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Ham Radio - The back yard vertical part 3. Winding the 1:1 common mode choke
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- เผยแพร่เมื่อ 7 ก.พ. 2018
- C'mon spring! I'm getting anxious to get this antenna up and see how it's going to perform.
By popular request, I've uploaded the enclosure files to thingiverse.
www.thingivers...
The original page the diagram came from. Also more information there.
vk6ysf.com/balu...
My page on Thingiverse where you can download my 3D parts.
www.thingivers...
Part four, putting up the antenna:
• Ham Radio - The back y...
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The crossing section passes through the inside of the toroid and induces magnetic flux in the material. It counts as a turn. You have 9 turns in that drawing sir.
I really appreciate how you arrange / produce your videos. Well-organized and not a lot of wasted time. Thank you.
Every turn through the ferrite is in the same direction, both before and after the crossover turn. Every turn is made from the front side through the centre. Turns are only counted inside the core. The crossover part is only there so the result winding has wire entering one end, and leaving the other end of the core.
Hi Kevin, Recently I built your version of this common mode choke. I have today completed checks with it on all HF bands and on 160, 80 and especially 10 this choke worked very well. I intend to put this between my 9:1 EFHW and tuner. Thanks again for your excellent videos, so well presented for the homebrew Hams, still many of us active and appreciate your time and effort. G4PEY
Thanks for sharing this tutorial. I recently made a 4:1 and a 1:1 using garage door wire. It made the winds very easy, and the wire is marked for polarity, which is also handy. It also made consistent spacing a breeze. Always put a load on the antenna end and check the SWR when you're done. For the 1:1, a 47-ohm resistor does fine, whereas the 4:1 can be tested with a pair of 100-ohm resistors in series.
I made a «common mode choke» using a RG-58U on a toroid and put it in the back of my radio. It actualy worked very well. Used the same method as shown in the video, except for using the one coax cable, of course. Thanks for the video, Kevin.
One possible concern with winding coax is the tight bends you put in it. When coax is bent sharply, the center conductor can 'migrate' through the dialectric and make contact with the shield. Especially if you pump serious power through it and the center conductor heats a bit.
@@loughkb Agreed, Kevin. I used a FT240-31 so it seems, at least for now, that it works ok. Going to use the core for a 9:1 later on. We will be traveling the the very north west at 71 deg. north so I am planning to make the same one as you did for the back yard vertical antenna. Looking forward to the next vids. 73 LA6YJA...
When measuring the wire don't forget the diametric cross over link as well!
Never cross the streams!!!
Hi Kevin, Larry sent me. I just started up again after 30+ years and find your channel helpful seeing how technology has passed me by. lol
I found that video fascinating. Thanks Kevin.
Very useful video and the process of designing the box was useful to see.
Thank you for this video! You are truly a great help to new people in ham radio like myself, its almost like having an "ELMER" on call. Cant wait for the actual antenna build. 73 KD9GJX
You make this look slick as a button! Great tutorial!
3D printer seems great for custom parts, much nicer than drilling project boxes (and trying to find a suitable size at first!)
Looks like I need to add 3D printing to my hobby list! Thanks for the videos.
Thanks for sharing this tutorial. Recently I buy 3D printer and I appreciate your thinkercad tutorial. Thanks for excellent video. Alex, PY4EU
Hello Kevin awesome video. I use tinkercad nearly everyday. One thing i did when you were doing the lid i would've turned the box in to a hole and used the box as a stamp and placed the box over the lid and made a perfect insert so the lid wouldn't wobble. Keep up the awesome vids.
Great video!!! I love your helping hands board great idea. at 17:28
second winding is not "out-of-phase" . use your right-hand rule of magnetic fields (hold you thumb, index and middle finger to create the right-hand rule)
Thanks for sharing. Very helpful. 73
Hi Kevin. Once again a really great video series.
This is the Right Balun that can be Use with a Loop Antennas to,
It seems you don't know the "Mini Ringkernrechner". This is a great help with all toroids - even unknown ones. But , thank you for the film :)
Kevin, why not start your winds at the center? Secure the diametric sides with zip ties, then wind on...
I am going to make one 9-1 now. I am on my working table.
Thank you sir
An easy way of "marking" the wires is to reverse one of the strands. One manufacturer's wire characteristic numbers "reads" right to left, the other is reversed.
Thank You, Great video. 73
Very good MAKER IDEA is to make MODULES to use on other projects .... you need to include a generic box with lid with a LIP to add to the TOOL BOX shapes =)
Thank you, just the instructions I need at the moment for the common mode choke balun.
How were the 8 turns decided? Lots of space on the toroid for more?
