Great explanation video! I learn T-130-2 and others iron toroids are NOT good for wide range frequency applications, FT-xx-43 would be better and the ferrite toroids are more broadband behavior.... What you say about this? Thanks!
Thanks for watching. The T-130-2 works for qrp and HF just fine. The FT-xx-43 would be a better overall choice. I would use the FT type next time. 73, N7JFP
How do you make a 1:6 current balun for 300:50 ohm? Also, it appears that the number of turns sets the impedance of the transformar at specific frequencies but not the transformer ratio, therefor the number of turns doesn't define the 1:4 ratio. I wonder why the winding is done half-half instead of winding 2 wires all the way around, and then winding the 2nd set of wires all the way around as well, next to the other wires.
I have not made a 1:6 current balun. This site sells them. www.balundesigns.com/model-6113-6-1-current-balun-3-5-54-mhz-3kw/ Individual cores wound with bifilar pairs to create two 4:1 current baluns. The two baluns are then cross connected in series/parallel to create 6:1 current balun. Look up Jerry Sevick's book on Balun design. Good luck building it. 73, N7JFP
I am very sorry, but what you have made is a 4 to 1 balun (4:1) for a 200 ohms antenna. A 1 to 4 balun (1:4) is a step up transformer used for a COBWEB antenna which has a 12.5 ohms impedance when complete. The 1:4 balun brings the matching circuit (antenna) from 12.5 ohms to 50 ohms. Also for a much better result a FT240-43 toroid ferrite core is recommended for any type of balun for HF (all HF bands). 73's de M1ENE
at 10:09 You mention input is on the left and output on the right. To clarify. When you say input are you meaning from the antenna or input from the transmitter? I am assuming input is from the antenna to make it 4/antenna side to 1/coax to the transmitter. Thanks.
1 to 4, 50 to 200, Transmitter in/Antenna out, Left to right. A turn thru the toroid is a pass. On mine one is 8 and the other is nine. It still worked so I didn't change it. Thanks for watching. 73, N7JFP
Thanks for the video, I made a two ferrite ring version of the guanella version you have shown, though the ferrite rings were unknown the SWR reading across the frequency range I required was excellent :-) I have a spare ferrite ring so I think I'm going to make the version you have shown here. As for insertion loss and rejection of common mode currents, well I don't have a clue, it's got to work better then the air cored 4:1 i have on my OFD dipole at present.
+Michael Katt I saw someone else build a 8 turn balun, so I built one and a 15 turn model to see if it really worked. The toroid itself is built for a certain frequency range that included HF. I didn't worry about reactance or insertion loss. The main concern was the low SWR value within the HF band. 73, N7JFP
12/13/14 I'm a bit confused...Both your winding look the same. Both start and finish in the same position. One set of winding suppose to go clockwise and the other counter clockwise or am I looking at this all wrong ?
