I was researching about coils and have read in patent from Nikola where he used 2 wire conductor like in his bifolar coil to increase capacitance by connecting end of one of two wires to begining of other creating double loop of tranformer and he said that would increase frequrncy response and allow greater current flow in coil as capacitance is evenly distributed along the coil countering inductance. As the difference in such case of potential between each turn is half of what normaly is he found it very useful at higher frequencies and voltages. Also submersion in oil would help with temperature but also with leakage that occurs in air as dialectric. I am just in wonder would any of those affect RF transformer in this aplication. I guess you gave me a idea to test with VNA which I learned how to use thanks to you and few other youtubers. Thank you for your videos I love this kind of experiments.
The very first 9:1 ununs I assembled were not shown in this video. I made a set, one twisted pairs, the other not. The twisted pair hurt the performance. I also tried a coaxial version which I could not get to perform as well. You will find the my posts about those on EEVBLOG.
The box would probably start to melt around 500 Watts. At 1K or 1.5K it would probably be so hot under continuous use it would catch on fire. The core size is woefully undersized for 1.5KW which is legal limit for amateur radio. I have built 9:1 UNUN's that can handle well over 1.5KW they have 3 stacked cores. Heat is your enemy. If it gets to hot you start to loose the magnetic properties of the core and it can get to a thermal runaway condition. Magnets don't like heat. Mike KC3OSD
Thanks Joe. Judging from the seller's claims for that size of Mix 2 core, I suspect this is about to get ugly. Update: From all I've read about RF toroids, the various mixes of powdered iron cores (like this one,) are best for narrow frequency range (tuned) impedance matching transformers, while the ferrites are usually best for broadband impedance matching transformers, (like this application.) Also, the Mix 2 cores, (red and clear coat powdered iron cores like this one,) start getting pretty lossy up around 10 meters so they typically switch to Mix 6, yellow and clear coat.) So all in all, this core is likely to melt right through that plastic box when 1,500 watts gets sent through it for any period of time, assuming the transmitter won't just shut down first from the high VSWR on 160 and 80 meters, and possibly 10 meters too may cause a melt-down from the reduced efficiency and therefore increased core heating on 10 with Mix 2. I've done no testing to verify this, just done a lot of reading online from the pages of knowledgeable people who HAVE done the experimentation. Ferromagnetics is a large, involved field, so I figured that reading was a lot less work for me and saved me from buying a lot of wrong cores. There's just a whole lot to know, and unfortunately, there are quite a few manufacturers who are selling products that use the wrong materials for the job.
All that SWR sweep is under the assumption that the antenna presents a flat 450 ohm impedance across the entire HF range. There's basically one way to do that, and it's a resistor. Transformers like that almost always require a transmatch, tuner, or some other matching network. I'm more of a fan of DG0SA's (sk) designs for transformers and chokes. 73 de w8tam
All that SWR sweep was with basically a resistive load, except where I show the two back to back, then into a resistive load. This was done to compare transformers over a wide band.
Thank you Joe....new subscriber couple weeks ago. I so enjoy your experience, knowledge and discipline analyzing and making measurements that are meaningful and drawing some useful conclusions. I'm anxious to use your software for the NanoVNA. I have the H-4 model. Lab View has a "community" version available -- will that work with your software? I just recently found this on the NI website stated for "non-commercial" use only. I would very much appreciate a bit of guidance in that regard. Many, many thanks!!
Ron, you do not need LabView installed to run the software. It's like any other executable. I have not had any luck with the H4. Because it uses the older protocol (how the PC talks to the device), it would only work with my older software. Others have claimed to use it but I am not sure to what extent. For development work, I will not use the community edition. It requires an internet link, meaning it could go away. It's just too risky to invest any time into. I would have continued moving towards their latest 64-bit tools but that's no longer being considered with the advent of their subscription / extortion business model. I suggest you use one of the open source packages instead. The most popular one was written in Python and will run on Windows, LINUX or Mac. It's also better supported and has a large following.
General Class HAM here (KI5QFC) ... I think you have a bit of a misunderstanding about what the difference between a End-Fed Half-Wave and a End-Fed Random Wire... The End-Fed Half-Wave is a resonant antenna but it needs a 49:1 unun (transformer)to match the ~2,500 Ohms impedance of the antenna to the feed line (50 Ohms) The 9:1 unun is used for a End-Fed Random Wire antenna... You are looking for a low SWR on an antenna that HAS to have a high SWR to work... The End-Fed Random Wire HAS to be used with an antenna tuner... The 9:1 is used to match the impedance of the antenna (~450 Ohms)to the feed line (50 Ohms) or the radio directly (50 ohms). You need to cut the wire so that it is not a halfwave multiple of any frequency you want to use. Any time the antenna becomes resonant at the frequency you are transmitting at, the impedance will start to rise VERY quickly, and you need the 49:1 unun, but no tuner. The advantage of the random wire antenna is that you can pick a length of wire that is NOT resonant at any of the frequencies you are using, and it will work on ALL of them with just a antenna tuner.
