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 Post subject: Correct way to connect Balun
PostPosted: Mar Sat 24, 2012 6:13 am 
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Joined: Sep Mon 01, 2008 6:05 pm
Posts: 258
Location: Alberta, Canada
I bought one of these 10:1 Baluns for my longwire antenna.
http://www.conceptionrb.com/boutique/pr ... cts_id=143

What would be the best way to connect this to the wire? It has a stainless steel eye loop, and a wing nut with a couple flat washers on the threads of the eye.

Should I just hang the balun on the antenna wire looped through the eye, and solder a short length of wire to the longwire, and attach the other end under the wing nut? I think this would be the most solid connection.

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2) Increase bias until plates are no longer flame orange.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Sat 24, 2012 1:46 pm 
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Joined: Feb Fri 17, 2012 11:32 am
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Location: Valatie, N.Y. USA
This shows with picture how to hook things up.

Yours may be a little different since it is a different brand but the basics are covered;

http://www.balundesigns.com/Installation%20Notes.pdf

Hope that helps.
Tom

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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Sat 24, 2012 3:33 pm 
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Location: Somers, CT
The metal eye is your mechanical connection, to support the pull of the long-wire.
The flying lead is what you would use to make a good electrical connection
between the balun and wire antenna.

Peter


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Sun 25, 2012 1:08 am 
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Joined: Mar Tue 20, 2012 10:59 pm
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The best way to use a balun with an inverted-L (long wire) antenna is NOT to locate the balun up at the end of the antenna wire. When you do that the coax has to be suspended in the air and in that case the coax shield can become part of the antenna system, which feeds noise into the antenna via what is called the common mode. I just posted a reply to the thread titled 'I need some antenna ideas for my new Drake R8' where I described the best way to build an inverted-L antenna using a balun. It takes a little more effort than the basic long wire design but you will get an antenna that has much less noise from all the things in your house that radiate RF noise.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Tue 27, 2012 12:56 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 276
Location: Oregon
It sounds like you are using coax for the feed line to a long wire which I guess is end fed ,not a dipole? In that case you have an unbalanced feed line (coax) feeding an unbalanced antenna (long wire). From the above I would guess that an unun would have been a better choice than a balun. I am sure some others will comment on this. Bill


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Tue 27, 2012 1:24 am 
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Location: Palmerston North, New Zealand
IMHO what the pic shows is an "unun" - only a single input, which I take is the "tail" - which may or may not be joined to the ring at the top, and then an SO239 socket on the bottom. I guess the outer shield of the SO239 is expected to be the ground return for the primary of the unun, in that case I would ground the outer with a wire to a ground rod - a metal hose clip works fine for me. I turned my "short" longwire into an OCFD with the addition of another 6metres and then fed both ends into the primary of a homebrew 9:1 balun. The secondary coax shield is grounded at the base of the mast as before. A broad scan from 2 to 20MHz shows I no longer have that big dip at 8MHz!

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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Tue 27, 2012 7:27 am 
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Joined: Sep Mon 01, 2008 6:05 pm
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Location: Alberta, Canada
It is indeed a un-un, or an unbalanced impedance matching transformer. I am using it on an end fed longwire, with RG/6 coax. I'm going to hang the transformer by the eye on the antenna wire side of the dog bone insulator, and I'll solder a small lead wire from the solder tab on the transformer, and the other end to the wire.

Thanks for all the replies.

_________________
Alignment Instructions:
1) Adjust C158 trimmer for least smoke
2) Increase bias until plates are no longer flame orange.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Tue 27, 2012 4:52 pm 
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Posts: 14393
Location: Southern NH, 03076
While feeding the coax from the top is the best method for a straight longwire the unun is an autotransformer so there will be antenna currents on the outside of the RG-6 shield and there will be vertical polarized local noise pickup. A bare wire downlead is much noiser. You need a "shield" balun at this point which is simpy a foot or so of ferrite beads over the coax at the unun end. You can build or buy. Another one at the receiver may or may not help and you should also consider a good ground at the receiver end.

I can see that the description was likely written by someone from Quebec :roll:

Adding another wire to the antenna at another angle and length will tend to flatten out the dead spots where the balun is actually detrimental as Marc was leading to.