Hi, At 07:35 you see both sides done. Notice both sides of balun the wires come out of same side showing that they are wound in opposite direction. It can be confusing. Thanks for watching. 73, N7JFP
At the end I find an instructive video where the formula of the turns appears. They all say how many, but they do not give the formula. Very good video, I congratulate you and I will try to build 1 for me, what I would like to know is what was the method you used to select the ferrite core ?, I would like to make one for 1,500W PEP. 73. EGY (KP4EGY)
The wire chart website has gone down. The size of the toroid will limit the gauge of wire to wind. 18 or 16 work fine. Try one and see the results. 73, N7JFP
The objective is to get an impedance match between your antenna feed line and the antenna. Coax (52 ohm) to OCFD (200 ohm) could use the 1:4 balun. Read more information on balun design in one of Jerry Sevick's books. Lots of variables and lots of different designs and applications, - - 73, N7JFP
I used 18 gauge copper wire with 8 turns thru the middle. It does not matter how the antenna or coax is attached. Both sides of windings are the same. The left side is the input and the right is the output. Do search on Internet for more articles on Guanella 1:4 balun. Have fun building it. 73, N7JFP
Tom Smith I made both to see if number of turns really made a difference. I did not see much difference. Next time, I would try only 4 turns of 14 gauge wire. 73, N7JFP
The purpose of a balun is to allow a balanced antenna (or load) to connect to an unbalanced transmission line without introducing common mode currents. The most important characteristic of a balun is the common mode impedance- that determines the degree of balance. The next important feature is the insertion loss. So it seems you have missed #1 and #2 and settled for measuring SWR- which gives no indication of the balancing efficacy or the loss of the device. Dale W4OP
Agreed. I think the terms 'balanced' and 'unbalanced' are deeply confusing. The currents and voltages in coax are just as balanced as they are on a twin feeder when things are working as normally required. The feeder fields are different, of course, one radial/concentric or co-axial, and the other identical but opposed, but the terminology of 'balance' adds more confusion to an already confused area. Coax is different to twin feeder (as you rightly say) because it has two modes of transmission, the normal mode, and the second one, down the outside of the cable outer and a single conductor. Stopping the second mode is the key here, because that is an 'unbalanced' mode. The outer of a coaxial cable is just another wire EM fields, so currents will flow on it, just as they do any wire. The coax does not know that you do not want the signals from those fields, so you have to stop them some other way. Current baluns seem to largely work by stopping unbalanced current flow, which is partly why the term 'unbalanced' is so misleading. One of the simplest is to put a ferrite ring around the coax. It works well, stopping the currents on the outside.
The 18 gauge should handle 200w. 14 ga-500w, 12 ga-1000w. The wire gauge and the thickness of the insulation on the wire will effect the impedance of the transformer and the frequency response curve. I have only used it for QRP operations. I would build one using the materials I have on hand and test it. Good luck, 73, N7JFP
@dg0sa Thanks for watching. This was my first toroid winding. The next one I wound had 15 turns per side and it has a better SWR response. I have just read "Transmission Line Transformers Handbook" improved designs by Jerry Sevick, produced by Amidon Associates. There are a lot of variables to consider when winding a toroid. The physical size, power rating, wire size, frequency bandspread, composition of the toroid and spacing are some of them. So much to learn. 73, N7JFP
1:1 impedance match is for stopping current from coming back down the antenna feed line. 1:4 impedance match is (50 ohm to 200 ohm) like an Off center fed dipole type. 73, N7JFP
The problem with toroids is NO identifying labels on them. A toroid at 60Hz may not work like you want it to at 25 MHz. It would be best to buy a known value toroid made for a specific purpose. 73, N7JFP
Is there anything to stop you using insulated stranded wire? assuming that it was thick enough, and could go around whatever toroid you were using??? why use enamelled single core??? any special reason???? Des
I was following Sevick's book on balun construction with solid core wire. Using multi-strand wire will bring other factors, like capacitive coupling and skin effect in to play. I have not built baluns with stranded wire. Build one and find out what happens to frequency response. Always interesting to learn what works and what doesn't. 73, N7JFP
N7JFP thank you for your prompt reply sir.....I'll give it a try...I've got a couple of T300 -2 cores on order, so it'll be quite hunky...I hope!! I did see a posting on QRZ.com where a guy said he's built loads of baluns and used solid and stranded insulated wire and never found any major difference...we'll see...73's Des
N7JFP Hello Sir....I tried the balun with stranded wire....I hooked it up to my rig, and into a 50 ohm dummy load...it shows an SWR of 3:1, which I think is too high. I don't have antenna analyzer, so tried the SWR way. I am new to building baluns, and I'd like to make this work!!! it's supposed to be a 1:1 balun wound on a pair of T300-2 cores. Could I have your e mail address and I'll send a couple of pics...maybe you'd have a look and see what I'm doing wrong....My email is ok on QRZ.com Thanks Des G4OBB
Desi kaylor Without the Analyzer to show the frequency response it is hard to determine what is wrong. The smallest change, number of turns, spacing, wire size can shift the freq response curve up or down. 73, N7JFP
This balun is wound incorrectly. Both sides of the torroid should be wound in the same direction. See TRX lab video #105. He did it correctly. You should be showing your polarity (dot) marks as he does. I did a mesh current analysis using mutual inductances and it came out exactly right using TRX’s polarity directions. As he indicates what you have is two stacked auto transformers giving a turns ratio of 2 and a impedance transformation of N squared or 4.