Some designs show windings of co-ax rather than twin. Any preference?
Ah More space on the drawing than on the toroid!
Looks great thanks
Fantastic you give us one big gess how fun you make tha box love that PY1AX sinple pratlic and good so thank you in did 73.
Thanks for the informational video! Question- Some people use 8 turns some 12. Is there a difference other than the turns? Thanks for the video.
at 3:30, you're wrong.... that;s not how it works. Differential currents zero each other out (no magnetic field, so no inductance, so nothing to stop the currrents) no matter how it's wound.
Sweet i am making an off center fed dipole with a 4:1 and ill need to make a common mode choke for down the coax..
Most AC line cord has insulation rated at 600V, some may be higher, Why not use that? The two conductors are permanently in place and stable.
I've seen people do that. Sure, it works.
How does the balun input Z look with VNA sweep with outup terminated in 50 ohms?
Please explain something to me.
The blue winding is connected to ground at each end. Doesn’t that effectively short out the blue winding of the choke??
With RF impedance is what matters, AC resistance which varies depending upon inductance. Inductance. A DC short, but not a short to RF.
When you first started with tools and materials I thought you had a slip-stick laying there! lol
I have an ocf with a 4:1 balun and have a difficult time tuning it up. Would a 1:1 after the 4:1 help?
Yeah, I think so. But you'd want it a few inches down the feeline. Keep the 4:1 up at the wires where the impedance mismatch is.
Mr. KEVIN, please give me information, what is outside, inside diameter and thickness toroid for 27 mhz, and number of turns if balun 1:1, thansk
Exactly the same as shown.
OK, take a deep breath and laugh at me first, but i have a question: Will this serve as a 1:1 balun in a simple dipole. Something on the order of a 20M? Thanks!
How critical is the 'spacing' of the loops around that ring...is it ok to just 'eyeball' it and push/pull the loops until they look 'about right', or do they need to be spaced very precisely? Just coming back to HAM radio after being gone a few years...never got beyond Technician Lic. before having to put things in storage for a few years, and now having to relearn everything.
Thank you for these videos...you explain things in a way that someone with little to no knowledge about radios and radio theory can understand...and that is necessary as many try to overload with information...to be blunt I just want to get on the air and talk to others...yes I will learn (hopefully) as I progress...but for now I just want to get on the air. Thank you for making these videos in terms a beginner/layman can understand.
And I mean no insult to others posting videos on how to build stuff, who go into great detail about radio theory, electrical/electronics stuff, etc. -- hats off/salute to those with the big brains...maybe I will become that well educated about all this at some point, but I'm not there, or even close at this point...and just get overwhelmed by a lot of the information that seems, at this point, to go way over my head.
Thank you for the time and effort of making these videos. 73 WF7BSR
Symmetry is important. One side is electrically opposite the other and they need to cancel each other out when the signals are common mode. So you want each side to be as identical as possible and neat and even as possible. Eyeballing it is fine, as long as they are mirror images of each other. (as close as you can get it.)
Thank you!
Hey Kevin, wouldn't a mix 31 toroid work better for this application (choke)? Thanks for all the great videos!
It's not that critical in a choke. I saw one aussie video where he used a steel bolt. Not as effective, but worked. But, you can always improve on components.
Have you ever tried using those clip on ferrite beads , I seem to be getting quite a noticeable effect from them
Someone said on the net, don't wind chokes on red toroid.
How does it performs?
The type two material which is the one with the red coating, works well from 20 m up through 6 m. At the higher frequencies. There is a table somewhere that shows the different toroid mixes and what frequency ranges they're good at. For the lower HF frequencies you want to use a type 43.
Mr Kevin. TKS fer your knowledge. So I homebrew one 9:1 with an old toroid of an old TV from other video. Works pretty well, driving 10 watts in Portable. In my shack I use an A99, but sometimes I have a lot of QRM, so where could I put this 1:1, near antenna or near my radio. TKS a lot and 7351. I will do with a toroid from an old TV to.
It will choke off common mode noise if you put it at either end. However, if you put it at the antenna end, then you'll need to add a counterpoise wire to your 9:1 since it won't be able to use the coax shield as one. The choke will isolate the coax from the antenna electrically.
You need the right core, the right turns and the right wire and there is no one right of all of that. That said 2 x 240-43 with 9T rg58 will run very easy >2kw from 160-10m.
thanks
Thx Kevin interesting video
I think you should reprint the box and allow a channel for an o-ring. TSC has a lot of stock sizes.
Or just get some flexible materical filament and print an O ring.
Although it makes no difference as the toroid remains a 1:1, each time the wire passes through the centre counts as a winding and therefore there are 9 in the work shown. I believe you didn't count the 'pass over' when counting the 8, or am I seeing it wrong?
