55:38 AM »

I want to thank you all for your contribution.  I set up my 4:1 balun yesterday.  Now, for some reason, I can't get my auto-tuner to tune any of the bands.  My current radio is an Icom MKIIG.  My auto tuner is an MFJ. 

Always something...back to the drawing board.

I'll keep you all posted!
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W8LV

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Re: Ladder line to 4:1 Balun Question
« Reply #6 on: September 14, 2020, 02:31:05 PM »

Dear Sir,

I sent you the PDF spec sheet for your MFJ Balun. I hope that it helps, I too am confused on the question. Off hand, I can only recall this 4:1 being used for an end fed Zepp, where you have a 1/4 wave ladder line stub, and 1/2 wave attaches to the distal end of EITHER side of the 1/4 wave stub. Yes, the either side of the stub,  Such as:

                     (1/4 matching stub)
                          I
                     I--------o
__________I--------o
I
(Long wire here)

Round terminals=Balun Attachment points.

I don't know how this "pictograph" will look on your end, if you can't see it just google "Zepp Antenna" and There You Have it...
Here is one, I don't know if it is the best one, but you can find others:

https://images.app.goo.gl/vsW9LhTv2vJNq5t68

Does anyone know why eham doesn't support pictures?

All the Best!
73 DE W8LV BILL

                     
 
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WB6BYU

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    • Practical Antennas
Re: Ladder line to 4:1 Balun Question
« Reply #7 on: September 15, 2020, 07:35:37 PM »

The 4 : 1 balun can be use with other antennas that present a 200
ohm impedance (or 300 ohms to 75 ohm coax).  I use them for
flattened loops (or I use a quarter wave of zip cord as a matching
transformer).  I don't remember ever using one with a Zepp antenna. 
(I used a balanced tuner instead when I used a Zepp.)

For those not familiar with it, the K1JEK is commonly known as
the "Cobra" antenna:  a doublet using linear loading to cut the
total length roughly in half.  While you can use a 4 : 1 balun
between the end of the feedline and an unbalanced tuner, a
1 : 1 current balun is generally considered a better
approach these days.


A common reason for tuners not working is that the CW drive
isn't advanced far enough to generate an adequate
carrier for the tuning process.


Hope you get it working!

W8LV

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Re: Ladder line to 4:1 Balun Question
« Reply #8 on: September 20, 2020, 08:50:18 PM »

Hi Dave! As luck would have it, the illustration on page 50 of the QST mag that just got delivered (October 2020) shows the illustration/answer to your question I think. If not? Let us know here and we will try more to get it answered for you!

73 DE W8LV BILL
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