Carl


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Wed 28, 2012 4:31 am 
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Here's an article (below) that helps to explain why it's not a good idea to locate a balun (un-un) at the end of a horizontal antenna wire and then run a long length of coax down to the receiver. That set up allows the coax shield to become an antenna for noise reception via the common mode which is coupled into the center conductor of the coax at the balun. The best design for an inverted-L is to put the balun near the ground at the bottom of the vertical wire (not coax) which comes down from the horizontal wire. That way you can get a good ground for the balun and coax shield with a short ground wire to a nearby ground rod. The vertical wire of the inverted-L helps it to respond to signals which the horizontal wire is less sensitive to, making the antenna more responsive overall. The coax runs on or in the ground from the balun back to the receiver. This further grounds the coax shield so it doesn't pick up any radiated energy from local noise sources.

http://www.hard-core-dx.com/nordicdx/an ... gbal2.html


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Wed 28, 2012 4:26 pm 
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Location: Southern NH, 03076
There is a big difference between the proper way and what some SWL groups believe in; they are similar to audiophools.
I already mentioned how to remove the shield signal, try reading it again....its worked for decades.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Wed 28, 2012 9:11 pm 
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Joined: Mar Tue 20, 2012 10:59 pm
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I got it the first time I read it. I was aware of the technique for decoupling the common mode signal in the coax shield using ferrite beads but it doesn't offer some of the benefits described in the article I referrenced. Grounding the coax shield with the balun near the ground is more effective than using ferrite beads at the high end of the coax when it's connected to a horizontal wire. This is because the former method allows for a short and therefore effective RF ground wire. When the coax is run on the ground to the house the shield can also be grounded a second time with another short ground wire before it enters the house. This makes it practically impossible for the shield to become a common mode antenna. Then there are the reception benefits of an inverted-L compared to just a horizontal wire.

BTW- The author of that article was not just some member of a SWL group. He is a PhD electrical engineer at MIT who works on projects for NASA and happens to be a shortwave listener too. Sometimes book learning actually works.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Thu 29, 2012 3:44 pm 
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Joined: Oct Sat 20, 2007 3:36 am
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Location: Southern NH, 03076
Grounding the receiver end of the coax shield has always been part of a good installation and in the way I described simply comlpetes it.

Your way still leaves the downlead open for signal pickup, especially from very local noise. Maybe your PhD buddy tried it out in the dead of winter in a remote location as many "extreme" SWL's do :shock: However Im more for the comfortable real world of my own home as I only have a simple MSEE and have only been a SWL since the early 50's.

I also wind my own matching transformers as real transformers with care to minimize capacitive coupling and not autotransformer ununs which does absolutely nothing for common mode currents. For some installs another real 1:1 or other ratio transformer can add further isolation.

Maybe if you stick around on ARF awhile you will pick up many other good ideas and myth busters :?:
BTW do you have a name or did you just show up here as an anonymous instant expert?

Carl


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 12:25 am 
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Joined: Feb Mon 08, 2010 7:54 am
Posts: 21
WHAT ABOUT THE "UGLY BALUN"? SIMPLY 18 OR MORE FEET ON A 3-4 INCHES DIAMETER TUBE? SHOULD WORK EQUALLY WELL AND CAN BE MADE LIGHT WEIGHT.
VINCENZO


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 1:42 am 
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Joined: Mar Tue 20, 2012 10:59 pm
Posts: 39
The problem with RF grounding of an antenna coax shield is that any ground wire longer than a few feet is essentially useless at RF frequencies. It acts more like an antenna than a ground wire in that case. That's why the coax needs to be close to the ground whenever possible so a short ground wire can be used. An inverted-L antenna by definition, is supposed to have a single vertical wire coming down from the end of the horizontal wire. It's important to have that vertical wire as part of the antenna system so it will respond to signals which the horizontal wire is less sensitive too. In the design I have been discussing, the vertical wire is located at the far end of the horizontal wire where it will be less likely to pick up noise from the home environment. I have been using this design for several years with good results. It was first discussed in the popular literature by John Doty, the author of the article I mentioned. He did extensive testing of various ways to reduce the noise reception of coax fed HF antenna systems.
Since you seem intent on personalizing this discussion I'll simply add that I joined the group to gain some information on boatanchor receivers and perhaps to share some of my experiences too. I'm more than willing to learn from anyone that shows some common consideration and respect. Telling someone to "try reading it again" " is a good way to get off on the wrong foot with anyone here. I'm sure we could both learn a lot from Mr. Doty on RF theory, but I'm not so sure you would be willing to do so.

Jon


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 2:01 am 
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Joined: Feb Mon 08, 2010 7:54 am
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A technique to screen a long ground line is to use a shielded cable. The center conductor will be the virtual ground, the extremity of this cable will have tied together the center conductor and the shield to an available ground road(s) or cold water iron pipe . Doing so makes a "ground" RF screened and electrically to ground.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 3:00 am 
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Joined: Mar Sun 22, 2009 3:56 pm
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Location: Boston Area
Sounds like a rather arrogant noob that changes his description with every post and that URL is really a joke
Eric


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 3:23 am 
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Joined: Oct Sat 20, 2007 3:36 am
Posts: 14393
Location: Southern NH, 03076
Since this thread is about a long wire why are you wasting our time going on and on about an inverted L which is totally useless for receiving in a surburban enviroment that is full of digital and other crud that is vertically polarized? That noise is the biggest issue facing ARF members.

