Talk:Balun

message: Too often people say balanced signals are two signals either side of ground or some other reference. Balanced signals work against each other and have nothing to do with ground or any other reference. Twisted pair communications lines are a typical example. Suppose one end of the line is referenced to either side of ground. Changing magnetic fields, typically 50 or 60Hz mains generated fields, change the currents in both but, because they are twisted, affect both by the same amount thus, on the other end of the line there could be many volts of common mode (both the same in magnitude and phase) 50Hz signal. By examining the difference between the two and NOT the absolute voltage (referenced to anything), the original signal can be retrieved. Frequently in various computer communications systems, both signals fluctuate either side of 2.5 volts and not 0.Euc (talk) 21:32, 7 June 2012 (UTC)
thread_title:  What's all this about either side of ground ? 

message: with the earth ground or chassis ground left floating or unconnected on the balanced side. 
:All this really means is that the secondary of the transformer is not connected to ground, right?  There's no ground in a transformer that isn't connected. — Omegatron 00:48, 16 December 2005 (UTC)
replies: text: I have not yet really figured out how transformer baluns work and are wired, but  I do understand what they do.  The function of the balun is more in the transformer than it is in the connections on the outside of the transformer.  The goal is to prevent certain current flows (common mode current in the coax shield) while allowing others (opposing currents in the shield vs. center conductor).  I should post a good schematic picture.  Each type of balun does its job slightly differently.  The choke balun prevents the outside current while the coax allows the inside current.  The narrow band ("hairpin") coax balun works by shorting out the common mode current with current 180 degrees out of phase -- which is why it is narrow band (you have to get the phase right). The transformer does something goofy with passing two out of three currents in opposing directions; the polarity of the winding connections is critical, but more than that I have not groked. --ssd 05:19, 3 January 2006 (UTC)
thread_title:  transformer ground 

message: I think possibly the pronunciation guide for 'twin-lead' is out of place here; possibly better suited to being moved into the twin-lead article itself? (anon)
:I agree.  Mostly.  Actually, this is an encyclopedia, not a dictionary; I'm not sure the pronuciation guide belongs in the twin-lead article either.  But I'll at least remove it here.  And proof read the article for anything else I've missed. --ssd 04:32, 3 January 2006 (UTC)
thread_title:  pronunciation guide for 'twin-lead' 

message: I don't know how to edit it myself, so I thought I'd just mention it here in case anyone wants to fix it. The picture of a 4:1 balun using a ferrite core has mispelled balanced (it's spelled in the picture 'balenced').
You edit the main page in the same way as you edited this one. Go for it.Euc (talk) 20:02, 3 July 2012 (UTC)
thread_title:  balun picture 

message: I'm too lazy to integrate its info into the article, but other editors may find this white paper on balanced video at Extron's web site a useful reference. It deals particularly with video over UTP, but the description and diagram of balanced signalling on page 4 seems clearer than anything in this article right now.
--rcousine (talk) 20:40, 14 April 2008 (UTC)
thread_title:  A nice white paper describing balanced signals 

message: This section describes what I would call a cable trap. However, I think the described mechanism is wrong. Looping the coax, and adding a ferrite core, creates a large inductance on the coax braid. The high impedance blocks current on the braid, but the mechansim is reactive rather than resistive, so it is not lossy. The lossiness of the ferrite core is irrelevant. Am I missing something? GyroMagician (talk) 02:34, 23 November 2008 (UTC)
replies: text: Looping the coax or using cores of ferite, iron or anything else, affects only currents on the outer of the braid. Currents on the inner of the braid and on the central conductor behave only as a longer piece of coax with no magnetic interaction. Currents on the central conductor and the braid's inner surface are already magnetically neutral to the outside world.Euc (talk) 21:39, 7 June 2012 (UTC)
thread_title:  Alternatives to Baluns 

message: There is no explanation of the difference between a "1:1 balun" and a "4:1 balun", or what those ratios mean. The page Transformer gives no clarification either.  —Preceding unsigned comment added by 208.68.113.227 (talk) 00:55, 28 March 2009 (UTC)
replies: text: The ratio refers to the impedance on both sides of a device. It really has nothing to do with baluns (balanced <-> unbalanced) unless a transformer is used as a balun in which case the device serves two purposes, 1) to convert between unbalanced and balanced line and 2) to transform the impedance. As well as baluns, the ratio 4:1, 1:1 or x:1 might also be used with a plain transformer used to transform an impedance in that ratio or change voltage in the square root of the expressed ratio.
Euc (talk) 21:54, 7 June 2012 (UTC)
thread_title:  Ratios never explained 

message: The impedance of coax used for amateur radios is 50 ohms; 75 ohms is used for tv. Rosattin (talk)  —Preceding undated comment added 08:30, 12 October 2009 (UTC)
thread_title:  Amateur radio impedance 

message: I read this article, and encountered:
"Baluns can be considered as simple forms of transmission line transformers. A more complex (and subtle) type results..."
On the whole, I found this article to be quite unhelpful. It seems to assume a huge amount of knowledge. This make it more like an "experts forum". I know quite a bit of basic electronics (little RF though), however I came away none the wiser.
Sorry.  — Preceding unsigned comment added by 173.180.215.68 (talk) 03:59, 8 June 2011 (UTC)
thread_title:  How about a transformer taxonomy? 