Do NOT use star washers with RF and power. I have burned up many of them even with moderate power. Once that happens your connections are lose, plastic melts I even had them get so hot they un-soldered the wire from the lug.
I spent a little time searching for any documents that would backup your claim about the use of star washers and found nothing. That said, I had several people contact me about my use of a torque wrench on SMAs and how it would tear the connectors from the boards. I suspect your comment is similar.
If you read the title, this video was assembling a kit, not a designing a transformer. You would need to contact the designer and ask them about their choices.
You provided no time stamp. I show two different programs I wrote. One for the low cost VNAs, the other specific for this experiment. I made somewhat of a follow up video showing a home made Watt meter. ruclips.net/video/JHsgbu7brYI/видео.html
@@AndrewMurphy8383 It's very rare I would feel any need to name the software I write. In the case of the VNA, I did name it and you can see it on the upper area of the program. For the other, there is no name. If you like, we can call that program George if that will make you happy. Consider that software is no available to the public and I doubt I even have it anymore. It was just a quick toss together to run the experiment. Much like a lot of the programs I write.
@@germanjohn5626 I will need to do some research, because iron powder cannot be used for RF, so there must be some other alloy etc. that is called "iron powder" and can handle higher frequencies without huge loss.
@@joesmith-je3tq Please do not read in that I am having a go at you for doing this video, the build or anything. I am talking about the product, NOT YOU!
@@stevenbliss989 Work up what you feel this kit should cost and itemize it. I would include any details on what you feel is their break even point. Should be interesting.
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Very interesting. Been years since I've look at these kinds of measurements. Thanks for the look and your expertise.
That makes sense more turns to the coil would mean higher ramp up time
I was researching about coils and have read in patent from Nikola where he used 2 wire conductor like in his bifolar coil to increase capacitance by connecting end of one of two wires to begining of other creating double loop of tranformer and he said that would increase frequrncy response and allow greater current flow in coil as capacitance is evenly distributed along the coil countering inductance. As the difference in such case of potential between each turn is half of what normaly is he found it very useful at higher frequencies and voltages. Also submersion in oil would help with temperature but also with leakage that occurs in air as dialectric. I am just in wonder would any of those affect RF transformer in this aplication. I guess you gave me a idea to test with VNA which I learned how to use thanks to you and few other youtubers. Thank you for your videos I love this kind of experiments.
The very first 9:1 ununs I assembled were not shown in this video. I made a set, one twisted pairs, the other not. The twisted pair hurt the performance. I also tried a coaxial version which I could not get to perform as well. You will find the my posts about those on EEVBLOG.
The box would probably start to melt around 500 Watts. At 1K or 1.5K it would probably be so hot under continuous use it would catch on fire. The core size is woefully undersized for 1.5KW which is legal limit for amateur radio. I have built 9:1 UNUN's that can handle well over 1.5KW they have 3 stacked cores. Heat is your enemy. If it gets to hot you start to loose the magnetic properties of the core and it can get to a thermal runaway condition. Magnets don't like heat.
Mike KC3OSD
I'll let you test that.
Thanks Joe. Judging from the seller's claims for that size of Mix 2 core, I suspect this is about to get ugly.
Update: From all I've read about RF toroids, the various mixes of powdered iron cores (like this one,) are best for narrow frequency range (tuned) impedance matching transformers, while the ferrites are usually best for broadband impedance matching transformers, (like this application.) Also, the Mix 2 cores, (red and clear coat powdered iron cores like this one,) start getting pretty lossy up around 10 meters so they typically switch to Mix 6, yellow and clear coat.) So all in all, this core is likely to melt right through that plastic box when 1,500 watts gets sent through it for any period of time, assuming the transmitter won't just shut down first from the high VSWR on 160 and 80 meters, and possibly 10 meters too may cause a melt-down from the reduced efficiency and therefore increased core heating on 10 with Mix 2.
I've done no testing to verify this, just done a lot of reading online from the pages of knowledgeable people who HAVE done the experimentation. Ferromagnetics is a large, involved field, so I figured that reading was a lot less work for me and saved me from buying a lot of wrong cores. There's just a whole lot to know, and unfortunately, there are quite a few manufacturers who are selling products that use the wrong materials for the job.
All that SWR sweep is under the assumption that the antenna presents a flat 450 ohm impedance across the entire HF range. There's basically one way to do that, and it's a resistor. Transformers like that almost always require a transmatch, tuner, or some other matching network. I'm more of a fan of DG0SA's (sk) designs for transformers and chokes. 73 de w8tam
All that SWR sweep was with basically a resistive load, except where I show the two back to back, then into a resistive load. This was done to compare transformers over a wide band.