I want to try twisting the 2 wires together using enamel wire. I would sweep it into a dummy load. K5LYT
I've seen some recommend that the common mode choke be placed close to the transmitter, rather than at the antenna. This suggests that the shield on the coax between the common mode choke and the unun at the antenna (for an end fed) is serving as part of the counterpoise. I'm curious what your thoughts are on this.
Yeah, that would work. But then you have the problem of the coax radiating RF inside the shack. If you're running power, that RF can follow the mic cord into the audio front end and fuzz up your audio on TX.
It's probably best to put it at the antenna end and then add a counterpoise wire to the unun.
That toroid specs show 10MHz as highest freq. Is that not the case due to the winding?
Как происходит фильтрация помех? Ведь такая намотка не может быть фильтром! Или вы используете отдельное устройство, например ферритовые кольца на кабель?
You state RF coming back on the coax shield. But you don't translate what that RF means; namely RX noise.
For what frequency range is this 8 winding 1:1 UnUn intended. Looks to be 8 windings to me.
What about the reactance of the Balun in relation to changing the length of the feed line ?
Kevin, you could lose a full db on the tarnished threads of the SO-239s on the choke. A small brass brush should get rid of the tarnish and give you a nice clean connection.
The brush could also remove some of the silver plating. I have some silver polish around here somewhere.
Kevin Loughin if it is silver no need to remove tarnish.
The tarnish is silver oxide, and is conductive, yes. It's not as conductive as clean silver, though.
That is untrue. Silver that is tarnished is as good a conductor of RF as bright and shiny silver. If the shell of a PL-259 is tight, the conductivity is excellent, whether it is silver plated or nickel plated. Typical loss thru a PL-259 is maybe .05 db.
What does the vswr plot from 1.8-54mhz look like
Would have been better explaining more about the electrical/RF properties of the 1:1 choke, how it works and why it is needed than how to make a plastic box, just saying
Would it hurt if the 1:1 was 20ft from the 9:1 as long as it was before it entered the house?
Yes, however, the length of coax between the 1:1 and the antenna will become part of the antenna and may throw things off a bit.
Kevin, I really enjoy your videos. Do you have any SWR and common mode choke measurements for the frequency range you intend to use the balun?
That would vary widely with the wire length, counterpoise length, and feedline. I use it with a non-resonant length of wore and a tuner. The 9:1 brings impedance down to a range that's easier for the tuner to handle.
Have you everything to just add the 1:1 inside of the 9:1 and tide them together.
That certainly is possible. However, with a 1:1 choke electrically isolating the feed line from the antenna, you'll need some length of counterpoise wire off the ground side of the 9:1 or it won't work well.
I am new to this! I don't understand why there are so many ways to do a 1:1. What is the difference in a current Balum and common mode choke? It looks like they are doing about the same thing, to block unwanted current coming down the shield of the coax. And for us broke people can I just use a box from Home Depot?
There are many ways to make a common mode choke. They mostly work the same and solve the same problem.
This is just one way.
If you're going to be permanently mounting the box outside, a weatherproof project box is probably a superior option. Most 3d printer filaments have poor thermal and UV stability, and waterproofing can be a significant challenge. A commercial weatherproof project box takes care of all of those challenges.
For the 1:1 does it make much difference whether you wind 4, 5 or 6 turns on each side?
Probably not, as long as the two sides are symmetrical.
2 questions for you. Did this common mode choke end up in the final installation? and also can I use enamelled copper wire in place? I'm assuming it'll be the same as it's solid wire. Cheers from Australia. VK4MGL
Actually I didn't end up using it on the vertical. I needed to get the counterpoise wires installed and buried. Once I'd done that, I had so little RF on the coax, I didn't bother putting the choke in. But I've used it elsewhere.
Yes, you can use magnet wire. You need to put Teflon tape on the core to insulate it from the wire, especially if the core has sharp edges that could cut through the enamel insulation.
Kevin Loughin ok yes figured that was the case. Thanks.
I found some 12ga enameled wire online. How much power would that handle? I think I will need to go to a bigger thyroid but not much bigger because the enameled 12ga isn't much bigger than the 16ga with that insulation. But before I spend the money to get the things I want to be sure it will handle over 100- 200 watts.
For us broke people maybe you can tell us something that we don't need $500,000 equipment to do this. Waterproof PVC box should work but not sure what size is the trouble. Maybe I make the choke and take it with me when I go to the Box store to make sure that the box is big enough.
The 12 gauge wire and perhaps a 2-inch toride will handle 200w just fine. However, you need some kind of PTFE tube to put over the wire for insulation, the enamel is just too thin, and you could have arcing to the Core.