message: See this catalog page from DX Engineering:
http://www.dxengineering.com/Products.asp?ID=182&SecID=152&DeptID=25&KeyWords=True&ShowAllProductLines=&ShowAllParts=&ShowAllArticles=
Similar units may be found on the signal cables of a vast array of computer equipment.
:True, these clip-on ferrites are typically seen on computer equipment to prevent interference. But they don't usually offer enough attenuation to use them on an antenna - that either takes several turns of coax on the ferrite (as in the 1:1 balun photograph shown in the article), or a very large stack of ferrites. Either way, I think it is confusing to talk about 'wrapping' brittle ferrite material around anything. 
:On reading a bit more closely, I don't understand why this is offered as a balun alternative - coax wound on a ferrite core is a balun. GyroMagician (talk) 12:17, 23 January 2012 (UTC)
replies: text: I edited the text to refer to passing the coax through the material rather than wrapping the material around the coax. And I tend to agree that it might be better to just refer to it as another version of a balun rather than a balun alternative. Ham radio operators routinely use a small stack of ferrite beads rather than wrapping the coax around a ferrite core. Some kinds of coax do not respond well to tight bends, and the coax with beads may be easier to mount than a coax wrapped around a core. The stack recommended in the ARRL Antenna Handbook cited is 7 beads. Jc3s5h (talk) 15:09, 23 January 2012 (UTC)
replies: text: I like it - it's clearer now. GyroMagician (talk) 19:45, 23 January 2012 (UTC)
replies: text: I like what GyroMagician is saying. (S)he has it right. I am a ham operator but don't even bother with the beads or the turns because they introduce losses by increasing the length of the feedline. I simply leave the upper end of the coax outer ungrounded (not connected to anything except the antenna) and tape (wire ties) the entire length of coax to the steel/iron tower and, where I can, thread it through any iron pipes or tubing forming part of the structure. Ordinary iron is no good for RF transformers because it's too inefficient (too many eddy currents) but for chokes who cares? A bolt or any old piece of iron works fine. Eddy currents don't matter, in fact, improve the performance as a choke.Euc (talk) 20:28, 3 July 2012 (UTC)
thread_title:  Proof that wrapping magnetic material around coax is in use 

message: "They always use electromagnetic coupling for their operation."
Probably, this should be clarified. Fully Differential Amplifiers can be used to the same effect, numerous TI datasheets illustrate that.  — Preceding unsigned comment added by 98.231.144.58 (talk) 23:21, 27 April 2012 (UTC)
thread_title:  __Always__ use electromagnetic coupling? 

message: I see that 'baluns' are listed as being used to convert twinax to cat5.  Since the signal remains balanced on both sides, is such an adapter really a balun?  — Preceding unsigned comment added by 12.166.65.194 (talk) 15:07, 28 February 2013 (UTC)
replies: text: There's multiple factors involved.  First, it's probably also an impedance transformer, as twinax is coax and cat5 is twisted pair, which have very different impedances.  Second, if coax is involved, there is a chance for common mode current, and a balun would block that.  --ssd (talk) 15:24, 14 April 2013 (UTC)
thread_title:  Twinax? 

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thread_title:  External links modified 

message: The term "voltage balun" is used twice and the two usages conflict with each other: one says a voltage balun is an autotransformer, and the other says it's a classical transformer.
192.91.173.36 (talk) 21:43, 6 March 2019 (UTC)
thread_title:  Which is the "voltage balun". 

message: re your edit, it would appear that balancing unit is a valid acronym.  This is the definition given in the OED along with cites back to 1947.  They don't mention balanced-to-unbalanced as a definition so I would surmise that this is a later back etymology.  Here is a book source giving both definitions. SpinningSpark 11:39, 28 July 2021 (UTC)
replies: text: That seems like sufficient sourcing to add "balancing unit". I don't have access to OED so I can't add that as a source. The Air University training manual might be questioned as a reliable source. I use baluns on a regular basis, and have even built them on occasion. In my experience, balanced-to-unbalunced is what most present-day radio technical folks would give as the etymology, so I would like to see that etymology given first. Jc3s5h (talk) 12:32, 28 July 2021 (UTC)
replies: text: I agree, I had not heard of the term until I saw your deletion.  I think it should be reinserted but described as dated. SpinningSpark 17:39, 28 July 2021 (UTC)
thread_title:  Balancing unit 

message: It is mentioned a few times in the introductory paragraphs that baluns convert between balanced signals and unbalanced signals. To me this doesn’t make any sense. Aren’t baluns used to interface balanced lines and unbalanced lines (i.e. lines with or without impedance balance)?
Hope we can clear up this confusion. Gutten på Hemsen (talk) 01:56, 2 September 2021 (UTC)
thread_title:  Balanced signals or balanced impedances? 

message: The line that says "Baluns are present in radars, transmitters, satellites, in every telephone network, and probably in most wireless network modem/routers used in homes." is a bit redundant given that a "balun" is never really defined in the article, except that basically any loop of wire or inductor could be considered a "balun". Is a balun just a low-pass filter then? Someone above said the article is "too technical". No, it's the opposite. If we were being technical, we would drop the amateur jargon word "balun" and talk about the purpose of adding an inductor at a particular place in a circuit. 162.246.139.210 (talk) 16:02, 27 February 2024 (UTC)
thread_title:  Applications list