Your PhD is also confused in a few areas but thats not a subject for this thread.

Your last revision has me confused now....why a vertical wire at the far end and another at the near end? A far end down wire with the coax feed at the far end has been discussed on here for years, its nothing new and works when the local crud is not intense. Properly decoupled and grounded the coax can be any length and pick up no signal, something you completely fail to understand. One of my receive feedlines is 750' long and there is zero pickup and the antennas its connected to are relay controlled for multiple directions. No magic as the concept has been around for decades as has the 4 wire transformer concept I described yesterday. It didnt requre a PhD either and I certainly lay no claim to it.

IF you can offer something new then by all means do so but that SWL site certainly doesnt; its all a mishmash of the good and ridiculous, Ive read it long before.

Carl


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 3:58 am 
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Joined: Sep Mon 01, 2008 6:05 pm
Posts: 258
Location: Alberta, Canada
I actually found much ambiguity in that article. I know what current flow is, but what the heck is energy flow? Perhaps it's an attempt at wording the concepts of differential signal and common mode rejection in lay mans terms.

_________________
Alignment Instructions:
1) Adjust C158 trimmer for least smoke
2) Increase bias until plates are no longer flame orange.


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 3:11 pm 
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Joined: Oct Sat 20, 2007 3:36 am
Posts: 14393
Location: Southern NH, 03076
Its written by a PhD, what do you expect?

In English it means that a three terminal autotransformer balun is a voltage balun since all terminals are on the same winding and just tapped as needed for impedance selection. A Variac is an autotransformer.

A current balun is a true transformer with independent windings and the energy transfer is by magic, aka inductive coupling. The one in your radio has independent windings

IOW it all boils down to differential and common mode in the end as you surmised.

With a 3 terminal voltage balun such as yours the coax shield floats at the antenna end but you install a bead balun up there also as I already mentioned. Then try the radio realizing this is the minimal configuration and the only ground is thru the AC line 3rd wire. A copper water pipe is also a choice to add in.

If noise is still bad then a 4 wire (2 windings) transformer is needed at the house entry. The ratio is 1:1 for receivers with a 50-75 Ohm input and a 4:1 to 9:1 ratio for a balanced input or a single wire. The antenna side winding ground goes to its own ground rod. The radio side ground goes to its own rod at least 10-15' away and you will have to experiment to see if that copper pipe in the house helps.

Having the antenna fed at the opposite end if it is further away from homes is a good option requiring only a small change and that is to ground the coax shield as soon as it reaches it and then run more ferrite beads over the section going to the house at that ground point. It is often better to leave the house end ground lead floating and use just a receiver winding ground rod.

Using quad or tri shield and flooded RG-6 will guarantee no signal pickup (and a rodent retarder) as long as the other steps are followed. Any comments that the coax will always pickup signal is the result of very misguided information often started by an incompetent source and repeated forever. A ground block can be purchased to connect wherever a ground is needed. These are all standard and economical CATV components available at Home Depot and others.

If you feel you need a vertical antenna because of the LW directivity then install a seperate one far enough away so the two antennas dont couple. It should be as far as possible from homes and power lines. A cheap 2 position switch can be used at the receiver. Personally, Id install another LW at a right angle or wider as suggested much earlier by another and connected together. THAT is an L configuration that works.

Dont be afraid to experiment with grounds as there is no one size fits all rule.

Carl


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 Post subject: Re: Correct way to connect Balun
PostPosted: Mar Fri 30, 2012 4:21 pm 
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Joined: Sep Mon 01, 2008 6:05 pm
Posts: 258
Location: Alberta, Canada
I haven't measured it with an ohm meter yet, but I'm willing to bet the primary and secondary winding grounds are tied together to the coax shield. If I could open up the housing, I could lift the antenna side winding and install a separate ground terminal for the antenna winding.

I'm going to try it as it is first. I live in the country, so any nearby interference is more than likely my own. For years I've used the antenna with the center conductor of the RG6 connected directly to the longwire, and the shield floating at the antenna end. The coax shield is grounded to a ground rod through my lightning spark gap just before it enters the house.

Where's a good source for the ferrite beads? I assume the inner diameter is around 5/16 or 3/8? Is the ferrite composition important for this application?

_________________
Alignment Instructions:
1) Adjust C158 trimmer for least smoke
2) Increase bias until plates are no longer flame orange.


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