dear sir i have toroid 130-2 please tell me how many turns size of wire to make balun 4:1 where to conect female pl-259 and dipole wire if you have any plan or any photos to see the conection thnks very much sorry to bother de sv1bix kkk.;73
They function as a transmission line transformer by reducing the impedance mismatch that occurs between the transmitter and the antenna. This allows more RF power to be radiated from the antenna. 73, N7JFP
Second winding should be wound in "series aiding"... not "series opposing"... so it's wound wrong. BTW, for best performance, each pair should have its own core.
Therein lies the problem- how many cores, how many turns? One can't just wind some turns of coax (or balanced wire in this instance) on a core and assume that it will then effectively choke off the common mode current- in fact, the wrong combination can increase common mode. The 2nd issue lies in the fact that one cannot make a 4:1 CURRENT mode balun on a single core. What the author has constructed is a 4:1 TRANSFORMER with completely unknown choking characteristics. His transformer must then be followed by a 1:1 choke with high real part (R) of the choking impedance. If one does not have access to a commercial VNA, you can purchase one of the nano-VNA's and learn how to use it to measure the common mode impedance of a 'balun' or 'unun' versus frequency. Dale W4OP
O.K. so what is the difference in a 1:4, or 4:1, or 9:1 balun if your using the same T-130-2 and 18 gauge wire? I know the toroid's diameter, thickness & inside diameter makes a difference as well, I guess I just don't completely understand how this little doughnut works. I'd like to see you show the difference on an oscilloscope experiment. Now that would be worth watching!
You do count the wire thru the hole. One side does have nine turns and the other side has eight. The response curve should improve if they were matched. It worked with the 8 to 9 turn. I would try to match next time, 73, N7JFP
Normally a "turn" was one full wrap. Not how many times is passed through something. Might be different dealing with cores but other aspects of life it takes going back to the start point to be considered a full wrap / turn.
Because you don't get enough impedance to kill common mode currents across the bands. This video doesn't deal with your core question - what benefit do I get for this extra effort. The balun requires ferrite not dust iron as per video. If you are using ferrite, yours probably will work better, but not be the best you can achieve.
Now I maybe wrong here but after watching this a couple times I didn't some looking in my extra class study book from ARRL...Chapter 4 page 40 and I quote "Proper turns counting is important when you wind a toroidal inductor.Each pass through the center of the core must be counted.Part A shows a 1-turn inductor and Part B shows a 2-turn inductor."....As you look at the photo part a is the wire going through the center once and part b going through twice.With that being said I think you are counting it wrong.It would make 10 turns by the book not 8 if I am counting right on pause at 4:11..You are right if you count the outside but not the number of turns as far as the numbers by the books :D...I know I'm being a silly nitpicker lol
The next Balun I make I will be more careful to count the Inside turns instead of Outside turns. In this case the out come for SWR and freq response did fall within what I needed. There is some gray area for performance with all the variables in making the Balun. It is a good starting point in construction of Baluns. There is so much to learn. 73, N7JFP
Just to add a little to what David says below. The -2 in the T130-2 means that this is Micrometals material-2. You can usually tell by the color of the toroid, although this particular one is a little confusing since Micrometals says this would be a Red-Clear and in the video it is Red-Brown. Not sure what Red-Clear is supposed to look like. www.micrometals.com/products/materials/rf/
@@aaronmattmiller9304 Well I have some cores that are shinny and some dull. Wonder if the shinny ones have a clear coat on them. I have yellow ones that are shinny and a some with 2 colors that are dull. Just a thought.
There is 9 turns on the first wind and 8 on the second. It still worked ok. Maybe it would of been better response if matched. Oh well, next time. A turn is when the wire goes thru the center of the toroid. Thanks for watching. 73, N7JFP