@@loughkb they use enameled wires in high voltage transformers and they don't arc. Is the wire doing to have that high voltage in this?
@@donaldsmith3048 RF voltage behaves a bit differently due to the high frequency. Also, winding it over the edges of the torroid can rub the enamel thin or through.
@@loughkb I wasn't thinking about the difference in RF voltage. I was just thinking that the larger wire should go much more power, and without that thick plastic around it would fit better. The movement after it is made can be stopped with hot glue or other things. But I need to see what I can find to cover the wires to help with the RF voltage. Thank You.
You could have used 2 different wires of the same type in different colors.
Is it better to export the file as G-Code and load that into the 3D printer.
That's the only way you can do it. You use slicing software to create the Gcode, which all the printer understands.
Hi Kevin,
Nice video on winding the 1:1 choke. Looking to make a legal limit one. Was thinking about stacking two T240 31 mix toroids and using 12 ga wire. When you designed the enclosure, though you would have dropped the corner posts by 2mm (made them 26mm high) so that the lid would have the ridge fit the inside dimensions of the bottom half of the enclosure. 73 WB3BJU
Hi Don. Yeah, I thought about those corners after the fact. It was a design on the fly thing. Easy enough to revise the model and just reprint another one.
What frequency range?
What program is that..and is it in linux..??? thanks..
What is the size of the toroid you used?
I think I mentioned that in the video. Either a T130 or a T200. Can't quite remember off the top of my head.
I've seen others make an RF choke by winding about 10 turns of coax. Is your's better or is it serving a different purpose entirely?
In theory, it's supposed to do the same. I've tried the air-choke with the coax and didn't get the best results. It actually seemed to reduce the antenna's performance in my case.
I just use rolled up coax.
An "ugly balun" as those are often called do work, but not as well. Also, if you roll it to tight, the center conductor can push it's way through the dialectric and contact the braid.
@@loughkb people have hooked things up with no balun and got it to work. I know how to properly handle coax. One of my younger ham friends put up a multi band dipole and told me it will not load up well anywhere. I had him bring me the 16 dollar new price 1:1 balun he bought from HRO. I tested the balun(yes I know how) and told him what a POC. take it back and get your money back. what to do coax already cut to short to coil it. I told him hook the coax to the dipole and try it. he got luck and everything worked great. when I build something like an inverted V. I will use the "Collins" 1:1 coax balun. yes Collins knew how to do that. in ham radio its important to think things over but in a pinch try it and see.
Would this be known as a un-un.
That's kind of a tricky question. Only in the sense that it's connecting and unbalanced feed line to another unbalanced feed line. But the term unun is usually applied to a transformer that matches different impedance, so in that sense, no.
Kevin Loughin
Rather think that it's also a 1:1 un-un. Might also be a 1:1 current balun but I'm guessing a bit there.
In preventing the lower run of coax into the rig, from being part of the antenna, you might have the bonus of lowered local hash noise!
If you goof over the 3D printing, can the wasted material be reused or does it come shaped like ingots or maybe tape/rods?
When casting lead, used material can be thrown back in the melting pot but maybe not so for3D printing?
Are programming softwares interchangeable on various printers?
Is there any provision for duplicating an existing object without the drawing board process?
Hope you can help. Never encountered 3D printing before...fascinating !!
Thanks in advance and also for the series of videos.
73 de G3NBY
.
Hey Kevin... just a note - the word balun is a combination-contraction of balanced-unbalanced and is pronounced in the same manner as each root word. i.e. you would say the first half of the word "bal" in the same way you would pronounce "balanced" and the second half as "un." You had mis-pronounced it by saying "ballin" or "bawlin"... not trying to split hairs, but it is distracting to have a word mis-pronounced! Thank you for all you do! 73/KK0DJ
another radio amateur he tell me this is unsafe to create it with the plastic they using the 3d printers in bad weather and with the sun this box it will be destroy with the time so lost time to create it and print it ?
It depends on how you use it. If it's going to be out in the sun all of the time, you might want to use a different material or a different box. Or just print a new one once a year to replace it with. No big deal.
Unless your hamshack is right in the near field of your transmitting antenna, and you have RF in the shack, there is no reason to put a "common mode" choke in your feedline. Many of these TH-cam videos propagate more lore and myth about antennas, than truth and fact. Buy some antenna books and start learning about antennas, the good, the bad and the ugly.
Depends on the antenna, of course. A feedline feeding a resonant dipole will have less RF on it than the same feedline driving an EFHW. Any time your feedline is acting as a counterpoise, it will have RF on it.