Thank you Joe....new subscriber couple weeks ago. I so enjoy your experience, knowledge and discipline analyzing and making measurements that are meaningful and drawing some useful conclusions. I'm anxious to use your software for the NanoVNA. I have the H-4 model. Lab View has a "community" version available -- will that work with your software? I just recently found this on the NI website stated for "non-commercial" use only. I would very much appreciate a bit of guidance in that regard.
Many, many thanks!!
Ron, you do not need LabView installed to run the software. It's like any other executable. I have not had any luck with the H4. Because it uses the older protocol (how the PC talks to the device), it would only work with my older software. Others have claimed to use it but I am not sure to what extent.
For development work, I will not use the community edition. It requires an internet link, meaning it could go away. It's just too risky to invest any time into. I would have continued moving towards their latest 64-bit tools but that's no longer being considered with the advent of their subscription / extortion business model.
I suggest you use one of the open source packages instead. The most popular one was written in Python and will run on Windows, LINUX or Mac. It's also better supported and has a large following.
General Class HAM here (KI5QFC) ... I think you have a bit of a misunderstanding about what the difference between a End-Fed Half-Wave and a End-Fed Random Wire... The End-Fed Half-Wave is a resonant antenna but it needs a 49:1 unun (transformer)to match the ~2,500 Ohms impedance of the antenna to the feed line (50 Ohms)
The 9:1 unun is used for a End-Fed Random Wire antenna... You are looking for a low SWR on an antenna that HAS to have a high SWR to work... The End-Fed Random Wire HAS to be used with an antenna tuner... The 9:1 is used to match the impedance of the antenna (~450 Ohms)to the feed line (50 Ohms) or the radio directly (50 ohms). You need to cut the wire so that it is not a halfwave multiple of any frequency you want to use. Any time the antenna becomes resonant at the frequency you are transmitting at, the impedance will start to rise VERY quickly, and you need the 49:1 unun, but no tuner. The advantage of the random wire antenna is that you can pick a length of wire that is NOT resonant at any of the frequencies you are using, and it will work on ALL of them with just a antenna tuner.
No antennas were harmed during this test.
Do NOT use star washers with RF and power. I have burned up many of them even with moderate power. Once that happens your connections are lose, plastic melts I even had them get so hot they un-soldered the wire from the lug.
Please supply a reference for this claim. Or is this comment just based upon your personal experience?
I spent a little time searching for any documents that would backup your claim about the use of star washers and found nothing. That said, I had several people contact me about my use of a torque wrench on SMAs and how it would tear the connectors from the boards. I suspect your comment is similar.
Why not use a 240/43 core?
If you read the title, this video was assembling a kit, not a designing a transformer. You would need to contact the designer and ask them about their choices.
what software was you using
You provided no time stamp. I show two different programs I wrote. One for the low cost VNAs, the other specific for this experiment. I made somewhat of a follow up video showing a home made Watt meter. ruclips.net/video/JHsgbu7brYI/видео.html
@@joesmith-je3tq it was the only one that you used first one
@@AndrewMurphy8383 14:48, 21:31 & 41:35, two different programs. Looks like you are asking about the software for the VNA.
@@joesmith-je3tq ok i look at it when i can get get a break and let you know i dont know why you just cant tell me the name of the the two software
@@AndrewMurphy8383 It's very rare I would feel any need to name the software I write. In the case of the VNA, I did name it and you can see it on the upper area of the program. For the other, there is no name. If you like, we can call that program George if that will make you happy. Consider that software is no available to the public and I doubt I even have it anymore. It was just a quick toss together to run the experiment. Much like a lot of the programs I write.
Looking at the temps you show, at 1.5kW it will MELT!!!!!!!!!!!!!!!!!!!!!!!!!
...now at the end of your video, the $45 seems like crap, but 1.5kW ...I seriously doubt it, especially sinc oe you said it is iron powder mix!
Actually, I just read what the supplier had posted in their ad.
Powdered iron core for RF???? Did not know you could do that without MAJOR core loss???
Powdered iron cores are commonly used for RF
@@germanjohn5626 I will need to do some research, because iron powder cannot be used for RF, so there must be some other alloy etc. that is called "iron powder" and can handle higher frequencies without huge loss.
I could buy the parts for a TINY FRACTION of the $45 being asked, ....WTF?????????????
In business, we would call that profit.
@@joesmith-je3tq There is profit and there is profit. It should be a win-win. This is NOT!
@@stevenbliss989 It's not my business and I have would have no way to know what their costs and margins are.
@@joesmith-je3tq Please do not read in that I am having a go at you for doing this video, the build or anything. I am talking about the product, NOT YOU!
@@stevenbliss989 Work up what you feel this kit should cost and itemize it. I would include any details on what you feel is their break even point. Should be interesting.
Awesome ! Exactly what i needed ! ea7knw